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Sega/Stern White Star Repair

2023-03-23T09:41:05Z

Jimpal: Reverted edits by Jimpal (talk) to last revision by ForceFlow

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

==Introduction==

 

==Games==
===Sega===
*Apollo 13
*Goldeneye
*Twister
*Independence Day
*[[Space Jam]]
*Star Wars Trilogy
*The Lost World Jurassic Park
*The X Files
*[[Starship Troopers]]
*Viper Night Driving
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park

===Stern===
*Striker Xtreme
*[[Sharkey's Shootout]]
*High Roller Casino
*Austin Powers
*[[Monopoly]]
*NFL
*Playboy
*Roller Coaster Tycoon
*[[The Simpsons Pinball Party]]
*Terminator 3: Rise Of The Machines
*The Lord Of The Rings
*Ripley's Believe It Or Not
*Elvis
*Grand Prix
*The Sopranos
*NASCAR

==Recommended Documentation==
===Manuals===
The owner's game manual is a handy resource to have for general game operation, game settings & diagnostics, switch & lamp matrices, fuse lists, circuit boards and parts, playfield assemblies, some basic schematics, and wiring diagrams. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended [http://pinwiki.com/wiki/index.php?title=Pinball_Parts_Suppliers pinball parts suppliers]. Some Stern White Star Game manuals are available in PDF form on the Stern Pinball website. They are on the game specific pages of the Stern website. An index of games can be found in the right margin [https://sternpinball.com/support/game-manuals/ here]. 

As of April 2014, the Stern Pinball website no longer archives theory of operation and board schematics in PDF format. 

Be aware that although rare, some factory documentation contains errors in schematics, wiring, switch/lamp matrices, and solenoid assignments.

===Schematics===
Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids.

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===Service Bulletins===
Service bulletins detailed any problems or issues with games that were discovered after they were released.

Service bulletins for all Stern games can be found [https://sternpinball.com/support/service-bulletins/ here.]

As of 2014, service bulletins for Data East and Sega games are no longer directly available on the Stern Pinball website, but [https://web.archive.org/web/20130520091730/http://sternpinball.com/ServiceBulletins.shtml can be found on an older archived version of the website].

{| class="wikitable sortable"
|-
!Service Bulletin
!Date
!Game(s)
!Summary
!Notes

|-
|[[media:Sb166.pdf|166]]
|2006-09-20
|Grand Prix & NASCAR
|Trough Up-Kicker Failure
|
|-
|[[media:Sb162.pdf|162]]
|2006-07-11
|The Simpsons Kooky Carnival, Monopoly, and Titanic Redemption Games
|Electronic Coin Mech Coin Return Lever Sticks
|
|-
|[[media:Sb161.pdf|161]]
|2005-03-21
|NASCAR / Grand Prix
|NASCAR / Grand Prix Enter/Exit Scoop Modification & 1-Way Gate Bracket Update Kit (502-5048-86); ONLY FOR NASCAR/GRAND PRIX GAMES with SERIAL NUMBERS LOWER THAN <195160 (NASCAR) and LOWER THAN < 19620 (GRAND PRIX) Production Prior December 2006
|
|-
|[[media:Sb160.pdf|160]]
|2005-11-08
|NASCAR
|NASCAR SOFTWARE UPDATE (CPU/GAME ROM U210); ONLY FOR NASCAR GAMES with CPU Version 3.30 or LOWER
|
|-
|[[media:Sb159.pdf|159]]
|2005-08-31
|NASCAR
|NASCAR T-Nut Cover & Target Foam Kit (SPI PN: 502-5042-00); EARLY PRODUCTION GAMES ONLY
|
|-
|[[media:Sb158.pdf|158]]
|2005-08-26
|NASCAR
|NASCAR 2-Pin OPTO Ground Connector in Backbox; EARLY PRODUCTION GAMES ONLY
|
|-
|[[media:Sb157.pdf|157]]
|2005-06-20
|Terminator 3, The Lord of the Rings, Ripley's Believe It or Not!, ELVIS, Harley-Davidson 3rd Edition and The Sopranos
|New Version 8 of the Sound Operating System (O/S)* for the White Star CPU/Sound II Board bootFLASH file for EPROM; This new version O/S 8 is compatible with all previous versions of CPU/Snd II ROM’s.

|
|-
|[[media:Sb156.pdf|156]]
|2005-05-05
|The Sopranos
|Cabinet Flipper Switches - Contact Pitting
|
|-
|[[media:Sb155.pdf|155]]
|2005-04-15
|The Sopranos and future Pinball Games
|FYI: Lockdown Assembly & Front Molding Change during the production of The Sopranos Pinball and future Pinball Game Titles
|
|-
|[[media:Sb154.pdf|154]]
|2005-02-20
|Lord of the Rings
|Lord of the Rings Post Upgrade Kit (502-5034-00) ONLY games prior to Feb. 2005 (production of LOTR games after Feb. 2005 have post in place).
|
|-
|[[media:Sb153.pdf|Nr. 153]]
|2004-12-15
|Ripley's Believe It or Not!
|Ripley's Believe It or Not! Software Update
|
|-
|[[media:Sb152.pdf|Nr. 152]]
|2004-08-27
|general
|FYI: STERN Pinball Flipper Evolution
|
|-
|[[media:Sb151.pdf|Nr. 151]]
|2004-07-20
|Lord of the Rings
|Potential flipper & ring magnet fuse fatigue
|
|-
|[[media:Sb150.pdf|Nr. 150]]
|2004-06-21
|general
|Back to Basics: Insertion/Replacement of EPROMS in SPI Games
|
|-
|[[media:Sb149.pdf|Nr. 149]]
|2004-05-18
|Ripley's Believe It or Not!
|Potential Ball Trap by the Upper Left Pop Bumper (ask your Distributor for SPI Kit Nr. 502-5025-81)
|
|-
|[[media:Sb148.pdf|Nr. 148]]
|2004-04-29
|The Lord of the Rings
|Balrog LED Module Installation, SPI Kit Nr.:502-5022-00
|
|-
|[[media:Sb147.pdf|Nr. 147]]
|2004-01-19
|The Lord of the Rings
|Diverter Gate Adjustment Procedure
|
|-
|[[media:Sb146.pdf|Nr. 146]]
|2003-12-18
|The Lord of the Rings
|FYI: The Lord of the Rings Tower Eject Learning Mode
|
|-
|[[media:Sb145.pdf|Nr. 145]]
|2003-12-09
|Terminator 3 Rise of the Machines
|T3 Auto Launch Diode Harness Installation (SPI Part Number 502-5017-00)
|
|-
|[[media:Sb144.pdf|Nr. 144]]
|2003-12-09
|The Lord of the Rings
|The Lord of the Rings Spanish Display & Speech Available
|
|-
|[[media:Sb143.pdf|Nr. 143]]
|2003-10-22
|Terminator 3 Rise of the Machines
|T3 Software Update/Match Feature
|
|-
|[[media:Sb142.pdf|Nr. 142]]
|2003-08-22
|Terminator 3 Rise of the Machines
|T3 Auto Launch Wire(s) or Coil Lug(s) Break Off
|
|-
|[[media:Sb141.pdf|Nr. 141]]
|2003-08-13
|Terminator 3 Rise of the Machines
|Shooter Lane Switch Actuator Adjustment
|
|-
|[[media:Sb140.pdf|Nr. 140]]
|2003-07-24
|Terminator 3 Rise of the Machines
|T3 Software Update v2.04 or Higher Eliminates POTENTIAL Reset Problem
|
|-
|[[media:Sb139.pdf|Nr. 139]]
|2003-05-16
|Monopoly
|F21 (50vdc) Fuse Blows Intermittently, System Checks OK on
|
|-
|[[media:Sb138.pdf|Nr. 138]]
|2003-03-21
|The Simpsons Pinball Party
|The display flashes a Tech-Alert upon Power-Up
|
|-
|[[media:Sb137.pdf|Nr. 137]]
|2002-07-22
|Austin Powers
|CPU GAME ROM v3.01 Bug
|
|-
|[[media:Sb136A.pdf|Nr. 136a]]
|2002-06-21
|Playboy
|U7 Sound ROM Update DOES NOT RESOLVE the problem
|
|-
|[[media:Sb136.pdf|Nr. 136]]
|2002-05-02
|Playboy
|U7 Sound ROM Change
|
|-
|[[media:Sb135.pdf|Nr. 135]]
|2002-05-01
|Monopoly
|Optional Monopoly Butyrate Fix Kit (SPI: 502-5012-00)
|
|-
|[[media:Sb134.pdf|Nr. 134]]
|2002-04-11
|general
|Difficulty in Playfield Glass Removal
|
|-
|[[media:Sb133.pdf|Nr. 133]]
|2002-04-01
|Monopoly / Austin Powers
|CPU/Soundboard Modification Low Volume Setting Hum
|
|-
|[[media:Sb132.pdf|Nr. 132]]
|2002-03-04
|Playboy
|Back To Basics: Using Your Adjustable Outlane Posts
|
|-
|[[media:Sb131.pdf|Nr. 131]]
|2002-01-23
|Monopoly
|Electric Company Sign / Backbox J2 Harness Re-dress
|
|-
|[[media:Sb130.pdf|Nr. 130]]
|2001-12-10
|Monopoly
|Tips & Tricks - The Water Works Rotating Flipper
|
|-
|[[media:Sb129.pdf|Nr. 129]]
|2001-10-22
|Monopoly
|Playfield Mylar, SPI Part Number: 820-5094-00
|
|-
|[[media:Sb128.pdf|Nr. 128]]
|2001-09-19
|Austin Powers
|Code Update v3.00 CPU/Display: Addition of Adj.60: Washington D.C. Enabled (Factory Defaults is "Off")
|
|-
|[[media:Sb127.pdf|Nr. 127]]
|2001-09-19
|Striker Xtreme / NFL
|Plastic Stadium Flashlamp Removal
|
|-
|[[media:Sb126.pdf|Nr. 126]]
|2001-09-19
|general
|The Bubble Level is Back!
|
|-
|[[media:Sb125.pdf|Nr. 125]]
|2001-04-19
|general
|Quick Tip for Display Troubleshooting: U201 White Starboard System
|
|-
|[[media:Sb124.pdf|Nr. 124]]
|2001-03-16
|Sharkey's Shootout/ High Roller Casino
|Software Update: Replay Bug Fix
|
|-
|[[media:Sb123.pdf|Nr. 123]]
|2001-03-06
|High Roller Casino
|Ball Trap Fix @ Bottom Bumper
|
|-
|[[media:Sb122.pdf|Nr. 122]]
|2001-02-22
|High Roller Casino
|Roulette Wheel (Top and Bottom) Assembly
|
|-
|[[media:Sb121.pdf|Nr. 121]]
|2001-02-05
|Harley-Davidson
|Plastic (Butyrate) -15 Support Plate Kit(SPI Nr. 502-5003-67)
|
|-
|[[media:Sb120.pdf|Nr. 120]]
|2000-12-29
|Sharkey's Shootout
|Mystery Ball Magnet Fuse Fatique: CPU Software Code 2.04 Update
|
|-
|[[media:Sb119.pdf|Nr. 119]]
|2000-11-08
|general
|Pinball Preventative Maintenance Inspection
|
|-
|[[media:Sb118.pdf|Nr. 118]]
|2000-08-21
|Striker Xtreme / Sharkey's Shootout
|Drop Target Replacement Procedure
|
|-
|[[media:Sb117.pdf|Nr. 117]]
|2000-06-13
|general
|Please Join our Service Bulletin eMail Distribution
|
|-
|[[media:Sb116.pdf|Nr. 116]]
|2000-06-12
|Titanic
|Titanic Redemption Game Potential Revenue Loss
|
|-
|[[media:Sb115.pdf|Nr. 115]]
|2000-05-03
|Stiker Xtreme
|Stiker Xtreme Earnings
|
|-
|[[media:Sb114.pdf|Nr. 114]]
|2000-02-11
|Harley-Davidson
|Operator Alert #19 - Motor Relay
|
|-
|[[media:Sb113.pdf|Nr. 113]]
|1999-12-10
|Harley-Davidson
|HD Ball Guide... & Butyrate - 16... Kit
|Replace 2 playfield ball guides for games where the serial number falls within 148598-149648. Add protective playfield plastic shield/plate on games where the serial number falls within 148598-150600.
|-
|[[media:Sb112.pdf|Nr. 112]]
|1999-06-07
|A13 >> Current
|CPU U218 & I/O U210 Pin-3 Removal
|
|-
|[[media:Sb111.pdf|Nr. 111]]
|1999-02-18
|South Park
|8MG E-PROM's for Expanded Speech & Sound Capabilities
|
|-
|[[media:Sb110.pdf|Nr. 110]]
|1998-11-24
|Space Jam >> Current
|Modular Stand-Up Targets: a new way to order
|
|-
|[[media:Sb109.pdf|Nr. 109]]
|1998-09-30
|Godzilla
|...Manual Addendum: Flipper Coils
|
|-
|[[media:Sb108.pdf|Nr. 108]]
|1998-08-18
|Prior<<Batman Forever>> current
|"Sega"...& "Data East" ... Flipper Rebuild Kits
|
|-
|[[media:Sb107.pdf|Nr. 107]]
|1998-08-13
|All Games (General)
|Fax Response Survey: How would you like your...
|
|-
|[[media:Sb106.pdf|Nr. 106]]
|1998-06-02
|Multiple Games
|Large Dot Display Optional Enhancement Cable
|
|-
|[[media:Sb105.pdf|Nr. 105]]
|1997-11-21
|The X-Files
|...-Playfield Update Kit (500-6281-00)
|
|-
|[[media:Sb104.pdf|Nr. 104]]
|1997-09-25
|Multiple Games
|Future Parts & Service Pinball ...(Questionaire)
|
|-
|[[media:Sb103.pdf|Nr. 103]]
|1997-07-14
|Playboy thru Rocky & Bullwinkle & Friends
|Solid State Flipper Bd. ( Non E.O.S.) conversion
|
|-
|[[media:Sb102.pdf|Nr. 102]]
|1997-06-20
|The Starwars Trilogy-Special Edition
|FYI: What's New ("Y" Actuator Heavy Duty Sw.)
|
|-
|[[media:Sb101.pdf|Nr. 101]]
|1997-06-10
|The Lost World: Jurassic Park
|Important Unpacking Information
|
|-
|[[media:Sb100.pdf|Nr. 100]]
|1997-05-19
|The Starwars Trilogy-Special Edition
|Software CPU/Display Final Code Version
|
|-
|[[media:Sb99.pdf|Nr. 99]]
|1997-05-13
|Multiple Games
|FYI: Correct P/F Glass Dimensions ...Wide Body
|
|-
|[[media:Sb98.pdf|Nr. 98]]
|1997-04-08
|The Starwars Trilogy-Special Edition
|Addition of Reset Align. Bracket Kit
|
|-
|[[media:Sb97.pdf|Nr. 97]]
|1997-04-08
|The Starwars Trilogy-Special Edition
|X-Wing Motor Bushing
|
|-
|[[media:Sb96a.pdf|Nr. 96A]]
|1997-05-12
|Space Jam >> Current
|Dot Matrix Display Bd. 4X Spacer/2X Bracket
|
|-
|[[media:Sb95a.pdf|Nr. 95A ]]
|1997-04-11
|The Starwars Trilogy-Special Edition
|...Reed Sw. Replacement Kit...&Procedure
|
|-
|[[media:Sb94.pdf|Nr. 94]]
|1997-03-03
|Lethal Weapon 3 >>Current
|Flipper Alignment Spots
|
|-
|[[media:Sb93.pdf|Nr. 93]]
|1997-01-27
|Space Jam
|FYI: ...problem in... I/O Power Driver Boards
|
|-
|[[media:Sb92.pdf|Nr. 92]]
|1996-12-05
|Apollo 13 >> Current
|FYI: MOSFETs in the White Star Bd. System
|
|-
|[[media:Sb91.pdf|Nr. 91]]
|1996-11-27
|Twister
|Magnet Processor Bd. & Disc Motor Updates
|
|-
|[[media:Sb90.pdf|Nr. 90]]
|1996-11-20
|Space Jam >> Current
|FYI: Sega Showcase Backbox
|
|-
|[[media:Sb89.pdf|Nr. 89]]
|1996-11-19
|Apollo 13 >> Current
|FYI: Switches
|
|-
|[[media:Sb88.pdf|Nr. 88]]
|1996-10-14
|All Games (General)
|Excerpt From Customer Fax
|
|-
|[[media:Sb86.pdf|Nr. 86]]
|1996-09-03
|Independence Day
|Potential Ball Trap in the Plastic Under-Trough
|
|-
|[[media:Sb85.pdf|Nr. 85]]
|1996-05-15
|Twister >> Current
|New 2-Flipper Theory of Operation and Schematic
|
|-
|[[media:Sb84.pdf|Nr. 84]]
|1996-03-05
|Golden Eye
|Fuse/Power Updates
|
|-
|[[media:Sb82.pdf|Nr. 82]]
|1996-01-23
|Apollo 13 >> Current
|The New "White P Star Board System"
|
|-
|[[media:Sb81.pdf|Nr. 81]]
|1996-01-09
|Apollo 13
|System Update
|
|-
|[[media:Sb80.pdf|Nr. 80]]
|1995-12-21
|Apollo 13
|Theory of Operation: P/F Mag. Intrface & 7-Seg.
|
|-
|[[media:Sb79.pdf|Nr. 79]]
|1995-12-18
|Apollo 13
|5 Amp to 3 Amp Slo-Blo Fuse Change
|
|-
|[[media:Sb77.pdf|Nr. 77]]
|1995-08-24
|Current Games
|"What is this pinball machine trying to tell me?"
|
|-
|[[media:Sb75.pdf|Nr. 75]]
|1995-08-22
|All Games
|CPU Board - Blanking Circuit Theory of Operation
|
|-
|[[media:Sb72.pdf|Nr. 72]]
|1995-02-17
|Mary Shelley's Frankenstein
|Creature: A Technical Overview
|
|-
|[[media:Sb70.pdf|Nr. 70]]
|1995-02-14
|Mary Shelley's Frankenstein
|Software Change Notice
|
|-
|[[media:Sb68.pdf|Nr. 68]]
|1995-01-27
|Frankenstein (+ games hereafter)
|New Service Feature: Bi-Directional Aud/Adj/Diag.
|

|}

==Technical Info==
===The White Star Board Set===
[[File:Stern WS Boardset.JPG|left|thumb|300px|Typical Early Stern White Star Boardset (Monopoly)]] 
The White Star System board set consists of three boards mounted to the the back box, but four boards total. The CPU / Sound board, I/O Power Driver board and the Display Power supply. Additionally, there is a dot matrix display controller mounted to the backside of the dot matrix display. On some games, the dot matrix display controller is mounted to the backbox instead. 

The first two White Star games, Apollo 13 and Goldeneye, both used an additional solid state flipper control board. Starting with Twister, the solid state flipper board was abandoned, and flipper control became an additional duty for the I/O power driver board. 

In addition to pinball machines, the White Star board set was used in several redemption games made by Sega and Stern. Some of the games are Wack-A-Doodle-Doo, Sega Sports, Titanic, and Monopoly redemption.
 
====CPU / Sound Board====
<center>
<gallery widths=500px heights=300px perrow=2 caption="Generations of the Sega/Stern White Star MPU">
File:A13MPU.jpg|<center>Sega White Star CPU/Sound Board 520-5136-00 Rev. D with 3 channel audio output (Apollo 13)</center>
File:Sega WS CPU Sound 520-5136-16 Rev. D.JPG|<center>Sega White Star CPU/Sound Board 520-5136-16 Rev. D (Wack-A-Doodle-Doo)</center>
File:Stern WS CPU sound.JPG|<center>Stern White Star CPU/Sound Board 520-5136-16 Rev. E (Monopoly)</center>
File:SternWhiteStarAtmelProcessor.jpg|<center>Stern White Star CPU/Sound Board II 520-5300-00 (LOTR and forward). U201, U213, and U413 are socketed on this board as a result of alkaline damage abatement.</center>
</gallery>
</center>
 

There are two versions of the White Star CPU/Sound board.

The board used in Sega machines starting with Apollo 13 (A13) and Stern machines up to Terminator 3 (T3) are the standard version as shown above with the BSMT2000. There were different revisions of this board, which included slight component changes and modifications. However, there were some distinct changes to the board from revision D to revision E. The Q9 transistor located just below U212 (RAM memory) was removed, and a two pin jumper (JP1) was added. Additional circuitry allowed for increased RAM memory from 8K to 32K. Jumper JP1 is used to select between use of a 6264 or a 62256 RAM. '''Note:''' While a 62256 RAM can be used in any game MPU, Sharkey's Shootout specifically requires a 62256 RAM. 

Stern machines starting from Lord of the Rings (LOTR) used a different version of the White Star CPU/Sound board called White Star CPU/Sound Board II or more commonly WhiteStar (modified), part #520-5300-00. Stern had this in-between version made because the BSMT2000 audio chip wasn't available anymore and having it reproduced was too expensive. The White Star II therefore uses an BSMT2000 emulation circuit consisting of an Atmel AT91R40008 microcontroller and an Atmel AT49BV1614-11TC 16Mbit flash memory. Later boards use a AT49BV162AT-70TI flash memory chip. Both flash chips are obsolete now. The boards are known for sudden sound failures sometimes because of a bad flash chip and it is advisable to buy a spare. If the amplifier section is good the most common cause for sound failures is the U414 Xilinx CPLD. This chip is a programmed by Stern via the JTAG connector. While some repairmen have the skill to replace the chip, only Stern can "flash" the code into the chip.

Note: Stern states that the Atmel version board is backwards compatible with the standard (BSMT2000) version, so it can be used in *some* White Star based games (in most cases, Stern branded White Star games only - including South Park and Harley Davidson) prior to LOTR as well. However, the only games which the board can be installed in must use 8mb EPROMs for the sound section versus the 4mb EPROMs more commonly found on Sega White Star based games. If the CPU/Sound board II is used in early games, Starship Troopers for instance, some sounds may not render correctly. 

Additionally...The original BMST2000 based board is not forward compatible with later games like LOTR, etc. 

The BSMT2000 based White Star sound system is nearly identical to the sound circuitry found on Data East/Sega soundboards 5020-5050-0x, 5020-5077-00 and 5020-5126-02.

The board uses TIBPAL16L8 PAL ICs. These are programmable logic chips Stern used to condense a great deal of TTL logic into a single chip. Each PAL is marked with a colored dot for identification and configuration management. U213 is one of these PALs that is within the battery corrosion area. It is readily available, already programmed under part number 965-6504-00 (blue dot), the only exceptions to the blue dot being Sharkey's Shootout which uses part number 965-5023-00 (gold dot) and Lord of the Rings LE with a shaker motor installed which uses a different part number (the standard LOTR without a shaker motor uses the standard 965-6504-00 but the software version supporting the shaker motor will only run on the alternative U213).

There are two more PAL chips on the board at U19 (yellow dot, 965-0136-00) and U20 (white dot, 965-0137-00). These aren't needed very often for repair of the sound section but they do fail now and then.
 
Sega first used standard TIBPAL chips and later switched to reprogrammable PALCE devices. The latest boards from Stern use GAL chips. In the old PAL chips, fuses are burned so they do not have a data retention period. For the programmable logic chips the data retention period is generally specified at 20 years or more at operating temperature. The first White Star boards are from 1995 Beginning in 2015, all with reprogrammable chips begin to exceed the data retention period and although big problems are not to be expected, it wouldn't be surprising if these parts begin to fail.

The programmable logic in the board design makes it harder to repair the boards because of the grey area it causes in the schematics as there aren't any logic diagrams of these available. In short; you don't know what they do so you don't know what the output should be.

'''"Blink Codes"''' do not exist for the 68B09E or the Atmel based MPU. With one exception (Atmel based board) anything blinking is a side-effect of improper board operation. The blinking may help you diagnose the actual board problem, but blinking LEDs are not driven with intent by the processors. i.e. There are no "Bally -17-like Blink Codes".

The single exception to this is LED1 on the Atmel based MPU. LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin # 157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another).

There are two [http://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] (Joint Test Action Group) connectors available on the Atmel based board. One connects to the Xilinx [http://en.wikipedia.org/wiki/Complex_programmable_logic_device CPLD] (Complex Programmable Logic Device). The other connects to the Atmel R40008 processor. The JTAG interfaces to this board and their use have not been documented publicly.

As of April 2014, schematics for the 520-5136-16 board are no longer available from Stern's website. 
As of April 2014, schematics for the 520-5300-00 board are no longer available from Stern's website. 

=====BSMT2000 DSP Info=====
[[File:BSMT2000.jpg||left||thumb||300px||BSMT2000 audio chip]] 
Like the earlier Data East boards, the first White Star generation uses a TI DSP for sound processing. The chip is just a relabeled mask programmed stock Texas Instruments TMS320C15NL-25 DSP. The 8K mask programmed ROM is custom programmed during manufacturing and can not be read out, reprogrammed, or altered in any way. Only the ones labeled BSMT2000 will work in a pinball. For prototyping, the TMS320P15NL-25 and TMS320E15NL-25 were available which included a more-or-less standard 27C64 EPROM. The pictures on the left shows a BSMT2000 and a TMS320P15NL-25 out of a Sega board. The hand labeled chips are rare but if you have one in your pin, you can read it out. The security fuse was not set on the device in the picture. If you build an adapter using a 27C64 and some logic which puts the DSP in microprocessor mode and does the address decoding it might even be possible to use the C10 and C15 devices because the internal ROM is not used in this mode.
 

=====WhiteStar Switch Circuitry=====
Both versions of rhe WhiteStar CPU/Sound board employ an 8 by 8 (8 switch columns, 8 switch rows) switch matrix. In addition to the typical switch matrix, an extra column of switches, which are dedicated to specific functions like coin door switches, appear on all WhiteStar games.

Flipper cabinet and end of stroke (EOS) switches are part of the dedicated switch set on games after Goldeneye.

A combination of microswitches, opto switches, leaf switches (on most drop target assemblies), and reed switches are used.
 

====Power Driver Board====
The Power Driver board supplies fused power, GI power and fusing, lamp matrix circuitry as well as coil and flash lamp drivers. A watchdog circuit also must communicate with the MPU periodically to allow the MPU to boot and operate properly. 

As of April 2014, schematics for the 520-5137-01 board are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-64 board (Sharkey's Shootout Tournament Edition only) are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-01 board (100 ohm resistors added on J2 aux. port lines) are no longer available from Stern's website. 

High current coils (50vdc) 1-8 (group 1) and 9-16 (group 2). Q15 and Q16 typically drive the left and right flippers respectively. 
Low current coils (20vdc) 17-24 (group 1) and 25-32 (group 2). 
 

Please be advised that four revisions of these board exist. The letter after the number indicates the revision. See below. All existing Stern schematics are wrong.

=====Revision D: First revision=====

=====Revision E: Second revision=====
[[File:Stern WS Driver.JPG|left|thumb|300px|Stern White Star I/O Power Driver Board Rev E]] 

*Not fully stuffed. Parts for flipper boards connector J4 and J5 are not stuffed.
 

=====Revision F: Third revision=====
[[File:IO driver rev F.jpg|left|thumb|300px|Rev F of the Sega/Stern IO Power Driver Board.]] 

*C25 changed from 470µF 100V to a 330µF 160V Snap-In capacitor
*U210 pin 3 is cut to allow for a 10% input voltage tolerance before resetting, aka "low line voltage". This was documented in Stern service bulletin #112 which can be found [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf here]. However, a better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 5% (to about 4.75VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

*J2 modified and 100 Ohm resistors R258 to R260, R273 -R277 added (see schematics)

 

=====Revision G: Fourth revision (not documented by Stern)=====
[[File:IO driver rev G.jpg|right|thumb|300px|Rev G of the Sega/Stern IO Power Driver Board.]] 
The most obvious change to the Rev G driver board is the addition of eight 100 ohm resistors under the J2 aux out connector (R258-260, R273-277). This board is backwards compatible with all machines that use the I/O Power Driver board. It is possible to add these resistors to the back of J2 for I/O board Rev F, jumping from the connector pins to the capacitors below the J2 connector to make the board compatible with those games that use the J2 connector.

This is the only version that will work with the TOPS system.

Parts deleted:

*Original R256, D228, R255 and C236 above U210 were removed

Modification 1:

J3 Pin 8 is no longer a key pin. The installed pin is connected to R255/R256 and to C236. The other side of these parts is connected to:

*R255 to D217 banded side like R245 to R251
*C236 to GND like C229 to C235
*R256 to U203 Pin 11 (LST lamp status)

The LST trace to D221 to D227 is missing. The diodes are still connected to the status output line of the VN02 solid state relays. It seems that this status is not queried by the game software or can just be ignored.

Modification 2:

*U210 Pin 3 is connected to R257.
*R257 is connected to GND but not stuffed!

Modification 2 is not necessary. A better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 10% (to about 4.50VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

New parts:
*R255 1K
*R256 39K
*R257 not stuffed
*C235 470pfd

===== Sharkey's Shootout Specific Driver Board =====
[[File:SharkeysShootoutWhiteStarMod.jpg|left|thumb|300px|Cuts and jumpers applied to the Sharkey's Shootout specific I/O Driver Board.]] 
The now defunct Stern web site containing schematics listed a few differences in the I/O Driver Board for Sharkey's Shootout. Those differences are identified in the image at left.

One other change to the board is shown on page 5 of the Sharkey's Shootout unique I/O Driver Board. Fuse F20 is changed from a 3ASB to a 4ASB.
 

===== RottenDog WhiteStar 5V Voltage Regulator =====
[[File:RottenDogWhiteStarVoltageRegulator.jpg|left|thumb|300px|RottenDog LM317 Replacement.]] 
The RottenDog aftermarket power/driver board uses the voltage regulator shown at left, primarily because the older LM317 voltage regulator has gone obsolete.
 

===== Lamp Matrix =====
The WhiteStar system is somewhat similar to previous lamp matrices designed by Data East, Sega and Williams. The main difference is instead of 8 lamp columns and 8 lamp rows (the typical 8 by 8 matrix), two additional lamp rows are used enlarging the matrix to 8 by 10.

===== TOPS Tournament System Driver Board Compatibility =====

Only the latest revision G is compatible with the Stern tournament system (TOPS). With earlier revisions while everything including the tournament sign seem to work ok a tournament can not be started. Pressing the tournament button will result in a 'Tournament Game Paused' message displayed on the DMD. The tournament button itself will also not light up during normal operation. The J3 Aux In connector has an additional pin instead of the key pin on these boards. Because of this the LST line to the lamp drivers goes nowhere on this revision.
 

====Display Controller Board====
[[File:Sega 520-5055-01 DMD Control Board.JPG|thumb|left|300px|Sega White Star Display Controller Board]]
[[File:AnnotatedDMDController.png|thumb|right|300px|Sega White Star Display Controller Board Layout with Ground Connections Shown]] 
The Schematics for this board can be found [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf here]. 

The display controller board doesn't contain circuitry to provide the on board 68B09E with a "reset" pulse. The reset signal is provided from the games MPU via a pin at the ribbon cable connection (J1 pin 20). The surface mount version of the board has provisions to provide a reset signal at U10, but the necessary components are not stuffed.
 

[[File:Stern WS DMD Controller.JPG|thumb|left|300px|Stern White Star Display Controller Board, surface mount version.]] 
As of April 2014, schematics for the 237-0255-00 DMD controller board (primarily surface mount components) are no longer available from Stern's website. 
 

[[File:SurfaceMountFailedSolderJoints.jpg|thumb|left|300px|A fractured solder joint (circled) on this board prevented the "power on" LED from ever lighting.]] 
The surface mount version of this board sometimes has dubious solder connections at some of the surface mount resistors and capacitors. The picture at left shows a fractured solder joint on the resistor in series with the "power on" LED. The LED would never light. Another fractured solder joint on the same board prevented the reset pulse from the MPU board from ever reaching the on board 68B09E.
 

====Display Power Supply====
[[File:Stern WS DMD PSU.JPG|left|thumb|300px|Stern 520-5138-00 Display Power Supply]] 

This WhiteStar game system high voltage power supply (for displays) is an evolution from the larger Data East power supply. The high voltage section of this board is nearly identical to the high voltage section of Data East power supplies 520-5047-01 and 520-5047-02. Of course, those earlier Data East power supply boards regulate and supply more than display high voltages (i.e. 5VDC). As such, the WhiteStar board could be made more compact while using almost identical parts.
 

====128 x 32 Dot Matrix Display====
All Sega and Stern White Star games make use of a 128 x 32 "standard" dot matrix display.
 

====White Star Manufacturing Quality====
[[File:WhiteStarFactoryUpdate.jpg|300px|left|thumb|Factory updates to the Sega/Stern White Star MPU.]]
[[File:WhiteStarMPUSolderSideFactoryMod.jpg|300px|right|thumb|Ceramic cap, 10 ohm 1/4 watt resistor, and a trace cut.]] 

Generally, White Star boards are manufactured quite well. The traces are very fine, making alkaline damage repair difficult. But, those batteries shouldn't be on the board, should they? The Atmel based MPU board uses a multi-layer PCB, which increases the need for clean component removal and replacement.

Pictured at left, are two factory updates to the original Sega/Stern White Star MPU (BMST2000 version). These are normal, and not "hacks".

As can be seen in the picture at right, a ceramic 100pF cap and a 10 ohm 1/4 watt resistor have been added and a trace has been severed. This modification results in the 10 ohm resistor and the cap being placed between BMST2000 "CLKOUT" signal at pin 6 and ground at pin 10.

An additional 100pF cap is placed between pin 5 "E" and 6 "!E" of U1.
 

[[File:WhiteStarU203CutAndDiode.jpg|300px|left|thumb|Another factory update to the Sega/Stern White Star MPU.]] 
Another factory update to the left of U206 involves two cuts, and the addition of a diode between D3 and R430. Again, this is not a "hack".
 

[[File:WhiteStarPCBSolderMask.jpg|300px|left|thumb|Small traces lead to some components on White Star boards, enabling better manufacturing quality.]] 
By the time White Star boards were being manufactured, improved methods of controlling solder temperature and junction temperature at the through-holes was much better understood. In the picture at left, the "spider" connections at some through-holes, allow less heat to be used to create quality solder joints.
 

===The Wire Coloring Code===
White Star games do not use color coding system. Instead, the wire color was marked accordingly in the associated documentation, (ie. a green wire with a brown trace is referred to as GRN-BRN, orange with violet is ORG-VIO, white is just WHT, etc.).
 

===Trough Opto Boards===
++++ Need pics of the single opto transmitter and receiver boards ++++++ 
[[File:Stern WS Trough Opto Transmitter.JPG|left|thumb|300px|Stern White Star Trough Opto Transmitter (Later Games)]]
[[File:Stern WS Trough Opto Receiver.JPG|left|thumb|300px|Stern White Star Trough Opto Receiver (Later Games)]] 
All White Star Games use trough opto boards at the location of the trough VUK which feeds the ball to the shooter lane. Earlier White Star games (Apollo 13 to Viper Night Drivin') use only a single opto above the VUK plunger. Later White Star games (Lost in Space to NASCAR / Grand Prix) use a two opto system. The lower opto serves a dual purpose. It is the opto just above the VUK plunger like earlier games, but is also designated as trough switch #4. The upper opto is designated as the "stacking opto". Its purpose is to identify when a ball inadvertently gets "stacked" above a ball located at the VUK plunger. 

To briefly summarize the operation of White Star VUK opto boards, if an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch. The components used on the opto receiver board are designed to do as such. 

The transmitter side is simply an ultra-red LED with a current limiting resistor. The receiving opto is the same style ultra-red LED, and is able to detect the light wavelength emitted from the transmitting LED. By using discrete components on the receiving side, the appropriate signal is sent to the CPU via the switch matrix return (row). When LEDs are paired together in this type of fashion, the receiving LED emits a very small amount of voltage, when the proper light wavelength is present. By employing such a design, failure on the receiver opto side is more common. 

This particular system is contrary to how Bally / Williams WPC CPUs handle opto pairs. Equally, WPC games employ infrared (IR) opto switch pairs. If interested in learning the theory of operations for the White Star opto trough upkicker boards, please consult the manual. Sega / Stern have included some excellent, detailed, technical documentation within their manuals. 

As of April 2014, schematics and troubleshooting info for the trough upkicker dual opto boards are no longer available from Stern's website.

Once significant source of trouble with these trough boards is fractured header solder joints. 

===Magnet Processor Board===
[[File:Sega mag driver board.jpg|300px|thumb|left|Sega 520-5143-00 Magnet Processor Board]] 
Only two Sega games used this style of magnet processor board - Twister and Goldeneye. When U1 for Twister is installed in the board, the board's part number is 520-5143-01. The part number for the board when U1 is written for Goldeneye is 520-5143-02. Difference between the board used on each game is the different custom PIC / GAL chip used at position U1 and the Goldeneye board has R10, R11, R12, R13, D11 and D12 stuffed. This is not always the case with boards for Twister.
 

===Flippers===
[[File:Stern Flipper Assy.JPG|left|thumb|300px|Typical White Star Left Flipper Assembly (Monopoly)]] 
All Sega / Stern White Star flipper assemblies are solid state controlled. Apollo 13 and Goldeneye are the only two White Star games which use a separate solid state flipper control board located in the game's lower cabinet. Starting with Twister, the flipper board was abandoned, and circuitry for the flippers was solely controlled by the FETs on the power driver board. 

Please note that the adjacent pic of the White Star flipper assembly has a Williams flipper link / plunger installed.

The drive circuit for White Star games is different than traditional flippers. The flipper coil is single-wound. There is no "hold" winding, just a single "kick" winding. Because the flipper will get hot if the kick winding runs continuously, after the initial upstroke, the computer continuously cycles the coil on so that it stays up. According to the manual, the flipper is pulsed about 1/12 of the time.

The flipper coil must have a snubbing diode.

A normally closed EOS switch is present. The purpose of the EOS switch is to detect when a fast-moving ball has forced the flipper down ("foldback"). Unlike a traditional or Fliptronic mechanism, the EOS switch is not used to detect end of stroke. That is, the EOS switch closing does not cause a switch from "kick" to "hold". If the flipper is supposed to be up, and the EOS switch opens, the game will re-energize the flipper coil. This helps with some features, particularly "laser" kickers that fire the ball into the flippers. The EOS switch should be present for improved play, but if it's broken, the flipper will work for the most part. However, in some instances, a flipper with a broken or missing EOS switch may be noticeably weaker. If a flipper seems weak or lethargic, the flipper mechanisms have been rebuilt, and the EOS switch is broken, try replacement of the EOS switch first before considering other options.
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
Solid state pinball machines typically have a built in system for audits and adjustments. All White Star based machines use a system called "Portals". The Portals interface is a carry over from the last two Sega games (Baywatch and Batman Forever) which used the original Data East board set.

====Portals (Coin Door Test Buttons)====
[[File:Stern white star coin door inside.JPG|300px|thumb|left|The Portals control panel used on most White Star games (Monopoly)]] 
The Portals system has a very user friendly, simple navigation system. Unlike previous Data East / Sega games, having to scroll through all of the audits and adjustments is a thing of the past. Diagnostic testing (including game specific assembly tests), audits, and adjustments can all be quickly accessed via the initial display menu graphical interface. The 3-button control panel (in most cases, except some earlier White Star games) used to access Portals is located on the coin door.
 

<center>

<gallery widths=300px heights=120px perrow=3 caption="DMD Screens during Various Tests in Portals ">
File:Stern WS test switch.JPG|<center>Switch test (similar to switch edge test in Williams speak)</center>
File:Stern WS test active switch.JPG|<center>Active switch test (similar to switch level test in Williams speak)</center>
File:Stern WS test ded switch.JPG|<center>Dedicated switch test</center>
File:Stern WS test lamp options.JPG|<center>Very flexible lamp test options</center>
File:Stern WS test single coil.JPG|<center>Coil test</center>
File:Stern WS test trough full.JPG|<center>Trough clear, but equally a good test for the trough and shooter lane switches</center>
File:Stern WS test trough 3 in trough 1 shooter.JPG|<center>Advancing through trough clear</center>
</gallery>
</center>

=====Setting Free Play=====
 

===Coin Door Switches===
[[File:Stern coin door buttons.JPG|300px|left|thumb|Coin door Switches Located Inside a White Star Game (Monopoly)]] 
Most White Star games have two switches located on a bracket inside the coin door (hinge side). The upper switch is the memory protect switch. This switch is used so that nothing can be written to the memory, unless the coin door is open. The memory protect switch is not part of the switch matrix, nor is it one of the dedicated switches. Although it does connect to the CPU / Sound board via the same connector as the dedicated switches, its state is processed by a different chip (U213) versus the dedicated switches (U206). 

The lower switch is an interlock style "kill" switch. This kill switch is used to kill all power to the solenoids, when the coin door is opened. Since it is an interlock style switch, it can either be depressed (when the coin door is closed), or it can be extended outward to turn the switch on. To extend the switch to the on position when the coin door is open, grasp the switch, and gently pull it out to the lock position. 

The kill switch is a double pole switch. Wiring to one pole of the kill switch is BLK-YEL and BLK-YEL, while the other is RED-WHT to WHT-RED (yes, the colors do not match!)
 

== Problems and Solutions ==

=== Power Problems ===
===Fuse Table===
[[File:WhiteStarFuseTable.jpg|400px|left|thumb|The typical fuse table. This table appeared in the Stern Sopranos manual.]] 

=== MPU boot issues ===

Damage resulting from alkaline corrosion is the most prominent reason for the MPU to fail to boot.

If the GI lamps are blinking at about a 1Hz rate, this means that the MPU is not booting and that the I/O Driver board is sending a reset pulse to the 68B09E on the CPU/Sound board.

The following can be examined:

*Alkaline corrosion
*Inter-board ribbon cable fault inhibiting the reset of the CPU/Sound board watchdog timer DS1232. The timer is reset via signal DRV0, a lamp matrix signal.
*Failed ROM. Note that the ICs on WhiteStar CPU/Sound boards are ALL installed notch down. Installing a ROM upsidedown and powering on immediately destroys the ROM.

==== Relocating the Battery from the MPU board ====
[[File:WhiteStarAlkalineDamage.jpg|300px|thumb|left|The aftermath of batteries which leaked. This board is beyond repair, and good only for salvage parts.]]
Relocating the 3xAA batteries off the MPU board or installing other alternatives for memory retention is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. 

One option is to install a remote battery holder, and place the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) components of the MPU board. Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually. 

Another option is to install a memory capacitor. This method is considered to be better than a remote battery holder, because memory capacitors are not prone to leakage like alkaline batteries. The only drawback is that the memory capacitor has to be properly recharged to be effective. If a game has the potential of sitting dormate without being turned on for extended periods (typically months), the memory capacitor may not hold the memory. 

A third option is to install a lithium battery with a battery holder. Lithium batteries are much less likely to leak than alkaline batteries, and they do not need to be recharged.

Whatever you do, GET THE BATTERIES OFF THE BOARD! It's not a matter of if they will leak, it's a matter of when. WhiteStar boards are pricey to replace, and repair is difficult/expensive/even impossible due to the very fine traces used on the board. 

[[File:WhiteStarRemoteBatteryHolderAnnotated.jpg|300px|thumb|left|A White Star MPU Board with Remote Battery Pack Connected. The Positive (+) terminal is circled. D200 and D201 are highlighted inside the rectangle. Note that the battery installation date is recorded with a Sharpie. Also note the long wires, allowing the holder to hang well below the backbox boards, another precaution for leaky batteries.]] 
Adding a connector between the battery pack and the MPU board is a good idea. In doing this, the battery pack can easily be removed from the MPU board. Plus, if the batteries are forgotten, and do leak, the MPU board may not have to be removed to add another battery pack. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is available, a jumper can be soldered in the first battery position. Likewise, a diode can be placed in this position instead. Using a diode instead of a jumper will prevent the batteries from being charged and 'cooked' by the game if blocking diode D201 on the MPU board fails. Keep in mind that a second (redundant) diode added to the circuit will reduce the backup voltage to the RAM memory by .5 to .7 volts. Install a 1n4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the (+) terminal marking on the MPU board, and away from the battery pack. 

On the MPU, solder the battery cables: positive (red wire) to the "+" pad and ground (black wire) to the "-" pad.

Since the MPU board is already out, another good practice is to check the D201 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. Alkaline batteries do not like being charged. They will heat up, and fail rather quickly. In worse cases, the new batteries can even leak or explode if charged. Testing the D201 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D201 diode with a 1N5817 (a 1N4004 will work in a pinch), or add a redundant 1N4004 to the battery pack. Once again, if a second (redundant) diode is added to the circuit, it will reduce the backup voltage to the RAM memory by .5 to .7 volts 

Testing the D200 diode is a good idea too. The D200 (1N5817) diode is used to keep the backup batteries from powering the complete MPU board when the power is off. A symptom of a failed D200 diode are batteries which deplete rapidly.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the '''VBATT''' test point on MPU board. All battery packs are pretty cheaply made, and failures "out of the box" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:White Star Mem Cap.JPG|300px|thumb|left|Installation of a Memory Capacitor]]
A memory capacitor is a great choice for memory retention, provided that the game will be turned on more frequently than not. If the game will not be turned on for several months, the memory cap may not stay charged. In turn, the memory may not be retained. 

It is recommended to use a 1F (Farad) 5.5v memory capacitor. The lead centers on a common, button memory cap are shorter than the "+" and "-" through holes where the factory battery holder was installed. To overcome this, solder a short wire onto the negative lead of the cap. Then, bend the lead at a 90 degree angle, so it is now parallel to the bottom of the memory cap. Place the positive lead of the memory cap into the "+" of the board, and then place the wire from the negative lead into the "-" of the board. Solder both leads in place. 

Please note that when using a memory cap, the D201 diode must be removed (or jumped), and a 0 ohm jumper or a 100 ohm resistor (or similar value) should be installed. This purpose of removing the D201 diode is so the memory cap can be properly charged when the game is on.
 

==== Repairing Alkaline Corrosion ====
[[File:WhiteStarInsidiuosCorrosion.jpg|300px|right|thumb|Corrosion can hide in many hard to find places.]]
Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the batteries are mounted on the top of the board with plenty of board beneath it for the corrosion to leach onto. Components well below the battery holder are often damaged.

Remember, battery corrosion is alkaline. Harkening back to the dim and distant past, remember your Chemistry 101. Alkaline is neutralized with acid. Most commonly used is vinegar, since it is an acid. Diluting the vinegar to half strength by adding an equal amount of water (50/50) is a good idea to prevent adverse impact to adjacent areas of the board.

[[File:WhitStarAlkalineCorrosion-1.jpg|300px|left|thumb|This MPU sustained alkaline damage. Sockets for the 68B09E processor and the 6264 RAM have been removed.]]
[[File:WhitStarAlkalineCorrosion-2.jpg|300px|right|thumb|More components removed, the alkaline damaged traces sanded, and the damaged area treated with 50/50 vinegar and water.]] 
Argh! The MPU pictured at left has sustained alkaline damage. In this case, the damage was repairable. Most of the time, alkaline damage to White Star MPUs is more substantial and beyond economical repair.
 

[[File:WhitStarAlkalineCorrosion-3.jpg|300px|left|thumb|Bare copper traces tinned.]]
[[File:WhitStarAlkalineCorrosion-4.jpg|300px|right|thumb|All components (or sockets) reinstalled, and nearly ready for test.]] 
The completed board shown on the right took a few hours to cleanup, repair, verify, and game test.
 

[[File:StarShipTroopersMPU.jpg ‎|1100px|center|thumb|A StarShip Troopers MPU, with widespread alkaline corrosion abated professionally.]]
[[File:WhiteStarComponentLayout.jpg|1100px|center|thumb|Components in WhiteStar Corrosion Area. Click to enlarge. Note: "104" refers to .1uf ceramic cap, 470 refers to 470pf cap.]]

===== Continuity Chart of Pin Outs in Battery Damaged Area =====
Just below the battery holder, the CPU EPROM and RAM both reside. Both of these chips and their sockets are susceptible to battery damage. Provided that the alkali damage breached the chip sockets, it is always best to check continuity on the new work performed. Below is a chart of the pin outs between the RAM (U212), EPROM (U210), and CPU (U209) chip. This chart will hopefully come in handy should repair of this area is necessary.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Signal
!68B09E Pin (U209)
!ROM Pin (U210)
!RAM Pin (U212)
!PAL Pin (U213)
!Other
|-
| Vcc ||7||32||28||20||
|-
| GND ||1 & 39||16||14||10||
|-
| A0 ||8||12||10||||
|-
| A1 ||9||11||9||||
|-
| A2 ||10||10||8||||
|-
| A3 ||11||9||7||||
|-
| A4 ||12||8||6||||
|-
| A5 ||13||7||5||||
|-
| A6 ||14||6||4||||
|-
| A7 ||15||5||3||||
|-
| A8 ||16||27||25||||
|-
| A9 ||17||26||24||16||
|-
| A10 ||18||23||21||15||
|-
| A11 ||19||25||23||8||
|-
| A12 ||20||4||2||9||
|-
| A13 ||21||28||26||3||
|-
| A14 ||22||29||---||2||U211-2 (XA0)
|-
| A15 ||23||3||---||1||U211-5 (XA1)
|-
| A16 ||31||13||11||||U211-6(XA2)
|-
| A17 ||31||13||11||||U211-9 (XA3)
|-
| A18 ||31||13||11||||U211-12 (XA4) - Prior to rev. E boards
|-
| D0 ||31||13||11||||
|-
| D1 ||30||14||12||||
|-
| D2 ||29||15||13||||
|-
| D3 ||28||17||15||||
|-
| D4 ||27||18||16||||
|-
| D5 ||26||19||17||||
|-
| D6 ||25||20||18||||
|-
| D7 ||24||21||19||||
|-
| /ROMCS ||---||22 (BSMT2000) 24 (Atmel)||---||19||
|-
| /RAMCS ||---||---||20||18||
|-
| /E ||---||24 (BSMT2000) 22 (Atmel)||22||4||U1-6
|-
| /CS ||---||---||26||||Q9-1 - rev. D or JP1 (8K) - rev. E
|-
| R/W ||32||---||27||7||
|}

 

==== Connecting a logic probe to the MPU ====
[[File:WhiteStarConnectingALogicProbe.jpg‎|300px|thumb|left|Connecting a logic probe to a Sega/Stern White Star MPU]]
[[File:WhiteStarModifiedConnectingALogicProbe.jpg‎|300px|thumb|right|Connecting a logic probe to a Stern White Star (Modified) MPU]] 
Connecting a logic probe to a Sega/Stern White Star board set (left) is simple. 
Both 5V and Ground test points are made available on the MPU board.

Connecting a logic probe to a Stern White Star (modified) board set (right) is simple too, but a 5V connection point isn't provided. 
Connect the positive lead of your logic probe to either side of the inductor labeled FB1.
 

==== Using a PC Power Supply For Bench Testing ====

===Low 5VDC and Game Resets===
Some symptoms of a game which repeatedly resets upon boot up are:

#General illumination lamps will repeatedly flash on and off (the GI relay can be heard clicking on / off).
#The DMD will display the initial boot screen, show the display ROM revision number, go blank, and then repeat this process.
#The sound board (depending on the age of the game) may only emit a "blip" sound or a shorter than usual initial sound clip.

In some of the above instances, the DMD display may or may not light up at all. 

The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer. 

U413, which is located on the CPU / sound board next to the reset button, is a [https://datasheets.maximintegrated.com/en/ds/DS1232.pdf Dallas Maxim DS1232] monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC. 

If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. Another location to measure the +5VDC is right on the metal casing of the LM338K regulator (U19), If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338K regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto transmitter board may be at fault. 

Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. The +5V test point on the CPU / sound board is located just to the left of the 6809EP CPU chip (U209) on the board. If the voltage drastically differs between the measurement of the I/O Power Driver Board and the CPU / sound board, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board. 

==== DS1232 Voltage Watchdog ====
[[File:WhitestarDS1232Pin3Clipped.jpg|left|thumb|300px|While this looks to be an error, it's actually a factory modification to the DS1232 reset generator. While this part is on the CPU/Sound board, there is an identical part on the driver board, which will have pin 3 clipped also. On the CPU pin 2 (Time Delay Set) might also be clipped. Pin 2 and 3 are left unconnected from the factory on the WhiteStar (modified) CPU/Sound board.]]
Both the WhiteStar MPU and Driver boards employ a DS1232 voltage watchdog. From the Sega and Stern factory, pin 3 is almost always clipped. Pin 3 is used to select the voltage tolerance the chip is to enforce.

A discussion regarding the proper connection of pin 3 was offered by John Robertson on rec.games.pinball, and is copied below.

Begin discussion...

You read it here (rec.games.pinball) first!

Looking into a problem with our Roller Coaster Tycoon where the game
would cut out the lights and coils for up to a second at random
intervals. This would happen perhaps once or twice every day or two.

Digging into the game I noticed that the Dallas supervisor chip used in
both the original Stern and the Rottendog replacement Driver Board both
left pin 3 (LOP) floating. Now this pin is there to select the Vcc
tolerance - if grounded it is 5% and if tied to Vcc it is 10%. However
the schematics now show pin 3 as floating.

Sega Service Bulletin SB112 (June 7, 1999) had recommended cutting pin 3
(to floating) on both Dallas DS1232s (MPU & Driver PCBs) where the
factory (at that time) had connected pin 3 to Gnd (5%). Sega, then Stern
continued this practice of either cutting or leaving pin 3 floating.
Rottendog also did this on their replacement board.

http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf

I was curious what would happen and if this idea of cutting the leg or
leaving it floating was recommended by Dallas. So I pulled up both the
original Dallas documents and the Maxim Application Note and in neither
case did they suggest that pin 3 should be floating - no connection.They
said it was to be connected to either Gnd or Vcc.

https://datasheets.maximintegrated.com/en/ds/MAX1232.pdf

https://pdfserv.maximintegrated.com/en/an/AN581.pdf

I then asked Maxim (who now make Dallas Semi chips) to comment on what
happens when pin 3 is floating - they replied today (Nov 25, 2019):

Thank you for contacting us.

It is not recommended to leave the TOL pin open since it is a digital
input and noise can make it oscillate, there is no internal pulling
resistor, so please do indeed connect it to GND or Vcc.

Regards,
Javier Monsalve
Maxim Applications

We had already tied pin 3 to Vcc (+5) as of Nov 23, 2019 to check my
assumption that floating was wrong, and the intermittent cutting out
problems had indeed disappeared!

The game has been running for days now with no hiccups and we shall be
leaving it running at least one more day before sending it to its new
home. We are monitoring the Vcc with a Mooshimeter logging 5V, to see if
Vcc drops below any reasonable threshold and a Heathkit logic probe
monitoring the R (pin 5) of the DS1232 as the Heathkit logic probe
stores momentary state changes (turns on a 'memory' LED).

Therefore, based on our tests, and the advice from Maxim, the
manufacturer of the DS1232 IC Supervisor chip, we can now say that you
need to tie pin 3 of the DS1232 to Vcc! Do NOT leave it floating as per
Sega Service Bulletin SB112!

Hope this helps!

John :-#)#
 

[[File:RottenDogDS1232SolderBridge.jpg|left|thumb|300px|An (probably) intentionally created solder bridge on a RottenDog power/driver board, bridging pins 3 and 4 on the DS1232 voltage watchdog, selecting 5% (4.75VDC) tolerance.]] 
RottenDog WhiteStar power/driver boards may have a solder bridge across pins 3 and 4 of the DS1232 voltage watchdog. This is done to prevent pin 3 from "floating" and instead actively select the watchdog voltage.

Quoting Ed from Great Plains Electronics on PinSide...

It appears pin 3 (voltage tolerance pin) was left floating on their (RottenDog) design. That input is supposed to be tied high (reset at 4.5V or 10% VCC tolerance) or tied low (reset at 4.75V or 5% VCC tolerance) and should never be left floating. Adding the jumper from pins 3 to 4 selects the 5% tolerance. If the 5V line dips below 4.75V then your board will reset (which is what it is supposed to do with that setting).

Jumpering pin 3 to pin 8 (5VDC) selects the 10% tolerance.
 

[[File:DS1232MPU.jpg ‎|left|thumb|300px|The MPU DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
[[File:DS1232Driver.jpg ‎|right|thumb|300px|The Driver board DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
In these two images, the DS1232 voltage watchdog, pin 3, has been tied to a convenient source of 5VDC, selecting 10% (4.50VDC) tolerance.
 

[[File:WhiteStarModifiedDS1232.jpg ‎‎|left|thumb|300px|The DS1232 on a WhiteStar (modified) MPU, and connection that can be made.]] 
Some (if not all) WhiteStar (modified) MPUs leave pin 3 of the DS1232 floating. A trace from pin 3 leads to a through-hole for an unstuffed part. This through-hole can be exploited by adding a jumper as indicated in the picture at left. Installing this jumper configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance.
 

[[File:WhiteStarDriverRevGDS1232Connection.jpg ‎ ‎‎|left|thumb|300px|The DS1232 on a WhiteStar Revision G Driver Board, and connection that can be made to 5VDC, selectiong 10% tolerance or 4.5VDC.]] 
Revision G of the WhiteStar Power/Driver board leaves pin 3 floating even though R257 is provided to jumper the pin to ground. A better option is to jumper pin 3 to 5VDC which configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance. An easy method to achieve this is shown at left. This method uses the available through hole at R257.
 

==== Poor or Damaged Sockets Cause Reset ====
[[File:WhiteStarCrappySocketAnnotated.jpg‎|300px|thumb|left|A damaged EPROM socket from a Sega/Stern White Star MPU]] 
A damaged socket for either the game ROM or the 6264 RAM can cause a game to continually reset. This happens because the CPU can not fetch and execute instructions from the game ROM, or it is unable to read/write data to/from the RAM correctly. A simple replacement of damaged OEM sockets sometimes corrects a reset issue.
 

====Game Resets with DMD Controller Board Connected====
This may be a bit of an anomaly, but it is worth mentioning. If when the DMD controller board is connected without the data line ribbon cables, and the game continues to reset, replacement of BRDG21 may be required. 

In one particular instance, a game was resetting continually with only the +5v / ground connection connected to the DMD controller board. If the board was not connected, the driver board would output ~+5VDC. If the DMD controller board was connected, the driver board's logic line would dip down to around +4.85VDC. Logically speaking, this type of symptom somewhat points to the DMD controller board having issue. However, the end result was replacement of BRDG21 per Stern tech support. 

It is worth mentioning that the bridge rectifier did test correctly (using a DMM in diode test) both in circuit and out of circuit, but these tests were conducted while the bridge was not under load. 

===Solenoid/Flasher, and Controlled Lamp problems all at the same time===
[[File:CorrodedWhiteStarHeaderPinsCropped.jpg|300px|thumb|right|Corrosion on driver board header J1, prevented data bus signals from reaching the drive buffer chips. Image courtesy of PinSider JamesH007]] 
If the game is experiencing issues with multiple devices (coils, flashers, controlled lamps) that are controlled by the driver board, and those devices are "separated by 8 bits", there is a good chance that the data bus that connects to each of the 74HCT273s driver chips on the driver board has lost continuity somewhere between the associated MPU board dual row connector and the driver chips.

This can include:
*the dual row header on the MPU board
*the ribbon that connects the MPU and driver board
*the dual row header on the driver board
*the traces leading from the dual row header on the driver board to the 74HCT273s

The image at right shows a corroded connector which led to inoperative coils driven by Q3, Q11, Q19 and Q27 (note the gap between these parts is 8 transistors, the width of the data bus).
 

===Solenoid problems===

====Game Notes====
*NASCAR solenoid test swaps the order of output for coils 25 and 26. While the display calls out coils 25 and 26 correctly, in fact coils 26 and then 25 fire.

[[File:NASCAR-1.jpg‎|300px|thumb|left|NASCAR shooter lane switch with wireform correctly in place.]]
[[File:NASCAR-2.jpg‎|300px|thumb|right|NASCAR shooter lane switch with wireform bent/stuck and switch closed.]] 
Stern NASCAR, and possibly other games, use a switch in the shooter lane to detect the presence of a ball. If the switch is closed, and the auto-launcher coil fires to launch the ball, and the game doesn't detect that the switch has opened after firing the shooter lane auto-launcher, then the game assumes that the auto-launcher has malfunctioned in some way, and reports an error on the DMD.
 

====Testing MOSFETs and TIPs====
[[File:IO_test_points.jpg‎|300px|thumb|left|Driver Test Points TPL1 above Q16 (left) and TPL3 above R302 (right) are used to fire the transistors on the driver board.]] 

The Sega/Stern I/O Power Driver Board contains 32 driver transistors on the bottom right of the board. Transistors Q1-Q16 are MOSFETs – either 20N10Ls or P22NEs. These are used to drive high current coils like the flippers and other heavy loads. These are connected to devices through J8 and J9. Transistors Q17-Q32 are TIP 122s and are used for driving low power solenoids such as flash lamps. These are connected to devices through J6 and J7. 

All of these drivers are computer controlled directly from the CPU board through a flip-flop on the driver board. Q1-Q8 are controlled through U1 on the driver board, Q9-Q16 are controlled through U2, Q17-Q24 are controlled through U3 and Q25-Q32 are controlled through U4. Each one of these chips is selected by the address decoder at U204. There is another address decoder at U205 and both of these decoders must be working properly for the I/O board to function. 

It is possible to test the driver transistor and the solenoid in the circuit from the driver board. Above Q16 on the driver board is a test point marked “TPL1 FET”. Not a lot of people know what this is for. Per the manual: “This will apply 3.4v to the gate of the MOSFET transistor thus switching it on.” You’ll notice that the bank of resistors from R1 to R16 have a white stripe on one side closest to the MOSFETs. By using a jumper wire from TPL1 to the lug of each resistor in the white band, you can fire the coil associated with that resistor/MOSFET. Each resistor number corresponds with the same MOSFET number. So R1 fires Q1, R2 fires Q2, etc, etc. TPL1 is for testing all the FETs from Q1 to Q16. 

If you look in that same photo above R302, you will notice “TIP TPL3”. This serves the same purpose as TPL1 except for the TIP transistors on the driver board Q17-Q32. By jumping from TPL3 to the leg of the resistor in the white band, you can test each of the TIP122s and their associated circuitry. This is a useful diagnostic step if the machine will not fire a coil in self-test or during a game. If you can fire the transistor with this test, you know the problem is with the computer control circuitry for the solenoids. However, if it doesn’t fire, it could be a problem with the transistor or the associated components in that solenoid circuit. 

If one of Q1-Q16 is bad, it is best to replace it with an IRL540N (see below). If one of Q17-Q32 is bad, it is best to replace it with a TIP102. 
=====Screening Error On the Board=====
You might notice in the photo (prior section) that the white stripe is on the lower leg closest to the transistors of R1-16 and R25-32, but there is no white stripe on R17-24. Instead the stripe is on the lower leg of the resistors R200-R207. This is a screening error on the board but electrically match to the correct legs of resistors R17-24. As an example, if you want to test Q17, touch the leg of resistor R200 that’s in the white strip and Q17 should fire. The same holds true for R201/Q18, R202/Q19, etc etc. 

====Can an IRF540 replace a P20N10L, P22NE10L or an IRL540?====
[[File:IRL540vsIRF540.jpg‎|300px|thumb|left|Danger Will Robinson...the IRF540 installed at Q6 shown above, is the wrong part. The original 22NE10L should be replaced with an IRL540, like the one to it's immediate right.]] 
No.

The White Star driver board first used STP20N10L FETs to drive high current circuits, like solenoids. When they were discontinued later boards used the STP22NE10L. Since the 22NE10L is obsolete and even the current replacement, the
STP40NF10L is hard to find, the IRL540 or IRL540N are the recommended replacements. If available get the IRL540N because it has a higher drain current rating of 36A.
 While the drive specs of the IRF540 seem comparable, they are not. Using an IRF540 as a substitute can cause the associated coil to lock on, toast the coil, then blow the FET. The L in all of the original parts indicate that it is a logic level FET.

Per a good friend of Pinball, Ed Krzycki, via [http://groups.google.com/group/rec.games.pinball/browse_frm/thread/de777f6eec98a687/330e0d47fde12c6f?hl=en&lnk=gst&q=irf540# RGP post]...

''Nope -- an IRF540 is not a good sub for the IRL540 or 22NE10L.''

''The "L" parts have TTL compatible gate voltages. A TTL gate has a minimum high level output voltage of about 2.4 volts. To turn on any N-channel MOSFET transistor - the Gate voltage must be sufficiently high enough as listed by the spec sheets VGS(th) voltage.''

''The IRL540 requires a Gate threshold voltage of 1 to 2 volts. A TTL part exceeds this voltage so a TTL gate's high level output would guarantee the gate would turn completely on. The IRL540 is guaranteed to have "turn on" and "turn off" voltages that are compatible with a standard TTL device.''

''The IRF540 requires a Gate threshold voltage of 2 to 4 volts. A TTL gate *might* turn this part on if the specific part being used has a threshold in the 2 to 2.4 range. If the specific part being used has a threshold closer to the 4 volt range then the MOSFET probably won't turn on properly or fully. The IRF540 *might* work or it might not work. And no guarantees that a working part would remain working if ambient temperature changes.''

''Another aspect to an IRF540: An IRL540 operates more as an on-off switch but an IRF540 does not. Depending on voltages, an IRF540 can operate as an on-off switch and can also operate anywhere in between on and off (half on) depending on input voltage. If the TTL device cannot quite drive the gate voltage high enough then the MOSFET may end up partially conducting. This can have different results depending on how much it is turned on.''

''The 22NE10L has similar characteristics to that of the IRL540 as far as gate threshold voltages.''
 

====Adding a Real Knocker to White Star Games====

Some White Star games (like Starship Troopers) are not equipped with a real, old fashioned, knocker. We all love knockers, don't we?

To add a real knocker to your White Star game, follow this procedure.
Note: in this procedure, we locate the knocker in the head, attempting to increase the knocker's impact. For cabinet installation, take advantage of the wiring already provided for the European Token Dispenser.

[[File:AddingAKnockerBigPicture.jpg|left|300px|The objective...]] 
In the picture at left, we show all the components necessary to add a knocker. The new knocker is circled, top left. We've used an in-line connector along the wiring, also circled, lower left. The power and ground connections are noted by the rectangles.
 

[[File:SSTManual.jpg|thumb|left|300px|A snippet from the Sega Starship Troopers manual showing coils, and in particular, coil 8, the European Token Dispenser.]] 
First we need note that the European Token Dispenser solenoid drive is unused in domestic (USA) games. Coil power and drive connections are wired into the game. They can be found in the cabinet bottom. We could simply connect the knocker to that connection, but in this example, we mount the knocker in the game head.
 

[[File:SolenoidPowerConnection.jpg|thumb|left|300px|Adding a wire to provide the knocker with 50V power.]] 
Here I've stuffed another wire (yellow with purple tracer) on top of the solenoid power supply at J10, pin 5. This wire will eventually be connected to the banded side of the knocker coil.
 

[[File:SolenoidGroundConnection.jpg|thumb|left|300px|Adding a wire to provide a path to ground for the knocker, typically called the solenoid drive.]] 
Here I've stuffed another wire (purple with black tracer) on top of the solenoid 8 drive connection at J8, pin 9. This wire will eventually be connected to the non-banded side of the knocker coil.
 

[[File:SegaKnockerInSitu.jpg|thumb|left|300px|The new knocker, screwed to the cabinet upper left corner...not much room there. Also add the "strike plate" to the cabinet side.]] 
Of course, you need to procure the actual knocker hardware, and connect it as shown in the prior pics. In the picture at left, we've added a Sega knocker assembly and strike plate.
 

The last thing to do is to enter the game adjustments and turn the electronic knocker sound and the European Token Dispenser settings to off. On Starship Troopers, Enter Portals, Adjustments, Sega, and then adjustment 33 (Knocker Volume - set to OFF) and adjustment 40 (European Token Dispenser - set to OFF).

That's it. Enjoy those knockers!
 

===Flasher problems===
[[File:SSTFlashers.jpg|300px|left|thumb|One of the 4 sets of 4 colored flashers on Starship Troopers.]] 
Starship Troopers, Apollo 13 and perhaps other White Star games, drives 4 flash lamps via a single TIP-122 transistor. The TIP-122 is rated for a maximum drain of 8A (and a working current of 5A) while 4 flash lamps typically have a cold resistance of under 1 ohm (0.8 ohm is typical including wire and socket resistance.) While incandescent lamps only present their minimum resistance when extinguished (they are negative-temperature coefficient devices by design) the surge drain when these lamps are lighted radically exceeds the transistor's rating and is likely to damage or destroy it over time.

These channels should be replaced with TIP-102s (15A peak drain) or replace two (or more) of the flash lamps with LEDs to bring the drain in-line with the maximum ratings of the TIP-122.
 

===Controlled lamp problems===

==== Overview of The Lamp Matrix ====

The WhiteStar lamp matrix is an 8 column, 10 row lamp matrix, powered by 18V.

Lamp matrix power is derived from 13VAC presented to the I/O Driver board at J17, pins 8 and 9, via the transformer secondary winding. The circuit is fused by F22, an 8ASB fuse. BRDG20, a 35A bridge rectifier creates the 18VDC which is then smoothed by two 15,000uf/25V filter capacitors at C201 and C202. Of interest is the combined filtering of 30,000uf matches the original lamp matrix filtering capacity of old Williams System 3 games. When lit, LED202 indicates the presence of 18VDC power.

A blown fuse at F22 probably indicates a shorted bridge at BRDG20.

[[File:WhiteStarLampMatrixComponents.jpg|300px|thumb|left|Components of the WhiteStar I/O Driver Board Lamp Matrix]] 
Lamp rows are implemented with STP19N06L or STP20NF06L FETs, controlled by the 74HCT273 at U6 on the I/O Driver Board. 39K current limiting resistors protect the 74HCT273 from sinking too much power. The 74HCT273 is strobed (enabled) via the LMPSTB which originates at U205 (a 74LS138 at U205, pin 15).

If a STP19N06L (or STP20NF06L) transistor fails, it can be replaced with an IRL530N or an IRL540N. However, using an IRL530/540 has been known to create "ghosting" or "always dimly lit" behavior in the lamp row. If the original part can be obtained, this possibility can be eliminated. An IRFnnn (i.e. IRF530) or BUZ22 can not be used as a replacement.

Lamp columns are implemented by the obsolete VN02N PENTAWATT solid state relay (5 legs). They are controlled by the 74HCT273 at U18 on the I/O Driver Board. 18VDC is "strobed" to the lamp column headers. The 74HCT273 is strobed (enabled) via the LMPDRV which originates at U205 (a 74LS138 at U205, pin 13).

A replacement for the obsolete VN02N has not been identified. In addition to the WhiteStar I/O Driver board, VN02Ns were used on Capcom driver boards.

Be sure to check the fuse clips for the controlled lights. They go bad from either metal fatigue or they crack. This causes poor, erratic, or no connection with the fuse and thus, no lights.
 

===General illumination problems===

The four general illumination (GI) strings are turned on and off via the relay on the power driver board. On the White Star board the relay is controlled via transistor Q200 and latch U206. This is more or less the same setup found in earlier Data East and Williams System 11 games where the relay is located on the power supply or PPB board. These relays seldom fail. The part number for the 24VDC relay is any of the following:

*LB2-24DP (Great Plains Electronics number)
*190-5002-00
*LY2-0-DC24
*FRL264 P024/02CK
*R14-11D10-24P

If one or more GI strings are out check fuses F24 to F27 and then connector J15. Although WhiteStar GI connectors don't burn and tarnish like early Bally/Williams WPC GI connectors, checking both the male and female connectors at J15 is worthwhile.

[[File:Sega-whitestar-pdb-gi-error.jpg|300px|left|thumb|A leaky capacitor at C32]] 
If the GI goes out during game play and turns back on when opening the door, check capacitor C32 on the power driver board. It normally has nothing to do with either the GI circuit or the relay voltage but a leaking cap can short the trace coming from Q200 to ground. In this case the relay pulls in and disconnects the GI. When you open the door the game cuts the coil power for the relay coil and the GI turns back on. This has been observed in a Twister game.

The fuse clips for the GI circuits can fail, either by cracking or by losing their springiness.
This causes poor or no contact with the fuse and intermittent or no power to the associated GI string of lamps.
 

=== Switch problems ===

==== Overview of the Switch Matrix ====

The WhiteStar switch matrix is the typical 8 by 8, 64 switch matrix. As with other switch matrix implementations, isolation diodes are used on every switch in the matrix.

Switch columns (strobes) are connected to CN5 on the top edge, left side, of the CPU/Sound board. The columns are controlled by the 74HCT273 at U203 which sequentially controls an array of 8 2N3904 transistors. These transistors switch the 5VDC, normally held high via 560 ohm pull up resistors R423 through R430, to ground.

If a switch in the matrix is closed, the ground driven through the switch column will be presented at the row associated with the column/row intersection of that switch.

Switch rows (returns) are connected to CN7 on the top edge, right side, of the CPU/Sound board. 5VDC pull up resistors (560 ohms at R401 through R408) normally hold the switch row high. However, when the ground is presented at the row header of CN7, that 5VDC is pulled to ground. The signal is compared to 5VDC by the LM339 comparators at U400 and U401 with the result presented the the 74HC245 at U205 and then read via the 68B09E's data bus.

Note that the WhiteStar LM339 comparison implementation differs from the Bally/Williams WPC implementation which also uses 5VDC as a comparison voltage (reference) but compares that 5VDC to either 12VDC (open switch) or ground (closed switch).

==== General Switch Matrix Testing ====

[[File:WhitestarSwitchTest.jpg|thumb|300px|left|Testing Whitestar CPU/Sound board switch matrix circuitry with a jumper. A diode is not necessary.]] 
Like most modern game manufacturers, Sega/Stern games employ a switch matrix. The switch matrix circuitry on the CPU/Sound board may be tested (as pictured at left) by jumpering between switch row and switch column header pins while in switch test. This works with all versions of the Whitestar CPU/Sound board.

Note that some games, that do not use the full switch matrix, will fail to report a switch closure when jumpering row and column header pins for a switch that is shown as "not used" by the game. i.e. Sopranos does not use switch column 6. While a strobe is sent out on column 6, jumpering between column 6 and any row will not return a switch closure indication in switch test.

 

==== Playfield Switch Problems ====

===== Modular Stand Up Targets =====
The following Sega games employ unique playfield "Stand Up" targets:
*Goldeneye
*Twister
*Space Jam
*Star Wars Trilogy
*The Lost World Jurassic Park
*Starship Troopers
*Viper Night Drivin'
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park
*Playboy (used behind the "Peek-A-Boo" stand up)

They are self-contained modular targets, made by Happ Controls, that are quite easy to remove or replace. The target "faces" may be purchased separately and may be interchanged easily. The unit has a self-contained diode, like all switches that are sensed via a switch matrix. It also contains a small micro-switch, that the "tail" of the target face actuates. The "Achilles Heel" of this target system is the IDC connector. As with all IDC connectors, the wires can pull out fairly easily. 

Detailed disassembly / assembly instructions can be reviewed in [http://www.pinwiki.com/wiki/images/7/76/Stern-Sb110.pdf Stern Service Bulletin 110]. 

<center>
<gallery widths=250px heights=200px perrow=3 caption="Sega Modular Targets (from Starship Troopers)">
File:SegaTargetFullyAssembled.jpg|<center>An example target. The target "faces" are interchangeable.</center>
File:SegaTargetParts.jpg|<center>"Exploded" target parts. The gray switch part must be oriented correctly. Note the integrated diode just under the micro-switch, center/bottom.</center>
File:SegaTargetIDCConnector.jpg|<center>The Achilles Heel of a Sega target...the IDC connector.</center>
File:SegaTargetDisassembly.jpg|<center>The first step to disassemble a target. Slide the rear face of the target assembly up.</center>
File:SegaTargetTestingZero.jpg|<center>Testing a closed target switch, step 1. In diode test, with the switch closed, your meter should read 0 or null.</center>
File:SegaTargetTestingDiodeDrop.jpg|<center>Testing a closed target switch, step 2. In diode test, with the switch closed, your meter should read .5 to .7, the nominal voltage drop across a diode.</center>
</gallery>
</center>
 

=====Magnetic Reed Switches=====

[[File:Placeholder.jpg|thumb|300px|left|Sega Magnetic Reed Switch (from Space Jam)]] 
Starting with Space Jam, Sega introduced magnetic reed switches. This type of switch is a sealed, non-serviceable switch. Theory of operation of the reed switch can be reviewed in [http://www.sternpinball.com/upload/downloads/sb89.pdf service bulletin 89]. Replacement part number is 180-5145-XX.
 

=====Ball Trough Switch Problems=====
[[File:White Star Trough 18 Nut.JPG|left|thumb|300px|Typical Sega ball trough assy. using 1/8" screws heads]]
[[File:White Star Trough 316 Nut.JPG|right|thumb|300px|Typical Stern ball trough assy.using 3/16" screws heads]] 
As with any sub microswitch, the switches can become sporadic or fail over time. Another thing that can happen is the switch arm can break at its pivot point. This happens with this style of switch more frequently than other styles, because the metal arm is placed between two plastic ears. With nearly every other style of sub microswitch, the arm has the metal ears which go over plastic nubs on the switch body. The correct replacement switches are 180-5119-00 roller arm switches. Over the years Sega / Stern used both 1/8" and 3/16" screw heads on the screws which secure the trough switches. At this time, it is uncertain when Sega / Stern changed the screw size. 

[[File:Xcelite 18 Nutdriver.jpg|left|thumb|300px|Xcelite 1/8" Nutdriver used to remove screws from trough switches]]
[[File:DE Ball Trough Divots.JPG|right|thumb|300px|Ball trough assembly with divots. Although it's not a White Star game, Jurassic Park is used for this example.]]
There may be other issues, which appear to act like ball trough switch failures. One of the problems is divots in the ball trough itself. After many iterations of the balls slamming into the trough over and over, divots start to develop. This divots can keep balls from rolling down the trough assembly. In turn, the balls will not be closing the proper switches in the trough. The end result is a game that "loses its mind". If the balls are not where they are expected to be in the trough, the game cannot function as intended. 

A similar issue to divots in the trough is magnitized balls. This occurs primarily in games where a magnet captures a ball and holds it for a length of time. Some examples of games with magnets that hold the ball are Apollo 13, Goldeneye, Twister, Space Jam, and X-Files. This problem typically happends when two or more balls are grouped together in the trough. They will literally be held in place and stick to the trough. This happens to the balls located furthest from the ball trough VUK. To determine if a ball or balls are magnetized, remove the lower apron, and the top bracket over the trough. Gently place a non-metallic object between the balls to see if they separate themselves.
 

For ball trough switch issues pertaining to the opto boards, see the section [[#Two_Balls_Served.2C_Continuous_Balls_Served_to_the_Shooter_Lane.2C_or_the_Trough_VUK_Fires_Repeatedly | below.]]
 

====Opto Switch Problems====
With White Star games, opto switch pair closures are analyzed by the CPU in the same manner as leaf switch pairs or normally open (NO) microswitches. When a leaf or NO microswitch closes, the end result is identified by the CPU as a valid switch closure.

[[File:Sega_X-Files_Optos.JPG|left|thumb|300px|Two sets of opto pairs installed in a Sega X-Files ]]
If an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch.

The transmitter side is an ultra-red LED with a current limiting resistor. The receiver is an identical ultra-red LED. When light from the transmitter shines on the receiver LED, a small amount of voltage is "excited" in the LED. By using discrete components on the receiver side, that small voltage is detected and the appropriate signal is sent to the CPU via the switch matrix return (row). In this design, failure on the receiver opto side is more common. The transmitter LED will be lit (and visible with the naked eye), while the receiver LED will not be lit.
 

<center>
<gallery widths=300px heights=150px perrow=3 caption="Sega/White Star Transmitter, Receiver, and Opto 'Long Hop' Board Pair, as found on Starship Troopers. Note that the ultra-red LED on the transmitter side is not lit until power is applied. The receiver side never illuminates.">
File:SegaOptoTransmitter.jpg|<center>The opto transmitter side.</center>
File:SegaOptoReceiver.jpg|<center>The opto receiver side, with accompanying electronics. The red colored LED is a diagnostic aid to indicate a detected switch closure.</center>
File:SegaOptoAlignment.jpg|<center>An opto pair. The pair must be in perfect alignment or the opto switch will operate unreliably.</center>
</gallery>
</center>
 

This particular system is different than how Bally/Williams WPC CPUs handle opto pairs. WPC games employ infrared opto pairs.

Theory of operation for these circuits is described in the manuals. Sega/Stern have included some excellent, detailed, technical documentation within their manuals. [https://www.pinwiki.com/wiki/images/9/92/Sb67.pdf Stern Service Bulletin #67] includes detailed theory of operation of these opto switches. 

=====Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly=====
Common problems with some White Star games are:
# Two balls are served to the shooter lane.
# Balls are continuously served to the shooter lane.
# The trough VUK repeatedly fires, when there are no balls above the VUK trough plunger.

The first test is to determine if the balls are sliding down the trough. If they are repeatedly magnetized they tend to stick to the side of the trough and not slide down. Replacing the balls with will fix this. There are balls available which are low magnetic, but you can also line the floor of the ball trough with a thin sheet of PETG breaking the magnetic contact.

Depending on the exact circumstances, and the era of the White Star game, one or two of these symptoms can occur. The crux of the problem is either one or both of the two trough LED opto transmitters or receivers is failing. Rarely do the components on the trough opto boards other than the red LEDs actually fail though. And in most cases, it is not the LED itself, although, there are some instances when the problem is a failing LED. It is noteworthy that the issue is more common to the opto receiver side more so than the opto transmitter side. 

[[File:Stern WS test trough 1 in trough.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough]]
[[File:Stern WS test trough vuk up one ball.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough and One Ball Stacked]]
If the any of the previously mentioned symptoms are evident, the best approach is to first put the game into "Clear Ball Trough" mode via the Portal buttons on the coin door. Consult the manual documentation for details how to enter this test. Once all of the balls are removed from the trough, no balls should display on the DMD display. If either of the two images shown to the left are displayed on the DMD, and the ball trough no longer has any balls present, there is a problem with either the transmitting or receiving opto boards.<br=clear all>

The first thing is to observe the two red opto LEDs on the transmitting board. This board is located on the backside of the ball trough. If the transmitting LEDs are lit, there probably is not a problem with them. However, this is not always necessarily the case. Secondly, inspect the opto LEDs on the receiving board. To do this, the game will have to be turned off, and the receiving opto board removed via the three screws which attach it to the trough. Look for hairline cracks around the .100" angled header pin solder joints. Likewise, inspect the solder joints around the opto LEDs. If cracks are evident in any of these locations, remove, and apply fresh solder to these connections. Reinstall the receiver board, and observe the results. Conversely, if hairline cracks are not found, or if the same symptoms are still evident after reflowing solder joints, replacement of the LED optos is suggested. 

White Star games initially used MT5000UR ultra-bright red LEDs, while later games used TLRH180P ultra-bright red LEDs for both the transmitter and receiver boards. Both styles of LEDs have become expensive and fairly difficult to source. Great Plains Electronics offers the [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] as viable replacement for either original, factory LED. The only caveat is that both the transmitter and receiver opto LEDs must be replaced in pairs to ensure proper function. 

When replacing the opto LEDs, make certain the base of the LED is placed squarely on the PCB. An LED which is poorly installed may result in sporadic switch closures. 

[[File:DE Trough Ball Lock3.JPG|300px|left|thumb|Lock Ball Assembly (from Jurassic Park - used for illustrative purposes)]] 
Please note that a "Lock Ball Assembly" was employed in the trough design on early White Star games. The lock ball assembly is a unit, which was carried over from later Data East and early Sega games. It consists of a coil mounted horizontally above the left side of the trough VUK. This assembly was later removed presumably either due to cost factors, or so this coil assignment could be used as a playfield coil feature elsewhere instead. 

If a lock ball assembly is used in the game, and trough opto failure has occured, the symptom will more than likely be that the trough VUK will fire repeatedly without a ball present above the VUK plunger.
 

=====Phantom Opto Switch Closures=====

Similar to the discussion above, "Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly", other opto pairs in the game may fail over time and become unreliable. Usually this manifests as phantom switch closures. Games like Starship Troopers that use an opto pair for both the left and right orbit shots may score the orbit shot randomly or even continuously. If the "long hop" opto assembly is removed, you may find that the opto pair registers correctly if the optos are aimed with great accuracy at one another. However, the slightest misalignment (like flexing the PCB) will cause the opto pair to register a "hit".

The correction for this is again to replace the original MT5000UR or TLRH180P ultra-bright red LEDs, with [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] LEDs from Great Plains Electronics.
 

===Display problems===
A few of the many possible display problem root causes are...
*Failure in high voltage power supply
*Failed Dot Matrix Display
*Failed ribbon cable
*Failed power connector on display driver board
*Failed 74LS374 buffer IC on the MPU board

Each possible root cause is discussed below.

==== Measuring High Voltages for the DMD Display ====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|300px|thumb|left|Testing DMD Controller voltages at the display. Note: This picture is a Williams game, but the concept is the same.]] 
To test for the voltages necessary for the DMD to operate, first open the backbox, and rest the DMD panel face down on the glass. Or, if the game has a "Showcase" style head (i.e. StarShip Troopers), swing the panel open to gain access to the HV connection to the DMD. The simplest place to test the voltages is at the display end of the power wire bundle as shown in the picture. SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you! 

The dot matrix display needs three voltages to operate, nominally -112, -100, and 62 VDC. All three voltages must be present for the display to operate correctly.

Place the black lead of the DMM under the ground braid in the game's head or use clip leads to secure the black lead to ground. Remember, you are working one-handed, so this becomes a necessity. Place the red lead of your DMM on each of the pins supplying power as shown in the picture. As long as there is a 12VDC difference between the Anode and 12VDC offset voltages, your DMD controller is providing correct voltage levels.

{| class="wikitable"
!Function
! Pin 
! Spec 
! nominal voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>-120V</center> || <center>'''-112V'''</center> ||
|-
|  12VDC Offset  || <center>2</center> || <center>-100V</center> || <center>'''-100V'''</center> ||  Must be 12V less than anode voltage. Will be about 20V less than anode voltage if display not connected
|-
|  Key || <center>3</center> || || ||
|-
|  Ground || <center>4</center> || || ||
|-
|  Ground || <center>5</center> || || ||
|-
|  5VDC || <center>6</center> || <center>5V</center> || <center>'''5V'''</center> ||
|-
|  12VDC || <center>7</center> || <center>12V</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>60V</center> || <center>'''62V'''</center> ||
|}

If the high voltages are off by more than a few volts, turn the game off, disconnect the power connector at the HV Power Supply, and test the voltages at the HV Power Supply male header pins. If the voltages return to nominal values, the zener diodes on the power supply are probably OK but the resistors and transistors around them are suspect. As shown in the table above, if HV power is not connected to the display, the nominal 12VDC offset will be about 20VDC.

Note that a failing or failed DMD display glass can drag these voltages down. Before you begin any work on the HV Power Supply board, perform the above test with the DMD display power disconnected. If the voltages return to nominal values, it's possible that your display is the culprit. Test the high voltages with a known good display to isolate the fault to either the HV Power Supply or the display panel.

Should your HV Power Supply fail, the circuit is almost identical to the circuit used by Williams in their WPC DMD Controller. Similar parts are required to rehab the Sega/Stern HV Power Supply.

As of April 2014, schematics for the HV Power Supply are no longer available on Stern's site.

====Typical Failures of High Voltage Power Supply====
[[File:Stern WS DMD PSU.JPG|right|thumb|300px|A Stern 520-5138-00 Dot Matrix High Voltage Power Supply]]

'''The nominal output voltages of this board are shown below.''' 
The voltages measured between game ground and each pin of CN2 (right side as installed in the game).
*-110V on CN2-1
*-98V on CN2-2
*+5V on CN2-6 (piped directly through from CN1-7. This was a method of minimizing connector complexity)
*+12V on CN2-7 -- 20V is supplied at CN1-6 and is regulated down to +12V by VR1, a 7812. Note: the voltage at this pin will be missing if the board isn't stuffed with the 7812. It is not known when Stern/Sega stopped stuffing this location.
*+68V on CN2-8

The fuse on the board is a 3/4 ASB fuse.

'''Common failures:'''

*Fuse blowing
*-110V missing or too low
*-98V missing or too low
*+68V missing or too low

'''Solutions:'''

A blown fuse is indicative of a failed rectifier diode at D1 or D2 (1N4004. Anything from a 1N4005 to a 1N4007 can be used too). When D1 fails, Q1 and Q3 often fail along with it. When D2 fails, Q2, Q4, and Q5 often fail along with it.

*-120V problems are often caused by a failed transistor at Q2 (MPS-A42) and/or Q4 (MJE15031). When one of the transistors fails, often the other one fails too. Replace zener diode D4 (3.9V, 1N4730), D6 (100V, 1N4764A) and D7 (13V, 1N4743A) as well.

*-100V problems are often caused by a failed transistor at Q5 (MJE15030) or zener diode D6 (100V, 1N4764A). It's best to replace both. The 2k/5W resistor on R8 might also be the problem source, mostly due to failed solder contacts.

*+60V problems are often caused by a failed transistor at Q3 (MJE15030) and/or Q1 (MPS-A92) When one of the transistors fails, often the other one fails too. Replace zener diode D3 (3.9V, 1N4730) and D5 (68V, 1N4760A) as well.

As of 2014, schematics for the display power supply board are no longer available on Stern's website.

The Data East display power section of the 520-5047-01 and 520-5047-02 boards is an almost 1:1 copy compared to the one on this board. 

==== Failed Dot Matrix Display ====

A failed Dot Matrix Display will obviously cause display problems. Once you've tested for proper voltages, swap in a known good display, and swap the suspect display into a known working game. If the suspect display doesn't work in the known working game, it's time for a new DMD display.

==== Corrosion Under Header Pins ====

[[File:DESegaSternDMDControllerCorrosion.jpg|300px|thumb|left|Corrosion under the dual row headers of a DMD Controller board]] 
Corrosion from leaky batteries, being the bane of pinball PCBs, finds it's way to many places that might not normally be suspected. Sometimes, alkaline corrosion invades the header pin carriers, as shown in the picture at left. In this case, enough of the signals between the MPU board and the DMD controller board were corrupted to prevent proper rendering on the DMD display. Cleanup via typical methods restored this board to proper operation.
 

==== Failed ribbon cable ====

The ribbon cables on Sega/Stern White Star games connecting the CPU to the display controller are particularly long and twisted. There is ample opportunity for the ribbon cable to be damaged.

You should reseat the ribbon at both ends several times to knock off accumulated corrosion. This might temporarily solve the issue.

A simple test of the ribbon cable integrity would be to reverse it, causing the conductors used within the ribbon to be "swapped". Remove the ribbon from both ends, and instead of seating it with the red stripe at pin 1, seat the ribbon with the red stripe at the opposite end from pin 1. Make sure you reverse both ends of the ribbon. If the results witnessed on the display are then different, there is a good chance you need a new ribbon cable.

Gently bending and twisting the ribbon cables may help uncover intermittent connections and a compromised cable. Don't bend/twist too vigorously as this in itself may compromise the cable.

==== Failed power connector on display driver board (CN2) ====
[[File:CN2.jpg|300px|thumb|left|The '''craptastic''' 3 pin DMD Controller power header at CN2.]] 
Sega/Stern (and even Data East) made a poor decision for the power connection to the display controller. CN2 is a .156, 3 pin connector, which connects 5VDC and Ground to the display controller. The connector can be installed upside-down and reverse the 5VDC and Ground connections. This may kill the ROM chip and other chips on the board.

The solder joints for these header pins fracture often, or the pins in the female housing lose their grip (and hence connection). It is good practice to repin both sides of this connection, using crimp-on TriFurcon pins in the female housing.
 

==== Blank Display After "Splash Screen" Or Unusual Messages (Failed 74HCT273 buffer IC on the MPU board) ====

[[File:BadSchematicTableIndex.jpg|300px|thumb|left|One manifestation of a failed U201 or an open between U201 and the plasma display connector. Image courtesy of Chris Hibler.]]
The 74HCT273 at U201 on the CPU board buffers the output to the display controller via the ribbon cable. Should this IC fail, incorrect or no data will reach the display controller. Most of the time, this results in only the "splash screen" appearing which is displayed by the DMD controller on it's own, or in rare instances, the odd displays shown at left. First an over-scaled "Location ID:" image is displayed then "Bad Schematic Table Index!". This particular failure was caused by a corroded trace between U201 pin 2 and the via just northwest of pin 2. However, the same message may be displayed any time that the data path between U201 and the DMD Controller fails (i.e. poor header connections, failed ribbon cable).

U201 can be tested with a DMM following the process described [[General#Testing_an_integrated_circuit| here]].
 

====Display Issues Caused by Mismatched Game and Display ROMs====
[[File:WhiteStarEffectF7.jpg|300px|thumb|left|This message appears when the display controller software can't correctly decode display "calls" made by the MPU. Note that hexadecimal numbers other than "F7" may be displayed. Image courtesy of Chris Hibler.]]
Over the course of a game's manufacturing run, and even post production, game and display software was updated. It is important to ensure that the game ROM version is compatible with the display ROM version. Newer versions of the game code may request a display routine from the display controller that the display controller can not make sense of. When this happens, the display controller will display "Effect NN", where "NN" is the hexadecimal number of the display routine received.

Note that a less likely failure of IC U17 (a 74LS245) on the display controller board, which buffers inputs from the MPU, can cause the same or similar behavior. Corrosion on the ribbon header pins (both ends) or a faulty ribbon cable are other possible reasons for this message.
 

===Sound problems===

Before going any further, check all of the basics in the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section. 

'''Basic operation (simplified) of the White Star CPU/Sound board audio part:'''
The main CPU (U200) makes sound calls to the sound CPU (U6) which instructs the BSMT to play a certain sound. The BSMT fetches the required data (sound sample) from the ROM memory (U17-U21-U36-U37) and feeds the 16-bits wide parallel data to a conversion circuit which makes it serial data (shift register, U23-U24). The serial data is fed into a DAC (U26, Digital to Analogue Converter) that outputs to a pre-amplifier (U30, OPAMP). The output from the pre-amplifier is fed into the TDA2030A amplifiers at U101/U102 and sometimes U100 (some boards have 3 amplifiers, one for each speaker) and from there the audio signal goes to the speakers.

[[File:XilinxCPLD.jpg | thumb | right | 300px| The XC9572XLT Complex Programmable Logic Device. The yellow paint spot indicates that it has been programmed.]] 
The White Star (modified) version of the MPU board replaces almost all of the prior version's sound circuitry with 3 surface mount ICs.
*Xilinx CPLD at U414 (XC9572XLTQFP, T indicating the 100-pin version, QFP indicating Quad Flat Pack)
*Atmel RISC processor at U402 (AT91R40008)
*Atmel flash memory at U8 (AT49BV162AT)

The Xilinx CPDL ([https://en.wikipedia.org/wiki/Complex_programmable_logic_device Complex Programmable Logic Device]) is programmed by Stern (or it's board manufacturer) via the [https://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] connector on the board.

The Atmel RISC processor ([https://en.wikipedia.org/wiki/Reduced_instruction_set_computing Reduced Instruction Set Computing]) replaces the 68B09EP of the prior board.

The Flash Memory contains the Sound Operating System. The correct version of the sound operating system my be "flashed" into the memory.
LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin #157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another). In April, 2016, "Chas" at Stern Pinball noted that sound operating system 8 (O/S 8) is backwards compatible with all WhiteStar (modified) games. It may even work with sound ROMs predating the WhiteStar (modified) board. However, there are known compatibility issues with early WhiteStar Sega games like StarShip Troopers.

The sound section of both board versions is quite reliable. The failure occuring most is a failed TDA2030A amplifier. If a sound problem can be isolated to one of the three fine pitch surface mount ICs on the WhiteStar (modified) board, the only option known as of April, 2016 is to return the board to Stern for repair. Stern does carry the parts necessary, but removal and replacement of such fine pitch parts is above the capability of most pinball hobbyists.

'''Sound missing from one of the speakers:'''
Possible failed TDA2030A amplifier.

'''No sound at all:'''
Check the voltages on the board. On the DC input connector CN2 there should be approx. +12V DC between pin 2 (ground) and pin 6 (+12V) and -12V between pin 2 (ground) and pin 3 (-12V), these voltages come from the Power Supply Board. On the board itself are two voltage regulators to convert the +12V and -12V to +5V and -5V for the pre-amplifiers, check these voltages by measuring between the ground (GND test point) and U30 pin 8 for +5V, U30 pin 4 for -5V.

Other causes of no sound at all are the U7 game ROM being corrupted or improperly seated. You can re-seat this ROM and it often solves the issue. If any of the voice ROMs (U17, U21, U36, U37) are corrupted or improperly seated, the sound will still work but will be corrupted or have intermittent issues such as scratchy sounds or improper sounds at specific times.

An incorrectly jumpered or installed RAM chip can also cause no sound. JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket).

Finally, if you have no sound at all, check that you have the correct sound board. Some operators may have swapped the Atmel based board with a BSMT2000 based board board for the older series White Star games. The Atmel based board will work in all White Star systems although some sounds may not be rendered correctly or at all. The BSMT2000 based board will work but will present no sound at all in all games newer than lord of the rings (2003).

'''Samples playing randomly'''
This happens on Whitestar (modified) CPU boards that emulate the BSMT2000 (which Stern could not source cheaply enough at the time). Reflashing the sound operating system firmware per Stern [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin 157] is recommended.

'''Sound is distorted'''
If the sound is distorted, a prime suspect is the TDA1543 (U26) chip. This sounds as if the volume is very over modulated and are “clipped”. Be sure to use the TDA1543 version and NOT the TDA1543A. The TDA1543A uses another protocol (Japanese). If the sound is distorted at master volume levels below 4, see the [http://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#Loud_Hum_and_.2F_or_Distortion_at_Low_Sound_Levels "Loud Hum and/or Distortion at Low Sound Levels"] section below.

'''Sound cuts out at the exact same point in a clip every time'''
If the sound consistently cuts out, or volume is lowered, or the clip is muffled, every time at the same point in the clip, there is a possibility that the 6116 RAM at U4 has failed.

'''Sound volume is extremely loud'''
Possible TDA1543 (U26) chip failure or counterfeit chip.

'''Loud hum'''
If there is a loud hum coming out of the speakers as soon as the game is turned on, make certain that the +12V is present.

'''Loud hum/burnt speakers/12V DC coming out of the speaker connector'''
If you have a machine with all speakers dead, check for voltage on the speaker wires. If the -12V wire from the driver board to the CPU board is disconnected, it can cause 12V DC to be sent down the speaker line, causing a loud hum and fairly quickly destroying any speakers connected!
 

'''Music Sounds Like Alvin and the Chipmunks'''
[[File:WhiteStarW6JumperLocation.jpg|left|thumb|300px|Schematic diagram showing the physical location of jumper W6 between the sound section 68B09E and the BMST2000, enabling the use of 8Mb EPROMs]] 
The original WhiteStar schematics mention jumper W6, which "must be installed for games that use 8Mb Sound EPROMs (U17 U21 U36 U37). For games which use 4Mb Sound EPROMs this jumper is not installed but 4Mb EPROMS will work on boards with W6 installed". This boils down to...install jumper W6. The manifestation of using 8Mb ROM images on a board with W6 not installed is sound that appears to be "Alvin and the Chipmunks"-like.

[[File:YT.png]] A YouTube video showing an incorrectly jumpered WhiteStar MPU with Harley Davidson ROMs can be found [https://youtu.be/7MXxngST5g4 here].

Note that the WhiteStar (modified) MPU board does not provide jumper W6, nor is it needed. The WhiteStar modified board works with both 4Mb and 8Mb sound ROMs, as if W6 was installed.
 

====Sound Section Jumper Settings====
JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket). An incorrectly jumpered or installed RAM chip can result in no sound at all.

'''Important:''' Under normal operation...
*JMP2 should be on the right pair of pins
*JMP3 should be on the top pair of pins, and
*JMP4 should be on the bottom pair of pins.

Placing the jumpers in any other position will cause sound to be missing. These jumpers are provided to update the sound operating system within the flash memory at U8.
 

====Loud Hum and/or Distortion at Low Sound Levels====
[[File:SternServiceModForLowSoundLevels.jpg|300px|thumb|left|Trim POTs connected across R106 and R110. This mod was offered by an aftermarket seller. Image courtesy of Jack Jarrett]]
[[File:WhiteStarResistorHack.jpg|300px|thumb|right|Trim POTs connected across R106 and R110 in a rather kludgy way...but it works. Image courtesy of PinSider Capt_Pinball]] 

Stern released [http://www.sternpinball.com/upload/downloads/sb133.pdf Service Bulletin 133], which discusses a fix for a loud hum and / or distortion when the master volume is set below level 4. The machines that are specifically effected are Monopoly and Austin Powers. However, it has been over 10 years since these games have been released, and boards get transplanted to other games over time. So, it is important to check the two resistors (R106 and R110) in the amplification section of the CPU / sound board to see if the correct values are installed, regardless of the game. The correct resistor values should be 33K ohms 1/4 watt for R110 (ORG-ORG-ORG-GOLD), and 10K ohms 1/4 watt for R106 (BRN-BLK-ORG-GOLD). Consult the service bulletin for more details, and the layout of the amp section. The R106 and R110 control the analog volume. When these resistors are broken (open) the analog volume goes to 100% and can't be controlled via the buttons (digital volume) on the coin door. The higher the resistor value the higher the volume.

Another method of accomplishing the same thing, without removing and replacing a resistor, is to add a resistor to the back of the board, across R106 and R110, creating the equivalent resistance as mentioned above. A 4.7K resistor seems to be a sweet spot.

Yet another method used is to clip a 10K trim pot across each resistor as shown in these images. The trim pot can be adjusted to a good compromise between hum and volume.
 

==== Low Background Sound Volume ====
[[File:WhiteStarBackgroundSoundVolume.jpg|300px|left|thumb|Background sound level setting on Roller Coaster Tycoon]] 
Some games, at least Viper Night Drivin' and Roller Coaster Tycoon, provide a means of adjusting the level of the background sound. The sound can be adjusted from level 1 (loudest) to level 15 (lowest).
 

====Adding a Second Backbox Speaker to some Sega Games ====
[[File:NewSpeakerAndSpeakerBlank.jpg|300px|left|thumb|Adding a second backbox speaker may improve the sound in games shipped with a single backbox speaker. Buy the speakers in pairs. This image shows the new speaker installed onto the left speaker bracket, and the right speaker position "blank" from a StarShip Troopers game. The "blank" must be modified so that the new speaker can be attached.]] 
A chap named Martin Riley submitted a nice article to the PinballNews explaining how to add a second backbox speaker to games like StarShip Troopers.

From the article... 
"Mid-life Sega games from Twister through to and including Viper Night Drivin' only had the left hand backbox speaker plus the cabinet speaker and only two of the 3 audio amps are populated on the CPU board.

Late Sega games from Lost in Space onwards have two backbox speakers but they are effectively mono as they are both connected to the left channel audio amp on the CPU board (the right channel amp being unpopulated)."

The complete article can be found at http://www.pinballnews.com/learn/speaker/index.html

The article lists all components required to add the 3rd speaker channel. Some (maybe all) two channel boards are not stuffed with C122, which is not listed in article parts list. You'll need one more 0.1µF axial ceramic capacitor for C122.

Adding a 3rd speaker to StarShip Troopers improved the sound quite a bit. The sound is richer and cleaner. The emphasis on some sounds is more pronounced and easier to hear. Edit: months later, I was testing a board in my StarShip Troopers that didn't have the 3rd amp. Forgetting that I had added the 3rd amp to my MPU, I initially thought something was wrong with the sound that the MPU under test was producing. It was merely the difference between a single and dual backbox speakers.

Mounting the additional speaker to the "blank plate" (as found in StarShip Troopers) required drilling the rivets that attach the speaker grill, and replacing them with low profile head screws. This is only necessary for Sega "Showcase" backbox games. For games like Independence Day, mounting the additional speaker should be trivial.

 

==== Is a Second Backbox Speaker Really Worth It? ====
While some have reported good results adding a third amp and second backbox speaker to these early Sega games, there are questions about the efficacy of such a solution. While better speakers themselves will improve the sound, the game-specific sound samples in the ROMs are mastered as mono sound clips. There are very few sounds in the game that are true stereo sound and these are usually simple sound effects which were used in multiple games. 

You can listen to and judge for yourself by running the Bridge front end and the M1 MAME music player. Bridge and links to the M1 player can be found [http://www.e2j.net/downloads.html here]. 

The mono mastering continued through the White Star II and SAM systems. As David Thiel, who has created music and sound for numerous Data East and Stern pinball machines, states on this [http://daudioguy.multiply.com/video/item/5/Family_Guy_Stern_Pinball_Music_and_Sound_Effects_by_David_Thiel?&show_interstitial=1&u=%2Fvideo%2Fitem page] of his website, he "composed, arranged, performed, mixed and mastered (all the music for Family Guy) for 24 kHz 16 bit Mono." 

===Flipper problems===
====Non-Functioning Flippers====
====Weak Flippers====
=====Progressively Weak Flippers=====

==Game Specific Problems and Fixes==
'''Lord Of The Rings''' 

If your Balrog stops registering hits, a little checking will sort it out. The mini microswitch with a roller arm used to register hits may need adjusting. Known past problems are a flaky or bad switch, and/or wiring. The Balrog moves in such a way that wires can break inside where you can't readily see them. It's easy to check the switch and wires with a meter. The wires push into an IDC connector nearby; be sure they are pushed in tight.

There isn't any adjustment for the micro switch, except for bending the blade with the mini-roller; try bending the blade outwards slightly. According to the manual, sw #28 stays normally closed and then a Balrog hit opens the switch. This is not the normal target arrangement. So using the Balrog test mode in diagnostics, the switch should stay solidly closed, and then only open when Balrog is tilted forward.

'''The Shire and Gimli VUK switches.''' 
These get hammered on LOTR and will eventually need replacing, There isn't any easy solution other than replacing the flaky switch. The tiny black screws on the Stern switches are 3/16". You will need a nut driver that size if you want to attempt replacement of the switches.

The Shire (and Gimli) VUK switch, are fork blade microswitches. Stern part number 180-5116-01. 
Spec on side of switch says Cherry .1A 125v E63. Try parts4pinballs.com or your favorite Stern parts supplier.

The Shire VUK. 
It's easiest to remove the entire Bottom Left VUK coil and bracket from under the PF (playfield) to change the fork switch. 
Take out the two largest bolts first, using a cross-head (phillips) screwdriver on the top and 11/32" nut runner (or socket) on the bottom. 
Remove the metal VUK arch from the top of the playfield. 
Remove the two lower wood screws (1/4" drive) leaving the one on the corner near the T-nut. 
Supporting the Coil Bracket, remove the last 1/4" screw. 
Unclip the connector from the coil and VUK. Remove coil and bracket assembly. 

Microswitch small screws are 3/16". As stated before, to remove the switch correctly you need a nut driver (or socket) that size.
You should be able to slide the heatshrink tubing all the way up the wires, solder on the new switch and then slide them back down in place. If not, use new heatshrink tubing. Assembly is above steps in reverse. Test in switch tests before replacing assembly and then by throwing a ball in the Shire in attract mode one the assembly has been correctly replaced.
 

'''Ripley's Believe it or Not! and The Simpsons Pinball Party''' 
Not certain what code versions apply with this. When the coin door is open, and the first ball drains, the game will not recognize that the ball has drained at all. Likewise, it will not kick the next ball over to the shooter lane. This is even with the solenoid voltage interlock switch pulled out. It is presumed that the memory lock switch has to be closed for the game to function properly.

This may apply to more games of this vintage other than just these two!
 

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.

*'''Striker Xtreme:'''
**Problem: '''Display is blacked out or only coming on for a few seconds before blanking out.'''
**Cause: Resistors R6 and/or R7 on the display power supply board have gone bad (open or increased in value).
**Solution: Replace resistors R6 AND R7 on the display power supply board. Both are 330k @ 1/2 watt
*'''Simpsons Pinball Party:'''
**Problem: '''When last ball drains, game still thinks its in play.''' Ball search or power cycle will eventually find it.
**Cause: Cracked solder joint on trough board.
**Solution: Pull both trough boards. A 1/4" wrench can be useful in getting the back board off. In this case, the obviously cracked solder connection was on the receiver board in front. But while the board is out, the optos were cleaned with Windex.
**This can be verified by waiting for the problem to show up, then go into switch test. Previously, switch #5 (leftmost) had been suspected and had been re-aligned, but that was probably not necessary.
*'''Starship Troopers, but applies to all:'''
**Problem: '''No display, no sound, upper amplifier went up in smoke.'''
**Cause: Connector CN4 on MPU / Sound board and CN1 of display power supply board were swapped. Both CN4 and CN1 are keyed the same. In haste, these connectors can be mixed up. Keep in mind that the speaker output is a very light gauge wire versus the heavier gauge for the display power supply input.
**Solution: This was not as bad as expected. After studying the schematics, only +20V (CN1 pin 6 - pin 4 is GND on both connections) can potentially backfeed through the sound circuitry. Amplifier U101 failing spectacularly possibly prevented additional damage. Amps U101 and U102 were replaced (U100 was not stuffed on this board). After replacing the amps, sound came back, but was very faint. Further investigation revealed 3 100Kohm resistors had failed, R21, R22, and R24. Also, U26, the TDA1543 DAC, had also failed.
*'''Goldeneye, but applies to all:'''
**Problem: '''Blanking signal OK but driver board blanking LED keeps blinking.'''
**Cause: Ribbon cable from MPU to driver board faulty.
**Solution: Replace ribbon cable.
*'''Goldeneye, probably Twister:'''
**Problem: '''Magnets don't work, MAG2 LED on magnet board keeps blinking in test mode.'''
**Cause: Bad connection from magnet board to magnet between flippers.
**Solution: Fix connection.

Sega/Stern White Star Repair

2023-03-23T09:39:25Z

Jimpal: Reverted edits by ForceFlow (talk) to last revision by Chibler

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

==Introduction==

 

==Games==
===Sega===
*Apollo 13
*Goldeneye
*Twister
*Independence Day
*[[Space Jam]]
*Star Wars Trilogy
*The Lost World Jurassic Park
*The X Files
*[[Starship Troopers]]
*Viper Night Driving
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park

===Stern===
*Striker Xtreme
*[[Sharkey's Shootout]]
*High Roller Casino
*Austin Powers
*[[Monopoly]]
*NFL
*Playboy
*Roller Coaster Tycoon
*[[The Simpsons Pinball Party]]
*Terminator 3: Rise Of The Machines
*The Lord Of The Rings
*Ripley's Believe It Or Not
*Elvis
*Grand Prix
*The Sopranos
*NASCAR

==Recommended Documentation==
===Manuals===
The owner's game manual is a handy resource to have for general game operation, game settings & diagnostics, switch & lamp matrices, fuse lists, circuit boards and parts, playfield assemblies, some basic schematics, and wiring diagrams. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended [http://pinwiki.com/wiki/index.php?title=Pinball_Parts_Suppliers pinball parts suppliers]. Some Stern White Star Game manuals are available in PDF form on the Stern Pinball website. They are on the game specific pages of the Stern website. An index of games can be found in the right margin [https://sternpinball.com/support/game-manuals/ here]. 

As of April 2014, the Stern Pinball website no longer archives theory of operation and board schematics in PDF format. 

Be aware that although rare, some factory documentation contains errors in schematics, wiring, switch/lamp matrices, and solenoid assignments.

===Schematics===
Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids.

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===Service Bulletins===
Service bulletins detailed any problems or issues with games that were discovered after they were released.

Service bulletins for all Stern games can be found [https://sternpinball.com/support/service-bulletins/ here.]

As of 2014, service bulletins for Data East and Sega games are no longer directly available on the Stern Pinball website, but [https://web.archive.org/web/20130520091730/http://sternpinball.com/ServiceBulletins.shtml can be found on an older archived version of the website].

{| class="wikitable sortable"
|-
!Service Bulletin
!Date
!Game(s)
!Summary
!Notes

|-
|166
|2006, September 20
|Grand Prix & NASCAR
|Trough Up-Kicker Failure
|
|-
|162
|2006, July 11
|The Simpsons Kooky Carnival, MONOPOLY and TITANIC Redemption Games
|Electronic Coin Mech Coin Return Lever Sticks
|
|-
|161
|2005, March 21
|NASCAR / Grand Prix
|NASCAR / Grand Prix Enter/Exit Scoop Modification & 1-Way Gate Bracket Update Kit (502-5048-86); ONLY FOR NASCAR/GRAND PRIX GAMES with SERIAL NUMBERS LOWER THAN <195160 (NASCAR) and LOWER THAN < 19620 (GRAND PRIX) Production Prior December 2006
|
|-
|160
|2005, November 8
|NASCAR
|NASCAR SOFTWARE UPDATE (CPU/GAME ROM U210); ONLY FOR NASCAR GAMES with CPU Version 3.30 or LOWER
|
|-
|159
|2005, August 31
|NASCAR
|NASCAR T-Nut Cover & Target Foam Kit (SPI PN: 502-5042-00), EARLY PRODUCTION GAMES ONLY
|
|-
|158
|2005, August 26
|NASCAR
Early Production Games ONLY
|NASCAR 2-Pin OPTO Ground Connector in Backbox, EARLY PRODUCTION GAMES ONLY
|
|-
|157
|2005, June 20
|Terminator 3, The Lord of the Rings, Ripley's Believe It or Not!, ELVIS, Harley-Davidson 3rd Edition and The Sopranos
|New Version 8 of the Sound Operating System (O/S)* for the White Star CPU/Sound II Board bootFLASH file for EPROM; This new version O/S 8 is compatible with all previous versions of CPU/Snd II ROM’s.

|
|-
|156
|2005, May 5
|The Sopranos
|Cabinet Flipper Switches - Contact Pitting
|
|-
|155
|2005, April 15
|The Sopranos and future Pinball Games
|FYI: Lockdown Assembly & Front Molding Change during the production of The Sopranos Pinball and future Pinball Game Titles
|
|-
|154
|2005, February 20
|Lord of the Rings
|Lord of the Rings Post Upgrade Kit (502-5034-00) ONLY games prior to Feb. 2005 (production of LOTR games after Feb. 2005 have post in place).
|
|-
|Nr. 153
|2004, December 15
|Ripley's Believe It or Not!
|Ripley's Believe It or Not! Software Update
|
|-
|Nr. 152
|2004, August 27
|general
|FYI: STERN Pinball Flipper Evolution
|
|-
|Nr. 151
|2004, July 20
|Lord of the Rings
|Potential flipper & ring magnet fuse fatigue
|
|-
|Nr. 150
|2004, June 21
|general
|Back to Basics: Insertion/Replacement of EPROMS in SPI Games
|
|-
|Nr. 149
|2004, May 18
|Ripley's Believe It or Not!
|Potential Ball Trap by the Upper Left Pop Bumper (ask your Distributor for SPI Kit Nr. 502-5025-81)
|
|-
|Nr. 148
|2004, April 29
|The Lord of the Rings
|Balrog LED Module Installation, SPI Kit Nr.:502-5022-00
|
|-
|Nr. 147
|2004, January 19
|The Lord of the Rings
|Diverter Gate Adjustment Procedure
|
|-
|Nr. 146
|2003, December 18
|The Lord of the Rings
|FYI: The Lord of the Rings Tower Eject Learning Mode
|
|-
|Nr. 145
|2003, December 9
|Terminator 3 Rise of the Machines
|T3 Auto Launch Diode Harness Installation (SPI Part Number 502-5017-00)
|
|-
|Nr. 144
|2003, December 9
|The Lord of the Rings
|The Lord of the Rings Spanish Display & Speech Available
|
|-
|Nr. 143
|2003, October 22
|Terminator 3 Rise of the Machines
|T3 Software Update/Match Feature
|
|-
|Nr. 142
|2003, August 22
|Terminator 3 Rise of the Machines
|T3 Auto Launch Wire(s) or Coil Lug(s) Break Off
|
|-
|Nr. 141
|2003, August 13
|Terminator 3 Rise of the Machines
|Shooter Lane Switch Actuator Adjustment
|
|-
|Nr. 140
|2003, July 24
|Terminator 3 Rise of the Machines
|T3 Software Update v2.04 or Higher Eliminates POTENTIAL Reset Problem
|
|-
|Nr. 139
|2003, May 16
|Monopoly
|F21 (50vdc) Fuse Blows Intermittently, System Checks OK on
|
|-
|Nr. 138
|2003, March 21
|The Simpsons Pinball Party
|The display flashes a Tech-Alert upon Power-Up
|
|-
|Nr. 137
|2002, July 22
|Austin Powers
|CPU GAME ROM v3.01 Bug
|
|-
|Nr. 136a
|2002, June 21
|Playboy
|U7 Sound ROM Update DOES NOT RESOLVE the problem
|
|-
|Nr. 136
|2002, May 2
|Playboy
|U7 Sound ROM Change
|
|-
|Nr. 135
|2002, May 1
|Monopoly
|Optional Monopoly Butyrate Fix Kit (SPI: 502-5012-00)
|
|-
|Nr. 134
|2002, April 11
|general
|Difficulty in Playfield Glass Removal
|
|-
|Nr. 133
|2002, April 1
|Monopoly / Austin Powers
|CPU/Soundboard Modification Low Volume Setting Hum
|
|-
|Nr. 132
|2002, March 4
|Playboy
|Back To Basics: Using Your Adjustable Outlane Posts
|
|-
|Nr. 131
|2002, Jan. 23
|Monopoly
|Electric Company Sign / Backbox J2 Harness Re-dress
|
|-
|Nr. 130
|2001, Dec. 10
|Monopoly
|Tips & Tricks - The Water Works Rotating Flipper
|
|-
|Nr. 129
|2001, Oct. 22
|Monopoly
|Playfield Mylar, SPI Part Number: 820-5094-00
|
|-
|Nr. 128
|2001, Sep. 19
|Austin Powers
|Code Update v3.00 CPU/Display: Addition of Adj.60: Washington D.C. Enabled (Factory Defaults is "Off")
|
|-
|Nr. 127
|2001, Sep. 19
|Striker Xtreme / NFL
|Plastic Stadium Flashlamp Removal
|
|-
|Nr. 126
|2001, Sep. 19
|general
|The Bubble Level is Back!
|
|-
|Nr. 125
|2001, April 19
|general
|Quick Tip for Display Troubleshooting: U201 White Starboard System
|
|-
|Nr. 124
|2001, March 16
|Sharkey's Shootout/ High Roller Casino
|Software Update: Replay Bug Fix
|
|-
|Nr. 123
|2001, March 6
|High Roller Casino
|Ball Trap Fix @ Bottom Bumper
|
|-
|Nr. 122
|2001, Feb. 22
|High Roller Casino
|Roulette Wheel (Top and Bottom) Assembly
|
|-
|Nr. 121
|2001, Feb. 5
|Harley-Davidson
|Plastic (Butyrate) -15 Support Plate Kit(SPI Nr. 502-5003-67)
|
|-
|Nr. 120
|2000, Dec. 29
|Sharkey's Shootout
|Mystery Ball Magnet Fuse Fatique: CPU Software Code 2.04 Update
|
|-
|Nr. 119
|2000, Nov. 8
|general
|Pinball Preventative Maintenance Inspection
|
|-
|Nr. 118
|2000, August 21
|Striker Xtreme / Sharkey's Shootout
|Drop Target Replacement Procedure
|
|-
|Nr. 117
|2000, June 13
|general
|Please Join our Service Bulletin eMail Distribution
|
|-
|Nr. 116
|2000, June 12
|Titanic
|Titanic Redemption Game Potential Revenue Loss
|
|-
|Nr. 115
|2000, May 3
|Stiker Xtreme
|Stiker Xtreme Earnings
|
|-
|Nr. 114
|2000, Feb. 11
|Harley-Davidson
|Operator Alert #19 - Motor Relay
|
|-
|Nr. 113
|1999, Dec. 10
|Harley-Davidson
|HD Ball Guide... & Butyrate - 16... Kit
|
|-
|Nr. 112
|1999, June 7
|A13 >> Current
|CPU U218 & I/O U210 Pin-3 Removal
|
|-
|Nr. 111
|1999, Feb. 18
|South Park
|8MG E-PROM's for Expanded Speech & Sound Capabilities
|
|-
|Nr. 110
|1998, Nov. 24
|Space Jam >> Current
|Modular Stand-Up Targets: a new way to order
|
|-
|Nr. 109
|1998, Sep. 30
|Godzilla
|...Manual Addendum: Flipper Coils
|
|-
|Nr. 108
|1998, August 18
|Prior<<Batman Forever>> current
|"Sega"...& "Data East" ... Flipper Rebuild Kits
|
|-
|Nr. 107
|1998, August 13
|All Games (General)
|Fax Response Survey: How would you like your...
|
|-
|Nr. 106
|1998, June 2
|Multiple Games
|Large Dot Display Optional Enhancement Cable
|
|-
|Nr. 105
|1997, Nov. 21
|The X-Files
|...-Playfield Update Kit (500-6281-00)
|
|-
|Nr. 104
|1997, Sep. 25
|Multiple Games
|Future Parts & Service Pinball ...(Questionaire)
|
|-
|Nr. 103
|1997, July 14
|Playboy thru Rocky & Bullwinkle & Friends
|Solid State Flipper Bd. ( Non E.O.S.) conversion
|
|-
|Nr. 102
|1997, June 20
|The Starwars Trilogy-Special Edition
|FYI: What's New ("Y" Actuator Heavy Duty Sw.)
|
|-
|Nr. 101
|1997, June 10
|The Lost World: Jurassic Park
|Important Unpacking Information
|
|-
|Nr. 100
|1997, May 19
|The Starwars Trilogy-Special Edition
|Software CPU/Display Final Code Version
|
|-
|Nr. 99
|1997, May 13
|Multiple Games
|FYI: Correct P/F Glass Dimensions ...Wide Body
|
|-
|Nr. 98
|1997, April 8
|The Starwars Trilogy-Special Edition
|Addition of Reset Align. Bracket Kit
|
|-
|Nr. 97
|1997, April 8
|The Starwars Trilogy-Special Edition
|X-Wing Motor Bushing
|
|-
|Nr. 96A
|1997, May 12
|Space Jam >> Current
|Dot Matrix Display Bd. 4X Spacer/2X Bracket
|
|-
|Nr. 95A
|1997, April 11
|The Starwars Trilogy-Special Edition
|...Reed Sw. Replacement Kit...&Procedure
|
|-
|Nr. 94
|1997, March 3
|Lethal Weapon 3 >>Current
|Flipper Alignment Spots
|
|-
|Nr. 93
|1997, Jan. 27
|Space Jam
|FYI: ...problem in... I/O Power Driver Boards
|
|-
|Nr. 92
|1996, Dec. 5
|Apollo 13 >> Current
|FYI: MOSFETs in the White Star Bd. System
|
|-
|Nr. 91
|1996, Nov. 27
|Twister
|Magnet Processor Bd. & Disc Motor Updates
|
|-
|Nr. 90
|1996, Nov. 20
|Space Jam >> Current
|FYI: Sega Showcase Backbox
|
|-
|Nr. 89
|1996, Nov. 19
|Apollo 13 >> Current
|FYI: Switches
|
|-
|Nr. 88
|1996, Oct. 14
|All Games (General)
|Excerpt From Customer Fax
|
|-
|Nr. 86
|1996, Sep. 3
|Independence Day
|Potential Ball Trap in the Plastic Under-Trough
|
|-
|Nr. 85
|1996, May 15
|Twister >> Current
|New 2-Flipper Theory of Operation and Schematic
|
|-
|Nr. 84
|1996, March 5
|Golden Eye
|Fuse/Power Updates
|
|-
|Nr. 82
|1996, Jan. 23
|Apollo 13 >> Current
|The New "White P Star Board System"
|
|-
|Nr. 81
|1996, Jan. 9
|Apollo 13
|System Update
|
|-
|Nr. 80
|1995, Dec. 21
|Apollo 13
|Theory of Operation: P/F Mag. Intrface & 7-Seg.
|
|-
|Nr. 79
|1995, Dec. 18
|Apollo 13
|5 Amp to 3 Amp Slo-Blo Fuse Change
|
|-
|Nr. 77
|1995, August 24
|Current Games
|"What is this pinball machine trying to tell me?"
|
|-
|Nr. 75
|1995, August 22
|All Games
|CPU Board - Blanking Circuit Theory of Operation
|
|-
|Nr. 72
|1995, Feb. 17
|Mary Shelley's Frankenstein
|Creature: A Technical Overview
|
|-
|Nr. 70
|1995, Feb. 14
|Mary Shelley's Frankenstein
|Software Change Notice
|
|-
|Nr. 68
|1995, Jan. 27
|Frankenstein (+ games hereafter)
|New Service Feature: Bi-Directional Aud/Adj/Diag.

|}

==Technical Info==
===Schematics===
While these schematics were removed from Stern's web site quite some time ago, they can still be found using "the Wayback Machine". 

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===The White Star Board Set===
[[File:Stern WS Boardset.JPG|left|thumb|300px|Typical Early Stern White Star Boardset (Monopoly)]] 
The White Star System board set consists of three boards mounted to the the back box, but four boards total. The CPU / Sound board, I/O Power Driver board and the Display Power supply. Additionally, there is a dot matrix display controller mounted to the backside of the dot matrix display. On some games, the dot matrix display controller is mounted to the backbox instead. 

The first two White Star games, Apollo 13 and Goldeneye, both used an additional solid state flipper control board. Starting with Twister, the solid state flipper board was abandoned, and flipper control became an additional duty for the I/O power driver board. 

In addition to pinball machines, the White Star board set was used in several redemption games made by Sega and Stern. Some of the games are Wack-A-Doodle-Doo, Sega Sports, Titanic, and Monopoly redemption.
 
====CPU / Sound Board====
<center>
<gallery widths=500px heights=300px perrow=2 caption="Generations of the Sega/Stern White Star MPU">
File:A13MPU.jpg|<center>Sega White Star CPU/Sound Board 520-5136-00 Rev. D with 3 channel audio output (Apollo 13)</center>
File:Sega WS CPU Sound 520-5136-16 Rev. D.JPG|<center>Sega White Star CPU/Sound Board 520-5136-16 Rev. D (Wack-A-Doodle-Doo)</center>
File:Stern WS CPU sound.JPG|<center>Stern White Star CPU/Sound Board 520-5136-16 Rev. E (Monopoly)</center>
File:SternWhiteStarAtmelProcessor.jpg|<center>Stern White Star CPU/Sound Board II 520-5300-00 (LOTR and forward). U201, U213, and U413 are socketed on this board as a result of alkaline damage abatement.</center>
</gallery>
</center>
 

There are two versions of the White Star CPU/Sound board.

The board used in Sega machines starting with Apollo 13 (A13) and Stern machines up to Terminator 3 (T3) are the standard version as shown above with the BSMT2000. There were different revisions of this board, which included slight component changes and modifications. However, there were some distinct changes to the board from revision D to revision E. The Q9 transistor located just below U212 (RAM memory) was removed, and a two pin jumper (JP1) was added. Additional circuitry allowed for increased RAM memory from 8K to 32K. Jumper JP1 is used to select between use of a 6264 or a 62256 RAM. '''Note:''' While a 62256 RAM can be used in any game MPU, Sharkey's Shootout specifically requires a 62256 RAM. 

Stern machines starting from Lord of the Rings (LOTR) used a different version of the White Star CPU/Sound board called White Star CPU/Sound Board II or more commonly WhiteStar (modified), part #520-5300-00. Stern had this in-between version made because the BSMT2000 audio chip wasn't available anymore and having it reproduced was too expensive. The White Star II therefore uses an BSMT2000 emulation circuit consisting of an Atmel AT91R40008 microcontroller and an Atmel AT49BV1614-11TC 16Mbit flash memory. Later boards use a AT49BV162AT-70TI flash memory chip. Both flash chips are obsolete now. The boards are known for sudden sound failures sometimes because of a bad flash chip and it is advisable to buy a spare. If the amplifier section is good the most common cause for sound failures is the U414 Xilinx CPLD. This chip is a programmed by Stern via the JTAG connector. While some repairmen have the skill to replace the chip, only Stern can "flash" the code into the chip.

Note: Stern states that the Atmel version board is backwards compatible with the standard (BSMT2000) version, so it can be used in *some* White Star based games (in most cases, Stern branded White Star games only - including South Park and Harley Davidson) prior to LOTR as well. However, the only games which the board can be installed in must use 8mb EPROMs for the sound section versus the 4mb EPROMs more commonly found on Sega White Star based games. If the CPU/Sound board II is used in early games, Starship Troopers for instance, some sounds may not render correctly. 

Additionally...The original BMST2000 based board is not forward compatible with later games like LOTR, etc. 

The BSMT2000 based White Star sound system is nearly identical to the sound circuitry found on Data East/Sega soundboards 5020-5050-0x, 5020-5077-00 and 5020-5126-02.

The board uses TIBPAL16L8 PAL ICs. These are programmable logic chips Stern used to condense a great deal of TTL logic into a single chip. Each PAL is marked with a colored dot for identification and configuration management. U213 is one of these PALs that is within the battery corrosion area. It is readily available, already programmed under part number 965-6504-00 (blue dot), the only exceptions to the blue dot being Sharkey's Shootout which uses part number 965-5023-00 (gold dot) and Lord of the Rings LE with a shaker motor installed which uses a different part number (the standard LOTR without a shaker motor uses the standard 965-6504-00 but the software version supporting the shaker motor will only run on the alternative U213).

There are two more PAL chips on the board at U19 (yellow dot, 965-0136-00) and U20 (white dot, 965-0137-00). These aren't needed very often for repair of the sound section but they do fail now and then.
 
Sega first used standard TIBPAL chips and later switched to reprogrammable PALCE devices. The latest boards from Stern use GAL chips. In the old PAL chips, fuses are burned so they do not have a data retention period. For the programmable logic chips the data retention period is generally specified at 20 years or more at operating temperature. The first White Star boards are from 1995 Beginning in 2015, all with reprogrammable chips begin to exceed the data retention period and although big problems are not to be expected, it wouldn't be surprising if these parts begin to fail.

The programmable logic in the board design makes it harder to repair the boards because of the grey area it causes in the schematics as there aren't any logic diagrams of these available. In short; you don't know what they do so you don't know what the output should be.

'''"Blink Codes"''' do not exist for the 68B09E or the Atmel based MPU. With one exception (Atmel based board) anything blinking is a side-effect of improper board operation. The blinking may help you diagnose the actual board problem, but blinking LEDs are not driven with intent by the processors. i.e. There are no "Bally -17-like Blink Codes".

The single exception to this is LED1 on the Atmel based MPU. LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin # 157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another).

There are two [http://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] (Joint Test Action Group) connectors available on the Atmel based board. One connects to the Xilinx [http://en.wikipedia.org/wiki/Complex_programmable_logic_device CPLD] (Complex Programmable Logic Device). The other connects to the Atmel R40008 processor. The JTAG interfaces to this board and their use have not been documented publicly.

As of April 2014, schematics for the 520-5136-16 board are no longer available from Stern's website. 
As of April 2014, schematics for the 520-5300-00 board are no longer available from Stern's website. 

=====BSMT2000 DSP Info=====
[[File:BSMT2000.jpg||left||thumb||300px||BSMT2000 audio chip]] 
Like the earlier Data East boards, the first White Star generation uses a TI DSP for sound processing. The chip is just a relabeled mask programmed stock Texas Instruments TMS320C15NL-25 DSP. The 8K mask programmed ROM is custom programmed during manufacturing and can not be read out, reprogrammed, or altered in any way. Only the ones labeled BSMT2000 will work in a pinball. For prototyping, the TMS320P15NL-25 and TMS320E15NL-25 were available which included a more-or-less standard 27C64 EPROM. The pictures on the left shows a BSMT2000 and a TMS320P15NL-25 out of a Sega board. The hand labeled chips are rare but if you have one in your pin, you can read it out. The security fuse was not set on the device in the picture. If you build an adapter using a 27C64 and some logic which puts the DSP in microprocessor mode and does the address decoding it might even be possible to use the C10 and C15 devices because the internal ROM is not used in this mode.
 

=====WhiteStar Switch Circuitry=====
Both versions of rhe WhiteStar CPU/Sound board employ an 8 by 8 (8 switch columns, 8 switch rows) switch matrix. In addition to the typical switch matrix, an extra column of switches, which are dedicated to specific functions like coin door switches, appear on all WhiteStar games.

Flipper cabinet and end of stroke (EOS) switches are part of the dedicated switch set on games after Goldeneye.

A combination of microswitches, opto switches, leaf switches (on most drop target assemblies), and reed switches are used.
 

====Power Driver Board====
The Power Driver board supplies fused power, GI power and fusing, lamp matrix circuitry as well as coil and flash lamp drivers. A watchdog circuit also must communicate with the MPU periodically to allow the MPU to boot and operate properly. 

As of April 2014, schematics for the 520-5137-01 board are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-64 board (Sharkey's Shootout Tournament Edition only) are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-01 board (100 ohm resistors added on J2 aux. port lines) are no longer available from Stern's website. 

High current coils (50vdc) 1-8 (group 1) and 9-16 (group 2). Q15 and Q16 typically drive the left and right flippers respectively. 
Low current coils (20vdc) 17-24 (group 1) and 25-32 (group 2). 
 

Please be advised that four revisions of these board exist. The letter after the number indicates the revision. See below. All existing Stern schematics are wrong.

=====Revision D: First revision=====

=====Revision E: Second revision=====
[[File:Stern WS Driver.JPG|left|thumb|300px|Stern White Star I/O Power Driver Board Rev E]] 

*Not fully stuffed. Parts for flipper boards connector J4 and J5 are not stuffed.
 

=====Revision F: Third revision=====
[[File:IO driver rev F.jpg|left|thumb|300px|Rev F of the Sega/Stern IO Power Driver Board.]] 

*C25 changed from 470µF 100V to a 330µF 160V Snap-In capacitor
*U210 pin 3 is cut to allow for a 10% input voltage tolerance before resetting, aka "low line voltage". This was documented in Stern service bulletin #112 which can be found [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf here]. However, a better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 5% (to about 4.75VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

*J2 modified and 100 Ohm resistors R258 to R260, R273 -R277 added (see schematics)

 

=====Revision G: Fourth revision (not documented by Stern)=====
[[File:IO driver rev G.jpg|right|thumb|300px|Rev G of the Sega/Stern IO Power Driver Board.]] 
The most obvious change to the Rev G driver board is the addition of eight 100 ohm resistors under the J2 aux out connector (R258-260, R273-277). This board is backwards compatible with all machines that use the I/O Power Driver board. It is possible to add these resistors to the back of J2 for I/O board Rev F, jumping from the connector pins to the capacitors below the J2 connector to make the board compatible with those games that use the J2 connector.

This is the only version that will work with the TOPS system.

Parts deleted:

*Original R256, D228, R255 and C236 above U210 were removed

Modification 1:

J3 Pin 8 is no longer a key pin. The installed pin is connected to R255/R256 and to C236. The other side of these parts is connected to:

*R255 to D217 banded side like R245 to R251
*C236 to GND like C229 to C235
*R256 to U203 Pin 11 (LST lamp status)

The LST trace to D221 to D227 is missing. The diodes are still connected to the status output line of the VN02 solid state relays. It seems that this status is not queried by the game software or can just be ignored.

Modification 2:

*U210 Pin 3 is connected to R257.
*R257 is connected to GND but not stuffed!

Modification 2 is not necessary. A better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 10% (to about 4.50VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

New parts:
*R255 1K
*R256 39K
*R257 not stuffed
*C235 470pfd

===== Sharkey's Shootout Specific Driver Board =====
[[File:SharkeysShootoutWhiteStarMod.jpg|left|thumb|300px|Cuts and jumpers applied to the Sharkey's Shootout specific I/O Driver Board.]] 
The now defunct Stern web site containing schematics listed a few differences in the I/O Driver Board for Sharkey's Shootout. Those differences are identified in the image at left.

One other change to the board is shown on page 5 of the Sharkey's Shootout unique I/O Driver Board. Fuse F20 is changed from a 3ASB to a 4ASB.
 

===== RottenDog WhiteStar 5V Voltage Regulator =====
[[File:RottenDogWhiteStarVoltageRegulator.jpg|left|thumb|300px|RottenDog LM317 Replacement.]] 
The RottenDog aftermarket power/driver board uses the voltage regulator shown at left, primarily because the older LM317 voltage regulator has gone obsolete.
 

===== Lamp Matrix =====
The WhiteStar system is somewhat similar to previous lamp matrices designed by Data East, Sega and Williams. The main difference is instead of 8 lamp columns and 8 lamp rows (the typical 8 by 8 matrix), two additional lamp rows are used enlarging the matrix to 8 by 10.

===== TOPS Tournament System Driver Board Compatibility =====

Only the latest revision G is compatible with the Stern tournament system (TOPS). With earlier revisions while everything including the tournament sign seem to work ok a tournament can not be started. Pressing the tournament button will result in a 'Tournament Game Paused' message displayed on the DMD. The tournament button itself will also not light up during normal operation. The J3 Aux In connector has an additional pin instead of the key pin on these boards. Because of this the LST line to the lamp drivers goes nowhere on this revision.
 

====Display Controller Board====
[[File:Sega 520-5055-01 DMD Control Board.JPG|thumb|left|300px|Sega White Star Display Controller Board]]
[[File:AnnotatedDMDController.png|thumb|right|300px|Sega White Star Display Controller Board Layout with Ground Connections Shown]] 
The Schematics for this board can be found [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf here]. 

The display controller board doesn't contain circuitry to provide the on board 68B09E with a "reset" pulse. The reset signal is provided from the games MPU via a pin at the ribbon cable connection (J1 pin 20). The surface mount version of the board has provisions to provide a reset signal at U10, but the necessary components are not stuffed.
 

[[File:Stern WS DMD Controller.JPG|thumb|left|300px|Stern White Star Display Controller Board, surface mount version.]] 
As of April 2014, schematics for the 237-0255-00 DMD controller board (primarily surface mount components) are no longer available from Stern's website. 
 

[[File:SurfaceMountFailedSolderJoints.jpg|thumb|left|300px|A fractured solder joint (circled) on this board prevented the "power on" LED from ever lighting.]] 
The surface mount version of this board sometimes has dubious solder connections at some of the surface mount resistors and capacitors. The picture at left shows a fractured solder joint on the resistor in series with the "power on" LED. The LED would never light. Another fractured solder joint on the same board prevented the reset pulse from the MPU board from ever reaching the on board 68B09E.
 

====Display Power Supply====
[[File:Stern WS DMD PSU.JPG|left|thumb|300px|Stern 520-5138-00 Display Power Supply]] 

This WhiteStar game system high voltage power supply (for displays) is an evolution from the larger Data East power supply. The high voltage section of this board is nearly identical to the high voltage section of Data East power supplies 520-5047-01 and 520-5047-02. Of course, those earlier Data East power supply boards regulate and supply more than display high voltages (i.e. 5VDC). As such, the WhiteStar board could be made more compact while using almost identical parts.
 

====128 x 32 Dot Matrix Display====
All Sega and Stern White Star games make use of a 128 x 32 "standard" dot matrix display.
 

====White Star Manufacturing Quality====
[[File:WhiteStarFactoryUpdate.jpg|300px|left|thumb|Factory updates to the Sega/Stern White Star MPU.]]
[[File:WhiteStarMPUSolderSideFactoryMod.jpg|300px|right|thumb|Ceramic cap, 10 ohm 1/4 watt resistor, and a trace cut.]] 

Generally, White Star boards are manufactured quite well. The traces are very fine, making alkaline damage repair difficult. But, those batteries shouldn't be on the board, should they? The Atmel based MPU board uses a multi-layer PCB, which increases the need for clean component removal and replacement.

Pictured at left, are two factory updates to the original Sega/Stern White Star MPU (BMST2000 version). These are normal, and not "hacks".

As can be seen in the picture at right, a ceramic 100pF cap and a 10 ohm 1/4 watt resistor have been added and a trace has been severed. This modification results in the 10 ohm resistor and the cap being placed between BMST2000 "CLKOUT" signal at pin 6 and ground at pin 10.

An additional 100pF cap is placed between pin 5 "E" and 6 "!E" of U1.
 

[[File:WhiteStarU203CutAndDiode.jpg|300px|left|thumb|Another factory update to the Sega/Stern White Star MPU.]] 
Another factory update to the left of U206 involves two cuts, and the addition of a diode between D3 and R430. Again, this is not a "hack".
 

[[File:WhiteStarPCBSolderMask.jpg|300px|left|thumb|Small traces lead to some components on White Star boards, enabling better manufacturing quality.]] 
By the time White Star boards were being manufactured, improved methods of controlling solder temperature and junction temperature at the through-holes was much better understood. In the picture at left, the "spider" connections at some through-holes, allow less heat to be used to create quality solder joints.
 

===The Wire Coloring Code===
White Star games do not use color coding system. Instead, the wire color was marked accordingly in the associated documentation, (ie. a green wire with a brown trace is referred to as GRN-BRN, orange with violet is ORG-VIO, white is just WHT, etc.).
 

===Trough Opto Boards===
++++ Need pics of the single opto transmitter and receiver boards ++++++ 
[[File:Stern WS Trough Opto Transmitter.JPG|left|thumb|300px|Stern White Star Trough Opto Transmitter (Later Games)]]
[[File:Stern WS Trough Opto Receiver.JPG|left|thumb|300px|Stern White Star Trough Opto Receiver (Later Games)]] 
All White Star Games use trough opto boards at the location of the trough VUK which feeds the ball to the shooter lane. Earlier White Star games (Apollo 13 to Viper Night Drivin') use only a single opto above the VUK plunger. Later White Star games (Lost in Space to NASCAR / Grand Prix) use a two opto system. The lower opto serves a dual purpose. It is the opto just above the VUK plunger like earlier games, but is also designated as trough switch #4. The upper opto is designated as the "stacking opto". Its purpose is to identify when a ball inadvertently gets "stacked" above a ball located at the VUK plunger. 

To briefly summarize the operation of White Star VUK opto boards, if an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch. The components used on the opto receiver board are designed to do as such. 

The transmitter side is simply an ultra-red LED with a current limiting resistor. The receiving opto is the same style ultra-red LED, and is able to detect the light wavelength emitted from the transmitting LED. By using discrete components on the receiving side, the appropriate signal is sent to the CPU via the switch matrix return (row). When LEDs are paired together in this type of fashion, the receiving LED emits a very small amount of voltage, when the proper light wavelength is present. By employing such a design, failure on the receiver opto side is more common. 

This particular system is contrary to how Bally / Williams WPC CPUs handle opto pairs. Equally, WPC games employ infrared (IR) opto switch pairs. If interested in learning the theory of operations for the White Star opto trough upkicker boards, please consult the manual. Sega / Stern have included some excellent, detailed, technical documentation within their manuals. 

As of April 2014, schematics and troubleshooting info for the trough upkicker dual opto boards are no longer available from Stern's website.

Once significant source of trouble with these trough boards is fractured header solder joints. 

===Magnet Processor Board===
[[File:Sega mag driver board.jpg|300px|thumb|left|Sega 520-5143-00 Magnet Processor Board]] 
Only two Sega games used this style of magnet processor board - Twister and Goldeneye. When U1 for Twister is installed in the board, the board's part number is 520-5143-01. The part number for the board when U1 is written for Goldeneye is 520-5143-02. Difference between the board used on each game is the different custom PIC / GAL chip used at position U1 and the Goldeneye board has R10, R11, R12, R13, D11 and D12 stuffed. This is not always the case with boards for Twister.
 

===Flippers===
[[File:Stern Flipper Assy.JPG|left|thumb|300px|Typical White Star Left Flipper Assembly (Monopoly)]] 
All Sega / Stern White Star flipper assemblies are solid state controlled. Apollo 13 and Goldeneye are the only two White Star games which use a separate solid state flipper control board located in the game's lower cabinet. Starting with Twister, the flipper board was abandoned, and circuitry for the flippers was solely controlled by the FETs on the power driver board. 

Please note that the adjacent pic of the White Star flipper assembly has a Williams flipper link / plunger installed.

The drive circuit for White Star games is different than traditional flippers. The flipper coil is single-wound. There is no "hold" winding, just a single "kick" winding. Because the flipper will get hot if the kick winding runs continuously, after the initial upstroke, the computer continuously cycles the coil on so that it stays up. According to the manual, the flipper is pulsed about 1/12 of the time.

The flipper coil must have a snubbing diode.

A normally closed EOS switch is present. The purpose of the EOS switch is to detect when a fast-moving ball has forced the flipper down ("foldback"). Unlike a traditional or Fliptronic mechanism, the EOS switch is not used to detect end of stroke. That is, the EOS switch closing does not cause a switch from "kick" to "hold". If the flipper is supposed to be up, and the EOS switch opens, the game will re-energize the flipper coil. This helps with some features, particularly "laser" kickers that fire the ball into the flippers. The EOS switch should be present for improved play, but if it's broken, the flipper will work for the most part. However, in some instances, a flipper with a broken or missing EOS switch may be noticeably weaker. If a flipper seems weak or lethargic, the flipper mechanisms have been rebuilt, and the EOS switch is broken, try replacement of the EOS switch first before considering other options.
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
Solid state pinball machines typically have a built in system for audits and adjustments. All White Star based machines use a system called "Portals". The Portals interface is a carry over from the last two Sega games (Baywatch and Batman Forever) which used the original Data East board set.

====Portals (Coin Door Test Buttons)====
[[File:Stern white star coin door inside.JPG|300px|thumb|left|The Portals control panel used on most White Star games (Monopoly)]] 
The Portals system has a very user friendly, simple navigation system. Unlike previous Data East / Sega games, having to scroll through all of the audits and adjustments is a thing of the past. Diagnostic testing (including game specific assembly tests), audits, and adjustments can all be quickly accessed via the initial display menu graphical interface. The 3-button control panel (in most cases, except some earlier White Star games) used to access Portals is located on the coin door.
 

<center>

<gallery widths=300px heights=120px perrow=3 caption="DMD Screens during Various Tests in Portals ">
File:Stern WS test switch.JPG|<center>Switch test (similar to switch edge test in Williams speak)</center>
File:Stern WS test active switch.JPG|<center>Active switch test (similar to switch level test in Williams speak)</center>
File:Stern WS test ded switch.JPG|<center>Dedicated switch test</center>
File:Stern WS test lamp options.JPG|<center>Very flexible lamp test options</center>
File:Stern WS test single coil.JPG|<center>Coil test</center>
File:Stern WS test trough full.JPG|<center>Trough clear, but equally a good test for the trough and shooter lane switches</center>
File:Stern WS test trough 3 in trough 1 shooter.JPG|<center>Advancing through trough clear</center>
</gallery>
</center>

=====Setting Free Play=====
 

===Coin Door Switches===
[[File:Stern coin door buttons.JPG|300px|left|thumb|Coin door Switches Located Inside a White Star Game (Monopoly)]] 
Most White Star games have two switches located on a bracket inside the coin door (hinge side). The upper switch is the memory protect switch. This switch is used so that nothing can be written to the memory, unless the coin door is open. The memory protect switch is not part of the switch matrix, nor is it one of the dedicated switches. Although it does connect to the CPU / Sound board via the same connector as the dedicated switches, its state is processed by a different chip (U213) versus the dedicated switches (U206). 

The lower switch is an interlock style "kill" switch. This kill switch is used to kill all power to the solenoids, when the coin door is opened. Since it is an interlock style switch, it can either be depressed (when the coin door is closed), or it can be extended outward to turn the switch on. To extend the switch to the on position when the coin door is open, grasp the switch, and gently pull it out to the lock position. 

The kill switch is a double pole switch. Wiring to one pole of the kill switch is BLK-YEL and BLK-YEL, while the other is RED-WHT to WHT-RED (yes, the colors do not match!)
 

== Problems and Solutions ==

=== Power Problems ===
===Fuse Table===
[[File:WhiteStarFuseTable.jpg|400px|left|thumb|The typical fuse table. This table appeared in the Stern Sopranos manual.]] 

=== MPU boot issues ===

Damage resulting from alkaline corrosion is the most prominent reason for the MPU to fail to boot.

If the GI lamps are blinking at about a 1Hz rate, this means that the MPU is not booting and that the I/O Driver board is sending a reset pulse to the 68B09E on the CPU/Sound board.

The following can be examined:

*Alkaline corrosion
*Inter-board ribbon cable fault inhibiting the reset of the CPU/Sound board watchdog timer DS1232. The timer is reset via signal DRV0, a lamp matrix signal.
*Failed ROM. Note that the ICs on WhiteStar CPU/Sound boards are ALL installed notch down. Installing a ROM upsidedown and powering on immediately destroys the ROM.

==== Relocating the Battery from the MPU board ====
[[File:WhiteStarAlkalineDamage.jpg|300px|thumb|left|The aftermath of batteries which leaked. This board is beyond repair, and good only for salvage parts.]]
Relocating the 3xAA batteries off the MPU board or installing other alternatives for memory retention is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. 

One option is to install a remote battery holder, and place the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) components of the MPU board. Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually. 

Another option is to install a memory capacitor. This method is considered to be better than a remote battery holder, because memory capacitors are not prone to leakage like alkaline batteries. The only drawback is that the memory capacitor has to be properly recharged to be effective. If a game has the potential of sitting dormate without being turned on for extended periods (typically months), the memory capacitor may not hold the memory. 

A third option is to install a lithium battery with a battery holder. Lithium batteries are much less likely to leak than alkaline batteries, and they do not need to be recharged.

Whatever you do, GET THE BATTERIES OFF THE BOARD! It's not a matter of if they will leak, it's a matter of when. WhiteStar boards are pricey to replace, and repair is difficult/expensive/even impossible due to the very fine traces used on the board. 

[[File:WhiteStarRemoteBatteryHolderAnnotated.jpg|300px|thumb|left|A White Star MPU Board with Remote Battery Pack Connected. The Positive (+) terminal is circled. D200 and D201 are highlighted inside the rectangle. Note that the battery installation date is recorded with a Sharpie. Also note the long wires, allowing the holder to hang well below the backbox boards, another precaution for leaky batteries.]] 
Adding a connector between the battery pack and the MPU board is a good idea. In doing this, the battery pack can easily be removed from the MPU board. Plus, if the batteries are forgotten, and do leak, the MPU board may not have to be removed to add another battery pack. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is available, a jumper can be soldered in the first battery position. Likewise, a diode can be placed in this position instead. Using a diode instead of a jumper will prevent the batteries from being charged and 'cooked' by the game if blocking diode D201 on the MPU board fails. Keep in mind that a second (redundant) diode added to the circuit will reduce the backup voltage to the RAM memory by .5 to .7 volts. Install a 1n4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the (+) terminal marking on the MPU board, and away from the battery pack. 

On the MPU, solder the battery cables: positive (red wire) to the "+" pad and ground (black wire) to the "-" pad.

Since the MPU board is already out, another good practice is to check the D201 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. Alkaline batteries do not like being charged. They will heat up, and fail rather quickly. In worse cases, the new batteries can even leak or explode if charged. Testing the D201 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D201 diode with a 1N5817 (a 1N4004 will work in a pinch), or add a redundant 1N4004 to the battery pack. Once again, if a second (redundant) diode is added to the circuit, it will reduce the backup voltage to the RAM memory by .5 to .7 volts 

Testing the D200 diode is a good idea too. The D200 (1N5817) diode is used to keep the backup batteries from powering the complete MPU board when the power is off. A symptom of a failed D200 diode are batteries which deplete rapidly.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the '''VBATT''' test point on MPU board. All battery packs are pretty cheaply made, and failures "out of the box" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:White Star Mem Cap.JPG|300px|thumb|left|Installation of a Memory Capacitor]]
A memory capacitor is a great choice for memory retention, provided that the game will be turned on more frequently than not. If the game will not be turned on for several months, the memory cap may not stay charged. In turn, the memory may not be retained. 

It is recommended to use a 1F (Farad) 5.5v memory capacitor. The lead centers on a common, button memory cap are shorter than the "+" and "-" through holes where the factory battery holder was installed. To overcome this, solder a short wire onto the negative lead of the cap. Then, bend the lead at a 90 degree angle, so it is now parallel to the bottom of the memory cap. Place the positive lead of the memory cap into the "+" of the board, and then place the wire from the negative lead into the "-" of the board. Solder both leads in place. 

Please note that when using a memory cap, the D201 diode must be removed (or jumped), and a 0 ohm jumper or a 100 ohm resistor (or similar value) should be installed. This purpose of removing the D201 diode is so the memory cap can be properly charged when the game is on.
 

==== Repairing Alkaline Corrosion ====
[[File:WhiteStarInsidiuosCorrosion.jpg|300px|right|thumb|Corrosion can hide in many hard to find places.]]
Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the batteries are mounted on the top of the board with plenty of board beneath it for the corrosion to leach onto. Components well below the battery holder are often damaged.

Remember, battery corrosion is alkaline. Harkening back to the dim and distant past, remember your Chemistry 101. Alkaline is neutralized with acid. Most commonly used is vinegar, since it is an acid. Diluting the vinegar to half strength by adding an equal amount of water (50/50) is a good idea to prevent adverse impact to adjacent areas of the board.

[[File:WhitStarAlkalineCorrosion-1.jpg|300px|left|thumb|This MPU sustained alkaline damage. Sockets for the 68B09E processor and the 6264 RAM have been removed.]]
[[File:WhitStarAlkalineCorrosion-2.jpg|300px|right|thumb|More components removed, the alkaline damaged traces sanded, and the damaged area treated with 50/50 vinegar and water.]] 
Argh! The MPU pictured at left has sustained alkaline damage. In this case, the damage was repairable. Most of the time, alkaline damage to White Star MPUs is more substantial and beyond economical repair.
 

[[File:WhitStarAlkalineCorrosion-3.jpg|300px|left|thumb|Bare copper traces tinned.]]
[[File:WhitStarAlkalineCorrosion-4.jpg|300px|right|thumb|All components (or sockets) reinstalled, and nearly ready for test.]] 
The completed board shown on the right took a few hours to cleanup, repair, verify, and game test.
 

[[File:StarShipTroopersMPU.jpg ‎|1100px|center|thumb|A StarShip Troopers MPU, with widespread alkaline corrosion abated professionally.]]
[[File:WhiteStarComponentLayout.jpg|1100px|center|thumb|Components in WhiteStar Corrosion Area. Click to enlarge. Note: "104" refers to .1uf ceramic cap, 470 refers to 470pf cap.]]

===== Continuity Chart of Pin Outs in Battery Damaged Area =====
Just below the battery holder, the CPU EPROM and RAM both reside. Both of these chips and their sockets are susceptible to battery damage. Provided that the alkali damage breached the chip sockets, it is always best to check continuity on the new work performed. Below is a chart of the pin outs between the RAM (U212), EPROM (U210), and CPU (U209) chip. This chart will hopefully come in handy should repair of this area is necessary.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Signal
!68B09E Pin (U209)
!ROM Pin (U210)
!RAM Pin (U212)
!PAL Pin (U213)
!Other
|-
| Vcc ||7||32||28||20||
|-
| GND ||1 & 39||16||14||10||
|-
| A0 ||8||12||10||||
|-
| A1 ||9||11||9||||
|-
| A2 ||10||10||8||||
|-
| A3 ||11||9||7||||
|-
| A4 ||12||8||6||||
|-
| A5 ||13||7||5||||
|-
| A6 ||14||6||4||||
|-
| A7 ||15||5||3||||
|-
| A8 ||16||27||25||||
|-
| A9 ||17||26||24||16||
|-
| A10 ||18||23||21||15||
|-
| A11 ||19||25||23||8||
|-
| A12 ||20||4||2||9||
|-
| A13 ||21||28||26||3||
|-
| A14 ||22||29||---||2||U211-2 (XA0)
|-
| A15 ||23||3||---||1||U211-5 (XA1)
|-
| A16 ||31||13||11||||U211-6(XA2)
|-
| A17 ||31||13||11||||U211-9 (XA3)
|-
| A18 ||31||13||11||||U211-12 (XA4) - Prior to rev. E boards
|-
| D0 ||31||13||11||||
|-
| D1 ||30||14||12||||
|-
| D2 ||29||15||13||||
|-
| D3 ||28||17||15||||
|-
| D4 ||27||18||16||||
|-
| D5 ||26||19||17||||
|-
| D6 ||25||20||18||||
|-
| D7 ||24||21||19||||
|-
| /ROMCS ||---||22 (BSMT2000) 24 (Atmel)||---||19||
|-
| /RAMCS ||---||---||20||18||
|-
| /E ||---||24 (BSMT2000) 22 (Atmel)||22||4||U1-6
|-
| /CS ||---||---||26||||Q9-1 - rev. D or JP1 (8K) - rev. E
|-
| R/W ||32||---||27||7||
|}

 

==== Connecting a logic probe to the MPU ====
[[File:WhiteStarConnectingALogicProbe.jpg‎|300px|thumb|left|Connecting a logic probe to a Sega/Stern White Star MPU]]
[[File:WhiteStarModifiedConnectingALogicProbe.jpg‎|300px|thumb|right|Connecting a logic probe to a Stern White Star (Modified) MPU]] 
Connecting a logic probe to a Sega/Stern White Star board set (left) is simple. 
Both 5V and Ground test points are made available on the MPU board.

Connecting a logic probe to a Stern White Star (modified) board set (right) is simple too, but a 5V connection point isn't provided. 
Connect the positive lead of your logic probe to either side of the inductor labeled FB1.
 

==== Using a PC Power Supply For Bench Testing ====

===Low 5VDC and Game Resets===
Some symptoms of a game which repeatedly resets upon boot up are:

#General illumination lamps will repeatedly flash on and off (the GI relay can be heard clicking on / off).
#The DMD will display the initial boot screen, show the display ROM revision number, go blank, and then repeat this process.
#The sound board (depending on the age of the game) may only emit a "blip" sound or a shorter than usual initial sound clip.

In some of the above instances, the DMD display may or may not light up at all. 

The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer. 

U413, which is located on the CPU / sound board next to the reset button, is a [https://datasheets.maximintegrated.com/en/ds/DS1232.pdf Dallas Maxim DS1232] monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC. 

If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. Another location to measure the +5VDC is right on the metal casing of the LM338K regulator (U19), If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338K regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto transmitter board may be at fault. 

Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. The +5V test point on the CPU / sound board is located just to the left of the 6809EP CPU chip (U209) on the board. If the voltage drastically differs between the measurement of the I/O Power Driver Board and the CPU / sound board, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board. 

==== DS1232 Voltage Watchdog ====
[[File:WhitestarDS1232Pin3Clipped.jpg|left|thumb|300px|While this looks to be an error, it's actually a factory modification to the DS1232 reset generator. While this part is on the CPU/Sound board, there is an identical part on the driver board, which will have pin 3 clipped also. On the CPU pin 2 (Time Delay Set) might also be clipped. Pin 2 and 3 are left unconnected from the factory on the WhiteStar (modified) CPU/Sound board.]]
Both the WhiteStar MPU and Driver boards employ a DS1232 voltage watchdog. From the Sega and Stern factory, pin 3 is almost always clipped. Pin 3 is used to select the voltage tolerance the chip is to enforce.

A discussion regarding the proper connection of pin 3 was offered by John Robertson on rec.games.pinball, and is copied below.

Begin discussion...

You read it here (rec.games.pinball) first!

Looking into a problem with our Roller Coaster Tycoon where the game
would cut out the lights and coils for up to a second at random
intervals. This would happen perhaps once or twice every day or two.

Digging into the game I noticed that the Dallas supervisor chip used in
both the original Stern and the Rottendog replacement Driver Board both
left pin 3 (LOP) floating. Now this pin is there to select the Vcc
tolerance - if grounded it is 5% and if tied to Vcc it is 10%. However
the schematics now show pin 3 as floating.

Sega Service Bulletin SB112 (June 7, 1999) had recommended cutting pin 3
(to floating) on both Dallas DS1232s (MPU & Driver PCBs) where the
factory (at that time) had connected pin 3 to Gnd (5%). Sega, then Stern
continued this practice of either cutting or leaving pin 3 floating.
Rottendog also did this on their replacement board.

http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf

I was curious what would happen and if this idea of cutting the leg or
leaving it floating was recommended by Dallas. So I pulled up both the
original Dallas documents and the Maxim Application Note and in neither
case did they suggest that pin 3 should be floating - no connection.They
said it was to be connected to either Gnd or Vcc.

https://datasheets.maximintegrated.com/en/ds/MAX1232.pdf

https://pdfserv.maximintegrated.com/en/an/AN581.pdf

I then asked Maxim (who now make Dallas Semi chips) to comment on what
happens when pin 3 is floating - they replied today (Nov 25, 2019):

Thank you for contacting us.

It is not recommended to leave the TOL pin open since it is a digital
input and noise can make it oscillate, there is no internal pulling
resistor, so please do indeed connect it to GND or Vcc.

Regards,
Javier Monsalve
Maxim Applications

We had already tied pin 3 to Vcc (+5) as of Nov 23, 2019 to check my
assumption that floating was wrong, and the intermittent cutting out
problems had indeed disappeared!

The game has been running for days now with no hiccups and we shall be
leaving it running at least one more day before sending it to its new
home. We are monitoring the Vcc with a Mooshimeter logging 5V, to see if
Vcc drops below any reasonable threshold and a Heathkit logic probe
monitoring the R (pin 5) of the DS1232 as the Heathkit logic probe
stores momentary state changes (turns on a 'memory' LED).

Therefore, based on our tests, and the advice from Maxim, the
manufacturer of the DS1232 IC Supervisor chip, we can now say that you
need to tie pin 3 of the DS1232 to Vcc! Do NOT leave it floating as per
Sega Service Bulletin SB112!

Hope this helps!

John :-#)#
 

[[File:RottenDogDS1232SolderBridge.jpg|left|thumb|300px|An (probably) intentionally created solder bridge on a RottenDog power/driver board, bridging pins 3 and 4 on the DS1232 voltage watchdog, selecting 5% (4.75VDC) tolerance.]] 
RottenDog WhiteStar power/driver boards may have a solder bridge across pins 3 and 4 of the DS1232 voltage watchdog. This is done to prevent pin 3 from "floating" and instead actively select the watchdog voltage.

Quoting Ed from Great Plains Electronics on PinSide...

It appears pin 3 (voltage tolerance pin) was left floating on their (RottenDog) design. That input is supposed to be tied high (reset at 4.5V or 10% VCC tolerance) or tied low (reset at 4.75V or 5% VCC tolerance) and should never be left floating. Adding the jumper from pins 3 to 4 selects the 5% tolerance. If the 5V line dips below 4.75V then your board will reset (which is what it is supposed to do with that setting).

Jumpering pin 3 to pin 8 (5VDC) selects the 10% tolerance.
 

[[File:DS1232MPU.jpg ‎|left|thumb|300px|The MPU DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
[[File:DS1232Driver.jpg ‎|right|thumb|300px|The Driver board DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
In these two images, the DS1232 voltage watchdog, pin 3, has been tied to a convenient source of 5VDC, selecting 10% (4.50VDC) tolerance.
 

[[File:WhiteStarModifiedDS1232.jpg ‎‎|left|thumb|300px|The DS1232 on a WhiteStar (modified) MPU, and connection that can be made.]] 
Some (if not all) WhiteStar (modified) MPUs leave pin 3 of the DS1232 floating. A trace from pin 3 leads to a through-hole for an unstuffed part. This through-hole can be exploited by adding a jumper as indicated in the picture at left. Installing this jumper configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance.
 

[[File:WhiteStarDriverRevGDS1232Connection.jpg ‎ ‎‎|left|thumb|300px|The DS1232 on a WhiteStar Revision G Driver Board, and connection that can be made to 5VDC, selectiong 10% tolerance or 4.5VDC.]] 
Revision G of the WhiteStar Power/Driver board leaves pin 3 floating even though R257 is provided to jumper the pin to ground. A better option is to jumper pin 3 to 5VDC which configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance. An easy method to achieve this is shown at left. This method uses the available through hole at R257.
 

==== Poor or Damaged Sockets Cause Reset ====
[[File:WhiteStarCrappySocketAnnotated.jpg‎|300px|thumb|left|A damaged EPROM socket from a Sega/Stern White Star MPU]] 
A damaged socket for either the game ROM or the 6264 RAM can cause a game to continually reset. This happens because the CPU can not fetch and execute instructions from the game ROM, or it is unable to read/write data to/from the RAM correctly. A simple replacement of damaged OEM sockets sometimes corrects a reset issue.
 

====Game Resets with DMD Controller Board Connected====
This may be a bit of an anomaly, but it is worth mentioning. If when the DMD controller board is connected without the data line ribbon cables, and the game continues to reset, replacement of BRDG21 may be required. 

In one particular instance, a game was resetting continually with only the +5v / ground connection connected to the DMD controller board. If the board was not connected, the driver board would output ~+5VDC. If the DMD controller board was connected, the driver board's logic line would dip down to around +4.85VDC. Logically speaking, this type of symptom somewhat points to the DMD controller board having issue. However, the end result was replacement of BRDG21 per Stern tech support. 

It is worth mentioning that the bridge rectifier did test correctly (using a DMM in diode test) both in circuit and out of circuit, but these tests were conducted while the bridge was not under load. 

===Solenoid/Flasher, and Controlled Lamp problems all at the same time===
[[File:CorrodedWhiteStarHeaderPinsCropped.jpg|300px|thumb|right|Corrosion on driver board header J1, prevented data bus signals from reaching the drive buffer chips. Image courtesy of PinSider JamesH007]] 
If the game is experiencing issues with multiple devices (coils, flashers, controlled lamps) that are controlled by the driver board, and those devices are "separated by 8 bits", there is a good chance that the data bus that connects to each of the 74HCT273s driver chips on the driver board has lost continuity somewhere between the associated MPU board dual row connector and the driver chips.

This can include:
*the dual row header on the MPU board
*the ribbon that connects the MPU and driver board
*the dual row header on the driver board
*the traces leading from the dual row header on the driver board to the 74HCT273s

The image at right shows a corroded connector which led to inoperative coils driven by Q3, Q11, Q19 and Q27 (note the gap between these parts is 8 transistors, the width of the data bus).
 

===Solenoid problems===

====Game Notes====
*NASCAR solenoid test swaps the order of output for coils 25 and 26. While the display calls out coils 25 and 26 correctly, in fact coils 26 and then 25 fire.

[[File:NASCAR-1.jpg‎|300px|thumb|left|NASCAR shooter lane switch with wireform correctly in place.]]
[[File:NASCAR-2.jpg‎|300px|thumb|right|NASCAR shooter lane switch with wireform bent/stuck and switch closed.]] 
Stern NASCAR, and possibly other games, use a switch in the shooter lane to detect the presence of a ball. If the switch is closed, and the auto-launcher coil fires to launch the ball, and the game doesn't detect that the switch has opened after firing the shooter lane auto-launcher, then the game assumes that the auto-launcher has malfunctioned in some way, and reports an error on the DMD.
 

====Testing MOSFETs and TIPs====
[[File:IO_test_points.jpg‎|300px|thumb|left|Driver Test Points TPL1 above Q16 (left) and TPL3 above R302 (right) are used to fire the transistors on the driver board.]] 

The Sega/Stern I/O Power Driver Board contains 32 driver transistors on the bottom right of the board. Transistors Q1-Q16 are MOSFETs – either 20N10Ls or P22NEs. These are used to drive high current coils like the flippers and other heavy loads. These are connected to devices through J8 and J9. Transistors Q17-Q32 are TIP 122s and are used for driving low power solenoids such as flash lamps. These are connected to devices through J6 and J7. 

All of these drivers are computer controlled directly from the CPU board through a flip-flop on the driver board. Q1-Q8 are controlled through U1 on the driver board, Q9-Q16 are controlled through U2, Q17-Q24 are controlled through U3 and Q25-Q32 are controlled through U4. Each one of these chips is selected by the address decoder at U204. There is another address decoder at U205 and both of these decoders must be working properly for the I/O board to function. 

It is possible to test the driver transistor and the solenoid in the circuit from the driver board. Above Q16 on the driver board is a test point marked “TPL1 FET”. Not a lot of people know what this is for. Per the manual: “This will apply 3.4v to the gate of the MOSFET transistor thus switching it on.” You’ll notice that the bank of resistors from R1 to R16 have a white stripe on one side closest to the MOSFETs. By using a jumper wire from TPL1 to the lug of each resistor in the white band, you can fire the coil associated with that resistor/MOSFET. Each resistor number corresponds with the same MOSFET number. So R1 fires Q1, R2 fires Q2, etc, etc. TPL1 is for testing all the FETs from Q1 to Q16. 

If you look in that same photo above R302, you will notice “TIP TPL3”. This serves the same purpose as TPL1 except for the TIP transistors on the driver board Q17-Q32. By jumping from TPL3 to the leg of the resistor in the white band, you can test each of the TIP122s and their associated circuitry. This is a useful diagnostic step if the machine will not fire a coil in self-test or during a game. If you can fire the transistor with this test, you know the problem is with the computer control circuitry for the solenoids. However, if it doesn’t fire, it could be a problem with the transistor or the associated components in that solenoid circuit. 

If one of Q1-Q16 is bad, it is best to replace it with an IRL540N (see below). If one of Q17-Q32 is bad, it is best to replace it with a TIP102. 
=====Screening Error On the Board=====
You might notice in the photo (prior section) that the white stripe is on the lower leg closest to the transistors of R1-16 and R25-32, but there is no white stripe on R17-24. Instead the stripe is on the lower leg of the resistors R200-R207. This is a screening error on the board but electrically match to the correct legs of resistors R17-24. As an example, if you want to test Q17, touch the leg of resistor R200 that’s in the white strip and Q17 should fire. The same holds true for R201/Q18, R202/Q19, etc etc. 

====Can an IRF540 replace a P20N10L, P22NE10L or an IRL540?====
[[File:IRL540vsIRF540.jpg‎|300px|thumb|left|Danger Will Robinson...the IRF540 installed at Q6 shown above, is the wrong part. The original 22NE10L should be replaced with an IRL540, like the one to it's immediate right.]] 
No.

The White Star driver board first used STP20N10L FETs to drive high current circuits, like solenoids. When they were discontinued later boards used the STP22NE10L. Since the 22NE10L is obsolete and even the current replacement, the
STP40NF10L is hard to find, the IRL540 or IRL540N are the recommended replacements. If available get the IRL540N because it has a higher drain current rating of 36A.
 While the drive specs of the IRF540 seem comparable, they are not. Using an IRF540 as a substitute can cause the associated coil to lock on, toast the coil, then blow the FET. The L in all of the original parts indicate that it is a logic level FET.

Per a good friend of Pinball, Ed Krzycki, via [http://groups.google.com/group/rec.games.pinball/browse_frm/thread/de777f6eec98a687/330e0d47fde12c6f?hl=en&lnk=gst&q=irf540# RGP post]...

''Nope -- an IRF540 is not a good sub for the IRL540 or 22NE10L.''

''The "L" parts have TTL compatible gate voltages. A TTL gate has a minimum high level output voltage of about 2.4 volts. To turn on any N-channel MOSFET transistor - the Gate voltage must be sufficiently high enough as listed by the spec sheets VGS(th) voltage.''

''The IRL540 requires a Gate threshold voltage of 1 to 2 volts. A TTL part exceeds this voltage so a TTL gate's high level output would guarantee the gate would turn completely on. The IRL540 is guaranteed to have "turn on" and "turn off" voltages that are compatible with a standard TTL device.''

''The IRF540 requires a Gate threshold voltage of 2 to 4 volts. A TTL gate *might* turn this part on if the specific part being used has a threshold in the 2 to 2.4 range. If the specific part being used has a threshold closer to the 4 volt range then the MOSFET probably won't turn on properly or fully. The IRF540 *might* work or it might not work. And no guarantees that a working part would remain working if ambient temperature changes.''

''Another aspect to an IRF540: An IRL540 operates more as an on-off switch but an IRF540 does not. Depending on voltages, an IRF540 can operate as an on-off switch and can also operate anywhere in between on and off (half on) depending on input voltage. If the TTL device cannot quite drive the gate voltage high enough then the MOSFET may end up partially conducting. This can have different results depending on how much it is turned on.''

''The 22NE10L has similar characteristics to that of the IRL540 as far as gate threshold voltages.''
 

====Adding a Real Knocker to White Star Games====

Some White Star games (like Starship Troopers) are not equipped with a real, old fashioned, knocker. We all love knockers, don't we?

To add a real knocker to your White Star game, follow this procedure.
Note: in this procedure, we locate the knocker in the head, attempting to increase the knocker's impact. For cabinet installation, take advantage of the wiring already provided for the European Token Dispenser.

[[File:AddingAKnockerBigPicture.jpg|left|300px|The objective...]] 
In the picture at left, we show all the components necessary to add a knocker. The new knocker is circled, top left. We've used an in-line connector along the wiring, also circled, lower left. The power and ground connections are noted by the rectangles.
 

[[File:SSTManual.jpg|thumb|left|300px|A snippet from the Sega Starship Troopers manual showing coils, and in particular, coil 8, the European Token Dispenser.]] 
First we need note that the European Token Dispenser solenoid drive is unused in domestic (USA) games. Coil power and drive connections are wired into the game. They can be found in the cabinet bottom. We could simply connect the knocker to that connection, but in this example, we mount the knocker in the game head.
 

[[File:SolenoidPowerConnection.jpg|thumb|left|300px|Adding a wire to provide the knocker with 50V power.]] 
Here I've stuffed another wire (yellow with purple tracer) on top of the solenoid power supply at J10, pin 5. This wire will eventually be connected to the banded side of the knocker coil.
 

[[File:SolenoidGroundConnection.jpg|thumb|left|300px|Adding a wire to provide a path to ground for the knocker, typically called the solenoid drive.]] 
Here I've stuffed another wire (purple with black tracer) on top of the solenoid 8 drive connection at J8, pin 9. This wire will eventually be connected to the non-banded side of the knocker coil.
 

[[File:SegaKnockerInSitu.jpg|thumb|left|300px|The new knocker, screwed to the cabinet upper left corner...not much room there. Also add the "strike plate" to the cabinet side.]] 
Of course, you need to procure the actual knocker hardware, and connect it as shown in the prior pics. In the picture at left, we've added a Sega knocker assembly and strike plate.
 

The last thing to do is to enter the game adjustments and turn the electronic knocker sound and the European Token Dispenser settings to off. On Starship Troopers, Enter Portals, Adjustments, Sega, and then adjustment 33 (Knocker Volume - set to OFF) and adjustment 40 (European Token Dispenser - set to OFF).

That's it. Enjoy those knockers!
 

===Flasher problems===
[[File:SSTFlashers.jpg|300px|left|thumb|One of the 4 sets of 4 colored flashers on Starship Troopers.]] 
Starship Troopers, Apollo 13 and perhaps other White Star games, drives 4 flash lamps via a single TIP-122 transistor. The TIP-122 is rated for a maximum drain of 8A (and a working current of 5A) while 4 flash lamps typically have a cold resistance of under 1 ohm (0.8 ohm is typical including wire and socket resistance.) While incandescent lamps only present their minimum resistance when extinguished (they are negative-temperature coefficient devices by design) the surge drain when these lamps are lighted radically exceeds the transistor's rating and is likely to damage or destroy it over time.

These channels should be replaced with TIP-102s (15A peak drain) or replace two (or more) of the flash lamps with LEDs to bring the drain in-line with the maximum ratings of the TIP-122.
 

===Controlled lamp problems===

==== Overview of The Lamp Matrix ====

The WhiteStar lamp matrix is an 8 column, 10 row lamp matrix, powered by 18V.

Lamp matrix power is derived from 13VAC presented to the I/O Driver board at J17, pins 8 and 9, via the transformer secondary winding. The circuit is fused by F22, an 8ASB fuse. BRDG20, a 35A bridge rectifier creates the 18VDC which is then smoothed by two 15,000uf/25V filter capacitors at C201 and C202. Of interest is the combined filtering of 30,000uf matches the original lamp matrix filtering capacity of old Williams System 3 games. When lit, LED202 indicates the presence of 18VDC power.

A blown fuse at F22 probably indicates a shorted bridge at BRDG20.

[[File:WhiteStarLampMatrixComponents.jpg|300px|thumb|left|Components of the WhiteStar I/O Driver Board Lamp Matrix]] 
Lamp rows are implemented with STP19N06L or STP20NF06L FETs, controlled by the 74HCT273 at U6 on the I/O Driver Board. 39K current limiting resistors protect the 74HCT273 from sinking too much power. The 74HCT273 is strobed (enabled) via the LMPSTB which originates at U205 (a 74LS138 at U205, pin 15).

If a STP19N06L (or STP20NF06L) transistor fails, it can be replaced with an IRL530N or an IRL540N. However, using an IRL530/540 has been known to create "ghosting" or "always dimly lit" behavior in the lamp row. If the original part can be obtained, this possibility can be eliminated. An IRFnnn (i.e. IRF530) or BUZ22 can not be used as a replacement.

Lamp columns are implemented by the obsolete VN02N PENTAWATT solid state relay (5 legs). They are controlled by the 74HCT273 at U18 on the I/O Driver Board. 18VDC is "strobed" to the lamp column headers. The 74HCT273 is strobed (enabled) via the LMPDRV which originates at U205 (a 74LS138 at U205, pin 13).

A replacement for the obsolete VN02N has not been identified. In addition to the WhiteStar I/O Driver board, VN02Ns were used on Capcom driver boards.

Be sure to check the fuse clips for the controlled lights. They go bad from either metal fatigue or they crack. This causes poor, erratic, or no connection with the fuse and thus, no lights.
 

===General illumination problems===

The four general illumination (GI) strings are turned on and off via the relay on the power driver board. On the White Star board the relay is controlled via transistor Q200 and latch U206. This is more or less the same setup found in earlier Data East and Williams System 11 games where the relay is located on the power supply or PPB board. These relays seldom fail. The part number for the 24VDC relay is any of the following:

*LB2-24DP (Great Plains Electronics number)
*190-5002-00
*LY2-0-DC24
*FRL264 P024/02CK
*R14-11D10-24P

If one or more GI strings are out check fuses F24 to F27 and then connector J15. Although WhiteStar GI connectors don't burn and tarnish like early Bally/Williams WPC GI connectors, checking both the male and female connectors at J15 is worthwhile.

[[File:Sega-whitestar-pdb-gi-error.jpg|300px|left|thumb|A leaky capacitor at C32]] 
If the GI goes out during game play and turns back on when opening the door, check capacitor C32 on the power driver board. It normally has nothing to do with either the GI circuit or the relay voltage but a leaking cap can short the trace coming from Q200 to ground. In this case the relay pulls in and disconnects the GI. When you open the door the game cuts the coil power for the relay coil and the GI turns back on. This has been observed in a Twister game.

The fuse clips for the GI circuits can fail, either by cracking or by losing their springiness.
This causes poor or no contact with the fuse and intermittent or no power to the associated GI string of lamps.
 

=== Switch problems ===

==== Overview of the Switch Matrix ====

The WhiteStar switch matrix is the typical 8 by 8, 64 switch matrix. As with other switch matrix implementations, isolation diodes are used on every switch in the matrix.

Switch columns (strobes) are connected to CN5 on the top edge, left side, of the CPU/Sound board. The columns are controlled by the 74HCT273 at U203 which sequentially controls an array of 8 2N3904 transistors. These transistors switch the 5VDC, normally held high via 560 ohm pull up resistors R423 through R430, to ground.

If a switch in the matrix is closed, the ground driven through the switch column will be presented at the row associated with the column/row intersection of that switch.

Switch rows (returns) are connected to CN7 on the top edge, right side, of the CPU/Sound board. 5VDC pull up resistors (560 ohms at R401 through R408) normally hold the switch row high. However, when the ground is presented at the row header of CN7, that 5VDC is pulled to ground. The signal is compared to 5VDC by the LM339 comparators at U400 and U401 with the result presented the the 74HC245 at U205 and then read via the 68B09E's data bus.

Note that the WhiteStar LM339 comparison implementation differs from the Bally/Williams WPC implementation which also uses 5VDC as a comparison voltage (reference) but compares that 5VDC to either 12VDC (open switch) or ground (closed switch).

==== General Switch Matrix Testing ====

[[File:WhitestarSwitchTest.jpg|thumb|300px|left|Testing Whitestar CPU/Sound board switch matrix circuitry with a jumper. A diode is not necessary.]] 
Like most modern game manufacturers, Sega/Stern games employ a switch matrix. The switch matrix circuitry on the CPU/Sound board may be tested (as pictured at left) by jumpering between switch row and switch column header pins while in switch test. This works with all versions of the Whitestar CPU/Sound board.

Note that some games, that do not use the full switch matrix, will fail to report a switch closure when jumpering row and column header pins for a switch that is shown as "not used" by the game. i.e. Sopranos does not use switch column 6. While a strobe is sent out on column 6, jumpering between column 6 and any row will not return a switch closure indication in switch test.

 

==== Playfield Switch Problems ====

===== Modular Stand Up Targets =====
The following Sega games employ unique playfield "Stand Up" targets:
*Goldeneye
*Twister
*Space Jam
*Star Wars Trilogy
*The Lost World Jurassic Park
*Starship Troopers
*Viper Night Drivin'
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park
*Playboy (used behind the "Peek-A-Boo" stand up)

They are self-contained modular targets, made by Happ Controls, that are quite easy to remove or replace. The target "faces" may be purchased separately and may be interchanged easily. The unit has a self-contained diode, like all switches that are sensed via a switch matrix. It also contains a small micro-switch, that the "tail" of the target face actuates. The "Achilles Heel" of this target system is the IDC connector. As with all IDC connectors, the wires can pull out fairly easily. 

Detailed disassembly / assembly instructions can be reviewed in [http://www.pinwiki.com/wiki/images/7/76/Stern-Sb110.pdf Stern Service Bulletin 110]. 

<center>
<gallery widths=250px heights=200px perrow=3 caption="Sega Modular Targets (from Starship Troopers)">
File:SegaTargetFullyAssembled.jpg|<center>An example target. The target "faces" are interchangeable.</center>
File:SegaTargetParts.jpg|<center>"Exploded" target parts. The gray switch part must be oriented correctly. Note the integrated diode just under the micro-switch, center/bottom.</center>
File:SegaTargetIDCConnector.jpg|<center>The Achilles Heel of a Sega target...the IDC connector.</center>
File:SegaTargetDisassembly.jpg|<center>The first step to disassemble a target. Slide the rear face of the target assembly up.</center>
File:SegaTargetTestingZero.jpg|<center>Testing a closed target switch, step 1. In diode test, with the switch closed, your meter should read 0 or null.</center>
File:SegaTargetTestingDiodeDrop.jpg|<center>Testing a closed target switch, step 2. In diode test, with the switch closed, your meter should read .5 to .7, the nominal voltage drop across a diode.</center>
</gallery>
</center>
 

=====Magnetic Reed Switches=====

[[File:Placeholder.jpg|thumb|300px|left|Sega Magnetic Reed Switch (from Space Jam)]] 
Starting with Space Jam, Sega introduced magnetic reed switches. This type of switch is a sealed, non-serviceable switch. Theory of operation of the reed switch can be reviewed in [http://www.sternpinball.com/upload/downloads/sb89.pdf service bulletin 89]. Replacement part number is 180-5145-XX.
 

=====Ball Trough Switch Problems=====
[[File:White Star Trough 18 Nut.JPG|left|thumb|300px|Typical Sega ball trough assy. using 1/8" screws heads]]
[[File:White Star Trough 316 Nut.JPG|right|thumb|300px|Typical Stern ball trough assy.using 3/16" screws heads]] 
As with any sub microswitch, the switches can become sporadic or fail over time. Another thing that can happen is the switch arm can break at its pivot point. This happens with this style of switch more frequently than other styles, because the metal arm is placed between two plastic ears. With nearly every other style of sub microswitch, the arm has the metal ears which go over plastic nubs on the switch body. The correct replacement switches are 180-5119-00 roller arm switches. Over the years Sega / Stern used both 1/8" and 3/16" screw heads on the screws which secure the trough switches. At this time, it is uncertain when Sega / Stern changed the screw size. 

[[File:Xcelite 18 Nutdriver.jpg|left|thumb|300px|Xcelite 1/8" Nutdriver used to remove screws from trough switches]]
[[File:DE Ball Trough Divots.JPG|right|thumb|300px|Ball trough assembly with divots. Although it's not a White Star game, Jurassic Park is used for this example.]]
There may be other issues, which appear to act like ball trough switch failures. One of the problems is divots in the ball trough itself. After many iterations of the balls slamming into the trough over and over, divots start to develop. This divots can keep balls from rolling down the trough assembly. In turn, the balls will not be closing the proper switches in the trough. The end result is a game that "loses its mind". If the balls are not where they are expected to be in the trough, the game cannot function as intended. 

A similar issue to divots in the trough is magnitized balls. This occurs primarily in games where a magnet captures a ball and holds it for a length of time. Some examples of games with magnets that hold the ball are Apollo 13, Goldeneye, Twister, Space Jam, and X-Files. This problem typically happends when two or more balls are grouped together in the trough. They will literally be held in place and stick to the trough. This happens to the balls located furthest from the ball trough VUK. To determine if a ball or balls are magnetized, remove the lower apron, and the top bracket over the trough. Gently place a non-metallic object between the balls to see if they separate themselves.
 

For ball trough switch issues pertaining to the opto boards, see the section [[#Two_Balls_Served.2C_Continuous_Balls_Served_to_the_Shooter_Lane.2C_or_the_Trough_VUK_Fires_Repeatedly | below.]]
 

====Opto Switch Problems====
With White Star games, opto switch pair closures are analyzed by the CPU in the same manner as leaf switch pairs or normally open (NO) microswitches. When a leaf or NO microswitch closes, the end result is identified by the CPU as a valid switch closure.

[[File:Sega_X-Files_Optos.JPG|left|thumb|300px|Two sets of opto pairs installed in a Sega X-Files ]]
If an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch.

The transmitter side is an ultra-red LED with a current limiting resistor. The receiver is an identical ultra-red LED. When light from the transmitter shines on the receiver LED, a small amount of voltage is "excited" in the LED. By using discrete components on the receiver side, that small voltage is detected and the appropriate signal is sent to the CPU via the switch matrix return (row). In this design, failure on the receiver opto side is more common. The transmitter LED will be lit (and visible with the naked eye), while the receiver LED will not be lit.
 

<center>
<gallery widths=300px heights=150px perrow=3 caption="Sega/White Star Transmitter, Receiver, and Opto 'Long Hop' Board Pair, as found on Starship Troopers. Note that the ultra-red LED on the transmitter side is not lit until power is applied. The receiver side never illuminates.">
File:SegaOptoTransmitter.jpg|<center>The opto transmitter side.</center>
File:SegaOptoReceiver.jpg|<center>The opto receiver side, with accompanying electronics. The red colored LED is a diagnostic aid to indicate a detected switch closure.</center>
File:SegaOptoAlignment.jpg|<center>An opto pair. The pair must be in perfect alignment or the opto switch will operate unreliably.</center>
</gallery>
</center>
 

This particular system is different than how Bally/Williams WPC CPUs handle opto pairs. WPC games employ infrared opto pairs.

Theory of operation for these circuits is described in the manuals. Sega/Stern have included some excellent, detailed, technical documentation within their manuals. [https://www.pinwiki.com/wiki/images/9/92/Sb67.pdf Stern Service Bulletin #67] includes detailed theory of operation of these opto switches. 

=====Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly=====
Common problems with some White Star games are:
# Two balls are served to the shooter lane.
# Balls are continuously served to the shooter lane.
# The trough VUK repeatedly fires, when there are no balls above the VUK trough plunger.

The first test is to determine if the balls are sliding down the trough. If they are repeatedly magnetized they tend to stick to the side of the trough and not slide down. Replacing the balls with will fix this. There are balls available which are low magnetic, but you can also line the floor of the ball trough with a thin sheet of PETG breaking the magnetic contact.

Depending on the exact circumstances, and the era of the White Star game, one or two of these symptoms can occur. The crux of the problem is either one or both of the two trough LED opto transmitters or receivers is failing. Rarely do the components on the trough opto boards other than the red LEDs actually fail though. And in most cases, it is not the LED itself, although, there are some instances when the problem is a failing LED. It is noteworthy that the issue is more common to the opto receiver side more so than the opto transmitter side. 

[[File:Stern WS test trough 1 in trough.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough]]
[[File:Stern WS test trough vuk up one ball.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough and One Ball Stacked]]
If the any of the previously mentioned symptoms are evident, the best approach is to first put the game into "Clear Ball Trough" mode via the Portal buttons on the coin door. Consult the manual documentation for details how to enter this test. Once all of the balls are removed from the trough, no balls should display on the DMD display. If either of the two images shown to the left are displayed on the DMD, and the ball trough no longer has any balls present, there is a problem with either the transmitting or receiving opto boards.<br=clear all>

The first thing is to observe the two red opto LEDs on the transmitting board. This board is located on the backside of the ball trough. If the transmitting LEDs are lit, there probably is not a problem with them. However, this is not always necessarily the case. Secondly, inspect the opto LEDs on the receiving board. To do this, the game will have to be turned off, and the receiving opto board removed via the three screws which attach it to the trough. Look for hairline cracks around the .100" angled header pin solder joints. Likewise, inspect the solder joints around the opto LEDs. If cracks are evident in any of these locations, remove, and apply fresh solder to these connections. Reinstall the receiver board, and observe the results. Conversely, if hairline cracks are not found, or if the same symptoms are still evident after reflowing solder joints, replacement of the LED optos is suggested. 

White Star games initially used MT5000UR ultra-bright red LEDs, while later games used TLRH180P ultra-bright red LEDs for both the transmitter and receiver boards. Both styles of LEDs have become expensive and fairly difficult to source. Great Plains Electronics offers the [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] as viable replacement for either original, factory LED. The only caveat is that both the transmitter and receiver opto LEDs must be replaced in pairs to ensure proper function. 

When replacing the opto LEDs, make certain the base of the LED is placed squarely on the PCB. An LED which is poorly installed may result in sporadic switch closures. 

[[File:DE Trough Ball Lock3.JPG|300px|left|thumb|Lock Ball Assembly (from Jurassic Park - used for illustrative purposes)]] 
Please note that a "Lock Ball Assembly" was employed in the trough design on early White Star games. The lock ball assembly is a unit, which was carried over from later Data East and early Sega games. It consists of a coil mounted horizontally above the left side of the trough VUK. This assembly was later removed presumably either due to cost factors, or so this coil assignment could be used as a playfield coil feature elsewhere instead. 

If a lock ball assembly is used in the game, and trough opto failure has occured, the symptom will more than likely be that the trough VUK will fire repeatedly without a ball present above the VUK plunger.
 

=====Phantom Opto Switch Closures=====

Similar to the discussion above, "Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly", other opto pairs in the game may fail over time and become unreliable. Usually this manifests as phantom switch closures. Games like Starship Troopers that use an opto pair for both the left and right orbit shots may score the orbit shot randomly or even continuously. If the "long hop" opto assembly is removed, you may find that the opto pair registers correctly if the optos are aimed with great accuracy at one another. However, the slightest misalignment (like flexing the PCB) will cause the opto pair to register a "hit".

The correction for this is again to replace the original MT5000UR or TLRH180P ultra-bright red LEDs, with [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] LEDs from Great Plains Electronics.
 

===Display problems===
A few of the many possible display problem root causes are...
*Failure in high voltage power supply
*Failed Dot Matrix Display
*Failed ribbon cable
*Failed power connector on display driver board
*Failed 74LS374 buffer IC on the MPU board

Each possible root cause is discussed below.

==== Measuring High Voltages for the DMD Display ====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|300px|thumb|left|Testing DMD Controller voltages at the display. Note: This picture is a Williams game, but the concept is the same.]] 
To test for the voltages necessary for the DMD to operate, first open the backbox, and rest the DMD panel face down on the glass. Or, if the game has a "Showcase" style head (i.e. StarShip Troopers), swing the panel open to gain access to the HV connection to the DMD. The simplest place to test the voltages is at the display end of the power wire bundle as shown in the picture. SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you! 

The dot matrix display needs three voltages to operate, nominally -112, -100, and 62 VDC. All three voltages must be present for the display to operate correctly.

Place the black lead of the DMM under the ground braid in the game's head or use clip leads to secure the black lead to ground. Remember, you are working one-handed, so this becomes a necessity. Place the red lead of your DMM on each of the pins supplying power as shown in the picture. As long as there is a 12VDC difference between the Anode and 12VDC offset voltages, your DMD controller is providing correct voltage levels.

{| class="wikitable"
!Function
! Pin 
! Spec 
! nominal voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>-120V</center> || <center>'''-112V'''</center> ||
|-
|  12VDC Offset  || <center>2</center> || <center>-100V</center> || <center>'''-100V'''</center> ||  Must be 12V less than anode voltage. Will be about 20V less than anode voltage if display not connected
|-
|  Key || <center>3</center> || || ||
|-
|  Ground || <center>4</center> || || ||
|-
|  Ground || <center>5</center> || || ||
|-
|  5VDC || <center>6</center> || <center>5V</center> || <center>'''5V'''</center> ||
|-
|  12VDC || <center>7</center> || <center>12V</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>60V</center> || <center>'''62V'''</center> ||
|}

If the high voltages are off by more than a few volts, turn the game off, disconnect the power connector at the HV Power Supply, and test the voltages at the HV Power Supply male header pins. If the voltages return to nominal values, the zener diodes on the power supply are probably OK but the resistors and transistors around them are suspect. As shown in the table above, if HV power is not connected to the display, the nominal 12VDC offset will be about 20VDC.

Note that a failing or failed DMD display glass can drag these voltages down. Before you begin any work on the HV Power Supply board, perform the above test with the DMD display power disconnected. If the voltages return to nominal values, it's possible that your display is the culprit. Test the high voltages with a known good display to isolate the fault to either the HV Power Supply or the display panel.

Should your HV Power Supply fail, the circuit is almost identical to the circuit used by Williams in their WPC DMD Controller. Similar parts are required to rehab the Sega/Stern HV Power Supply.

As of April 2014, schematics for the HV Power Supply are no longer available on Stern's site.

====Typical Failures of High Voltage Power Supply====
[[File:Stern WS DMD PSU.JPG|right|thumb|300px|A Stern 520-5138-00 Dot Matrix High Voltage Power Supply]]

'''The nominal output voltages of this board are shown below.''' 
The voltages measured between game ground and each pin of CN2 (right side as installed in the game).
*-110V on CN2-1
*-98V on CN2-2
*+5V on CN2-6 (piped directly through from CN1-7. This was a method of minimizing connector complexity)
*+12V on CN2-7 -- 20V is supplied at CN1-6 and is regulated down to +12V by VR1, a 7812. Note: the voltage at this pin will be missing if the board isn't stuffed with the 7812. It is not known when Stern/Sega stopped stuffing this location.
*+68V on CN2-8

The fuse on the board is a 3/4 ASB fuse.

'''Common failures:'''

*Fuse blowing
*-110V missing or too low
*-98V missing or too low
*+68V missing or too low

'''Solutions:'''

A blown fuse is indicative of a failed rectifier diode at D1 or D2 (1N4004. Anything from a 1N4005 to a 1N4007 can be used too). When D1 fails, Q1 and Q3 often fail along with it. When D2 fails, Q2, Q4, and Q5 often fail along with it.

*-120V problems are often caused by a failed transistor at Q2 (MPS-A42) and/or Q4 (MJE15031). When one of the transistors fails, often the other one fails too. Replace zener diode D4 (3.9V, 1N4730), D6 (100V, 1N4764A) and D7 (13V, 1N4743A) as well.

*-100V problems are often caused by a failed transistor at Q5 (MJE15030) or zener diode D6 (100V, 1N4764A). It's best to replace both. The 2k/5W resistor on R8 might also be the problem source, mostly due to failed solder contacts.

*+60V problems are often caused by a failed transistor at Q3 (MJE15030) and/or Q1 (MPS-A92) When one of the transistors fails, often the other one fails too. Replace zener diode D3 (3.9V, 1N4730) and D5 (68V, 1N4760A) as well.

As of 2014, schematics for the display power supply board are no longer available on Stern's website.

The Data East display power section of the 520-5047-01 and 520-5047-02 boards is an almost 1:1 copy compared to the one on this board. 

==== Failed Dot Matrix Display ====

A failed Dot Matrix Display will obviously cause display problems. Once you've tested for proper voltages, swap in a known good display, and swap the suspect display into a known working game. If the suspect display doesn't work in the known working game, it's time for a new DMD display.

==== Corrosion Under Header Pins ====

[[File:DESegaSternDMDControllerCorrosion.jpg|300px|thumb|left|Corrosion under the dual row headers of a DMD Controller board]] 
Corrosion from leaky batteries, being the bane of pinball PCBs, finds it's way to many places that might not normally be suspected. Sometimes, alkaline corrosion invades the header pin carriers, as shown in the picture at left. In this case, enough of the signals between the MPU board and the DMD controller board were corrupted to prevent proper rendering on the DMD display. Cleanup via typical methods restored this board to proper operation.
 

==== Failed ribbon cable ====

The ribbon cables on Sega/Stern White Star games connecting the CPU to the display controller are particularly long and twisted. There is ample opportunity for the ribbon cable to be damaged.

You should reseat the ribbon at both ends several times to knock off accumulated corrosion. This might temporarily solve the issue.

A simple test of the ribbon cable integrity would be to reverse it, causing the conductors used within the ribbon to be "swapped". Remove the ribbon from both ends, and instead of seating it with the red stripe at pin 1, seat the ribbon with the red stripe at the opposite end from pin 1. Make sure you reverse both ends of the ribbon. If the results witnessed on the display are then different, there is a good chance you need a new ribbon cable.

Gently bending and twisting the ribbon cables may help uncover intermittent connections and a compromised cable. Don't bend/twist too vigorously as this in itself may compromise the cable.

==== Failed power connector on display driver board (CN2) ====
[[File:CN2.jpg|300px|thumb|left|The '''craptastic''' 3 pin DMD Controller power header at CN2.]] 
Sega/Stern (and even Data East) made a poor decision for the power connection to the display controller. CN2 is a .156, 3 pin connector, which connects 5VDC and Ground to the display controller. The connector can be installed upside-down and reverse the 5VDC and Ground connections. This may kill the ROM chip and other chips on the board.

The solder joints for these header pins fracture often, or the pins in the female housing lose their grip (and hence connection). It is good practice to repin both sides of this connection, using crimp-on TriFurcon pins in the female housing.
 

==== Blank Display After "Splash Screen" Or Unusual Messages (Failed 74HCT273 buffer IC on the MPU board) ====

[[File:BadSchematicTableIndex.jpg|300px|thumb|left|One manifestation of a failed U201 or an open between U201 and the plasma display connector. Image courtesy of Chris Hibler.]]
The 74HCT273 at U201 on the CPU board buffers the output to the display controller via the ribbon cable. Should this IC fail, incorrect or no data will reach the display controller. Most of the time, this results in only the "splash screen" appearing which is displayed by the DMD controller on it's own, or in rare instances, the odd displays shown at left. First an over-scaled "Location ID:" image is displayed then "Bad Schematic Table Index!". This particular failure was caused by a corroded trace between U201 pin 2 and the via just northwest of pin 2. However, the same message may be displayed any time that the data path between U201 and the DMD Controller fails (i.e. poor header connections, failed ribbon cable).

U201 can be tested with a DMM following the process described [[General#Testing_an_integrated_circuit| here]].
 

====Display Issues Caused by Mismatched Game and Display ROMs====
[[File:WhiteStarEffectF7.jpg|300px|thumb|left|This message appears when the display controller software can't correctly decode display "calls" made by the MPU. Note that hexadecimal numbers other than "F7" may be displayed. Image courtesy of Chris Hibler.]]
Over the course of a game's manufacturing run, and even post production, game and display software was updated. It is important to ensure that the game ROM version is compatible with the display ROM version. Newer versions of the game code may request a display routine from the display controller that the display controller can not make sense of. When this happens, the display controller will display "Effect NN", where "NN" is the hexadecimal number of the display routine received.

Note that a less likely failure of IC U17 (a 74LS245) on the display controller board, which buffers inputs from the MPU, can cause the same or similar behavior. Corrosion on the ribbon header pins (both ends) or a faulty ribbon cable are other possible reasons for this message.
 

===Sound problems===

Before going any further, check all of the basics in the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section. 

'''Basic operation (simplified) of the White Star CPU/Sound board audio part:'''
The main CPU (U200) makes sound calls to the sound CPU (U6) which instructs the BSMT to play a certain sound. The BSMT fetches the required data (sound sample) from the ROM memory (U17-U21-U36-U37) and feeds the 16-bits wide parallel data to a conversion circuit which makes it serial data (shift register, U23-U24). The serial data is fed into a DAC (U26, Digital to Analogue Converter) that outputs to a pre-amplifier (U30, OPAMP). The output from the pre-amplifier is fed into the TDA2030A amplifiers at U101/U102 and sometimes U100 (some boards have 3 amplifiers, one for each speaker) and from there the audio signal goes to the speakers.

[[File:XilinxCPLD.jpg | thumb | right | 300px| The XC9572XLT Complex Programmable Logic Device. The yellow paint spot indicates that it has been programmed.]] 
The White Star (modified) version of the MPU board replaces almost all of the prior version's sound circuitry with 3 surface mount ICs.
*Xilinx CPLD at U414 (XC9572XLTQFP, T indicating the 100-pin version, QFP indicating Quad Flat Pack)
*Atmel RISC processor at U402 (AT91R40008)
*Atmel flash memory at U8 (AT49BV162AT)

The Xilinx CPDL ([https://en.wikipedia.org/wiki/Complex_programmable_logic_device Complex Programmable Logic Device]) is programmed by Stern (or it's board manufacturer) via the [https://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] connector on the board.

The Atmel RISC processor ([https://en.wikipedia.org/wiki/Reduced_instruction_set_computing Reduced Instruction Set Computing]) replaces the 68B09EP of the prior board.

The Flash Memory contains the Sound Operating System. The correct version of the sound operating system my be "flashed" into the memory.
LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin #157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another). In April, 2016, "Chas" at Stern Pinball noted that sound operating system 8 (O/S 8) is backwards compatible with all WhiteStar (modified) games. It may even work with sound ROMs predating the WhiteStar (modified) board. However, there are known compatibility issues with early WhiteStar Sega games like StarShip Troopers.

The sound section of both board versions is quite reliable. The failure occuring most is a failed TDA2030A amplifier. If a sound problem can be isolated to one of the three fine pitch surface mount ICs on the WhiteStar (modified) board, the only option known as of April, 2016 is to return the board to Stern for repair. Stern does carry the parts necessary, but removal and replacement of such fine pitch parts is above the capability of most pinball hobbyists.

'''Sound missing from one of the speakers:'''
Possible failed TDA2030A amplifier.

'''No sound at all:'''
Check the voltages on the board. On the DC input connector CN2 there should be approx. +12V DC between pin 2 (ground) and pin 6 (+12V) and -12V between pin 2 (ground) and pin 3 (-12V), these voltages come from the Power Supply Board. On the board itself are two voltage regulators to convert the +12V and -12V to +5V and -5V for the pre-amplifiers, check these voltages by measuring between the ground (GND test point) and U30 pin 8 for +5V, U30 pin 4 for -5V.

Other causes of no sound at all are the U7 game ROM being corrupted or improperly seated. You can re-seat this ROM and it often solves the issue. If any of the voice ROMs (U17, U21, U36, U37) are corrupted or improperly seated, the sound will still work but will be corrupted or have intermittent issues such as scratchy sounds or improper sounds at specific times.

An incorrectly jumpered or installed RAM chip can also cause no sound. JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket).

Finally, if you have no sound at all, check that you have the correct sound board. Some operators may have swapped the Atmel based board with a BSMT2000 based board board for the older series White Star games. The Atmel based board will work in all White Star systems although some sounds may not be rendered correctly or at all. The BSMT2000 based board will work but will present no sound at all in all games newer than lord of the rings (2003).

'''Samples playing randomly'''
This happens on Whitestar (modified) CPU boards that emulate the BSMT2000 (which Stern could not source cheaply enough at the time). Reflashing the sound operating system firmware per Stern [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin 157] is recommended.

'''Sound is distorted'''
If the sound is distorted, a prime suspect is the TDA1543 (U26) chip. This sounds as if the volume is very over modulated and are “clipped”. Be sure to use the TDA1543 version and NOT the TDA1543A. The TDA1543A uses another protocol (Japanese). If the sound is distorted at master volume levels below 4, see the [http://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#Loud_Hum_and_.2F_or_Distortion_at_Low_Sound_Levels "Loud Hum and/or Distortion at Low Sound Levels"] section below.

'''Sound cuts out at the exact same point in a clip every time'''
If the sound consistently cuts out, or volume is lowered, or the clip is muffled, every time at the same point in the clip, there is a possibility that the 6116 RAM at U4 has failed.

'''Sound volume is extremely loud'''
Possible TDA1543 (U26) chip failure or counterfeit chip.

'''Loud hum'''
If there is a loud hum coming out of the speakers as soon as the game is turned on, make certain that the +12V is present.

'''Loud hum/burnt speakers/12V DC coming out of the speaker connector'''
If you have a machine with all speakers dead, check for voltage on the speaker wires. If the -12V wire from the driver board to the CPU board is disconnected, it can cause 12V DC to be sent down the speaker line, causing a loud hum and fairly quickly destroying any speakers connected!
 

'''Music Sounds Like Alvin and the Chipmunks'''
[[File:WhiteStarW6JumperLocation.jpg|left|thumb|300px|Schematic diagram showing the physical location of jumper W6 between the sound section 68B09E and the BMST2000, enabling the use of 8Mb EPROMs]] 
The original WhiteStar schematics mention jumper W6, which "must be installed for games that use 8Mb Sound EPROMs (U17 U21 U36 U37). For games which use 4Mb Sound EPROMs this jumper is not installed but 4Mb EPROMS will work on boards with W6 installed". This boils down to...install jumper W6. The manifestation of using 8Mb ROM images on a board with W6 not installed is sound that appears to be "Alvin and the Chipmunks"-like.

[[File:YT.png]] A YouTube video showing an incorrectly jumpered WhiteStar MPU with Harley Davidson ROMs can be found [https://youtu.be/7MXxngST5g4 here].

Note that the WhiteStar (modified) MPU board does not provide jumper W6, nor is it needed. The WhiteStar modified board works with both 4Mb and 8Mb sound ROMs, as if W6 was installed.
 

====Sound Section Jumper Settings====
JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket). An incorrectly jumpered or installed RAM chip can result in no sound at all.

'''Important:''' Under normal operation...
*JMP2 should be on the right pair of pins
*JMP3 should be on the top pair of pins, and
*JMP4 should be on the bottom pair of pins.

Placing the jumpers in any other position will cause sound to be missing. These jumpers are provided to update the sound operating system within the flash memory at U8.
 

====Loud Hum and/or Distortion at Low Sound Levels====
[[File:SternServiceModForLowSoundLevels.jpg|300px|thumb|left|Trim POTs connected across R106 and R110. This mod was offered by an aftermarket seller. Image courtesy of Jack Jarrett]]
[[File:WhiteStarResistorHack.jpg|300px|thumb|right|Trim POTs connected across R106 and R110 in a rather kludgy way...but it works. Image courtesy of PinSider Capt_Pinball]] 

Stern released [http://www.sternpinball.com/upload/downloads/sb133.pdf Service Bulletin 133], which discusses a fix for a loud hum and / or distortion when the master volume is set below level 4. The machines that are specifically effected are Monopoly and Austin Powers. However, it has been over 10 years since these games have been released, and boards get transplanted to other games over time. So, it is important to check the two resistors (R106 and R110) in the amplification section of the CPU / sound board to see if the correct values are installed, regardless of the game. The correct resistor values should be 33K ohms 1/4 watt for R110 (ORG-ORG-ORG-GOLD), and 10K ohms 1/4 watt for R106 (BRN-BLK-ORG-GOLD). Consult the service bulletin for more details, and the layout of the amp section. The R106 and R110 control the analog volume. When these resistors are broken (open) the analog volume goes to 100% and can't be controlled via the buttons (digital volume) on the coin door. The higher the resistor value the higher the volume.

Another method of accomplishing the same thing, without removing and replacing a resistor, is to add a resistor to the back of the board, across R106 and R110, creating the equivalent resistance as mentioned above. A 4.7K resistor seems to be a sweet spot.

Yet another method used is to clip a 10K trim pot across each resistor as shown in these images. The trim pot can be adjusted to a good compromise between hum and volume.
 

==== Low Background Sound Volume ====
[[File:WhiteStarBackgroundSoundVolume.jpg|300px|left|thumb|Background sound level setting on Roller Coaster Tycoon]] 
Some games, at least Viper Night Drivin' and Roller Coaster Tycoon, provide a means of adjusting the level of the background sound. The sound can be adjusted from level 1 (loudest) to level 15 (lowest).
 

====Adding a Second Backbox Speaker to some Sega Games ====
[[File:NewSpeakerAndSpeakerBlank.jpg|300px|left|thumb|Adding a second backbox speaker may improve the sound in games shipped with a single backbox speaker. Buy the speakers in pairs. This image shows the new speaker installed onto the left speaker bracket, and the right speaker position "blank" from a StarShip Troopers game. The "blank" must be modified so that the new speaker can be attached.]] 
A chap named Martin Riley submitted a nice article to the PinballNews explaining how to add a second backbox speaker to games like StarShip Troopers.

From the article... 
"Mid-life Sega games from Twister through to and including Viper Night Drivin' only had the left hand backbox speaker plus the cabinet speaker and only two of the 3 audio amps are populated on the CPU board.

Late Sega games from Lost in Space onwards have two backbox speakers but they are effectively mono as they are both connected to the left channel audio amp on the CPU board (the right channel amp being unpopulated)."

The complete article can be found at http://www.pinballnews.com/learn/speaker/index.html

The article lists all components required to add the 3rd speaker channel. Some (maybe all) two channel boards are not stuffed with C122, which is not listed in article parts list. You'll need one more 0.1µF axial ceramic capacitor for C122.

Adding a 3rd speaker to StarShip Troopers improved the sound quite a bit. The sound is richer and cleaner. The emphasis on some sounds is more pronounced and easier to hear. Edit: months later, I was testing a board in my StarShip Troopers that didn't have the 3rd amp. Forgetting that I had added the 3rd amp to my MPU, I initially thought something was wrong with the sound that the MPU under test was producing. It was merely the difference between a single and dual backbox speakers.

Mounting the additional speaker to the "blank plate" (as found in StarShip Troopers) required drilling the rivets that attach the speaker grill, and replacing them with low profile head screws. This is only necessary for Sega "Showcase" backbox games. For games like Independence Day, mounting the additional speaker should be trivial.

 

==== Is a Second Backbox Speaker Really Worth It? ====
While some have reported good results adding a third amp and second backbox speaker to these early Sega games, there are questions about the efficacy of such a solution. While better speakers themselves will improve the sound, the game-specific sound samples in the ROMs are mastered as mono sound clips. There are very few sounds in the game that are true stereo sound and these are usually simple sound effects which were used in multiple games. 

You can listen to and judge for yourself by running the Bridge front end and the M1 MAME music player. Bridge and links to the M1 player can be found [http://www.e2j.net/downloads.html here]. 

The mono mastering continued through the White Star II and SAM systems. As David Thiel, who has created music and sound for numerous Data East and Stern pinball machines, states on this [http://daudioguy.multiply.com/video/item/5/Family_Guy_Stern_Pinball_Music_and_Sound_Effects_by_David_Thiel?&show_interstitial=1&u=%2Fvideo%2Fitem page] of his website, he "composed, arranged, performed, mixed and mastered (all the music for Family Guy) for 24 kHz 16 bit Mono." 

===Flipper problems===
====Non-Functioning Flippers====
====Weak Flippers====
=====Progressively Weak Flippers=====

==Game Specific Problems and Fixes==
'''Lord Of The Rings''' 

If your Balrog stops registering hits, a little checking will sort it out. The mini microswitch with a roller arm used to register hits may need adjusting. Known past problems are a flaky or bad switch, and/or wiring. The Balrog moves in such a way that wires can break inside where you can't readily see them. It's easy to check the switch and wires with a meter. The wires push into an IDC connector nearby; be sure they are pushed in tight.

There isn't any adjustment for the micro switch, except for bending the blade with the mini-roller; try bending the blade outwards slightly. According to the manual, sw #28 stays normally closed and then a Balrog hit opens the switch. This is not the normal target arrangement. So using the Balrog test mode in diagnostics, the switch should stay solidly closed, and then only open when Balrog is tilted forward.

'''The Shire and Gimli VUK switches.''' 
These get hammered on LOTR and will eventually need replacing, There isn't any easy solution other than replacing the flaky switch. The tiny black screws on the Stern switches are 3/16". You will need a nut driver that size if you want to attempt replacement of the switches.

The Shire (and Gimli) VUK switch, are fork blade microswitches. Stern part number 180-5116-01. 
Spec on side of switch says Cherry .1A 125v E63. Try parts4pinballs.com or your favorite Stern parts supplier.

The Shire VUK. 
It's easiest to remove the entire Bottom Left VUK coil and bracket from under the PF (playfield) to change the fork switch. 
Take out the two largest bolts first, using a cross-head (phillips) screwdriver on the top and 11/32" nut runner (or socket) on the bottom. 
Remove the metal VUK arch from the top of the playfield. 
Remove the two lower wood screws (1/4" drive) leaving the one on the corner near the T-nut. 
Supporting the Coil Bracket, remove the last 1/4" screw. 
Unclip the connector from the coil and VUK. Remove coil and bracket assembly. 

Microswitch small screws are 3/16". As stated before, to remove the switch correctly you need a nut driver (or socket) that size.
You should be able to slide the heatshrink tubing all the way up the wires, solder on the new switch and then slide them back down in place. If not, use new heatshrink tubing. Assembly is above steps in reverse. Test in switch tests before replacing assembly and then by throwing a ball in the Shire in attract mode one the assembly has been correctly replaced.
 

'''Ripley's Believe it or Not! and The Simpsons Pinball Party''' 
Not certain what code versions apply with this. When the coin door is open, and the first ball drains, the game will not recognize that the ball has drained at all. Likewise, it will not kick the next ball over to the shooter lane. This is even with the solenoid voltage interlock switch pulled out. It is presumed that the memory lock switch has to be closed for the game to function properly.

This may apply to more games of this vintage other than just these two!
 

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.

*'''Striker Xtreme:'''
**Problem: '''Display is blacked out or only coming on for a few seconds before blanking out.'''
**Cause: Resistors R6 and/or R7 on the display power supply board have gone bad (open or increased in value).
**Solution: Replace resistors R6 AND R7 on the display power supply board. Both are 330k @ 1/2 watt
*'''Simpsons Pinball Party:'''
**Problem: '''When last ball drains, game still thinks its in play.''' Ball search or power cycle will eventually find it.
**Cause: Cracked solder joint on trough board.
**Solution: Pull both trough boards. A 1/4" wrench can be useful in getting the back board off. In this case, the obviously cracked solder connection was on the receiver board in front. But while the board is out, the optos were cleaned with Windex.
**This can be verified by waiting for the problem to show up, then go into switch test. Previously, switch #5 (leftmost) had been suspected and had been re-aligned, but that was probably not necessary.
*'''Starship Troopers, but applies to all:'''
**Problem: '''No display, no sound, upper amplifier went up in smoke.'''
**Cause: Connector CN4 on MPU / Sound board and CN1 of display power supply board were swapped. Both CN4 and CN1 are keyed the same. In haste, these connectors can be mixed up. Keep in mind that the speaker output is a very light gauge wire versus the heavier gauge for the display power supply input.
**Solution: This was not as bad as expected. After studying the schematics, only +20V (CN1 pin 6 - pin 4 is GND on both connections) can potentially backfeed through the sound circuitry. Amplifier U101 failing spectacularly possibly prevented additional damage. Amps U101 and U102 were replaced (U100 was not stuffed on this board). After replacing the amps, sound came back, but was very faint. Further investigation revealed 3 100Kohm resistors had failed, R21, R22, and R24. Also, U26, the TDA1543 DAC, had also failed.
*'''Goldeneye, but applies to all:'''
**Problem: '''Blanking signal OK but driver board blanking LED keeps blinking.'''
**Cause: Ribbon cable from MPU to driver board faulty.
**Solution: Replace ribbon cable.
*'''Goldeneye, probably Twister:'''
**Problem: '''Magnets don't work, MAG2 LED on magnet board keeps blinking in test mode.'''
**Cause: Bad connection from magnet board to magnet between flippers.
**Solution: Fix connection.

User talk:Jimpal

2023-03-22T12:24:54Z

Jimpal:

dr. Dude was one of the last 11C. Wonder why they still used switches on this one. When I open my Rollergames next time I will check if it's the same with this one.

I can't recall seeing double switches on the pops, but I know that I had to change out a zener on one of the spec. sol. trigger lines. I can't comment about the slings, as I did not have work on them. This was on a call back in Nov., so things are a tad hazy, but I do remember the shorted zener. Not certain until more data is collected, but it seems like there may be some inconsistencies here. One game did this, while the other did this. That wouldn't be a first for WMS though. - Jim

From Force: Barakandl identified several inconsistencies and mistakes in the existing chart. I simply posted the new chart for him since he was unfamiliar with wiki table syntax

== system 80 transformer grounds ==

I had two Gottlieb The Games at one point, and both used quick disconnect connections on the transformer panel, rather than direct solder connections.

Example: http://www.ipdb.org/showpic.pl?id=3391&picno=28681

--[[User:ForceFlow|ForceFlow]] ([[User talk:ForceFlow|talk]]) 12:45, 26 September 2016 (CDT)

----
Quick disconnect as in the female spade connectors in the pic you referenced, or quick disconnect as in an inline Molex plug (9-12 pin roughly) in addition to the female spade connectors in the pic?--[[User:Jimpal|Jimpal]] ([[User talk:Jimpal|talk]]) 06:21, 27 September 2016 (CDT)

---
I was referring to the spade connectors, but there were also inline molex plugs. --[[User:ForceFlow|ForceFlow]] ([[User talk:ForceFlow|talk]]) 11:31, 27 September 2016 (CDT)

----
Thanks for the info. This made me research other games from that era. --[[User:Jimpal|Jimpal]] ([[User talk:Jimpal|talk]]) 06:41, 28 September 2016 (CDT)

Williams System 3 - 7

2023-03-22T12:21:13Z

Jimpal: Undo revision 23413 by Jimpal (talk)

Click to go back to the [[Williams_Repair_Guides | Williams solid state repair guides index]].

=Introduction=
Williams entered the [http://www.pinwiki.com/index.php?title=Glossary#Solid_State_.28SS.29 SS] or Solid State era with a conversion of a 1976 Williams [http://www.pinwiki.com/index.php?title=Glossary#Electro_Mechanical_.28EM.29 EM] or Electro Mechanical pinball game called [http://www.ipdb.org/machine.cgi?id=4828 Grand Prix].

'''System 1''' is considered to be the Solid State version of ''Grand Prix''. It is thought that about 5 Grand Prix EM games were converted to SS prototypes using the new System 1 MPU Board and digital displays. The computer was only used for accumulating and displaying the player scores.

IPDB links: [http://www.ipdb.org/machine.cgi?id=5647 Grand Prix SS version]          [http://www.ipdb.org/machine.cgi?id=1072 Grand Prix EM version ]

'''System 2''' was next, with a 10 unit run of another 1976 EM game called ''Aztec''. A working SS version is very rare. Both System 1 & 2 occurred quickly after each other at the end of 1976. Aztec SS was still a hybrid machine retaining the EM chime unit in the cabinet and a credit window with an EM numbered reel behind the backglass). Player scoring was still the only digital function at that time.

IPDB links: [http://www.ipdb.org/machine.cgi?id=4828 Aztec SS version]          [http://www.ipdb.org/machine.cgi?id=119 Aztec EM version ]

'''System 3''' games were the first Williams SS production games, starting with ''[[Hot Tip]]'' in Nov. '77 and ending with ''[[Disco Fever]]'' in Aug '78. There were based on the Motorola 6800 8-bit CPU and using a Motorola 6820 PIA (Peripheral Interface Adapter) to handle the Display I/O from the MPU board. They also had three other 6820 PIAs on the Driver Board reading targets and other switches as inputs and controlling the insert Lamps and solenoids as outputs. Solenoid drives were mainly used for ball handling by firing coils, with a few triggering sound calls or a 'start of game' tune. This was the start of Williams using computers for game rules and settings. At this point they designed an 8x8 Switch Matrix, an 8x8 Lamp Matrix and solenoids driven by Darlington transistors. This design remained virtually unchanged to the end of Williams System 7.

During System 3 (''[[Phoenix]]'' and ''[[Disco Fever]]'') a memory protect circuit modification was added as to help protect CMOS RAM data during power up and power down of the game. DIP switches were used to program game settings (such as # of balls per game, high score replays).

'''System 4''' games ran from ''[[Pokerino]]'' in Nov '78 through to ''[[Stellar Wars]]'' in Mar '79, according to IPDB.com. A notable game which outsold all of the other System 4 games combined with a production run of 19,505 was ''[[Flash]]'' (Steve Ritchie's first designed game for Williams). During System 4, Williams moved from using DIP switches to change game settings to having the game settings changed from the coin door switches. The settings were still stored in battery protected CMOS RAM. [ed Note: Citation needed] A coin door interlock switch enforced that CMOS memory could not be modified unless the coin door had been opened by the operator. Some of the game audits (coins accepted, total number of games played, etc.) still could not be changed without access to the MPU board behind the backglass.

'''System 6''' games ran from ''[[Tri Zone]]'' in Jul '79 to ''[[Scorpion]]'' in Jul '80. Two notable games from this era were from the end of '79 and the beginning of '80 ''[[Gorgar]]'' and ''[[Firepower]]''. Gorgar (14,000 produced) was the first talking pinball, and Firepower (17,410 produced) both talked and introduced the 'Lane Change' and 'Multiball (tm)' features to SS games. Note that there had been Multiball play available in EM games, it just wasn't called Multiball (tm) until Firepower. and this is a common misunderstanding. The features these games introduced became standards for almost all pinball games produced right up until today.

'''System 6a''' deserves to be mentioned here as it marked a transition to System 7. The game ''[[Alien Poker]]'' from Oct '80 used the Syatem 6a MPU board (which was not very different from System 6). But it supported 7 digit scoring displays and a redesigned Master Display Driver board, located behind the backglass on the back of the 'Lamp Board'. It also used a special 4 digit "credit/match" display in the approximate position where the System 6 Master Display Driver had been showing the same information (on a 6 digit display, with 2 of the digits unused). This new 7 digit scoring displays with a 4 digit credit/match display were then used in all the System 7 games (and System 9).

'''System 7''' games ran from ''[[Black Knight]]'' in Nov '80 through to ''[[Star Light]]'' in Jun '84.

IPDB link: [http://www.ipdb.org/search.pl?mpu=4&qh=checked&ng=checked&sortby=date&searchtype=advanced Complete System 7 Game list]

''Black Knight'' (13,075 produced) introduced a two level playing field and Magna-Save (tm) where the ball could be stopped from draining down the sides by pressing a cabinet button that activated an electromagnet. ''Star Light'' (100 produced) was a 'boutique' game by Williams' production standards as the focus was on ramping up production for the first System 9 game Space Shuttle (7,000 units). At least one Star Light game was made as the Prototype for System 9.

Note: Further discussion of changes and good pictures of the backbox boards for System 3-7 games can be found here:
[http://tuukan.fliput.net/wms_en.html Tukkan.fliput.net]

=Games=
==System 3==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Hot Tip]]|| 11-1977 || 477 || Chimes || ||
|-
|[[Lucky Seven]]|| 03-1978 || 480 || Chimes || ||
|-
|[[World Cup]]|| 05-1978 || 481 || Type 1 Sound || ||
|-
|[[Contact]]|| 05-1978 || 482 || Type 1 Sound || ||Widebody
|-
|[[Disco Fever]]|| 08-1978 || 483 || Type 1 Sound || ||Used banana flippers
|}

==System 4==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Pokerino]]|| 10-1978 || 488 || Type 1 Sound || ||Widebody
|-
|[[Phoenix]]|| 11-1978 || 485 || Type 1 Sound || ||
|-
|[[Flash]]|| 01-1979 || 486 || Type 1 Sound || ||First game with continuous Background sound/Later games produced on System 6 platform
|-
|[[Stellar Wars]]|| 03-1979 || 490 || Type 1 Sound || ||Widebody/Later games produced on System 6 platform
|}

==System 6==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Tri Zone]]|| 07-1979 || 487 || Type 1 Sound || ||
|-
|[[Time Warp]]|| 09-1979 || 489 || Type 1 Sound || || Used banana flippers for most of run.
|-
|[[Gorgar]]|| 12-1979 || 496 || Type 2 Sound w/ Speech || ||First game with speech
|-
|[[Laser Ball]]|| 12-1979 || 493 || Type 1 Sound || || Widebody
|-
|[[Firepower]]|| 02-1980 || 497 || Type 2 Sound w/ Speech || ||First SS Multiball (3 balls). First lane change.
|-
|[[Blackout]]|| 06-1980 || 495 || Type 2 Sound w/ Speech || || First Williams game where a relay was used to turn general illumination on / off for effect.
|-
|[[Scorpion]]|| 07-1980 || 494 || Type 1 Sound || ||Widebody
|}

==System 6A==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Algar]]|| 09-1980 || 499 || Type 1 Sound || 7 digit display board||Widebody
|-
|[[Alien Poker]]|| 10-1980 || 501 || Type 2 Sound w/ Speech || 7 digit display board||
|}

==System 7==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Black Knight]]|| 11-1980 || 500 || Type 2 Sound w/ Speech || ||First game with magnasave
|-
|[[Jungle Lord]]|| 02-1981 || 503 || Type 2 Sound w/ Speech || ||
|-
|[[Pharaoh]]|| 05-1981 || 504 || Type 2 Sound w/ Speech || ||
|-
|[[Solar Fire]]|| 07-1981 || 507 || Type 2 Sound || ||
|-
|[[Barracora]]|| 09-1981 || 510 || Type 2 Sound || ||
|-
|[[Hyperball]]|| 12-1981 || 509 || Type 2 Sound ||Uses different driver board than pinball games ||Not a pinball - a flipperless game firing tiny pinballs
|-
|[[Cosmic Gunfight]]|| 06-1982 || 502 || Type 2 Sound || ||
|-
|[[Varkon]]|| 09-1982 || 512 || Type 2 Sound || || Pinball in stand-up Video cabinet
|-
|[[Warlok]]|| 10-1982 || 516 || Type 2 Sound || ||
|-
|[[Defender]]|| 12-1982 || 517 || Type 2 Sound || ||
|-
|[[Time Fantasy]]|| 03-1983 || 515 || Type 2 Sound || ||
|-
|[[Joust]]|| 04-1983 || 519 || Type 2 Sound || ||Two player head-to-head pinball
|-
|[[Firepower II]]|| 08-1983 || 521 || Type 2 Sound || Uses 50v Flipper Power Supply Board ||
|-
|[[Laser Cue]]|| 02-1984 || 520 || Type 2 Sound || ||
|-
|[[Star Light]]|| 06-1984 || 530 || Type 2 Sound || ||
|}

Game date of release and model numbers provided by the Internet Pinball Database - http://www.ipdb.org

=Documentation=
==Manuals & Schematics==
Most manuals and ROM files can be found on IPDB.org for each specific game.

* [[media:01-backbox-sys6.pdf|System 6 Backbox Wiring Diagram]]

==Parts Catalogs==
Parts catalogs can also be useful, which include part numbers (helpful for purchasing parts online), exploded views of assemblies (helpful to see how the assemblies are put together), and board layouts & parts lists, and diagrams for controlled lamp, solenoid, and rubber locations.

Online copies of Bally & Williams parts catalogs can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball].

{| class="wikitable"
|-
!Manufacturer
!Catalog
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|1980 Parts Catalog
|
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/ltjq/#p=1 Viewer]
|Hot Tip, Lucky Seven, World Cup, Contact, Disco Fever, Phoenix, Flash, Tri-Zone, Pokerino, Time Warp, Stellar Wars, Laser Ball, Scorpion, Blackout, Gorgar, Firepower, Algar, Black Knight, Alien Poker, Cosmic Gunfight, Jungle Lord, Pharoah, Solar Fire, Hyperball, Barracora
|This catalog covers all system 3-6 games, and the first third of the system 7 games.

|}

==Service Bulletins==
Most service bulletins can be found on IPDB.org for each specific game.

==Instruction Cards==
* [http://www.pinballrebel.com/pinball/cards/ Instruction Cards & Labels]

==Fuses==
===Power Supply===

{| class="wikitable" style="text-align: center;"
|+Williams System 3 - 7 Power Supply Fuse Ratings
|-
!System
!F1
!F2
!F3
!F4*
!F5
!F6
!F7
|-
|3 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 15amp FB || 4amp SB || NA || NA
|-
|4 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 4amp FB || NA || NA
|-
|6 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 4amp FB || NA || NA
|-
|7 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 7amp SB || 7amp SB || NA
|}

Note: The value of F4 does vary. Check the game manual for the correct rating. It's usually 10A for games with 2 flippers. Later System 7 games with a separate flipper power supply do not use F4. 

==ROM Files==
Most manuals and ROM files can be found on IPDB.org for each specific game.

* [http://www.planetarypinball.com/mm5/Williams/tech/roms.html ROM Files]

Note: The ROMs hosted on Planetary Pinball for World Cup has an issue. World Cup requires a [[#White_Flipper_ROM_Exceptions|special white flipper ROM specific to World Cup]], which [http://www.ipdb.org/machine.cgi?id=2810 can be found on IPDB].

===Combining System 3-6 Original ROMs Into a Single ROM at IC14===
[[File:WMSSystem6ROMConfig.jpg | thumb | left| 300px| A System 6 TriZone MPU, featuring combined ROM images at U14.]] 
For all System 3-6 games, the ROMs that might be located at U26, U22, and U21 (left to right on the top ROM row) can be replaced with a single 2716 2kb ROM (or EPROM) at IC14 that contains the combined images. When doing so, jumper J3 should be IN, jumper J4 OUT. These jumpers are located just above the ROMs and to the right of IC15. 

===Diagnostic ROMs by Pincoder===
Free Diagnostic ROM images for Williams System 3-7 games can be found here:
* [https://pincoder.ca/ Pincoder Website]
They require the use of EPROM chips and a chip programmer. However, you can choose to skip sourcing EPROMs and the chip programmer by using the available [https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/ Pincoder Adapter] right out of the box. Simply plug it into the MPU board, select a test, and power on the game. Full documentation can be downloaded from the Pincoder website. The ROM images and the adapter are actively supported.

===Flipper ROMs===
The OS (Operating System) for a Williams pinball game is called the Flipper ROM. Flipper ROMs with the same color label can be considered generic, although there is at least one exception where a 'custom' White Flipper ROM was used "World Cup".

The Game ROM can be considered the 'personality' ROM, it provides the rules and objectives that are specific to that game's playfield layout. It also maps the Lamps, Solenoid and Switch Matrix to their specific purpose for that game and controls how they are sequenced and timed. Examples would be the 'attract mode' lamp sequence or when sound / speech select calls are made.

Because of large game production runs, Williams bought batches of Masked ROMs (fixed and not erasable) for the games. This was cheaper at the time than using Eproms (UV erasable, with a small window) as Eproms were still fairly expensive in the 80's. They used the same method for producing most of their Flipper, Game and Sound ROMs.

It is sometimes a good idea to replace old masked ROMs with EPROMs, since the original masked ROMs are 30+ years old and as the legs blacken and tarnish, they will weaken and fall off. For a similar reason, many of the ROM sockets on the MPU boards will need to be replaced, especially any sockets bearing the words 'Scanbe', which are poor quality. Masked ROMs are very stable as they start life as all 1's and then the information is programmed by "burning" each selected bit open, like blowing a tiny fuse. This process is not reversible, and ROMs will rarely lose their programming over time, unless the remaining whisker-like "fuses" start to fail. The practice and term to "burn" ROMs carried over to other storage media, such as CDs and EPROMs, even though different technologies and processes were used to store the data.

====Flipper ROM Colors====
Williams used standard ROM files for System 3-7. These two Flipper ROMs are located at IC17 and IC20. Systems 3-6 use two 2716 or 2316 Eproms, while system 7 used a 2716 in IC20 and a 2532 in IC17 (a 2732 can be used at position IC17 after modifications are made to the board).

=====White Flipper ROMs=====
White flipper ROMs were used in all System 3 games and two System 4 games...
*Hot Tip
*Lucky 7
*World Cup
*Contact
*Disco Fever
*Pokerino (system 4)
*Phoenix (system 4)

=====White Flipper ROM Exceptions=====
World Cup uses White Flipper ROMs, but the ROM in IC17 is unique. The MPU will not boot and run with the standard White flipper ROM. However, the World Cup White flipper ROM can be used in all other White Flipper ROM games.

=====White Flipper ROM Issues=====
When downloading ROM software for World Cup, be aware the code available directly from Planetary Pinball has known faults and will not work properly. Code available from IPDB generally is correct and functional. The issues with these games is as follows:

World Cup: Provided with the standard IC17 Flipper Rom, not the unique one required for World Cup.

Lucky 7: When the original 512 byte files were combined into a 2k file for IC14 Game Rom, blank areas were entered incorrectly.
This causes the machine to register a failed checksum test when attempting to enter settings via the dip switches. (Note: The copy on Planetary Pinball appears to have been corrected).

Hot Tip: When the original 512 byte files were combined into a 2k file for IC14, they were done out of order. (Note: The copy on Planetary Pinball appears to have been corrected).

====Yellow Flipper ROMs====
The yellow flipper ROMs were used in 2 games...
*Stellar Wars
*Flash (later production of Flash used Green flipper ROMs, which are preferred. The game ROM version must match the flipper ROM color)

====Green Flipper ROMs====

The green flipper ROMs were used in System 6 and 6A games from Tri Zone (Jul '79) to Alien Poker (Oct '80)...
*Tri Zone
*Time Warp
*Gorgar
*Laser Ball
*FirePower
*Blackout
*Scorpion
*Algar
*Alien Poker

=====Green Flipper ROM Exceptions=====

Ted Estes developed a "divide by 10" ROM that allows /10 scoring for all 6 digit Green flipper ROM games with the exception of Algar and Alien Poker. These 2 games utilize an extension to the operating system ROM contained wholly in the game ROM which is incompatible with the Ted Estes hack (when enabled - with the hack disabled, the game works fine). Installing the hacked ROMs in these games isn't recommended since there may be other side effects.

The Alien Poker and Algar operating system extensions shift internal scoring before and after the normal routines. i.e. Internally, Alien Poker and Algar are 6 digit games.

====Blue Flipper ROMs====
The blue fipper ROMs were used in all System 7 games, Black Knight (Dec '80) and later...
*Black Knight
*Jungle Lord
*Pharoah
*Black Knight Limited Addition
*Solar Fire
*Barracora
*Hyperball
*Thunderball
*Cosmic Gunfight
*Varkon
*Warlock
*Defender
*Rat Race
*Time Fantasy
*Joust
*FirePower II
*Laser Cue
*Star Light

=====Blue Flipper ROM Exceptions=====
Star Light (June '84, 100 produced) which was the last System 7 game, appears to have non-standard Blue Flipper ROMs. For small production runs, games were supplied from the factory with EPROMs.

==Circuit Board Schematics and Assembly Drawings==
===Connectors===
* [[Media: Molex-Connectors-Firepower-1.1.pdf|System 3-7 Molex Connectors]]

===Displays===
* [[media:08-masterdisplayboard-sys3-6.pdf|Display Diver Board Assembly Drawing]]
* [[media:09-masterdisplaylogic-sys3-6.pdf|Display Driver Board Logic Diagram]]

===Driver Board===
[[File:System3-7DriverBoardLayout.jpg|300px|thumb|left|Williams System 3-7 driver board layout]] 
* [[media:05-driverlogic-sys3-6.pdf|System 3-7 Driver Board Logic Diagram]]
* [[media:04-driverboard-sys3-6.pdf|System 3-6 Driver Board Assembly Drawing]] (Note: The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)
* [[Media:wms-sys3-6_driver-board_layout.pdf|System 3-6 Driver Board Layout]]
* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf|System 3-6 Driver Board Schematics (1 of 2)]]
* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf|System 3-6 Driver Board Schematics (2 of 2)]]
 

===MPU===
[[File:WilliamsSystem3MPURevisionA.jpg ‎|left|thumb|300px|System 3 MPU IC Locator]] 
System 3 MPU IC Identification Map. 
The System 4 MPU adds only IC26 on the left side of the board, just above IC22 where the odd looking solder pads are.
 
* [[media:wms-sys3-mpu-layout.jpg|System 3 MPU Board Layout]]
* [[media:wms-sys3-mpu-schematic.jpg|System 3 MPU Board Schematic]]
 
* [[media:Williams_System-4_MPU_Layout.jpg|System 4 MPU Board Layout]]
* [[media:Williams_System-4_MPU_Schematic.jpg|System 4 MPU Board Schematic]]
 
* [[media:03-cpulogic-sys6.pdf|System 6 MPU Board Logic Diagram]] (Note: Because IC9 and IC10 can be bypassed directly, this diagram is accurate for System 6a)
* [[media:02-cpuboard-sys6.pdf |System 6 MPU Board Assembly Drawing]] (Note: Because IC9 and IC10 can be bypassed directly, this diagram is accurate for System 6a)
* [[Media:wms-sys6_mpu_layout.pdf|System 6 MPU Board Layout]]
* [[Media:wms-sys6_mpu_schematics.pdf|System 6 MPU Board Schematics]]
* [[Media:wms-sys6_mpu_bom.pdf|System 6 MPU Board Bill of Materials]]
 
* [[Media:wms-sys7_mpu_schematics.pdf|System 7 MPU Board Schematics]]

===Power Supply===
* [[media:wms-sys3-6_power_supply_early_layout.jpg|Early System 3-6 Power Supply Board Layout]]
* [[media:wms-sys3-6_power_supply_early_schematics.jpg|Early System 3-6 Power Supply Board Schematics]]
* [[Media:Wms-sys3-6-powersupply-assembly.pdf|System 3-6 Power Supply Board Assembly Drawing]]
* [[Media:wms-sys6_power-supply_layout.pdf|System 3-6 Power Supply Board Layout]]
* [[Media:wms-sys6_power-supply_schematics.pdf|System 3-6 Power Supply Board Schematics]]

===Sound Board===

During the long run of System 3 through 7 games, Williams used two basic board types, designated Type 1 and Type 2.

====Type 1 Sound Board====

[[Media:WMS_Sys3-6_Type_1_Sound Board.pdf|System 3-4 Type 1 Sound Board Assembly Drawing and Schematic]]

====Type 2 Sound Board====

The [[Media:Wms-sys6-7-soundspeech-assembly.pdf|System 6-7 Sound & Speech Boards Assembly Drawing]], crafted by Phil Butcher is a great debugging resource.

==Other Documentation==
* [http://www.firepowerpinball.com/ Documentation for Firepower]

==Errors==
===Power Supply===
* Note that the parts bill of materials for some (perhaps all) system 7 games call out a 2N6087 power transistor for Q5. This is most likely a typo. A 2N6057 or 2N6059 should be used.

=Technical Info=

==Proprietary Numbers on Chips==
Some Bally IC chips are marked with proprietary Williams part numbers, and no other markings are present. Below is a list of some of the most common chips found on Williams boards, and the more commonly referred to chip.
*5A-8987 - 6800 CPU chip, Motorola part #SC44216P.
*5A-9150 - 6808 CPU chip
*5A-8972 - 6820/21 PIA chip, Motorola part #SC44067P.
*5A-9903 - 6810 RAM chip

==Backbox Overview==
The Williams backbox is similar for most of the games in the System 3-7 games. System 3-6 remained fairly similar in their backbox layouts. System 7 introduced a number of changes.

* During the beginning of System 7 the transformer moved from the backbox to the lower cabinet.
* The System 7 PSU was redesigned and changed to incorporate a G.I. relay,
* An upgraded System 7 MPU Board was used, which featured a built-in numeric diagnostic display.

The first two System 3 games ([[Hot Tip]] & [[Lucky Seven]]) used chimes and had no sound boards in the cabinet backbox. In the remaining System 3 games and all System 4 games, the sound board was located in the body cabinet, rather than the backbox.

Sample games of the first System 6 game, [[Tri Zone]] had the sound board located in the lower cabinet, but it was moved into the backbox for production games and all other System 6 & 6A games.

For the System 6A game [[Alien Poker]] and all System 7 games, an add-on board sppech board was introduced, which contained additional ROMs for speech.

==MPU Boards==

===System 3===
[[File:WMS sys3 MPU board.JPG|thumb|left|300px|Williams System 3 MPU Board]] 
System 3 was a major step by Williams to digital pinball games. It ushered in the Solid State machines, but to begin with there were problems with acceptance of the new machines.

Williams had the Driver board firing the solenoids on Chime units on the first two System 3 games, and even had a device called a 'noisemaker' (an EM score reel mounted in the body of the game) to provide the sounds of the score reels clicking over! This gave the player the familiar sounds of EM machines which were still around, The player's scoring, their credits remaining and the ball-in-play were all digital and being displayed on the seven-segment gas plasma displays.

Even once they dropped the chimes and 'noisemaker' (for [[World Cup]] in May 1978) and added a digital sound board, the operator could still select the more familiar 'bings & bongs'. A switch was provided on the sound board which allowed selection of simple digital chimes. This option persisted right through on System 3 to System 7 sound boards, but for the most part was not used. Digital sound became more popular as time went on. 

The design of System 3 was based on the Motorola 6800 CPU and what has become a standard arcade peripheral I/O device, the 6821 PIA (originally the 6820). The PIA (or Peripheral Interface Adapter) on the MPU boards was used to drive the display I/O. All other peripherals, switches, lamps, solenoids, and sound, are driven by the 3 PIAs on the driver board.

System 3 and 4 boards use a Motorola 6800 microprocessor with a 6875 clock generator chip, while System 6 and 7 boards use either a 6802 or 6808 microprocessor. You cannot use a 6802 or 6808 in a System 3 or 4 board! The chips are not backwards compatible.
 

====Upgrading a System 3 board to System 4====
[[File:System3ToSystem4ConversionOverview.jpg|thumb|left|300px|Overview of a board converted from System 3 to System 4]] 
A system 3 MPU can be upgraded to use a single 2716 EPROM at what will be IC14 (System 3 schematics do not give this IC position a designation number). This essentially converts the board to a System 4 board. This upgrade is useful to reduce the number of sockets (and failure points). Install a 24 pin socket at the unpopulated area, just to the right of the IC17 socket. Combine the original game ROM code into a single 2716, and install it into the socket of what is now being called IC14. The flipper ROMs are installed in the same locations, ROM 1 into IC20, ROM 2 into IC17. 

[[File:CutJumperWMSSystem3ToSystem4.jpg|thumb|right|300px|IC15 (on left), showing necessary cut and jumper]] 
Procedure:
#Locate IC15 on the MPU (see picture at left)
#Locate the trace that runs from between pins 6 and 7 of IC15 to a via just to the right of the chip
#Sever that trace carefully
#Using jumper wire, connect the through hole via to pin 1 of IC15.
 

Doublecheck the work once the jumper is installed. Perform a continuity test between pin 1 and pin 9 of IC15. There should not be continuity. Conversely, there should now be continuity between pin 1 of IC15, and pin 20 of IC14. 

[[File:WMS Sys3 Remove Components.JPG|thumb|left|300px|Components which must be removed from a stock System 3 MPU board]] 
The System 3 MPU board reset circuit should be updated as follows. This update was recommended by Williams in manual amendment 16P-482-110, and is done to improve CMOS RAM memory content protection during power-on/power-off. 

[[File:Added10K.jpg ‎|thumb|right|300px|10 Kohm 1/4W resistor added to circuit, upper left, connected to the banded end of the zener diode.]]
Procedure:
#Remove C27, R30, and R40 from the upper left corner of the MPU
#Install a 10 Kohm 1/4 watt resistor. One leg of the resistor will be soldered to the cathode of ZR1 (banded side - top). The other leg of the resistor will be soldered to the left through hole where R30 formerly was. The newly installed 10 Kohm resistor is referred to as R96 in System 4 MPU schematics.
 

[[File:1N4148.jpg|thumb|left|300px|Addition of the D19 1N4148 diode installed]] 
Add a 1N4148 diode, if it is not already installed. The location is in the upper left quadrant of the circuit board. The anode (non-banded side) of the diode should be installed in a via, which is just to the right of resistor R23. This via is routed to pin 17 of IC19. The cathode (banded side) of the diode should be tack soldered to the solder pad where the right leg of resistor R23 is installed. Once installed, this 1N4148 diode is referred to as D19 on System 4 MPU schematics. .

[[File:WMS Sys3 MPU Sockets.JPG|thumb|left|300px|Addition of C68 is shown above, a .1uf 50v ceramic capacitor]] 
Install a .1uf 50v capacitor just below the newly installed IC14 socket. One leg of the capacitor connects to +5VDC, while the other leg is inserted into a via which is routed to the /RESET line.
 

[[File:WMS Sys3 Clock Circuit.JPG|thumb|left|300px|A factory board without the recommended capacitor and inductor update.]]
[[File:System3Mod.jpg ‎|thumb|right|300px|The recommended capacitor and inductor additions have been made to this board.]] 
Add a 120pF capacitor (C66) and a 15uH inductor (L1) in parallel with the R1 resistor located just to the left of the crystal. This modification also applies to System 4 boards which do not have these components installed.
 

[[File:WMSSys3CapUpdate.jpg|thumb|left|300px|Here, the originally installed capacitor has been replaced with the correct capacitor.]] 
Finally, some System 3 MPUs came from the factory with a .01uf capacitor (marked 103) installed at position C22, (located just below IC19, the 5101 RAM). If so, replace that capacitor with a .1uf 50v capacitor. The purpose of this capacitor is to snub the high frequency noise created within the 5101 as silicon gates open and close. This applies to System 4 MPU boards too. 

Once the above modifications are performed, a System 3 MPU board will be one-to-one compatible with a System 4 board.
 

===System 4===
[[File:WMS sys4 MPU board.JPG|thumb|left|300px|Williams System 4 MPU Board]]
[[File:WilliamsSystem4MPU.jpg ‎|thumb|right|300px|Another view of the Williams System 4 MPU Board]] 

The System 4 architecture is little changed from the previous System 3 generation. The only functional changes from System 3 to System 4 was a minor alteration to the reset circuit as well as minor changes to the data and address bus in order to more easily facilitate the use of larger EPROMS for the game specific programming.

System 4 machines began with Pokerino in 1978 and ended with Flash in 1979. Late production Flash machines also utilized the then-new System 6 boardset in place of System 4.
 All System 6 software will run on a System 4 board. The exception is Firepower which utilized both the bipolar proms and a 2716 game eprom. Due to the missing memory protection circuit and somewhat unstable clock circuit replacing a System 6 CPU with a System 4 CPU is not recommended.
 

====Upgrading a System 4 MPU Board====
[[File:WMS Sys4 Clock Circuit.JPG|thumb|left|300px|Changed layout with additional capacitor and inductor to the R1 resistor]] 
The System 4 board has a revised clock circuit which usually does not need to be modified. If there are reset problems, replace the 22ufd tantal capacitor with a 33ufd type. This will lengthen the reset period a little and helps the clock circuit to stabilize. The capacitor modification can also be applied to System 3 boards. 

If an incorrect capacitor is installed at position C22, (located just below IC19 - 5101 RAM), it is recommended to replace it. This replacement is only necessary, if a 0.01mfd cap is installed. If so, replace the 0.01mfd capacitor with a .1mfd 50v capacitor. This applies to System 3 MPU boards too. Only early system 4 boards had an incorrect capacitor installed. Also check if the 0.01mfd blocking capacitor for IC14 is missing. If yes stuff it.
 

===System 6===
[[File:SYS-6-MPU-board.jpg|thumb|left|300px|Williams System 6A MPU Board. Note that the .156 headers on this board have been replaced and an LED indicating the blanking status has been added]] 
System 6 was an upgrade to the System 4 design, replacing the 6800 processor with a 6808. They took advantage of the internal clock in the 6808 CPU, removing the need for the 6875 clock generator (a companion chip to the 6800 and now obsolete and impossible to find).

This also changed the way the 'watchdog' circuit functioned. The watchdog monitors the CPU (IRQ signal), and will blank the displays and lamps as well as stopping the solenoids from firing. When something goes wrong (perhaps the MPU board has locked up), 'blanking' should prevent further damage to the game by 'locked on' coils and other output components driven from PIAs on the MPU/Driver boards.

More ROM memory could be addressed, and this was used to hold more sophisticated game code. As an example, Firepower used a 2716 2K Game ROM (which was standard for IC14) plus 3 x Harris bipolar proms (512 bytes each) giving a total game code size of 3,584 bytes. Having just 3K of code space is nothing by today's standards. Programmers had to work hard to get good game code in such a small space.
 

During early System 6 revisions the transceiver chips 8T28 ICs at IC9 and IC10 were found to not be needed. They were eliminated from the design as they didn't need to amplify signals to and from the data bus with modern ROMs. If the ICs are working, leave them alone. But if not, these buffers are obsolete and can be removed and bypassed, in effect by jumpering the data bus pins of the CPU directly to the data bus. i.e. IC9 and IC10 may be removed, and jumpers installed across pins 2-3, 5-6, 9-10, and 12-13 for both ICs.

Also around this period of game development, 8T97 bus "amplifier" ICs at IC3, IC4, and IC8 were used for address and control signals from the 6808 to peripheral ICs. 8T97s are long obsolete too, but fortunately can be replaced with an 74LS367, which Williams itself used in some revisions of the board. 8T97s can not be removed and jumpered like IC9 and IC10. They must be in place. Testing these chips is easy with a logic probe. The input signal should closely match the output signal of the amplifier. i.e. pins 2/3, 4/5, 6/7, 10/9, 12/11, and 14/13 should all test identical with a logic probe. Note that since the signal is amplified, logic probe indicators might vary somewhat. But, the probe should not measure high on one pin and low on the companion pin, for example.

The 8T97 bus amplifiers communicate the following signals.

*IC4 - A0 thru A5
*IC3 - A6 thru A11
*IC8 - A12 thru A15, VMA (valid memory address), and R/W (read/write)

On Firepower alone, the 'Combo ROM' modification must be done to allow the use of a 2732 EPROM as the Game ROM at IC14. This replaces the Firepower game code found in 4 ROMs as described [[Modifying a System 6 or 6A to Use The Firepower 2732 Combo ROM at IC14 | here]], and is an excellent idea. Less chips to worry about, less sockets to replace.

Williams also transitioned to using the updated 6821 PIAs during System 6 because the MC6820 was phased out after 1977.
 

==== Replacing the 6808 with a 6802 ====
[[File:WMS Sys6 Jumper1 6808.jpg|thumb|left|300px|J1 installed for 6808 or 6802 CPU chip]]
[[File:WMS Sys6 R4 6802.jpg|thumb|right|300px|J1 removed, 4.7 Kohm 1/4w resistor (R4) installed for use with 6802 CPU chip]] 
The typically stuffed 6808 microprocessor can be replaced with the more easily obtained 6802 microprocessor. The 6802 uses the same instruction set architecture and pinout, making it "backward compatible" with the 6808. The 6802 incorporates an internal 128 x 8 bit RAM memory. With the proper strapping, the 6810 RAM located at IC13 may be removed when a 6802 is installed. Factory strapping grounds pin 36 of the 6808/6802 socket via jumper J1. Pin 36 must be pulled high by tying pin 36 to 5V via a 4.7K pullup resistor. This enables the 6802's internal RAM. The 6810 at IC13 can then be removed or (if not socketed) simply left in place. 

'''Procedure'''
*Replace the 6808 with a 6802
*Remove jumper J1
*Install a 4.7K resistor at R4

Officially, the 6808 has no internal RAM. But, internally it's identical to the 6802. Sometimes the 6808 internal RAM works but this is not guaranteed, so when using a 6808, be sure pin 36 is grounded.
 

====Factory Jumper on System 6 MPU Board====
[[File:WMS Sys6 Header Jumper.JPG|thumb|left|300px|Williams System 6 MPU board with factory jumper]] 
[[File:WMS Sys3 and 6 Header Compare.JPG|thumb|right|300px|Williams System 6 and System 3 MPU board comparison]]
Some System 6 MPU boards have a jumper installed between IJ3 pin 1 and IJ4 pin 1. This is a factory jumper, and should not be removed. Its purpose is due to the addition of the memory protect circuit, which was incorporated with the System 6 MPU. System 3 and 4 MPU boards did not have a memory protect circuit. The method in which this was added is the addition of pin 1 of IJ4. This pin was formerly the keying pin on System 3 and 4 MPU boards. However, Williams failed to run a trace to this pin for the memory protect circuit. Hence, a jumper was installed. 

If using a System 6 MPU board in a System 3 or 4 game, it is recommended to remove the keying plug from the IJ4 connector in the game, as opposed to cutting / removing pin 1 or IJ4. This will allow the MPU to be used in any System 6 games in the future.
 

===System 6A===
[[File:WMS sys6a MPU board.JPG|thumb|left|300px|Williams System 6A MPU Board]]
The System 6A MPU is a System 6 board without buffer chips at IC9 and IC10. In place of these chips were several jumpers in closed frames, which can look similar to a socket at first glance. The jumpers are used to pass the data lines from the CPU chip to the data bus.

System 6A also used four 7-digit slave displays and one 4-digit slave display driven by a centralized display driver board. This separated the displays from any board logic. Prior to this point, a master display driver board (with a 6-digit or 4-digit glass installed directly on the driver board) housed the display logic and drove four 6-digit slave displays.

Some System 6 boards that are not explicitly marked as 6A in the lower right corner were modified to be 6A boards, which can be identified by the lack of the IC9 and IC10 buffer chips. Either several uninsulated wire jumpers will be installed in the solder pads of these two chips, or the same closed frame jumpers as seen on actual 6A MPU boards may be present.
 

====Modifying a System 6 or 6A to Use The Firepower 2732 Combo ROM at IC14====
[[File:WMS IC14 4700 Res 20 24.jpg|thumb|left|300px|Cuts made, jumper run, and 4.7Kohm resistor added]]
[[File:WMS J3 J4 1N4148.jpg|thumb|right|300px|2 1N4148 diodes added where jumpers J3 & J4 previously were]] 
The factory ROMs for Firepower use all 6 ROM socket positions on a System 6 or 6A board. To minimize the amount of chips and sockets used, some modifications have to be performed to the MPU board. In doing these modifications, the board will then be able to use "standard" green flipper ROM chips at IC20 & IC17, and a single 2732 combo ROM at position IC14. Below are instructions pulled from the readme.txt file, which is included with the Firepower L2 ROM code found on [http://www.ipdb.org/machine.cgi?id=856 www.ipdb.org]. Some of the procedure wording has been altered for clarification.

There are similar methods which may or may not work besides this method. Note that the jumper wire can be connected from IC14 pin 21 to either IC30 pin 14 or pin 36 of the 40 pin interconnect. If at all possible, please make sure that the board being modified boots and works with other game code, such as Gorgar, Flash, or Firepower, before attempting to make these modifications for the Firepower combo ROM. 

#Remove Game ROMs (IC14, IC21, IC22, IC26) from their sockets.
#Remove jumpers that may be installed at J3 or J4 (to the right of IC15, a 74LS139).
#On the solder side of the board, at IC14 pin 21, sever the trace on both sides of the solder pad. Removing the existing solder on the pad may help. The idea is to sever the +5V connection to the pin, while still leaving the solder pad at the pin itself.
#On the solder side of the board, install a jumper from IC14 pin 21 to IC30 pin 14. IC30 is generally not installed. It is a 16-pin chip outline just to the right of IC14 and just above the 40 pin interconnect. Solder the jumper between the hole at pin 14 of the empty IC30 location, and pin 21 of IC14, making sure to not short it to the other side of the trace previously cut at IC14. This connects A11 to IC14.
#On the solder side of the board, install a 4.7K ohm, 1/4 Watt resistor between pins 20 and 24 of IC14. With the resistor leads bent at 90 degrees at a comfortable distance from the body of the resistor, the legs should line up at just the right spacing to solder one lead to each of those pins. Again, make sure to avoid shorting the pin 20 connection to the jumper wire at pin 21, or the cut trace edges around pin 21. This provides a pullup for the active-low chip select.
#Install two fast switching signal diodes (either 1N914 and 1N4148) at locations J3 and J4. The cathode (banded) end should be oriented toward the TOP of the board for both diodes. This enables both of the two Game ROM address ranges to drive the active-low chip select at IC14.
#Program a 2732 with the "FPCOMBO" ROM image and install at IC14. If the board doesn't already have working Green Flipper ROMs at IC17 and IC20, those should be installed also. Note the orientation of the ROMs with respect to pin 1 of the chip sockets.
 

===System 7===
[[File:Sys7-MPU.jpg|thumb|left|300px|Williams System 7 MPU Board]]
System 7 was considered a major step change. It had a redesigned MPU board, now supporting a single 7-segment LED display for indicating improved diagnostic information instead of the original 2 LEDs that System 3-6a MPU boards had used. It also added commas to the player scoring displays and moved the sound select support to the MPU board. An extra 6821 PIA supported both the sound/speech selects and the display of commas. An extra 12-pin header at 1J8 was added to provide connections for the new Sound and Commas support. This freed up five solenoid drives at positions #9-13 on the Driver board, which had been sound/speech selects. They were then available to drive extra game Coils or Flash Lamps.

The MPU used two 2114 Static RAMs; these 1024 x 4 bit RAMs replaced the use of 6810 RAMs mentioned above. There was extended memory addressing, support for multiple 2732 ROMs (or EPROMS) as standard and a huge number of jumper selections available. The jumpers support various memory addressing schemes and ROM sizes, making the System 7 board MPU "backwards compatible" and able to emulate any of the previous System 4-6a games. (Provided, of course, that the correct Jumper Settings and EPROMS are installed.)

The Sound and Speech boards were unchanged for System 7; both sound and speech boards remained compatible from their introduction for Gorgar. In some cases the System 7 game had no 0.100" 40-way IDC header for the speech board connection. This was a cost saving measure made by Williams for games produced without speech. This connector is cheap and available today as it is still used for PC IDE hard drives and modern PCB connections. Adding this connector back to the sound board allows it to support a speech 'daughter board' by removing the Jumper at W1.

The Driver Board mates with the MPU board using 40 x 0.156" header pins on the MPU and female sockets on the Driver Board. This is a continual source of repair problems for this era of Williams machines. To solve this, when designing System 9 Williams combined the MPU and Driver Boards (and the Sound Board) onto a single PCB (Printed Circuit Board), and removed the problems associated with the now infamous Williams "40-way" connector. Only the speech board remained separate, as digital speech was considered an optional feature.
 

====System 7 MPU Jumper and IC Locator====
[[File:WMS Sys7 MPU Jumpers Marked.JPG|300px|left|thumb|Positions of the jumpers on a System 7 MPU board]]
[[File:System7ICLocator.png|300px|right|thumb|IC Locations on a System 7 MPU board]]
System7ICLocator.png
 
The image at left shows the most common jumpers on a System 7 MPU board. There are other jumpers on the right hand side of the board (not shown in the pic). However, these jumpers are rarely added or removed, nor do they pertain to the size of the ROM chips installed on the board.

The image at right is provided to assist in IC location.
 

The factory release of most System 7 MPUs contained a 2532 PROM at IC17. The more common 2732 is easy to use, with minor board modifications.

[[File:WMSSystem7MPUJumper.jpg|300px|left|thumb|Component side of a System 7 MPU board with modifications for a 2732 at position IC17]]
[[File:WMS Sys7 MPU 2732 IC17 Mod.JPG|300px|right|thumb|Solder side of a System 7 MPU board with modifications for a 2732 at position IC17]] 
#'''On the component side of the board,''' move jumper 22 to jumper 23. This amounts to moving the jumper down one position.
#'''On the solder side of the board,''' cut the fat trace that grounds pin 21.
#Jumper from the via labeled "22" to pin 21 of IC17. Be sure that the jumper doesn't short to the jumper previously moved on the component side.
 

====System 7 MPU Test Pad Info====

There is an unpopulated connector in the lower right corner of the system 7 MPU board. You can use a meter or logic probe to test the signals that are present on it or possibly add a connector to it (you can use a .100 dual row 20x2 connector).

[[file:Williams-sys7-unpopulated-connector.jpg|thumb|left|300px|Unpopulated Connector]] 

{|class=wikitable
|-
|gnd || 40 || 39 || gnd
|-
|d7 || 38 || 37 || ic36 CA2
|-
|d6 || 36 || 35 || ic37/15
|-
|d5 || 34 || 33 || ic37/14
|-
|d4 || 32 || 31 || ic37/13
|-
|d3 || 30 || 29 || ic37/21
|-
|d2 || 28 || 27 || ic36 pb4
|-
|d1 || 26 || 25 || ic36 cb2
|-
|d0 || 24 || 23 || blanking
|-
|reset || 22 || 21 || vma
|-
|r/w || 20 || 19 || bus 02
|-
|a14 || 18 || 17 || a15
|-
|a12 || 16 || 15 || a13
|-
|a10 || 14 || 13 || a11
|-
|a8 || 12 || 11 || a9
|-
|a6 || 10 || 9 || a7
|-
|a4 || 8 || 7 || a5
|-
|a2 || 6 || 5 || a3
|-
|a0 || 4 || 3 || a1
|-
| +5vdc || 2 || 1 || +5vdc
|-
! colspan="4" | Bottom of board
|}

===MPU Compatibility===
Williams 3-7 MPU are pretty flexible. With some modifications, boards can be upward compatible, while others are downward compatible.

Here are the details:
*A System 3 MPU can be upward compatible to a System 4 MPU, if the upgrades are performed as described [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Upgrading_a_System_3_board_to_System_4 above]. And if a System 3 MPU is upgraded to a System 4 MPU, it is then upward compatible with a System 6 MPU board. There will not be a memory protect circuit though. 
*System 4 and 4A MPUs are upward compatible to a System 6 MPU, when a socket is installed and used at position IC14. However, there will not be a memory protection circuit. A System 4 MPU is backward compatible with a System 3 MPU with no modifications performed. 
*System 6 and 6A MPUs are backward with System 3, 4, and 4A MPU boards with no modifications performed. 
*A System 7 MPU is backward compatible with System 3, 4, 4A, 6, and 6A MPU boards. However, board jumpers will have to be removed / installed. It not recommended to use a System 7 MPU board in any previous systems, but it can be done. 
*System 3, 4, 4A, 6, and 6A MPU boards are '''not''' upward compatible with System 7 MPU boards.

In any instance where a non-native MPU board is used in place of the original MPU board, the correct flipper ROMs and game ROM must be installed. An example would be if an upgraded System 3 MPU were to be used in Gorgar. The GREEN flipper Roms and Gorgar game ROM would have to be installed in postions IC20, IC17, and IC14.
 

===Aftermarket Boards===

[[File:RottendogMPU327.jpg‎|300px|thumb|left|A Rottendog MPU327, which can be installed in any Williams System 3 - 6 game.]]
[[File:MPU327StuffedWrong.jpg‎|300px|thumb|right|U17 on an MPU327, stuffed correctly with a 74HCT9114.]]
[http://www.rottendog.us/?product=mpu327 Rottendog] offers aftermarket Williams 3 through 7 combined MPU/driver boards. The Rottendog board (pictured left) contains all the game code for every System 3 through 6 game. The game code is DIP switch selectable. Note that the "sense" of the DIP switch bank is backwards. Follow the on-board silkscreen to the left of the DIP switch. 
'''Note: as of January 2018, Rottendog is no longer claiming support for System 7 games with their MPU327 board.

Some '''older''' Rottendog MPU327s were stuffed wrong at the factory. U17, which services the switch columns, should be stuffed with a 74HCT9114. In some boards, that location is stuffed with a 74HCT244, which will not work correctly. Note that there are several revisions of the MPU327 board.
 

[[File:RottenDogMPU327Short.jpg‎|300px|thumb|left|A Rottendog MPU327, installed, and shorted to a switch matrix header pin. Image provided by Tony, PinSider "goingincirclez". Used with permission.]]
[[File:RottenDogMPU327ShortCorrection.jpg‎|300px|thumb|right|One user's (excellent) correction for the situation. Image provided by Tony, PinSider "goingincirclez". Used with permission.]] 
The RottenDog MPU327 PCB design causes the switch matrix row header (2J3) to short to a mounting bracket as shown at left. This can cause the switch column IC at U17 to fail. A simple correction for this issue is shown at right. See the [https://pinside.com/pinball/forum/topic/warning-to-rottendog-327-owners-check-it-now original Pinside thread] for additional details.
 

[[File:RD 327 MPU Combo Dipswitch.jpg|300px|thumb|left|Rottendog MPU327 game select dipswitch bank]] 
Note that the dipswitch bank used for selecting a specific game has 8 dipswitches, whereas only the 6 switches on the right are the only ones used. The 2 left dipswitches must be turned "on" (opposite of what is expected of a dipswitch) to "0".
 

==Driver Boards==
===System 3-6===
[[File:WMS Sys3-6 drvr.JPG|thumb|right|300px|Williams System 3-6 Driver Board]]
The driver board uses three 6821 Peripheral Interface Adapter (PIA) chips to drive:

* an 8x8 Matrix for the Lamps
* an 8x8 Matrix for the Switches
* Solenoids and Sound Selects

More properly, the PIAs were used to drive transistors that in turn drive the lamp matrix, switch matrix, and solenoid circuits. In the case of the solenoids, Darlington transistors are used as "solid state relays", providing a path to ground for coil power, causing them to energize.

The electronic design choices Williams made became the basis for all subsequent Bally/Williams pinball games and even games being made today. The specific CPU and PIA ICs may change, more memory and ROM space is available to the programmers, MOSFETs are used as the switching relays instead of transistors...yet the basic design established for the lamp matrix, switch matrix, and for energizing coils, remains unchanged.
 

===System 7===
[[File:WMS Sys7 drvr board.JPG|thumb|left|300px|Williams System 7 Driver Board]] 
The driver board remained almost completely unchanged from System 3 right through to System 7 with the exception of one small change that was made to the driver board during System 7. Eight resistors were changed to zero-ohm jumpers in the switch matrix inputs to increase sensitivity and responsiveness. These zero ohm resistors are located in the upper right corner of the driver board.
 

===System 7 Hyperball Specific Driver Board===
[[File:HyperBallSpecificDriverBoard.jpg|thumb|left|300px|Williams System 7 Hyperball Specific Driver Board]] 
Since Hyperball didn't need to drive coils other than the cannon coil and the auger motor, and since it needed to drive many more lamps than a normal pinball game, Williams created a unique, special purpose variant of the driver board specifically for Hyperball. This driver board can only be used in Hyperball, and a regular System 3 through 7 driver board can NOT be used in Hyperball.
 

==Power Supplies==
[[File:WMS_Early_Sys3_Power_Supply.jpg|thumb|300px|left|Early Williams System 3-6 Power Supply]] 
The System 3-6 power supply used in [[Hot Tip]] and [[Lucky Seven]] have a few additional components that later games did not need, physically located a little above the row of four fuses: two .22mfd mylar capacitors and two 1N4001 diodes. If a later power supply is being installed in Hot Tip or Lucky Seven, these components must be added to the board if they are missing.

Williams continued to populate these components for several following games, but they were not utilized. These components can be safely left populated or simply removed from the board. 

[[File:WMSSystem7PowerSupply.jpg|thumb|300px|left|Williams System 7 Power Supply (GI input connector modified from stock)]] 
Note that the parts bill of materials for some (perhaps all) system 7 games call out a 2N6087 power transistor for Q5. This is most likely a typo. A 2N6057 or 2N6059 should be used.
 

==Flipper Power Supply==
<center>
<gallery widths=400px heights=200px perrow=2 caption="Williams System 7 C-9939 50V Flipper Power Supply Board">
File:C-9939-Front.jpg|<center>Front</center>
File:WMS-C-9939-Back.jpg|<center>Back</center>
</gallery>
</center>
This PCB was first used in Hyperball to control the auger (ball lift) motor. As seen in the pictures above, the PCB layout was designed to accommodate more components than were ever stuffed. This is because this same board, using different components, is used in some Williams video games. In Firepower II, Laser Cue and Star Light the trimmed down version shown here provides the flipper coils with 50VDC power. The AC voltage supplied to the bridge rectifier originates from a second, smaller, transformer mounted on the wooden plank in the bottom rear of the cabinet.

Since the coil voltage this board provides is exactly the same as that of later System 11 games, far stronger Williams coils, such as the FL-11630, can be used in these games. It's advisable when using these coils to install a 2.2µF capacitor across each EOS switch, to reduce spark across the EOS switch, as was done in later Williams System 11 games.

The board suffers from cold solder joints at the header pins (at least). As shown in the picture above, someone did a (poor) job of reflowing the solder on the header pins. A better solution would be to replace the header pins altogether.

The exact same board is used in all System 9 and early System 11 games up until F-14 Tomcat. Data East copied this design. Hence, this 50VDC Power Supply can be used in Data East games from Laser War to Time machine.
 

==Sound Boards==

During the long run of System 3 through 7 games, Williams used two basic board types, designated Type 1 and Type 2

===Type 1 Sound Board===

[[File:WMSType1SoundFront.jpg|300px|thumb|left|Williams Type 1 Sound Board front]]
[[File:WMSType1SoundBack.jpg|300px|thumb|right|Williams Type 1 Sound Board back]] 
The Type 1 sound board is rectangular in shape as pictured at left. Two versions of this board were manufactured. One version placed the 12,000uf 5V filter capacitor vertically. The other version placed the same capacitor horizontally. The boards function identically.
 
As can be seen on the back of the board pictured at right, the board was modified from the factory to add 3 jumpers (the three longer red wires) to make it work correctly. Every Type 1 sound board should have these jumpers. Note: The factory installed jumpers take advantage of trace "vias" to accomplish these connections.

#A long jumper that connects the reset pins on the 6821 PIA (pin 34) and the 6802 (pin 40)
#Pin 40 of the 6802 also needs to be jumpered to pin 36 of the 6802 for the reset circuit to be complete.
#Jumper pin 35 to pin 8 of the 6802. This ties Vcc1 and Vcc2 together.

Williams documented additional modifications in the "Flash" manual. The board pictured has been updated with all of these modifications. A drawing of these modifications and jumpers can be found [https://www.pinwiki.com/wiki/images/d/d5/Sojueen.pdf here].

The modifications are:
#Add a jumper between pins 39 and 40 of the 6821 PIA
#Add two 10K, 1/4W resistors
#(Possible) replace two 100K resistors with 4.7K, 1/4W resistors. Note that some boards shipped with 4.7K resistors installed.

'''Modifications 1 and 2''' "reduce the susceptibility of the sound board to noise". The "noise" can cause the board to stop execution after a short time, especially when using a 9316B or 2716 ROM. If a sound board makes sound after pressing the diagnostic button, but either makes no other sound, or makes sound for a short time and then quits, these two mods will probably fix this problem.
'''Modification 3''' "improves the quality of the sound produced at the speaker".

'''Theory of Operation'''

The Type 1 sound board is about as basic as a sound board can be.

*A 3.58Mhz crystal provides the clock signal across pins 38 and 39 of the 6802.
*A simple reset generator is configured with Q1, Q2, and CR3 (a 6.8V zener diode). As the unregulated 12VDC rises past 6.8V, the zener breaks down, eventually allowing pin 40 of the 6802 to be pulled up to logic high (5V).
*A diagnostic pushbutton, upper right, grounds the NMI (non-maskable interrupt) signal to the 6802 processor and causes the board to play a diagnostic tune (in most cases).
*A two position switch selects between "sounds" (right) or "chimes" (left).
*A volume adjustment POT is located on the board itself, and is a 5K POT.
*A 6802 microprocessor controls the board via a 6821 Peripheral Interface Adapter (PIA).
*The board does not have a RAM IC (like a 6810). Instead, the built-in 128 bytes (yes, 8-bit bytes) of RAM on the 6802 are used.

Power is provided from the transformer secondary at connector 10J1.

*Pins 1,2 - 9VAC
*Pins 5,6 - Ground (center tap)
*Pin 7 - Key
*Pins 8,9 - 9VAC

Power is fused and rectified via the "in-line" bridge rectifier immediately below the connector.
Positive unregulated 12VDC is filtered by a 12,000uf/25V electrolytic capacitor.
Negative unregulated -12VDC is filtered by a 1,000uf/25V electrolytic capacitor.
The positive unregulated 12VDC is regulated down to 5VDC via a 7805 regulator at IC11.
These three voltages, plus ground, define the power requirements for the board.

A speaker is connected to 10J2, positive to pins 1/2, ground to pins 3/4.

Sound selects are presented by the driver board to the sound board at connector 10J3. Selecting a particular sound is a matter of grounding the appropriate sound select pins which are normally held high via 4.7K pullup resistors at R37 through R44. Each signal is buffered via the 4050 non-inverting hex buffers at IC8 and IC9.

Each of the sound select signals is connected to both a 4068 8-input NAND gate and to the (software configured) input port of the 6821 PIA (PB0-PB7). The output of the 4068 is connected to pin 18 (CB1) of the 6821 which is configured by the sound board software to create an interrupt to the 6802 processor. When the 6821 PIA interrupts the processor, the interrupt servicing routine reads the input port (PB0-PB7) of the PIA to determine which sound was commanded. The processor pulls sound data from the sound ROM and pushes the data to the 6821 PIA (software configured) output ports (PA0-PB7) one 8 bit byte at a time. The PIA output port signals drive a simple 1408 DAC (digital to analog converter) which produces the analog signal that is stabilized and eventually amplified by a TDA2002 audio amplifier.

'''What Goes Wrong'''

The Type 1 sound board shares most of the common faults associated with the Williams System 3-7 board set. Chief among them are:
#ScanBe sockets. These are well documented to be long past their useful life and should always be replaced.
#Fractured solder joints at the header pins. The Williams manufacturing process trimmed the .156 header pins too short, damaging the solder meniscus. Over time, these solder joints develop fractures. The header pin eventually begins to work itself out of the joint which causes reliability issues.
#Aged electrolytic capacitors. At the very least, the 12,000uf/25V 5VDC filter capacitor should be replaced. Replacing all of the electrolytic caps is advised. Following is the capacitor parts list.

'''Electrolytic Capacitors Used'''

*C10 - 25uF, 25 Volt Axial (can use 22uf)
*C13 - 500uF, 16 Volt Axial (can use 470uf)
*C14 - 800uF, 16 Volt Axial (can use 1000uf)
*C27 - 100uF, 10 Volt Axial
*C29 - 12000uF, 16 Volt Axial
*C30 - 1000uF, 16 Volt Axial

[[File:WMSSystem3-4RectangularSoundBoard.jpg|300px|thumb|left|Williams Type 1 Sound Board Version 2 with the horizontal cap, front]]
[[File:Type1soundBoardHorizontalCapBack.jpg|300px|thumb|right|Williams Type 1 Sound Board Version 2 with the horizontal cap, back]] 
These images show a Type 1 sound board that was introduced later in production. The 5VDC filter capacitor was turned horizontally. Also, an extra connector was added to enable a remote volume POT. Note that this sound board has been "recapped".

This revision of the sound board picked up the jumper modifications of the earlier board in the PCB design, with one exception. Pins 39 and 40 of the 6821 need to be bridged (or jumped) to avoid the board locking up after a short (and random) period of time. A solder bridge can be seen at pins 39 and 40 of the sound board pictured at right.
 

[[File:WMSType1SoundBoardJumper.jpg|300px|thumb|left|Williams Type 1 Sound Board Version 2, closeup of jumper to enable onboard sound POT]] 
Later production Type 1 sound boards added a connector to enable a remote volume POT. If the remote POT is not used and the onboard POT is used instead, a jumper must be installed between pins 1 and 2 of this connector. The pictured jumper is quite Gucci. A simple wire jumper on the back of the PCB will suffice.
 

====Type 1 Sound Board Jumpers====
[[File:WMSType1SoundFront.jpg|300px|thumb|left|Williams Type 1 Sound Board]]
The Type 1 Sound board can be jumpered to use a 7641 masked ROM, a 9316B masked ROM, or a 2716 (or doubled 2732). The board pictured at left is jumpered to accept either at 9316B or a 2716. To use a 7641 masked ROM, remove the four jumpers to the right and just below the sound ROM, and install the opposite set of four jumpers. 

===Type 2 Sound Board===
<center>
<gallery widths=400px heights=400px perrow=2 caption="Williams System 6-7 Type 2 Sound and Speech Boards">
File:WMS Sys6-7 sound.JPG|<center>Williams System 6-7 Type 2 Sound Board</center>
File:WMS Sys6-7 sound speech.JPG|<center>Williams System 6-7 Type 2 Sound Board with Speech Board Connection</center>
File:WilliamsType2SoundAndSpeechBoarfPair.jpg ‎|<center>Williams System 6-7 Type 2 Sound Board with Speech Board. Note that this -3 revision board features a tantalum capacitor soldered directly between test point 1 (+12VDC) and test point 3 (ground). In later board revisions, this part was added to the PCB design.</center>
</gallery>
</center>

==Speakers==
With the exception of Hot Tip and Lucky 7, all Williams System 3-7 games use a speaker. And, nearly all of them use a single 6-1/2" speaker located on the cabinet bottom (later games, like Firepower II, had an oblong speaker below the smaller backglass instead). Speakers used during games such as Firepower were 8 ohm 5 watt.
 

==Displays==
[[File:WMS sys3-6 master display.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Using UDN7180A - Common)]]
[[File:WMS Sys3-6 Master Display NE584.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Using NE584 - Less Common)]]
[[File:WMS sys3-6 master display discrete.JPG|300px|thumb|left|Williams System 3-6 Master Display Board w/ Discrete Components]]
[[File:WMS-SYS6-displays.jpg|300px|thumb|left|Williams 6-Digit Slave Displays]]
[[File:WMS sys6a-7 display drvr.JPG|300px|thumb|left|Williams System 6A-7 Display Driver Board]]
[[File:WMS-SYS7-displays.jpg|300px|thumb|left|Williams 7-Digit Slave Displays]]
[[File:Bowler6DigitFace.jpg|300px|thumb|left|Williams 6-Digit Puck Bowler Display Glass]]
[[File:Bowler6DigitBottom.jpg|300px|thumb|left|Williams 6-Digit Puck Bowler Display Edge Connector]]
 

==Other Boards==

==Flippers==

==Drop Target Banks==
===First Generation Drop Target Bank===
[[File:WMS Horseshoe Drops.JPG|200px|thumb|left|Typical first generation Williams solid state drop target bank (Time Warp)]]
Starting with the first Williams solid state game, Hot Tip, Williams introduced their version of the solid state drop target bank. Drop target banks were a rather new design for Williams. They were the last major pinball manufacturer to introduce the drop target bank earlier in 1977 with the electromechanical game, Big Deal. And, only 3 games prior to the solid state version of Hot Tip, including the electromechanical version of Hot Tip, were manufactured with drop target banks. 

The reason for mentioning the background regarding Williams drop target banks is because of the actual design implemented. There is one distinct difference between Williams drop target banks and any other manufacturer's drop target bank. In addition to using a scoring switch for each drop target in a bank, Williams used a secondary set of switches paired in series to detect when all of the drop targets were physically dropped. The drop target bank frame, reset coil or coils, appearance of the drop target faces on the playfield, and operation of the bank was virtually the same between Williams electromechanical games and solid state games. Therefore, it is believed that Williams designed their banks this way, because they had not been designing drop target banks that long, and decided upon a legacy approach. In other words, the Williams solid state drop target banks used hardware instead of software to detect when all the drop targets were down.
 

[[File:WMS Horseshoe Drops Back.JPG|200px|thumb|left|Backside of Williams first generation drop targets]] 
The design of the drop targets are very different from any other manufacturer's design. Unlike Bally, Stern, or Gottlieb, the Williams drop target is a meaty, reinforced plastic which is fairly consistent in thickness and width throughout the target. Williams does not use a face with a long neck stemmed down in size. The benefit to this design is that breakage is minimized. The downside to this design is extra added weight. There are several other design differences too, such as the compression spring used to pull the target down. It is physically screwed to the front of the drop target plastic, as opposed to being attached via a molded "hook" like other manufacturers. This too is a plus, because the molded hooks on other drop target systems are prone to breakage. However, probably the most recognizable difference is the drop target switch design. On the back side of a Williams drop target, a switch triggering mechanism in the form of a copper horseshoe with two contacts is physically screwed to the plastic. The combination of the horseshoe contacts and discrete circuit boards for each target mounted to the bank of the bank are what is used to detect the three states of the drop target position.
 

[[File:WMS Drop Anim.GIF|150px|thumb|left|Simulation of the three different states of a Williams drop target]]
A simulation of the operation of a Williams drop target switch can be viewed at the animation located to the left. As mentioned before, the horseshoe contact is attached to the backside of the drop target plastic. The horseshoe contact makes physical contact with the thick copper or tinned traces of the circuit board, which is secured to the backside of the drop target bank. 

An explanation of the three different states of the drop target are:
#When the horseshoe contact is located at the uppermost set of traces, the first frame in the animation, the drop target is in the upright position (fully reset).
#Once the drop target face is struck by the ball, the drop target plastic is pushed from the metal ledge of the metal drop target frame. As the drop target falls, the horseshoe contacts slide over a second set of traces on the circuit board, as seen in the second frame of the animation. These contacts are tied to the switch matrix via a switch strobe and return line respectively. The switch strobe line is common to all drop targets in the bank, while each drop target in a bank will have its own switch return line. Each switch pair is used for scoring purposes.
#Finally, the drop target will fully drop, and the contacts come to rest on a third set of traces on the circuit board. This set of traces is tied in series from one drop target circuit board to the other. Because the pairs of traces for each target are tied together in series, a switch, secondary to the individual scoring switches is used. Once all of the targets in the bank are dropped, the series switch circuit is complete. The switch matrix detects this as a single switch closure. In turn, the drop target bank is reset.
 

[[File:WMS Horseshoe Drop Bank Marked.JPG|200px|thumb|left|Switch solder points identified on a drop target bank]] 
With the maze of similar-colored wires on the back of a Williams first generation drop target bank, it can be somewhat intimidating as to what wire goes where. The switch return lines (white wires with colored traces) attach to the solder tabs of the eyelets. Likewise, the non-banded side of the diode attaches to the same solder tab of the eyelet. The switch strobe line (green wire with a colored trace) can be attached to any of the points circled in green. On the bank in the adjacent pic, the switch strobe wire was attached to the green circled area on the far right. The black and gray wires are sometimes substituted with different colors like yellow.
 

===Second Generation Drop Target Bank===
[[File:WMS Leaf Drops.JPG|thumb|200px|left|Typical second generation Williams drop target bank]] 
Starting with Black Knight, Williams slightly changed the design of the drop target bank. Instead of using horseshoe contacts and circuit boards for switch detection on each drop target, the horseshoe contacts were replaced with a copper leaf spring and the discrete circuit boards were replaced with leaf switch stacks. Detecting when all the drop targets down was now handled via software. There are subtle physical differences in the drop target plastic. The most obvious difference is the thickness of the bottom of the drop target. The thickness was increased to compensate for the use of bottom mounted leaf switches.
 

===Third Generation Drop Target Bank===
+++ Need pic of drop target bank with microswitches +++ 
The third and final generation of System 3-7 drop target banks are essentially the same as the second generation. The main difference is that microswitches were used to detect when a drop target drops versus leaf switches.
 

==Additional Diagnostics - Pincoder test ROMs==
A comprehensive set of free, third party diagnostic/test ROMs can be found here: http://pincoder.ca

These ROMs can be used in-game to test individual components of your pinball machine. Additionally, the RAM and CMOS tests thoroughly check all addressable locations within each chip, resulting in extremely accurate results.

Support for these ROMs can be found on Pinside here: https://pinside.com/pinball/forum/topic/new-williams-system-6-in-game-test-roms

=Recommended Modifications=

==Additional Fuses==
[[File:WMS_Sys6_Fused_Bridges.JPG|left|thumb|300px|Fuse holders with 8 amp slo-blo fuses added to one of the AC inputs to each of the bridge rectifiers. (Firepower)]]
[[File:WMS 3-7 Fused Bridges Inline Butt Connectors.jpg|right|thumb|300px|Inline fuse holders installed with solderless crimp butt connectors]] 
Williams failed to include fuses in the AC connection between the transformer secondary and the solenoid and controlled lamp bridge rectifiers. In theory, the primary power fuse should blow if one of these bridges short. However, this is not always the case. Sometimes, the bridges short in such a manner that the wiring from the transformer secondary to the bridge becomes the fuse, and the wiring insulation melts until something gives.

This problem can be addressed by adding 2 fuse blocks and two 8 amp slo-blo fuses. For each bridge, afuse is added between either transformer secondary wire and the bridge. The AC inputs to the bridge are both marked with a 'tilde' on the BR which looks like an 'S' on it's side: '''~'''. The wire colors are typically red for solenoids, and blue for the controlled lamps. However, it is best to consult the game schematics to confirm.

Although the preferred method is to put fuse holders on the backbox wall, installing fuses in any configuration is paramount. One way is to use inline fuse holders, and solderless crimp butt connectors. This is a quick and easy alternative, even though it may not be the prettiest solution.
 

[[File:FirePowerAdditionalFusing.jpg|left|thumb|300px|The Firepower schematics, updated to include two 8ASB fuses between the transformer secondary and both the solenoid and controlled lamp bridge rectifiers.]] 
Williams incorporated an 8A normal-blo fuse in later games (Big Guns and newer), while Data East chose to install 8A slo-blo fuses.

A nice solution for this problem is the Inkochnito Bridge Board that can be found at this link: http://www.inkochnito.nl. Click on the Bridge Board image for more information.

System 3 and System 4 games did not incorporate a fuse for the 9.3VAC supply lines. If either diode D7 or D8 shorts, something in the circuit will act as a fuse. Sometimes, a board trace acts as a fuse under these conditions. It is much, much better to add two 4 amp slo-blo fuses directly after the transformer, just as Williams did when System 6 games were introduced.
 

==MPU Batteries & Memory==

===Relocating the batteries away from the MPU board===
[[File:Leaking_Battery.jpg|120px|thumb|left|Leaking Battery]]
Relocating the 3xAA batteries from the MPU board is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. Sometimes the battery terminals don't look corroded, but the metal rivet which contacts the battery are actually missing. 

If "04 00" is displayed in the credit/match display, rather than the game going into attract mode, then the game is in audits mode:
* The batteries have failed and need replacing
* The battery voltage is not reaching the 5101 CMOS RAM (check Test Point TP7, which should measure 4.3v with the power on and 3.9v (or so) with the power off.
* Blocking Diode D18 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There is another problem holding settings, such as a faulty 5101 CMOS RAM.

Simply removing the batteries is not really an option as the game will not boot directly into "attract mode" when switched on. It also will not retain the settings such as the number of balls per game, the free play setting (usually obtained by setting maximum credits to 0), or high scores It's possible on System 3-7 games to switch the game off, and then quickly back on to go from the '04 00 audit mode' to attract mode. Credits would still need to be added by the coin switches.
 

===Remote Battery Pack===

One option is to remotely locate the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) any circuit board (see driver board pic below). Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually.

Adding a connector between the battery pack and the MPU board is a good idea, so the pack can easily remove the battery pack from the board. Plus, it the batteries are forgotten and do leak, the MPU board will not have to be removed to add another battery pack. Another solution is to buy a battery holder with the 'transistor radio' type connector which can be snapped on and off. Just be very careful if using this style of connector. Adding a tag noting that a '''9 volt battery should never be connected''' is a very good idea. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is a available, a diode or jumper can be soldered in the first position. A diode is the preferred approach, as this will prevent the batteries from being charged and 'cooked' by the game if blocking diode D17 on the MPU board fails. Keep in mind that an added secondary diode to this circuit will decrease the voltage passing to the 5101, if D17 is still good. Locate a 1N4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the Red wire and towards the (+) terminal marking on the MPU board.

The game takes 3 x AA Batteries, so it uses at least 4.5v total. However, it will still store settings down to about 3v or so. After that an AA battery's life will taper off very quickly. A fresh set of batteries should last for at least a year, or the is some other issue. If the 5101 CMOS RAM is socketed, it's possible that it isn't the low power version. Or, possibly the D17 diode has shorted.

The images below illustrate how to install the wiring for battery packs on the different MPU Boards.

[[File:WMS_sys4_MPU_board.JPG|300px|thumb|left|Williams System 4 MPU Board]] 
On the System 4 MPU, solder the battery cables: Ground (Black Wire) to the Bottom Left pad and Positive (Red Wire) to the Top Right.
 

[[File:WMS_sys6a_MPU_board.JPG|300px|thumb|left|Williams System 6 MPU Board]] 
On the System 6(a) MPU, solder the battery cables: Ground (Black Wire) to the Top Right pad and Positive (Red Wire) to the Bottom Left.
 

[[File:WMS_sys7_MPU_board.JPG|300px|thumb|left|Williams System 7 MPU Board]] 
On the System 7 MPU, solder the battery cables: Ground (Black Wire) to the Bottom Left pad and Positive (Red Wire) to the Top Right.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the (+) and (-) pads of the MPU board. All battery packs are pretty cheaply made, and failures "out of the box" can be somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.

Another good practice, while the MPU board is already out, is to check the D17 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the 5101 non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. If Alkaline batteries are charged, they will be damaged and fail, leak, or (in extreme cases) explode. Testing the D17 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D17 diode with a 1N4148, or add a secondary 1N4004 to the battery pack. Once again, if a secondary diode is added, it will decrease the voltage passing to the 5101, if D17 is still good.

[[File:Wms drvr bat dam.JPG|300px|thumb|left|Alkaline Damaged Williams Driver Board]] 
It is important to remotely relocate the batteries from the MPU board, unless using a lithium replacement. The potential is there for not only the MPU to become damaged, but other associated boards in the backbox. The pic to the left is a prime example of extended damage. The damage occurred in this instance, because the shuffle bowler this board came from was stored with the batteries still on the MPU board for an extended period of time (roughly 5-8 years). It's a costly shame, because this was an otherwise decent, clean, working driver board. The amount of repairs which have to be performed now are going to be extensive.
 

===Installing a Lithium Coin Cell Battery Backup===
An alternate solution to a remotely located battery pack is to use a single CR2032 battery and holder mounted on the MPU. Lithium button batteries do leak, although not nearly as commonly or as severe as alkaline batteries. And, since the battery will be contained in a holder mounted above the PCB, there is little risk of corrosion attacking the board.

The holder and replacement batteries are inexpensive. 
The following photo gallery shows the installation procedure. 
This method can be adapted to work with all Williams System 3-7 MPU board.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Williams System 4 MPU Coin Cell Installation">
File:System4MPUCoinCell-1.jpg |<center>Small hole drilled at intersection of holder pin "arc" and trace on board solder side.</center>
File:System4MPUCoinCell-2.jpg |<center>Battery holder installed, front side. Note the "zero ohm jumper" soldered between the top left and top right battery holder holes.</center>
File:System4MPUCoinCell-3.jpg |<center>Battery holder installed, rear side. Note the negative connection marked lower right and the path of the positive connection.</center>
</gallery>
</center>
 

===Installing a Memory Capacitor (SuperCap) Instead of Batteries===
Another alternative is to install a memory capacitor. In essence, a memory capacitor is similar to a rechargeable battery, although, the likelihood of a memory capacitor leaking is minimal compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off, the memory capacitor slowly loses its charge over time. Therefore, it is imperative that the game periodically be turned on to allow the capacitor to charge up to its full capacity again. If a game will not be turned on for long lengths of time, a memory capacitor may not be the best solution.
 

====System 3/4====
[[File:System3-4SuperCap.jpg|300px|thumb|left|5.5V 1F Memory Capacitor Added to a System 3 MPU Board.]] 
When installing a SuperCap, the polarity of the cap needs to match the battery pad polarity. Connect the negative lead of the cap to ground. In the picture at left, the old top center battery holder connection was leveraged as an attach point. A jumper (not shown) on the back of the board connects from there to the edge of board ground.

Connect the positive lead to the the upper right battery holder connection through hole.

Remove D18 and replace with a 100ohm 1/4W resistor.

Once the capacitor is installed, and the board installed back in the game, leave the game powered on to allow the game to charge the capacitor fully. After that, turning the game on monthly for about 10 minutes allows the capacitor to recharge.

 

====System 6====
[[File:WMS Sys6 Mem Cap.JPG|300px|thumb|left|5.5V 1.5F Memory Capacitor Added to a System 6 MPU Board. Labels added to help locate parts.]] 
When installing a SuperCap, the polarity of the cap needs to match the battery pad polarity. Connect the negative lead of the cap to ground. Connect the positive lead to the banded side of diode D18 (1N5817). The picture to the left shows a jumper added to connect the negative lead of the cap to ground on a System 6 MPU board.

As an alternative to running the positive lead of the cap to diode D18, the positive cap lead is installed in the positive battery terminal. The diode at D17 (1N4148) is removed, and a 100ohm resistor (or similar value) replaces the diode. Adding a resistor in place of D17 allows the game to charge the capacitor. Once the capacitor is installed, and the board installed back in the game, leave the game powered on to allow the game to charge the capacitor fully. After that, turning the game on monthly for about 10 minutes allows the capacitor to recharge. If the cap is losing its charge rapidly, diode D18 may be faulty, and should be replaced.
 

====System 7====
Follow these steps to add a SuperCap to a System 7 MPU.
#Drill a 1/16" hole NorthWest of the upper right positive battery terminal solder pad. The distance from the positive battery terminal hole should be the width of the SuperCap leads. The hole will be pierce a large ground trace on the solder side of the board (right hand image).
#Solder the SuperCap positive lead through the battery terminal solder pad.
#Solder the SuperCap negative lead to the ground trace on the solder side of the board.
#Remove diode D17, a 1N4148.
#Install a 100ohm (or thereabouts) 1/4W resistor in place of D17. Polarity is not important as resistors have no polarity.

The following images demonstrate the procedure.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Williams System 7 MPU SuperCap Installation">
File:WMSSystem7SuperCap-1.jpg|<center>1/16" hole drilled for the negative "leg" of the SuperCap.</center>
File:WMSSystem7SuperCap-2.jpg|<center>The SuperCap and 100ohm resistor installed.</center>
File:WMSSystem7SuperCap-3.jpg|<center>The solder side of the board showing SuperCap connections.</center>
</gallery>
</center>
 

===Installing NVRAM ===

NVRAM (non-volatile RAM) can be used in all Williams System 3 through 7 MPUs. By installing NVRAM, batteries will never, ever, be required to retain game settings and high scores. The possibility of spewing alkaline onto the board is eliminated.

For System 3-7 games, the 5101 RAM chip is always at IC19, although the actual physical position of IC19 on the MPU differs between the systems. Unfortunately, the 5101 RAM is '''always''' soldered directly onto the board. It must be desoldered and replaced with a 22-pin 0.3" width socket to accommodate the NVRAM.

NVRAM are discussed [http://www.pinwiki.com/wiki/index.php?title=MPU_Battery_Replacement_Options#Products here].

==Improving the Early System 3 Flipper Response==

For the early solid state games, Williams re-used the flipper mechanism from their electromechanical games. This design, composed of multiple pieces screwed to the bottom of the playfield, is functional but somewhat clunky in operation. There are those that advocate scrapping the mechanism and replacing it with modern Williams baseplate design flippers. While this certainly works, and provides a much nicer flipper response, it also costs money for new parts when the old parts can be made to work reasonably well.

First, rebuild the flipper assembly with fresh parts. This includes the coil stops, plunger and links, coil sleeves, EOS switches, cabinet switches, and pawls (if needed). Pinball Resource has all these parts.

This leaves a functional, reasonably strong, but 'clunky' flipper. It will work, but it will not seem as 'snappy' and 'fast' as a modern game. While the modern (WPC) baseplate style flipper mechanism is nice, the most important change is actually not the baseplate, it is the modern flipper bat itself.

There is a slight difference in mass between the original bat at 1.5 oz and the new bat at a little under 1 oz, but what accounts for the difference is the way the mass is distributed. On the old flipper design, a heavy metal base is welded to the shaft, and the plastic bat is screwed to the base. On the new design, the plastic bat is simply molded to the shaft, eliminating the base entirely.

<center>
<gallery widths=300px heights=300px perrow=2 caption="Williams Flipper Bat Comparison">
File:s3fbat1.jpg|<center>Williams System 3 flipper bat assembly (two-piece)</center>
File:s3fbat4.jpg|<center>Williams molded flipper bat assembly</center>
</gallery>
</center>

When the flipper coil is energized, it begins accelerating the plunger, pulling it in to the centre of the coil. This acceleration is transmitted to the shaft via the crank, accelerating the flipper bat. In this rotational acceleration of the bat, the further the mass is from the centre of the shaft, the more work required to accelerate it, and the slower the rate of acceleration. (Incidentally, this is why magnesium wheels first became popular in drag racing; they are lighter than steel wheels and increase the car's rate of acceleration. It does not change the car's top speed, but it does reduce the time it takes the car to reach top speed, making it quicker.)

At the end of the coil's power stroke, the plunger slams in to the coil stop, rapidly decelerating. In turn, then, the link, crank, and flipper bat also slam in to the previous part and rapidly decelerate. In this part of the action, the higher mass of the old flipper bat has more momentum, and due to the location of that mass, has more leverage to apply the force of the momentum. This leads to a hard clunk as all of that mass slams to a stop, and often results in a flipper bat that 'bounces' at the end of stroke.

The solution to both of these is to reduce the mass of the flipper bat, especially reducing it as far from the centre line of the flipper shaft as possible. Looking at the options, there are only three pieces to the flipper bat. The plastic bat is not really easily modified to reduce any serious mass. The screw that holds the plastic bat to the base is not easy to reduce in mass, and being located close to the centre line of the flipper shaft, it has very little effect on the operation. That leaves the flipper shaft and its welded on base.

The shaft itself has significant mass, but the mass of the shaft is located very close to the centre line, so it can be ignored as well. That, then, leaves the base. Here there is quite a lot of mass, and much of it is located a good distance from the centre line of the flipper shaft.

First remove the plastic shoe from the bat (there is a single screw underneath the bat). Then screw the metal bat to a piece of scrap wood, and drill the metal bat baseplate to remove metal. This is easiest to do neatly with a drill press. Drill two 5/16" hole near the shaft, and progressively smaller holes toward the tip. A total of seven holes can be drilled: 5/16", 5/16", 1/4", 7/32", 3/16", 5/32", 1/8". These holes remove about 1/2 oz from the flipper bat assembly without significantly affecting its strength or durability.

<center>
<gallery widths=300px heights=300px perrow=2 caption="System 3 Flipper Bat Modification">
File:s3fbat2.jpg|<center>Drilling the flipper bat shoe</center>
File:s3fbat3.jpg|<center>Flipper bat shoe after being drilled</center>
</gallery>
</center>

Reassemble the flipper bat, install, and enjoy. The flippers should feel snappier.

=Problems and Fixes=

== Cross Connecting Black and White Backbox Connectors ==
[[File:WMSSystem7PharoahConnectors.jpg|300px|thumb|left|The infamous System 7/9 connectors that can be cross connected. Yikes!]]
[[File:FirePowerCrossConnect.jpg ‎|300px|thumb|right|These two FirePower connectors are clearly misconnected as can be seen by different wire colors entering and leaving the connector pair. The connector colors should not be trusted. Image courtesy of Kevin Scholbe.]] 
In one of the biggest mistakes in pinball manufacturing, Williams used two identical 24 pin .062 connectors to connect cabinet and backbox wiring. The connectors are identical with the exception that one is black and one is white. During manufacturing, the wrong color connector was sometimes used. Bottom line: do not simply mate black to black and white to white. Instead, ensure that the wire colors going into one side of the connector are the same as the wire colors coming out the other side. This is the only foolproof method of avoiding the catastrophe of cross connecting circuits, causing certain damage to the MPU and/or driver board.
 

==Advanced Diagnostic Tool by Pincoder==

An advanced diagnostic tool with full (downloadable) documentation and active support is available here: [https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/ Pincoder Adapter]. The Adapter simply plugs into the MPU board right out of the box and can be used in-game for all tests.

==Built In Diagnostics==
[[File:WMSSystem3DiagnosticButtonCropped.jpg|300px|thumb|left|Diagnostic switch location on a WMS System 3 MPU]]The built in diagnostics of the Williams System 3 - 7 board set are extremely limited. The board set either powers up or it doesn't.

There are two diagnostic LEDs on the MPU (system 7 MPUs feature a 7 segment display). However, the usefulness of these LEDs is at best limited and generally just confusing. A properly booting System 3-6 game will flash both LEDs once, and then the LEDs will remain off. This flash is a bit longer than a flicker, staying on for about 1/2 second. A properly booting System 7 game will flash a zero on the 7 segment display. The 7 segment display will then go blank.

Pressing the Diagnostic button on a properly functioning System 3 - 6 MPU will cause both LEDs to flash twice in unison and then go off. If the bottom LED remains on, the game software is indicating a ROM failure. If the top LED remains on, the game software is indicating a RAM failure (6810). And if both LEDs remain on, the game software is indicating a CMOS RAM failure (5101). However, the accuracy of this test is questionable since the game software must be functioning properly for the test report to be valid and the game software requires ROM and RAM to function in the first place. The short advice is: don't rely on this diagnostic test result.
 

Pressing the Diagnostic button on a properly functioning System 7 MPU will cause the 7 segment display to flash a zero and then go blank. System 7 diagnostics are a bit more useful than prior Williams game systems but are still not 100% trustworthy. If the MPU built-in-test software detects a problem with the game hardware, the 7 segment display will remain on with an error code displayed. Possible error codes are:

*0 - and then goes out...all tests passed
*1 - IC13 RAM or IC20 ROM failed
*2 - IC16 RAM failure
*3 - IC17 ROM failure
*4 - IC17 ROM failure (duplicated test...yes)
*5 - IC20 ROM failure or the coin door was closed or memory protect fault
*6 - IC14 Game ROM failure
*7 - IC26 Game ROM failure
*8 - IC19 (5101) RAM failure or the coin door was closed or memory protect fault
*9 - IC19 (5101 again) RAM failure or the coin door was closed or memory protect fault

'''To test displays, lamps, coils and switches for System 3 and 4 games, follow this procedure first, then proceed to the System 6-7 procedure below .''' 

Entering the familiar diagnostic mode of later game systems is a bit less intuitive with a System 3 or 4 game. To enter diagnostics, press the diagnostic button on the MPU once. This is the lower of the two buttons as pictured at left. Both LEDs should flash and all displays will go blank. At this point, the game is ready to accept new game settings like "balls per play" via the obtuse and ridiculous to use dip switches on the MPU. Skipping over the process that essentially amounts to "memory pokes" (who remembers that), the diagnostics can now be controlled from the front door switches. If the AUTO/MANUAL switch is in the MANUAL position, pressing the ADVANCE button will cause each score display to show all zeros. The next press will show all ones, etc. If the AUTO/MANUAL switch is in the AUTO position, pressing the ADVANCE button will cause the score displays to begin cycling, starting with all zeros, then all ones, etc.

[[File:YT.png]] A video demonstrating System 3 and 4 game diagnostic entry can be found [https://youtu.be/Bq7Bubb5X6w here].

[[File:WMSSystem3-7CoinDoorSwitches.jpg|300px|thumb|left|Williams System 3 - 7 Coin Door Switches]]
'''For System 6-7 games, follow this procedure to test displays, lamps, coils and switches.''' 

With the AUTO/MANUAL switch in the MANUAL position, press the ADVANCE button. This will cause each score display to show all zeros. Pressing the ADVANCE button again will display all ones, etc. If the AUTO/MANUAL switch is moved to the AUTO position, the score displays will advance automatically through each of the digits (zero through 9).

With the AUTO/MANUAL switch still in the AUTO position, press the ADVANCE button to advance to the next test. The match portion of the credit/match display will show "01" and all playfield lamps will begin to cycle on/off.

Pressing ADVANCE again will display "02" in the match window, and the game will begin an ordered activation of each coil in sequence (including buzzers, flashers, etc).

Pressing ADVANCE again will display "03" in the match window. This is "switch test" mode. If no switches are closed, the credit half of the credit/match window will be blank. Closing a switch will result in the switch number being displayed in the credit window. If more than one switch is closed when switch test begins, the number of each switch will be displayed once in the credit window. After that point, only closing a switch will cause it's number to be displayed. i.e. switch test does not cycle through all closed switches but instead displays ONLY the last switch closure detected (at least in System 3 games).

Pressing the ADVANCE button one more time displays "04" in the match window, and game status information is displayed in sequence, automatically for system 3 and 4 games and by pressing the advance button for system 6 and 7 games.
 

== Quick Start: Repairing a Williams System 3-7 MPU ==

The procedure for repairing a Williams MPU is outlined below. More detail can be found later in this document.

<ol>
<li>Replace the power header at 1J2, which is located on the left side of the MPU. The cornerstone of a well running MPU is clean, consistent power. Tarnished connections, worn connections that have exceeded the mate cycle spec, and cracked header pin solder joints all negatively impact power.</li>
<li>If the OEM chip sockets are still on the board, replace them with quality twin leaf or machine pin sockets. Good chip sockets will ensure rock solid connections between the ICs and the various busses. Always replace Scanbe and white Molex sockets - no exceptions!</li>

[[File:OEMROMs.jpg|300px|thumb|right|The ROM on the right in this picture has obviously been heat stressed.]]

<li>Examine the 40-pin male connector closely. If it exhibits any of the following characteristics, replace it.
*Tarnished pins
*Corroded pins (due to batteries on the MPU leaking corrosive alkaline)
*Fractured solder joints
*Solder joint “craters”, i.e. an attempt to “reflow” the solder joint that doesn’t adhere to the pin very well. The solder surrounds the pins, but does not create a solid electrical connection to the pins.
</li>

<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>
<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>
<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect.</li>
<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>
<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>
<li>Make certain the blanking signal goes high and remains high almost immediately after successful MPU boot. The blanking signal is easily tested at pin 37 of the 40-pin interconnect board.</li>
<li>Install Leon’s test ROM to verify processor, PIA, and memory operation.</li>
</ol>

===Further Recommended Reliability Improvements===

#Replace all headers. Reflowing solder does not create a solid mechanical or electrical connection.
#Replace masked ROMs with new ROMs.
#Update the MPU to use fewer sockets. i.e. use a 2716 (or double the image into a 2732) at IC14.
#Move the backup battery to a remote location or install NVRAM. Batteries should be removed from the MPU board as soon as possible.

===Adding System 3-6-like Diagnostic LEDs to a System 7 MPU===
[[File:System7DiagnosticLEDAddition.jpg|300px|thumb|left|Diagram depicting addition of 2 LEDs and 2 resistors that provide the same function as System 3-6 MPU boards]]
[[File:System7FactoryLEDs.jpg|300px|thumb|right|A System 7 MPU with factory installed diagnostic LEDs]] 
System 7 MPUs replaced the two diagnostic LEDs of past systems with a 7-Segment LED display to provide diagnostic indications. At times, the 7447 driver IC or the 7-segment LED display itself can fail. Or perhaps running system 3-6 software in the board, while retaining the LED diagnostic capability, is the objective.

Rather than replacing the 7-Segment display or 7447, adding System 3-7-like LEDs to the MPU is easy. Procure 2 standard LEDs and two 1/4 watt resistors of any value between 100 ohms and 560 ohms. Incrementally higher ohm resistors will dim the LEDs incrementally, but can still be used.

Add two resistors on the right-most pads as pictured at left. 
Add two LEDs to the top two available pads as pictured at left, with the "flat side" (the short leg or anode) oriented toward the 7-segment display. It's as easy as that.
 

==Quick Start: Repairing a Williams System 3-7 Driver Board==

The detailed procedures for repairing a Williams driver board can be found later in this document.

<ol>
<li>Replace the 40-pin female interconnect. Due to fatigue and/or battery damage (alkaline corrosion), this connector can and will become unreliable over time. Replace it.</li>
<li>Remove and reflow the solder on *all* of the header pin connectors. Another choice is to replace the connectors with new ones.</li>
<li>Replace all suspect chip sockets. PIAs on the driver board were the only chips socketed from the factory on this board. However, the factory used crappy Scanbe sockets for these chips. If Scanbe sockets are present, replace them.</li>
<li>Inspect the PIA chips. If AMI chips were used, suspect eventual, premature failure. Replace if possible.</li>
<li>If the factory 3 watt current limiting resistors in the lamp matrix appear heat damaged, replace them with 27 ohm 5 watt resistors. "Sand" resistors are a good replacement choice.</li>
<li>If heavy heat damage is present in the vicinity of the lamp matrix power resistors, suspect potential failure of the lamp matrix ICs (IC13 & IC14) located just above the resistors.</li>
</ol>

==Using a PC Power Supply For Bench Testing==
Sometimes it is more beneficial to do testing / troubleshooting while the MPU and / or driver boards are outside of the game. It's unfortunate, but the System 3-7 boards were designed in such a way that both the MPU and driver board have to be attached to one another for the MPU to effectively boot and function. Since the driver board has no intelligence located on it, it needs to be connected to the MPU to be of any use. 

[[File:WMS Sys6 On Bench.JPG|300px|thumb|left|WMS System 6 MPU and Driver Board Powered by a PC Power Supply. Power connections are attached to the readily available test points on the MPU board.]]
[[File:WMS Sys7 Bench Power.JPG|300px|thumb|right|WMS System 7 MPU and Driver Board Powered by a PC Power Supply. Power connections are attached to IJ2 on the MPU board.]]
The voltages needed to power a System 3-7 board pair on the bench are +5v, +12v, and ground. Connections can be made to the appropriate pins on 1J2 (only header connection on left side of MPU board). The connections are as follows:

*Pins 1-3 (ground)
*Pins 4- 6 (+5 volts)
*Pin 9 (+12 volts)

If connecting a '''System 6 or 7 board pair''', it is easier to connect to the test points. The connections are as follows:

*Test point 1 (+12 volts)
*Test point 9 (+5 volts)
*Test point 10 (ground)

Note that test points 9 and 10 have different locations between a System 6 and 7 MPU board.
 

== Connecting a Logic Probe to the Williams System 3-7 MPU ==

[[File:WMSSystem3LogicProbeConnection.jpg|300px|thumb|left|Connecting a logic probe to a System 3-7 MPU. This picture is a System 3 MPU.]]
[[File:WMSSystem6LogicProbeConnection.jpg|300px|thumb|right|An alternate method to connect a logic probe on a System 6/6A MPU.]] 
The easiest way to power the logic probe is across the input power's electrolytic filter cap, as shown on this Williams System 3 board at left.
All MPUs, including Systems 3, 4, 6, 6A, and 7, feature this cap.

Since the MPU and driver board logic are electrically connected and powered by the same source, connecting the probe to the MPU allows probing driver board logic also.
 

==Connectors, connectors, connectors==

[[File:Wms cracked solder joints.JPG|thumb|left|300px|Cracked solder joints on the header pins of a Williams driver board]] 
With this era of game, most of them 30+ years old now, and they will have problems with connectors. One of the most common issues is cracked solder joints on header pin connections to the PCBs. Some cracks are more obvious than others, while some can only be seen clearly under proper magnification.
 

[[File:Wms header solder removed.JPG|thumb|left|300px|Solder removed from the header pins of a Williams driver board]] 
Although it can be somewhat time consuming and a tedious chore, it is best to remove the old solder from a header pin joint, and then add new, fresh solder. Performing this procedure is a necessity on these games to ensure reliability. The other option is removing the header pin connection completely, and replace with a new one.
 

If the game starts to reset for no reason during play, or when both flippers are engaged, it may be worth first re-pinning the connectors at 1J2 on the MPU Board and at the outputs from the PSU. This is always a good step even if it does not fix the immediate issue, as it avoids power problems later on. 

This will involves replacing the header pins on the PSU board and the female connectors on the cables. The pins are .156" and square pins are preferred, although round are still available. Use phosphor bronze. On the female side, crimp pins of the trifuricon type are best.

Second prize goes to reflowing solder to the back of the header pins, and just replacing the female IDC connectors with new ones. In that case rather than a crimper, the .156" 'punch-down' tool '''''must''''' be used for this replacement to work correctly. If the correct tool is not used, the IDC housing and pins will be damaged, especially if a screwdriver or some other makeshift tool is used. After that, the wires just don't seat correctly and will not maintain proper contact. Always cut back to clean wire and punch down correctly to a new IDC connector, reusing an old one rarely works.

Again, the connector is a .156" 9-way connector at 1J2. There is also a 'key' pin where the hole is blanked off on the connectors and the pin cut off flush with the board. This prevents plugging the power in to say the switch matrix or swapping two connectors over. It's easiest to just buy a bag of these for blanking off the 'key' positions, rather than try to re-use old ones.

==Wiring Connector Issues==
[[File:WMSSystem7BlownICs.jpg|300px|thumb|left|Socketed and replaced ICs blown by incorrect connector hookup.]] 
Williams made a poor wiring harness design decision with this series of games that allows the cabinet harness to be connected to the head harness (36 pin inline connectors). Mating these connectors incorrectly will short the 28V solenoid circuit to the logic voltage level circuit, destroying ICs on the MPU and perhaps the driver board. Always be sure to double check connector pin counts and colors, but most importantly, wire colors going into and out of both sides of the connector. Connector color is not a 100% reliable indicator as Williams sometimes used white connectors, sometimes used black connectors for both, and sometimes may even have used one black and one white connector. Wire colors should always match up.

A real world example on a System 7 Jungle Lord, pictured at left, resulted in MPU IC7 (7404), IC32 (7400), and IC12 (7408) being blown. The 5101 wasn't destroyed. On the driver board, IC16 (7406) was also damaged. The amount of damage can vary, however, other instances suggest a similar path of destruction. The best course of action should this occur is to spend a lot of time with a DMM in diode test, checking each individual IC. Socketed ICs, like the 5101 and the 6808/2 can be easily tested in a known working system.

 

==System 7 MPU Board Issues ==
Diagnostics, and the 'System 7 MPU Board won't boot'.

Forget about getting anything at all on the Player Displays without having working ROMs in place and a good MPU board. Blanking has to go 'high' before the displays will work. So coin door game diagnostics are useless until the MPU board runs correctly.

But help is at hand on the System 7 MPU, Williams added a single 7 segment LED display to the board. To get anything at all on the 7 segment display LED on the MPU, these conditions must be met:
* The 74LS47 Display Driver IC34 to be working.
* The 6821 PIA (at IC18) on the MPU responsible for driving the score displays to be working.
* The logic +5v to be good.

Normally when a properly functioning board boots, the 7 segment LED display will flash "0" briefly and then the display is turned off, and remains off. If within a game, the game would then be in attract mode if everything was perfect. Pressing diagnostics should show a "0" and then return to attract mode with the LED display blank. [ed Note: Correct me if that is wrong]

Once the above-mentioned chips are installed and working and the sockets have been replaced or tested good:
* With no ROMs installed, a board with a fault or a ROM fault if they are installed, the "top two" LEDs (if there) would be lit and the LED display would show "0". The MPU board is 'locked up', in that condition.
* Display Driver PIA IC PA4 - PA7 will be high. Pressing the * Diagnostic switch will not change things.

Then an OS is needed, which is the 'Flipper ROMs' in pinball.
When they 'Boot' (provide a set of instructions to the CPU)- even with the Game ROM removed, the fist thing they do is to "turn off" the LEDs 1+2 and so the onboard LED display (7447) would then go blank.

In fact, "0" should flash once and go blank. That means the board is not locked and at least booted the OS.

Installing a good Game ROM after that may provide access to the diagnostics if everything is working up to this point. Pressing the diagnostic switch should then provide a (hopefully) valid indication of what component is stopping the (pinball or whatever) from running. Here are the key indications (for System 7, Sys 8&9 may be similar):

These results can appear with error conditions by using the Flipper and Game ROMs, or the 2532 WMS Test ROM in IC17 (on Sys 7 boards):
If all the support chips are good, and one "0" flash appears and then goes blank, then the on-board error display can be trusted.

: '''Press the diagnostic button, the numbers are:'''
{| class="wikitable"
!colspan="2" |System 7 LED Diagnostics
|-
!Number
!Meaning
|-
|0 || Test Passed (only if display goes blank)
|-
|1 || IC13 RAM Faulty
|-
|2 || IC16 RAM Faulty
|-
|3 || IC17 ROM 2 Faulty
|-
|4 || IC17 ROM 2 Faulty
|-
|5 || IC20 ROM I Faulty
|-
|6 || IC14 Game ROM 1 Faulty
|-
|7 || IC26 Game ROM 0 Faulty
|-
|8 || IC19 CMOS RAM or memory protect circuit faulty
|-
|9 || Coin-door closed, memory protect circuit faulty, or IC19 CMOS RAM Faulty.
|}

Getting a 0 and remaining on could potentially be that the CPU / board has not successfully reset. In other words, no instructions have been passed to and from the CPU chip. This problem could be due to a faulty reset circuit. The lack of +12v on the MPU board can cause this too. 

Getting an 8 or 9 is *good* indication - it means the board is almost there!

Here are some further tips about those conditions:

8 - MPU board may be good. Is it looking for the Driver Board? (Like the missing 7th flash on a Bally MPU).

Make sure the Driver Board is connected and the "40-way" interconnect has continuity on all pins.
From System 8 on there is no interconnect... so by System 9 MPU and Driverboard (and Sound!) are all one PCB.

Then suspect that IC19 RAM is faulty or finally a memory protect fault.

9 - First check for coin door closed (or pin 1J4-1 or 1J3-1 is being grounded), then is IC7 faulty? Finally is IC19 RAM faulty?

If a "9" is displayed, it may be tempting to install it in a game, open the coin door, and try and boot up. But this is wrong, as there still is a problem on the board. Either the IC19 5101 CMOS Ram is faulty, or another memory protect component is faulty.

Remember to do the "switch on, off and back on again quick" trick to see attract mode appears when reinstalling in a game after taking an MPU out. Many times, that does the trick. Also, if removing the Driver Board and reinserting it on the MPU board 'fixes' the problems and the boards will then boot correctly, then it points to the "40-way" connector needing to be replaced. Both header pins on the MPU and sockets on the Driver Board.

Parts: 

The 7-Segment display can be replaced with a KINGBRIGHT SA03-12HDB LED 0.3" RED DISPLAY. 
5101 CMOS RAM. 5101-1 The low power version is needed, as it needs battery backup to hold RAM contents when the game is powered off. 
A 6821 PIA is a standard part. MC6821 MC68B21 are common. The 6820 designation is much earlier but also works. Other designations:

xx6821, xx68A21, xx68B21, where xx can be MC (Motorola) or HD (Hitachi Data) will all work. The 'A' in 68A21 means the PIA will run at up to a 1.5Mhz Clock , the 'B' in 68B21 means up to a 2Mhz clock, without any letter is up to 1MHz. Any final letter is Package type (P,S or L) P=Plastic S=Cerdip and L=Ceramic. Any of the above speeds or package types will work for this era of pinball, so the letters can be ignored and any 6820 or 6821 can be used.

==Chip Sockets==
Reliable socket connections are a requirement for any printed circuit board to work as designed. Old sockets, as discussed below, should be replaced. Use extreme care in desoldering the old sockets, the traces and pads on circuit boards are easily lifted, especially if any battery corrosion is in the area. 

The chip sockets on old Williams boards (also most any board of this era) are long past their reliable lifetimes. They may work, but they may also cause intermittent connections that will have you chasing your tail tracking down odd problems with the game. Like the 40-pin interconnect used in Williams System 3-7 games, these sockets should always be replaced. 

Perhaps the most maligned socket brand, and rightfully so, is the Scanbe brand. In the picture below, it can be seen why. These 30+ year old sockets passed the point of reliability many years ago. Included in the Scanbe socket picture below are two pins pulled from a Scanbe socket. The pins were designed to grip the SIDES of the IC legs, unlike the design of modern sockets that grip the front and back faces of the IC leg. Get rid of them now. 

Later, WMS switched to sockets made by Augat or Raychem (all Tyco now). They occasionally go bad, but they can usually be left alone. But there is another type made by Molex which should also be replaced if it is found on a PCB. When looking at the picture below, it can be seen why. Curvy isn't it? And the contacts break easily too. Not as bad as the Scanbe but not much better either.
 

<center>
<gallery widths=200px heights=200px perrow=5 caption="Poor quality and old sockets found on many early pinball machine circuit boards">
File:WMS Speech Scanbe Socket.JPG|<center>It's hard to believe that these sockets ever worked.</center>
File:WMS Scanbe Removal.JPG|<center>A Scanbe socket being removed from circuit board by gently prying it up.</center>
File:ScanbeSocket.jpg|<center>Closeup of the infamous "Scanbe" brand socket. "Scanbe" is molded into the top of the socket face.</center>
File:ScanBeSocketPins.jpg ‎|<center>Closeup of "Scanbe" socket pins. Surface contact area was small from the factory.</center>
File:WMSMolexSocket.jpg|<center>Another bad socket type usually found in system 7 pcbs. This one was made by Molex.</center>
</gallery>
</center>
 

==Voltages==
The MPU board needs two voltages to boot: +12v which only the MPU uses for the reset circuit, and +5v (logic power) for the MPU and Driverboard IC chips.

If the game goes dead, but the sound board continues to work then there may be a fault with the PSU, power connections to the MPU, blanking or the reset circuit.

Check for sounds by pressing the sound board diagnostic test. The game will need to bed switched off & back on to cancel the looping sound test. The sound board has its own PSU. It takes 18v AC directly from the transformer and makes +12v (reset) +5v ( logic) and also -12v (Speech and mixers). It's probably OK to assume the +5v and +12v going to the MPU (and Driver Board) are OK from the PSU if the sound board boots and runs. It's like a mini MPU, with the same CPU and one PIA chip.

The main PSU board only needs to make the first two, +12v and +5v (no -12v) for the MPU and Driver board. But it also generates DC power for the flippers and the solenoids (+28v DC or so).

==Power Supply Issues==
The key thing to remember is that the PSU board is made up of separate output circuits combined on one board. They don't interact, and are in order:
* +18v for Lamps,
* +28v Solenoids (and Flippers),
* Regulated +5v for logic B+ and an unregulated +12v for CPU reset,
* +/- 100v HV supply for the Displays.

We're not counting the G.I. (General Illumination) circuit as it is AC only and is fused on the fuse card below the PSU. It only passes through the PSU board to be fused and controlled with a relay starting from System 7 games.

Input AC power gets to the PSU board directly from the transformer for the +5v/+12v and the display voltages.
However, in the case of the Lamp and Solenoid voltages AC is 'full wave' rectified (to DC) ''before reaching the PSU board''. This is done using two Bridge Rectifiers BR1 for Lamps (to the Right of the backbox) and BR2 for Solenoids and Flippers (to the Left of the backbox).

'''Lamp Voltage Supplies:'''
* The +18v DC Lamp voltage passes through a very large 'blue can' filter capacitor between the BR and the PSU board. This 'smooths out the 'bumps' (called AC ripple ) in the DC waveform.
** Because the MPU Controlled Lamps (for the inserts) are strobed by the Lamp Matrix, the resultant voltage to the bulbs is "averaged down" to about 6v DC.
*** Lamps are rated at 6.3v and 250mA for #44 Bulbs (so 1/4 Amp) or 150mA for #47 Bulbs (about 1/7 of an Amp).
*** Because they use less power, #47 bulbs will generate less heat.
*** Replace any shiny 'silvered' bulbs and any that say 0.3A as they burn way too hot and will ruin inserts and cause paint to flake on your backglass!
** '''Note:''' This has nothing to do with the G.I. (General Illumination circuit) which is fused on a fuse card and reaches to G.I. bulbs as about 6.3v AC.
*** As they (almost) always stay lit, the G.I. bulbs tend to last longer running on an AC voltage.
*** The AC is 'Tee-d' off to the cabinet, playfield and the insert board (for the backglass lighting).
*** Wire colors for G.I. (and must be measured as AC) are Yellow and Yellow/White.

'''Flipper and Solenoid Voltage Supplies:'''
* The +28v DC Solenoid voltage passes straight through to the PSU where it is fused before leaving on the way to the playfield.
** There are some additional components (a varistor and some filter capacitors) on the PSU board for the Solenoid/Flipper power.

'''Connectors on the PSU Board'''
* All AC voltages come into the PSU board in the large 12-way connector 3J1, while the black ground wires are on the 6-way 3J2.
**The fused '''''AC and DC''''' voltages exit on the larger of the 'D' shaped connectors, while the black Lamp and solenoid ground wires exit on the smaller of the 'D' connectors.

'''+5v Logic and +12v Unregulated Supplies:'''
*In the case of the +12v (and +5v a logic power), the AC comes into the PSU board at 3J1-10 11&12 directly from the transformer windings.
** You can measure about 10v AC in at the bottom of the diodes D7 and D8 with respect to the board's ground.
*** The total AC input is 18.6v, so each diode 'sees' 9.3v because the transformer winding 'center tap' at 3J1-12 is grounded.
*** D7 connects to 3J1-10, and D8 to 3J1-11 and you would trace connections from there back to the transformer.
*** If you measure AC across the bottom of these two diodes you should see the full 18.6v AC.
*** Do not worry if this AC value is higher without a load, it can (and will) vary with changes in line voltages.
*** Values over 20v AC are considered normal without a load. ''It's a 'schoolboy error' to chase the voltages of unregulated supplies trying to get them to be exact.'' This includes the AC input and +12v DC unregulated supply.
** The two large diodes at D7/D8 rectify the voltage to around +12v DC, again this is unregulated.
*** It is filtered by a large capacitor (12,000 uF or higher) to smooth out the AC ripple.
*** It is fused at 4A Slo-Blow, before exiting at 3J6-6 as the +12v DC for the reset circuit on the MPU Board.

* To generate the regulated +5v logic supply
** The +12v input is filtered more by capacitor C16 and then passed through X3 which is a +5v voltage regulator.
** This exits at 3J5-6 as exactly +5v for the Master Display Board ICs and at 3J6-7 to 3J6-10 for the other +5v supplies (MPU and Driver Boards).

''Please note that the Sound Board generates its own +12v and regulated +5v supplies for both Sound and Speech Boards. This is discussed in the [[Williams_System_3_-_7#Sound_.2F_Speech_Board_Issues | Sound & Speech Board Repair]] Section.''

===General Illumination Connection Design Flaws===
Starting with System 7 games, the general illumination passed through the power supply. This was done to turn the general illumination off (for effect) via a newly added relay on the power supply board. Unfortunately, Williams did not spec connections which could properly handle the current used for the general illumination. The end result was connections, whether it be housings or header pins, which became hot and / or burnt. As the connections tarnish, resistance increases, and the connections become hotter. The cycle continues until an inline fuse blows, or in most cases, discontinuity in the circuit occurs.

The only option is to purchase the proper Molex housing and pins and replace both the male and female connections. Replacing one side but not the other is futile. The issue will reoccur at a much faster rate than replacing both sides. Another preventative measure is to reduce the amount of current draw by replacing the lamps with LEDs. LEDs draw less current than 44, 47, and 555 bulbs, and the GI connections become less of an issue in the future when LEDs are installed.

===+/-100v Display HV Section of PSU===
Here is a document for troubleshooting and repair of the Williams System 3-6 [[Media:PSU-Display-PWR.pdf|PSU Board Display Power]].

An attempt was made to create step by step tests so that reading a schematic is not required. Includes replacement parts for the HV section repairs.

If the 1/4A (0.25A) fuse at F1 always blows on power up, you may have a shorted UDN IC chip on the Master Display Driver board.
See this section on [[Williams_System_3_-_7#Master_Display_Drivers_for_System_3_to_6 |Sys 3-6 Master Display Drivers]] for testing all the UDN chips on the display board. You can use these tests for both UDN7180 and UDN6118 (or UDN6184) IC's.

Try removing the master display power connectors. If that stops the F1 fuse from blowing, suspect the Master Display Driver needs repairs before you rebuild the HV section of the PSU. Test the HV outputs of the PSU without any displays connected and see if the proper voltages are being generated from the PSU without a load. You need +5v logic, +100v and -100v supplies to run the Master Display board correctly. This will let you figure out if you need to rebuild the Master Display, the HV section on the PSU Board or both.

'''''From experience, if components on the PSU Board HV section are stressed, it is best to go ahead and rebuild the entire HV section replacing all components with new parts from a $10 kit. It will save you time!'''''

===PSU Parts Suppliers===
Check with: 
[http://www.greatplainselectronics.com/Category-29.asp Ed at GPE] has HV rebuild kits and most parts. 
[http://lockwhenlit.com/Products.aspx Rob Anthony's LockWhenLit] (Borygard from RGP) may also have some PSU parts. 
[http://www.bobramstad.com/pinball/sys6ps.html Bob's PSU parts list] shows the Mouser part numbers which is useful if you live in the USA, or just want to order a few items for your PSU repair.

Also check with your favorite electronics supplier. Please be aware that NTE replacement parts may have wide tolerances so they will be compatible with a greater number of original parts. So get the correct replacement parts wherever possible.

===PSU Diagrams and Resources===
'''Please refer to these files while using this section to diagnose and repair your PSU Board:'''

* [[Media:11-powerwiring-sys4-6.pdf|Williams System 3-6 Power Wiring Diagram]] showing the wiring from your AC mains plug right through to the connection to the PSU board, Sound Board and the G.I.

* [[Media:07-powerlogic-sys3-6.pdf|Williams 3-6 PSU Logic Diagram]]. A PSU Board Schematic for System 3-6 games, containing test points with approximate voltages and help with fault finding your game's power.

* Troubleshooting and repair of the Williams System 3-6 [[Media:PSU-Display-PWR.pdf|PSU Board HV Display Section]]

* External link to a PDF of [http://www.greatplainselectronics.com/Downloads/W3-11_HV_Kit.pdf WMS HV parts and instructions] from Ed at GPE, a great place to get your HV repair kits.

'''Other Resources to visit''' 
Except for the possible use of different transistors for Q1 and Q3 the later System 9-11 HV section is very similar in design. So it will be worth reading through the [[Williams_System_9_-_11#Display_problems |Sys 9-11 Master Display Driver Problems]], for more detail before starting your repair.

'''''Missing PSU Upgrade Sections to add'''''
* Testing the AC in and DC out for all sections, including the Solenoid and Lamp BRs. Simple to do, but should it be spelled out?
* How to fit the replacement transistors with the 'twisted legs' as the SDS-201 and SDS-202 are obsolete. Although a diagram is on the GPE PDF for Ed's HV kit, some shrink wrap tubing could be added to the 'lowest leg' to reduce failures.
* How to fit the 2 x 1n4763a 91v zenerDiodes, at locations Z2 & Z4 to reduce the Display out put to about+/-90v under load and extend display life.
* Repin of Headers at 3J1 and the used pins at 3J2, theory for using crimped trifuricon connectors and new housings which replace the existing female IDC connectors.
...etc.

==The MPU Reset Circuit==
The +12v for reset goes into a circuit that waits (for about a 1 sec. delay) for the +5v to stabilize before it lets the CPU boot. If the +12v (or output from the reset circuit) drops, the reset halts the CPU, PIA(s) and the 5101 CMOS RAM chips before the +5v to them dies. A shutdown of the CPU will also pull blanking low and halt solenoids, lamps and displays to protect them from further damage (coils firing, memory glitching) during the power down. So spikes or drops to the +12v line may halt the CPU at the wrong time.

An MPU unable to boot may mean that its reset circuit is faulty. A +12v line comes in from the PSU board to the MPU on pin 9 of 1J2. That's the top pin on the top left (and only connector on the left) of the MPU board. +12v can also be measured at TP1 on a System 6, 6a, or 7 MPU. Don’t get hung up on it being exactly +12v, as it's not regulated. However, it can’t drop too much lower than +11.5v, or the reset circuit '''may''' have a problem generating enough voltage to keep reset “up” to the CPU. But +11.5v to +14v is not unusual and will still work. A fluctuating reset can cause the game to reboot during a game.

The state of the reset (high or low) can be observed at pin 40 of the 6808 or 6802 CPU chip. Likewise, the reset can be observed at TP8 on System 6, 6a, and 7 MPU boards. TP8 is located just to the right of IC19 (5101 memory) on a System 6 or 6a board, and the far right test point on the bottom of the MPU just above the 40-way connector on a System 7 MPU board. It will be marked as TP8 on the PCB mask. For System 3, 4, 4a MPU boards, the reset will have to be measured at pin 40 of the 6800 CPU board. When booting the game and watching reset, it stays low for a heartbeat after power on and then rises to +5v. +4.75v or around that is fine. Don't get hung up too much on the voltages being exact for the reset circuit either.

If the +12v appears OK when measured, and the sound board is always booting and working, it's safe to assume that +12v at the PSU is stable.

A good trick to 'inject' a reset, is to try connecting +5v for a second or two to the reset test point at TP8 or the leg of the CPU chip (pin 40). If the CPU boots (reset must be a logic high now on pin 40 of IC1), then the reset section will need to be rebuilt..

So that involves running a jumper lead from TP8 and '''briefly''' touching TP9 (+5v). TP9 is located just to the bottom right of the battery holder on a System 6 or 6a MPU board, while it is at the top right the battery holder on a System 7 board. The battery holder should have been removed, so the test point is located in the vicinity of where the original holder '''used to be'''.

===Repairing the Reset Circuit 'Divide and Conquer'===
Assuming that the game boots and works if the CPU reset pin is held high, how can it be determined what is wrong? One solution is the shotgun method: just start changing transistors and components until it is fixed. However, this wastes time and parts. A better way is to narrow down the fault location using the 'injection' trick.

The reset circuit is easily seen as two halves. For a System 7 MPU board, +5v can be applied directly to the top of resistor R12. If the board boots and stays stable, then that indicates the problem is on the 'right hand' side of the circuit. (On System 6, the same thing can be done, but using R32. This method helps narrow down the faulty components by a half.)

Assuming that the +12v getting to MPU board is good, if the above injection of 5v doesn't work, measure where the voltage disappears on the left hand side of the reset circuit. Then replace parts on that side, checking for a good reset when the board boots each time. Remember that for System 6 and 7, there are just 12 active components that make up the reset circuit, and 8 of those are transistors. Those are usually the source of the problem.

===Step One===
The Right Hand Side.
Start by replacing transistors Q6 – Q9 (all 2n4401 NPN) get 10 or more of them, they’re cheap to buy and they are commonly used. They are used as pre-drivers for the solenoid power transistors on the driver boards for System 3-7).

Test the board for the previous booting problem. If they are still there, replace the two zener diodes: ZR1 is a 6.8v Zener (1n5996) and ZR2 is a 3.9v Zener (1n5990) - you can't replace these components with anything else to my knowledge. These are critical values. And put the orientation of the band of the diode the same way as the ones that are removed. Taking a photo of how the circuit in the top left of the board looked before making any changes is a good idea. Or, only replace components one at a time. A test boot could be done on the bench each time something is replaced, but that may slow things down. On the other hand, this may result in avoiding replacing more components than necessary.

It should be booting now, if not attack the other half.

===Step Two===
The Left Hand Side.
Start by replacing transistor Q2. Q2 is a 2n4403 PNP transistor, cheap as well but you won’t need as many for pinball repairs. then replace Q3-Q5 with the 2n4401 's like before. I would replace D19 (a 1n4148 fast switching diode) you could test it with the diode setting of your DMM, but I don't trust testing diodes in circuit, and if I’m soldering in that section, I just cut it out and replace it. Cost will be pennies, and most pinball people should have new ones on hand. Again, be sure and notice the direction of the band on the old diode, and put the new one back the same way. Same thing goes for the orientation of the flat side of the transistors. Don’t get them wrong when replacing. The last component to replace would be the capacitor at C27 (10 uF @10v is the original part –look on the side of the cap). Replace it with a tantalum 10 uF @ 16v, if you can find it. You can go up in voltage even to 20v or more, but don’t change the value of the capacitance. Note that some caps have markings showing a (-) side, usually running down the side of the capacitor. If it shows a polarity, the (-) side of C27 points down on the PCB, towards the 40-way interconnect.

===Step Three, Hopefully Reset is Back Up===
That’s it. Usually fixed at step one, and down to one (or more) of those transistors. I have seen a zener or the 1n4148 diode at D19 be the problem before. But for me, the cap C27 has always been good. If all else fails, test the capacitor for a dead short with the power off and replace it with a 10uF electrolytic if it is shorted to ground or you aren't sure it's working.

===An Alternative to Rebuilding the Reset Circuit (System 6 and 6a)===
[[File:WMS Sys6 Reset Stock.jpg|left|thumb|300px|Williams System 6 MPU board stock reset circuit]]
[[File:WMS Sys6 MPU Reset Gen.JPG|right|thumb|300px|Williams System 6a MPU board reset circuit with an MCP130-460GI/TO reset generator installed]] 
There is an alternative to the stock reset circuit on System 6 and 6a MPU boards. A reset generator can be installed. To do so, some components will need to be removed and two jumpers installed. The following work will have to be done.
 
#Remove the following transistors - Q4 and Q6
#Remove the following resistors - (from left to right as installed on the board) R43, R38, R39, R41, and R42
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP130-460GI/TO where Q4 was (green highlighted area in image). Orient the reset generator in the same manner Q4 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q4). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the top pad and bottom pad of where R39 was (yellow highlighted area in pic). Essentially, replace R39 with a zero ohm jumper.
#Add a jumper between the top pad of R42 and the "C" collector pad (top pad) where Q6 was installed (orange highlighted area in pic).
 

This a very simple, and in some cases, cheaper alternative to repairing the existing reset circuit. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 6 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from [http://www.greatplainselectronics.com/proddetail.asp?prod=MCP130-460GI%2FTO Great Plains Electronics].

[[File:WMS_Sys6_Reset_Gen-Pullup.jpg|right|thumb|300px|Williams System 6A MPU board reset circuit with an MCP120-460GI/TO reset generator installed with a pull-up resistor]] 
Alternately, an MCP120-460GI/TO reset generator can be used, except a 4.7K 1/4 watt pull-up resistor will have to be added to the reset signal line.

#Remove the following transistors - Q4 and Q6
#Remove the following resistors - (from left to right as installed on the board) R43, R38, R39, R41, and R42
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP120-460GI/TO where Q4 was. Orient the reset generator in the same manner Q4 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q4). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the bottom pad of where R38 and R39 formerly were.
#Add a 47k 1/4w resistor between the top pad of where R38 was and the bottom pad of where R41 was.
 

===An Alternative to Rebuilding the Reset Circuit (System 7)===
[[File:WMS Sys7 Reset Components Remove.JPG|left|thumb|300px|Components to remove from a Williams System 7 MPU board reset circuit]]
[[File:WMS Sys7 Reset New Components.JPG|right|thumb|300px|Williams System 7 MPU board reset circuit with a reset generator installed]] 
Like the System 6 and 6a MPU boards, a reset generator can be installed on a System 7 board. Some components will need to be removed, a single jumper installed, along with a 4.7k ohm resistor installed. 

Procedure
#Remove Q2 transistor
#Remove the following resistors - (from left to right as installed on the board) R27, R24, R31, R25, R29, and R30 (resistor located to the right of Q2)
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP120-460GI/TO where Q2 was (this is the same reset generator as used on Data East MPUs). Orient the reset generator in the same manner Q2 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q2). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the bottom pads where R27 and R24 formerly were.
#Add a 4.7K ohm 1/4 watt resistor in place of R25.

[[File:System7ResetSection.jpg ‎|left|thumb|300px|All components of the reset section have been scraped except those required to use the MCP120-460GI/TO reset generator (marked with gold Sharpie). In this picture, the 74125 stuffed at the factory has been removed as it's original function was to read the DIP switches. System 7 games do not read the DIP switches.]] 
This a very simple, and in some cases, cheaper alternative to repairing the existing reset circuit. After this modification is performed, the MPU will no longer need the +12VDC to successfully boot. The remaining components in the reset circuit can be removed if desired as pictured at left. The MCP120-460GI/TO reset generator can be purchased from [http://www.greatplainselectronics.com/proddetail.asp?prod=MCP120-460GI%2FTO Great Plains Electronics].

Note: if using the MCP130 variety of reset generators, the 4.7K ohm resistor does not need to be installed as they incorporate the resistor internally.
 

===Reset Circuit Summary===
Connectors were mentioned above for completeness. While I agree a good 40-way connector is essential for correct operation of this era of games, changing the Bridge Rectifiers in the backbox or rebuilding connectors probably won't help fix the reset circuit .

That because the '''BR's are only for the Lamps and Solenoids''' and won't fix a problem with the MPU power (or reset) as that is sourced directly from the PSU. The +5v logic power comes from a regulator on the PSU board, and the +5v for the reset pins of the MPU ICs is created on the MPU from the +12v unregulated supply.

If you are looking here because game resets (reboots to attract mode or locks up) when flipping the flippers, it makes sense to check and rebuild the solenoid power circuit as well. That is the flipper power on games prior to System 7 when 50v flippers and a Flipper Power Board was introduced. You should also read the [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#WPC_5VDC_Power_Derivation_Path WPC section], while the games only similar- the approach for resets caused by power fluctuations is sound. It takes you from the 'AC mains' wall plug right through to the power needed on the boards.

Topics such as electrolytic capacitors aging and drying out, testing the Bridge Rectifiers and checking and tweaking the LM323K 5V regulator on the Power Baord will all be the same or very similar.

==The Blanking Circuit==
The blanking circuit is used by the MPU to prevent damage to the game when the MPU can not determine that the game is in a valid state. A low blanking signal means that the MPU isn't operating properly and the blanking circuitry is "blanking" (turning off) the lamps and displays. A high blanking signal means that the MPU is operating normally, allowing lamps and displays to function normally.

On the driver board, the blanking signal is logically ANDed, by 7408s, with the enable signal for all 8 of the lamp strobes and the first 16 solenoids. The 6 special solenoid enable signals are not ANDed with the blanking signal. 

On the MPU, the blanking signal for the displays leaves the board via connector IJ3 pin 4 (top left connector on board). For the driver board blanking signal, it leaves the MPU board at pin 37 of the 40-pin interconnect.

A special note: the blanking signal will only go high when the MPU and driver board are connected. It will not go high if testing with a stand alone MPU board.

===Adding a Blanking Indication LED to the Driver Board===
[[File:WMSSystem3-7BlankingLED.jpg|thumb|400px|left|A "blanking" LED added to a Williams System 3-7 Driver Board.]] 
Adding an LED as shown in the image will let you easily monitor the Blanking state while troubleshooting. Note that the "flat side" of the LED faces away from the 40-way connector and is on the same side as the shorter lead. The “current limiting” 150 ohm resistor is soldered to the ground trace. 
 

===Adding a Blanking Indication LED to the System 6/6A MPU Board===
[[File:WMSSystem6MPUBlanking.jpg | thumb | right| 400px| A blanking signal indication can be added to a System 6 MPU quite easily.]] 
#Remove the TP4 test stud. This is the blanking stud.
#Install the "non flat side" of the LED into the open hole.
#The "flat side" of the LED is oriented up, or toward the top of the board.
#Solder a 150 ohm (or so) resistor between the flat side lead and ground trace that has a zero ohm resistor soldered to it.
#All done.
 

===Adding a Blanking Indication LED to the System 7 MPU Board===
A blanking signal indication can be added to a System 7 MPU can be done in at least two very clean ways. 
When the LED is lit, the blanking signal is high, indicating a properly functioning MPU. 

==== Option 1 ====

Implementing this modification assumes that the battery holder trace is no longer in use! 
Procedure
#Remove the Blanking test point stud (numbered "4"). Since we are adding a blanking indication LED, the stud is no longer required.
#Install an LED, with the flat side pointing toward the former location of the battery holder and the other leg through the hole created by removal of the blanking TP stud.
#Bend the LED lead through the former battery holder hole and solder.
#Form a 150 ohm 1/4W resistor between the appropriate battery holder hole and the fat ground trace along the perimeter of the board.
#Scrape the solder mask from the board, enabling the resistor to be soldered to the ground trace.
#Solder both ends of the resistor.
#Add a label to indicate the meaning of the LED; lit means blanking is on and the MPU is working properly; unlit means blanking is off and there is a problem with the MPU.
 
<center>
<gallery widths=480px heights=480px perrow=2 caption="Option 1: Adding a Blanking Signal Indication to a System 7 MPU">
File:WMSSystem7BlankingLEDFront.jpg|<center>An LED replaced the Blanking test point stud, flat side pointing toward the battery holder hole.</center>
File:WMSSystem7BlankingLEDBack.jpg|<center>The back of the System 7 MPU, showing connections of the LED, repurposed battery holder trace, and 150 ohm resistor connection.</center>
</gallery>
</center>
 

==== Option 2 ====
This method does not require the battery holder to be removed. 
Procedure
#Clean the original solder from the lower of the 4 "paired" solder pads and the "via" pictured below.
#Install an LED, with the flat side oriented as indicated by the silkscreen
#On the solder side of the board, connect a 150 ohm 1/4W resistor to the LED lead on the "flat side" of the LED.
#Solder the other end of the resistor to the large ground trace.
#Bend the "non flat side" lead of the LED so that it can pass through the via hole and solder securely. This connects the LED to the blanking signal.
#On the solder side of the board, sever the trace shown in the image below that runs NorthEast from the LED (trace severed at gold dot using a Dremel tool and ball cutter bit).
#Add a label to indicate the meaning of the LED; lit means blanking is on and the MPU is working properly; unlit means blanking is off and there is a problem with the MPU.
 
<center>
<gallery widths=480px heights=480px perrow=2 caption="Option 2: Adding a Blanking Signal Indication to a System 7 MPU">
File:S7BlankingFront.jpeg|<center>An LED added to available solder pads, flat side pointing in the same direction as indicated on the silkscreen.</center>
File:S7BlankingBack.jpeg|<center>The back of the System 7 MPU, showing connections between the LED, a 150 ohm resistor connected to ground, and the "non-flat-side" lead of the LED connected to the blanking signal.</center>
</gallery>
</center>
 

===Blanking Circuit Stuck Low===
The blanking circuitry that appears on Williams 3-7 MPU boards remained the same across all generations of Williams MPUs, all the way through the System 11 board set. Data East copied the same blanking circuitry too!

The blanking circuit explained

#A properly executing CPU will send data to the display 6821 PIA at IC18 at regular intervals.
#This action causes PA2 at pin 4 of the 6821 at IC18 to periodically pulse.
#The signal is inverted by the 7404 at IC7, in at pin 5, out at pin 6.
#The coupling capacitor at C32 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q5 and to pin 8 of the 556 timer at IC23.
#The 556 timer is configured as a "missing pulse detector" meaning that if it does not detect the pulse that originated upstream at the 6821 PIA at IC18, the output of the 556 timer at pin 9 (and 13) will go low, which invokes blanking and protection of the system circuitry.

Upon a successful boot of the MPU board, the blanking will go from a low signal to a high signal, and remain high (no pulsing) as long as there are no issues. If the blanking signal does not go high, the system has not and will not boot. 

One of the most common issues for a blanking signal to remain low is discontinuity between the MPU board and the driver board. The blanking signal passes via the 40-pin interconnect at pin 37 (4th pin in from the left side). Poor connections due to fatigue or seeping battery damage can cause a break in this connection. It is best to replace both the male and female sides of the 40-pin interconnect to ensure that all is well. Remember, the blanking will not go high, if the MPU is not connected to the driver board. A flaky connection with discontinuity between boards is the same as if they're not connected. 

[[File:WMS Sys6 MPU Ground IC5.JPG|left|thumb|300px|A System 6 MPU board with the upper right battery holder through-hole circled, along with the ground trace and the 74LS02 labeled.]] 
A special note about System 6 & 6A MPU boards. The upper right through-hole for the battery holder passes the ground from the solder side of the board to the IC5 (74LS02) chip. This through-hole can become compromised from battery corrosion or the careless removal of the battery holder. If there is a break between the two sides of the board, ground will not be connected to IC5, and the chip will not function. If this occurs, the blanking signal will never go high, and the board will not boot. Just check for continuity between pin7 of IC24, the top right leg of chip shown and TP10, the bottom post on the right of picture. You may have to add a ‘stitch wire’ soldered to the top & bottom of the board going through the hole indicated. 

[[File:WMS_Sys7_Blanking.JPG|left|thumb|300px|System 7 MPU board blanking signal trace]]
A special note about System 7 MPU boards. The trace for the blanking signal is very fragile. If the batteries have leaked on the board, or leached under the 40-pin header pins, make certain that the trace which carries the blanking signal has not been broken. The break most commonly occurs at the junction of the trace and the component side of the through-hole pad for the header pin on the MPU board. A continuity test can be performed to determine if the trace has been compromised. Place one lead of the ohmmeter on TP4 and the other on pin 37 of the 40-pin header. Also, keep the lead on TP4, and place the other on the 12th pad up on the far right of the board. The header pin connector will have to be removed to inspect this junction, should there be a break. 

===Blanking Circuit Strobing===
There is a peculiar instance where the blanking circuit will be strobing. The end result is erratic behavior from the displays and lamps (both the lamps and displays will be very dim if at all visible during attract mode). The prime source of this issue is due to the C31 capacitor (1.0uF 25v axial tantalum) falling out of spec.
 

==Driver Board Issues==

===The "Once Dreaded" 40-pin Connector===
The driver board mates with the MPU board using 40 x 0.156" extra long header pins on the MPU and female 'bottom entry' Molex sockets on the driver board. Common belief is that these connectors are good for about 25 reliable connects and removals. While there may be disagreement with this number, the fact remains that the connector is good for a limited number of uses before the connection degrades. At that time, the connector must be replaced. 

The connectors between System 3-7 MPU and driver boards were/are a continual source of problems for this era of Williams machines. However, the issue was eliminated with the release of System 8, (and the more common System 9 platform), when the MPU board and driver board were merged together into a single board. 

If the header pins on the MPU board aren't tarnished, burned, or previously sanded, you may be able to get away with re-flowing the solder on these pins following these steps.
* Heat up the pad, add a little new solder
* Remove all the solder you can (the old and new) with a solder sucker
* Add fresh solder back to get a nice flow around each pin

[[File:Wms drvr interconnect.JPG|left|thumb|300px|The 40 pin female connector on the driver board]]
Then, replace all the female connectors on the driver board. Even if the driver board side pins look good, replace them. Simple cleaning of the pins with a contact cleaner or burnishing them are not viable solutions. The bottom feed pins loose tensile strength over time, which degrades the connection between the MPU and driver board as they age. The picture at left illustrates the 40 pin female bottom feed connectors on the driver board. It should be noted that the connector in the picture is an extreme example of poor condition connections. Missing and alkaline damaged pins, connectors from position 17-40 on the left, are not the norm. Connections from position 1-16 on the far right are more commonly seen.
 

[[File:WMS Interconnect Back.JPG|left|thumb|300px|Installing a new 40 pin female connector on the driver board]]
[[File:WMS Interconnect Front Done.JPG|right|thumb|300px|A new 40 pin female connector installed on the driver board]]
If using four 10 pin female connectors, (the originals on the driver board were five 8 pin), here's a little trick to keep them lined up nicely when soldering them. Take the old 8 pin male header pin connectors, which were installed on the MPU board. Install three of the 8 pin headers on the back side of the driver board and into the new female connectors (see picture to the left). If any of the older header pin sections have battery corrosion on them, do not use use them for this. Allow enough space between the connectors so some of the female connector leads can be soldered. Solder all of the exposed leads on the female connector. Once they are soldered in place, remove the male headers, and solder the remaining leads on the female connectors.
 

[[File:Male40PinHeaders.jpg|right|thumb|300px|Fresh male headers installed on this System 6 MPU. Nice. Note the new headers are 10 pins long while the original headers were 8 pins long.]] 
Parts for the MPU are:
*Square .156" header pins. These can be found at Great Plains Electronics [https://www.greatplainselectronics.com/proddetail.asp?prod=2420-10-2260 here]. Alternatively, Molex brand longer pins, part number 26-48-1080, can be used. Both of these options meet the length requirement for the pins to be at least 0.629" or 16mm length.
Parts for the Driver board are:
*10-way 0.156" Bottom Entry Female Molex Part Number: 09-52-3102 (4 needed per board). The original part, 5A-9066 8-way .156" Female Molex Part Number: 09-52-3082 (5 needed per board). Alternates are Molex 09-62-6104 and 09-52-3102 which are hard to obtain. 

Check with:
[http://www.greatplainselectronics.com/Category-82.asp Ed at GPE] or your favorite supplier for these.
 

[[File:UsingFemaleHeadersToAlignMaleHeaders.jpg|left|thumb|300px|Female housings being used to align the male headers.]] 
A trick similar to the method aligning the female housings can be used to align the male headers. Use the old (or new one housings) to align the male headers as pictured at left.
 

There is no substitute for doing this correctly, other than buying reproduction boards. A solution is a board made by Rottendog Amusements, where the MPU and driver board are [http://www.rottendog.us/?product=mpu327 combined into one board]. Cost is anywhere from $350 - $400. Another option is purchasing both the [http://www.pinballpcb.com/System3-7MainBoard.html MPU] and [http://www.pinballpcb.com/System3-7DriverBoard.html driver board] from Kohout Enterprises for $425. When both boards are purchased, they can be tied together via an auxiliary ribbon cable. Of course they can be connected via the 40-pin interconnect too. 

If doing it yourself, repairs on the MPU and driver board connectors can cost up to $30 or less in parts (header pins, sockets and solder), along with several hours to replace the connectors and pins correctly. This of course depends on your level of soldering skills and the value you put on your time. It's a fairly long job but it's likely that it only needs to be done once.
 

==Display Issues==
===Every-Other Digit Shown On All Displays===
[[File:WilliamsSystem3-6EveryOtherDigitOut.jpg ‎|thumb|left|300px|Half of the digits, or every-other digit, are missing on all displays. Unintuitively, the root cause of this failure is the lamp matrix 6821 PIA at IC10 on the driver board.]] 
This failure seems to occur quite frequently and perplexes most techs. While the 6821 in the MPU display interface circuitry would seem to be the logical culprit, it is the lamp matrix PIA on the driver board that is the actual villain. The issue shown at left was remedied by replacing PIA III (also known as IC10), the lamp matrix drive PIA, which is the middle PIA on the driver board.

[[File:YT.png]] A YouTube video demonstrating this failure, and the correction, can be found [https://youtu.be/ckwoW_xuQSM here].
 

===Repairing the Master Display Driver===
Note that the detail here is for System 3 - 6a with 6-digit displays only. So it does not include Alien Poker or Algar, which both used the System 7 type display setup. System 7-9 used a smaller Master Display Board located on the back of the lamp board, and it had IDC type ribbon cables that ran to the 4 player 7-digit displays. They added a 4-digit Credit/Match display which also used a ribbon cable. The harness connecting the backbox (PSU and MPU) signals to the Master board used the same 'edge-connector' as System 3-6).

===First, a High Voltage '''***Warning***'''===
With the game on you are dealing with +100 and -100v HV DC (High Voltage) going to the displays. That's a potential 200v difference and you only need to feel that once to know it. Wear tennis shoes (trainers or any rubber soled shoe) when working on displays with the backbox open. This is a shock hazard! If you are not capable or happy with measuring these voltages with a steady hand, then get someone else to help you and be there to 'spot' you. Always a good idea and more fun than working on your own.

Another useful tip is to remove Fuse F1 from the PSU (Power Supply Board). This is the HV fuse and is 1/4A Slo-Blow (250mA 'T' fuse in Europe). This will allow the logic (BCD binary decoders and Buffer ICs) to be troubleshooted with a DMM or Logic Probe without the danger of shocks or shorting them out when measuring TTL (logic) voltages. It may also save the logic probe from a crispy fate.

===Master Display Wiring Harness===
Sometimes displays just go blank and it is a fault in the wiring harness from backbox to the Master Display Driver. If you can swap a working Master Display Driver board from a System 3-6a game with stable displays, then do that as a first step. This way you quickly determine if the fault is in the backbox '''OR''' the Master Display Driver PCB or displays on the front of the light board. If it's the towards the backbox then suspect display harness cabing Driver to MPU, or the display PIA or decoding on the MPU. If you don't have the ability to swap in a spare Master Display board, then turn off the game and test the harness for continuity between the backbox (MPU board) and the cables at the left and right side of the Master using this ''[[media:10-displaywiring-sys-4-6.pdf|Master Display board harness wiring diagram]]''.

===Segment failures===
Segment failures on a single display could be that display failing. Same issue if just one display is blank. Swap that display with another (power off first) and see if the problem moves with that display. If it moves, it's that display glass or its board. If it doesn't move and stays at the same player location, see below for the possible suspects.

Segment failures on multiple displays and probable cause:

Players 1 & 2 Segments and master display Segments are out:
* BCD inputs are A1 B1 C1 D1 from the MPU board
* MC14543 BCD to 7-Seg. Decoder IC5
* UDN7180 Display Driver IC9
* Resistors R1-R7

Players 3 & 4 Segments
* BCD inputs are A2 B2 C2 D2 from the MPU board
* MC14543 BCD to 7-Seg. Decoder IC8
* UDN7180 Display Driver IC10
* Resistors R8-R14

Start out by measuring all the resistors on the master display board with the power off.
R1-R14 should be around 10K ohms. Any that are not within about 10% (say a range between 9.6K to 10.4K ohms) need to be replaced. Also look and see if any look "toasted".

Those resistors get cooked on the Master display boards and usually will then cause single segments to fail on both the player 1&2 or 3&4 displays together, as they are linked. Te resistors need to be replaced with the same value: 10K but at 1/2 Watt. Some of the modern 'metal film' resistors are rated at 0.6W which is perfect and they fit nicely in that location. Older 0.5W (1/2W) resistors are larger, but are fine. Mount them slightly off the PCB so they get good airflow all around the resistor body.

Do the above steps anyway, no matter what the display problem is although it's probably not going to be the whole story.
Replacement resistors are cheap and will prolong the life of your displays. Reducing the voltage going to the displays when rebuilding the HV section of the PSU is a good step to take and will help as well. You only need to replace two Zener diodes to achieve this.

===Digit Failures===
Strobe inputs for the display digits come in to three 14069 hex inverters on the driver board. IC1, IC2 and IC3.
* IC1 is dedicated to the Master Display 'Credit/Match'. Strobes are: 15,16,7,8 left to right, for the 4 digits it uses.
* IC2 and IC3 strobe inputs are more complicated, to strobe distribution between these IC chips is shown in the display diagram below.

Strobe (or strobe input) failures are likely to show up in the player display pairings 1&3 or 2&4 because:
* Strobes 1-6 are shared for players 1 & 3
* Strobes 9-14 are shared for players 2 & 4

===All Displays are Blank===
This could be that the +100v or the -100v HV are missing from the PSU board. Both have to be there, so check that the output from the PSU and that the voltages (HV) are good first, and getting to the Master display driver to be relayed to the player displays.

There are also 5 x 3 Mega ohm resistors, at R15-R19, These are for the cathode "keep alives" and again should be near that value. If the 3 Meg resistors don't look cooked and are within spec, check that you can see an "orange glow" in the displays when the lights in the room are dim or off. If you see a faint glow (some describe it as an 'orange neon dot'), then look elsewhere for the fault.

If you don't see the display glow, check the wiring to the connectors carefully looking for a burnt wire at pins 4J7-1 -2 and -6
on the master display. Do this with the power off, as you are dealing with 100v and -100v DC. If you find a cooked wire, sometimes just cutting the wire back a bit to expose clean metal and then reinserting it firmly in the IDC connector will repair the problem with a bad connection for one of the HV lines. Remove and reseat all the edge connectors on the master display board and especially examine the ones that go to the backbox. You can clean the copper contacts on the edge connectors gently with an eraser to shine up the copper if it's dull or has "dead spots" worn on it. Check any inline connectors as well.

I also recommend disconnecting all the player displays 1-4 at the Master display. Get it working with the just the credit/match and
then with one other display attached, like player 1. Then add back the player 2-4 displays one at a time (you need to power off each time you add or swap a display), testing for correct function each time. You can also swap the player displays as a diagnostic step and carefully observe if the fault(s) stay with the Display in question or move to the new location. Use the "display test" on the diagnostics for this. After the above is checked, perhaps you do have to suspect the IC chips (or for the discrete version the transistors). Depending on whether the Segments or Digits are out, it will point you at a specific IC (or transistor array). Knowing which displays are out helps reduce the fault domain down to one chip. You need be like a detective, following the clues. Having a Master Display Assembly drawing and a schematic on hand will help with this process.

Here's hoping that it isn't one of the UDN6118A-1 (aka UDN6184-5) IC chips that's faulty. Hard to remove from another board in one piece, without a de-soldering station and becoming obsolete.

Also, check that the display blanking connector is in place. This will be a 4 pin connector with a single wire. If this connection has failed or has been unplugged, the game will boot, go into attract and seem to be working, but the displays will remain blank.

===Displays only showing even number===
This is caused by a display signal connector issue. This shows up in pairs; player one and two or player three and four. Likely to be header pins on MPU board connector J5, J6, J7

===Scrolling Digits on Display===
The rather unusual issue of "scrolling digits" on the displays is caused by failed/failing filter capacitors on the power supply board. Over about 40 years of operation, these capacitors begin to fail and no longer effectively filter the high voltages. The OEM capacitors were rated at 100uf/150V. These capacitors can be replaced with 220uf/160V axial capacitors to correct this behavior.

A video of this behavior can be found [https://www.youtube.com/watch?v=QxIRdJ7ecBY here.]

===System 3-6 Displays===

====System 3-6 Master Display Driver Boards====
Master Display Driver Boards came in two versions, discrete and IC based. Williams designed the discrete version when the UDN7180 / UDN6184 Gas Plasma Display Driver ICs became scarce (and they were expensive even then). There are some logic chips that decode the BCD data for the 7 display segments (MC15453 or MC15458) and to buffer and invert the display strobe lines for the digits (MC14069). These buffers and decoders are common to both the D8000 and D8168 versions.

=====Discrete version Display Driver=====

[[File:WMS sys3-6 master display discrete.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Discrete Components)]] 

The D8168 board uses MPSA92 (PNP in a TO-92 package) and MPSA42 (NPN also TO-92) transistors to drive the Master (Credit/ Match) and player scoring displays. These gas plasma display driver transistors are available today and still very cheap to buy. Unfortunately, this style of board is less common to find in the wild, but actually easier to maintain. At least no one can try to charge you $20+ for an obsolete driver IC.

 

=====IC version Display Driver=====

[[File:WMS sys3-6 master display.JPG|300px|thumb|left|Williams System 3-6 Master Display Board]] 

The D8000 IC version board is composed of ICs that implement the transistor arrays. Usual factory chips are the UDN-7180 for the Segment Driver and the UDN6118a-1 for the Digit Driver. You may find the Digit Driver IC is a UDN6184-5 as well from Williams.
 

The UDN-7180 IC chips are still fairly easy to find. Cost should be reasonable, if you shop / ask around. (Sprague) or uPA6118c may still be available for $3-5 but have a lower breakdown voltage (~85v DC) than original part. The displays run at +/-100v DC as standard and need the higher rated original part which is the the UDN6118A-1 (note we have -1 at the end). The UDN6118a-1 is rare and also becoming very expensive, as much as $20+ for an IC chip.

If you do find the '''lower rated UDN6118a (or uPA6118c)''', then you will need to replace two zener diodes on the PSU to lower the display voltage down from 100v. It's a good idea anyway on a working System 3-7 game. Not overdriving display glass and less stress on the expensive display driver chips will lengthen the life of your game. Arcades sometimes had bright lights or windows, while in your home you won't notice any difference running at a lower voltage.

I usually drop the voltage down leaving the Power Supply to about +/- 90v with 2 x 1n4763a 91v zeners, at locations Z2 & Z4. This seems to work well, but you are still probably driving near the limits of the replacement UDN6118a. Unlike the Bally games of the same era, there is no fine adjustment on the voltage output of the HV section of the PSU.

See the Power Supply repair section for more information about parts to use and other upgrades.

Remember to compare the costs and trouble of repairs with buying a replacement Master Display Driver board:
* If all that is wrong with the Master is that the Credit/Match display is out, but it drives all player displays correctly, in my experience the repair is easier than on the player display parts of the driver board:

* '''Carefully placing a new 6-digit glass against the pins of the non-working display will confirm if it is the display glass or an IC chip that has failed.''' Be Careful of the HV (High Voltages) when doing this, and only hold it by the display glass as it is a natural insulator! It takes a steady hand and some practice, but this test will work on other player displays as well. This usually proves the old display has a digit/segment missing, is 'out gassed' or is just prone to flickering. This isn't foolproof, it works works provided the existing display doesn't have a short. If both displays exhibit the fault, cutting the correct 'leg' or legs in the middle on the old display may help reveal this, and you can bend it back and solder back together if it's not shorted.
** You replace the Master display glass with a standard 6-digit gas plasma display, you can even use an old (but working) player display.
** You can also replace the Master display with a player display that has a digit fault and would otherwise be unusable! It's possible because the '100,000s' and '100s' digits are not used on the Master [x00x00]. So you can take two faulty components (a non-working Master and non-working player score display) and make a working Master Display Driver Board. Pinball repair nirvana.

Once you feel the display glass is good, you can look to the ICs which are dedicated to driving the Master (or Credit/Match) Display:
* Start by testing IC1, a 14069 Hex Buffer/Inverter with your logic probe. Run the display digits diagnostic test, with the Auto/Manual switch in the Auto/Up position. The digits on all displays should be counting 0-9. Test the strobe lines are being inverted. The strobe lines and associated pins are in the diagram given below.

When reading this diagram remember that Player 1&3 Score Displays share Strobes 1-6, while Player 2&4 Score Displays share Strobes 9-14. One strobe for each digit.

The Master Display has 4 digits only: Strobes 7,8,15,16. So if the output pin is not the inverse of the input pin or a signal is missing, then replace IC1. It's available as a 4049U or MC14049UB. Cost is maybe 50 cents, certainly < $1 even in low numbers. Useful chips to buy and have around, as the 4049 is also used on the System 3-7 Driver Board for the switch matrix and on other later games.

[[File:Sys3-7-Displ-Digit-Driver.jpg]]
 
Digit failures will show up in these pairings if they are related to the strobes (so digit drivers):
* Strobes 1-6: shared for players 1 & 3
* Strobes 9-14: shared for players 2 & 4
* The Diagram below is the same for all games, as are the Master Displays which makes them interchangable:
* The Table / Diagram is listed in the most obvious order: Master, Player 1,2,3,4 displays.

This is a clearer Table from the above diagram:

{| class="wikitable"
!colspan="4" |MASTER DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT DRIVER
!STROBE
!4049 INVERTER BUFFER
|-
|align=right|(Left) 10,000||IC4 pin 1 / 18 ||align=center|15 ||IC1 pin 11 /10
|-
|align=right|1,000 ||IC4 pin 3 / 16 ||align=center|16 ||IC1 pin 1 / 2
|-
|align=right|10 ||IC4 pin 5 / 14 ||align=center|7 ||IC1 pin 3 / 4
|-
|align=right|(Right) Units||IC4 pin 7 / 12 ||align=center|8 ||IC1 pin 5 / 6
|}

{| class="wikitable"
!colspan="4" |PLAYER 1 DISPLAY
!colspan="4" |PLAYER 2 DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
|-
|align=right|100,000 ||IC11 pin 1 / 18 ||align=center|1 ||IC2 pin 5 / 6||align=right|100,000 ||IC11 pin 7 / 12 ||align=center|9 ||IC3 pin 9 / 8
|-
|align=right|10,000 ||IC11 pin 2 / 17 || align=center|2 ||IC2 pin 3 / 4||align=right|10,000 ||IC11 pin 8 / 11 ||align=center|10 ||IC3 pin 5 / 6
|-
|align=right|1,000 ||IC11 pin 3 / 16 || align=center|3 ||IC2 pin 1 / 2||align=right|1,000 ||IC12 pin 5 / 14 ||align=center|11 ||IC3 pin 3 / 4
|-
|align=right|100 ||IC11 pin 4 / 15 || align=center|4 ||IC2 pin 9 / 8||align=right|100 ||IC12 pin 6 / 13 ||align=center|12 ||IC3 pin 13 /12
|-
|align=right|10 ||IC11 pin 5 / 14 || align=center|5 ||IC2 pin 11 /10||align=right|10 ||IC12 pin 7 / 12 ||align=center|13 ||IC3 pin 11 /10
|-
|align=right|Units ||IC11 pin 6 / 13 || align=center|6 ||IC2 pin 13 /12||align=right|Units ||IC12 pin 8 / 11 ||align=center|14 ||IC3 pin 1 / 2
|}

{| class="wikitable"
!colspan="4" |PLAYER 3 DISPLAY
!colspan="4" |PLAYER 4 DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
|-
|align=right|100,000||IC12 pin 1 / 18 || align=center|1 ||IC2 pin 5 / 6||align=right|100,000 ||IC13 pin 3 / 16 || align=center|9 ||IC3 pin 9 / 8
|-
|align=right|10,000 ||IC12 pin 2 / 17 || align=center|2 ||IC3 pin 3 / 4||align=right|10,000 ||IC13 pin 4 / 15 ||align=center|10 ||IC3 pin 5 / 6
|-
|align=right|1,000 ||IC12 pin 3 / 16 || align=center|3 ||IC3 pin 1 / 2||align=right|1,000 ||IC13 pin 5 / 14 ||align=center|11 ||IC3 pin 3 / 4
|-
|align=right|100 ||IC12 pin 4 / 15 || align=center|4 ||IC3 pin 9 / 8||align=right|100 ||IC13 pin 6 / 13 ||align=center|12 ||IC3 pin 13 /12
|-
|align=right|10 ||IC13 pin 1 / 18 || align=center|5 ||IC3 pin 11 /10||align=right|10 ||IC13 pin 7 / 12 ||align=center|13 ||IC3 pin 11 /10
|-
|align=right|Units ||IC13 pin 2 / 17 || align=center|6 ||IC3 pin 13 /12||align=right|Units ||IC13 pin 8 / 11 ||align=center|14 ||IC3 pin 1 / 2
|}

If that doesn't fix it, next move on to the Segment Drivers:
*Look at IC4, the UDN6118A, follow the steps to do a DMM test of the UDN chip. A trick here can be that all the pins are not used (because of the missing digits, so it is possible to make use of the original UDN6118-A-1 (or UDN6184-5) that has a previous fault and one I/O pair is faulty.

This works for the Master Display, so I would keeep a faulty UDN chips (or a faulty board) for spares. You never know (e.g. there is an ''extra unused pair'' on every UDN7180 type chip pins 1+18 when we get to Segment driver tricks!!! This does not work when you get to for System 7-9 Masters, as all the pins are used.

Pairs that '''are needed''' for IC4 are: (1,18) (3,16) (5,14) (7,12). So you can get away without pairs: (2,17) (4,15) (6,13) (8,11) so you can have up to 1/2 the chip faulty, but it needs to be the right positions without using wire jumpers.

There is a way to test the UDN6118's with the power off and your DMM (multimeter).
*'''With the game OFF''':
**Remove the power in to the Master Display board, connector 4J7.
**DMM goes on the Diode test setting, usually a symbol like this: ->|
**Red lead clipped to ground, I use the ground braid in the backbox, or on the display board connected by a jump lead (alligator clips each end)
**Touch black lead to the UDNxxxx pins 2 through 8
**You should get .5 to .7 for each pin 
**Then touch Black lead on each UDNxxxx pins 17 through 11.
**An open reading (no reading) is the correct result.
**A shorted display glass can show up during the UDNxxxx 11 through 17 test.
[[Image:UDNReading.png|left]]
 

Shorts Are Found in UDN Chip Test 
If a short reading is found in the tested pins (don't test the pairs 1,18 and 9,10), the UDN chip should carefully be desoldered and removed from the board. Take care to preserve this chip, as they are nearly impossible to find and expensive to replace. Now install an IC socket in its place. Repeat the test with no chip installed. If the short is gone, then the UDN chip needs to be replaced. If the short remains, then the display glass needs to be replaced.

Notes on different board revisions:
Williams also used the DI-0512 (Dionics-512) for the Digit Driver IC. I have owned the discrete transistor version, but the Dionics-512 version is even harder to find, and I've not seen one in 7 years of collecting. That's not to say they are not out there.
All the troubleshooting instructions above are intended for the UDN type boards, but the Dionics boards work in a similar way, so consult the schematics. You will also need to make sense of the warnings below.

'''Warnings:'''
These are factory changes, but if you replace or swap chips, you should be aware of the following
* The Display board must run similar chips, so for example all UDN-6118 / UDN-6184 types for the Digit Drivers OR all DI-0512 Digit Drivers (which are longer, meaning they have more pins). They have different power requirements! The two Segment Driver ICs need to match, too. So two MC14548 ICs at IC6 & 7, OR two MC14543 ICs at IC5 & 8. Mix & Match or having all four installed is mental (crazy)! You should have empty pads on the board for the optional IC chips.

* With the DI-0512 at ICs on these boards, the '10K' resistors R1-R14 are all 15K. Adjust the repair instructions below accordingly.
* If IC4 and IC11-14 are UDN-6118 chips, then a +100v trace is cut connecting pin 2 of connector J7 and ZR1 (1N4740A Zener diode) is added.
* With the DI-0512's this trace is left, and there is no Z1 used.

[[File:D8000-Cut-Trace.jpg|300px|thumb|left|Williams System 3-6 Master Display Board]] 
Sometimes a HV arc can occur between two pads on the Master Display board, and if this happens it will blow out the HV section of the PSU (power Supply Unit). If you have the UD7180 version of the System 3-6 Master Display board, it may be worthwhile taking this '''easy step''' to prevent a problem:

There is an unused track on the front of the board near to the bottom right corner of the Master display glass. The top round pad in this picture is unused on the UDN7180 version but goes to the +100v supply at Pin 2 of 4J7. Click to expand the picture at left for a better view.
 
It appears that the pad shorted out to the ground track that goes around both of the round pads. Cutting the track to the top round pad as shown in the picture (with the board removed from the game) will cause no problems for the displays on your game. And it could prevent disaster. A short could damage the HV section of the PSU, even the Master Display board itself. I have seen it happen, so better safe than sorry. BTW- This track '''should not be cut''' if the Dionics Digit Driver ICs are installed. The writer has owned many games and has never seen a board with the Dionics ICs.

==Sound / Speech Board Issues==
Sounds and speech are one of the most important parts of a pinball game for me.  Few things are more depressing for me than the sound of a pinball rolling around the wood with no background noises and without sounds of points being scored.

This section deals with the square sound board Type 2 ( System 6 & 7, with or without the speech "daughter card"). The Williams part number is 1C-2001-146-x, although much of the information applies to the Type 1 boards (System 3 & 4).
----
A description of the sound board Type 2:

* The sound board is actually a "mini-MPU" board running a 6808 CPU and a single 6821 PIA. So read the MPU board sections about the replacing sockets and the reset circuit as it will work in a very similar way.
* It has an external 6810 RAM for the CPU registers / 'stack'. This can be replaced by internal RAM in the 6802 CPU if that is used.
* It has it's own PSU (Power Supply Unit) and takes ~18v AC voltage directly from the games mains transformer and rectifies it to DC voltages that provide the +5v logic to the ICs and +12v for the CPU reset circuit.
* It provides -12v DC only used on the speech card for IC2 & IC3 the two 1458 OP Amps. They act as mixers for the analogue sounds and digital speech.
* A single 2K 2716 Eprom (ROM) which contains program instructions that 'boot' the CPU and code to create the sounds. Different ROM versions are containing specific sounds are numbered: Williams' Sound ROM 1, Sound ROM 2, Sound ROM 3...

The last item deserves some explanation. The Sound ROM does not store sounds as samples, but as mathematical 'strings' which describe parameters such as attack, frequency, decay and echo. So the board functions as a synthesizer, rather than playing a WAV file or compressed sound like an MP3 player today. In fact a 2K sample at 22K Hz sample rate could last about 1/10 of a second.

The 4K 2532 Eproms on the Speech Board can hold sampled sound but at very low quality. [[Black Knight]] used 4 Speech ROMs for a total of 16K and could speak about 20 words along with the famous laughter. Earlier games having 3 Speech ROMs Like Gorgar or Firepower could speak only about 11 words using 3 x 2532 ROMs.

'''Why did they provide a different PSU for the Sound card?'''
This early Williams game design could be for ground isolation, perhaps to provide a cleaner sound by avoiding interference from the other components which created RFI. Notice that I used "early Williams game design" and "cleaner sound" were just used together in the same sentence. I have also seen Sound Boards where the BR1 was missing and replaced by 4 x diodes, which also works. Two were mounted on the front and two on the back, with the bands on the diodes all pointing in the direction of TP1 (+12v). Start at 1N5401, rated 100v @ 3A.

Understanding this background should help pinpoint the source of problems with Sounds and Speech on games of the early 80's.

===Useful Sound Board Repair Links===
Leon Borre's work is a good starting guide for Williams sound board repair. He was a clever guy in Belgium, who developed special test ROMs for lots of pinball systems, including Williams System 3 through 7. ''' I can't thank him enough here!''' He developed a test chip that can be downloaded and burned to a 2716 Sound EPROM, which will start the CPU, "pulse" the PIA and also test the memory. It's harder to do any advanced fault repairs without this test ROM. So it's a good place to start if the sound board doesn't boot at all. Leon's technical article pertaining to Williams System 3 through 7 sound can now be found [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair here].

Dave Langley's site [http://www.robotron-2084.co.uk/techwilliamshardwareidsound.html robotron-2084.co.uk] has a clear diagram of jumper settings for most games on Williams Type 2 boards. Check jumpers first, W1 must be present if no speech board is attached.

===Testing for a Sound Board fault===
Before starting to repair a Williams sound card, first determine that there is actually have a sound board problem! Do the sounds work correctly from the sound board 'self test' by pressing the diagnostic button? Have you followed the diagnostic procedures in the game manual and checked the 'Solid State Flipper Maintenance Manual' or equivalent for the specific game? There will probably be a fault on the sound board if the diagnostic test on the sound board produces nothing (or the wrong sounds) '''and''' grounding the input pins won't work. See the 'sound selects' section for specific games below. Check out the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting section] first. After reviewing it, here are are some specific things to eliminate first:

* Bypass the volume control in the cabinet by removing the connector at IOJ4 and jumpering pins 1 & 2. It will be really loud (full volume in fact) so a couple K ohm resistor (3K?) looped around those two pins will substitute for the volume pot and save your ears.
* Take the sound board out, leave all the connectors still plugged in and the game running.
** The speaker and volume control can be set as above.
** Touch the back of the sound amp at IC1 with a finger - it's just under the Volume control connector J2 which was jumpered and has 5 legs. Not hearing this hum could be a missing +12v or a bad amp IC.
** A loud loud hum should be heard from the speakers, this proves the TDA2002 sound amp is working and also that the speakers are capable of producing sound.

Treat the sound board as a mini-MPU board (but with an on-board PSU) and all the usual fixes apply:
* Test there is around 18v AC coming in to the sound card. It's directly from the transformer to connector 10J1 and then fused with 2 x 8A fuses.
** Are both fuses good? Take them out and test them.
**Is the voltage getting further than the fuse clips? Are the fuses hot to the touch after the power is switched off? This may indicate high resistance at the fuse clips.
** Pin 5 of 10J1 is the 'center tap' or reference for the AC. There should be about 9.6 V AC between pins 1 and 5, and the same voltage between pins 9 and 5.
* Use the test points to measure DC +5v +12v and -12v. A short-cut (and much easier) is to touch the Red test lead to the left side leads of the 3 big capacitors, with the black lead on Ground which is the metal trace on the edge of the board.
**Remember -12v is only needed for the speech board, and even around -10v will normally be fine.
**Don't worry if the voltages aren't perfect (especially the +/-12v DC which is unregulated). Only the +5v needs to be in a narrower range (4.8-5.2v).
**No +5v with +12v present suggests the 1 amp '7805 5v regulator' at IC8 is faulty. It looks like the TIP-xxx transistor as it is in a TO-220 case, with a heatsink. Measuring +12v input on the top pin and no +5v output on the bottom pin will confirm this diagnosis. Obviously the CPU (and other ICs) can't run without the +5v logic voltage.
* If there are Scanbe sockets, replace them first, including the ROM socket. The PIA can be left alone for now if it's soldered directly to the board and not socketed.

Read the MPU board repair and troubleshooting if the board still won't 'boot' (the CPU, working RAM and reset circuit are very similar).
** Because there are no LEDs to show the board is 'locked up', you will need to look at pins 9 - 20 & 22-33 on the CPU for any activity with a logic probe. If the CPU has started, there should be some activity on these address and data bus lines. If they are 'dead', then the CPU has not started.
** If you look at the CPU bus lines with Leon's sound board test ROM (instead of the sound ROM) you can see which lines are missing, and also will see the PIA lines 'dance' as he calls it. The PIA I/O lines strobe Hi/Lo/Hi/Lo if they are working as they should. The test ROM will need to be burned on a 2716 Eprom.
** Review Leon Borré's [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair Williams sound board article] for advanced troubleshooting. You can fix boards more easily with his free test ROMs.
** Note: The the test chip will not start on a Type 2 board with jumper W1 missing, unless the speech card is also connected. Mine didn't start "pulsing" without the speech card. Because of this, here's a ''key tip'': '''Jumper W1, and set DS1: SW1 and SW2 to OFF and run without a speech board''' until the sound is working 100%. Do this now if you haven't removed the speech board already, it may not be obvious at first, but you have to get back to a basic setup and work forward from there.
See also [[Williams_System_3_-_7#Put the Sound/Speech Board on the Bench|Advanced Sound/Speech Board Repair on the Bench]]

===Back to Basics===
[[File:WMS_Sys6-7_Sound_W1_Jumper.JPG|left|300px|thumb|Temporary W1 jumper installed]]
[[File:WMS Sys6-7 Sound Pot Alternate.JPG|right|300px|thumb|Bypassing the volume control]] 
The next step, once you have verified voltages is to remove the speech board (if one is fitted) and jumper W1. Verify W1 is present for any board you are working on, as no sound gets to the audio amp without a speech board or jumper W1 present. 

To bypass the volume control, a 470Kohm resistor can be installed across pins 1 & 2 of connector 10J4. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped and installed in a .156" housing. Although a 470Kohm resistor is used in this example, other values can be used to obtain the desired volume. 470Kohms sets the volume to medium loudness. 

The .156" set up can be used on all Williams sound boards from System 3-7 games and 9-11 games too.
 

===Modification for Noisy Type 1 Sound Boards===
On the Type 1 sound boards, Williams did not use a small value bypass capacitor on the input to the 7805 +5V regulator as recommended by the manufacturer. This bypass capacitor is used to keep noise off of the +12V voltage rail, which is used by the power amplifier IC. Installing a .22uF ceramic capacitor across the input pin (pin 1 - left pin from front) and ground (pin 2 - center pin) of the 7805 regulator can significantly reduce the amount of noise and hum on these sound cards. Important note -- the Williams Type 1 Sound Board schematic diagram has an error. Pin 1 is the input, pin *2* is center pin and connected to ground and pin *3* is the output.

===System 4-6 Sound Selects===
Press the diagnostic switch on the Sound Board. When sounds do work on the sound board self test, but you get missing or incorrect sounds during a game, then a simple test for all models of sound card is to ground the input pins. This gives you an indication that the sound board is working, as each pin should produce a distinct sound. For Type 2 boards (square ones) that's 10J3 pins 2-4 and 7, pin 1 is on the right, It may also be the same pin locations on the Type 1 boards (Flash, and other System 3 & 4 games).

[[File:WMSType1SoundBoardBenchTestAnnotated.jpg|300px|thumb|left|Type 1 Sound board connections and grounding sound select header pins. Here, one end of a jumper wire is clipped to the ground plain of the board itself.]] 
Grounding those sound select pins is exactly what the Driver Board does during a game solenoid diagnostic test. It fires solenoids 9-13 to ground the select pins and this triggers 'sound calls' on System 3-6 games. If grounding the sound board pins works, then suspect cabling between the Sound Board and Driver Board or faulty transistors (or pre-drivers) on the Driver Board for the System 3-6a games. You can ground the transistor's metal tabs from the chart below, if this does not produce sounds then the cabling between Driver and Sound Boards is then suspected.

Please note that '''grounding the center tab of a transistor''' ''does not test the transistor(s)'', it only proves that the cabling from that tab out to the sound board select pins has continuity. It does not prove the transistor(s) work as a switch under the CPU's control.

This is true for '''''any testing of solenoids (or flashers) by grounding transistor tabs'''''. It only proves that the cabling from the Driver Board out to the device is intact, and that the device has power and can function when grounded.

So the Solenoid portion of the diagnostic test will help you figure it out for a System 3-6 game. It can perhaps help for System 7 game too, although remember that sound calls are triggered from the MPU board instead. 

On System 6 (and earlier) you will have a fault on the Driver Board, and specifically the solenoids in the range 9-13 if the following are true:
* The self test on the sound board works as expected,
* Grounding tabs on the Driver Board produces the same sounds,
* But the game's diagnostic tests do not trigger sounds when testing solenoids number 9-13.

If it fires the device, the problem is the transistors or the logic on the driverboard and then the PIA upstream from them. You should first replace both the associated TIP 120/102 and the matching 2n4401 pre-driver transistors on the Driver Board (a fairly easy fix) and re-test. Then follow Driver Board testing and repairs.

If a transistor gets shorted 'on' (or a 7408 IC is faulty) and one of the sound selects is constantly grounded from the Driver Board, you will certainly get fewer and usually wrong (or no) sounds played. This type of problem can be chased around for hours, if you don't work logically through the problem.

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="25%" border=2
|+'''Driver Board Positions'''
|-
| 2J9 ||10 || 9 || 6 || 7 || 8
|-
| 2J9 ||11 || 12||13 || 14 || 15
|}

Blue shows the 5 Sound Select Transistors on the bottom two rows of a System 3-6(a) Driver Board.

If diagnostics don't work as you expect, as explained, ground the metal tabs of the TIP122 transistors (briefly - they may be real coils or flash lamps!) on the bottom 2 rows of the driver board. You should hear 5 different sounds. The first 3 sound select transistors are at the bottom left of driver board. The first two the next row up are the remaining sound select transistors (solenoids 9-13 as shown on the chart above).

You can of course also '''turn off the game''' and measure between the center tab and the input pins on the sound card with an DMM (meter set on continuity or Ohms). If you get high resistance readings, check for cold solder joints on the input pins of the sound board at 10J3. Then check the output pins on the Driver board at 2J9. Reflow the solder on all these pins. Do the other pins on the sound board at the same time.

Another tip is that you should see the center tab of the Blue "sound transistors" running at about +5v DC on the driver board with the game running. If a tab is at zero volts, and others are at +5v then that grounded select points to the problem. Other TIP122 transistors could be at the coil potential, so have your DMM set to voltage and +50v or above for this test if it does not 'auto-range'.

If you get this far and can get 5 distinct sounds, then the problem is not the sound board, nor the connection to the driver board. With System 3-6, this could still be on the driver board and specifically:
* a power transistor TIP122,
* a matching 2n4401 pre-driver transistor ,
* a 7408 logic IC
: and finally
* a 6821 PIA for Solenoids at IC5. As this is a 40 pin IC, it should be replaced as a last step.

At this point just follow the driver board testing and repair guide to get further.

Complete list of Driverboard 2J9 pins and the associated transistors (for Sys3-6) are:

{| cellspacing="0" cellpadding="3" width="50%" border="2" bordercolor="#0"
|+'''System 6 Driver Board 2J9 Sound Outputs'''
|-
| Pin
| Sol.
| Function
| Transistors
| Wire Colour
|-
| 2J9 P9
| # 9
| Sound Select 0
| Q31 / Q30
| Brown / Black
|-
| 2J9 P8
|  (*)
| Key
| 
| N/C
|-
| 2J9 P7
| #10 
| Sound Select 1
| Q33 / Q32
| Brown / Red
|-
| 2J9 P6
| #16
| Coin Lockout*
| Q45 / Q44
| Brown / Grey
|-
| 2J9 P5
| #15
| Depends on game*
| Q43 / Q42
| Brown / Violet
|-
| 2J9 P4
| #14
| Credit Knocker*
| Q41 / Q40
| Brown / Blue
|-
| 2J9 P3
| #13
| Sound Select 4
| Q39 / Q38
| Brown / Green
|-
| 2J9 P2
| #12
| Sound Select 3
| Q37 / Q36
| Brown / Yellow
|-
| 2J9 P1
| #11
| Sound Select 2
| Q35 / Q34
| Brown / Orange
|}

* Typical functions, but depends on the game.

List of J3 sound select pins on the System 6 or 7 sound board are:

{| cellspacing="0" cellpadding="3" width="50%" border="2" bordercolor="#0"
|+'''System 6/7 Sound Board Inputs'''
|-
| 10J3 Pin
| Sol.
| Function
| Wire Colour
|-
| J3 P3
| # 9
| Sound Select 0
| Brown / Black
|-
| J3 P2
| #10 
| Sound Select 1
| Brown / Red
|-
| J3 P5
| #11
| Sound Select 2
| Brown / Orange
|-
| J3 P4
| #12
| Sound Select 3
| Brown / Yellow
|-
| J3 P7
| #13
| Sound Select 4
| Brown / Green
|-
| J3 P1
|  (*)
| Key
| N/C
|}

On System 6, using only 5 solenoids for sound limits the number sound and speech calls. Makes 25 = 32 so only 31 usable combinations, a call of all 0's being null. But (using Firepower as an example) you then can have all the combinations of maybe 20 sounds plus the 11 speech phrases it "knows". So it's enough given the small amount of sound and speech memory they had to work with at the time. In fact it's amazing! For more background, see: An interview with [http://www.firepowerpinball.com/downloads/Eugene_Jarvis_Interview.pdf" Eugene Jarvis], the sound engineer and programmer for Williams at the time.

Changing the sound board won't cure the problem of a missing solenoid signal, and a major clue is that the sound board tests good, and is also good when grounding the 5 input pins at (Board #10) J3 input connector on the sound board.  While the "in game" sounds or game diagnostics will play incorrectly or have missing sounds. For example, an email from someone said that their Firepower game could say "Power" but not "Fire"! A fairly easy diagnosis if you know the game, it pointed to transistor Q35 (a TIP122, a better replacement is the TIP102) which was completely missing from the Driver board. Transistors on the bottom row often get bent back and forth and snap clean off - hard to spot if you aren't familiar with inspecting the Driver Board.

That transistor's center tab connects to 2J9 pin1 and solenoid 11 then fires sound select #2, according to the table above. Without that sound select being triggered, only half the game sounds could be produced (24-1> = 15). "Fire" was one of the missing sounds, there were others but they may have not been so obvious to the owner. They would not be listed in the manual as a sound triggered by an achievement (making to rollovers F-I-R-E in this case). The point is to use all the information available to help determine the root cause of your fault.

===System 7 Sound Selects===
By System 7, Williams had stopped using solenoids to fire sounds and had added a dedicated Sound/Comma PIA on the CPU board to trigger sound/speech. This meant more playfield coils and even flash lamps were now possible, as the Driver Board wasn't used to trigger the Sound Board.

On a Black Knight and later games, the fault could still be on the MPU board. Perhaps PIA 5 (IC36 a 6821 PIA) is suspect as this drives the sound board (and display commas) only. Again you can trigger sound selects by grounding pins on the sound board, and then move back to the header pins of the MPU at 1J8. The pins are12,11,10,9,8 in that order for the 5 sound selects 0-4

The outputs of the IC36 PIA at PA0-PA6 connects to 1J8 starting at pin 12 (1J8 P12) and run backwards numbered as the Sound Selects in the table below:

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="25%" border=2
!colspan="3" |'''SYS 7 1J8 Sound & Comma Outputs'''
|-
! Pin
! Function
! Wire Colour
|-
| 1J8 P1 || Comma 3 & 4 || Brown / White
|-
| 1J8 P2 || Comma 1 & 2 || Violet
|-
| 1J8 P3 || Key (*) || N/C
|-
| 1J8 P4-7 || No Connection || White
|-
| 1J8 P8 || Sound Select 4 || '''Yellow'''
|-
| 1J8 P9 || Sound Select 3 || Green
|-
| 1J8 P10 || Sound Select 2 || Blue
|-
| 1J8 P11 || Sound Select 1 || Red
|-
| 1J8 P12 || Sound Select 0 || Red / '''Yellow'''
|}

In theory Williams had the ability to trigger Sound Selects 0-6 from the System 7 MPU board, and could have programmed 127 sound / speech calls. But the sound boards at the time never used that many, to my knowledge. So you only need to worry about the same 5 sound selects 0-4. Be sure to first '''''check the output pins at 1J8 on the MPU Board for cold solder joints''''', before replacing the 40 pin PIA.

===Put the Sound/Speech Board on the Bench===
By this point, it is likely that there is a sound board fault. If you don't feel comfortable troubleshooting or don't want to get involved with low level board repairs, there are repair services available--check pinball communities/forums for recommendations. [[Williams_System_3_-_7#If All Else Fails|Reproduction sound and speech boards]] are also available if all else fails.

[[File:WMS Sys6-7 Sound Pinouts.JPG|300px|left|thumb|WMS System 6/7 Sound Board Pinouts]] 
If none of this helped so far, read the rest of the section below. The boards will likely need to be bench tested in order to proceed with testing. Any PC power supply has the +12v and -12v DC that will be necessary for bench testing, which are normally located on the motherboard connectors. The older the PC power supply, the better, as they will have a power switch, but there are two pins that can be jumpered (or connected to a switch) to enable the voltage outputs.
 

[[File:WMS Sys67 Sound Bench.JPG|300px|left|thumb|WMS System 6/7 Sound Board Connected to an AT Power Supply]]
[[File:WMS Sys67 Sound Test Points.JPG|300px|right|thumb|WMS System 6/7 Sound Board Connections for an AT Power Supply (Four Sound Board Test Points)]] 
Search for an "AT Power supply" on the web for the connector locations or measure them with the DMM. The wires on one example were colored Yellow (+12v) and Blue (-12v). Ground was black as usual. Sliding the existing pins from the motherboard connector housing, and they will potentially fit right in a .156" socket to connect to the sound board. The +12 and -12 goes to the outsides of a 9 pin connector (pins 1 & 9) and the ground to the center pin (pin 5). It doesn't matter which way around the connector is installed--if the Bridge Rectifier (BR) is working it will sort it out by conducting through the correct diodes. 

Another method is to connect the AT power supply connections with alligator test leads directly to the four test points on the sound board. However, this method will not ensure that the bridge rectifer on the sound board is working or not.
 

At this point refer to [[Leon_Borre_Williams_Early_Sound_Repair|Leon Borre's sound board test link]]. He has an excellent approach to a sound board that is dead. A copy of his sound test ROM will need to be burned to an EPROM. A logic probe (under $20) will also be needed, but Leon describes how to make an LED test probe with some wire, an LED, and a resistor which costs a few cents. The logic probe will be more versatile and easier to use. As mentioned before, the Test ROM can check the CPU, memory and also exercises the PIA inputs/outputs. An added bonus is that the test ROM will allow the board to boot, even though there are faults on the board.
 

===Checking for Sounds Prior to the Sound Amplifier===
[[File:WMS Sys6-7 Sound Preamp Probe.JPG|300px|left|thumb|An unamplified speaker used to probe for sounds before the sound amplifier]]
A method to test for sounds prior to the amplifier is to check the output of the D/A converter. This can be accomplished by building a speaker set up. It starts with a low wattage speaker, which does not need amplification to produce sounds. A speaker from an old computer case is a great source. After acquiring a speaker, solder two wire leads to it. Then, solder an alligator test clip to one of the leads, and a small piece of solid, copper, house wire (14 or 12 gauge romex works well) or a small finishing nail to the other lead. The second lead will be used to probe the sound output before amplification. This speaker test set up can be used on any other brand sound board too. 

After the speaker test set up is constructed, clip the alligator test lead to ground. Then, place the probe lead on the "C" collector leg / solder pad of the Q2 transistor, as shown in the picture. Once the probe is in place, press the sound board test button. The speaker will have to be placed close to one's ear to hear the sounds, if any sounds are being output. If the sounds are being heard, either the amp (IC1 - TDA2002) has failed, has lost connection (cold solder joints), or is not being powered properly. 

Normally the probe would be used to check the sound output right on the leg of the D/A converter (IC13 - 1408). However, pin 4 of IC13 (the output) is adjacent to pin 3, which inputs the -12vdc power to the D/A converter. It is much safer to use the collector leg of Q2 as a probing point to avoid shorting pins 3 and 4 together. 

Note that the if the 1408 DAC has failed, it can be subbed with the more readily available DAC0808.
 

===Getting Sound and Speech Working Together===
The very first thing is to make sure you have the correct jumper settings and ROM types.  You can NOT "mix and match" sound and speech ROMs as you like.

My experience is on Williams System 4-7 pinball where the Sound ROMs are 2716 Eproms and the Speech are always 2532 Eproms. The exceptions are video games (and a few pinballs), such as Defender, Sinistar, Robotron and Joust which use a 2532 on the sound board ROM and each has special jumper settings.

'''You need the correct Sound ROM type for your game's Speech ROMs'''.

Firepower '''and''' Alien Poker both use "WMS Sound ROM 3" no matter '''what''' the Alien Poker manuals (or ROM download archives) say. It's the only way I ever got speech to work on my Alien Poker. If you have [[Blackout]], you will need a 2716 Sound ROM 2 to go with Blackout's 2532 Speech ROMs.

This is mainly a warning if you will be plugging together different boards on a workbench or when troubleshooting a problem, don't trust that all Sound ROMs work with all speech boards !

Here is a diagram on placement of the Speech ICs, as the layout of the ROMs aren't very logical. Check they are correct. This diagram works for any of this type of Speech Daughter board. Replace your game number nnn in ST-nnn-ROM# format.
See examples for [[Firepower]] (497), [[Alien Poker]] (501) and [[Black Knight]] (500), which are among my favourites.
The information is provided for clarity, it is recommended that you replace Original Speech Mask Roms with newer 2532 Eproms. 

'''Note:''' unless a System 9 speech board is available with jumpers, 2732 Eproms cannot be used for the speech board, unless the board is [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified].

'''Speech ROM IC socket locations:'''
[[File:Speech-ICs.jpg]]

Also distrust the switch settings and be aware that you could have a faulty DIP switch on the Type 2 board. It can happen! Test by removing the 2-way switch, or jumpering across the back of the switch. If DS1-2 is not connecting, you will hear sounds- but no speech.

The clue here is that if you press the sound board diagnostic switch, you hear BOTH sounds and speech.
[[File:WMS Sys67 Speech Scanbe.JPG|300px|left|thumb|System 6/7 Speech Board with Scanbe Sockets]]
[[File:WMS Speech Scanbe Socket.JPG|300px|right|thumb|Identifying Scanbe Sockets]] 

: Speech ROMs and Speech Board sockets should eliminated, you can measure continuity on all pins from the Speech ROM to the bottom of the socket or back of board before replacing Sockets. If they say '''SCANBE''' then replace them as they will be faulty.
: Gaps in speech usually point to a faulty Speech ROM, look in the manuals for which ROMs hold the missing words.
: Suspect the logic selects on the sound board or the 40-way IDC connection between the speech board to the sound board. Watching for 'chip select' pins 20 on each Speech ROM with a logic probe will help you see the chips being selected by the sound board. Again knowing which ROMs hold the missing phrases will help. No speech selects can point to the interboard cables, or missing outputs from IC2 (a 7442 decoder) '''on the Sound Board'''.
:Bear in mind that the Speech card is an 'expansion board' to hold ROM space for the speech and the digital/analogue mixer. The address and data buses extend across the '40-way' IDC connector in a similar way to the connector between the MPU and Driver Board. Except the connector solution is more robust and IDC was still used until recently to connect IDE PC hard drives.
 

Other problems that could cause sounds but missing speech include:

* W1 is jumpered,
* W9 is NOT jumpered (W4 is probably in place),
* IC7 (inverter) faulty,
* IC10 (6821 PIA) is faulty (use Leon's Sound Board test chip)
* Faulty speech board (no speech) or speech ROMs are installed incorrectly

Switch 2 MUST be ON for speech. OFF for no speech.

Switch 1 selects between Tones and Synth Sounds.
ON for musical tones (more like bings and bongs),
OFF for Synthesized Sounds.

{| bordercolor="#0" cellspacing="0" cellpadd ing="3" width="10%" align="left" border=2
| SW 2
| ON
|-
| SW 1
| OFF
|}

    '''DS1 Set correctly for Sounds and Speech.'''
 

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="10%" align="left" border=2
| SW 2
| OFF
|-
| SW 1
| OFF
|}
     '''DS1: Set for Sounds only.'''

     You will also have to '''jumper W1''' if this is not in place.
 

==Speech Board Issues==
===Common failure parts===
[[File:System7SpeechBoardBefore.jpg|left|thumb|300px|Speech board sockets. These are Molex, but "they gotta go".]]
[[File:System7SpeechBoardAfter.jpg|right|thumb|300px|Nice twin wipe sockets, which are preferred over machine pin sockets.]] 
The first and most important action when debugging a Speech board is to eliminate all of the common failure issues. With these issues out of the way, it is much easier to focus on the real issues preventing proper operation. And, eliminating these typical trouble areas almost always brings the board back to full operation.

The most frequent reason for failure of the speech board are the OEM sockets. ScanBe sockets, or white sockets pictured here, should be replaced. If a ROM can be easily removed using only your fingers, the socket should be replaced.

Also check the ribbon cable to the sound card. It breaks frequently at pin 1 which carries the 5V Analog voltage. If you replace the cable make sure that you do not damage the J1 connector. The part is either NLA or so obscure no one stocks it. Fortunately you can gently pull off the cover and reuse it with a new cable. The counterpart is a standard ribbon connector and must be replaced. 

If your speech is garbled and you replaced the MC1458 chips the 55516 CVSD at location IC1 might be bad. This is somewhat rare but not unheard of. The part is long since obsolete and hard to source. It can be replaced with a 55532, 55536 or 55564. Only the 55564, which was used up to the Williams WPC era, seems to be somewhat available. Check your favorite pinball shop for it. 

As with all electronics other parts can fail but the above parts are responsible for around 95% of all speech card failures.
 

===Using the Sound Board Test ROM===
Leon's test ROM and instructions will be very useful. The ROM and instructions are available [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair here].

Note: The the test chip will not start on a Type 2 board with jumper W1 missing, unless the speech card is
also connected. Mine didn't start "pulsing" without the speech card. You also need
to put the Test code on a 2716 Eprom.

Here's a key tip: Jumper W1, and set DS1: SW1 and SW2 to OFF and '''run without a speech board''' until the sound is working 100%. Do this now if you haven't removed the speech board already.

This may not be obvious at first, but you have to get back to a basic setup and work forward from there.

The following is an attempt to list notable Williams games that used these boards.

There are conflicting lists, Hyperball could be a 2532 ROM #8. as the file hypsnd12.532 has a checksum of 0x25A8 - which doesn't match other sound ROM images. So the list is not perfect. Some corrections have been as of Feb 2011 after more research. If you have updates or can confirm Williams sound ROM numbers (and compared checksums) then please go ahead and edit this table.

The games with speech in the first table are right, I'm less happy with the Video games and Hyperball.

Williams Pinball Games which use a Type 2 Sound Board and a Speech Board:
{| cellspacing="0" cellpadding="3" width="50%" align="left" border="2"
!NAME
!SYS
!GAME
!WMS SOUND ROM
|-
| Blackout
| 6
| 495
| Sound ROM 2 
|-
| Gorgar
| 6
| 496
| Sound ROM 2
|-
| Firepower (r)
| 6
| 497
| Sound ROM 3
|-
| Black Knight(r)
| 7
| 500
| Sound ROM 5
|-
| Alien Poker
| 6a
| 501
| Sound ROM 3 confirmed
|-
| Jungle Lord
| 7
| 503
| Sound ROM 3
|-
| Pharoah
| 7
| 504
| Sound ROM 6
|}
 

(r) Steve Ritchie Game Design

Video Games with Sound and Speech Board:
Sinistar (cockpit front) & Upright, Type 2,VIDEO ROM 9

Pinball Games with Sound Boards Only:
{| cellspacing="0" cellpadding="3" width="50%" align="left" border="2"
! NAME
! SYS
!GAME
!WMS BOARD, SOUND ROM
|-
|Flash (r)
|4
|486
|Type 1 Board, ROM 1*
|-
|Time Warp
|6
|489
|Type 1 Board, ROM 1
|-
|Stellar Wars (r)
|4
|490
|Type 1 Board, ROM 1
|-
|Laser Ball
|6
|493
|Type 1 Board, ROM 2
|-
|Scorpion
|6
|494
|Type 1 Board, ROM 1
|-
|Algar
|6a
|499
|Type 1 Board, ROM 4
|-
|Cosmic Gunfight
|7
|502
|Type 2 Board, ROM 12
|-
|Solar Fire
|7
|507
|Type 2 Board, ROM 7
|-
|Hyperball
(n)
|7
|509
|Type 2 Board,
SPECIAL ROM 8 ?
|-
|Barracora
|7
|510
|Type 2 Board, ROM 4
|-
|Time Fantasy
|7
|515
|Type 2 Board, ROM 13
|-
|Warlock (pin)
|7
|516
|Type 2 Board, ROM 14
|-
|Defender (pin)
|7
|517
|Type 2 Board, ROM 15
|-
|Joust (2 player pin)
|7
|519
|Type 2 Board, 
SPECIAL Snd_IC12.532 ROM
|-
|Laser Cue
|7
|520
|Type 2 Board, ROM 3
|-
|Firepower II (m)
|7
|521
|Type 2 Board, ROM 13
|-
|Star Light **
|7
|530
|Type 2 Board, ROM 3 
ROM 4 is on my game!
|}
 

(r) Steve Ritchie Game Design

(m)  Mark Ritchie Game Design

(n)  Not a Pinball, a gun game that shoots tiny pinballs.

* Sound ROM 1 was used from World Cup #481 to Scorpion #494, but not Laser Ball from my notes.

** Quite a rare and beautiful pinball. Only 100 were produced, the last Williams System 7.

Here is some useful [http://pin-logic.com/early_williams_pinball_game.htm pinball sound file checksum] information. At [http://pin-logic.com Tom Callahan's pinlogic.com]

{| cellspacing="0" cellpadding="3" align="left" border="2"
!NAME
!WMS BOARD VIDEO ROM
|-
| Bubbles
| Type 2 Board, VIDEO ROM 5
|-
| Defender (Video)
| Type 2 Board, VIDEO ROM 1
|-
| Joust (Video)
| Type 2 Board, "VIDEO" ROM 4 
(Checksum matches ROM 4 from Algar and Barracora)
|-
| Robotron 2048
| Type 2 Board, VIDEO ROM 3
|-
| Sinistar (cockpit rear)
| Type 2 Board, VIDEO ROM 10
|}
 

Please Note: VIDEO ROMS and those for Joust (a 2 player head to head pin) and Hyperball are 2532 Eproms

An annoying fact is that from around System 7, most of the WMS sound ROM files are all named something like '''SND_IC12.716 ''', which makes them harder to identify.

===Running a Type 2 Sound Board with a 6802 CPU===
You might not have an 6808 CPU, or you might upgrade to a 6802 because then there is one less IC (the 6810 RAM) to go wrong. You can leave the 6810 (as it's not socketed) if the card functions with it in place.

You can get the Type 2 board to run on a 6802 CPU, without a working 6810 RAM in IC11. To do this you cut a track called W14. It isn't a 0 ohm resistor (or a real jumper), it's a track located under R30, the 3rd resistor in from Left on the Bottom Left of the board. W14 grounds pin 36 of the processor for a 6808 CPU.

If you want to use a 6802, you cut the track W14. Pin 36 will go high through the 4.7K "pull up" resistor at R30. You could then remove the 6810 RAM as the 6802 has internal RAM. My advice is again to just '''''leave it in place''''' if the card functions with it there. I had to rework tracks damaged by removing a 6810 on one sound board being repaired. Avoid making extra work for yourself, and '''''spend more time playing pinball'''''. That way it can be reverted back to 6808 operation in future. Good instructions are currently at [http://www.robotron-2084.co.uk/techwilliamshardwareidsound.html www.robotron-2084.co.uk]. A useful site for arcade video and pinball and Dave has a nice Defender pinball to look at while you're there.

===Modifying the System 6/7 Speech Board to Use 2732 EPROMs===
The original System 6/7 speech board is setup to only use 2532 EPROMs. With the following simple modifications, a speech board can use 2732 EPROMs instead, if the need arises. Please be aware that although these modifications are reversible, it is not nearly as easy to change a modified board using 2732 EPROMs back to a board which uses 2532 EPROMs. 

Procedure:

#On the component side of the board, there is a trace which runs beneath the ribbon cable connection and between pins 11 and 12 of U5 (the lowest two pins on the left). Cut this trace.
#Turn the board over to the solder side. The orientation of the board in the pic below is with the ribbon cable connection on the right.
#Locate pin 18 of U5. There is a trace between pin 18 of U5 and a via down and to the right of it. To verify the correct via, check continuity between pin 13 of the ribbon cable (fourth pin up on far right of the ribbon connections) and the via. Cut the trace between this via and pin 18 of U5
#There is another via slightly down and to the right of the previously discussed via. This second via will have continuity between it and pin 12 on the ribbon cable (third pin up on far left of the ribbon connections). The via will also have continuity between pin 21 of U5. Using wire wrap or a thin gauge wire, tie these two vias together.
#Locate pin 18 of U5 and pin 12 of U4 (down and to the left of U5 pin 18). Again using wire wrap or a thin gauge wire, tie pin 18 of U5 to pin 12 of U4.

<center>
<gallery widths=300px heights=300px perrow=2 caption="System 6/7 Speech Board 2732 EPROM Modification">
File:WMS Sys67 Speech 2732 Mod Front.JPG|<center>Trace cut on component side</center>
File:WMS Sys67 Speech 2732 Mod Back.JPG|<center>Trace cut and two jumpers added on solder side</center>
</gallery>
</center>

 

===Replacing the on-board volume control with a remote volume pot (System 4)===
[[File:DSC0760.jpg|300px|thumb|left|System 4 original volume pot]]
[[File:DSC0761.jpg|300px|thumb|right|Connector 10J4, with pins 1 & 2 bridged with solder.]] 
If the volume pot on your system 4 or later sound board fails or otherwise needs replacement, it's often difficult (or impossible) to find a direct matching part. In such cases adding a remote volume pot may be the only solution. 

The first thing to do is flip the board over and make sure that somebody hasn't bridged pins 1 and 2 of connector 10J4, as shown here. If it has been bridged, remove the solder bridge and solder the pins independently to the board. 

[[File:DSC0762.jpg|300px|thumb|left|Taking a reading across volume pot legs.]]
[[File:DSC0763.jpg|300px|thumb|right|Taking a reading across volume pot legs.]] 
Take a resistance reading across the existing volume potentiometer's legs. If you get a reading above 4K ohms, the potentiometer is not mostly shorted and will not require its leg to be cut as detailed below. (i.e. you may skip that step below.) 

This potentiometer is not mostly shorted and could be left un-cut. 

[[File:DSC0764.jpg|300px|thumb|left|Cutting the volume pot's left leg.]]
[[File:DSC0765.jpg|300px|thumb|right|After cutting volume pot's left leg.]] 
If the previous resistance reading reads less than 4K ohms, then one leg of the potentiometer '''must''' be cut. (This one was cut for the sake of demonstration.) 

After the cut, the potentiometer should look similar to this. 

[[File:DSC0766.jpg|300px|thumb|left|Jumper added across volume pot legs.]]
[[File:DSC0767.jpg|300px|thumb|right|Replacement potentiometer.]] 
'''In all cases, a jumper must be added to the back side of the board to bypass what is left of the old potentiometer.''' 

A new 5k-ohm, audio (logarithmic) taper potentiometer must be sourced. 

[[File:DSC0768.jpg|300px|thumb|left|Wiring of new potentiometer.]]
[[File:DSC0769.jpg|300px|thumb|right|Wiring of 10P4.]] 
Here a radio shack 271-1720 potentiometer was used. 

Three wires must be run between the potentiometer and 10P4, the plug that connects to 10J4. The wires must then be connected to 10P4, as shown. 

Plug the new 10P4 into 10J4, and the on-board volume pot will be bypassed with the new external pot. 

===If All Else Fails===
You can source a replacement sound/speech board. It may be more cost effective than sending out your sound boards to be fixed, especially as you may be able to sell the original boards to get back some of the initial outlay. These are good quality products, the price isn't bad and they should last for many years to come. James Kohout's [http://www.pinballpcb.com pinballpcb.com]

==Solenoid Problems==

===Controlled Solenoids===
[[File:WMSPharoahExtraGround.jpg|300px|thumb|left|In addition to the ground braid being screwed to this post, a white wire with red stripe is also connected.]] 
Some Williams games provide ground for coils via an extra wire (white/red) that must be connected to the backbox ground stud as shown in the picture at left. If this wire is not connected, some coils will not work. An example is Pharaoh, which uses this path to ground for both "Magna Save" magnets and the hidden tomb coils.

Note: in the example picture, a nut has been used to replace the typical "wing nut".
 

====Special Note Regarding Coin Lockout Coil and Free Play====
When some games (perhaps all games but at least Flash using Green ROMs) are set on "free play", by setting adjustment 18 to zero, the coin lockout coil will not be turned on. This makes sense since when free play is enabled, coins should drop straight through the coin mech and into the coin return.
 

===Special Solenoids===
[[File:WMSSystem3-7SpecialSolenoidDrives.jpg ‎||left||thumb||300px||A closeup of the special solenoid circuitry showing transistors Q2 through Q12. Note that these transistors are not numbered row and column sequentially. Argh!]]
[[File:WMS3-7SpecialSolenoidDiagram.jpg ‎||right||thumb||300px||Diagram of Williams System 3-7 Driver Board Special Solenoid Section]] 
The Special Solenoid drives switch power to ground for pop bumpers and sling shots. This "special" circuitry was implemented with the thought that the switch matrix could not be polled rapidly enough for these devices to be highly responsive. The drive transistors can be switched on either by a switch closure on the device, or under software control by the CPU.

The Special Solenoid drive transistors, Q2 through Q12, are located just above the flipper power ground enable relay Z1.

The flaw in this circuitry is that a "one shot" was not implemented (ala Gottlieb System 80 Pop Bumper Driver Boards). One shot circuitry only allows the associated solenoid to engage once per switch closure. In the case of the Williams special solenoids, as long as the switch is tied to ground, the solenoid will be engaged. As long as a device switch (pop bumper or sling) is closed, then coil power will be switched to ground continuously, eventually overheating and killing the associated TIP-122 (or TIP-102) transistor and / or the solenoid.

There is also a lack of "intelligence" in the software as was implemented eventually in WPC games. WPC games disable a device if the device's associated switch is sensed closed 10 times in succession without sensing any other switch closure.
 

====Arc Suppression Resistor/Capacitor for Special Solenoids====
See also: [[#Wetting_Current_Resistor.2FCapacitor_for_Special_Solenoids|Wetting Current Resistor/Capacitor for Special Solenoids]]

While a certain amount of current is necessary to help keep contacts clean, too much current can result in arcing when a switch is opened, which over time, can cause pitting and erode the contacts. To prevent this, an RC network is placed across the contacts.

When the contacts in an arc suppression circuit open, the applied voltage is placed across the capacitor and not the contacts.

The capacitor charges at a rate faster than the contacts open which prevents an arc from forming across the contacts.

When the contacts close, the inrush current from the charged capacitor and source can be substantially higher than the contacts can safely conduct, causing the contacts to deteriorate. This is why it is important to have a resistor in series with the capacitor.

The resistor acts as a current limiter which reduces the inrush current by a significant amount. The arc produced at the contact closure is greatly reduced, thus extending the service life of the contacts.

Reference: https://testguy.net/content/362-Arc-suppression-circuits

====Wetting Current Resistor/Capacitor for Special Solenoids====
[[File:System4SpoonSwitch.jpg ‎||left||thumb||300px||A resistor/capacitor connected across a pop bumper spoon switch.]]
[[File:RCNetworkSystem4.jpg ‎||right||thumb||300px||The schematic for the circuit as implemented for slingshot switches.]] 
Williams used a 22uf capacitor and a 100ohm resistor, themselves connected in series, wired across special solenoid switches to provide a minimum "wetting current" across the switch contacts. This implementation also provides some measure of "electrical debouncing" of the switch. In the image at left, the black wire is coil power from the power supply. The orange wire is the path back to ground via a driver board special solenoid drive transistor. The green and white wires are switch matrix wires for the "scoring switch". A 1N4004 switch isolation diode is used just like any other switch matrix switch.
 
See: https://en.wikipedia.org/wiki/Wetting_current

The special solenoid switch contacts are pulled high to 5 VDC through a 4.7K ohm resistor on the driver board. When the special solenoid switch closes, this voltage is shunted to ground resulting in a current through the contacts of approximately 1 mA. This very low "wetting current" is insufficient to keep the contact surfaces clean and free from dirt and oxides. An RC network is placed across the contacts to increase the wetting current and help break through any dirt or oxidation that has formed on the contact surfaces. When the contacts are open, the capacitor charges to 5 VDC through the 4.7K and 100 ohm resistors in series. When the contacts close, the capacitor discharges through the contacts and the 100 ohm resistor, resulting in a momentary peak current of approximately 50 mA. This discharge wetting current is sufficient to burn off any surface film that has built up on the contacts. Once the contacts open again, the capacitor begins charging again and effectively extending the contact closure time. This also provides some amount of electrical debouncing.

 

==Lamp Problems==

===General Illumination Lamps===

[[File:WMSSystem7PowerSupplyBurn.jpg||left||thumb||300px||An extreme example of high current damage to the general illumination traces of a System 7 power supply.]] 
One of the largest weaknesses of the System 7 board set (starting with the later run of Black Knight) is the general illumination PCB connection. The configuration of that connection evolved from a two pin Molex connector into four (two for AC in, two for AC return) 18 gauge wires soldered directly to the board and connected to the transformer secondary with a 4-pin Molex connector.
 

===Controlled Lamps (Lamp Matrix)===

One source of problems with the lamp matrix can be the 27 ohm 3 watt resistors used for the lamp columns. These resistors put out a '''ton''' of heat! In some extreme instances, they can get so hot that they will literally melt the solder which holds them to the driver board, and fail off the board. It is best to replace these resistors with 27 ohm 5 watt resistors. The 5 watt variants can dissipate the heat a little better. When replacing these resistors, make certain to allow enough space under them to allow for air cooling. Even though it is best to use higher wattage resistors, they still put out a fair amount of heat.

<center>
<gallery widths=200px heights=350px perrow=4 caption="Williams System 3-7 Driver Board Lamp Matrix Resistors">
File:Wmsdriver_heatdamagedresistors.jpg|<center>Old resistors in questionable condition due to overheating. Note these are 3 watt resistors as shipped by WMS. Later boards used 5 watt versions.</center>
File:Spacer WMS Lamp Resistors.JPG|<center>Using a pencil to allow proper spacing of the resistors from the driver board. One by one, place the legs of the resistors through the circuit board, and bend the legs over.</center>
File:Spacer WMS Lamp Resistors Back.JPG|<center>Flip the board over, and allow the resistors to "hang" off the board.</center>
File:Spacer WMS Lamp Resistors After.JPG|<center>New resistors soldered on the board with ample air flow beneath them.</center>
File:ResistorRaising.jpg|<center>Another method of raising the resistors. Be sure to remove the cardboard when complete.</center>
File:WMSSystem3-7LampMatrixResistorsRaised.jpg|<center>Side view of resistors raised with ample air flow beneath them.</center>
</gallery>
</center>
 
====Testing the Lamp Matrix====

This is a generic [[media:13-lampwiring.pdf|Lamp Matrix Diagram]] which you can refer to for testing the lamp matrix.

====Reducing heat by replacing the TIP-42 lamp drive transistors and eliminating the 27 ohm current limiting resistors====

The original Williams (and Data East) lamp matrix circuitry dissipates a lot of heat through the 27 ohm current limiting resistors. Often, this part of the circuit board is badly heat damaged. The TIP42 transistors are bipolar PNP transistors, and require a lot of drive current on the base. The current through the 27 ohm resistors does not even go to lamps, just to the base. The issue starts when the 40 pin interface connector becomes faulty. If the lamp scan update is not received by the driver board, it will sit on one selected column of lamps.. and promptly burn one 27 ohm resistor off the board, possibly burning a hole in the board.

The first method below is simpler to implement, but the second method is included, as it has been implemented for many years.

In the first upgrade method, replace the 8 TIP42 transistors with the darlington version, which require much less current. Get 8 TIP125 transistors, and replace the 8 original transistors, being careful to keep them oriented the same way. Masking tape can keep all 8 lined up while soldering. The second step is to remove all 8 of the 27 ohm resistors, and replace them with 10K 1/4W resistors.

The second method uses modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06).

Once MOSFETs are substituted for the TIPs in the lamp driver circuit, it is possible to replace the 27 ohm resistors with simple jumpers or even leave the 27 ohm resistors in place if they are in good shape as the low resistance will have a negligible effect on the operation of the MOSFET. However, the problem with either of these is that the MOSFETs are driven by 18 VDC Source to Gate voltage which is dangerously close to the absolute maximum rating of the IRF9530 and IRF9Z34 of 20 VDC (this also holds true for Data East MPUs). The FQP17P06 has a higher Vgs rating (25VDC) than either the IRF9530 or IRF9Z34N - but you are still driving the part at over 70% of its absolute maximum. Typical uses for these MOSFETs drive them by about 10 VDC Source to Gate voltage (or -10V for P-Channel MOSFET's used here).

By using a "Voltage Divider" circuit with two 1K, 1/4 watt resistors to divide the source 18 VDC in half, the MOSFET will be driven with 9 VDC Vgs.

[[File:WMS_Sys3-7_Lamp_FETs_Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys3-7 Lamp FETs Back.jpg|300px|right|thumb|1K resistors installed on the solder side of the board.]]
Parts Required
*8 P-Channel MOSFETs (IRF9530, IRF9Z34N or FQP17P06)
*16 1K Ohm 1/4 Watt resistors

Procedure
*Remove the TIP-42 transistors Q63, Q65, Q67, Q69, Q71, Q73, Q75, Q77
*Remove the 27 Ohm resistors R149-R156
*Remove the 2.2K ohm resistors R141-R148
*In place of the 27 Ohm resistors, install 1K Ohm resistors
*In place of the TIP 42 transistors, install the P-Channel MOSFETs, oriented the same as the TIP-42s were oriented
*On the solder side of the board, install eight 1K Ohm resistors between the MOSFET gate and the 18VDC source.
 

[[File:System3-7FETs.jpg|300px|left|thumb|Another implementation of 1K resistors installed on the component side of the board.]]
[[File:WMS_Sys3-7_1K_Resistor_Lamp_FETs_Back.jpg|300px|right|thumb|Closeup of 1 kohm resistors added to solder side of board]] 
Pay close attention when adding the 1 Kohm resistors to the solder side of the driver board on heavily burnt / delaminated boards. The resistor leg and / or the end of resistor leg comes within close proximity of the same column or adjacent column traces.
 

[[File:WMS3-7DriverFETModAlternate.jpg ‎|300px|left|thumb|Another implementation of 1K resistors installed on the solder side of the board. This implementation requires less resistor leg bending and hence, a much easier install.]]
[[File:WMS3-7FETFrontSideOnlyMod.jpg ‎|300px|right|thumb|A "component side only" implementation. Image courtesy of Victor, Pinsider "DumbAss".]] 
Yet more ways to efficiently add the voltage dividing resistors.
 

==Flash Lamp Problems==

System 3-7 flash lamps (and System 9/11 also) are driven by the same kind of circuitry that drives solenoids. Flashers are generally wired two in series (like old Christmas lights). If one lamp fails, the neither lamp will light. They are wired in series so that they split the DC voltage across two lamps, preventing them from burning out quickly.

To make the flashlamps "agile" (i.e. turn on rapidly) and to extend the life of the flashlamps, a "warming" circuit was employed which connects two series flashlamps to coil power via a 330 ohm 1 watt resistor. This causes the lamp filament to turn on very slightly, and to "warm up", ready for the power to find ground via a 1 ohm (5 ohm in System 11) resistor.

Over the years, these games have undergone "maintenance" to replace parts on the resistor board and have sometimes also been rewired, attaching the wires to different solder lugs on the flashlamp warming board.

Note: If LED flash lamps are installed instead of incandescent lamps, the 330 ohm warming resistor must be removed from the circuit. If it's not removed the lamp will remain on, albeit not at full intensity.

<center>
<gallery widths=300px heights=300px perrow=2 caption="Williams System 3-7 (and 11) Warming Board Implementation">
File:FPWarming.jpg|<center>Firepower warming board. The 330ohm resistor has clearly failed. This board is connected to the game wiring differently than Gorgar and is not factory, yet it works. The red wires are power. It's difficult to see in this pic but a yellow wire is also connected to the red wires. That yellow wire connects to two flashlamps in series. The other yellow wire returns from those flashlamps and is connected to the 1ohm and 330ohm resistors. Power finds ground through the 330ohm resistor and the black wire. This forms the "warming circuit". Power also finds ground through the 1ohm resistor, the brown/violet wire and the driver board drive transistor.</center>
File:FirePowerWarmingBoard.jpg|<center>Firepower warming board. The 330ohm resistor has been replaced. This board is also connected to the game wiring differently than Gorgar and is not factory, yet it works. The two yellow wires connect to two flashlamps in series. Red is flashlamp power. Black is ground. The remaining wire is a path to ground via the drive transistor.</center>
File:GorgarWarmingBoard.jpg|<center>Gorgar warming board. The two yellow wires connect to two flashlamps in series. Red is flashlamp power. Black is ground. The remaining brown/violet wire is a path to ground via the drive transistor. This warming board wiring matches the schematics and corresponds to factory wiring.</center>
File:System11WarmingBoard.jpg|<center>System 11 (High Speed) warming board. Note that flashlamp power is no longer routed through this board. The orange wire connects to two flash lamps in series which are then connected directly to flashlamp power. The two black wires are ground. The gray-blue wire is the path to ground via a drive transistor.</center>
</gallery>
</center>
 

[[File:WarmingResistorSchematic.jpg|300px|thumb|left|Warming Resistor circuit shown in Stellar Wars schematics. Note the two #89 lamps wired in series. They are dimly lit with power from the red wire, through the 1 ohm resistor, through the lamps, through the 330 ohm resistor, and then to ground. They will fully light when the drive transistor that services the GRY-BLK wire is switched on, providing a low resistance path to ground and effectively removing the 330 ohm resistor from the circuit.]] 
The diagram at left shows the physical connections to be made by the warming board. The schematic snippet at right is from Stellar Wars (System 4) and accurately depicts connections. The schematic contained in Gorgar is not correct for this circuit. Warming boards are not shown in any of the System 11 documentation.
 

==Switch Problems==
WARNINGS: 
*Never use a file, sandpaper, or anything more abrasive than an old business card to clean gold flashed switches. Doing so will remove the gold flashing and permanently ruin the switch.
*Never adjust switches with the game powered on. It is far too easy to short the switch, or your adjustment tool, to adjacent power (lamps or solenoids) and damage the switch matrix circuitry on the driver board.

The only switches that can be filed are tungsten switches which are both materially and physically quite different from gold flashed switches. In a System 3-7 game, the only tungsten switches are the cabinet flipper buttons and the flipper mechanism end-of-stroke switches.

Tungsten cabinet flipper switches and end-of-stroke switches "arc" and will become blackened (or whitened) and pitted over time. Once this happens, the resistance between the switch pair increases, which reduces electric current, which reduces coil power, which reduces flipper strength.

Switches vary from game to game, most are standard for WMS System 3-7.

A few of the common switches are listed here:
{| class="wikitable"
!colspan="2" |System 3-7 Switches
|-
!Part Number
!Common use
|-
|SW-1A-118 || Spinner Blade switch
|-
| SW-1A-124 || Rollover Lanes (inlanes/outlanes as well)
|-
| SW-1A-130-1 || Switch Rightmost on Ball Runway (Ball Locks, with round white nylon piece on leaf end)
|-
| SW-1A-136 || 2nd Ball Runway Switch (typical, depending on game)
|-
| SW-1A-137 || 3rd Ball Runway Switch (typical, depending on game)
|-
| SW-1A-138 || Shooter Lane Switch
|-
| SW-1A-139 || Lane Change Switch (can use SW-1A-150, usually stacked to right flipper or right EOS)
|}

These were used throughout the Williams games:
Examples are for the above include System 3, System 4 (Flash), System 6(a) (Firepower and Alien Poker), System 7 (Black Knight). Some appear on F-14 Tomcat (’87) and further, even after most Ball Ramp switches had changed over to micro switches. Black knight also used micro switch kits, which Williams provided as a field replacement kit for operators. Drop Targets also had factory micro-switch adapters fitted later to make them more reliable.

'''''Switch Assembly Note''''': The Williams factory (or more accurately their suppliers) assembled many switches so one of the blades was facing the wrong way. It should have two gold contacts facing each other, where in fact one blade faces so that the rough-sided rivet is making contact. If you have an intermittent switch, it can be worth the time to de-solder it and remove from the game and then carefully pry the switch stack apart and reassemble the switch so the gold contacts face toward each other. Keep the exact order of spacers and just reverse the one blade. While there, carefully clean the switch contacts with naptha and a clean cloth. Again, please don't use emery (or files) on these switch points! Once the gold has worn, they form "dead spots" and won't work reliably. Another symptom of the misassembled switch stacks is multiple switch closures.

===How the Switch Matrix Works===

First of all, a switch is usually an electro-mechanical device with moving parts. This includes leaf blade switches, tilt switches (where the ring is fixed and the plumb bob is the moving part of the switch) and micro-switches. When a mechanical switch closes the contacts tend to oscillate before coming to rest. It literally 'bounces' several times before remaining closed.

The CPU could see the rapid open/close events as multiple switch closures, so there is usually some 'debounce logic' built into switch matrix reading programs. The CPU sees a switch closure and then 'checks back' to see if it remained closed as few milliseconds later. If it is closed, the CPU processes the event once, scoring the correct value or in some cases triggering a solenoid to fire. In the case of Williams 3-7 games, the switch debouncing for normal switches is done at the software level; unlike other contemporary manufacturers' method, Williams' software is more sophisticated in that the definition of switches include the ability to treat a switch as fast-response (example: spinner switch), normal response (lane rollovers - longer 'ignore time' to prevent duplicate reads on a slow traveling ball), and the longest time (trough switches - where the ball would travel over the first 2 switches on a multiball machine, you would not want those to react unless a ball were truly in the trough).

As an aside, an optical switch (or opto) has no moving parts and so doesn't suffer from mechanical switch 'bounce'. (An optical switch can suffer from electronic switch bounce - many rapid activations per second - which is why they usually utilize circuitry known as a Schmitt Trigger to lower the probability of debounce errors). It also shouldn't need adjustment or in theory wear out as quickly as say a micro-switch. However, an opto needs additional circuits and is not as simple to work on or replace as other switch types. Although you can not see an infrared transmitter with you naked eye, you can look at it with a digital camera. Optos were never used in System 3-7 games, although they were engineered and prototyped just at the end of System 7.

Wiring up every switch separately with multiple wires running to the backbox would be expensive in the amount of wiring and in the number of inputs required to the game's logic. Rather than do that, the engineers designed a switch matrix with 8 column wires and 8 row wires, creating a 'matrix' of 8x8 giving a total of 64 possible switches. Not all of these switch positions are used.

The first column of the switch matrix (COL 1) is dedicated to the same switches on the System 3-7 games. You can check in a manual, but these will be the cabinet tilts, the coin switches which sense coin drops, the credit button (to start a game) and the high score reset which is also in the cabinet (on the coin door). In order from row 1 through row 8, they are the plumb bob tilt, ball roll tilt, credit button, right coin chute, center coin chute, left coin chute, slam tilt, and high score reset button.

For the most part other switches will be on the playfield (exceptions could be a lane change or magnasave button/switch).

So how is the switch matrix read by the MPU? It uses the most useful Peripheral I/O device in this pinball era, the Motorola 6821 PIA (earlier this was the MC6820 PIA).

The 6821 is made up of two 8 bit ports, one port is known as 'Port A' and the other 'Port B'. Any of the 16 pins can be configured as inputs or outputs. That's exactly what's needed to drive our Switch Matrix! An 8-way output port B to 'send' (or strobe) down the Columns to the switches, and an 8-way input port A to 'read' the Rows from the switches. The Columns are known commonly as 'Drives' or 'Strobes' and the Rows are known as 'Returns' for this reason. In a similar way (an 8x8 matrix) another PIA is used for the Lamp Matrix.

The switch matrix PIA is at IC11 on the Driver Board (also called PIA II). This PIA doesn't drive the switch matrix directly from it's TTL output pins. There are +5v powered 'pull-up' resistors and 4 IC's which act as drivers/buffers helping to protect the PIA from damage if the switch matrix is shorted.

;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.
:A 7406 or 74LS06 will work and are common parts.
;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.
:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 14-leg DIP will work.
:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''

The CPU writes to the output port of the PIA driving column 1, then the return input port is saved, holding the status of all 8 rows in one byte. The program then 'looks' at each of the rows 1-8 in quick succession. It checks to see if the signal is getting through on the row that's currently being read. Think of it as an 8 bit answer for that column showing which switches in that column are closed. Say 00010001 returned would mean switches at C1,R4 and C1,R8 are closed.

So for every 'drive' down a column, the machine does 8 'reads' of the rows. Then the CPU moves on and drives column 2, looking again at each of the rows 1-8. It continues through all of the remaining columns in this way. This is done very rapidly by the CPU, strobing the whole matrix looping over and over many times a second. Because it's so fast, even multiple switch closures are rarely missed, in fact as mentioned above it has to debounce the results to obtain an accurate result. Williams' operating system software on machines from at least system 6 up through system 11 have differing debounce values depending on the type of switch, allowing greater sensitivity on certain types of switches, and desensitizing others (such as lock or trough switches).

The diodes on every switch help to steer the drives only to the row that's being read and not back into other parts of the matrix. That's why good diodes on switches are so important, as they must only allow current to flow in one direction: '''''from''''' column '''''to''''' row. Essentially that's how the switch matrix reads switch closures.

This [https://www.flippers.be/basics/101_switch_matrix.html article] by Aeneas describing a later game's switch matrix may be useful as a different explanation with a diagram. Transistors can be used on the drives (as with modern games like DE or Stern ), different buffer chips can be used, but the basic switch matrix design hasn't changed over the years.

Finally a warning about protecting the switch matrix.
Please note that '''''nothing''''' will protect the switch matrix IC's and PIA if (for example) the +50v solenoid voltage is shorted into the matrix. This happens if the 'lane change' switch is attached in a stack on the flipper mech and shorted to the EOS switch. In later designs the 'lane change' was moved to be stacked with the flipper buttons (nearly as bad) or to a separate button which was a better design. Be very careful if working under the playfield '''not to short the solenoid or lamp power into a switch'''. It can be a lot of work to repair the damage done to the driver board, so be careful with you screwdriver and loose solenoid power wiring. Most people who have been repairing games long enough learned the hard way, and won't work under the playfield with the power on.

===Special Switches===
There are a few switches that are dedicated, and not part of the switch matrix. The coin door Advance and Auto/Up Manual/Down switches, which let you start diagnostic tests when the switch matrix is faulty. 

Also, there are a maximum of 6 special solenoid switches, which directly connect to the solenoid logic on the driver board. When Williams first designed these games, they were worried that the CPU couldn't always 'keep up' with the ball hits to the pop bumpers or slingshots. So during game play the switches on the playfield fire the special solenoids directly from the playfield. These usually include the spoon switches on the pop bumpers and slingshot stand-up switches.

There is a 22uF capacitor and a 100 ohm resistor mounted across the special solenoid switches. The use of the capacitor and resistor creates what is called an [http://en.wikipedia.org/wiki/RC_circuit RC circuit]. The RC circuit is used to filter noise from the switch signal as well as to ensure a minimum pulse length for the solenoid activation. If using a polarized capacitor the positive terminal goes to the tie point with one end of the resistor attached. Should a special solenoid lock on, and the switch leaves are properly gapped, the issue may be a shorted switch capacitor or resistor.

All pop bumpers and slingshots have a secondary switch which is part of the switch matrix. It closes when the coil is fired and tells the CPU to increment scoring and in some cases to trigger sounds for these devices. The scoring switch is mechanically closed, by the 'elbow' of the slingshot arm or by the bakelite yoke connected to the pop bumper ring.

Confusingly, the CPU can also fire the 6 special switches from PIA lines for the diagnostic tests, but these PIA signals are never used during game play. If all these solenoids work during diagnostic tests, but not in game play it points to the switch inputs or the 7408s at IC6/7. It won't be the 7402s at IC8/9.

I have seen a game that worked in play perfectly, but the diagnostics could not fire two of the pop bumper solenoids during tests. This was a Switch Matrix PIA with faulty output at pins 19 (CB2) and 39 (CA2), other than that the PIA was working correctly and so it could still be used to drive the Switch Matrix. If a switch row or column went out, the PIA would then have to be replaced.

: '''Here is a list of the PIAs and where the pins are that fire the 'special solenoids' during diagnostics:'''
{| class="wikitable"
!colspan="5" |Special Solenoid Diag. PIAs
|-
!ST#
!PIA
!CHIP
!Pin #
!Location / Board
|-
|1 ||III ||IC10 Lamps ||19 ||Middle PIA on Driver Board
|-
|2 ||III ||IC10 Lamps ||39 ||Middle PIA on Driver Board
|-
|3 ||II ||IC11 SW Matrix ||19 ||Left PIA on Driver Board
|-
|4 ||II ||IC11 SW Matrix ||39 ||Left PIA on Driver Board
|-
|5 ||IV ||IC 5 Solenoids ||39 ||Right PIA on Driver Board
|-
|6 ||I ||IC18 Displays ||19 ||Via 1J1-26 on CPU Board
|}

===Testing the Switch Matrix===
To test the switch matrix in the game, first remove both Switch Matrix connectors on the top right of the driver board. J2 is Column (green wires) and J3 is Row (white wires). Then run a switch test from diagnostics, you should get no switches being sensed.

Use an alligator test lead as follows:
* Connect one end of the test lead's alligator clip to the column pin, starting at column 1. That's the bottom pin of J2.
* Then use the other end of the test lead to touch the appropriate row pins.
* Start at the bottom pin of J3, which is row 1. You should see switch #1 indicated (R1C1).
* Move the probe to the next pin up on J3, which is row #2. You should see switch #2 indicated (R2C1).
* When you got to the top of the row pins, move the clip end to COL #2 (up one pin) and start again with row #1.
* Activate each switch in turn by connecting the appropriate 2 male pins on the CPU board with your test lead.

Using your switch matrix chart from the manual as a guide, you may find the faults as your game "sees" on the same switches.

If you get an error in sequence, more than one switch registers at a time or you are missing a row or column - then you '''know the problem must be on the MPU board'''. You can either try to fix it or send the board out for repair.

If the above test works correctly, meaning all switches register correctly then your problem must be the wiring or on the playfield.

===Testing the Switch Matrix PIA===
No section on the switch matrix is complete without mentioning the switch PIA. That IC and 4 buffer IC's are the only logic in the switch matrix. The complete instructions for testing all the PIAs are beyond the scope of this section.

The only sure-fire way to test the PIA is with the 'Leon Borre test ROM' in the MPU board. You do this by taking the MPU and Driver boards out of the game and putting them on the bench. This will also let you trace back through the circuit to find a fault more easily, and it's not as hard as you may think. It will also exercise the CPU memory and test all the PIAs on the Driver Board, not just the switch matrix PIA. Here are his excellent instructions:

[[Leon_Borre_Repairing_Williams_System_3-6_CPU_Boards | Leon's Repair Pages for WMS System 3-6 games]] including a free test ROM.

[[Leon_Borre_WMS_System_7_Repair | Leon's Repair Pages for WMS System 7 games]] including a free test ROM.

These Belgium guys are knowledgeable about pinball.

Should any of the chips in the switch matrix prove to be faulty, be particularly cautious in replacing them. They have a greater than usual tendency for lifted traces and pads when desoldering. Heat rising from the lamp matrix resistors has a tendency to not only cause these chips to fail, but also to loosen the bond between the circuit board and the solder pads and traces on this area of the driver board.

===Switch Matrix Components===
Final thoughts about components which make up the switch matrix.

The passive components:
On the driver board there is an RC network, made up of 16 x 4.7K pull-up resistors that you can measure with a DMM. Tolerance is not critical, but should measure between 4.5K to 5K which is about a +/- 5% range.
There are also 16 x capacitors (470pF at 50v, ceramic) these should not measure as a short, if in doubt just replace them.
And 8 x 1K ohm resistors at the switch inputs (rows) at R196-R203 these can not be open or shorted and must be around 1K each.

You can see the above chips inverting signals with the game running and a logic probe. Check if signals look weak or suspect. If you see a signal on the input side and then nothing inverted on the output side, then that's your problem.

{| class="wikitable"
!colspan="4" |Beyond that IC15-18, which are the Switch Matrix inverting buffer / drivers:
|-
!IC Location
!Inverting Pairs. Leg a to b listed as a,b
!Switch Row/Col Numbers
!IC Part Number /Eqivalent
|-
|IC15 ||3,2 7,6 14,15 9,10 in that order ||Rows 1-4 ||(MC)14049U / 4049U
|-
|IC16 ||3,2 7,6 14,15 9,10 in that order ||Rows 5-8 ||(MC)14049U / 4049U
|-
|IC17 ||2,1 6,5 12,13 8,9 in that order ||Columns 1-4 ||7406(S) / 74LS06
|-
|IC18 ||2,1 6,5 12,13 8,9 in that order ||Columns 5-8 ||7406(S) / 74LS06
|}

{| class="wikitable"
!colspan="5" |J2 (Column) and J3 (Row) connector pins:
:
|-
!Connector
!Male connector Pins
!Switch Row/Col Numbers
!IC Location
!IC Part Number /Eqivalent
|-
|2J2 ||pins 1-3 and pin 5 ||Columns 5-8 ||IC18 ||7406(S) / 74LS06
|-
|2J2 ||pins 9-6 ||Columns 1-4 ||IC17 ||(MC)14049U / 4049U
|-
|2J3 ||pin 1 and pins 3-5 ||Rows 5-8 ||IC16 ||(MC)14049U / 4049U
|-
|2J3 ||pins 9-6 ||Rows 1-4 ||IC15 ||(MC)14049U / 4049U

|}

Except for the 6821 PIA which is getting harder to find, all the switch matrix components are readily available.
However there are acceptable substitutes on the market. Any of the following part numbers are drop-in replacements for the 6821.
68A21, 68B21, 6521, W65C21N.

===Wire Jumpers on System 7 Driver Boards===
[[File:ZeroOhmJumpersS3-7.jpg ‎|300px|left|thumb|A Williams System 3-7 Driver Board, retrofitted with wire jumpers at R04-R211]]
Williams removed some resistors from the switch matrix inputs and used wire jumpers instead. This happened from the start of System 7. The first thing to do with a driver board (which may not be from that game) is to measure these resistors and make sure you have the the driver board set up for the correct game. '''''While a board with wire jumpers can be used in System 4-6 games, using a board with resistors in a System 7 game will cause problems.''''' Replacing the 330 ohm resistors with wire jumpers helps with switch sensitivity and with sensing more than one switch closure at the same time.

On driver boards from Black Knight and later System 7 games, there should be 8 wire jumpers (or zero ohm resistors) used on the switch matrix at positions W9-W16. These are located on the upper right hand corner of the Driver Board just to the left of J2, the top right connector which is the switch matrix column drive. To the left are two columns of 7 resistors each, the second column should be the wire jumpers, along with the top position of the next column to the left (column with 2 resistors only).

System 4-6 Driver boards, (games like Alien Poker, Firepower and earlier SS games) were released with 330 ohm resistors (orange, orange, brown) in these 8 locations. Starting with Black Knight and later (System 7 games) they are called R204-R211, and are zero ohm resistors (usually a tan body with one black stripe). You can replace or jumper over them with wire leaving the resistors in place. In all other aspects the driver boards are identical, so it's easy to convert between the two. This is why they are usually known as ''System 3-7 driver boards''.

Before you start to replace parts on the driver board, be sure your playfield switches are working and the diodes are good. You need to unsolder one end of the diode from the switch to be able to test it correctly with a DMM on the diode setting. While you are there, clean the switch with a business card soaked in naptha or contact cleaner sprayed on the business card (with the game off, contact cleaner is flammable!) See if any blackness comes off on the card. You can also gently wipe the contacts until shiny with a Q-tip or the corner of a clean rag dipped in isopropyl alcohol. A pencil eraser also works well to clean switch contacts.

=Game Specific Problems and Fixes=
==Black Knight==
===Magna Save Performance===
There are 2 under playfield relays used to shunt high voltage to the magna saves. These are high voltage contacts and should be filed for maximum conductivity and power for the magnets.

===Magna Save Magnets Not Working===
If the magnets are not working in test or game, make certain that the white-red wire is tied to the ground screw in the backbox. This white-red wire is fed from the relay coils, which enables each appropriate magnets.
===Fast moving ball flies through upper lock===
Mount a shooter lane bracket underneath the plastic of the upper ball lock trough. With creative bending, all ball motion will stop on entering the trough. The ball will drop down ensuring credit is awarded for the lock.

===Ball Lock Scoring Bug===
There is a software bug in version L-3 and L-4 where instead of getting 5000 points with other balls in the lock you get 10,000, scored in increments of 5000. There is no current fix for this; it may have been intentional for the additional score (usually picked up by another player) but probably an oversight by the original programmer. There is a footnote in the operator's manual referencing this. It is unknown what the original intention was.

===Right Ramp Gate Adjustment===
It is erroneous to have the mystery rollunder gate score in one direction only; the switch should activate both going UP to the upper playfield as well as DOWN to the lower playfield. It can be a strategy in multiball to let it roll down the switch, multiplying the mystery value.

==Firepower==
===Firepower Won't Start a Game===
Firepower and other multi-ball games are infamous for being stubborn if there aren't three balls in the trough, or if one of the trough switches isn't closed. Additionally, multiball games usually have a shooter lane switch. If MORE than 3 switches are closed, the game will also not start.

My Firepower, in particular, is frequently upset if the right-most switch isn't closed, and that switch has an unusual actuator on it that doesn't work as well as a common rollover actuator. That switch is a little mangled, so it's the one that is most problematic. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 18:12, 21 May 2014 (CDT)

==Time Warp==
===Time Warp loses background sound occasionally===
There is a software bug in Time Warp where the background sound (if enabled) will go mute at ball launch. This happens whenever the ball kicker launches twice, or when a ball drains without scoring any points. There is a fix for this identified as Time Warp L-3 however it is not officially sanctioned by Williams and so is not readily available.

=Parts Substitutions & Replacements=
==Boards==
* Displays
** [http://xpinpinball.com/product-category/xpin-displays/ XPin]
** [http://www.rottendog.us/?product=dis326 Rottendog 6-Digit]
** [http://www.rottendog.us/?product=dis079 Rottendog 7-Digit]
* MPU
** [http://www.rottendog.us/?product=mpu327 Rottendog] (no longer supports System 7 games)
* Power Supply
** [http://www.rottendog.us/?product=wdp3211a Rottendog]
** [http://xpinpinball.com/product/xp-wms8345/ XPin]

NOTE: [http://pinballpcb.com/ Kohout Enterprises] has begun manufacturing circuit boards again.

=Repair Logs=
Did you do a repair? Log it here as a possible solution for others.

==Unreliable +5V==
A Firepower won't boot consistently. It was reliable before it was moved in a box truck. +5V supply measures low. For some reason, I decided the problem had to be the diodes in the power supply and replaced them, which didn't help. I replaced the +5V cap in the power supply, C16, and all was well. (Thirty year old filter caps are all absolutely suspect.)

Once I had the cap loose, I discovered I could shake it and hear it rattling inside. Presumably, the jelly roll of electrolytic was dried out. Shaking it might have the internal components in the right place, but probably not. A few miles in the back of the truck was enough to wreck it, more permanently before. The game has been very well-behaved since replacing the cap with a new one. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 18:12, 21 May 2014 (CDT)

==Unreliable +5V, part 2==
All classic pinball boards rely on 5V logic. Most data sheets indicate 5V, +/- 0.25V. Always check the 5V on the power supply, AND on the MPU board. Note that there may be 5.2V on the power supply, but 4.8V on the MPU. This is too low.. small pulses can pull the 4.8 below 4.75 fairly easily and cause resets. If there is less than 5V on the MPU board, but the voltage is right on the supply, try checking voltage drops at each individual connector pin. One will usually find that pins will have built up tarnish, or heat has turned them grey or brown.. this is the tip off that the connector needs to be replaced. I know, groan.. it can be a pain, but replace the header in the circuit board. Make sure to remove or clip the key pin. Then replace the connector on the wires (female) with crimp and poke type. Use a ratchet crimper, and tug on them after each crimp to prove that they are good. Replace the wires one by one.. clip, crimp, poke.. copy each wire position from the original one one at a time, and keep in mind that the connectors have a ramp and go on one way. Replace and power up, and then go back to the meter, and verify that the voltage on the MPU board has risen..

==CPU will not start==
This happens to involve a Type 2 sound board, but it could apply to an MPU board or a Type 1 sound board. The reset pin voltage (CPU Pin 40) was low and would slowly climb after power on, but not enough to allow the CPU to start. All components in the reset section were good, and replacement parts did not make any difference. The problem was the sound board's PIA. Its reset line was pulling down the voltage so much that the CPU would not start. After replacing the PIA, the sound board booted and worked fine.

Williams System 3 - 7

2023-03-21T18:56:25Z

Jimpal: Reverted edits by ForceFlow (talk) to last revision by Chibler

Click to go back to the [[Williams_Repair_Guides | Williams solid state repair guides index]].

=Introduction=
Williams entered the [http://www.pinwiki.com/index.php?title=Glossary#Solid_State_.28SS.29 SS] or Solid State era with a conversion of a 1976 Williams [http://www.pinwiki.com/index.php?title=Glossary#Electro_Mechanical_.28EM.29 EM] or Electro Mechanical pinball game called [http://www.ipdb.org/machine.cgi?id=4828 Grand Prix].

'''System 1''' is considered to be the Solid State version of ''Grand Prix''. It is thought that about 5 Grand Prix EM games were converted to SS prototypes using the new System 1 MPU Board and digital displays. The computer was only used for accumulating and displaying the player scores.

IPDB links: [http://www.ipdb.org/machine.cgi?id=5647 Grand Prix SS version]          [http://www.ipdb.org/machine.cgi?id=1072 Grand Prix EM version ]

'''System 2''' was next, with a 10 unit run of another 1976 EM game called ''Aztec''. A working SS version is very rare. Both System 1 & 2 occurred quickly after each other at the end of 1976. Aztec SS was still a hybrid machine retaining the EM chime unit in the cabinet and a credit window with an EM numbered reel behind the backglass). Player scoring was still the only digital function at that time.

IPDB links: [http://www.ipdb.org/machine.cgi?id=4828 Aztec SS version]          [http://www.ipdb.org/machine.cgi?id=119 Aztec EM version ]

'''System 3''' games were the first Williams SS production games, starting with ''[[Hot Tip]]'' in Nov. '77 and ending with ''[[Disco Fever]]'' in Aug '78. There were based on the Motorola 6800 8-bit CPU and using a Motorola 6820 PIA (Peripheral Interface Adapter) to handle the Display I/O from the MPU board. They also had three other 6820 PIAs on the Driver Board reading targets and other switches as inputs and controlling the insert Lamps and solenoids as outputs. Solenoid drives were mainly used for ball handling by firing coils, with a few triggering sound calls or a 'start of game' tune. This was the start of Williams using computers for game rules and settings. At this point they designed an 8x8 Switch Matrix, an 8x8 Lamp Matrix and solenoids driven by Darlington transistors. This design remained virtually unchanged to the end of Williams System 7.

During System 3 (''[[Phoenix]]'' and ''[[Disco Fever]]'') a memory protect circuit modification was added as to help protect CMOS RAM data during power up and power down of the game. DIP switches were used to program game settings (such as # of balls per game, high score replays).

'''System 4''' games ran from ''[[Pokerino]]'' in Nov '78 through to ''[[Stellar Wars]]'' in Mar '79, according to IPDB.com. A notable game which outsold all of the other System 4 games combined with a production run of 19,505 was ''[[Flash]]'' (Steve Ritchie's first designed game for Williams). During System 4, Williams moved from using DIP switches to change game settings to having the game settings changed from the coin door switches. The settings were still stored in battery protected CMOS RAM. [ed Note: Citation needed] A coin door interlock switch enforced that CMOS memory could not be modified unless the coin door had been opened by the operator. Some of the game audits (coins accepted, total number of games played, etc.) still could not be changed without access to the MPU board behind the backglass.

'''System 6''' games ran from ''[[Tri Zone]]'' in Jul '79 to ''[[Scorpion]]'' in Jul '80. Two notable games from this era were from the end of '79 and the beginning of '80 ''[[Gorgar]]'' and ''[[Firepower]]''. Gorgar (14,000 produced) was the first talking pinball, and Firepower (17,410 produced) both talked and introduced the 'Lane Change' and 'Multiball (tm)' features to SS games. Note that there had been Multiball play available in EM games, it just wasn't called Multiball (tm) until Firepower. and this is a common misunderstanding. The features these games introduced became standards for almost all pinball games produced right up until today.

'''System 6a''' deserves to be mentioned here as it marked a transition to System 7. The game ''[[Alien Poker]]'' from Oct '80 used the Syatem 6a MPU board (which was not very different from System 6). But it supported 7 digit scoring displays and a redesigned Master Display Driver board, located behind the backglass on the back of the 'Lamp Board'. It also used a special 4 digit "credit/match" display in the approximate position where the System 6 Master Display Driver had been showing the same information (on a 6 digit display, with 2 of the digits unused). This new 7 digit scoring displays with a 4 digit credit/match display were then used in all the System 7 games (and System 9).

'''System 7''' games ran from ''[[Black Knight]]'' in Nov '80 through to ''[[Star Light]]'' in Jun '84.

IPDB link: [http://www.ipdb.org/search.pl?mpu=4&qh=checked&ng=checked&sortby=date&searchtype=advanced Complete System 7 Game list]

''Black Knight'' (13,075 produced) introduced a two level playing field and Magna-Save (tm) where the ball could be stopped from draining down the sides by pressing a cabinet button that activated an electromagnet. ''Star Light'' (100 produced) was a 'boutique' game by Williams' production standards as the focus was on ramping up production for the first System 9 game Space Shuttle (7,000 units). At least one Star Light game was made as the Prototype for System 9.

Note: Further discussion of changes and good pictures of the backbox boards for System 3-7 games can be found here:
[http://tuukan.fliput.net/wms_en.html Tukkan.fliput.net]

=Games=
==System 3==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Hot Tip]]|| 11-1977 || 477 || Chimes || ||
|-
|[[Lucky Seven]]|| 03-1978 || 480 || Chimes || ||
|-
|[[World Cup]]|| 05-1978 || 481 || Type 1 Sound || ||
|-
|[[Contact]]|| 05-1978 || 482 || Type 1 Sound || ||Widebody
|-
|[[Disco Fever]]|| 08-1978 || 483 || Type 1 Sound || ||Used banana flippers
|}

==System 4==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Pokerino]]|| 10-1978 || 488 || Type 1 Sound || ||Widebody
|-
|[[Phoenix]]|| 11-1978 || 485 || Type 1 Sound || ||
|-
|[[Flash]]|| 01-1979 || 486 || Type 1 Sound || ||First game with continuous Background sound/Later games produced on System 6 platform
|-
|[[Stellar Wars]]|| 03-1979 || 490 || Type 1 Sound || ||Widebody/Later games produced on System 6 platform
|}

==System 6==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Tri Zone]]|| 07-1979 || 487 || Type 1 Sound || ||
|-
|[[Time Warp]]|| 09-1979 || 489 || Type 1 Sound || || Used banana flippers for most of run.
|-
|[[Gorgar]]|| 12-1979 || 496 || Type 2 Sound w/ Speech || ||First game with speech
|-
|[[Laser Ball]]|| 12-1979 || 493 || Type 1 Sound || || Widebody
|-
|[[Firepower]]|| 02-1980 || 497 || Type 2 Sound w/ Speech || ||First SS Multiball (3 balls). First lane change.
|-
|[[Blackout]]|| 06-1980 || 495 || Type 2 Sound w/ Speech || || First Williams game where a relay was used to turn general illumination on / off for effect.
|-
|[[Scorpion]]|| 07-1980 || 494 || Type 1 Sound || ||Widebody
|}

==System 6A==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Algar]]|| 09-1980 || 499 || Type 1 Sound || 7 digit display board||Widebody
|-
|[[Alien Poker]]|| 10-1980 || 501 || Type 2 Sound w/ Speech || 7 digit display board||
|}

==System 7==

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Notes
|-
|[[Black Knight]]|| 11-1980 || 500 || Type 2 Sound w/ Speech || ||First game with magnasave
|-
|[[Jungle Lord]]|| 02-1981 || 503 || Type 2 Sound w/ Speech || ||
|-
|[[Pharaoh]]|| 05-1981 || 504 || Type 2 Sound w/ Speech || ||
|-
|[[Solar Fire]]|| 07-1981 || 507 || Type 2 Sound || ||
|-
|[[Barracora]]|| 09-1981 || 510 || Type 2 Sound || ||
|-
|[[Hyperball]]|| 12-1981 || 509 || Type 2 Sound ||Uses different driver board than pinball games ||Not a pinball - a flipperless game firing tiny pinballs
|-
|[[Cosmic Gunfight]]|| 06-1982 || 502 || Type 2 Sound || ||
|-
|[[Varkon]]|| 09-1982 || 512 || Type 2 Sound || || Pinball in stand-up Video cabinet
|-
|[[Warlok]]|| 10-1982 || 516 || Type 2 Sound || ||
|-
|[[Defender]]|| 12-1982 || 517 || Type 2 Sound || ||
|-
|[[Time Fantasy]]|| 03-1983 || 515 || Type 2 Sound || ||
|-
|[[Joust]]|| 04-1983 || 519 || Type 2 Sound || ||Two player head-to-head pinball
|-
|[[Firepower II]]|| 08-1983 || 521 || Type 2 Sound || Uses 50v Flipper Power Supply Board ||
|-
|[[Laser Cue]]|| 02-1984 || 520 || Type 2 Sound || ||
|-
|[[Star Light]]|| 06-1984 || 530 || Type 2 Sound || ||
|}

Game date of release and model numbers provided by the Internet Pinball Database - http://www.ipdb.org

=Documentation=
==Manuals & Schematics==
Most manuals and ROM files can be found on IPDB.org for each specific game.

* [[media:01-backbox-sys6.pdf|System 6 Backbox Wiring Diagram]]

==Parts Catalogs==
Parts catalogs can also be useful, which include part numbers (helpful for purchasing parts online), exploded views of assemblies (helpful to see how the assemblies are put together), and board layouts & parts lists, and diagrams for controlled lamp, solenoid, and rubber locations.

Online copies of Bally & Williams parts catalogs can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball].

{| class="wikitable"
|-
!Manufacturer
!Catalog
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|1980 Parts Catalog
|
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/ltjq/#p=1 Viewer]
|Hot Tip, Lucky Seven, World Cup, Contact, Disco Fever, Phoenix, Flash, Tri-Zone, Pokerino, Time Warp, Stellar Wars, Laser Ball, Scorpion, Blackout, Gorgar, Firepower, Algar, Black Knight, Alien Poker, Cosmic Gunfight, Jungle Lord, Pharoah, Solar Fire, Hyperball, Barracora
|This catalog covers all system 3-6 games, and the first third of the system 7 games.

|}

==Service Bulletins==
Most service bulletins can be found on IPDB.org for each specific game.

==Instruction Cards==
* [http://www.pinballrebel.com/pinball/cards/ Instruction Cards & Labels]

==Fuses==
===Power Supply===

{| class="wikitable" style="text-align: center;"
|+Williams System 3 - 7 Power Supply Fuse Ratings
|-
!System
!F1
!F2
!F3
!F4*
!F5
!F6
!F7
|-
|3 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 15amp FB || 4amp SB || NA || NA
|-
|4 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 4amp FB || NA || NA
|-
|6 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 4amp FB || NA || NA
|-
|7 || 1/4amp SB || 2 1/2amp SB || 8amp FB || 10amp FB || 7amp SB || 7amp SB || NA
|}

Note: The value of F4 does vary. Check the game manual for the correct rating. It's usually 10A for games with 2 flippers. Later System 7 games with a separate flipper power supply do not use F4. 

==ROM Files==
Most manuals and ROM files can be found on IPDB.org for each specific game.

* [http://www.planetarypinball.com/mm5/Williams/tech/roms.html ROM Files]

Note: The ROMs hosted on Planetary Pinball for World Cup has an issue. World Cup requires a [[#White_Flipper_ROM_Exceptions|special white flipper ROM specific to World Cup]], which [http://www.ipdb.org/machine.cgi?id=2810 can be found on IPDB].

===Combining System 3-6 Original ROMs Into a Single ROM at IC14===
[[File:WMSSystem6ROMConfig.jpg | thumb | left| 300px| A System 6 TriZone MPU, featuring combined ROM images at U14.]] 
For all System 3-6 games, the ROMs that might be located at U26, U22, and U21 (left to right on the top ROM row) can be replaced with a single 2716 2kb ROM (or EPROM) at IC14 that contains the combined images. When doing so, jumper J3 should be IN, jumper J4 OUT. These jumpers are located just above the ROMs and to the right of IC15. 

===Diagnostic ROMs by Pincoder===
Free Diagnostic ROM images for Williams System 3-7 games can be found here:
* [https://pincoder.ca/ Pincoder Website]
They require the use of EPROM chips and a chip programmer. However, you can choose to skip sourcing EPROMs and the chip programmer by using the available [https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/ Pincoder Adapter] right out of the box. Simply plug it into the MPU board, select a test, and power on the game. Full documentation can be downloaded from the Pincoder website. The ROM images and the adapter are actively supported.

===Flipper ROMs===
The OS (Operating System) for a Williams pinball game is called the Flipper ROM. Flipper ROMs with the same color label can be considered generic, although there is at least one exception where a 'custom' White Flipper ROM was used "World Cup".

The Game ROM can be considered the 'personality' ROM, it provides the rules and objectives that are specific to that game's playfield layout. It also maps the Lamps, Solenoid and Switch Matrix to their specific purpose for that game and controls how they are sequenced and timed. Examples would be the 'attract mode' lamp sequence or when sound / speech select calls are made.

Because of large game production runs, Williams bought batches of Masked ROMs (fixed and not erasable) for the games. This was cheaper at the time than using Eproms (UV erasable, with a small window) as Eproms were still fairly expensive in the 80's. They used the same method for producing most of their Flipper, Game and Sound ROMs.

It is sometimes a good idea to replace old masked ROMs with EPROMs, since the original masked ROMs are 30+ years old and as the legs blacken and tarnish, they will weaken and fall off. For a similar reason, many of the ROM sockets on the MPU boards will need to be replaced, especially any sockets bearing the words 'Scanbe', which are poor quality. Masked ROMs are very stable as they start life as all 1's and then the information is programmed by "burning" each selected bit open, like blowing a tiny fuse. This process is not reversible, and ROMs will rarely lose their programming over time, unless the remaining whisker-like "fuses" start to fail. The practice and term to "burn" ROMs carried over to other storage media, such as CDs and EPROMs, even though different technologies and processes were used to store the data.

====Flipper ROM Colors====
Williams used standard ROM files for System 3-7. These two Flipper ROMs are located at IC17 and IC20. Systems 3-6 use two 2716 or 2316 Eproms, while system 7 used a 2716 in IC20 and a 2532 in IC17 (a 2732 can be used at position IC17 after modifications are made to the board).

=====White Flipper ROMs=====
White flipper ROMs were used in all System 3 games and two System 4 games...
*Hot Tip
*Lucky 7
*World Cup
*Contact
*Disco Fever
*Pokerino (system 4)
*Phoenix (system 4)

=====White Flipper ROM Exceptions=====
World Cup uses White Flipper ROMs, but the ROM in IC17 is unique. The MPU will not boot and run with the standard White flipper ROM. However, the World Cup White flipper ROM can be used in all other White Flipper ROM games.

=====White Flipper ROM Issues=====
When downloading ROM software for World Cup, be aware the code available directly from Planetary Pinball has known faults and will not work properly. Code available from IPDB generally is correct and functional. The issues with these games is as follows:

World Cup: Provided with the standard IC17 Flipper Rom, not the unique one required for World Cup.

Lucky 7: When the original 512 byte files were combined into a 2k file for IC14 Game Rom, blank areas were entered incorrectly.
This causes the machine to register a failed checksum test when attempting to enter settings via the dip switches. (Note: The copy on Planetary Pinball appears to have been corrected).

Hot Tip: When the original 512 byte files were combined into a 2k file for IC14, they were done out of order. (Note: The copy on Planetary Pinball appears to have been corrected).

====Yellow Flipper ROMs====
The yellow flipper ROMs were used in 2 games...
*Stellar Wars
*Flash (later production of Flash used Green flipper ROMs, which are preferred. The game ROM version must match the flipper ROM color)

====Green Flipper ROMs====

The green flipper ROMs were used in System 6 and 6A games from Tri Zone (Jul '79) to Alien Poker (Oct '80)...
*Tri Zone
*Time Warp
*Gorgar
*Laser Ball
*FirePower
*Blackout
*Scorpion
*Algar
*Alien Poker

=====Green Flipper ROM Exceptions=====

Ted Estes developed a "divide by 10" ROM that allows /10 scoring for all 6 digit Green flipper ROM games with the exception of Algar and Alien Poker. These 2 games utilize an extension to the operating system ROM contained wholly in the game ROM which is incompatible with the Ted Estes hack (when enabled - with the hack disabled, the game works fine). Installing the hacked ROMs in these games isn't recommended since there may be other side effects.

The Alien Poker and Algar operating system extensions shift internal scoring before and after the normal routines. i.e. Internally, Alien Poker and Algar are 6 digit games.

====Blue Flipper ROMs====
The blue fipper ROMs were used in all System 7 games, Black Knight (Dec '80) and later...
*Black Knight
*Jungle Lord
*Pharoah
*Black Knight Limited Addition
*Solar Fire
*Barracora
*Hyperball
*Thunderball
*Cosmic Gunfight
*Varkon
*Warlock
*Defender
*Rat Race
*Time Fantasy
*Joust
*FirePower II
*Laser Cue
*Star Light

=====Blue Flipper ROM Exceptions=====
Star Light (June '84, 100 produced) which was the last System 7 game, appears to have non-standard Blue Flipper ROMs. For small production runs, games were supplied from the factory with EPROMs.

==Circuit Board Schematics and Assembly Drawings==
===Connectors===
* [[Media: Molex-Connectors-Firepower-1.1.pdf|System 3-7 Molex Connectors]]

===Displays===
* [[media:08-masterdisplayboard-sys3-6.pdf|Display Diver Board Assembly Drawing]]
* [[media:09-masterdisplaylogic-sys3-6.pdf|Display Driver Board Logic Diagram]]

===Driver Board===
[[File:System3-7DriverBoardLayout.jpg|300px|thumb|left|Williams System 3-7 driver board layout]] 
* [[media:05-driverlogic-sys3-6.pdf|System 3-7 Driver Board Logic Diagram]]
* [[media:04-driverboard-sys3-6.pdf|System 3-6 Driver Board Assembly Drawing]] (Note: The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)
* [[Media:wms-sys3-6_driver-board_layout.pdf|System 3-6 Driver Board Layout]]
* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf|System 3-6 Driver Board Schematics (1 of 2)]]
* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf|System 3-6 Driver Board Schematics (2 of 2)]]
 

===MPU===
[[File:WilliamsSystem3MPURevisionA.jpg ‎|left|thumb|300px|System 3 MPU IC Locator]] 
System 3 MPU IC Identification Map. 
The System 4 MPU adds only IC26 on the left side of the board, just above IC22 where the odd looking solder pads are.
 
* [[media:wms-sys3-mpu-layout.jpg|System 3 MPU Board Layout]]
* [[media:wms-sys3-mpu-schematic.jpg|System 3 MPU Board Schematic]]
 
* [[media:Williams_System-4_MPU_Layout.jpg|System 4 MPU Board Layout]]
* [[media:Williams_System-4_MPU_Schematic.jpg|System 4 MPU Board Schematic]]
 
* [[media:03-cpulogic-sys6.pdf|System 6 MPU Board Logic Diagram]] (Note: Because IC9 and IC10 can be bypassed directly, this diagram is accurate for System 6a)
* [[media:02-cpuboard-sys6.pdf |System 6 MPU Board Assembly Drawing]] (Note: Because IC9 and IC10 can be bypassed directly, this diagram is accurate for System 6a)
* [[Media:wms-sys6_mpu_layout.pdf|System 6 MPU Board Layout]]
* [[Media:wms-sys6_mpu_schematics.pdf|System 6 MPU Board Schematics]]
* [[Media:wms-sys6_mpu_bom.pdf|System 6 MPU Board Bill of Materials]]
 
* [[Media:wms-sys7_mpu_schematics.pdf|System 7 MPU Board Schematics]]

===Power Supply===
* [[media:wms-sys3-6_power_supply_early_layout.jpg|Early System 3-6 Power Supply Board Layout]]
* [[media:wms-sys3-6_power_supply_early_schematics.jpg|Early System 3-6 Power Supply Board Schematics]]
* [[Media:Wms-sys3-6-powersupply-assembly.pdf|System 3-6 Power Supply Board Assembly Drawing]]
* [[Media:wms-sys6_power-supply_layout.pdf|System 3-6 Power Supply Board Layout]]
* [[Media:wms-sys6_power-supply_schematics.pdf|System 3-6 Power Supply Board Schematics]]

===Sound Board===

During the long run of System 3 through 7 games, Williams used two basic board types, designated Type 1 and Type 2.

====Type 1 Sound Board====

[[Media:WMS_Sys3-6_Type_1_Sound Board.pdf|System 3-4 Type 1 Sound Board Assembly Drawing and Schematic]]

====Type 2 Sound Board====

The [[Media:Wms-sys6-7-soundspeech-assembly.pdf|System 6-7 Sound & Speech Boards Assembly Drawing]], crafted by Phil Butcher is a great debugging resource.

==Other Documentation==
* [http://www.firepowerpinball.com/ Documentation for Firepower]

==Errors==
===Power Supply===
* Note that the parts bill of materials for some (perhaps all) system 7 games call out a 2N6087 power transistor for Q5. This is most likely a typo. A 2N6057 or 2N6059 should be used.

=Technical Info=

==Proprietary Numbers on Chips==
Some Bally IC chips are marked with proprietary Williams part numbers, and no other markings are present. Below is a list of some of the most common chips found on Williams boards, and the more commonly referred to chip.
*5A-8987 - 6800 CPU chip, Motorola part #SC44216P.
*5A-9150 - 6808 CPU chip
*5A-8972 - 6820/21 PIA chip, Motorola part #SC44067P.
*5A-9903 - 6810 RAM chip

==Backbox Overview==
The Williams backbox is similar for most of the games in the System 3-7 games. System 3-6 remained fairly similar in their backbox layouts. System 7 introduced a number of changes.

* During the beginning of System 7 the transformer moved from the backbox to the lower cabinet.
* The System 7 PSU was redesigned and changed to incorporate a G.I. relay,
* An upgraded System 7 MPU Board was used, which featured a built-in numeric diagnostic display.

The first two System 3 games ([[Hot Tip]] & [[Lucky Seven]]) used chimes and had no sound boards in the cabinet backbox. In the remaining System 3 games and all System 4 games, the sound board was located in the body cabinet, rather than the backbox.

Sample games of the first System 6 game, [[Tri Zone]] had the sound board located in the lower cabinet, but it was moved into the backbox for production games and all other System 6 & 6A games.

For the System 6A game [[Alien Poker]] and all System 7 games, an add-on board sppech board was introduced, which contained additional ROMs for speech.

==MPU Boards==

===System 3===
[[File:WMS sys3 MPU board.JPG|thumb|left|300px|Williams System 3 MPU Board]] 
System 3 was a major step by Williams to digital pinball games. It ushered in the Solid State machines, but to begin with there were problems with acceptance of the new machines.

Williams had the Driver board firing the solenoids on Chime units on the first two System 3 games, and even had a device called a 'noisemaker' (an EM score reel mounted in the body of the game) to provide the sounds of the score reels clicking over! This gave the player the familiar sounds of EM machines which were still around, The player's scoring, their credits remaining and the ball-in-play were all digital and being displayed on the seven-segment gas plasma displays.

Even once they dropped the chimes and 'noisemaker' (for [[World Cup]] in May 1978) and added a digital sound board, the operator could still select the more familiar 'bings & bongs'. A switch was provided on the sound board which allowed selection of simple digital chimes. This option persisted right through on System 3 to System 7 sound boards, but for the most part was not used. Digital sound became more popular as time went on. 

The design of System 3 was based on the Motorola 6800 CPU and what has become a standard arcade peripheral I/O device, the 6821 PIA (originally the 6820). The PIA (or Peripheral Interface Adapter) on the MPU boards was used to drive the display I/O. All other peripherals, switches, lamps, solenoids, and sound, are driven by the 3 PIAs on the driver board.

System 3 and 4 boards use a Motorola 6800 microprocessor with a 6875 clock generator chip, while System 6 and 7 boards use either a 6802 or 6808 microprocessor. You cannot use a 6802 or 6808 in a System 3 or 4 board! The chips are not backwards compatible.
 

====Upgrading a System 3 board to System 4====
[[File:System3ToSystem4ConversionOverview.jpg|thumb|left|300px|Overview of a board converted from System 3 to System 4]] 
A system 3 MPU can be upgraded to use a single 2716 EPROM at what will be IC14 (System 3 schematics do not give this IC position a designation number). This essentially converts the board to a System 4 board. This upgrade is useful to reduce the number of sockets (and failure points). Install a 24 pin socket at the unpopulated area, just to the right of the IC17 socket. Combine the original game ROM code into a single 2716, and install it into the socket of what is now being called IC14. The flipper ROMs are installed in the same locations, ROM 1 into IC20, ROM 2 into IC17. 

[[File:CutJumperWMSSystem3ToSystem4.jpg|thumb|right|300px|IC15 (on left), showing necessary cut and jumper]] 
Procedure:
#Locate IC15 on the MPU (see picture at left)
#Locate the trace that runs from between pins 6 and 7 of IC15 to a via just to the right of the chip
#Sever that trace carefully
#Using jumper wire, connect the through hole via to pin 1 of IC15.
 

Doublecheck the work once the jumper is installed. Perform a continuity test between pin 1 and pin 9 of IC15. There should not be continuity. Conversely, there should now be continuity between pin 1 of IC15, and pin 20 of IC14. 

[[File:WMS Sys3 Remove Components.JPG|thumb|left|300px|Components which must be removed from a stock System 3 MPU board]] 
The System 3 MPU board reset circuit should be updated as follows. This update was recommended by Williams in manual amendment 16P-482-110, and is done to improve CMOS RAM memory content protection during power-on/power-off. 

[[File:Added10K.jpg ‎|thumb|right|300px|10 Kohm 1/4W resistor added to circuit, upper left, connected to the banded end of the zener diode.]]
Procedure:
#Remove C27, R30, and R40 from the upper left corner of the MPU
#Install a 10 Kohm 1/4 watt resistor. One leg of the resistor will be soldered to the cathode of ZR1 (banded side - top). The other leg of the resistor will be soldered to the left through hole where R30 formerly was. The newly installed 10 Kohm resistor is referred to as R96 in System 4 MPU schematics.
 

[[File:1N4148.jpg|thumb|left|300px|Addition of the D19 1N4148 diode installed]] 
Add a 1N4148 diode, if it is not already installed. The location is in the upper left quadrant of the circuit board. The anode (non-banded side) of the diode should be installed in a via, which is just to the right of resistor R23. This via is routed to pin 17 of IC19. The cathode (banded side) of the diode should be tack soldered to the solder pad where the right leg of resistor R23 is installed. Once installed, this 1N4148 diode is referred to as D19 on System 4 MPU schematics. .

[[File:WMS Sys3 MPU Sockets.JPG|thumb|left|300px|Addition of C68 is shown above, a .1uf 50v ceramic capacitor]] 
Install a .1uf 50v capacitor just below the newly installed IC14 socket. One leg of the capacitor connects to +5VDC, while the other leg is inserted into a via which is routed to the /RESET line.
 

[[File:WMS Sys3 Clock Circuit.JPG|thumb|left|300px|A factory board without the recommended capacitor and inductor update.]]
[[File:System3Mod.jpg ‎|thumb|right|300px|The recommended capacitor and inductor additions have been made to this board.]] 
Add a 120pF capacitor (C66) and a 15uH inductor (L1) in parallel with the R1 resistor located just to the left of the crystal. This modification also applies to System 4 boards which do not have these components installed.
 

[[File:WMSSys3CapUpdate.jpg|thumb|left|300px|Here, the originally installed capacitor has been replaced with the correct capacitor.]] 
Finally, some System 3 MPUs came from the factory with a .01uf capacitor (marked 103) installed at position C22, (located just below IC19, the 5101 RAM). If so, replace that capacitor with a .1uf 50v capacitor. The purpose of this capacitor is to snub the high frequency noise created within the 5101 as silicon gates open and close. This applies to System 4 MPU boards too. 

Once the above modifications are performed, a System 3 MPU board will be one-to-one compatible with a System 4 board.
 

===System 4===
[[File:WMS sys4 MPU board.JPG|thumb|left|300px|Williams System 4 MPU Board]]
[[File:WilliamsSystem4MPU.jpg ‎|thumb|right|300px|Another view of the Williams System 4 MPU Board]] 

The System 4 architecture is little changed from the previous System 3 generation. The only functional changes from System 3 to System 4 was a minor alteration to the reset circuit as well as minor changes to the data and address bus in order to more easily facilitate the use of larger EPROMS for the game specific programming.

System 4 machines began with Pokerino in 1978 and ended with Flash in 1979. Late production Flash machines also utilized the then-new System 6 boardset in place of System 4.
 All System 6 software will run on a System 4 board. The exception is Firepower which utilized both the bipolar proms and a 2716 game eprom. Due to the missing memory protection circuit and somewhat unstable clock circuit replacing a System 6 CPU with a System 4 CPU is not recommended.
 

====Upgrading a System 4 MPU Board====
[[File:WMS Sys4 Clock Circuit.JPG|thumb|left|300px|Changed layout with additional capacitor and inductor to the R1 resistor]] 
The System 4 board has a revised clock circuit which usually does not need to be modified. If there are reset problems, replace the 22ufd tantal capacitor with a 33ufd type. This will lengthen the reset period a little and helps the clock circuit to stabilize. The capacitor modification can also be applied to System 3 boards. 

If an incorrect capacitor is installed at position C22, (located just below IC19 - 5101 RAM), it is recommended to replace it. This replacement is only necessary, if a 0.01mfd cap is installed. If so, replace the 0.01mfd capacitor with a .1mfd 50v capacitor. This applies to System 3 MPU boards too. Only early system 4 boards had an incorrect capacitor installed. Also check if the 0.01mfd blocking capacitor for IC14 is missing. If yes stuff it.
 

===System 6===
[[File:SYS-6-MPU-board.jpg|thumb|left|300px|Williams System 6A MPU Board. Note that the .156 headers on this board have been replaced and an LED indicating the blanking status has been added]] 
System 6 was an upgrade to the System 4 design, replacing the 6800 processor with a 6808. They took advantage of the internal clock in the 6808 CPU, removing the need for the 6875 clock generator (a companion chip to the 6800 and now obsolete and impossible to find).

This also changed the way the 'watchdog' circuit functioned. The watchdog monitors the CPU (IRQ signal), and will blank the displays and lamps as well as stopping the solenoids from firing. When something goes wrong (perhaps the MPU board has locked up), 'blanking' should prevent further damage to the game by 'locked on' coils and other output components driven from PIAs on the MPU/Driver boards.

More ROM memory could be addressed, and this was used to hold more sophisticated game code. As an example, Firepower used a 2716 2K Game ROM (which was standard for IC14) plus 3 x Harris bipolar proms (512 bytes each) giving a total game code size of 3,584 bytes. Having just 3K of code space is nothing by today's standards. Programmers had to work hard to get good game code in such a small space.
 

During early System 6 revisions the transceiver chips 8T28 ICs at IC9 and IC10 were found to not be needed. They were eliminated from the design as they didn't need to amplify signals to and from the data bus with modern ROMs. If the ICs are working, leave them alone. But if not, these buffers are obsolete and can be removed and bypassed, in effect by jumpering the data bus pins of the CPU directly to the data bus. i.e. IC9 and IC10 may be removed, and jumpers installed across pins 2-3, 5-6, 9-10, and 12-13 for both ICs.

Also around this period of game development, 8T97 bus "amplifier" ICs at IC3, IC4, and IC8 were used for address and control signals from the 6808 to peripheral ICs. 8T97s are long obsolete too, but fortunately can be replaced with an 74LS367, which Williams itself used in some revisions of the board. 8T97s can not be removed and jumpered like IC9 and IC10. They must be in place. Testing these chips is easy with a logic probe. The input signal should closely match the output signal of the amplifier. i.e. pins 2/3, 4/5, 6/7, 10/9, 12/11, and 14/13 should all test identical with a logic probe. Note that since the signal is amplified, logic probe indicators might vary somewhat. But, the probe should not measure high on one pin and low on the companion pin, for example.

The 8T97 bus amplifiers communicate the following signals.

*IC4 - A0 thru A5
*IC3 - A6 thru A11
*IC8 - A12 thru A15, VMA (valid memory address), and R/W (read/write)

On Firepower alone, the 'Combo ROM' modification must be done to allow the use of a 2732 EPROM as the Game ROM at IC14. This replaces the Firepower game code found in 4 ROMs as described [[Modifying a System 6 or 6A to Use The Firepower 2732 Combo ROM at IC14 | here]], and is an excellent idea. Less chips to worry about, less sockets to replace.

Williams also transitioned to using the updated 6821 PIAs during System 6 because the MC6820 was phased out after 1977.
 

==== Replacing the 6808 with a 6802 ====
[[File:WMS Sys6 Jumper1 6808.jpg|thumb|left|300px|J1 installed for 6808 or 6802 CPU chip]]
[[File:WMS Sys6 R4 6802.jpg|thumb|right|300px|J1 removed, 4.7 Kohm 1/4w resistor (R4) installed for use with 6802 CPU chip]] 
The typically stuffed 6808 microprocessor can be replaced with the more easily obtained 6802 microprocessor. The 6802 uses the same instruction set architecture and pinout, making it "backward compatible" with the 6808. The 6802 incorporates an internal 128 x 8 bit RAM memory. With the proper strapping, the 6810 RAM located at IC13 may be removed when a 6802 is installed. Factory strapping grounds pin 36 of the 6808/6802 socket via jumper J1. Pin 36 must be pulled high by tying pin 36 to 5V via a 4.7K pullup resistor. This enables the 6802's internal RAM. The 6810 at IC13 can then be removed or (if not socketed) simply left in place. 

'''Procedure'''
*Replace the 6808 with a 6802
*Remove jumper J1
*Install a 4.7K resistor at R4

Officially, the 6808 has no internal RAM. But, internally it's identical to the 6802. Sometimes the 6808 internal RAM works but this is not guaranteed, so when using a 6808, be sure pin 36 is grounded.
 

====Factory Jumper on System 6 MPU Board====
[[File:WMS Sys6 Header Jumper.JPG|thumb|left|300px|Williams System 6 MPU board with factory jumper]] 
[[File:WMS Sys3 and 6 Header Compare.JPG|thumb|right|300px|Williams System 6 and System 3 MPU board comparison]]
Some System 6 MPU boards have a jumper installed between IJ3 pin 1 and IJ4 pin 1. This is a factory jumper, and should not be removed. Its purpose is due to the addition of the memory protect circuit, which was incorporated with the System 6 MPU. System 3 and 4 MPU boards did not have a memory protect circuit. The method in which this was added is the addition of pin 1 of IJ4. This pin was formerly the keying pin on System 3 and 4 MPU boards. However, Williams failed to run a trace to this pin for the memory protect circuit. Hence, a jumper was installed. 

If using a System 6 MPU board in a System 3 or 4 game, it is recommended to remove the keying plug from the IJ4 connector in the game, as opposed to cutting / removing pin 1 or IJ4. This will allow the MPU to be used in any System 6 games in the future.
 

===System 6A===
[[File:WMS sys6a MPU board.JPG|thumb|left|300px|Williams System 6A MPU Board]]
The System 6A MPU is a System 6 board without buffer chips at IC9 and IC10. In place of these chips were several jumpers in closed frames, which can look similar to a socket at first glance. The jumpers are used to pass the data lines from the CPU chip to the data bus.

System 6A also used four 7-digit slave displays and one 4-digit slave display driven by a centralized display driver board. This separated the displays from any board logic. Prior to this point, a master display driver board (with a 6-digit or 4-digit glass installed directly on the driver board) housed the display logic and drove four 6-digit slave displays.

Some System 6 boards that are not explicitly marked as 6A in the lower right corner were modified to be 6A boards, which can be identified by the lack of the IC9 and IC10 buffer chips. Either several uninsulated wire jumpers will be installed in the solder pads of these two chips, or the same closed frame jumpers as seen on actual 6A MPU boards may be present.
 

====Modifying a System 6 or 6A to Use The Firepower 2732 Combo ROM at IC14====
[[File:WMS IC14 4700 Res 20 24.jpg|thumb|left|300px|Cuts made, jumper run, and 4.7Kohm resistor added]]
[[File:WMS J3 J4 1N4148.jpg|thumb|right|300px|2 1N4148 diodes added where jumpers J3 & J4 previously were]] 
The factory ROMs for Firepower use all 6 ROM socket positions on a System 6 or 6A board. To minimize the amount of chips and sockets used, some modifications have to be performed to the MPU board. In doing these modifications, the board will then be able to use "standard" green flipper ROM chips at IC20 & IC17, and a single 2732 combo ROM at position IC14. Below are instructions pulled from the readme.txt file, which is included with the Firepower L2 ROM code found on [http://www.ipdb.org/machine.cgi?id=856 www.ipdb.org]. Some of the procedure wording has been altered for clarification.

There are similar methods which may or may not work besides this method. Note that the jumper wire can be connected from IC14 pin 21 to either IC30 pin 14 or pin 36 of the 40 pin interconnect. If at all possible, please make sure that the board being modified boots and works with other game code, such as Gorgar, Flash, or Firepower, before attempting to make these modifications for the Firepower combo ROM. 

#Remove Game ROMs (IC14, IC21, IC22, IC26) from their sockets.
#Remove jumpers that may be installed at J3 or J4 (to the right of IC15, a 74LS139).
#On the solder side of the board, at IC14 pin 21, sever the trace on both sides of the solder pad. Removing the existing solder on the pad may help. The idea is to sever the +5V connection to the pin, while still leaving the solder pad at the pin itself.
#On the solder side of the board, install a jumper from IC14 pin 21 to IC30 pin 14. IC30 is generally not installed. It is a 16-pin chip outline just to the right of IC14 and just above the 40 pin interconnect. Solder the jumper between the hole at pin 14 of the empty IC30 location, and pin 21 of IC14, making sure to not short it to the other side of the trace previously cut at IC14. This connects A11 to IC14.
#On the solder side of the board, install a 4.7K ohm, 1/4 Watt resistor between pins 20 and 24 of IC14. With the resistor leads bent at 90 degrees at a comfortable distance from the body of the resistor, the legs should line up at just the right spacing to solder one lead to each of those pins. Again, make sure to avoid shorting the pin 20 connection to the jumper wire at pin 21, or the cut trace edges around pin 21. This provides a pullup for the active-low chip select.
#Install two fast switching signal diodes (either 1N914 and 1N4148) at locations J3 and J4. The cathode (banded) end should be oriented toward the TOP of the board for both diodes. This enables both of the two Game ROM address ranges to drive the active-low chip select at IC14.
#Program a 2732 with the "FPCOMBO" ROM image and install at IC14. If the board doesn't already have working Green Flipper ROMs at IC17 and IC20, those should be installed also. Note the orientation of the ROMs with respect to pin 1 of the chip sockets.
 

===System 7===
[[File:Sys7-MPU.jpg|thumb|left|300px|Williams System 7 MPU Board]]
System 7 was considered a major step change. It had a redesigned MPU board, now supporting a single 7-segment LED display for indicating improved diagnostic information instead of the original 2 LEDs that System 3-6a MPU boards had used. It also added commas to the player scoring displays and moved the sound select support to the MPU board. An extra 6821 PIA supported both the sound/speech selects and the display of commas. An extra 12-pin header at 1J8 was added to provide connections for the new Sound and Commas support. This freed up five solenoid drives at positions #9-13 on the Driver board, which had been sound/speech selects. They were then available to drive extra game Coils or Flash Lamps.

The MPU used two 2114 Static RAMs; these 1024 x 4 bit RAMs replaced the use of 6810 RAMs mentioned above. There was extended memory addressing, support for multiple 2732 ROMs (or EPROMS) as standard and a huge number of jumper selections available. The jumpers support various memory addressing schemes and ROM sizes, making the System 7 board MPU "backwards compatible" and able to emulate any of the previous System 4-6a games. (Provided, of course, that the correct Jumper Settings and EPROMS are installed.)

The Sound and Speech boards were unchanged for System 7; both sound and speech boards remained compatible from their introduction for Gorgar. In some cases the System 7 game had no 0.100" 40-way IDC header for the speech board connection. This was a cost saving measure made by Williams for games produced without speech. This connector is cheap and available today as it is still used for PC IDE hard drives and modern PCB connections. Adding this connector back to the sound board allows it to support a speech 'daughter board' by removing the Jumper at W1.

The Driver Board mates with the MPU board using 40 x 0.156" header pins on the MPU and female sockets on the Driver Board. This is a continual source of repair problems for this era of Williams machines. To solve this, when designing System 9 Williams combined the MPU and Driver Boards (and the Sound Board) onto a single PCB (Printed Circuit Board), and removed the problems associated with the now infamous Williams "40-way" connector. Only the speech board remained separate, as digital speech was considered an optional feature.
 

====System 7 MPU Jumper and IC Locator====
[[File:WMS Sys7 MPU Jumpers Marked.JPG|300px|left|thumb|Positions of the jumpers on a System 7 MPU board]]
[[File:System7ICLocator.png|300px|right|thumb|IC Locations on a System 7 MPU board]]
System7ICLocator.png
 
The image at left shows the most common jumpers on a System 7 MPU board. There are other jumpers on the right hand side of the board (not shown in the pic). However, these jumpers are rarely added or removed, nor do they pertain to the size of the ROM chips installed on the board.

The image at right is provided to assist in IC location.
 

The factory release of most System 7 MPUs contained a 2532 PROM at IC17. The more common 2732 is easy to use, with minor board modifications.

[[File:WMSSystem7MPUJumper.jpg|300px|left|thumb|Component side of a System 7 MPU board with modifications for a 2732 at position IC17]]
[[File:WMS Sys7 MPU 2732 IC17 Mod.JPG|300px|right|thumb|Solder side of a System 7 MPU board with modifications for a 2732 at position IC17]] 
#'''On the component side of the board,''' move jumper 22 to jumper 23. This amounts to moving the jumper down one position.
#'''On the solder side of the board,''' cut the fat trace that grounds pin 21.
#Jumper from the via labeled "22" to pin 21 of IC17. Be sure that the jumper doesn't short to the jumper previously moved on the component side.
 

====System 7 MPU Test Pad Info====

There is an unpopulated connector in the lower right corner of the system 7 MPU board. You can use a meter or logic probe to test the signals that are present on it or possibly add a connector to it (you can use a .100 dual row 20x2 connector).

[[file:Williams-sys7-unpopulated-connector.jpg|thumb|left|300px|Unpopulated Connector]] 

{|class=wikitable
|-
|gnd || 40 || 39 || gnd
|-
|d7 || 38 || 37 || ic36 CA2
|-
|d6 || 36 || 35 || ic37/15
|-
|d5 || 34 || 33 || ic37/14
|-
|d4 || 32 || 31 || ic37/13
|-
|d3 || 30 || 29 || ic37/21
|-
|d2 || 28 || 27 || ic36 pb4
|-
|d1 || 26 || 25 || ic36 cb2
|-
|d0 || 24 || 23 || blanking
|-
|reset || 22 || 21 || vma
|-
|r/w || 20 || 19 || bus 02
|-
|a14 || 18 || 17 || a15
|-
|a12 || 16 || 15 || a13
|-
|a10 || 14 || 13 || a11
|-
|a8 || 12 || 11 || a9
|-
|a6 || 10 || 9 || a7
|-
|a4 || 8 || 7 || a5
|-
|a2 || 6 || 5 || a3
|-
|a0 || 4 || 3 || a1
|-
| +5vdc || 2 || 1 || +5vdc
|-
! colspan="4" | Bottom of board
|}

===MPU Compatibility===
Williams 3-7 MPU are pretty flexible. With some modifications, boards can be upward compatible, while others are downward compatible.

Here are the details:
*A System 3 MPU can be upward compatible to a System 4 MPU, if the upgrades are performed as described [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Upgrading_a_System_3_board_to_System_4 above]. And if a System 3 MPU is upgraded to a System 4 MPU, it is then upward compatible with a System 6 MPU board. There will not be a memory protect circuit though. 
*System 4 and 4A MPUs are upward compatible to a System 6 MPU, when a socket is installed and used at position IC14. However, there will not be a memory protection circuit. A System 4 MPU is backward compatible with a System 3 MPU with no modifications performed. 
*System 6 and 6A MPUs are backward with System 3, 4, and 4A MPU boards with no modifications performed. 
*A System 7 MPU is backward compatible with System 3, 4, 4A, 6, and 6A MPU boards. However, board jumpers will have to be removed / installed. It not recommended to use a System 7 MPU board in any previous systems, but it can be done. 
*System 3, 4, 4A, 6, and 6A MPU boards are '''not''' upward compatible with System 7 MPU boards.

In any instance where a non-native MPU board is used in place of the original MPU board, the correct flipper ROMs and game ROM must be installed. An example would be if an upgraded System 3 MPU were to be used in Gorgar. The GREEN flipper Roms and Gorgar game ROM would have to be installed in postions IC20, IC17, and IC14.
 

===Aftermarket Boards===

[[File:RottendogMPU327.jpg‎|300px|thumb|left|A Rottendog MPU327, which can be installed in any Williams System 3 - 6 game.]]
[[File:MPU327StuffedWrong.jpg‎|300px|thumb|right|U17 on an MPU327, stuffed correctly with a 74HCT9114.]]
[http://www.rottendog.us/?product=mpu327 Rottendog] offers aftermarket Williams 3 through 7 combined MPU/driver boards. The Rottendog board (pictured left) contains all the game code for every System 3 through 6 game. The game code is DIP switch selectable. Note that the "sense" of the DIP switch bank is backwards. Follow the on-board silkscreen to the left of the DIP switch. 
'''Note: as of January 2018, Rottendog is no longer claiming support for System 7 games with their MPU327 board.

Some '''older''' Rottendog MPU327s were stuffed wrong at the factory. U17, which services the switch columns, should be stuffed with a 74HCT9114. In some boards, that location is stuffed with a 74HCT244, which will not work correctly. Note that there are several revisions of the MPU327 board.
 

[[File:RottenDogMPU327Short.jpg‎|300px|thumb|left|A Rottendog MPU327, installed, and shorted to a switch matrix header pin. Image provided by Tony, PinSider "goingincirclez". Used with permission.]]
[[File:RottenDogMPU327ShortCorrection.jpg‎|300px|thumb|right|One user's (excellent) correction for the situation. Image provided by Tony, PinSider "goingincirclez". Used with permission.]] 
The RottenDog MPU327 PCB design causes the switch matrix row header (2J3) to short to a mounting bracket as shown at left. This can cause the switch column IC at U17 to fail. A simple correction for this issue is shown at right. See the [https://pinside.com/pinball/forum/topic/warning-to-rottendog-327-owners-check-it-now original Pinside thread] for additional details.
 

[[File:RD 327 MPU Combo Dipswitch.jpg|300px|thumb|left|Rottendog MPU327 game select dipswitch bank]] 
Note that the dipswitch bank used for selecting a specific game has 8 dipswitches, whereas only the 6 switches on the right are the only ones used. The 2 left dipswitches must be turned "on" (opposite of what is expected of a dipswitch) to "0".
 

==Driver Boards==
===System 3-6===
[[File:WMS Sys3-6 drvr.JPG|thumb|right|300px|Williams System 3-6 Driver Board]]
The driver board uses three 6821 Peripheral Interface Adapter (PIA) chips to drive:

* an 8x8 Matrix for the Lamps
* an 8x8 Matrix for the Switches
* Solenoids and Sound Selects

More properly, the PIAs were used to drive transistors that in turn drive the lamp matrix, switch matrix, and solenoid circuits. In the case of the solenoids, Darlington transistors are used as "solid state relays", providing a path to ground for coil power, causing them to energize.

The electronic design choices Williams made became the basis for all subsequent Bally/Williams pinball games and even games being made today. The specific CPU and PIA ICs may change, more memory and ROM space is available to the programmers, MOSFETs are used as the switching relays instead of transistors...yet the basic design established for the lamp matrix, switch matrix, and for energizing coils, remains unchanged.
 

===System 7===
[[File:WMS Sys7 drvr board.JPG|thumb|left|300px|Williams System 7 Driver Board]] 
The driver board remained almost completely unchanged from System 3 right through to System 7 with the exception of one small change that was made to the driver board during System 7. Eight resistors were changed to zero-ohm jumpers in the switch matrix inputs to increase sensitivity and responsiveness. These zero ohm resistors are located in the upper right corner of the driver board.
 

===System 7 Hyperball Specific Driver Board===
[[File:HyperBallSpecificDriverBoard.jpg|thumb|left|300px|Williams System 7 Hyperball Specific Driver Board]] 
Since Hyperball didn't need to drive coils other than the cannon coil and the auger motor, and since it needed to drive many more lamps than a normal pinball game, Williams created a unique, special purpose variant of the driver board specifically for Hyperball. This driver board can only be used in Hyperball, and a regular System 3 through 7 driver board can NOT be used in Hyperball.
 

==Power Supplies==
[[File:WMS_Early_Sys3_Power_Supply.jpg|thumb|300px|left|Early Williams System 3-6 Power Supply]] 
The System 3-6 power supply used in [[Hot Tip]] and [[Lucky Seven]] have a few additional components that later games did not need, physically located a little above the row of four fuses: two .22mfd mylar capacitors and two 1N4001 diodes. If a later power supply is being installed in Hot Tip or Lucky Seven, these components must be added to the board if they are missing.

Williams continued to populate these components for several following games, but they were not utilized. These components can be safely left populated or simply removed from the board. 

[[File:WMSSystem7PowerSupply.jpg|thumb|300px|left|Williams System 7 Power Supply (GI input connector modified from stock)]] 
Note that the parts bill of materials for some (perhaps all) system 7 games call out a 2N6087 power transistor for Q5. This is most likely a typo. A 2N6057 or 2N6059 should be used.
 

==Flipper Power Supply==
<center>
<gallery widths=400px heights=200px perrow=2 caption="Williams System 7 C-9939 50V Flipper Power Supply Board">
File:C-9939-Front.jpg|<center>Front</center>
File:WMS-C-9939-Back.jpg|<center>Back</center>
</gallery>
</center>
This PCB was first used in Hyperball to control the auger (ball lift) motor. As seen in the pictures above, the PCB layout was designed to accommodate more components than were ever stuffed. This is because this same board, using different components, is used in some Williams video games. In Firepower II, Laser Cue and Star Light the trimmed down version shown here provides the flipper coils with 50VDC power. The AC voltage supplied to the bridge rectifier originates from a second, smaller, transformer mounted on the wooden plank in the bottom rear of the cabinet.

Since the coil voltage this board provides is exactly the same as that of later System 11 games, far stronger Williams coils, such as the FL-11630, can be used in these games. It's advisable when using these coils to install a 2.2µF capacitor across each EOS switch, to reduce spark across the EOS switch, as was done in later Williams System 11 games.

The board suffers from cold solder joints at the header pins (at least). As shown in the picture above, someone did a (poor) job of reflowing the solder on the header pins. A better solution would be to replace the header pins altogether.

The exact same board is used in all System 9 and early System 11 games up until F-14 Tomcat. Data East copied this design. Hence, this 50VDC Power Supply can be used in Data East games from Laser War to Time machine.
 

==Sound Boards==

During the long run of System 3 through 7 games, Williams used two basic board types, designated Type 1 and Type 2

===Type 1 Sound Board===

[[File:WMSType1SoundFront.jpg|300px|thumb|left|Williams Type 1 Sound Board front]]
[[File:WMSType1SoundBack.jpg|300px|thumb|right|Williams Type 1 Sound Board back]] 
The Type 1 sound board is rectangular in shape as pictured at left. Two versions of this board were manufactured. One version placed the 12,000uf 5V filter capacitor vertically. The other version placed the same capacitor horizontally. The boards function identically.
 
As can be seen on the back of the board pictured at right, the board was modified from the factory to add 3 jumpers (the three longer red wires) to make it work correctly. Every Type 1 sound board should have these jumpers. Note: The factory installed jumpers take advantage of trace "vias" to accomplish these connections.

#A long jumper that connects the reset pins on the 6821 PIA (pin 34) and the 6802 (pin 40)
#Pin 40 of the 6802 also needs to be jumpered to pin 36 of the 6802 for the reset circuit to be complete.
#Jumper pin 35 to pin 8 of the 6802. This ties Vcc1 and Vcc2 together.

Williams documented additional modifications in the "Flash" manual. The board pictured has been updated with all of these modifications. A drawing of these modifications and jumpers can be found [https://www.pinwiki.com/wiki/images/d/d5/Sojueen.pdf here].

The modifications are:
#Add a jumper between pins 39 and 40 of the 6821 PIA
#Add two 10K, 1/4W resistors
#(Possible) replace two 100K resistors with 4.7K, 1/4W resistors. Note that some boards shipped with 4.7K resistors installed.

'''Modifications 1 and 2''' "reduce the susceptibility of the sound board to noise". The "noise" can cause the board to stop execution after a short time, especially when using a 9316B or 2716 ROM. If a sound board makes sound after pressing the diagnostic button, but either makes no other sound, or makes sound for a short time and then quits, these two mods will probably fix this problem.
'''Modification 3''' "improves the quality of the sound produced at the speaker".

'''Theory of Operation'''

The Type 1 sound board is about as basic as a sound board can be.

*A 3.58Mhz crystal provides the clock signal across pins 38 and 39 of the 6802.
*A simple reset generator is configured with Q1, Q2, and CR3 (a 6.8V zener diode). As the unregulated 12VDC rises past 6.8V, the zener breaks down, eventually allowing pin 40 of the 6802 to be pulled up to logic high (5V).
*A diagnostic pushbutton, upper right, grounds the NMI (non-maskable interrupt) signal to the 6802 processor and causes the board to play a diagnostic tune (in most cases).
*A two position switch selects between "sounds" (right) or "chimes" (left).
*A volume adjustment POT is located on the board itself, and is a 5K POT.
*A 6802 microprocessor controls the board via a 6821 Peripheral Interface Adapter (PIA).
*The board does not have a RAM IC (like a 6810). Instead, the built-in 128 bytes (yes, 8-bit bytes) of RAM on the 6802 are used.

Power is provided from the transformer secondary at connector 10J1.

*Pins 1,2 - 9VAC
*Pins 5,6 - Ground (center tap)
*Pin 7 - Key
*Pins 8,9 - 9VAC

Power is fused and rectified via the "in-line" bridge rectifier immediately below the connector.
Positive unregulated 12VDC is filtered by a 12,000uf/25V electrolytic capacitor.
Negative unregulated -12VDC is filtered by a 1,000uf/25V electrolytic capacitor.
The positive unregulated 12VDC is regulated down to 5VDC via a 7805 regulator at IC11.
These three voltages, plus ground, define the power requirements for the board.

A speaker is connected to 10J2, positive to pins 1/2, ground to pins 3/4.

Sound selects are presented by the driver board to the sound board at connector 10J3. Selecting a particular sound is a matter of grounding the appropriate sound select pins which are normally held high via 4.7K pullup resistors at R37 through R44. Each signal is buffered via the 4050 non-inverting hex buffers at IC8 and IC9.

Each of the sound select signals is connected to both a 4068 8-input NAND gate and to the (software configured) input port of the 6821 PIA (PB0-PB7). The output of the 4068 is connected to pin 18 (CB1) of the 6821 which is configured by the sound board software to create an interrupt to the 6802 processor. When the 6821 PIA interrupts the processor, the interrupt servicing routine reads the input port (PB0-PB7) of the PIA to determine which sound was commanded. The processor pulls sound data from the sound ROM and pushes the data to the 6821 PIA (software configured) output ports (PA0-PB7) one 8 bit byte at a time. The PIA output port signals drive a simple 1408 DAC (digital to analog converter) which produces the analog signal that is stabilized and eventually amplified by a TDA2002 audio amplifier.

'''What Goes Wrong'''

The Type 1 sound board shares most of the common faults associated with the Williams System 3-7 board set. Chief among them are:
#ScanBe sockets. These are well documented to be long past their useful life and should always be replaced.
#Fractured solder joints at the header pins. The Williams manufacturing process trimmed the .156 header pins too short, damaging the solder meniscus. Over time, these solder joints develop fractures. The header pin eventually begins to work itself out of the joint which causes reliability issues.
#Aged electrolytic capacitors. At the very least, the 12,000uf/25V 5VDC filter capacitor should be replaced. Replacing all of the electrolytic caps is advised. Following is the capacitor parts list.

'''Electrolytic Capacitors Used'''

*C10 - 25uF, 25 Volt Axial (can use 22uf)
*C13 - 500uF, 16 Volt Axial (can use 470uf)
*C14 - 800uF, 16 Volt Axial (can use 1000uf)
*C27 - 100uF, 10 Volt Axial
*C29 - 12000uF, 16 Volt Axial
*C30 - 1000uF, 16 Volt Axial

[[File:WMSSystem3-4RectangularSoundBoard.jpg|300px|thumb|left|Williams Type 1 Sound Board Version 2 with the horizontal cap, front]]
[[File:Type1soundBoardHorizontalCapBack.jpg|300px|thumb|right|Williams Type 1 Sound Board Version 2 with the horizontal cap, back]] 
These images show a Type 1 sound board that was introduced later in production. The 5VDC filter capacitor was turned horizontally. Also, an extra connector was added to enable a remote volume POT. Note that this sound board has been "recapped".

This revision of the sound board picked up the jumper modifications of the earlier board in the PCB design, with one exception. Pins 39 and 40 of the 6821 need to be bridged (or jumped) to avoid the board locking up after a short (and random) period of time. A solder bridge can be seen at pins 39 and 40 of the sound board pictured at right.
 

[[File:WMSType1SoundBoardJumper.jpg|300px|thumb|left|Williams Type 1 Sound Board Version 2, closeup of jumper to enable onboard sound POT]] 
Later production Type 1 sound boards added a connector to enable a remote volume POT. If the remote POT is not used and the onboard POT is used instead, a jumper must be installed between pins 1 and 2 of this connector. The pictured jumper is quite Gucci. A simple wire jumper on the back of the PCB will suffice.
 

====Type 1 Sound Board Jumpers====
[[File:WMSType1SoundFront.jpg|300px|thumb|left|Williams Type 1 Sound Board]]
The Type 1 Sound board can be jumpered to use a 7641 masked ROM, a 9316B masked ROM, or a 2716 (or doubled 2732). The board pictured at left is jumpered to accept either at 9316B or a 2716. To use a 7641 masked ROM, remove the four jumpers to the right and just below the sound ROM, and install the opposite set of four jumpers. 

===Type 2 Sound Board===
<center>
<gallery widths=400px heights=400px perrow=2 caption="Williams System 6-7 Type 2 Sound and Speech Boards">
File:WMS Sys6-7 sound.JPG|<center>Williams System 6-7 Type 2 Sound Board</center>
File:WMS Sys6-7 sound speech.JPG|<center>Williams System 6-7 Type 2 Sound Board with Speech Board Connection</center>
File:WilliamsType2SoundAndSpeechBoarfPair.jpg ‎|<center>Williams System 6-7 Type 2 Sound Board with Speech Board. Note that this -3 revision board features a tantalum capacitor soldered directly between test point 1 (+12VDC) and test point 3 (ground). In later board revisions, this part was added to the PCB design.</center>
</gallery>
</center>

==Speakers==
With the exception of Hot Tip and Lucky 7, all Williams System 3-7 games use a speaker. And, nearly all of them use a single 6-1/2" speaker located on the cabinet bottom (later games, like Firepower II, had an oblong speaker below the smaller backglass instead). Speakers used during games such as Firepower were 8 ohm 5 watt.
 

==Displays==
[[File:WMS sys3-6 master display.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Using UDN7180A - Common)]]
[[File:WMS Sys3-6 Master Display NE584.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Using NE584 - Less Common)]]
[[File:WMS sys3-6 master display discrete.JPG|300px|thumb|left|Williams System 3-6 Master Display Board w/ Discrete Components]]
[[File:WMS-SYS6-displays.jpg|300px|thumb|left|Williams 6-Digit Slave Displays]]
[[File:WMS sys6a-7 display drvr.JPG|300px|thumb|left|Williams System 6A-7 Display Driver Board]]
[[File:WMS-SYS7-displays.jpg|300px|thumb|left|Williams 7-Digit Slave Displays]]
[[File:Bowler6DigitFace.jpg|300px|thumb|left|Williams 6-Digit Puck Bowler Display Glass]]
[[File:Bowler6DigitBottom.jpg|300px|thumb|left|Williams 6-Digit Puck Bowler Display Edge Connector]]
 

==Other Boards==

==Flippers==

==Drop Target Banks==
===First Generation Drop Target Bank===
[[File:WMS Horseshoe Drops.JPG|200px|thumb|left|Typical first generation Williams solid state drop target bank (Time Warp)]]
Starting with the first Williams solid state game, Hot Tip, Williams introduced their version of the solid state drop target bank. Drop target banks were a rather new design for Williams. They were the last major pinball manufacturer to introduce the drop target bank earlier in 1977 with the electromechanical game, Big Deal. And, only 3 games prior to the solid state version of Hot Tip, including the electromechanical version of Hot Tip, were manufactured with drop target banks. 

The reason for mentioning the background regarding Williams drop target banks is because of the actual design implemented. There is one distinct difference between Williams drop target banks and any other manufacturer's drop target bank. In addition to using a scoring switch for each drop target in a bank, Williams used a secondary set of switches paired in series to detect when all of the drop targets were physically dropped. The drop target bank frame, reset coil or coils, appearance of the drop target faces on the playfield, and operation of the bank was virtually the same between Williams electromechanical games and solid state games. Therefore, it is believed that Williams designed their banks this way, because they had not been designing drop target banks that long, and decided upon a legacy approach. In other words, the Williams solid state drop target banks used hardware instead of software to detect when all the drop targets were down.
 

[[File:WMS Horseshoe Drops Back.JPG|200px|thumb|left|Backside of Williams first generation drop targets]] 
The design of the drop targets are very different from any other manufacturer's design. Unlike Bally, Stern, or Gottlieb, the Williams drop target is a meaty, reinforced plastic which is fairly consistent in thickness and width throughout the target. Williams does not use a face with a long neck stemmed down in size. The benefit to this design is that breakage is minimized. The downside to this design is extra added weight. There are several other design differences too, such as the compression spring used to pull the target down. It is physically screwed to the front of the drop target plastic, as opposed to being attached via a molded "hook" like other manufacturers. This too is a plus, because the molded hooks on other drop target systems are prone to breakage. However, probably the most recognizable difference is the drop target switch design. On the back side of a Williams drop target, a switch triggering mechanism in the form of a copper horseshoe with two contacts is physically screwed to the plastic. The combination of the horseshoe contacts and discrete circuit boards for each target mounted to the bank of the bank are what is used to detect the three states of the drop target position.
 

[[File:WMS Drop Anim.GIF|150px|thumb|left|Simulation of the three different states of a Williams drop target]]
A simulation of the operation of a Williams drop target switch can be viewed at the animation located to the left. As mentioned before, the horseshoe contact is attached to the backside of the drop target plastic. The horseshoe contact makes physical contact with the thick copper or tinned traces of the circuit board, which is secured to the backside of the drop target bank. 

An explanation of the three different states of the drop target are:
#When the horseshoe contact is located at the uppermost set of traces, the first frame in the animation, the drop target is in the upright position (fully reset).
#Once the drop target face is struck by the ball, the drop target plastic is pushed from the metal ledge of the metal drop target frame. As the drop target falls, the horseshoe contacts slide over a second set of traces on the circuit board, as seen in the second frame of the animation. These contacts are tied to the switch matrix via a switch strobe and return line respectively. The switch strobe line is common to all drop targets in the bank, while each drop target in a bank will have its own switch return line. Each switch pair is used for scoring purposes.
#Finally, the drop target will fully drop, and the contacts come to rest on a third set of traces on the circuit board. This set of traces is tied in series from one drop target circuit board to the other. Because the pairs of traces for each target are tied together in series, a switch, secondary to the individual scoring switches is used. Once all of the targets in the bank are dropped, the series switch circuit is complete. The switch matrix detects this as a single switch closure. In turn, the drop target bank is reset.
 

[[File:WMS Horseshoe Drop Bank Marked.JPG|200px|thumb|left|Switch solder points identified on a drop target bank]] 
With the maze of similar-colored wires on the back of a Williams first generation drop target bank, it can be somewhat intimidating as to what wire goes where. The switch return lines (white wires with colored traces) attach to the solder tabs of the eyelets. Likewise, the non-banded side of the diode attaches to the same solder tab of the eyelet. The switch strobe line (green wire with a colored trace) can be attached to any of the points circled in green. On the bank in the adjacent pic, the switch strobe wire was attached to the green circled area on the far right. The black and gray wires are sometimes substituted with different colors like yellow.
 

===Second Generation Drop Target Bank===
[[File:WMS Leaf Drops.JPG|thumb|200px|left|Typical second generation Williams drop target bank]] 
Starting with Black Knight, Williams slightly changed the design of the drop target bank. Instead of using horseshoe contacts and circuit boards for switch detection on each drop target, the horseshoe contacts were replaced with a copper leaf spring and the discrete circuit boards were replaced with leaf switch stacks. Detecting when all the drop targets down was now handled via software. There are subtle physical differences in the drop target plastic. The most obvious difference is the thickness of the bottom of the drop target. The thickness was increased to compensate for the use of bottom mounted leaf switches.
 

===Third Generation Drop Target Bank===
+++ Need pic of drop target bank with microswitches +++ 
The third and final generation of System 3-7 drop target banks are essentially the same as the second generation. The main difference is that microswitches were used to detect when a drop target drops versus leaf switches.
 

==Additional Diagnostics - Pincoder test ROMs==
A comprehensive set of free, third party diagnostic/test ROMs can be found here: http://pincoder.ca

These ROMs can be used in-game to test individual components of your pinball machine. Additionally, the RAM and CMOS tests thoroughly check all addressable locations within each chip, resulting in extremely accurate results.

Support for these ROMs can be found on Pinside here: https://pinside.com/pinball/forum/topic/new-williams-system-6-in-game-test-roms

=Recommended Modifications=

==Additional Fuses==
[[File:WMS_Sys6_Fused_Bridges.JPG|left|thumb|300px|Fuse holders with 8 amp slo-blo fuses added to one of the AC inputs to each of the bridge rectifiers. (Firepower)]]
[[File:WMS 3-7 Fused Bridges Inline Butt Connectors.jpg|right|thumb|300px|Inline fuse holders installed with solderless crimp butt connectors]] 
Williams failed to include fuses in the AC connection between the transformer secondary and the solenoid and controlled lamp bridge rectifiers. In theory, the primary power fuse should blow if one of these bridges short. However, this is not always the case. Sometimes, the bridges short in such a manner that the wiring from the transformer secondary to the bridge becomes the fuse, and the wiring insulation melts until something gives.

This problem can be addressed by adding 2 fuse blocks and two 8 amp slo-blo fuses. For each bridge, afuse is added between either transformer secondary wire and the bridge. The AC inputs to the bridge are both marked with a 'tilde' on the BR which looks like an 'S' on it's side: '''~'''. The wire colors are typically red for solenoids, and blue for the controlled lamps. However, it is best to consult the game schematics to confirm.

Although the preferred method is to put fuse holders on the backbox wall, installing fuses in any configuration is paramount. One way is to use inline fuse holders, and solderless crimp butt connectors. This is a quick and easy alternative, even though it may not be the prettiest solution.
 

[[File:FirePowerAdditionalFusing.jpg|left|thumb|300px|The Firepower schematics, updated to include two 8ASB fuses between the transformer secondary and both the solenoid and controlled lamp bridge rectifiers.]] 
Williams incorporated an 8A normal-blo fuse in later games (Big Guns and newer), while Data East chose to install 8A slo-blo fuses.

A nice solution for this problem is the Inkochnito Bridge Board that can be found at this link: http://www.inkochnito.nl. Click on the Bridge Board image for more information.

System 3 and System 4 games did not incorporate a fuse for the 9.3VAC supply lines. If either diode D7 or D8 shorts, something in the circuit will act as a fuse. Sometimes, a board trace acts as a fuse under these conditions. It is much, much better to add two 4 amp slo-blo fuses directly after the transformer, just as Williams did when System 6 games were introduced.
 

==MPU Batteries & Memory==

===Relocating the batteries away from the MPU board===
[[File:Leaking_Battery.jpg|120px|thumb|left|Leaking Battery]]
Relocating the 3xAA batteries from the MPU board is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. Sometimes the battery terminals don't look corroded, but the metal rivet which contacts the battery are actually missing. 

If "04 00" is displayed in the credit/match display, rather than the game going into attract mode, then the game is in audits mode:
* The batteries have failed and need replacing
* The battery voltage is not reaching the 5101 CMOS RAM (check Test Point TP7, which should measure 4.3v with the power on and 3.9v (or so) with the power off.
* Blocking Diode D18 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There is another problem holding settings, such as a faulty 5101 CMOS RAM.

Simply removing the batteries is not really an option as the game will not boot directly into "attract mode" when switched on. It also will not retain the settings such as the number of balls per game, the free play setting (usually obtained by setting maximum credits to 0), or high scores It's possible on System 3-7 games to switch the game off, and then quickly back on to go from the '04 00 audit mode' to attract mode. Credits would still need to be added by the coin switches.
 

===Remote Battery Pack===

One option is to remotely locate the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) any circuit board (see driver board pic below). Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually.

Adding a connector between the battery pack and the MPU board is a good idea, so the pack can easily remove the battery pack from the board. Plus, it the batteries are forgotten and do leak, the MPU board will not have to be removed to add another battery pack. Another solution is to buy a battery holder with the 'transistor radio' type connector which can be snapped on and off. Just be very careful if using this style of connector. Adding a tag noting that a '''9 volt battery should never be connected''' is a very good idea. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is a available, a diode or jumper can be soldered in the first position. A diode is the preferred approach, as this will prevent the batteries from being charged and 'cooked' by the game if blocking diode D17 on the MPU board fails. Keep in mind that an added secondary diode to this circuit will decrease the voltage passing to the 5101, if D17 is still good. Locate a 1N4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the Red wire and towards the (+) terminal marking on the MPU board.

The game takes 3 x AA Batteries, so it uses at least 4.5v total. However, it will still store settings down to about 3v or so. After that an AA battery's life will taper off very quickly. A fresh set of batteries should last for at least a year, or the is some other issue. If the 5101 CMOS RAM is socketed, it's possible that it isn't the low power version. Or, possibly the D17 diode has shorted.

The images below illustrate how to install the wiring for battery packs on the different MPU Boards.

[[File:WMS_sys4_MPU_board.JPG|300px|thumb|left|Williams System 4 MPU Board]] 
On the System 4 MPU, solder the battery cables: Ground (Black Wire) to the Bottom Left pad and Positive (Red Wire) to the Top Right.
 

[[File:WMS_sys6a_MPU_board.JPG|300px|thumb|left|Williams System 6 MPU Board]] 
On the System 6(a) MPU, solder the battery cables: Ground (Black Wire) to the Top Right pad and Positive (Red Wire) to the Bottom Left.
 

[[File:WMS_sys7_MPU_board.JPG|300px|thumb|left|Williams System 7 MPU Board]] 
On the System 7 MPU, solder the battery cables: Ground (Black Wire) to the Bottom Left pad and Positive (Red Wire) to the Top Right.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the (+) and (-) pads of the MPU board. All battery packs are pretty cheaply made, and failures "out of the box" can be somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.

Another good practice, while the MPU board is already out, is to check the D17 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the 5101 non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. If Alkaline batteries are charged, they will be damaged and fail, leak, or (in extreme cases) explode. Testing the D17 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D17 diode with a 1N4148, or add a secondary 1N4004 to the battery pack. Once again, if a secondary diode is added, it will decrease the voltage passing to the 5101, if D17 is still good.

[[File:Wms drvr bat dam.JPG|300px|thumb|left|Alkaline Damaged Williams Driver Board]] 
It is important to remotely relocate the batteries from the MPU board, unless using a lithium replacement. The potential is there for not only the MPU to become damaged, but other associated boards in the backbox. The pic to the left is a prime example of extended damage. The damage occurred in this instance, because the shuffle bowler this board came from was stored with the batteries still on the MPU board for an extended period of time (roughly 5-8 years). It's a costly shame, because this was an otherwise decent, clean, working driver board. The amount of repairs which have to be performed now are going to be extensive.
 

===Installing a Lithium Coin Cell Battery Backup===
An alternate solution to a remotely located battery pack is to use a single CR2032 battery and holder mounted on the MPU. Lithium button batteries do leak, although not nearly as commonly or as severe as alkaline batteries. And, since the battery will be contained in a holder mounted above the PCB, there is little risk of corrosion attacking the board.

The holder and replacement batteries are inexpensive. 
The following photo gallery shows the installation procedure. 
This method can be adapted to work with all Williams System 3-7 MPU board.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Williams System 4 MPU Coin Cell Installation">
File:System4MPUCoinCell-1.jpg |<center>Small hole drilled at intersection of holder pin "arc" and trace on board solder side.</center>
File:System4MPUCoinCell-2.jpg |<center>Battery holder installed, front side. Note the "zero ohm jumper" soldered between the top left and top right battery holder holes.</center>
File:System4MPUCoinCell-3.jpg |<center>Battery holder installed, rear side. Note the negative connection marked lower right and the path of the positive connection.</center>
</gallery>
</center>
 

===Installing a Memory Capacitor (SuperCap) Instead of Batteries===
Another alternative is to install a memory capacitor. In essence, a memory capacitor is similar to a rechargeable battery, although, the likelihood of a memory capacitor leaking is minimal compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off, the memory capacitor slowly loses its charge over time. Therefore, it is imperative that the game periodically be turned on to allow the capacitor to charge up to its full capacity again. If a game will not be turned on for long lengths of time, a memory capacitor may not be the best solution.
 

====System 3/4====
[[File:System3-4SuperCap.jpg|300px|thumb|left|5.5V 1F Memory Capacitor Added to a System 3 MPU Board.]] 
When installing a SuperCap, the polarity of the cap needs to match the battery pad polarity. Connect the negative lead of the cap to ground. In the picture at left, the old top center battery holder connection was leveraged as an attach point. A jumper (not shown) on the back of the board connects from there to the edge of board ground.

Connect the positive lead to the the upper right battery holder connection through hole.

Remove D18 and replace with a 100ohm 1/4W resistor.

Once the capacitor is installed, and the board installed back in the game, leave the game powered on to allow the game to charge the capacitor fully. After that, turning the game on monthly for about 10 minutes allows the capacitor to recharge.

 

====System 6====
[[File:WMS Sys6 Mem Cap.JPG|300px|thumb|left|5.5V 1.5F Memory Capacitor Added to a System 6 MPU Board. Labels added to help locate parts.]] 
When installing a SuperCap, the polarity of the cap needs to match the battery pad polarity. Connect the negative lead of the cap to ground. Connect the positive lead to the banded side of diode D18 (1N5817). The picture to the left shows a jumper added to connect the negative lead of the cap to ground on a System 6 MPU board.

As an alternative to running the positive lead of the cap to diode D18, the positive cap lead is installed in the positive battery terminal. The diode at D17 (1N4148) is removed, and a 100ohm resistor (or similar value) replaces the diode. Adding a resistor in place of D17 allows the game to charge the capacitor. Once the capacitor is installed, and the board installed back in the game, leave the game powered on to allow the game to charge the capacitor fully. After that, turning the game on monthly for about 10 minutes allows the capacitor to recharge. If the cap is losing its charge rapidly, diode D18 may be faulty, and should be replaced.
 

====System 7====
Follow these steps to add a SuperCap to a System 7 MPU.
#Drill a 1/16" hole NorthWest of the upper right positive battery terminal solder pad. The distance from the positive battery terminal hole should be the width of the SuperCap leads. The hole will be pierce a large ground trace on the solder side of the board (right hand image).
#Solder the SuperCap positive lead through the battery terminal solder pad.
#Solder the SuperCap negative lead to the ground trace on the solder side of the board.
#Remove diode D17, a 1N4148.
#Install a 100ohm (or thereabouts) 1/4W resistor in place of D17. Polarity is not important as resistors have no polarity.

The following images demonstrate the procedure.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Williams System 7 MPU SuperCap Installation">
File:WMSSystem7SuperCap-1.jpg|<center>1/16" hole drilled for the negative "leg" of the SuperCap.</center>
File:WMSSystem7SuperCap-2.jpg|<center>The SuperCap and 100ohm resistor installed.</center>
File:WMSSystem7SuperCap-3.jpg|<center>The solder side of the board showing SuperCap connections.</center>
</gallery>
</center>
 

===Installing NVRAM ===

NVRAM (non-volatile RAM) can be used in all Williams System 3 through 7 MPUs. By installing NVRAM, batteries will never, ever, be required to retain game settings and high scores. The possibility of spewing alkaline onto the board is eliminated.

For System 3-7 games, the 5101 RAM chip is always at IC19, although the actual physical position of IC19 on the MPU differs between the systems. Unfortunately, the 5101 RAM is '''always''' soldered directly onto the board. It must be desoldered and replaced with a 22-pin 0.3" width socket to accommodate the NVRAM.

NVRAM are discussed [http://www.pinwiki.com/wiki/index.php?title=MPU_Battery_Replacement_Options#Products here].

==Improving the Early System 3 Flipper Response==

For the early solid state games, Williams re-used the flipper mechanism from their electromechanical games. This design, composed of multiple pieces screwed to the bottom of the playfield, is functional but somewhat clunky in operation. There are those that advocate scrapping the mechanism and replacing it with modern Williams baseplate design flippers. While this certainly works, and provides a much nicer flipper response, it also costs money for new parts when the old parts can be made to work reasonably well.

First, rebuild the flipper assembly with fresh parts. This includes the coil stops, plunger and links, coil sleeves, EOS switches, cabinet switches, and pawls (if needed). Pinball Resource has all these parts.

This leaves a functional, reasonably strong, but 'clunky' flipper. It will work, but it will not seem as 'snappy' and 'fast' as a modern game. While the modern (WPC) baseplate style flipper mechanism is nice, the most important change is actually not the baseplate, it is the modern flipper bat itself.

There is a slight difference in mass between the original bat at 1.5 oz and the new bat at a little under 1 oz, but what accounts for the difference is the way the mass is distributed. On the old flipper design, a heavy metal base is welded to the shaft, and the plastic bat is screwed to the base. On the new design, the plastic bat is simply molded to the shaft, eliminating the base entirely.

<center>
<gallery widths=300px heights=300px perrow=2 caption="Williams Flipper Bat Comparison">
File:s3fbat1.jpg|<center>Williams System 3 flipper bat assembly (two-piece)</center>
File:s3fbat4.jpg|<center>Williams molded flipper bat assembly</center>
</gallery>
</center>

When the flipper coil is energized, it begins accelerating the plunger, pulling it in to the centre of the coil. This acceleration is transmitted to the shaft via the crank, accelerating the flipper bat. In this rotational acceleration of the bat, the further the mass is from the centre of the shaft, the more work required to accelerate it, and the slower the rate of acceleration. (Incidentally, this is why magnesium wheels first became popular in drag racing; they are lighter than steel wheels and increase the car's rate of acceleration. It does not change the car's top speed, but it does reduce the time it takes the car to reach top speed, making it quicker.)

At the end of the coil's power stroke, the plunger slams in to the coil stop, rapidly decelerating. In turn, then, the link, crank, and flipper bat also slam in to the previous part and rapidly decelerate. In this part of the action, the higher mass of the old flipper bat has more momentum, and due to the location of that mass, has more leverage to apply the force of the momentum. This leads to a hard clunk as all of that mass slams to a stop, and often results in a flipper bat that 'bounces' at the end of stroke.

The solution to both of these is to reduce the mass of the flipper bat, especially reducing it as far from the centre line of the flipper shaft as possible. Looking at the options, there are only three pieces to the flipper bat. The plastic bat is not really easily modified to reduce any serious mass. The screw that holds the plastic bat to the base is not easy to reduce in mass, and being located close to the centre line of the flipper shaft, it has very little effect on the operation. That leaves the flipper shaft and its welded on base.

The shaft itself has significant mass, but the mass of the shaft is located very close to the centre line, so it can be ignored as well. That, then, leaves the base. Here there is quite a lot of mass, and much of it is located a good distance from the centre line of the flipper shaft.

First remove the plastic shoe from the bat (there is a single screw underneath the bat). Then screw the metal bat to a piece of scrap wood, and drill the metal bat baseplate to remove metal. This is easiest to do neatly with a drill press. Drill two 5/16" hole near the shaft, and progressively smaller holes toward the tip. A total of seven holes can be drilled: 5/16", 5/16", 1/4", 7/32", 3/16", 5/32", 1/8". These holes remove about 1/2 oz from the flipper bat assembly without significantly affecting its strength or durability.

<center>
<gallery widths=300px heights=300px perrow=2 caption="System 3 Flipper Bat Modification">
File:s3fbat2.jpg|<center>Drilling the flipper bat shoe</center>
File:s3fbat3.jpg|<center>Flipper bat shoe after being drilled</center>
</gallery>
</center>

Reassemble the flipper bat, install, and enjoy. The flippers should feel snappier.

=Problems and Fixes=

== Cross Connecting Black and White Backbox Connectors ==
[[File:WMSSystem7PharoahConnectors.jpg|300px|thumb|left|The infamous System 7/9 connectors that can be cross connected. Yikes!]]
[[File:FirePowerCrossConnect.jpg ‎|300px|thumb|right|These two FirePower connectors are clearly misconnected as can be seen by different wire colors entering and leaving the connector pair. The connector colors should not be trusted. Image courtesy of Kevin Scholbe.]] 
In one of the biggest mistakes in pinball manufacturing, Williams used two identical 24 pin .062 connectors to connect cabinet and backbox wiring. The connectors are identical with the exception that one is black and one is white. During manufacturing, the wrong color connector was sometimes used. Bottom line: do not simply mate black to black and white to white. Instead, ensure that the wire colors going into one side of the connector are the same as the wire colors coming out the other side. This is the only foolproof method of avoiding the catastrophe of cross connecting circuits, causing certain damage to the MPU and/or driver board.
 

==Advanced Diagnostic Tool by Pincoder==

An advanced diagnostic tool with full (downloadable) documentation and active support is available here: [https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/ Pincoder Adapter]. The Adapter simply plugs into the MPU board right out of the box and can be used in-game for all tests.

==Built In Diagnostics==
[[File:WMSSystem3DiagnosticButtonCropped.jpg|300px|thumb|left|Diagnostic switch location on a WMS System 3 MPU]]The built in diagnostics of the Williams System 3 - 7 board set are extremely limited. The board set either powers up or it doesn't.

There are two diagnostic LEDs on the MPU (system 7 MPUs feature a 7 segment display). However, the usefulness of these LEDs is at best limited and generally just confusing. A properly booting System 3-6 game will flash both LEDs once, and then the LEDs will remain off. This flash is a bit longer than a flicker, staying on for about 1/2 second. A properly booting System 7 game will flash a zero on the 7 segment display. The 7 segment display will then go blank.

Pressing the Diagnostic button on a properly functioning System 3 - 6 MPU will cause both LEDs to flash twice in unison and then go off. If the bottom LED remains on, the game software is indicating a ROM failure. If the top LED remains on, the game software is indicating a RAM failure (6810). And if both LEDs remain on, the game software is indicating a CMOS RAM failure (5101). However, the accuracy of this test is questionable since the game software must be functioning properly for the test report to be valid and the game software requires ROM and RAM to function in the first place. The short advice is: don't rely on this diagnostic test result.
 

Pressing the Diagnostic button on a properly functioning System 7 MPU will cause the 7 segment display to flash a zero and then go blank. System 7 diagnostics are a bit more useful than prior Williams game systems but are still not 100% trustworthy. If the MPU built-in-test software detects a problem with the game hardware, the 7 segment display will remain on with an error code displayed. Possible error codes are:

*0 - and then goes out...all tests passed
*1 - IC13 RAM or IC20 ROM failed
*2 - IC16 RAM failure
*3 - IC17 ROM failure
*4 - IC17 ROM failure (duplicated test...yes)
*5 - IC20 ROM failure or the coin door was closed or memory protect fault
*6 - IC14 Game ROM failure
*7 - IC26 Game ROM failure
*8 - IC19 (5101) RAM failure or the coin door was closed or memory protect fault
*9 - IC19 (5101 again) RAM failure or the coin door was closed or memory protect fault

'''To test displays, lamps, coils and switches for System 3 and 4 games, follow this procedure first, then proceed to the System 6-7 procedure below .''' 

Entering the familiar diagnostic mode of later game systems is a bit less intuitive with a System 3 or 4 game. To enter diagnostics, press the diagnostic button on the MPU once. This is the lower of the two buttons as pictured at left. Both LEDs should flash and all displays will go blank. At this point, the game is ready to accept new game settings like "balls per play" via the obtuse and ridiculous to use dip switches on the MPU. Skipping over the process that essentially amounts to "memory pokes" (who remembers that), the diagnostics can now be controlled from the front door switches. If the AUTO/MANUAL switch is in the MANUAL position, pressing the ADVANCE button will cause each score display to show all zeros. The next press will show all ones, etc. If the AUTO/MANUAL switch is in the AUTO position, pressing the ADVANCE button will cause the score displays to begin cycling, starting with all zeros, then all ones, etc.

[[File:YT.png]] A video demonstrating System 3 and 4 game diagnostic entry can be found [https://youtu.be/Bq7Bubb5X6w here].

[[File:WMSSystem3-7CoinDoorSwitches.jpg|300px|thumb|left|Williams System 3 - 7 Coin Door Switches]]
'''For System 6-7 games, follow this procedure to test displays, lamps, coils and switches.''' 

With the AUTO/MANUAL switch in the MANUAL position, press the ADVANCE button. This will cause each score display to show all zeros. Pressing the ADVANCE button again will display all ones, etc. If the AUTO/MANUAL switch is moved to the AUTO position, the score displays will advance automatically through each of the digits (zero through 9).

With the AUTO/MANUAL switch still in the AUTO position, press the ADVANCE button to advance to the next test. The match portion of the credit/match display will show "01" and all playfield lamps will begin to cycle on/off.

Pressing ADVANCE again will display "02" in the match window, and the game will begin an ordered activation of each coil in sequence (including buzzers, flashers, etc).

Pressing ADVANCE again will display "03" in the match window. This is "switch test" mode. If no switches are closed, the credit half of the credit/match window will be blank. Closing a switch will result in the switch number being displayed in the credit window. If more than one switch is closed when switch test begins, the number of each switch will be displayed once in the credit window. After that point, only closing a switch will cause it's number to be displayed. i.e. switch test does not cycle through all closed switches but instead displays ONLY the last switch closure detected (at least in System 3 games).

Pressing the ADVANCE button one more time displays "04" in the match window, and game status information is displayed in sequence, automatically for system 3 and 4 games and by pressing the advance button for system 6 and 7 games.
 

== Quick Start: Repairing a Williams System 3-7 MPU ==

The procedure for repairing a Williams MPU is outlined below. More detail can be found later in this document.

<ol>
<li>Replace the power header at 1J2, which is located on the left side of the MPU. The cornerstone of a well running MPU is clean, consistent power. Tarnished connections, worn connections that have exceeded the mate cycle spec, and cracked header pin solder joints all negatively impact power.</li>
<li>If the OEM chip sockets are still on the board, replace them with quality twin leaf or machine pin sockets. Good chip sockets will ensure rock solid connections between the ICs and the various busses. Always replace Scanbe and white Molex sockets - no exceptions!</li>

[[File:OEMROMs.jpg|300px|thumb|right|The ROM on the right in this picture has obviously been heat stressed.]]

<li>Examine the 40-pin male connector closely. If it exhibits any of the following characteristics, replace it.
*Tarnished pins
*Corroded pins (due to batteries on the MPU leaking corrosive alkaline)
*Fractured solder joints
*Solder joint “craters”, i.e. an attempt to “reflow” the solder joint that doesn’t adhere to the pin very well. The solder surrounds the pins, but does not create a solid electrical connection to the pins.
</li>

<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>
<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>
<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect.</li>
<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>
<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>
<li>Make certain the blanking signal goes high and remains high almost immediately after successful MPU boot. The blanking signal is easily tested at pin 37 of the 40-pin interconnect board.</li>
<li>Install Leon’s test ROM to verify processor, PIA, and memory operation.</li>
</ol>

===Further Recommended Reliability Improvements===

#Replace all headers. Reflowing solder does not create a solid mechanical or electrical connection.
#Replace masked ROMs with new ROMs.
#Update the MPU to use fewer sockets. i.e. use a 2716 (or double the image into a 2732) at IC14.
#Move the backup battery to a remote location or install NVRAM. Batteries should be removed from the MPU board as soon as possible.

===Adding System 3-6-like Diagnostic LEDs to a System 7 MPU===
[[File:System7DiagnosticLEDAddition.jpg|300px|thumb|left|Diagram depicting addition of 2 LEDs and 2 resistors that provide the same function as System 3-6 MPU boards]]
[[File:System7FactoryLEDs.jpg|300px|thumb|right|A System 7 MPU with factory installed diagnostic LEDs]] 
System 7 MPUs replaced the two diagnostic LEDs of past systems with a 7-Segment LED display to provide diagnostic indications. At times, the 7447 driver IC or the 7-segment LED display itself can fail. Or perhaps running system 3-6 software in the board, while retaining the LED diagnostic capability, is the objective.

Rather than replacing the 7-Segment display or 7447, adding System 3-7-like LEDs to the MPU is easy. Procure 2 standard LEDs and two 1/4 watt resistors of any value between 100 ohms and 560 ohms. Incrementally higher ohm resistors will dim the LEDs incrementally, but can still be used.

Add two resistors on the right-most pads as pictured at left. 
Add two LEDs to the top two available pads as pictured at left, with the "flat side" (the short leg or anode) oriented toward the 7-segment display. It's as easy as that.
 

==Quick Start: Repairing a Williams System 3-7 Driver Board==

The detailed procedures for repairing a Williams driver board can be found later in this document.

<ol>
<li>Replace the 40-pin female interconnect. Due to fatigue and/or battery damage (alkaline corrosion), this connector can and will become unreliable over time. Replace it.</li>
<li>Remove and reflow the solder on *all* of the header pin connectors. Another choice is to replace the connectors with new ones.</li>
<li>Replace all suspect chip sockets. PIAs on the driver board were the only chips socketed from the factory on this board. However, the factory used crappy Scanbe sockets for these chips. If Scanbe sockets are present, replace them.</li>
<li>Inspect the PIA chips. If AMI chips were used, suspect eventual, premature failure. Replace if possible.</li>
<li>If the factory 3 watt current limiting resistors in the lamp matrix appear heat damaged, replace them with 27 ohm 5 watt resistors. "Sand" resistors are a good replacement choice.</li>
<li>If heavy heat damage is present in the vicinity of the lamp matrix power resistors, suspect potential failure of the lamp matrix ICs (IC13 & IC14) located just above the resistors.</li>
</ol>

==Using a PC Power Supply For Bench Testing==
Sometimes it is more beneficial to do testing / troubleshooting while the MPU and / or driver boards are outside of the game. It's unfortunate, but the System 3-7 boards were designed in such a way that both the MPU and driver board have to be attached to one another for the MPU to effectively boot and function. Since the driver board has no intelligence located on it, it needs to be connected to the MPU to be of any use. 

[[File:WMS Sys6 On Bench.JPG|300px|thumb|left|WMS System 6 MPU and Driver Board Powered by a PC Power Supply. Power connections are attached to the readily available test points on the MPU board.]]
[[File:WMS Sys7 Bench Power.JPG|300px|thumb|right|WMS System 7 MPU and Driver Board Powered by a PC Power Supply. Power connections are attached to IJ2 on the MPU board.]]
The voltages needed to power a System 3-7 board pair on the bench are +5v, +12v, and ground. Connections can be made to the appropriate pins on 1J2 (only header connection on left side of MPU board). The connections are as follows:

*Pins 1-3 (ground)
*Pins 4- 6 (+5 volts)
*Pin 9 (+12 volts)

If connecting a '''System 6 or 7 board pair''', it is easier to connect to the test points. The connections are as follows:

*Test point 1 (+12 volts)
*Test point 9 (+5 volts)
*Test point 10 (ground)

Note that test points 9 and 10 have different locations between a System 6 and 7 MPU board.
 

== Connecting a Logic Probe to the Williams System 3-7 MPU ==

[[File:WMSSystem3LogicProbeConnection.jpg|300px|thumb|left|Connecting a logic probe to a System 3-7 MPU. This picture is a System 3 MPU.]]
[[File:WMSSystem6LogicProbeConnection.jpg|300px|thumb|right|An alternate method to connect a logic probe on a System 6/6A MPU.]] 
The easiest way to power the logic probe is across the input power's electrolytic filter cap, as shown on this Williams System 3 board at left.
All MPUs, including Systems 3, 4, 6, 6A, and 7, feature this cap.

Since the MPU and driver board logic are electrically connected and powered by the same source, connecting the probe to the MPU allows probing driver board logic also.
 

==Connectors, connectors, connectors==

[[File:Wms cracked solder joints.JPG|thumb|left|300px|Cracked solder joints on the header pins of a Williams driver board]] 
With this era of game, most of them 30+ years old now, and they will have problems with connectors. One of the most common issues is cracked solder joints on header pin connections to the PCBs. Some cracks are more obvious than others, while some can only be seen clearly under proper magnification.
 

[[File:Wms header solder removed.JPG|thumb|left|300px|Solder removed from the header pins of a Williams driver board]] 
Although it can be somewhat time consuming and a tedious chore, it is best to remove the old solder from a header pin joint, and then add new, fresh solder. Performing this procedure is a necessity on these games to ensure reliability. The other option is removing the header pin connection completely, and replace with a new one.
 

If the game starts to reset for no reason during play, or when both flippers are engaged, it may be worth first re-pinning the connectors at 1J2 on the MPU Board and at the outputs from the PSU. This is always a good step even if it does not fix the immediate issue, as it avoids power problems later on. 

This will involves replacing the header pins on the PSU board and the female connectors on the cables. The pins are .156" and square pins are preferred, although round are still available. Use phosphor bronze. On the female side, crimp pins of the trifuricon type are best.

Second prize goes to reflowing solder to the back of the header pins, and just replacing the female IDC connectors with new ones. In that case rather than a crimper, the .156" 'punch-down' tool '''''must''''' be used for this replacement to work correctly. If the correct tool is not used, the IDC housing and pins will be damaged, especially if a screwdriver or some other makeshift tool is used. After that, the wires just don't seat correctly and will not maintain proper contact. Always cut back to clean wire and punch down correctly to a new IDC connector, reusing an old one rarely works.

Again, the connector is a .156" 9-way connector at 1J2. There is also a 'key' pin where the hole is blanked off on the connectors and the pin cut off flush with the board. This prevents plugging the power in to say the switch matrix or swapping two connectors over. It's easiest to just buy a bag of these for blanking off the 'key' positions, rather than try to re-use old ones.

==Wiring Connector Issues==
[[File:WMSSystem7BlownICs.jpg|300px|thumb|left|Socketed and replaced ICs blown by incorrect connector hookup.]] 
Williams made a poor wiring harness design decision with this series of games that allows the cabinet harness to be connected to the head harness (36 pin inline connectors). Mating these connectors incorrectly will short the 28V solenoid circuit to the logic voltage level circuit, destroying ICs on the MPU and perhaps the driver board. Always be sure to double check connector pin counts and colors, but most importantly, wire colors going into and out of both sides of the connector. Connector color is not a 100% reliable indicator as Williams sometimes used white connectors, sometimes used black connectors for both, and sometimes may even have used one black and one white connector. Wire colors should always match up.

A real world example on a System 7 Jungle Lord, pictured at left, resulted in MPU IC7 (7404), IC32 (7400), and IC12 (7408) being blown. The 5101 wasn't destroyed. On the driver board, IC16 (7406) was also damaged. The amount of damage can vary, however, other instances suggest a similar path of destruction. The best course of action should this occur is to spend a lot of time with a DMM in diode test, checking each individual IC. Socketed ICs, like the 5101 and the 6808/2 can be easily tested in a known working system.

 

==System 7 MPU Board Issues ==
Diagnostics, and the 'System 7 MPU Board won't boot'.

Forget about getting anything at all on the Player Displays without having working ROMs in place and a good MPU board. Blanking has to go 'high' before the displays will work. So coin door game diagnostics are useless until the MPU board runs correctly.

But help is at hand on the System 7 MPU, Williams added a single 7 segment LED display to the board. To get anything at all on the 7 segment display LED on the MPU, these conditions must be met:
* The 74LS47 Display Driver IC34 to be working.
* The 6821 PIA (at IC18) on the MPU responsible for driving the score displays to be working.
* The logic +5v to be good.

Normally when a properly functioning board boots, the 7 segment LED display will flash "0" briefly and then the display is turned off, and remains off. If within a game, the game would then be in attract mode if everything was perfect. Pressing diagnostics should show a "0" and then return to attract mode with the LED display blank. [ed Note: Correct me if that is wrong]

Once the above-mentioned chips are installed and working and the sockets have been replaced or tested good:
* With no ROMs installed, a board with a fault or a ROM fault if they are installed, the "top two" LEDs (if there) would be lit and the LED display would show "0". The MPU board is 'locked up', in that condition.
* Display Driver PIA IC PA4 - PA7 will be high. Pressing the * Diagnostic switch will not change things.

Then an OS is needed, which is the 'Flipper ROMs' in pinball.
When they 'Boot' (provide a set of instructions to the CPU)- even with the Game ROM removed, the fist thing they do is to "turn off" the LEDs 1+2 and so the onboard LED display (7447) would then go blank.

In fact, "0" should flash once and go blank. That means the board is not locked and at least booted the OS.

Installing a good Game ROM after that may provide access to the diagnostics if everything is working up to this point. Pressing the diagnostic switch should then provide a (hopefully) valid indication of what component is stopping the (pinball or whatever) from running. Here are the key indications (for System 7, Sys 8&9 may be similar):

These results can appear with error conditions by using the Flipper and Game ROMs, or the 2532 WMS Test ROM in IC17 (on Sys 7 boards):
If all the support chips are good, and one "0" flash appears and then goes blank, then the on-board error display can be trusted.

: '''Press the diagnostic button, the numbers are:'''
{| class="wikitable"
!colspan="2" |System 7 LED Diagnostics
|-
!Number
!Meaning
|-
|0 || Test Passed (only if display goes blank)
|-
|1 || IC13 RAM Faulty
|-
|2 || IC16 RAM Faulty
|-
|3 || IC17 ROM 2 Faulty
|-
|4 || IC17 ROM 2 Faulty
|-
|5 || IC20 ROM I Faulty
|-
|6 || IC14 Game ROM 1 Faulty
|-
|7 || IC26 Game ROM 0 Faulty
|-
|8 || IC19 CMOS RAM or memory protect circuit faulty
|-
|9 || Coin-door closed, memory protect circuit faulty, or IC19 CMOS RAM Faulty.
|}

Getting a 0 and remaining on could potentially be that the CPU / board has not successfully reset. In other words, no instructions have been passed to and from the CPU chip. This problem could be due to a faulty reset circuit. The lack of +12v on the MPU board can cause this too. 

Getting an 8 or 9 is *good* indication - it means the board is almost there!

Here are some further tips about those conditions:

8 - MPU board may be good. Is it looking for the Driver Board? (Like the missing 7th flash on a Bally MPU).

Make sure the Driver Board is connected and the "40-way" interconnect has continuity on all pins.
From System 8 on there is no interconnect... so by System 9 MPU and Driverboard (and Sound!) are all one PCB.

Then suspect that IC19 RAM is faulty or finally a memory protect fault.

9 - First check for coin door closed (or pin 1J4-1 or 1J3-1 is being grounded), then is IC7 faulty? Finally is IC19 RAM faulty?

If a "9" is displayed, it may be tempting to install it in a game, open the coin door, and try and boot up. But this is wrong, as there still is a problem on the board. Either the IC19 5101 CMOS Ram is faulty, or another memory protect component is faulty.

Remember to do the "switch on, off and back on again quick" trick to see attract mode appears when reinstalling in a game after taking an MPU out. Many times, that does the trick. Also, if removing the Driver Board and reinserting it on the MPU board 'fixes' the problems and the boards will then boot correctly, then it points to the "40-way" connector needing to be replaced. Both header pins on the MPU and sockets on the Driver Board.

Parts: 

The 7-Segment display can be replaced with a KINGBRIGHT SA03-12HDB LED 0.3" RED DISPLAY. 
5101 CMOS RAM. 5101-1 The low power version is needed, as it needs battery backup to hold RAM contents when the game is powered off. 
A 6821 PIA is a standard part. MC6821 MC68B21 are common. The 6820 designation is much earlier but also works. Other designations:

xx6821, xx68A21, xx68B21, where xx can be MC (Motorola) or HD (Hitachi Data) will all work. The 'A' in 68A21 means the PIA will run at up to a 1.5Mhz Clock , the 'B' in 68B21 means up to a 2Mhz clock, without any letter is up to 1MHz. Any final letter is Package type (P,S or L) P=Plastic S=Cerdip and L=Ceramic. Any of the above speeds or package types will work for this era of pinball, so the letters can be ignored and any 6820 or 6821 can be used.

==Chip Sockets==
Reliable socket connections are a requirement for any printed circuit board to work as designed. Old sockets, as discussed below, should be replaced. Use extreme care in desoldering the old sockets, the traces and pads on circuit boards are easily lifted, especially if any battery corrosion is in the area. 

The chip sockets on old Williams boards (also most any board of this era) are long past their reliable lifetimes. They may work, but they may also cause intermittent connections that will have you chasing your tail tracking down odd problems with the game. Like the 40-pin interconnect used in Williams System 3-7 games, these sockets should always be replaced. 

Perhaps the most maligned socket brand, and rightfully so, is the Scanbe brand. In the picture below, it can be seen why. These 30+ year old sockets passed the point of reliability many years ago. Included in the Scanbe socket picture below are two pins pulled from a Scanbe socket. The pins were designed to grip the SIDES of the IC legs, unlike the design of modern sockets that grip the front and back faces of the IC leg. Get rid of them now. 

Later, WMS switched to sockets made by Augat or Raychem (all Tyco now). They occasionally go bad, but they can usually be left alone. But there is another type made by Molex which should also be replaced if it is found on a PCB. When looking at the picture below, it can be seen why. Curvy isn't it? And the contacts break easily too. Not as bad as the Scanbe but not much better either.
 

<center>
<gallery widths=200px heights=200px perrow=5 caption="Poor quality and old sockets found on many early pinball machine circuit boards">
File:WMS Speech Scanbe Socket.JPG|<center>It's hard to believe that these sockets ever worked.</center>
File:WMS Scanbe Removal.JPG|<center>A Scanbe socket being removed from circuit board by gently prying it up.</center>
File:ScanbeSocket.jpg|<center>Closeup of the infamous "Scanbe" brand socket. "Scanbe" is molded into the top of the socket face.</center>
File:ScanBeSocketPins.jpg ‎|<center>Closeup of "Scanbe" socket pins. Surface contact area was small from the factory.</center>
File:WMSMolexSocket.jpg|<center>Another bad socket type usually found in system 7 pcbs. This one was made by Molex.</center>
</gallery>
</center>
 

==Voltages==
The MPU board needs two voltages to boot: +12v which only the MPU uses for the reset circuit, and +5v (logic power) for the MPU and Driverboard IC chips.

If the game goes dead, but the sound board continues to work then there may be a fault with the PSU, power connections to the MPU, blanking or the reset circuit.

Check for sounds by pressing the sound board diagnostic test. The game will need to bed switched off & back on to cancel the looping sound test. The sound board has its own PSU. It takes 18v AC directly from the transformer and makes +12v (reset) +5v ( logic) and also -12v (Speech and mixers). It's probably OK to assume the +5v and +12v going to the MPU (and Driver Board) are OK from the PSU if the sound board boots and runs. It's like a mini MPU, with the same CPU and one PIA chip.

The main PSU board only needs to make the first two, +12v and +5v (no -12v) for the MPU and Driver board. But it also generates DC power for the flippers and the solenoids (+28v DC or so).

==Power Supply Issues==
The key thing to remember is that the PSU board is made up of separate output circuits combined on one board. They don't interact, and are in order:
* +18v for Lamps,
* +28v Solenoids (and Flippers),
* Regulated +5v for logic B+ and an unregulated +12v for CPU reset,
* +/- 100v HV supply for the Displays.

We're not counting the G.I. (General Illumination) circuit as it is AC only and is fused on the fuse card below the PSU. It only passes through the PSU board to be fused and controlled with a relay starting from System 7 games.

Input AC power gets to the PSU board directly from the transformer for the +5v/+12v and the display voltages.
However, in the case of the Lamp and Solenoid voltages AC is 'full wave' rectified (to DC) ''before reaching the PSU board''. This is done using two Bridge Rectifiers BR1 for Lamps (to the Right of the backbox) and BR2 for Solenoids and Flippers (to the Left of the backbox).

'''Lamp Voltage Supplies:'''
* The +18v DC Lamp voltage passes through a very large 'blue can' filter capacitor between the BR and the PSU board. This 'smooths out the 'bumps' (called AC ripple ) in the DC waveform.
** Because the MPU Controlled Lamps (for the inserts) are strobed by the Lamp Matrix, the resultant voltage to the bulbs is "averaged down" to about 6v DC.
*** Lamps are rated at 6.3v and 250mA for #44 Bulbs (so 1/4 Amp) or 150mA for #47 Bulbs (about 1/7 of an Amp).
*** Because they use less power, #47 bulbs will generate less heat.
*** Replace any shiny 'silvered' bulbs and any that say 0.3A as they burn way too hot and will ruin inserts and cause paint to flake on your backglass!
** '''Note:''' This has nothing to do with the G.I. (General Illumination circuit) which is fused on a fuse card and reaches to G.I. bulbs as about 6.3v AC.
*** As they (almost) always stay lit, the G.I. bulbs tend to last longer running on an AC voltage.
*** The AC is 'Tee-d' off to the cabinet, playfield and the insert board (for the backglass lighting).
*** Wire colors for G.I. (and must be measured as AC) are Yellow and Yellow/White.

'''Flipper and Solenoid Voltage Supplies:'''
* The +28v DC Solenoid voltage passes straight through to the PSU where it is fused before leaving on the way to the playfield.
** There are some additional components (a varistor and some filter capacitors) on the PSU board for the Solenoid/Flipper power.

'''Connectors on the PSU Board'''
* All AC voltages come into the PSU board in the large 12-way connector 3J1, while the black ground wires are on the 6-way 3J2.
**The fused '''''AC and DC''''' voltages exit on the larger of the 'D' shaped connectors, while the black Lamp and solenoid ground wires exit on the smaller of the 'D' connectors.

'''+5v Logic and +12v Unregulated Supplies:'''
*In the case of the +12v (and +5v a logic power), the AC comes into the PSU board at 3J1-10 11&12 directly from the transformer windings.
** You can measure about 10v AC in at the bottom of the diodes D7 and D8 with respect to the board's ground.
*** The total AC input is 18.6v, so each diode 'sees' 9.3v because the transformer winding 'center tap' at 3J1-12 is grounded.
*** D7 connects to 3J1-10, and D8 to 3J1-11 and you would trace connections from there back to the transformer.
*** If you measure AC across the bottom of these two diodes you should see the full 18.6v AC.
*** Do not worry if this AC value is higher without a load, it can (and will) vary with changes in line voltages.
*** Values over 20v AC are considered normal without a load. ''It's a 'schoolboy error' to chase the voltages of unregulated supplies trying to get them to be exact.'' This includes the AC input and +12v DC unregulated supply.
** The two large diodes at D7/D8 rectify the voltage to around +12v DC, again this is unregulated.
*** It is filtered by a large capacitor (12,000 uF or higher) to smooth out the AC ripple.
*** It is fused at 4A Slo-Blow, before exiting at 3J6-6 as the +12v DC for the reset circuit on the MPU Board.

* To generate the regulated +5v logic supply
** The +12v input is filtered more by capacitor C16 and then passed through X3 which is a +5v voltage regulator.
** This exits at 3J5-6 as exactly +5v for the Master Display Board ICs and at 3J6-7 to 3J6-10 for the other +5v supplies (MPU and Driver Boards).

''Please note that the Sound Board generates its own +12v and regulated +5v supplies for both Sound and Speech Boards. This is discussed in the [[Williams_System_3_-_7#Sound_.2F_Speech_Board_Issues | Sound & Speech Board Repair]] Section.''

===General Illumination Connection Design Flaws===
Starting with System 7 games, the general illumination passed through the power supply. This was done to turn the general illumination off (for effect) via a newly added relay on the power supply board. Unfortunately, Williams did not spec connections which could properly handle the current used for the general illumination. The end result was connections, whether it be housings or header pins, which became hot and / or burnt. As the connections tarnish, resistance increases, and the connections become hotter. The cycle continues until an inline fuse blows, or in most cases, discontinuity in the circuit occurs.

The only option is to purchase the proper Molex housing and pins and replace both the male and female connections. Replacing one side but not the other is futile. The issue will reoccur at a much faster rate than replacing both sides. Another preventative measure is to reduce the amount of current draw by replacing the lamps with LEDs. LEDs draw less current than 44, 47, and 555 bulbs, and the GI connections become less of an issue in the future when LEDs are installed.

===+/-100v Display HV Section of PSU===
Here is a document for troubleshooting and repair of the Williams System 3-6 [[Media:PSU-Display-PWR.pdf|PSU Board Display Power]].

An attempt was made to create step by step tests so that reading a schematic is not required. Includes replacement parts for the HV section repairs.

If the 1/4A (0.25A) fuse at F1 always blows on power up, you may have a shorted UDN IC chip on the Master Display Driver board.
See this section on [[Williams_System_3_-_7#Master_Display_Drivers_for_System_3_to_6 |Sys 3-6 Master Display Drivers]] for testing all the UDN chips on the display board. You can use these tests for both UDN7180 and UDN6118 (or UDN6184) IC's.

Try removing the master display power connectors. If that stops the F1 fuse from blowing, suspect the Master Display Driver needs repairs before you rebuild the HV section of the PSU. Test the HV outputs of the PSU without any displays connected and see if the proper voltages are being generated from the PSU without a load. You need +5v logic, +100v and -100v supplies to run the Master Display board correctly. This will let you figure out if you need to rebuild the Master Display, the HV section on the PSU Board or both.

'''''From experience, if components on the PSU Board HV section are stressed, it is best to go ahead and rebuild the entire HV section replacing all components with new parts from a $10 kit. It will save you time!'''''

===PSU Parts Suppliers===
Check with: 
[http://www.greatplainselectronics.com/Category-29.asp Ed at GPE] has HV rebuild kits and most parts. 
[http://lockwhenlit.com/Products.aspx Rob Anthony's LockWhenLit] (Borygard from RGP) may also have some PSU parts. 
[http://www.bobramstad.com/pinball/sys6ps.html Bob's PSU parts list] shows the Mouser part numbers which is useful if you live in the USA, or just want to order a few items for your PSU repair.

Also check with your favorite electronics supplier. Please be aware that NTE replacement parts may have wide tolerances so they will be compatible with a greater number of original parts. So get the correct replacement parts wherever possible.

===PSU Diagrams and Resources===
'''Please refer to these files while using this section to diagnose and repair your PSU Board:'''

* [[Media:11-powerwiring-sys4-6.pdf|Williams System 3-6 Power Wiring Diagram]] showing the wiring from your AC mains plug right through to the connection to the PSU board, Sound Board and the G.I.

* [[Media:07-powerlogic-sys3-6.pdf|Williams 3-6 PSU Logic Diagram]]. A PSU Board Schematic for System 3-6 games, containing test points with approximate voltages and help with fault finding your game's power.

* Troubleshooting and repair of the Williams System 3-6 [[Media:PSU-Display-PWR.pdf|PSU Board HV Display Section]]

* External link to a PDF of [http://www.greatplainselectronics.com/Downloads/W3-11_HV_Kit.pdf WMS HV parts and instructions] from Ed at GPE, a great place to get your HV repair kits.

'''Other Resources to visit''' 
Except for the possible use of different transistors for Q1 and Q3 the later System 9-11 HV section is very similar in design. So it will be worth reading through the [[Williams_System_9_-_11#Display_problems |Sys 9-11 Master Display Driver Problems]], for more detail before starting your repair.

'''''Missing PSU Upgrade Sections to add'''''
* Testing the AC in and DC out for all sections, including the Solenoid and Lamp BRs. Simple to do, but should it be spelled out?
* How to fit the replacement transistors with the 'twisted legs' as the SDS-201 and SDS-202 are obsolete. Although a diagram is on the GPE PDF for Ed's HV kit, some shrink wrap tubing could be added to the 'lowest leg' to reduce failures.
* How to fit the 2 x 1n4763a 91v zenerDiodes, at locations Z2 & Z4 to reduce the Display out put to about+/-90v under load and extend display life.
* Repin of Headers at 3J1 and the used pins at 3J2, theory for using crimped trifuricon connectors and new housings which replace the existing female IDC connectors.
...etc.

==The MPU Reset Circuit==
The +12v for reset goes into a circuit that waits (for about a 1 sec. delay) for the +5v to stabilize before it lets the CPU boot. If the +12v (or output from the reset circuit) drops, the reset halts the CPU, PIA(s) and the 5101 CMOS RAM chips before the +5v to them dies. A shutdown of the CPU will also pull blanking low and halt solenoids, lamps and displays to protect them from further damage (coils firing, memory glitching) during the power down. So spikes or drops to the +12v line may halt the CPU at the wrong time.

An MPU unable to boot may mean that its reset circuit is faulty. A +12v line comes in from the PSU board to the MPU on pin 9 of 1J2. That's the top pin on the top left (and only connector on the left) of the MPU board. +12v can also be measured at TP1 on a System 6, 6a, or 7 MPU. Don’t get hung up on it being exactly +12v, as it's not regulated. However, it can’t drop too much lower than +11.5v, or the reset circuit '''may''' have a problem generating enough voltage to keep reset “up” to the CPU. But +11.5v to +14v is not unusual and will still work. A fluctuating reset can cause the game to reboot during a game.

The state of the reset (high or low) can be observed at pin 40 of the 6808 or 6802 CPU chip. Likewise, the reset can be observed at TP8 on System 6, 6a, and 7 MPU boards. TP8 is located just to the right of IC19 (5101 memory) on a System 6 or 6a board, and the far right test point on the bottom of the MPU just above the 40-way connector on a System 7 MPU board. It will be marked as TP8 on the PCB mask. For System 3, 4, 4a MPU boards, the reset will have to be measured at pin 40 of the 6800 CPU board. When booting the game and watching reset, it stays low for a heartbeat after power on and then rises to +5v. +4.75v or around that is fine. Don't get hung up too much on the voltages being exact for the reset circuit either.

If the +12v appears OK when measured, and the sound board is always booting and working, it's safe to assume that +12v at the PSU is stable.

A good trick to 'inject' a reset, is to try connecting +5v for a second or two to the reset test point at TP8 or the leg of the CPU chip (pin 40). If the CPU boots (reset must be a logic high now on pin 40 of IC1), then the reset section will need to be rebuilt..

So that involves running a jumper lead from TP8 and '''briefly''' touching TP9 (+5v). TP9 is located just to the bottom right of the battery holder on a System 6 or 6a MPU board, while it is at the top right the battery holder on a System 7 board. The battery holder should have been removed, so the test point is located in the vicinity of where the original holder '''used to be'''.

===Repairing the Reset Circuit 'Divide and Conquer'===
Assuming that the game boots and works if the CPU reset pin is held high, how can it be determined what is wrong? One solution is the shotgun method: just start changing transistors and components until it is fixed. However, this wastes time and parts. A better way is to narrow down the fault location using the 'injection' trick.

The reset circuit is easily seen as two halves. For a System 7 MPU board, +5v can be applied directly to the top of resistor R12. If the board boots and stays stable, then that indicates the problem is on the 'right hand' side of the circuit. (On System 6, the same thing can be done, but using R32. This method helps narrow down the faulty components by a half.)

Assuming that the +12v getting to MPU board is good, if the above injection of 5v doesn't work, measure where the voltage disappears on the left hand side of the reset circuit. Then replace parts on that side, checking for a good reset when the board boots each time. Remember that for System 6 and 7, there are just 12 active components that make up the reset circuit, and 8 of those are transistors. Those are usually the source of the problem.

===Step One===
The Right Hand Side.
Start by replacing transistors Q6 – Q9 (all 2n4401 NPN) get 10 or more of them, they’re cheap to buy and they are commonly used. They are used as pre-drivers for the solenoid power transistors on the driver boards for System 3-7).

Test the board for the previous booting problem. If they are still there, replace the two zener diodes: ZR1 is a 6.8v Zener (1n5996) and ZR2 is a 3.9v Zener (1n5990) - you can't replace these components with anything else to my knowledge. These are critical values. And put the orientation of the band of the diode the same way as the ones that are removed. Taking a photo of how the circuit in the top left of the board looked before making any changes is a good idea. Or, only replace components one at a time. A test boot could be done on the bench each time something is replaced, but that may slow things down. On the other hand, this may result in avoiding replacing more components than necessary.

It should be booting now, if not attack the other half.

===Step Two===
The Left Hand Side.
Start by replacing transistor Q2. Q2 is a 2n4403 PNP transistor, cheap as well but you won’t need as many for pinball repairs. then replace Q3-Q5 with the 2n4401 's like before. I would replace D19 (a 1n4148 fast switching diode) you could test it with the diode setting of your DMM, but I don't trust testing diodes in circuit, and if I’m soldering in that section, I just cut it out and replace it. Cost will be pennies, and most pinball people should have new ones on hand. Again, be sure and notice the direction of the band on the old diode, and put the new one back the same way. Same thing goes for the orientation of the flat side of the transistors. Don’t get them wrong when replacing. The last component to replace would be the capacitor at C27 (10 uF @10v is the original part –look on the side of the cap). Replace it with a tantalum 10 uF @ 16v, if you can find it. You can go up in voltage even to 20v or more, but don’t change the value of the capacitance. Note that some caps have markings showing a (-) side, usually running down the side of the capacitor. If it shows a polarity, the (-) side of C27 points down on the PCB, towards the 40-way interconnect.

===Step Three, Hopefully Reset is Back Up===
That’s it. Usually fixed at step one, and down to one (or more) of those transistors. I have seen a zener or the 1n4148 diode at D19 be the problem before. But for me, the cap C27 has always been good. If all else fails, test the capacitor for a dead short with the power off and replace it with a 10uF electrolytic if it is shorted to ground or you aren't sure it's working.

===An Alternative to Rebuilding the Reset Circuit (System 6 and 6a)===
[[File:WMS Sys6 Reset Stock.jpg|left|thumb|300px|Williams System 6 MPU board stock reset circuit]]
[[File:WMS Sys6 MPU Reset Gen.JPG|right|thumb|300px|Williams System 6a MPU board reset circuit with an MCP130-460GI/TO reset generator installed]] 
There is an alternative to the stock reset circuit on System 6 and 6a MPU boards. A reset generator can be installed. To do so, some components will need to be removed and two jumpers installed. The following work will have to be done.
 
#Remove the following transistors - Q4 and Q6
#Remove the following resistors - (from left to right as installed on the board) R43, R38, R39, R41, and R42
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP130-460GI/TO where Q4 was (green highlighted area in image). Orient the reset generator in the same manner Q4 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q4). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the top pad and bottom pad of where R39 was (yellow highlighted area in pic). Essentially, replace R39 with a zero ohm jumper.
#Add a jumper between the top pad of R42 and the "C" collector pad (top pad) where Q6 was installed (orange highlighted area in pic).
 

This a very simple, and in some cases, cheaper alternative to repairing the existing reset circuit. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 6 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from [http://www.greatplainselectronics.com/proddetail.asp?prod=MCP130-460GI%2FTO Great Plains Electronics].

[[File:WMS_Sys6_Reset_Gen-Pullup.jpg|right|thumb|300px|Williams System 6A MPU board reset circuit with an MCP120-460GI/TO reset generator installed with a pull-up resistor]] 
Alternately, an MCP120-460GI/TO reset generator can be used, except a 4.7K 1/4 watt pull-up resistor will have to be added to the reset signal line.

#Remove the following transistors - Q4 and Q6
#Remove the following resistors - (from left to right as installed on the board) R43, R38, R39, R41, and R42
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP120-460GI/TO where Q4 was. Orient the reset generator in the same manner Q4 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q4). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the bottom pad of where R38 and R39 formerly were.
#Add a 47k 1/4w resistor between the top pad of where R38 was and the bottom pad of where R41 was.
 

===An Alternative to Rebuilding the Reset Circuit (System 7)===
[[File:WMS Sys7 Reset Components Remove.JPG|left|thumb|300px|Components to remove from a Williams System 7 MPU board reset circuit]]
[[File:WMS Sys7 Reset New Components.JPG|right|thumb|300px|Williams System 7 MPU board reset circuit with a reset generator installed]] 
Like the System 6 and 6a MPU boards, a reset generator can be installed on a System 7 board. Some components will need to be removed, a single jumper installed, along with a 4.7k ohm resistor installed. 

Procedure
#Remove Q2 transistor
#Remove the following resistors - (from left to right as installed on the board) R27, R24, R31, R25, R29, and R30 (resistor located to the right of Q2)
#Remove zener diode ZR1. This will keep any of the existing components in the reset section from being powered by the unregulated 12 volts.
#Add reset generator MCP120-460GI/TO where Q2 was (this is the same reset generator as used on Data East MPUs). Orient the reset generator in the same manner Q2 was oriented (pin 1 of reset generator will install where the "E" emitter was for Q2). In other words, the "flat" side of the reset generator will face to the left.
#Add a jumper between the bottom pads where R27 and R24 formerly were.
#Add a 4.7K ohm 1/4 watt resistor in place of R25.

[[File:System7ResetSection.jpg ‎|left|thumb|300px|All components of the reset section have been scraped except those required to use the MCP120-460GI/TO reset generator (marked with gold Sharpie). In this picture, the 74125 stuffed at the factory has been removed as it's original function was to read the DIP switches. System 7 games do not read the DIP switches.]] 
This a very simple, and in some cases, cheaper alternative to repairing the existing reset circuit. After this modification is performed, the MPU will no longer need the +12VDC to successfully boot. The remaining components in the reset circuit can be removed if desired as pictured at left. The MCP120-460GI/TO reset generator can be purchased from [http://www.greatplainselectronics.com/proddetail.asp?prod=MCP120-460GI%2FTO Great Plains Electronics].

Note: if using the MCP130 variety of reset generators, the 4.7K ohm resistor does not need to be installed as they incorporate the resistor internally.
 

===Reset Circuit Summary===
Connectors were mentioned above for completeness. While I agree a good 40-way connector is essential for correct operation of this era of games, changing the Bridge Rectifiers in the backbox or rebuilding connectors probably won't help fix the reset circuit .

That because the '''BR's are only for the Lamps and Solenoids''' and won't fix a problem with the MPU power (or reset) as that is sourced directly from the PSU. The +5v logic power comes from a regulator on the PSU board, and the +5v for the reset pins of the MPU ICs is created on the MPU from the +12v unregulated supply.

If you are looking here because game resets (reboots to attract mode or locks up) when flipping the flippers, it makes sense to check and rebuild the solenoid power circuit as well. That is the flipper power on games prior to System 7 when 50v flippers and a Flipper Power Board was introduced. You should also read the [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#WPC_5VDC_Power_Derivation_Path WPC section], while the games only similar- the approach for resets caused by power fluctuations is sound. It takes you from the 'AC mains' wall plug right through to the power needed on the boards.

Topics such as electrolytic capacitors aging and drying out, testing the Bridge Rectifiers and checking and tweaking the LM323K 5V regulator on the Power Baord will all be the same or very similar.

==The Blanking Circuit==
The blanking circuit is used by the MPU to prevent damage to the game when the MPU can not determine that the game is in a valid state. A low blanking signal means that the MPU isn't operating properly and the blanking circuitry is "blanking" (turning off) the lamps and displays. A high blanking signal means that the MPU is operating normally, allowing lamps and displays to function normally.

On the driver board, the blanking signal is logically ANDed, by 7408s, with the enable signal for all 8 of the lamp strobes and the first 16 solenoids. The 6 special solenoid enable signals are not ANDed with the blanking signal. 

On the MPU, the blanking signal for the displays leaves the board via connector IJ3 pin 4 (top left connector on board). For the driver board blanking signal, it leaves the MPU board at pin 37 of the 40-pin interconnect.

A special note: the blanking signal will only go high when the MPU and driver board are connected. It will not go high if testing with a stand alone MPU board.

===Adding a Blanking Indication LED to the Driver Board===
[[File:WMSSystem3-7BlankingLED.jpg|thumb|400px|left|A "blanking" LED added to a Williams System 3-7 Driver Board.]] 
Adding an LED as shown in the image will let you easily monitor the Blanking state while troubleshooting. Note that the "flat side" of the LED faces away from the 40-way connector and is on the same side as the shorter lead. The “current limiting” 150 ohm resistor is soldered to the ground trace. 
 

===Adding a Blanking Indication LED to the System 6/6A MPU Board===
[[File:WMSSystem6MPUBlanking.jpg | thumb | right| 400px| A blanking signal indication can be added to a System 6 MPU quite easily.]] 
#Remove the TP4 test stud. This is the blanking stud.
#Install the "non flat side" of the LED into the open hole.
#The "flat side" of the LED is oriented up, or toward the top of the board.
#Solder a 150 ohm (or so) resistor between the flat side lead and ground trace that has a zero ohm resistor soldered to it.
#All done.
 

===Adding a Blanking Indication LED to the System 7 MPU Board===
A blanking signal indication can be added to a System 7 MPU can be done in at least two very clean ways. 
When the LED is lit, the blanking signal is high, indicating a properly functioning MPU. 

==== Option 1 ====

Implementing this modification assumes that the battery holder trace is no longer in use! 
Procedure
#Remove the Blanking test point stud (numbered "4"). Since we are adding a blanking indication LED, the stud is no longer required.
#Install an LED, with the flat side pointing toward the former location of the battery holder and the other leg through the hole created by removal of the blanking TP stud.
#Bend the LED lead through the former battery holder hole and solder.
#Form a 150 ohm 1/4W resistor between the appropriate battery holder hole and the fat ground trace along the perimeter of the board.
#Scrape the solder mask from the board, enabling the resistor to be soldered to the ground trace.
#Solder both ends of the resistor.
#Add a label to indicate the meaning of the LED; lit means blanking is on and the MPU is working properly; unlit means blanking is off and there is a problem with the MPU.
 
<center>
<gallery widths=480px heights=480px perrow=2 caption="Option 1: Adding a Blanking Signal Indication to a System 7 MPU">
File:WMSSystem7BlankingLEDFront.jpg|<center>An LED replaced the Blanking test point stud, flat side pointing toward the battery holder hole.</center>
File:WMSSystem7BlankingLEDBack.jpg|<center>The back of the System 7 MPU, showing connections of the LED, repurposed battery holder trace, and 150 ohm resistor connection.</center>
</gallery>
</center>
 

==== Option 2 ====
This method does not require the battery holder to be removed. 
Procedure
#Clean the original solder from the lower of the 4 "paired" solder pads and the "via" pictured below.
#Install an LED, with the flat side oriented as indicated by the silkscreen
#On the solder side of the board, connect a 150 ohm 1/4W resistor to the LED lead on the "flat side" of the LED.
#Solder the other end of the resistor to the large ground trace.
#Bend the "non flat side" lead of the LED so that it can pass through the via hole and solder securely. This connects the LED to the blanking signal.
#On the solder side of the board, sever the trace shown in the image below that runs NorthEast from the LED (trace severed at gold dot using a Dremel tool and ball cutter bit).
#Add a label to indicate the meaning of the LED; lit means blanking is on and the MPU is working properly; unlit means blanking is off and there is a problem with the MPU.
 
<center>
<gallery widths=480px heights=480px perrow=2 caption="Option 2: Adding a Blanking Signal Indication to a System 7 MPU">
File:S7BlankingFront.jpeg|<center>An LED added to available solder pads, flat side pointing in the same direction as indicated on the silkscreen.</center>
File:S7BlankingBack.jpeg|<center>The back of the System 7 MPU, showing connections between the LED, a 150 ohm resistor connected to ground, and the "non-flat-side" lead of the LED connected to the blanking signal.</center>
</gallery>
</center>
 

===Blanking Circuit Stuck Low===
The blanking circuitry that appears on Williams 3-7 MPU boards remained the same across all generations of Williams MPUs, all the way through the System 11 board set. Data East copied the same blanking circuitry too!

The blanking circuit explained

#A properly executing CPU will send data to the display 6821 PIA at IC18 at regular intervals.
#This action causes PA2 at pin 4 of the 6821 at IC18 to periodically pulse.
#The signal is inverted by the 7404 at IC7, in at pin 5, out at pin 6.
#The coupling capacitor at C32 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q5 and to pin 8 of the 556 timer at IC23.
#The 556 timer is configured as a "missing pulse detector" meaning that if it does not detect the pulse that originated upstream at the 6821 PIA at IC18, the output of the 556 timer at pin 9 (and 13) will go low, which invokes blanking and protection of the system circuitry.

Upon a successful boot of the MPU board, the blanking will go from a low signal to a high signal, and remain high (no pulsing) as long as there are no issues. If the blanking signal does not go high, the system has not and will not boot. 

One of the most common issues for a blanking signal to remain low is discontinuity between the MPU board and the driver board. The blanking signal passes via the 40-pin interconnect at pin 37 (4th pin in from the left side). Poor connections due to fatigue or seeping battery damage can cause a break in this connection. It is best to replace both the male and female sides of the 40-pin interconnect to ensure that all is well. Remember, the blanking will not go high, if the MPU is not connected to the driver board. A flaky connection with discontinuity between boards is the same as if they're not connected. 

[[File:WMS Sys6 MPU Ground IC5.JPG|left|thumb|300px|A System 6 MPU board with the upper right battery holder through-hole circled, along with the ground trace and the 74LS02 labeled.]] 
A special note about System 6 & 6A MPU boards. The upper right through-hole for the battery holder passes the ground from the solder side of the board to the IC5 (74LS02) chip. This through-hole can become compromised from battery corrosion or the careless removal of the battery holder. If there is a break between the two sides of the board, ground will not be connected to IC5, and the chip will not function. If this occurs, the blanking signal will never go high, and the board will not boot. Just check for continuity between pin7 of IC24, the top right leg of chip shown and TP10, the bottom post on the right of picture. You may have to add a ‘stitch wire’ soldered to the top & bottom of the board going through the hole indicated. 

[[File:WMS_Sys7_Blanking.JPG|left|thumb|300px|System 7 MPU board blanking signal trace]]
A special note about System 7 MPU boards. The trace for the blanking signal is very fragile. If the batteries have leaked on the board, or leached under the 40-pin header pins, make certain that the trace which carries the blanking signal has not been broken. The break most commonly occurs at the junction of the trace and the component side of the through-hole pad for the header pin on the MPU board. A continuity test can be performed to determine if the trace has been compromised. Place one lead of the ohmmeter on TP4 and the other on pin 37 of the 40-pin header. Also, keep the lead on TP4, and place the other on the 12th pad up on the far right of the board. The header pin connector will have to be removed to inspect this junction, should there be a break. 

===Blanking Circuit Strobing===
There is a peculiar instance where the blanking circuit will be strobing. The end result is erratic behavior from the displays and lamps (both the lamps and displays will be very dim if at all visible during attract mode). The prime source of this issue is due to the C31 capacitor (1.0uF 25v axial tantalum) falling out of spec.
 

==Driver Board Issues==

===The "Once Dreaded" 40-pin Connector===
The driver board mates with the MPU board using 40 x 0.156" extra long header pins on the MPU and female 'bottom entry' Molex sockets on the driver board. Common belief is that these connectors are good for about 25 reliable connects and removals. While there may be disagreement with this number, the fact remains that the connector is good for a limited number of uses before the connection degrades. At that time, the connector must be replaced. 

The connectors between System 3-7 MPU and driver boards were/are a continual source of problems for this era of Williams machines. However, the issue was eliminated with the release of System 8, (and the more common System 9 platform), when the MPU board and driver board were merged together into a single board. 

If the header pins on the MPU board aren't tarnished, burned, or previously sanded, you may be able to get away with re-flowing the solder on these pins following these steps.
* Heat up the pad, add a little new solder
* Remove all the solder you can (the old and new) with a solder sucker
* Add fresh solder back to get a nice flow around each pin

[[File:Wms drvr interconnect.JPG|left|thumb|300px|The 40 pin female connector on the driver board]]
Then, replace all the female connectors on the driver board. Even if the driver board side pins look good, replace them. Simple cleaning of the pins with a contact cleaner or burnishing them are not viable solutions. The bottom feed pins loose tensile strength over time, which degrades the connection between the MPU and driver board as they age. The picture at left illustrates the 40 pin female bottom feed connectors on the driver board. It should be noted that the connector in the picture is an extreme example of poor condition connections. Missing and alkaline damaged pins, connectors from position 17-40 on the left, are not the norm. Connections from position 1-16 on the far right are more commonly seen.
 

[[File:WMS Interconnect Back.JPG|left|thumb|300px|Installing a new 40 pin female connector on the driver board]]
[[File:WMS Interconnect Front Done.JPG|right|thumb|300px|A new 40 pin female connector installed on the driver board]]
If using four 10 pin female connectors, (the originals on the driver board were five 8 pin), here's a little trick to keep them lined up nicely when soldering them. Take the old 8 pin male header pin connectors, which were installed on the MPU board. Install three of the 8 pin headers on the back side of the driver board and into the new female connectors (see picture to the left). If any of the older header pin sections have battery corrosion on them, do not use use them for this. Allow enough space between the connectors so some of the female connector leads can be soldered. Solder all of the exposed leads on the female connector. Once they are soldered in place, remove the male headers, and solder the remaining leads on the female connectors.
 

[[File:Male40PinHeaders.jpg|right|thumb|300px|Fresh male headers installed on this System 6 MPU. Nice. Note the new headers are 10 pins long while the original headers were 8 pins long.]] 
Parts for the MPU are:
*Square .156" header pins. These can be found at Great Plains Electronics [https://www.greatplainselectronics.com/proddetail.asp?prod=2420-10-2260 here]. Alternatively, Molex brand longer pins, part number 26-48-1080, can be used. Both of these options meet the length requirement for the pins to be at least 0.629" or 16mm length.
Parts for the Driver board are:
*10-way 0.156" Bottom Entry Female Molex Part Number: 09-52-3102 (4 needed per board). The original part, 5A-9066 8-way .156" Female Molex Part Number: 09-52-3082 (5 needed per board). Alternates are Molex 09-62-6104 and 09-52-3102 which are hard to obtain. 

Check with:
[http://www.greatplainselectronics.com/Category-82.asp Ed at GPE] or your favorite supplier for these.
 

[[File:UsingFemaleHeadersToAlignMaleHeaders.jpg|left|thumb|300px|Female housings being used to align the male headers.]] 
A trick similar to the method aligning the female housings can be used to align the male headers. Use the old (or new one housings) to align the male headers as pictured at left.
 

There is no substitute for doing this correctly, other than buying reproduction boards. A solution is a board made by Rottendog Amusements, where the MPU and driver board are [http://www.rottendog.us/?product=mpu327 combined into one board]. Cost is anywhere from $350 - $400. Another option is purchasing both the [http://www.pinballpcb.com/System3-7MainBoard.html MPU] and [http://www.pinballpcb.com/System3-7DriverBoard.html driver board] from Kohout Enterprises for $425. When both boards are purchased, they can be tied together via an auxiliary ribbon cable. Of course they can be connected via the 40-pin interconnect too. 

If doing it yourself, repairs on the MPU and driver board connectors can cost up to $30 or less in parts (header pins, sockets and solder), along with several hours to replace the connectors and pins correctly. This of course depends on your level of soldering skills and the value you put on your time. It's a fairly long job but it's likely that it only needs to be done once.
 

==Display Issues==
===Every-Other Digit Shown On All Displays===
[[File:WilliamsSystem3-6EveryOtherDigitOut.jpg ‎|thumb|left|300px|Half of the digits, or every-other digit, are missing on all displays. Unintuitively, the root cause of this failure is the lamp matrix 6821 PIA at IC10 on the driver board.]] 
This failure seems to occur quite frequently and perplexes most techs. While the 6821 in the MPU display interface circuitry would seem to be the logical culprit, it is the lamp matrix PIA on the driver board that is the actual villain. The issue shown at left was remedied by replacing PIA III (also known as IC10), the lamp matrix drive PIA, which is the middle PIA on the driver board.

[[File:YT.png]] A YouTube video demonstrating this failure, and the correction, can be found [https://youtu.be/ckwoW_xuQSM here].
 

===Repairing the Master Display Driver===
Note that the detail here is for System 3 - 6a with 6-digit displays only. So it does not include Alien Poker or Algar, which both used the System 7 type display setup. System 7-9 used a smaller Master Display Board located on the back of the lamp board, and it had IDC type ribbon cables that ran to the 4 player 7-digit displays. They added a 4-digit Credit/Match display which also used a ribbon cable. The harness connecting the backbox (PSU and MPU) signals to the Master board used the same 'edge-connector' as System 3-6).

===First, a High Voltage '''***Warning***'''===
With the game on you are dealing with +100 and -100v HV DC (High Voltage) going to the displays. That's a potential 200v difference and you only need to feel that once to know it. Wear tennis shoes (trainers or any rubber soled shoe) when working on displays with the backbox open. This is a shock hazard! If you are not capable or happy with measuring these voltages with a steady hand, then get someone else to help you and be there to 'spot' you. Always a good idea and more fun than working on your own.

Another useful tip is to remove Fuse F1 from the PSU (Power Supply Board). This is the HV fuse and is 1/4A Slo-Blow (250mA 'T' fuse in Europe). This will allow the logic (BCD binary decoders and Buffer ICs) to be troubleshooted with a DMM or Logic Probe without the danger of shocks or shorting them out when measuring TTL (logic) voltages. It may also save the logic probe from a crispy fate.

===Master Display Wiring Harness===
Sometimes displays just go blank and it is a fault in the wiring harness from backbox to the Master Display Driver. If you can swap a working Master Display Driver board from a System 3-6a game with stable displays, then do that as a first step. This way you quickly determine if the fault is in the backbox '''OR''' the Master Display Driver PCB or displays on the front of the light board. If it's the towards the backbox then suspect display harness cabing Driver to MPU, or the display PIA or decoding on the MPU. If you don't have the ability to swap in a spare Master Display board, then turn off the game and test the harness for continuity between the backbox (MPU board) and the cables at the left and right side of the Master using this ''[[media:10-displaywiring-sys-4-6.pdf|Master Display board harness wiring diagram]]''.

===Segment failures===
Segment failures on a single display could be that display failing. Same issue if just one display is blank. Swap that display with another (power off first) and see if the problem moves with that display. If it moves, it's that display glass or its board. If it doesn't move and stays at the same player location, see below for the possible suspects.

Segment failures on multiple displays and probable cause:

Players 1 & 2 Segments and master display Segments are out:
* BCD inputs are A1 B1 C1 D1 from the MPU board
* MC14543 BCD to 7-Seg. Decoder IC5
* UDN7180 Display Driver IC9
* Resistors R1-R7

Players 3 & 4 Segments
* BCD inputs are A2 B2 C2 D2 from the MPU board
* MC14543 BCD to 7-Seg. Decoder IC8
* UDN7180 Display Driver IC10
* Resistors R8-R14

Start out by measuring all the resistors on the master display board with the power off.
R1-R14 should be around 10K ohms. Any that are not within about 10% (say a range between 9.6K to 10.4K ohms) need to be replaced. Also look and see if any look "toasted".

Those resistors get cooked on the Master display boards and usually will then cause single segments to fail on both the player 1&2 or 3&4 displays together, as they are linked. Te resistors need to be replaced with the same value: 10K but at 1/2 Watt. Some of the modern 'metal film' resistors are rated at 0.6W which is perfect and they fit nicely in that location. Older 0.5W (1/2W) resistors are larger, but are fine. Mount them slightly off the PCB so they get good airflow all around the resistor body.

Do the above steps anyway, no matter what the display problem is although it's probably not going to be the whole story.
Replacement resistors are cheap and will prolong the life of your displays. Reducing the voltage going to the displays when rebuilding the HV section of the PSU is a good step to take and will help as well. You only need to replace two Zener diodes to achieve this.

===Digit Failures===
Strobe inputs for the display digits come in to three 14069 hex inverters on the driver board. IC1, IC2 and IC3.
* IC1 is dedicated to the Master Display 'Credit/Match'. Strobes are: 15,16,7,8 left to right, for the 4 digits it uses.
* IC2 and IC3 strobe inputs are more complicated, to strobe distribution between these IC chips is shown in the display diagram below.

Strobe (or strobe input) failures are likely to show up in the player display pairings 1&3 or 2&4 because:
* Strobes 1-6 are shared for players 1 & 3
* Strobes 9-14 are shared for players 2 & 4

===All Displays are Blank===
This could be that the +100v or the -100v HV are missing from the PSU board. Both have to be there, so check that the output from the PSU and that the voltages (HV) are good first, and getting to the Master display driver to be relayed to the player displays.

There are also 5 x 3 Mega ohm resistors, at R15-R19, These are for the cathode "keep alives" and again should be near that value. If the 3 Meg resistors don't look cooked and are within spec, check that you can see an "orange glow" in the displays when the lights in the room are dim or off. If you see a faint glow (some describe it as an 'orange neon dot'), then look elsewhere for the fault.

If you don't see the display glow, check the wiring to the connectors carefully looking for a burnt wire at pins 4J7-1 -2 and -6
on the master display. Do this with the power off, as you are dealing with 100v and -100v DC. If you find a cooked wire, sometimes just cutting the wire back a bit to expose clean metal and then reinserting it firmly in the IDC connector will repair the problem with a bad connection for one of the HV lines. Remove and reseat all the edge connectors on the master display board and especially examine the ones that go to the backbox. You can clean the copper contacts on the edge connectors gently with an eraser to shine up the copper if it's dull or has "dead spots" worn on it. Check any inline connectors as well.

I also recommend disconnecting all the player displays 1-4 at the Master display. Get it working with the just the credit/match and
then with one other display attached, like player 1. Then add back the player 2-4 displays one at a time (you need to power off each time you add or swap a display), testing for correct function each time. You can also swap the player displays as a diagnostic step and carefully observe if the fault(s) stay with the Display in question or move to the new location. Use the "display test" on the diagnostics for this. After the above is checked, perhaps you do have to suspect the IC chips (or for the discrete version the transistors). Depending on whether the Segments or Digits are out, it will point you at a specific IC (or transistor array). Knowing which displays are out helps reduce the fault domain down to one chip. You need be like a detective, following the clues. Having a Master Display Assembly drawing and a schematic on hand will help with this process.

Here's hoping that it isn't one of the UDN6118A-1 (aka UDN6184-5) IC chips that's faulty. Hard to remove from another board in one piece, without a de-soldering station and becoming obsolete.

Also, check that the display blanking connector is in place. This will be a 4 pin connector with a single wire. If this connection has failed or has been unplugged, the game will boot, go into attract and seem to be working, but the displays will remain blank.

===Displays only showing even number===
This is caused by a display signal connector issue. This shows up in pairs; player one and two or player three and four. Likely to be header pins on MPU board connector J5, J6, J7

===Scrolling Digits on Display===
The rather unusual issue of "scrolling digits" on the displays is caused by failed/failing filter capacitors on the power supply board. Over about 40 years of operation, these capacitors begin to fail and no longer effectively filter the high voltages. The OEM capacitors were rated at 100uf/150V. These capacitors can be replaced with 220uf/160V axial capacitors to correct this behavior.

A video of this behavior can be found [https://www.youtube.com/watch?v=QxIRdJ7ecBY here.]

===System 3-6 Displays===

====System 3-6 Master Display Driver Boards====
Master Display Driver Boards came in two versions, discrete and IC based. Williams designed the discrete version when the UDN7180 / UDN6184 Gas Plasma Display Driver ICs became scarce (and they were expensive even then). There are some logic chips that decode the BCD data for the 7 display segments (MC15453 or MC15458) and to buffer and invert the display strobe lines for the digits (MC14069). These buffers and decoders are common to both the D8000 and D8168 versions.

=====Discrete version Display Driver=====

[[File:WMS sys3-6 master display discrete.JPG|300px|thumb|left|Williams System 3-6 Master Display Board (Discrete Components)]] 

The D8168 board uses MPSA92 (PNP in a TO-92 package) and MPSA42 (NPN also TO-92) transistors to drive the Master (Credit/ Match) and player scoring displays. These gas plasma display driver transistors are available today and still very cheap to buy. Unfortunately, this style of board is less common to find in the wild, but actually easier to maintain. At least no one can try to charge you $20+ for an obsolete driver IC.

 

=====IC version Display Driver=====

[[File:WMS sys3-6 master display.JPG|300px|thumb|left|Williams System 3-6 Master Display Board]] 

The D8000 IC version board is composed of ICs that implement the transistor arrays. Usual factory chips are the UDN-7180 for the Segment Driver and the UDN6118a-1 for the Digit Driver. You may find the Digit Driver IC is a UDN6184-5 as well from Williams.
 

The UDN-7180 IC chips are still fairly easy to find. Cost should be reasonable, if you shop / ask around. (Sprague) or uPA6118c may still be available for $3-5 but have a lower breakdown voltage (~85v DC) than original part. The displays run at +/-100v DC as standard and need the higher rated original part which is the the UDN6118A-1 (note we have -1 at the end). The UDN6118a-1 is rare and also becoming very expensive, as much as $20+ for an IC chip.

If you do find the '''lower rated UDN6118a (or uPA6118c)''', then you will need to replace two zener diodes on the PSU to lower the display voltage down from 100v. It's a good idea anyway on a working System 3-7 game. Not overdriving display glass and less stress on the expensive display driver chips will lengthen the life of your game. Arcades sometimes had bright lights or windows, while in your home you won't notice any difference running at a lower voltage.

I usually drop the voltage down leaving the Power Supply to about +/- 90v with 2 x 1n4763a 91v zeners, at locations Z2 & Z4. This seems to work well, but you are still probably driving near the limits of the replacement UDN6118a. Unlike the Bally games of the same era, there is no fine adjustment on the voltage output of the HV section of the PSU.

See the Power Supply repair section for more information about parts to use and other upgrades.

Remember to compare the costs and trouble of repairs with buying a replacement Master Display Driver board:
* If all that is wrong with the Master is that the Credit/Match display is out, but it drives all player displays correctly, in my experience the repair is easier than on the player display parts of the driver board:

* '''Carefully placing a new 6-digit glass against the pins of the non-working display will confirm if it is the display glass or an IC chip that has failed.''' Be Careful of the HV (High Voltages) when doing this, and only hold it by the display glass as it is a natural insulator! It takes a steady hand and some practice, but this test will work on other player displays as well. This usually proves the old display has a digit/segment missing, is 'out gassed' or is just prone to flickering. This isn't foolproof, it works works provided the existing display doesn't have a short. If both displays exhibit the fault, cutting the correct 'leg' or legs in the middle on the old display may help reveal this, and you can bend it back and solder back together if it's not shorted.
** You replace the Master display glass with a standard 6-digit gas plasma display, you can even use an old (but working) player display.
** You can also replace the Master display with a player display that has a digit fault and would otherwise be unusable! It's possible because the '100,000s' and '100s' digits are not used on the Master [x00x00]. So you can take two faulty components (a non-working Master and non-working player score display) and make a working Master Display Driver Board. Pinball repair nirvana.

Once you feel the display glass is good, you can look to the ICs which are dedicated to driving the Master (or Credit/Match) Display:
* Start by testing IC1, a 14069 Hex Buffer/Inverter with your logic probe. Run the display digits diagnostic test, with the Auto/Manual switch in the Auto/Up position. The digits on all displays should be counting 0-9. Test the strobe lines are being inverted. The strobe lines and associated pins are in the diagram given below.

When reading this diagram remember that Player 1&3 Score Displays share Strobes 1-6, while Player 2&4 Score Displays share Strobes 9-14. One strobe for each digit.

The Master Display has 4 digits only: Strobes 7,8,15,16. So if the output pin is not the inverse of the input pin or a signal is missing, then replace IC1. It's available as a 4049U or MC14049UB. Cost is maybe 50 cents, certainly < $1 even in low numbers. Useful chips to buy and have around, as the 4049 is also used on the System 3-7 Driver Board for the switch matrix and on other later games.

[[File:Sys3-7-Displ-Digit-Driver.jpg]]
 
Digit failures will show up in these pairings if they are related to the strobes (so digit drivers):
* Strobes 1-6: shared for players 1 & 3
* Strobes 9-14: shared for players 2 & 4
* The Diagram below is the same for all games, as are the Master Displays which makes them interchangable:
* The Table / Diagram is listed in the most obvious order: Master, Player 1,2,3,4 displays.

This is a clearer Table from the above diagram:

{| class="wikitable"
!colspan="4" |MASTER DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT DRIVER
!STROBE
!4049 INVERTER BUFFER
|-
|align=right|(Left) 10,000||IC4 pin 1 / 18 ||align=center|15 ||IC1 pin 11 /10
|-
|align=right|1,000 ||IC4 pin 3 / 16 ||align=center|16 ||IC1 pin 1 / 2
|-
|align=right|10 ||IC4 pin 5 / 14 ||align=center|7 ||IC1 pin 3 / 4
|-
|align=right|(Right) Units||IC4 pin 7 / 12 ||align=center|8 ||IC1 pin 5 / 6
|}

{| class="wikitable"
!colspan="4" |PLAYER 1 DISPLAY
!colspan="4" |PLAYER 2 DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
|-
|align=right|100,000 ||IC11 pin 1 / 18 ||align=center|1 ||IC2 pin 5 / 6||align=right|100,000 ||IC11 pin 7 / 12 ||align=center|9 ||IC3 pin 9 / 8
|-
|align=right|10,000 ||IC11 pin 2 / 17 || align=center|2 ||IC2 pin 3 / 4||align=right|10,000 ||IC11 pin 8 / 11 ||align=center|10 ||IC3 pin 5 / 6
|-
|align=right|1,000 ||IC11 pin 3 / 16 || align=center|3 ||IC2 pin 1 / 2||align=right|1,000 ||IC12 pin 5 / 14 ||align=center|11 ||IC3 pin 3 / 4
|-
|align=right|100 ||IC11 pin 4 / 15 || align=center|4 ||IC2 pin 9 / 8||align=right|100 ||IC12 pin 6 / 13 ||align=center|12 ||IC3 pin 13 /12
|-
|align=right|10 ||IC11 pin 5 / 14 || align=center|5 ||IC2 pin 11 /10||align=right|10 ||IC12 pin 7 / 12 ||align=center|13 ||IC3 pin 11 /10
|-
|align=right|Units ||IC11 pin 6 / 13 || align=center|6 ||IC2 pin 13 /12||align=right|Units ||IC12 pin 8 / 11 ||align=center|14 ||IC3 pin 1 / 2
|}

{| class="wikitable"
!colspan="4" |PLAYER 3 DISPLAY
!colspan="4" |PLAYER 4 DISPLAY
|-
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
!DIGIT
!(UDN)6184 DIGIT
!STROBE
!4049 INVERTER
|-
|align=right|100,000||IC12 pin 1 / 18 || align=center|1 ||IC2 pin 5 / 6||align=right|100,000 ||IC13 pin 3 / 16 || align=center|9 ||IC3 pin 9 / 8
|-
|align=right|10,000 ||IC12 pin 2 / 17 || align=center|2 ||IC3 pin 3 / 4||align=right|10,000 ||IC13 pin 4 / 15 ||align=center|10 ||IC3 pin 5 / 6
|-
|align=right|1,000 ||IC12 pin 3 / 16 || align=center|3 ||IC3 pin 1 / 2||align=right|1,000 ||IC13 pin 5 / 14 ||align=center|11 ||IC3 pin 3 / 4
|-
|align=right|100 ||IC12 pin 4 / 15 || align=center|4 ||IC3 pin 9 / 8||align=right|100 ||IC13 pin 6 / 13 ||align=center|12 ||IC3 pin 13 /12
|-
|align=right|10 ||IC13 pin 1 / 18 || align=center|5 ||IC3 pin 11 /10||align=right|10 ||IC13 pin 7 / 12 ||align=center|13 ||IC3 pin 11 /10
|-
|align=right|Units ||IC13 pin 2 / 17 || align=center|6 ||IC3 pin 13 /12||align=right|Units ||IC13 pin 8 / 11 ||align=center|14 ||IC3 pin 1 / 2
|}

If that doesn't fix it, next move on to the Segment Drivers:
*Look at IC4, the UDN6118A, follow the steps to do a DMM test of the UDN chip. A trick here can be that all the pins are not used (because of the missing digits, so it is possible to make use of the original UDN6118-A-1 (or UDN6184-5) that has a previous fault and one I/O pair is faulty.

This works for the Master Display, so I would keeep a faulty UDN chips (or a faulty board) for spares. You never know (e.g. there is an ''extra unused pair'' on every UDN7180 type chip pins 1+18 when we get to Segment driver tricks!!! This does not work when you get to for System 7-9 Masters, as all the pins are used.

Pairs that '''are needed''' for IC4 are: (1,18) (3,16) (5,14) (7,12). So you can get away without pairs: (2,17) (4,15) (6,13) (8,11) so you can have up to 1/2 the chip faulty, but it needs to be the right positions without using wire jumpers.

There is a way to test the UDN6118's with the power off and your DMM (multimeter).
*'''With the game OFF''':
**Remove the power in to the Master Display board, connector 4J7.
**DMM goes on the Diode test setting, usually a symbol like this: ->|
**Red lead clipped to ground, I use the ground braid in the backbox, or on the display board connected by a jump lead (alligator clips each end)
**Touch black lead to the UDNxxxx pins 2 through 8
**You should get .5 to .7 for each pin 
**Then touch Black lead on each UDNxxxx pins 17 through 11.
**An open reading (no reading) is the correct result.
**A shorted display glass can show up during the UDNxxxx 11 through 17 test.
[[Image:UDNReading.png|left]]
 

Shorts Are Found in UDN Chip Test 
If a short reading is found in the tested pins (don't test the pairs 1,18 and 9,10), the UDN chip should carefully be desoldered and removed from the board. Take care to preserve this chip, as they are nearly impossible to find and expensive to replace. Now install an IC socket in its place. Repeat the test with no chip installed. If the short is gone, then the UDN chip needs to be replaced. If the short remains, then the display glass needs to be replaced.

Notes on different board revisions:
Williams also used the DI-0512 (Dionics-512) for the Digit Driver IC. I have owned the discrete transistor version, but the Dionics-512 version is even harder to find, and I've not seen one in 7 years of collecting. That's not to say they are not out there.
All the troubleshooting instructions above are intended for the UDN type boards, but the Dionics boards work in a similar way, so consult the schematics. You will also need to make sense of the warnings below.

'''Warnings:'''
These are factory changes, but if you replace or swap chips, you should be aware of the following
* The Display board must run similar chips, so for example all UDN-6118 / UDN-6184 types for the Digit Drivers OR all DI-0512 Digit Drivers (which are longer, meaning they have more pins). They have different power requirements! The two Segment Driver ICs need to match, too. So two MC14548 ICs at IC6 & 7, OR two MC14543 ICs at IC5 & 8. Mix & Match or having all four installed is mental (crazy)! You should have empty pads on the board for the optional IC chips.

* With the DI-0512 at ICs on these boards, the '10K' resistors R1-R14 are all 15K. Adjust the repair instructions below accordingly.
* If IC4 and IC11-14 are UDN-6118 chips, then a +100v trace is cut connecting pin 2 of connector J7 and ZR1 (1N4740A Zener diode) is added.
* With the DI-0512's this trace is left, and there is no Z1 used.

[[File:D8000-Cut-Trace.jpg|300px|thumb|left|Williams System 3-6 Master Display Board]] 
Sometimes a HV arc can occur between two pads on the Master Display board, and if this happens it will blow out the HV section of the PSU (power Supply Unit). If you have the UD7180 version of the System 3-6 Master Display board, it may be worthwhile taking this '''easy step''' to prevent a problem:

There is an unused track on the front of the board near to the bottom right corner of the Master display glass. The top round pad in this picture is unused on the UDN7180 version but goes to the +100v supply at Pin 2 of 4J7. Click to expand the picture at left for a better view.
 
It appears that the pad shorted out to the ground track that goes around both of the round pads. Cutting the track to the top round pad as shown in the picture (with the board removed from the game) will cause no problems for the displays on your game. And it could prevent disaster. A short could damage the HV section of the PSU, even the Master Display board itself. I have seen it happen, so better safe than sorry. BTW- This track '''should not be cut''' if the Dionics Digit Driver ICs are installed. The writer has owned many games and has never seen a board with the Dionics ICs.

==Sound / Speech Board Issues==
Sounds and speech are one of the most important parts of a pinball game for me.  Few things are more depressing for me than the sound of a pinball rolling around the wood with no background noises and without sounds of points being scored.

This section deals with the square sound board Type 2 ( System 6 & 7, with or without the speech "daughter card"). The Williams part number is 1C-2001-146-x, although much of the information applies to the Type 1 boards (System 3 & 4).
----
A description of the sound board Type 2:

* The sound board is actually a "mini-MPU" board running a 6808 CPU and a single 6821 PIA. So read the MPU board sections about the replacing sockets and the reset circuit as it will work in a very similar way.
* It has an external 6810 RAM for the CPU registers / 'stack'. This can be replaced by internal RAM in the 6802 CPU if that is used.
* It has it's own PSU (Power Supply Unit) and takes ~18v AC voltage directly from the games mains transformer and rectifies it to DC voltages that provide the +5v logic to the ICs and +12v for the CPU reset circuit.
* It provides -12v DC only used on the speech card for IC2 & IC3 the two 1458 OP Amps. They act as mixers for the analogue sounds and digital speech.
* A single 2K 2716 Eprom (ROM) which contains program instructions that 'boot' the CPU and code to create the sounds. Different ROM versions are containing specific sounds are numbered: Williams' Sound ROM 1, Sound ROM 2, Sound ROM 3...

The last item deserves some explanation. The Sound ROM does not store sounds as samples, but as mathematical 'strings' which describe parameters such as attack, frequency, decay and echo. So the board functions as a synthesizer, rather than playing a WAV file or compressed sound like an MP3 player today. In fact a 2K sample at 22K Hz sample rate could last about 1/10 of a second.

The 4K 2532 Eproms on the Speech Board can hold sampled sound but at very low quality. [[Black Knight]] used 4 Speech ROMs for a total of 16K and could speak about 20 words along with the famous laughter. Earlier games having 3 Speech ROMs Like Gorgar or Firepower could speak only about 11 words using 3 x 2532 ROMs.

'''Why did they provide a different PSU for the Sound card?'''
This early Williams game design could be for ground isolation, perhaps to provide a cleaner sound by avoiding interference from the other components which created RFI. Notice that I used "early Williams game design" and "cleaner sound" were just used together in the same sentence. I have also seen Sound Boards where the BR1 was missing and replaced by 4 x diodes, which also works. Two were mounted on the front and two on the back, with the bands on the diodes all pointing in the direction of TP1 (+12v). Start at 1N5401, rated 100v @ 3A.

Understanding this background should help pinpoint the source of problems with Sounds and Speech on games of the early 80's.

===Useful Sound Board Repair Links===
Leon Borre's work is a good starting guide for Williams sound board repair. He was a clever guy in Belgium, who developed special test ROMs for lots of pinball systems, including Williams System 3 through 7. ''' I can't thank him enough here!''' He developed a test chip that can be downloaded and burned to a 2716 Sound EPROM, which will start the CPU, "pulse" the PIA and also test the memory. It's harder to do any advanced fault repairs without this test ROM. So it's a good place to start if the sound board doesn't boot at all. Leon's technical article pertaining to Williams System 3 through 7 sound can now be found [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair here].

Dave Langley's site [http://www.robotron-2084.co.uk/techwilliamshardwareidsound.html robotron-2084.co.uk] has a clear diagram of jumper settings for most games on Williams Type 2 boards. Check jumpers first, W1 must be present if no speech board is attached.

===Testing for a Sound Board fault===
Before starting to repair a Williams sound card, first determine that there is actually have a sound board problem! Do the sounds work correctly from the sound board 'self test' by pressing the diagnostic button? Have you followed the diagnostic procedures in the game manual and checked the 'Solid State Flipper Maintenance Manual' or equivalent for the specific game? There will probably be a fault on the sound board if the diagnostic test on the sound board produces nothing (or the wrong sounds) '''and''' grounding the input pins won't work. See the 'sound selects' section for specific games below. Check out the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting section] first. After reviewing it, here are are some specific things to eliminate first:

* Bypass the volume control in the cabinet by removing the connector at IOJ4 and jumpering pins 1 & 2. It will be really loud (full volume in fact) so a couple K ohm resistor (3K?) looped around those two pins will substitute for the volume pot and save your ears.
* Take the sound board out, leave all the connectors still plugged in and the game running.
** The speaker and volume control can be set as above.
** Touch the back of the sound amp at IC1 with a finger - it's just under the Volume control connector J2 which was jumpered and has 5 legs. Not hearing this hum could be a missing +12v or a bad amp IC.
** A loud loud hum should be heard from the speakers, this proves the TDA2002 sound amp is working and also that the speakers are capable of producing sound.

Treat the sound board as a mini-MPU board (but with an on-board PSU) and all the usual fixes apply:
* Test there is around 18v AC coming in to the sound card. It's directly from the transformer to connector 10J1 and then fused with 2 x 8A fuses.
** Are both fuses good? Take them out and test them.
**Is the voltage getting further than the fuse clips? Are the fuses hot to the touch after the power is switched off? This may indicate high resistance at the fuse clips.
** Pin 5 of 10J1 is the 'center tap' or reference for the AC. There should be about 9.6 V AC between pins 1 and 5, and the same voltage between pins 9 and 5.
* Use the test points to measure DC +5v +12v and -12v. A short-cut (and much easier) is to touch the Red test lead to the left side leads of the 3 big capacitors, with the black lead on Ground which is the metal trace on the edge of the board.
**Remember -12v is only needed for the speech board, and even around -10v will normally be fine.
**Don't worry if the voltages aren't perfect (especially the +/-12v DC which is unregulated). Only the +5v needs to be in a narrower range (4.8-5.2v).
**No +5v with +12v present suggests the 1 amp '7805 5v regulator' at IC8 is faulty. It looks like the TIP-xxx transistor as it is in a TO-220 case, with a heatsink. Measuring +12v input on the top pin and no +5v output on the bottom pin will confirm this diagnosis. Obviously the CPU (and other ICs) can't run without the +5v logic voltage.
* If there are Scanbe sockets, replace them first, including the ROM socket. The PIA can be left alone for now if it's soldered directly to the board and not socketed.

Read the MPU board repair and troubleshooting if the board still won't 'boot' (the CPU, working RAM and reset circuit are very similar).
** Because there are no LEDs to show the board is 'locked up', you will need to look at pins 9 - 20 & 22-33 on the CPU for any activity with a logic probe. If the CPU has started, there should be some activity on these address and data bus lines. If they are 'dead', then the CPU has not started.
** If you look at the CPU bus lines with Leon's sound board test ROM (instead of the sound ROM) you can see which lines are missing, and also will see the PIA lines 'dance' as he calls it. The PIA I/O lines strobe Hi/Lo/Hi/Lo if they are working as they should. The test ROM will need to be burned on a 2716 Eprom.
** Review Leon Borré's [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair Williams sound board article] for advanced troubleshooting. You can fix boards more easily with his free test ROMs.
** Note: The the test chip will not start on a Type 2 board with jumper W1 missing, unless the speech card is also connected. Mine didn't start "pulsing" without the speech card. Because of this, here's a ''key tip'': '''Jumper W1, and set DS1: SW1 and SW2 to OFF and run without a speech board''' until the sound is working 100%. Do this now if you haven't removed the speech board already, it may not be obvious at first, but you have to get back to a basic setup and work forward from there.
See also [[Williams_System_3_-_7#Put the Sound/Speech Board on the Bench|Advanced Sound/Speech Board Repair on the Bench]]

===Back to Basics===
[[File:WMS_Sys6-7_Sound_W1_Jumper.JPG|left|300px|thumb|Temporary W1 jumper installed]]
[[File:WMS Sys6-7 Sound Pot Alternate.JPG|right|300px|thumb|Bypassing the volume control]] 
The next step, once you have verified voltages is to remove the speech board (if one is fitted) and jumper W1. Verify W1 is present for any board you are working on, as no sound gets to the audio amp without a speech board or jumper W1 present. 

To bypass the volume control, a 470Kohm resistor can be installed across pins 1 & 2 of connector 10J4. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped and installed in a .156" housing. Although a 470Kohm resistor is used in this example, other values can be used to obtain the desired volume. 470Kohms sets the volume to medium loudness. 

The .156" set up can be used on all Williams sound boards from System 3-7 games and 9-11 games too.
 

===Modification for Noisy Type 1 Sound Boards===
On the Type 1 sound boards, Williams did not use a small value bypass capacitor on the input to the 7805 +5V regulator as recommended by the manufacturer. This bypass capacitor is used to keep noise off of the +12V voltage rail, which is used by the power amplifier IC. Installing a .22uF ceramic capacitor across the input pin (pin 1 - left pin from front) and ground (pin 2 - center pin) of the 7805 regulator can significantly reduce the amount of noise and hum on these sound cards. Important note -- the Williams Type 1 Sound Board schematic diagram has an error. Pin 1 is the input, pin *2* is center pin and connected to ground and pin *3* is the output.

===System 4-6 Sound Selects===
Press the diagnostic switch on the Sound Board. When sounds do work on the sound board self test, but you get missing or incorrect sounds during a game, then a simple test for all models of sound card is to ground the input pins. This gives you an indication that the sound board is working, as each pin should produce a distinct sound. For Type 2 boards (square ones) that's 10J3 pins 2-4 and 7, pin 1 is on the right, It may also be the same pin locations on the Type 1 boards (Flash, and other System 3 & 4 games).

[[File:WMSType1SoundBoardBenchTestAnnotated.jpg|300px|thumb|left|Type 1 Sound board connections and grounding sound select header pins. Here, one end of a jumper wire is clipped to the ground plain of the board itself.]] 
Grounding those sound select pins is exactly what the Driver Board does during a game solenoid diagnostic test. It fires solenoids 9-13 to ground the select pins and this triggers 'sound calls' on System 3-6 games. If grounding the sound board pins works, then suspect cabling between the Sound Board and Driver Board or faulty transistors (or pre-drivers) on the Driver Board for the System 3-6a games. You can ground the transistor's metal tabs from the chart below, if this does not produce sounds then the cabling between Driver and Sound Boards is then suspected.

Please note that '''grounding the center tab of a transistor''' ''does not test the transistor(s)'', it only proves that the cabling from that tab out to the sound board select pins has continuity. It does not prove the transistor(s) work as a switch under the CPU's control.

This is true for '''''any testing of solenoids (or flashers) by grounding transistor tabs'''''. It only proves that the cabling from the Driver Board out to the device is intact, and that the device has power and can function when grounded.

So the Solenoid portion of the diagnostic test will help you figure it out for a System 3-6 game. It can perhaps help for System 7 game too, although remember that sound calls are triggered from the MPU board instead. 

On System 6 (and earlier) you will have a fault on the Driver Board, and specifically the solenoids in the range 9-13 if the following are true:
* The self test on the sound board works as expected,
* Grounding tabs on the Driver Board produces the same sounds,
* But the game's diagnostic tests do not trigger sounds when testing solenoids number 9-13.

If it fires the device, the problem is the transistors or the logic on the driverboard and then the PIA upstream from them. You should first replace both the associated TIP 120/102 and the matching 2n4401 pre-driver transistors on the Driver Board (a fairly easy fix) and re-test. Then follow Driver Board testing and repairs.

If a transistor gets shorted 'on' (or a 7408 IC is faulty) and one of the sound selects is constantly grounded from the Driver Board, you will certainly get fewer and usually wrong (or no) sounds played. This type of problem can be chased around for hours, if you don't work logically through the problem.

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="25%" border=2
|+'''Driver Board Positions'''
|-
| 2J9 ||10 || 9 || 6 || 7 || 8
|-
| 2J9 ||11 || 12||13 || 14 || 15
|}

Blue shows the 5 Sound Select Transistors on the bottom two rows of a System 3-6(a) Driver Board.

If diagnostics don't work as you expect, as explained, ground the metal tabs of the TIP122 transistors (briefly - they may be real coils or flash lamps!) on the bottom 2 rows of the driver board. You should hear 5 different sounds. The first 3 sound select transistors are at the bottom left of driver board. The first two the next row up are the remaining sound select transistors (solenoids 9-13 as shown on the chart above).

You can of course also '''turn off the game''' and measure between the center tab and the input pins on the sound card with an DMM (meter set on continuity or Ohms). If you get high resistance readings, check for cold solder joints on the input pins of the sound board at 10J3. Then check the output pins on the Driver board at 2J9. Reflow the solder on all these pins. Do the other pins on the sound board at the same time.

Another tip is that you should see the center tab of the Blue "sound transistors" running at about +5v DC on the driver board with the game running. If a tab is at zero volts, and others are at +5v then that grounded select points to the problem. Other TIP122 transistors could be at the coil potential, so have your DMM set to voltage and +50v or above for this test if it does not 'auto-range'.

If you get this far and can get 5 distinct sounds, then the problem is not the sound board, nor the connection to the driver board. With System 3-6, this could still be on the driver board and specifically:
* a power transistor TIP122,
* a matching 2n4401 pre-driver transistor ,
* a 7408 logic IC
: and finally
* a 6821 PIA for Solenoids at IC5. As this is a 40 pin IC, it should be replaced as a last step.

At this point just follow the driver board testing and repair guide to get further.

Complete list of Driverboard 2J9 pins and the associated transistors (for Sys3-6) are:

{| cellspacing="0" cellpadding="3" width="50%" border="2" bordercolor="#0"
|+'''System 6 Driver Board 2J9 Sound Outputs'''
|-
| Pin
| Sol.
| Function
| Transistors
| Wire Colour
|-
| 2J9 P9
| # 9
| Sound Select 0
| Q31 / Q30
| Brown / Black
|-
| 2J9 P8
|  (*)
| Key
| 
| N/C
|-
| 2J9 P7
| #10 
| Sound Select 1
| Q33 / Q32
| Brown / Red
|-
| 2J9 P6
| #16
| Coin Lockout*
| Q45 / Q44
| Brown / Grey
|-
| 2J9 P5
| #15
| Depends on game*
| Q43 / Q42
| Brown / Violet
|-
| 2J9 P4
| #14
| Credit Knocker*
| Q41 / Q40
| Brown / Blue
|-
| 2J9 P3
| #13
| Sound Select 4
| Q39 / Q38
| Brown / Green
|-
| 2J9 P2
| #12
| Sound Select 3
| Q37 / Q36
| Brown / Yellow
|-
| 2J9 P1
| #11
| Sound Select 2
| Q35 / Q34
| Brown / Orange
|}

* Typical functions, but depends on the game.

List of J3 sound select pins on the System 6 or 7 sound board are:

{| cellspacing="0" cellpadding="3" width="50%" border="2" bordercolor="#0"
|+'''System 6/7 Sound Board Inputs'''
|-
| 10J3 Pin
| Sol.
| Function
| Wire Colour
|-
| J3 P3
| # 9
| Sound Select 0
| Brown / Black
|-
| J3 P2
| #10 
| Sound Select 1
| Brown / Red
|-
| J3 P5
| #11
| Sound Select 2
| Brown / Orange
|-
| J3 P4
| #12
| Sound Select 3
| Brown / Yellow
|-
| J3 P7
| #13
| Sound Select 4
| Brown / Green
|-
| J3 P1
|  (*)
| Key
| N/C
|}

On System 6, using only 5 solenoids for sound limits the number sound and speech calls. Makes 25 = 32 so only 31 usable combinations, a call of all 0's being null. But (using Firepower as an example) you then can have all the combinations of maybe 20 sounds plus the 11 speech phrases it "knows". So it's enough given the small amount of sound and speech memory they had to work with at the time. In fact it's amazing! For more background, see: An interview with [http://www.firepowerpinball.com/downloads/Eugene_Jarvis_Interview.pdf" Eugene Jarvis], the sound engineer and programmer for Williams at the time.

Changing the sound board won't cure the problem of a missing solenoid signal, and a major clue is that the sound board tests good, and is also good when grounding the 5 input pins at (Board #10) J3 input connector on the sound board.  While the "in game" sounds or game diagnostics will play incorrectly or have missing sounds. For example, an email from someone said that their Firepower game could say "Power" but not "Fire"! A fairly easy diagnosis if you know the game, it pointed to transistor Q35 (a TIP122, a better replacement is the TIP102) which was completely missing from the Driver board. Transistors on the bottom row often get bent back and forth and snap clean off - hard to spot if you aren't familiar with inspecting the Driver Board.

That transistor's center tab connects to 2J9 pin1 and solenoid 11 then fires sound select #2, according to the table above. Without that sound select being triggered, only half the game sounds could be produced (24-1> = 15). "Fire" was one of the missing sounds, there were others but they may have not been so obvious to the owner. They would not be listed in the manual as a sound triggered by an achievement (making to rollovers F-I-R-E in this case). The point is to use all the information available to help determine the root cause of your fault.

===System 7 Sound Selects===
By System 7, Williams had stopped using solenoids to fire sounds and had added a dedicated Sound/Comma PIA on the CPU board to trigger sound/speech. This meant more playfield coils and even flash lamps were now possible, as the Driver Board wasn't used to trigger the Sound Board.

On a Black Knight and later games, the fault could still be on the MPU board. Perhaps PIA 5 (IC36 a 6821 PIA) is suspect as this drives the sound board (and display commas) only. Again you can trigger sound selects by grounding pins on the sound board, and then move back to the header pins of the MPU at 1J8. The pins are12,11,10,9,8 in that order for the 5 sound selects 0-4

The outputs of the IC36 PIA at PA0-PA6 connects to 1J8 starting at pin 12 (1J8 P12) and run backwards numbered as the Sound Selects in the table below:

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="25%" border=2
!colspan="3" |'''SYS 7 1J8 Sound & Comma Outputs'''
|-
! Pin
! Function
! Wire Colour
|-
| 1J8 P1 || Comma 3 & 4 || Brown / White
|-
| 1J8 P2 || Comma 1 & 2 || Violet
|-
| 1J8 P3 || Key (*) || N/C
|-
| 1J8 P4-7 || No Connection || White
|-
| 1J8 P8 || Sound Select 4 || '''Yellow'''
|-
| 1J8 P9 || Sound Select 3 || Green
|-
| 1J8 P10 || Sound Select 2 || Blue
|-
| 1J8 P11 || Sound Select 1 || Red
|-
| 1J8 P12 || Sound Select 0 || Red / '''Yellow'''
|}

In theory Williams had the ability to trigger Sound Selects 0-6 from the System 7 MPU board, and could have programmed 127 sound / speech calls. But the sound boards at the time never used that many, to my knowledge. So you only need to worry about the same 5 sound selects 0-4. Be sure to first '''''check the output pins at 1J8 on the MPU Board for cold solder joints''''', before replacing the 40 pin PIA.

===Put the Sound/Speech Board on the Bench===
By this point, it is likely that there is a sound board fault. If you don't feel comfortable troubleshooting or don't want to get involved with low level board repairs, there are repair services available--check pinball communities/forums for recommendations. [[Williams_System_3_-_7#If All Else Fails|Reproduction sound and speech boards]] are also available if all else fails.

[[File:WMS Sys6-7 Sound Pinouts.JPG|300px|left|thumb|WMS System 6/7 Sound Board Pinouts]] 
If none of this helped so far, read the rest of the section below. The boards will likely need to be bench tested in order to proceed with testing. Any PC power supply has the +12v and -12v DC that will be necessary for bench testing, which are normally located on the motherboard connectors. The older the PC power supply, the better, as they will have a power switch, but there are two pins that can be jumpered (or connected to a switch) to enable the voltage outputs.
 

[[File:WMS Sys67 Sound Bench.JPG|300px|left|thumb|WMS System 6/7 Sound Board Connected to an AT Power Supply]]
[[File:WMS Sys67 Sound Test Points.JPG|300px|right|thumb|WMS System 6/7 Sound Board Connections for an AT Power Supply (Four Sound Board Test Points)]] 
Search for an "AT Power supply" on the web for the connector locations or measure them with the DMM. The wires on one example were colored Yellow (+12v) and Blue (-12v). Ground was black as usual. Sliding the existing pins from the motherboard connector housing, and they will potentially fit right in a .156" socket to connect to the sound board. The +12 and -12 goes to the outsides of a 9 pin connector (pins 1 & 9) and the ground to the center pin (pin 5). It doesn't matter which way around the connector is installed--if the Bridge Rectifier (BR) is working it will sort it out by conducting through the correct diodes. 

Another method is to connect the AT power supply connections with alligator test leads directly to the four test points on the sound board. However, this method will not ensure that the bridge rectifer on the sound board is working or not.
 

At this point refer to [[Leon_Borre_Williams_Early_Sound_Repair|Leon Borre's sound board test link]]. He has an excellent approach to a sound board that is dead. A copy of his sound test ROM will need to be burned to an EPROM. A logic probe (under $20) will also be needed, but Leon describes how to make an LED test probe with some wire, an LED, and a resistor which costs a few cents. The logic probe will be more versatile and easier to use. As mentioned before, the Test ROM can check the CPU, memory and also exercises the PIA inputs/outputs. An added bonus is that the test ROM will allow the board to boot, even though there are faults on the board.
 

===Checking for Sounds Prior to the Sound Amplifier===
[[File:WMS Sys6-7 Sound Preamp Probe.JPG|300px|left|thumb|An unamplified speaker used to probe for sounds before the sound amplifier]]
A method to test for sounds prior to the amplifier is to check the output of the D/A converter. This can be accomplished by building a speaker set up. It starts with a low wattage speaker, which does not need amplification to produce sounds. A speaker from an old computer case is a great source. After acquiring a speaker, solder two wire leads to it. Then, solder an alligator test clip to one of the leads, and a small piece of solid, copper, house wire (14 or 12 gauge romex works well) or a small finishing nail to the other lead. The second lead will be used to probe the sound output before amplification. This speaker test set up can be used on any other brand sound board too. 

After the speaker test set up is constructed, clip the alligator test lead to ground. Then, place the probe lead on the "C" collector leg / solder pad of the Q2 transistor, as shown in the picture. Once the probe is in place, press the sound board test button. The speaker will have to be placed close to one's ear to hear the sounds, if any sounds are being output. If the sounds are being heard, either the amp (IC1 - TDA2002) has failed, has lost connection (cold solder joints), or is not being powered properly. 

Normally the probe would be used to check the sound output right on the leg of the D/A converter (IC13 - 1408). However, pin 4 of IC13 (the output) is adjacent to pin 3, which inputs the -12vdc power to the D/A converter. It is much safer to use the collector leg of Q2 as a probing point to avoid shorting pins 3 and 4 together. 

Note that the if the 1408 DAC has failed, it can be subbed with the more readily available DAC0808.
 

===Getting Sound and Speech Working Together===
The very first thing is to make sure you have the correct jumper settings and ROM types.  You can NOT "mix and match" sound and speech ROMs as you like.

My experience is on Williams System 4-7 pinball where the Sound ROMs are 2716 Eproms and the Speech are always 2532 Eproms. The exceptions are video games (and a few pinballs), such as Defender, Sinistar, Robotron and Joust which use a 2532 on the sound board ROM and each has special jumper settings.

'''You need the correct Sound ROM type for your game's Speech ROMs'''.

Firepower '''and''' Alien Poker both use "WMS Sound ROM 3" no matter '''what''' the Alien Poker manuals (or ROM download archives) say. It's the only way I ever got speech to work on my Alien Poker. If you have [[Blackout]], you will need a 2716 Sound ROM 2 to go with Blackout's 2532 Speech ROMs.

This is mainly a warning if you will be plugging together different boards on a workbench or when troubleshooting a problem, don't trust that all Sound ROMs work with all speech boards !

Here is a diagram on placement of the Speech ICs, as the layout of the ROMs aren't very logical. Check they are correct. This diagram works for any of this type of Speech Daughter board. Replace your game number nnn in ST-nnn-ROM# format.
See examples for [[Firepower]] (497), [[Alien Poker]] (501) and [[Black Knight]] (500), which are among my favourites.
The information is provided for clarity, it is recommended that you replace Original Speech Mask Roms with newer 2532 Eproms. 

'''Note:''' unless a System 9 speech board is available with jumpers, 2732 Eproms cannot be used for the speech board, unless the board is [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified].

'''Speech ROM IC socket locations:'''
[[File:Speech-ICs.jpg]]

Also distrust the switch settings and be aware that you could have a faulty DIP switch on the Type 2 board. It can happen! Test by removing the 2-way switch, or jumpering across the back of the switch. If DS1-2 is not connecting, you will hear sounds- but no speech.

The clue here is that if you press the sound board diagnostic switch, you hear BOTH sounds and speech.
[[File:WMS Sys67 Speech Scanbe.JPG|300px|left|thumb|System 6/7 Speech Board with Scanbe Sockets]]
[[File:WMS Speech Scanbe Socket.JPG|300px|right|thumb|Identifying Scanbe Sockets]] 

: Speech ROMs and Speech Board sockets should eliminated, you can measure continuity on all pins from the Speech ROM to the bottom of the socket or back of board before replacing Sockets. If they say '''SCANBE''' then replace them as they will be faulty.
: Gaps in speech usually point to a faulty Speech ROM, look in the manuals for which ROMs hold the missing words.
: Suspect the logic selects on the sound board or the 40-way IDC connection between the speech board to the sound board. Watching for 'chip select' pins 20 on each Speech ROM with a logic probe will help you see the chips being selected by the sound board. Again knowing which ROMs hold the missing phrases will help. No speech selects can point to the interboard cables, or missing outputs from IC2 (a 7442 decoder) '''on the Sound Board'''.
:Bear in mind that the Speech card is an 'expansion board' to hold ROM space for the speech and the digital/analogue mixer. The address and data buses extend across the '40-way' IDC connector in a similar way to the connector between the MPU and Driver Board. Except the connector solution is more robust and IDC was still used until recently to connect IDE PC hard drives.
 

Other problems that could cause sounds but missing speech include:

* W1 is jumpered,
* W9 is NOT jumpered (W4 is probably in place),
* IC7 (inverter) faulty,
* IC10 (6821 PIA) is faulty (use Leon's Sound Board test chip)
* Faulty speech board (no speech) or speech ROMs are installed incorrectly

Switch 2 MUST be ON for speech. OFF for no speech.

Switch 1 selects between Tones and Synth Sounds.
ON for musical tones (more like bings and bongs),
OFF for Synthesized Sounds.

{| bordercolor="#0" cellspacing="0" cellpadd ing="3" width="10%" align="left" border=2
| SW 2
| ON
|-
| SW 1
| OFF
|}

    '''DS1 Set correctly for Sounds and Speech.'''
 

{| bordercolor="#0" cellspacing="0" cellpadding="3" width="10%" align="left" border=2
| SW 2
| OFF
|-
| SW 1
| OFF
|}
     '''DS1: Set for Sounds only.'''

     You will also have to '''jumper W1''' if this is not in place.
 

==Speech Board Issues==
===Common failure parts===
[[File:System7SpeechBoardBefore.jpg|left|thumb|300px|Speech board sockets. These are Molex, but "they gotta go".]]
[[File:System7SpeechBoardAfter.jpg|right|thumb|300px|Nice twin wipe sockets, which are preferred over machine pin sockets.]] 
The first and most important action when debugging a Speech board is to eliminate all of the common failure issues. With these issues out of the way, it is much easier to focus on the real issues preventing proper operation. And, eliminating these typical trouble areas almost always brings the board back to full operation.

The most frequent reason for failure of the speech board are the OEM sockets. ScanBe sockets, or white sockets pictured here, should be replaced. If a ROM can be easily removed using only your fingers, the socket should be replaced.

Also check the ribbon cable to the sound card. It breaks frequently at pin 1 which carries the 5V Analog voltage. If you replace the cable make sure that you do not damage the J1 connector. The part is either NLA or so obscure no one stocks it. Fortunately you can gently pull off the cover and reuse it with a new cable. The counterpart is a standard ribbon connector and must be replaced. 

If your speech is garbled and you replaced the MC1458 chips the 55516 CVSD at location IC1 might be bad. This is somewhat rare but not unheard of. The part is long since obsolete and hard to source. It can be replaced with a 55532, 55536 or 55564. Only the 55564, which was used up to the Williams WPC era, seems to be somewhat available. Check your favorite pinball shop for it. 

As with all electronics other parts can fail but the above parts are responsible for around 95% of all speech card failures.
 

===Using the Sound Board Test ROM===
Leon's test ROM and instructions will be very useful. The ROM and instructions are available [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_Early_Sound_Repair here].

Note: The the test chip will not start on a Type 2 board with jumper W1 missing, unless the speech card is
also connected. Mine didn't start "pulsing" without the speech card. You also need
to put the Test code on a 2716 Eprom.

Here's a key tip: Jumper W1, and set DS1: SW1 and SW2 to OFF and '''run without a speech board''' until the sound is working 100%. Do this now if you haven't removed the speech board already.

This may not be obvious at first, but you have to get back to a basic setup and work forward from there.

The following is an attempt to list notable Williams games that used these boards.

There are conflicting lists, Hyperball could be a 2532 ROM #8. as the file hypsnd12.532 has a checksum of 0x25A8 - which doesn't match other sound ROM images. So the list is not perfect. Some corrections have been as of Feb 2011 after more research. If you have updates or can confirm Williams sound ROM numbers (and compared checksums) then please go ahead and edit this table.

The games with speech in the first table are right, I'm less happy with the Video games and Hyperball.

Williams Pinball Games which use a Type 2 Sound Board and a Speech Board:
{| cellspacing="0" cellpadding="3" width="50%" align="left" border="2"
!NAME
!SYS
!GAME
!WMS SOUND ROM
|-
| Blackout
| 6
| 495
| Sound ROM 2 
|-
| Gorgar
| 6
| 496
| Sound ROM 2
|-
| Firepower (r)
| 6
| 497
| Sound ROM 3
|-
| Black Knight(r)
| 7
| 500
| Sound ROM 5
|-
| Alien Poker
| 6a
| 501
| Sound ROM 3 confirmed
|-
| Jungle Lord
| 7
| 503
| Sound ROM 3
|-
| Pharoah
| 7
| 504
| Sound ROM 6
|}
 

(r) Steve Ritchie Game Design

Video Games with Sound and Speech Board:
Sinistar (cockpit front) & Upright, Type 2,VIDEO ROM 9

Pinball Games with Sound Boards Only:
{| cellspacing="0" cellpadding="3" width="50%" align="left" border="2"
! NAME
! SYS
!GAME
!WMS BOARD, SOUND ROM
|-
|Flash (r)
|4
|486
|Type 1 Board, ROM 1*
|-
|Time Warp
|6
|489
|Type 1 Board, ROM 1
|-
|Stellar Wars (r)
|4
|490
|Type 1 Board, ROM 1
|-
|Laser Ball
|6
|493
|Type 1 Board, ROM 2
|-
|Scorpion
|6
|494
|Type 1 Board, ROM 1
|-
|Algar
|6a
|499
|Type 1 Board, ROM 4
|-
|Cosmic Gunfight
|7
|502
|Type 2 Board, ROM 12
|-
|Solar Fire
|7
|507
|Type 2 Board, ROM 7
|-
|Hyperball
(n)
|7
|509
|Type 2 Board,
SPECIAL ROM 8 ?
|-
|Barracora
|7
|510
|Type 2 Board, ROM 4
|-
|Time Fantasy
|7
|515
|Type 2 Board, ROM 13
|-
|Warlock (pin)
|7
|516
|Type 2 Board, ROM 14
|-
|Defender (pin)
|7
|517
|Type 2 Board, ROM 15
|-
|Joust (2 player pin)
|7
|519
|Type 2 Board, 
SPECIAL Snd_IC12.532 ROM
|-
|Laser Cue
|7
|520
|Type 2 Board, ROM 3
|-
|Firepower II (m)
|7
|521
|Type 2 Board, ROM 13
|-
|Star Light **
|7
|530
|Type 2 Board, ROM 3 
ROM 4 is on my game!
|}
 

(r) Steve Ritchie Game Design

(m)  Mark Ritchie Game Design

(n)  Not a Pinball, a gun game that shoots tiny pinballs.

* Sound ROM 1 was used from World Cup #481 to Scorpion #494, but not Laser Ball from my notes.

** Quite a rare and beautiful pinball. Only 100 were produced, the last Williams System 7.

Here is some useful [http://pin-logic.com/early_williams_pinball_game.htm pinball sound file checksum] information. At [http://pin-logic.com Tom Callahan's pinlogic.com]

{| cellspacing="0" cellpadding="3" align="left" border="2"
!NAME
!WMS BOARD VIDEO ROM
|-
| Bubbles
| Type 2 Board, VIDEO ROM 5
|-
| Defender (Video)
| Type 2 Board, VIDEO ROM 1
|-
| Joust (Video)
| Type 2 Board, "VIDEO" ROM 4 
(Checksum matches ROM 4 from Algar and Barracora)
|-
| Robotron 2048
| Type 2 Board, VIDEO ROM 3
|-
| Sinistar (cockpit rear)
| Type 2 Board, VIDEO ROM 10
|}
 

Please Note: VIDEO ROMS and those for Joust (a 2 player head to head pin) and Hyperball are 2532 Eproms

An annoying fact is that from around System 7, most of the WMS sound ROM files are all named something like '''SND_IC12.716 ''', which makes them harder to identify.

===Running a Type 2 Sound Board with a 6802 CPU===
You might not have an 6808 CPU, or you might upgrade to a 6802 because then there is one less IC (the 6810 RAM) to go wrong. You can leave the 6810 (as it's not socketed) if the card functions with it in place.

You can get the Type 2 board to run on a 6802 CPU, without a working 6810 RAM in IC11. To do this you cut a track called W14. It isn't a 0 ohm resistor (or a real jumper), it's a track located under R30, the 3rd resistor in from Left on the Bottom Left of the board. W14 grounds pin 36 of the processor for a 6808 CPU.

If you want to use a 6802, you cut the track W14. Pin 36 will go high through the 4.7K "pull up" resistor at R30. You could then remove the 6810 RAM as the 6802 has internal RAM. My advice is again to just '''''leave it in place''''' if the card functions with it there. I had to rework tracks damaged by removing a 6810 on one sound board being repaired. Avoid making extra work for yourself, and '''''spend more time playing pinball'''''. That way it can be reverted back to 6808 operation in future. Good instructions are currently at [http://www.robotron-2084.co.uk/techwilliamshardwareidsound.html www.robotron-2084.co.uk]. A useful site for arcade video and pinball and Dave has a nice Defender pinball to look at while you're there.

===Modifying the System 6/7 Speech Board to Use 2732 EPROMs===
The original System 6/7 speech board is setup to only use 2532 EPROMs. With the following simple modifications, a speech board can use 2732 EPROMs instead, if the need arises. Please be aware that although these modifications are reversible, it is not nearly as easy to change a modified board using 2732 EPROMs back to a board which uses 2532 EPROMs. 

Procedure:

#On the component side of the board, there is a trace which runs beneath the ribbon cable connection and between pins 11 and 12 of U5 (the lowest two pins on the left). Cut this trace.
#Turn the board over to the solder side. The orientation of the board in the pic below is with the ribbon cable connection on the right.
#Locate pin 18 of U5. There is a trace between pin 18 of U5 and a via down and to the right of it. To verify the correct via, check continuity between pin 13 of the ribbon cable (fourth pin up on far right of the ribbon connections) and the via. Cut the trace between this via and pin 18 of U5
#There is another via slightly down and to the right of the previously discussed via. This second via will have continuity between it and pin 12 on the ribbon cable (third pin up on far left of the ribbon connections). The via will also have continuity between pin 21 of U5. Using wire wrap or a thin gauge wire, tie these two vias together.
#Locate pin 18 of U5 and pin 12 of U4 (down and to the left of U5 pin 18). Again using wire wrap or a thin gauge wire, tie pin 18 of U5 to pin 12 of U4.

<center>
<gallery widths=300px heights=300px perrow=2 caption="System 6/7 Speech Board 2732 EPROM Modification">
File:WMS Sys67 Speech 2732 Mod Front.JPG|<center>Trace cut on component side</center>
File:WMS Sys67 Speech 2732 Mod Back.JPG|<center>Trace cut and two jumpers added on solder side</center>
</gallery>
</center>

 

===Replacing the on-board volume control with a remote volume pot (System 4)===
[[File:DSC0760.jpg|300px|thumb|left|System 4 original volume pot]]
[[File:DSC0761.jpg|300px|thumb|right|Connector 10J4, with pins 1 & 2 bridged with solder.]] 
If the volume pot on your system 4 or later sound board fails or otherwise needs replacement, it's often difficult (or impossible) to find a direct matching part. In such cases adding a remote volume pot may be the only solution. 

The first thing to do is flip the board over and make sure that somebody hasn't bridged pins 1 and 2 of connector 10J4, as shown here. If it has been bridged, remove the solder bridge and solder the pins independently to the board. 

[[File:DSC0762.jpg|300px|thumb|left|Taking a reading across volume pot legs.]]
[[File:DSC0763.jpg|300px|thumb|right|Taking a reading across volume pot legs.]] 
Take a resistance reading across the existing volume potentiometer's legs. If you get a reading above 4K ohms, the potentiometer is not mostly shorted and will not require its leg to be cut as detailed below. (i.e. you may skip that step below.) 

This potentiometer is not mostly shorted and could be left un-cut. 

[[File:DSC0764.jpg|300px|thumb|left|Cutting the volume pot's left leg.]]
[[File:DSC0765.jpg|300px|thumb|right|After cutting volume pot's left leg.]] 
If the previous resistance reading reads less than 4K ohms, then one leg of the potentiometer '''must''' be cut. (This one was cut for the sake of demonstration.) 

After the cut, the potentiometer should look similar to this. 

[[File:DSC0766.jpg|300px|thumb|left|Jumper added across volume pot legs.]]
[[File:DSC0767.jpg|300px|thumb|right|Replacement potentiometer.]] 
'''In all cases, a jumper must be added to the back side of the board to bypass what is left of the old potentiometer.''' 

A new 5k-ohm, audio (logarithmic) taper potentiometer must be sourced. 

[[File:DSC0768.jpg|300px|thumb|left|Wiring of new potentiometer.]]
[[File:DSC0769.jpg|300px|thumb|right|Wiring of 10P4.]] 
Here a radio shack 271-1720 potentiometer was used. 

Three wires must be run between the potentiometer and 10P4, the plug that connects to 10J4. The wires must then be connected to 10P4, as shown. 

Plug the new 10P4 into 10J4, and the on-board volume pot will be bypassed with the new external pot. 

===If All Else Fails===
You can source a replacement sound/speech board. It may be more cost effective than sending out your sound boards to be fixed, especially as you may be able to sell the original boards to get back some of the initial outlay. These are good quality products, the price isn't bad and they should last for many years to come. James Kohout's [http://www.pinballpcb.com pinballpcb.com]

==Solenoid Problems==

===Controlled Solenoids===
[[File:WMSPharoahExtraGround.jpg|300px|thumb|left|In addition to the ground braid being screwed to this post, a white wire with red stripe is also connected.]] 
Some Williams games provide ground for coils via an extra wire (white/red) that must be connected to the backbox ground stud as shown in the picture at left. If this wire is not connected, some coils will not work. An example is Pharaoh, which uses this path to ground for both "Magna Save" magnets and the hidden tomb coils.

Note: in the example picture, a nut has been used to replace the typical "wing nut".
 

====Special Note Regarding Coin Lockout Coil and Free Play====
When some games (perhaps all games but at least Flash using Green ROMs) are set on "free play", by setting adjustment 18 to zero, the coin lockout coil will not be turned on. This makes sense since when free play is enabled, coins should drop straight through the coin mech and into the coin return.
 

===Special Solenoids===
[[File:WMSSystem3-7SpecialSolenoidDrives.jpg ‎||left||thumb||300px||A closeup of the special solenoid circuitry showing transistors Q2 through Q12. Note that these transistors are not numbered row and column sequentially. Argh!]]
[[File:WMS3-7SpecialSolenoidDiagram.jpg ‎||right||thumb||300px||Diagram of Williams System 3-7 Driver Board Special Solenoid Section]] 
The Special Solenoid drives switch power to ground for pop bumpers and sling shots. This "special" circuitry was implemented with the thought that the switch matrix could not be polled rapidly enough for these devices to be highly responsive. The drive transistors can be switched on either by a switch closure on the device, or under software control by the CPU.

The Special Solenoid drive transistors, Q2 through Q12, are located just above the flipper power ground enable relay Z1.

The flaw in this circuitry is that a "one shot" was not implemented (ala Gottlieb System 80 Pop Bumper Driver Boards). One shot circuitry only allows the associated solenoid to engage once per switch closure. In the case of the Williams special solenoids, as long as the switch is tied to ground, the solenoid will be engaged. As long as a device switch (pop bumper or sling) is closed, then coil power will be switched to ground continuously, eventually overheating and killing the associated TIP-122 (or TIP-102) transistor and / or the solenoid.

There is also a lack of "intelligence" in the software as was implemented eventually in WPC games. WPC games disable a device if the device's associated switch is sensed closed 10 times in succession without sensing any other switch closure.
 

====Wetting Current Resistor/Capacitor for Special Solenoids====
[[File:System4SpoonSwitch.jpg ‎||left||thumb||300px||A resistor/capacitor connected across a pop bumper spoon switch.]]
[[File:RCNetworkSystem4.jpg ‎||right||thumb||300px||The schematic for the circuit as implemented for slingshot switches.]] 
Williams used a 22uf capacitor and a 100ohm resistor, themselves connected in series, wired across special solenoid switches to provide a minimum "wetting current" across the switch contacts. This implementation also provides some measure of "electrical debouncing" of the switch. In the image at left, the black wire is coil power from the power supply. The orange wire is the path back to ground via a driver board special solenoid drive transistor. The green and white wires are switch matrix wires for the "scoring switch". A 1N4004 switch isolation diode is used just like any other switch matrix switch.
 
See: https://en.wikipedia.org/wiki/Wetting_current

The special solenoid switch contacts are pulled high to 5 VDC through a 4.7K ohm resistor on the driver board. When the special solenoid switch closes, this voltage is shunted to ground resulting in a current through the contacts of approximately 1 mA. This very low "wetting current" is insufficient to keep the contact surfaces clean and free from dirt and oxides. An RC network is placed across the contacts to increase the wetting current and help break through any dirt or oxidation that has formed on the contact surfaces. When the contacts are open, the capacitor charges to 5 VDC through the 4.7K and 100 ohm resistors in series. When the contacts close, the capacitor discharges through the contacts and the 100 ohm resistor, resulting in a momentary peak current of approximately 50 mA. This discharge wetting current is sufficient to burn off any surface film that has built up on the contacts. Once the contacts open again, the capacitor begins charging again and effectively extending the contact closure time. This also provides some amount of electrical debouncing.

 

==Lamp Problems==

===General Illumination Lamps===

[[File:WMSSystem7PowerSupplyBurn.jpg||left||thumb||300px||An extreme example of high current damage to the general illumination traces of a System 7 power supply.]] 
One of the largest weaknesses of the System 7 board set (starting with the later run of Black Knight) is the general illumination PCB connection. The configuration of that connection evolved from a two pin Molex connector into four (two for AC in, two for AC return) 18 gauge wires soldered directly to the board and connected to the transformer secondary with a 4-pin Molex connector.
 

===Controlled Lamps (Lamp Matrix)===

One source of problems with the lamp matrix can be the 27 ohm 3 watt resistors used for the lamp columns. These resistors put out a '''ton''' of heat! In some extreme instances, they can get so hot that they will literally melt the solder which holds them to the driver board, and fail off the board. It is best to replace these resistors with 27 ohm 5 watt resistors. The 5 watt variants can dissipate the heat a little better. When replacing these resistors, make certain to allow enough space under them to allow for air cooling. Even though it is best to use higher wattage resistors, they still put out a fair amount of heat.

<center>
<gallery widths=200px heights=350px perrow=4 caption="Williams System 3-7 Driver Board Lamp Matrix Resistors">
File:Wmsdriver_heatdamagedresistors.jpg|<center>Old resistors in questionable condition due to overheating. Note these are 3 watt resistors as shipped by WMS. Later boards used 5 watt versions.</center>
File:Spacer WMS Lamp Resistors.JPG|<center>Using a pencil to allow proper spacing of the resistors from the driver board. One by one, place the legs of the resistors through the circuit board, and bend the legs over.</center>
File:Spacer WMS Lamp Resistors Back.JPG|<center>Flip the board over, and allow the resistors to "hang" off the board.</center>
File:Spacer WMS Lamp Resistors After.JPG|<center>New resistors soldered on the board with ample air flow beneath them.</center>
File:ResistorRaising.jpg|<center>Another method of raising the resistors. Be sure to remove the cardboard when complete.</center>
File:WMSSystem3-7LampMatrixResistorsRaised.jpg|<center>Side view of resistors raised with ample air flow beneath them.</center>
</gallery>
</center>
 
====Testing the Lamp Matrix====

This is a generic [[media:13-lampwiring.pdf|Lamp Matrix Diagram]] which you can refer to for testing the lamp matrix.

====Reducing heat by replacing the TIP-42 lamp drive transistors and eliminating the 27 ohm current limiting resistors====

The original Williams (and Data East) lamp matrix circuitry dissipates a lot of heat through the 27 ohm current limiting resistors. Often, this part of the circuit board is badly heat damaged. The TIP42 transistors are bipolar PNP transistors, and require a lot of drive current on the base. The current through the 27 ohm resistors does not even go to lamps, just to the base. The issue starts when the 40 pin interface connector becomes faulty. If the lamp scan update is not received by the driver board, it will sit on one selected column of lamps.. and promptly burn one 27 ohm resistor off the board, possibly burning a hole in the board.

The first method below is simpler to implement, but the second method is included, as it has been implemented for many years.

In the first upgrade method, replace the 8 TIP42 transistors with the darlington version, which require much less current. Get 8 TIP125 transistors, and replace the 8 original transistors, being careful to keep them oriented the same way. Masking tape can keep all 8 lined up while soldering. The second step is to remove all 8 of the 27 ohm resistors, and replace them with 10K 1/4W resistors.

The second method uses modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06).

Once MOSFETs are substituted for the TIPs in the lamp driver circuit, it is possible to replace the 27 ohm resistors with simple jumpers or even leave the 27 ohm resistors in place if they are in good shape as the low resistance will have a negligible effect on the operation of the MOSFET. However, the problem with either of these is that the MOSFETs are driven by 18 VDC Source to Gate voltage which is dangerously close to the absolute maximum rating of the IRF9530 and IRF9Z34 of 20 VDC (this also holds true for Data East MPUs). The FQP17P06 has a higher Vgs rating (25VDC) than either the IRF9530 or IRF9Z34N - but you are still driving the part at over 70% of its absolute maximum. Typical uses for these MOSFETs drive them by about 10 VDC Source to Gate voltage (or -10V for P-Channel MOSFET's used here).

By using a "Voltage Divider" circuit with two 1K, 1/4 watt resistors to divide the source 18 VDC in half, the MOSFET will be driven with 9 VDC Vgs.

[[File:WMS_Sys3-7_Lamp_FETs_Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys3-7 Lamp FETs Back.jpg|300px|right|thumb|1K resistors installed on the solder side of the board.]]
Parts Required
*8 P-Channel MOSFETs (IRF9530, IRF9Z34N or FQP17P06)
*16 1K Ohm 1/4 Watt resistors

Procedure
*Remove the TIP-42 transistors Q63, Q65, Q67, Q69, Q71, Q73, Q75, Q77
*Remove the 27 Ohm resistors R149-R156
*Remove the 2.2K ohm resistors R141-R148
*In place of the 27 Ohm resistors, install 1K Ohm resistors
*In place of the TIP 42 transistors, install the P-Channel MOSFETs, oriented the same as the TIP-42s were oriented
*On the solder side of the board, install eight 1K Ohm resistors between the MOSFET gate and the 18VDC source.
 

[[File:System3-7FETs.jpg|300px|left|thumb|Another implementation of 1K resistors installed on the component side of the board.]]
[[File:WMS_Sys3-7_1K_Resistor_Lamp_FETs_Back.jpg|300px|right|thumb|Closeup of 1 kohm resistors added to solder side of board]] 
Pay close attention when adding the 1 Kohm resistors to the solder side of the driver board on heavily burnt / delaminated boards. The resistor leg and / or the end of resistor leg comes within close proximity of the same column or adjacent column traces.
 

[[File:WMS3-7DriverFETModAlternate.jpg ‎|300px|left|thumb|Another implementation of 1K resistors installed on the solder side of the board. This implementation requires less resistor leg bending and hence, a much easier install.]]
[[File:WMS3-7FETFrontSideOnlyMod.jpg ‎|300px|right|thumb|A "component side only" implementation. Image courtesy of Victor, Pinsider "DumbAss".]] 
Yet more ways to efficiently add the voltage dividing resistors.
 

==Flash Lamp Problems==

System 3-7 flash lamps (and System 9/11 also) are driven by the same kind of circuitry that drives solenoids. Flashers are generally wired two in series (like old Christmas lights). If one lamp fails, the neither lamp will light. They are wired in series so that they split the DC voltage across two lamps, preventing them from burning out quickly.

To make the flashlamps "agile" (i.e. turn on rapidly) and to extend the life of the flashlamps, a "warming" circuit was employed which connects two series flashlamps to coil power via a 330 ohm 1 watt resistor. This causes the lamp filament to turn on very slightly, and to "warm up", ready for the power to find ground via a 1 ohm (5 ohm in System 11) resistor.

Over the years, these games have undergone "maintenance" to replace parts on the resistor board and have sometimes also been rewired, attaching the wires to different solder lugs on the flashlamp warming board.

Note: If LED flash lamps are installed instead of incandescent lamps, the 330 ohm warming resistor must be removed from the circuit. If it's not removed the lamp will remain on, albeit not at full intensity.

<center>
<gallery widths=300px heights=300px perrow=2 caption="Williams System 3-7 (and 11) Warming Board Implementation">
File:FPWarming.jpg|<center>Firepower warming board. The 330ohm resistor has clearly failed. This board is connected to the game wiring differently than Gorgar and is not factory, yet it works. The red wires are power. It's difficult to see in this pic but a yellow wire is also connected to the red wires. That yellow wire connects to two flashlamps in series. The other yellow wire returns from those flashlamps and is connected to the 1ohm and 330ohm resistors. Power finds ground through the 330ohm resistor and the black wire. This forms the "warming circuit". Power also finds ground through the 1ohm resistor, the brown/violet wire and the driver board drive transistor.</center>
File:FirePowerWarmingBoard.jpg|<center>Firepower warming board. The 330ohm resistor has been replaced. This board is also connected to the game wiring differently than Gorgar and is not factory, yet it works. The two yellow wires connect to two flashlamps in series. Red is flashlamp power. Black is ground. The remaining wire is a path to ground via the drive transistor.</center>
File:GorgarWarmingBoard.jpg|<center>Gorgar warming board. The two yellow wires connect to two flashlamps in series. Red is flashlamp power. Black is ground. The remaining brown/violet wire is a path to ground via the drive transistor. This warming board wiring matches the schematics and corresponds to factory wiring.</center>
File:System11WarmingBoard.jpg|<center>System 11 (High Speed) warming board. Note that flashlamp power is no longer routed through this board. The orange wire connects to two flash lamps in series which are then connected directly to flashlamp power. The two black wires are ground. The gray-blue wire is the path to ground via a drive transistor.</center>
</gallery>
</center>
 

[[File:WarmingResistorSchematic.jpg|300px|thumb|left|Warming Resistor circuit shown in Stellar Wars schematics. Note the two #89 lamps wired in series. They are dimly lit with power from the red wire, through the 1 ohm resistor, through the lamps, through the 330 ohm resistor, and then to ground. They will fully light when the drive transistor that services the GRY-BLK wire is switched on, providing a low resistance path to ground and effectively removing the 330 ohm resistor from the circuit.]] 
The diagram at left shows the physical connections to be made by the warming board. The schematic snippet at right is from Stellar Wars (System 4) and accurately depicts connections. The schematic contained in Gorgar is not correct for this circuit. Warming boards are not shown in any of the System 11 documentation.
 

==Switch Problems==
WARNINGS: 
*Never use a file, sandpaper, or anything more abrasive than an old business card to clean gold flashed switches. Doing so will remove the gold flashing and permanently ruin the switch.
*Never adjust switches with the game powered on. It is far too easy to short the switch, or your adjustment tool, to adjacent power (lamps or solenoids) and damage the switch matrix circuitry on the driver board.

The only switches that can be filed are tungsten switches which are both materially and physically quite different from gold flashed switches. In a System 3-7 game, the only tungsten switches are the cabinet flipper buttons and the flipper mechanism end-of-stroke switches.

Tungsten cabinet flipper switches and end-of-stroke switches "arc" and will become blackened (or whitened) and pitted over time. Once this happens, the resistance between the switch pair increases, which reduces electric current, which reduces coil power, which reduces flipper strength.

Switches vary from game to game, most are standard for WMS System 3-7.

A few of the common switches are listed here:
{| class="wikitable"
!colspan="2" |System 3-7 Switches
|-
!Part Number
!Common use
|-
|SW-1A-118 || Spinner Blade switch
|-
| SW-1A-124 || Rollover Lanes (inlanes/outlanes as well)
|-
| SW-1A-130-1 || Switch Rightmost on Ball Runway (Ball Locks, with round white nylon piece on leaf end)
|-
| SW-1A-136 || 2nd Ball Runway Switch (typical, depending on game)
|-
| SW-1A-137 || 3rd Ball Runway Switch (typical, depending on game)
|-
| SW-1A-138 || Shooter Lane Switch
|-
| SW-1A-139 || Lane Change Switch (can use SW-1A-150, usually stacked to right flipper or right EOS)
|}

These were used throughout the Williams games:
Examples are for the above include System 3, System 4 (Flash), System 6(a) (Firepower and Alien Poker), System 7 (Black Knight). Some appear on F-14 Tomcat (’87) and further, even after most Ball Ramp switches had changed over to micro switches. Black knight also used micro switch kits, which Williams provided as a field replacement kit for operators. Drop Targets also had factory micro-switch adapters fitted later to make them more reliable.

'''''Switch Assembly Note''''': The Williams factory (or more accurately their suppliers) assembled many switches so one of the blades was facing the wrong way. It should have two gold contacts facing each other, where in fact one blade faces so that the rough-sided rivet is making contact. If you have an intermittent switch, it can be worth the time to de-solder it and remove from the game and then carefully pry the switch stack apart and reassemble the switch so the gold contacts face toward each other. Keep the exact order of spacers and just reverse the one blade. While there, carefully clean the switch contacts with naptha and a clean cloth. Again, please don't use emery (or files) on these switch points! Once the gold has worn, they form "dead spots" and won't work reliably. Another symptom of the misassembled switch stacks is multiple switch closures.

===How the Switch Matrix Works===

First of all, a switch is usually an electro-mechanical device with moving parts. This includes leaf blade switches, tilt switches (where the ring is fixed and the plumb bob is the moving part of the switch) and micro-switches. When a mechanical switch closes the contacts tend to oscillate before coming to rest. It literally 'bounces' several times before remaining closed.

The CPU could see the rapid open/close events as multiple switch closures, so there is usually some 'debounce logic' built into switch matrix reading programs. The CPU sees a switch closure and then 'checks back' to see if it remained closed as few milliseconds later. If it is closed, the CPU processes the event once, scoring the correct value or in some cases triggering a solenoid to fire. In the case of Williams 3-7 games, the switch debouncing for normal switches is done at the software level; unlike other contemporary manufacturers' method, Williams' software is more sophisticated in that the definition of switches include the ability to treat a switch as fast-response (example: spinner switch), normal response (lane rollovers - longer 'ignore time' to prevent duplicate reads on a slow traveling ball), and the longest time (trough switches - where the ball would travel over the first 2 switches on a multiball machine, you would not want those to react unless a ball were truly in the trough).

As an aside, an optical switch (or opto) has no moving parts and so doesn't suffer from mechanical switch 'bounce'. (An optical switch can suffer from electronic switch bounce - many rapid activations per second - which is why they usually utilize circuitry known as a Schmitt Trigger to lower the probability of debounce errors). It also shouldn't need adjustment or in theory wear out as quickly as say a micro-switch. However, an opto needs additional circuits and is not as simple to work on or replace as other switch types. Although you can not see an infrared transmitter with you naked eye, you can look at it with a digital camera. Optos were never used in System 3-7 games, although they were engineered and prototyped just at the end of System 7.

Wiring up every switch separately with multiple wires running to the backbox would be expensive in the amount of wiring and in the number of inputs required to the game's logic. Rather than do that, the engineers designed a switch matrix with 8 column wires and 8 row wires, creating a 'matrix' of 8x8 giving a total of 64 possible switches. Not all of these switch positions are used.

The first column of the switch matrix (COL 1) is dedicated to the same switches on the System 3-7 games. You can check in a manual, but these will be the cabinet tilts, the coin switches which sense coin drops, the credit button (to start a game) and the high score reset which is also in the cabinet (on the coin door). In order from row 1 through row 8, they are the plumb bob tilt, ball roll tilt, credit button, right coin chute, center coin chute, left coin chute, slam tilt, and high score reset button.

For the most part other switches will be on the playfield (exceptions could be a lane change or magnasave button/switch).

So how is the switch matrix read by the MPU? It uses the most useful Peripheral I/O device in this pinball era, the Motorola 6821 PIA (earlier this was the MC6820 PIA).

The 6821 is made up of two 8 bit ports, one port is known as 'Port A' and the other 'Port B'. Any of the 16 pins can be configured as inputs or outputs. That's exactly what's needed to drive our Switch Matrix! An 8-way output port B to 'send' (or strobe) down the Columns to the switches, and an 8-way input port A to 'read' the Rows from the switches. The Columns are known commonly as 'Drives' or 'Strobes' and the Rows are known as 'Returns' for this reason. In a similar way (an 8x8 matrix) another PIA is used for the Lamp Matrix.

The switch matrix PIA is at IC11 on the Driver Board (also called PIA II). This PIA doesn't drive the switch matrix directly from it's TTL output pins. There are +5v powered 'pull-up' resistors and 4 IC's which act as drivers/buffers helping to protect the PIA from damage if the switch matrix is shorted.

;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.
:A 7406 or 74LS06 will work and are common parts.
;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.
:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 14-leg DIP will work.
:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''

The CPU writes to the output port of the PIA driving column 1, then the return input port is saved, holding the status of all 8 rows in one byte. The program then 'looks' at each of the rows 1-8 in quick succession. It checks to see if the signal is getting through on the row that's currently being read. Think of it as an 8 bit answer for that column showing which switches in that column are closed. Say 00010001 returned would mean switches at C1,R4 and C1,R8 are closed.

So for every 'drive' down a column, the machine does 8 'reads' of the rows. Then the CPU moves on and drives column 2, looking again at each of the rows 1-8. It continues through all of the remaining columns in this way. This is done very rapidly by the CPU, strobing the whole matrix looping over and over many times a second. Because it's so fast, even multiple switch closures are rarely missed, in fact as mentioned above it has to debounce the results to obtain an accurate result. Williams' operating system software on machines from at least system 6 up through system 11 have differing debounce values depending on the type of switch, allowing greater sensitivity on certain types of switches, and desensitizing others (such as lock or trough switches).

The diodes on every switch help to steer the drives only to the row that's being read and not back into other parts of the matrix. That's why good diodes on switches are so important, as they must only allow current to flow in one direction: '''''from''''' column '''''to''''' row. Essentially that's how the switch matrix reads switch closures.

This [https://www.flippers.be/basics/101_switch_matrix.html article] by Aeneas describing a later game's switch matrix may be useful as a different explanation with a diagram. Transistors can be used on the drives (as with modern games like DE or Stern ), different buffer chips can be used, but the basic switch matrix design hasn't changed over the years.

Finally a warning about protecting the switch matrix.
Please note that '''''nothing''''' will protect the switch matrix IC's and PIA if (for example) the +50v solenoid voltage is shorted into the matrix. This happens if the 'lane change' switch is attached in a stack on the flipper mech and shorted to the EOS switch. In later designs the 'lane change' was moved to be stacked with the flipper buttons (nearly as bad) or to a separate button which was a better design. Be very careful if working under the playfield '''not to short the solenoid or lamp power into a switch'''. It can be a lot of work to repair the damage done to the driver board, so be careful with you screwdriver and loose solenoid power wiring. Most people who have been repairing games long enough learned the hard way, and won't work under the playfield with the power on.

===Special Switches===
There are a few switches that are dedicated, and not part of the switch matrix. The coin door Advance and Auto/Up Manual/Down switches, which let you start diagnostic tests when the switch matrix is faulty. 

Also, there are a maximum of 6 special solenoid switches, which directly connect to the solenoid logic on the driver board. When Williams first designed these games, they were worried that the CPU couldn't always 'keep up' with the ball hits to the pop bumpers or slingshots. So during game play the switches on the playfield fire the special solenoids directly from the playfield. These usually include the spoon switches on the pop bumpers and slingshot stand-up switches.

There is a 22uF capacitor and a 100 ohm resistor mounted across the special solenoid switches. The use of the capacitor and resistor creates what is called an [http://en.wikipedia.org/wiki/RC_circuit RC circuit]. The RC circuit is used to filter noise from the switch signal as well as to ensure a minimum pulse length for the solenoid activation. If using a polarized capacitor the positive terminal goes to the tie point with one end of the resistor attached. Should a special solenoid lock on, and the switch leaves are properly gapped, the issue may be a shorted switch capacitor or resistor.

All pop bumpers and slingshots have a secondary switch which is part of the switch matrix. It closes when the coil is fired and tells the CPU to increment scoring and in some cases to trigger sounds for these devices. The scoring switch is mechanically closed, by the 'elbow' of the slingshot arm or by the bakelite yoke connected to the pop bumper ring.

Confusingly, the CPU can also fire the 6 special switches from PIA lines for the diagnostic tests, but these PIA signals are never used during game play. If all these solenoids work during diagnostic tests, but not in game play it points to the switch inputs or the 7408s at IC6/7. It won't be the 7402s at IC8/9.

I have seen a game that worked in play perfectly, but the diagnostics could not fire two of the pop bumper solenoids during tests. This was a Switch Matrix PIA with faulty output at pins 19 (CB2) and 39 (CA2), other than that the PIA was working correctly and so it could still be used to drive the Switch Matrix. If a switch row or column went out, the PIA would then have to be replaced.

: '''Here is a list of the PIAs and where the pins are that fire the 'special solenoids' during diagnostics:'''
{| class="wikitable"
!colspan="5" |Special Solenoid Diag. PIAs
|-
!ST#
!PIA
!CHIP
!Pin #
!Location / Board
|-
|1 ||III ||IC10 Lamps ||19 ||Middle PIA on Driver Board
|-
|2 ||III ||IC10 Lamps ||39 ||Middle PIA on Driver Board
|-
|3 ||II ||IC11 SW Matrix ||19 ||Left PIA on Driver Board
|-
|4 ||II ||IC11 SW Matrix ||39 ||Left PIA on Driver Board
|-
|5 ||IV ||IC 5 Solenoids ||39 ||Right PIA on Driver Board
|-
|6 ||I ||IC18 Displays ||19 ||Via 1J1-26 on CPU Board
|}

===Testing the Switch Matrix===
To test the switch matrix in the game, first remove both Switch Matrix connectors on the top right of the driver board. J2 is Column (green wires) and J3 is Row (white wires). Then run a switch test from diagnostics, you should get no switches being sensed.

Use an alligator test lead as follows:
* Connect one end of the test lead's alligator clip to the column pin, starting at column 1. That's the bottom pin of J2.
* Then use the other end of the test lead to touch the appropriate row pins.
* Start at the bottom pin of J3, which is row 1. You should see switch #1 indicated (R1C1).
* Move the probe to the next pin up on J3, which is row #2. You should see switch #2 indicated (R2C1).
* When you got to the top of the row pins, move the clip end to COL #2 (up one pin) and start again with row #1.
* Activate each switch in turn by connecting the appropriate 2 male pins on the CPU board with your test lead.

Using your switch matrix chart from the manual as a guide, you may find the faults as your game "sees" on the same switches.

If you get an error in sequence, more than one switch registers at a time or you are missing a row or column - then you '''know the problem must be on the MPU board'''. You can either try to fix it or send the board out for repair.

If the above test works correctly, meaning all switches register correctly then your problem must be the wiring or on the playfield.

===Testing the Switch Matrix PIA===
No section on the switch matrix is complete without mentioning the switch PIA. That IC and 4 buffer IC's are the only logic in the switch matrix. The complete instructions for testing all the PIAs are beyond the scope of this section.

The only sure-fire way to test the PIA is with the 'Leon Borre test ROM' in the MPU board. You do this by taking the MPU and Driver boards out of the game and putting them on the bench. This will also let you trace back through the circuit to find a fault more easily, and it's not as hard as you may think. It will also exercise the CPU memory and test all the PIAs on the Driver Board, not just the switch matrix PIA. Here are his excellent instructions:

[[Leon_Borre_Repairing_Williams_System_3-6_CPU_Boards | Leon's Repair Pages for WMS System 3-6 games]] including a free test ROM.

[[Leon_Borre_WMS_System_7_Repair | Leon's Repair Pages for WMS System 7 games]] including a free test ROM.

These Belgium guys are knowledgeable about pinball.

Should any of the chips in the switch matrix prove to be faulty, be particularly cautious in replacing them. They have a greater than usual tendency for lifted traces and pads when desoldering. Heat rising from the lamp matrix resistors has a tendency to not only cause these chips to fail, but also to loosen the bond between the circuit board and the solder pads and traces on this area of the driver board.

===Switch Matrix Components===
Final thoughts about components which make up the switch matrix.

The passive components:
On the driver board there is an RC network, made up of 16 x 4.7K pull-up resistors that you can measure with a DMM. Tolerance is not critical, but should measure between 4.5K to 5K which is about a +/- 5% range.
There are also 16 x capacitors (470pF at 50v, ceramic) these should not measure as a short, if in doubt just replace them.
And 8 x 1K ohm resistors at the switch inputs (rows) at R196-R203 these can not be open or shorted and must be around 1K each.

You can see the above chips inverting signals with the game running and a logic probe. Check if signals look weak or suspect. If you see a signal on the input side and then nothing inverted on the output side, then that's your problem.

{| class="wikitable"
!colspan="4" |Beyond that IC15-18, which are the Switch Matrix inverting buffer / drivers:
|-
!IC Location
!Inverting Pairs. Leg a to b listed as a,b
!Switch Row/Col Numbers
!IC Part Number /Eqivalent
|-
|IC15 ||3,2 7,6 14,15 9,10 in that order ||Rows 1-4 ||(MC)14049U / 4049U
|-
|IC16 ||3,2 7,6 14,15 9,10 in that order ||Rows 5-8 ||(MC)14049U / 4049U
|-
|IC17 ||2,1 6,5 12,13 8,9 in that order ||Columns 1-4 ||7406(S) / 74LS06
|-
|IC18 ||2,1 6,5 12,13 8,9 in that order ||Columns 5-8 ||7406(S) / 74LS06
|}

{| class="wikitable"
!colspan="5" |J2 (Column) and J3 (Row) connector pins:
:
|-
!Connector
!Male connector Pins
!Switch Row/Col Numbers
!IC Location
!IC Part Number /Eqivalent
|-
|2J2 ||pins 1-3 and pin 5 ||Columns 5-8 ||IC18 ||7406(S) / 74LS06
|-
|2J2 ||pins 9-6 ||Columns 1-4 ||IC17 ||(MC)14049U / 4049U
|-
|2J3 ||pin 1 and pins 3-5 ||Rows 5-8 ||IC16 ||(MC)14049U / 4049U
|-
|2J3 ||pins 9-6 ||Rows 1-4 ||IC15 ||(MC)14049U / 4049U

|}

Except for the 6821 PIA which is getting harder to find, all the switch matrix components are readily available.
However there are acceptable substitutes on the market. Any of the following part numbers are drop-in replacements for the 6821.
68A21, 68B21, 6521, W65C21N.

===Wire Jumpers on System 7 Driver Boards===
[[File:ZeroOhmJumpersS3-7.jpg ‎|300px|left|thumb|A Williams System 3-7 Driver Board, retrofitted with wire jumpers at R04-R211]]
Williams removed some resistors from the switch matrix inputs and used wire jumpers instead. This happened from the start of System 7. The first thing to do with a driver board (which may not be from that game) is to measure these resistors and make sure you have the the driver board set up for the correct game. '''''While a board with wire jumpers can be used in System 4-6 games, using a board with resistors in a System 7 game will cause problems.''''' Replacing the 330 ohm resistors with wire jumpers helps with switch sensitivity and with sensing more than one switch closure at the same time.

On driver boards from Black Knight and later System 7 games, there should be 8 wire jumpers (or zero ohm resistors) used on the switch matrix at positions W9-W16. These are located on the upper right hand corner of the Driver Board just to the left of J2, the top right connector which is the switch matrix column drive. To the left are two columns of 7 resistors each, the second column should be the wire jumpers, along with the top position of the next column to the left (column with 2 resistors only).

System 4-6 Driver boards, (games like Alien Poker, Firepower and earlier SS games) were released with 330 ohm resistors (orange, orange, brown) in these 8 locations. Starting with Black Knight and later (System 7 games) they are called R204-R211, and are zero ohm resistors (usually a tan body with one black stripe). You can replace or jumper over them with wire leaving the resistors in place. In all other aspects the driver boards are identical, so it's easy to convert between the two. This is why they are usually known as ''System 3-7 driver boards''.

Before you start to replace parts on the driver board, be sure your playfield switches are working and the diodes are good. You need to unsolder one end of the diode from the switch to be able to test it correctly with a DMM on the diode setting. While you are there, clean the switch with a business card soaked in naptha or contact cleaner sprayed on the business card (with the game off, contact cleaner is flammable!) See if any blackness comes off on the card. You can also gently wipe the contacts until shiny with a Q-tip or the corner of a clean rag dipped in isopropyl alcohol. A pencil eraser also works well to clean switch contacts.

=Game Specific Problems and Fixes=
==Black Knight==
===Magna Save Performance===
There are 2 under playfield relays used to shunt high voltage to the magna saves. These are high voltage contacts and should be filed for maximum conductivity and power for the magnets.

===Magna Save Magnets Not Working===
If the magnets are not working in test or game, make certain that the white-red wire is tied to the ground screw in the backbox. This white-red wire is fed from the relay coils, which enables each appropriate magnets.
===Fast moving ball flies through upper lock===
Mount a shooter lane bracket underneath the plastic of the upper ball lock trough. With creative bending, all ball motion will stop on entering the trough. The ball will drop down ensuring credit is awarded for the lock.

===Ball Lock Scoring Bug===
There is a software bug in version L-3 and L-4 where instead of getting 5000 points with other balls in the lock you get 10,000, scored in increments of 5000. There is no current fix for this; it may have been intentional for the additional score (usually picked up by another player) but probably an oversight by the original programmer. There is a footnote in the operator's manual referencing this. It is unknown what the original intention was.

===Right Ramp Gate Adjustment===
It is erroneous to have the mystery rollunder gate score in one direction only; the switch should activate both going UP to the upper playfield as well as DOWN to the lower playfield. It can be a strategy in multiball to let it roll down the switch, multiplying the mystery value.

==Firepower==
===Firepower Won't Start a Game===
Firepower and other multi-ball games are infamous for being stubborn if there aren't three balls in the trough, or if one of the trough switches isn't closed. Additionally, multiball games usually have a shooter lane switch. If MORE than 3 switches are closed, the game will also not start.

My Firepower, in particular, is frequently upset if the right-most switch isn't closed, and that switch has an unusual actuator on it that doesn't work as well as a common rollover actuator. That switch is a little mangled, so it's the one that is most problematic. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 18:12, 21 May 2014 (CDT)

==Time Warp==
===Time Warp loses background sound occasionally===
There is a software bug in Time Warp where the background sound (if enabled) will go mute at ball launch. This happens whenever the ball kicker launches twice, or when a ball drains without scoring any points. There is a fix for this identified as Time Warp L-3 however it is not officially sanctioned by Williams and so is not readily available.

=Parts Substitutions & Replacements=
==Boards==
* Displays
** [http://xpinpinball.com/product-category/xpin-displays/ XPin]
** [http://www.rottendog.us/?product=dis326 Rottendog 6-Digit]
** [http://www.rottendog.us/?product=dis079 Rottendog 7-Digit]
* MPU
** [http://www.rottendog.us/?product=mpu327 Rottendog] (no longer supports System 7 games)
* Power Supply
** [http://www.rottendog.us/?product=wdp3211a Rottendog]
** [http://xpinpinball.com/product/xp-wms8345/ XPin]

NOTE: [http://pinballpcb.com/ Kohout Enterprises] has begun manufacturing circuit boards again.

=Repair Logs=
Did you do a repair? Log it here as a possible solution for others.

==Unreliable +5V==
A Firepower won't boot consistently. It was reliable before it was moved in a box truck. +5V supply measures low. For some reason, I decided the problem had to be the diodes in the power supply and replaced them, which didn't help. I replaced the +5V cap in the power supply, C16, and all was well. (Thirty year old filter caps are all absolutely suspect.)

Once I had the cap loose, I discovered I could shake it and hear it rattling inside. Presumably, the jelly roll of electrolytic was dried out. Shaking it might have the internal components in the right place, but probably not. A few miles in the back of the truck was enough to wreck it, more permanently before. The game has been very well-behaved since replacing the cap with a new one. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 18:12, 21 May 2014 (CDT)

==Unreliable +5V, part 2==
All classic pinball boards rely on 5V logic. Most data sheets indicate 5V, +/- 0.25V. Always check the 5V on the power supply, AND on the MPU board. Note that there may be 5.2V on the power supply, but 4.8V on the MPU. This is too low.. small pulses can pull the 4.8 below 4.75 fairly easily and cause resets. If there is less than 5V on the MPU board, but the voltage is right on the supply, try checking voltage drops at each individual connector pin. One will usually find that pins will have built up tarnish, or heat has turned them grey or brown.. this is the tip off that the connector needs to be replaced. I know, groan.. it can be a pain, but replace the header in the circuit board. Make sure to remove or clip the key pin. Then replace the connector on the wires (female) with crimp and poke type. Use a ratchet crimper, and tug on them after each crimp to prove that they are good. Replace the wires one by one.. clip, crimp, poke.. copy each wire position from the original one one at a time, and keep in mind that the connectors have a ramp and go on one way. Replace and power up, and then go back to the meter, and verify that the voltage on the MPU board has risen..

==CPU will not start==
This happens to involve a Type 2 sound board, but it could apply to an MPU board or a Type 1 sound board. The reset pin voltage (CPU Pin 40) was low and would slowly climb after power on, but not enough to allow the CPU to start. All components in the reset section were good, and replacement parts did not make any difference. The problem was the sound board's PIA. Its reset line was pulling down the voltage so much that the CPU would not start. After replacing the PIA, the sound board booted and worked fine.

Sega/Stern White Star Repair

2023-03-20T21:40:57Z

Jimpal: /* Service Bulletins */

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

==Introduction==

 

==Games==
===Sega===
*Apollo 13
*Goldeneye
*Twister
*Independence Day
*[[Space Jam]]
*Star Wars Trilogy
*The Lost World Jurassic Park
*The X Files
*[[Starship Troopers]]
*Viper Night Driving
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park

===Stern===
*Striker Xtreme
*[[Sharkey's Shootout]]
*High Roller Casino
*Austin Powers
*[[Monopoly]]
*NFL
*Playboy
*Roller Coaster Tycoon
*[[The Simpsons Pinball Party]]
*Terminator 3: Rise Of The Machines
*The Lord Of The Rings
*Ripley's Believe It Or Not
*Elvis
*Grand Prix
*The Sopranos
*NASCAR

==Recommended Documentation==
===Manuals===
The owner's game manual is a handy resource to have for general game operation, game settings & diagnostics, switch & lamp matrices, fuse lists, circuit boards and parts, playfield assemblies, some basic schematics, and wiring diagrams. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended [http://pinwiki.com/wiki/index.php?title=Pinball_Parts_Suppliers pinball parts suppliers]. Some Stern White Star Game manuals are available in PDF form on the Stern Pinball website. They are on the game specific pages of the Stern website. An index of games can be found in the right margin [https://sternpinball.com/support/game-manuals/ here]. 

As of April 2014, the Stern Pinball website no longer archives theory of operation and board schematics in PDF format. 

Be aware that although rare, some factory documentation contains errors in schematics, wiring, switch/lamp matrices, and solenoid assignments.

===Schematics===
Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids.

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===Service Bulletins===
Service bulletins detailed any problems or issues with games that were discovered after they were released.

Service bulletins detain all of games Stern are [https://sternpinball.com/support/service-bulletins/ here.]

As of 2014, service bulletins for Data East and Sega games are no longer directly available on the Stern Pinball website, but [https://web.archive.org/web/20130520091730/http://sternpinball.com/ServiceBulletins.shtml can be found on an older archived version of the website].

{| class="wikitable sortable"
|-
!Service Bulletin
!Date
!Game(s)
!Summary
!Notes

|-
|166
|2006, September 20
|Grand Prix & NASCAR
|Trough Up-Kicker Failure
|
|-
|162
|2006, July 11
|The Simpsons Kooky Carnival, MONOPOLY and TITANIC Redemption Games
|Electronic Coin Mech Coin Return Lever Sticks
|
|-
|161
|2005, March 21
|NASCAR / Grand Prix
|NASCAR / Grand Prix Enter/Exit Scoop Modification & 1-Way Gate Bracket Update Kit (502-5048-86); ONLY FOR NASCAR/GRAND PRIX GAMES with SERIAL NUMBERS LOWER THAN <195160 (NASCAR) and LOWER THAN < 19620 (GRAND PRIX) Production Prior December 2006
|
|-
|160
|2005, November 8
|NASCAR
|NASCAR SOFTWARE UPDATE (CPU/GAME ROM U210); ONLY FOR NASCAR GAMES with CPU Version 3.30 or LOWER
|
|-
|159
|2005, August 31
|NASCAR
|NASCAR T-Nut Cover & Target Foam Kit (SPI PN: 502-5042-00), EARLY PRODUCTION GAMES ONLY
|
|-
|158
|2005, August 26
|NASCAR
Early Production Games ONLY
|NASCAR 2-Pin OPTO Ground Connector in Backbox, EARLY PRODUCTION GAMES ONLY
|
|-
|157
|2005, June 20
|Terminator 3, The Lord of the Rings, Ripley's Believe It or Not!, ELVIS, Harley-Davidson 3rd Edition and The Sopranos
|New Version 8 of the Sound Operating System (O/S)* for the White Star CPU/Sound II Board bootFLASH file for EPROM; This new version O/S 8 is compatible with all previous versions of CPU/Snd II ROM’s.

|
|-
|156
|2005, May 5
|The Sopranos
|Cabinet Flipper Switches - Contact Pitting
|
|-
|155
|2005, April 15
|The Sopranos and future Pinball Games
|FYI: Lockdown Assembly & Front Molding Change during the production of The Sopranos Pinball and future Pinball Game Titles
|
|-
|154
|2005, February 20
|Lord of the Rings
|Lord of the Rings Post Upgrade Kit (502-5034-00) ONLY games prior to Feb. 2005 (production of LOTR games after Feb. 2005 have post in place).
|
|-
|Nr. 153
|2004, December 15
|Ripley's Believe It or Not!
|Ripley's Believe It or Not! Software Update
|
|-
|Nr. 152
|2004, August 27
|general
|FYI: STERN Pinball Flipper Evolution
|
|-
|Nr. 151
|2004, July 20
|Lord of the Rings
|Potential flipper & ring magnet fuse fatigue
|
|-
|Nr. 150
|2004, June 21
|general
|Back to Basics: Insertion/Replacement of EPROMS in SPI Games
|
|-
|Nr. 149
|2004, May 18
|Ripley's Believe It or Not!
|Potential Ball Trap by the Upper Left Pop Bumper (ask your Distributor for SPI Kit Nr. 502-5025-81)
|
|-
|Nr. 148
|2004, April 29
|The Lord of the Rings
|Balrog LED Module Installation, SPI Kit Nr.:502-5022-00
|
|-
|Nr. 147
|2004, January 19
|The Lord of the Rings
|Diverter Gate Adjustment Procedure
|
|-
|Nr. 146
|2003, December 18
|The Lord of the Rings
|FYI: The Lord of the Rings Tower Eject Learning Mode
|
|-
|Nr. 145
|2003, December 9
|Terminator 3 Rise of the Machines
|T3 Auto Launch Diode Harness Installation (SPI Part Number 502-5017-00)
|
|-
|Nr. 144
|2003, December 9
|The Lord of the Rings
|The Lord of the Rings Spanish Display & Speech Available
|
|-
|Nr. 143
|2003, October 22
|Terminator 3 Rise of the Machines
|T3 Software Update/Match Feature
|
|-
|Nr. 142
|2003, August 22
|Terminator 3 Rise of the Machines
|T3 Auto Launch Wire(s) or Coil Lug(s) Break Off
|
|-
|Nr. 141
|2003, August 13
|Terminator 3 Rise of the Machines
|Shooter Lane Switch Actuator Adjustment
|
|-
|Nr. 140
|2003, July 24
|Terminator 3 Rise of the Machines
|T3 Software Update v2.04 or Higher Eliminates POTENTIAL Reset Problem
|
|-
|Nr. 139
|2003, May 16
|Monopoly
|F21 (50vdc) Fuse Blows Intermittently, System Checks OK on
|
|-
|Nr. 138
|2003, March 21
|The Simpsons Pinball Party
|The display flashes a Tech-Alert upon Power-Up
|
|-
|Nr. 137
|2002, July 22
|Austin Powers
|CPU GAME ROM v3.01 Bug
|
|-
|Nr. 136a
|2002, June 21
|Playboy
|U7 Sound ROM Update DOES NOT RESOLVE the problem
|
|-
|Nr. 136
|2002, May 2
|Playboy
|U7 Sound ROM Change
|
|-
|Nr. 135
|2002, May 1
|Monopoly
|Optional Monopoly Butyrate Fix Kit (SPI: 502-5012-00)
|
|-
|Nr. 134
|2002, April 11
|general
|Difficulty in Playfield Glass Removal
|
|-
|Nr. 133
|2002, April 1
|Monopoly / Austin Powers
|CPU/Soundboard Modification Low Volume Setting Hum
|
|-
|Nr. 132
|2002, March 4
|Playboy
|Back To Basics: Using Your Adjustable Outlane Posts
|
|-
|Nr. 131
|2002, Jan. 23
|Monopoly
|Electric Company Sign / Backbox J2 Harness Re-dress
|
|-
|Nr. 130
|2001, Dec. 10
|Monopoly
|Tips & Tricks - The Water Works Rotating Flipper
|
|-
|Nr. 129
|2001, Oct. 22
|Monopoly
|Playfield Mylar, SPI Part Number: 820-5094-00
|
|-
|Nr. 128
|2001, Sep. 19
|Austin Powers
|Code Update v3.00 CPU/Display: Addition of Adj.60: Washington D.C. Enabled (Factory Defaults is "Off")
|
|-
|Nr. 127
|2001, Sep. 19
|Striker Xtreme / NFL
|Plastic Stadium Flashlamp Removal
|
|-
|Nr. 126
|2001, Sep. 19
|general
|The Bubble Level is Back!
|
|-
|Nr. 125
|2001, April 19
|general
|Quick Tip for Display Troubleshooting: U201 White Starboard System
|
|-
|Nr. 124
|2001, March 16
|Sharkey's Shootout/ High Roller Casino
|Software Update: Replay Bug Fix
|
|-
|Nr. 123
|2001, March 6
|High Roller Casino
|Ball Trap Fix @ Bottom Bumper
|
|-
|Nr. 122
|2001, Feb. 22
|High Roller Casino
|Roulette Wheel (Top and Bottom) Assembly
|
|-
|Nr. 121
|2001, Feb. 5
|Harley-Davidson
|Plastic (Butyrate) -15 Support Plate Kit(SPI Nr. 502-5003-67)
|
|-
|Nr. 120
|2000, Dec. 29
|Sharkey's Shootout
|Mystery Ball Magnet Fuse Fatique: CPU Software Code 2.04 Update
|
|-
|Nr. 119
|2000, Nov. 8
|general
|Pinball Preventative Maintenance Inspection
|
|-
|Nr. 118
|2000, August 21
|Striker Xtreme / Sharkey's Shootout
|Drop Target Replacement Procedure
|
|-
|Nr. 117
|2000, June 13
|general
|Please Join our Service Bulletin eMail Distribution
|
|-
|Nr. 116
|2000, June 12
|Titanic
|Titanic Redemption Game Potential Revenue Loss
|
|-
|Nr. 115
|2000, May 3
|Stiker Xtreme
|Stiker Xtreme Earnings
|
|-
|Nr. 114
|2000, Feb. 11
|Harley-Davidson
|Operator Alert #19 - Motor Relay
|
|-
|Nr. 113
|1999, Dec. 10
|Harley-Davidson
|HD Ball Guide... & Butyrate - 16... Kit
|
|-
|Nr. 112
|1999, June 7
|A13 >> Current
|CPU U218 & I/O U210 Pin-3 Removal
|
|-
|Nr. 111
|1999, Feb. 18
|South Park
|8MG E-PROM's for Expanded Speech & Sound Capabilities
|
|-
|Nr. 110
|1998, Nov. 24
|Space Jam >> Current
|Modular Stand-Up Targets: a new way to order
|
|-
|Nr. 109
|1998, Sep. 30
|Godzilla
|...Manual Addendum: Flipper Coils
|
|-
|Nr. 108
|1998, August 18
|Prior<<Batman Forever>> current
|"Sega"...& "Data East" ... Flipper Rebuild Kits
|
|-
|Nr. 107
|1998, August 13
|All Games (General)
|Fax Response Survey: How would you like your...
|
|-
|Nr. 106
|1998, June 2
|Multiple Games
|Large Dot Display Optional Enhancement Cable
|
|-
|Nr. 105
|1997, Nov. 21
|The X-Files
|...-Playfield Update Kit (500-6281-00)
|
|-
|Nr. 104
|1997, Sep. 25
|Multiple Games
|Future Parts & Service Pinball ...(Questionaire)
|
|-
|Nr. 103
|1997, July 14
|Playboy thru Rocky & Bullwinkle & Friends
|Solid State Flipper Bd. ( Non E.O.S.) conversion
|
|-
|Nr. 102
|1997, June 20
|The Starwars Trilogy-Special Edition
|FYI: What's New ("Y" Actuator Heavy Duty Sw.)
|
|-
|Nr. 101
|1997, June 10
|The Lost World: Jurassic Park
|Important Unpacking Information
|
|-
|Nr. 100
|1997, May 19
|The Starwars Trilogy-Special Edition
|Software CPU/Display Final Code Version
|
|-
|Nr. 99
|1997, May 13
|Multiple Games
|FYI: Correct P/F Glass Dimensions ...Wide Body
|
|-
|Nr. 98
|1997, April 8
|The Starwars Trilogy-Special Edition
|Addition of Reset Align. Bracket Kit
|
|-
|Nr. 97
|1997, April 8
|The Starwars Trilogy-Special Edition
|X-Wing Motor Bushing
|
|-
|Nr. 96A
|1997, May 12
|Space Jam >> Current
|Dot Matrix Display Bd. 4X Spacer/2X Bracket
|
|-
|Nr. 95A
|1997, April 11
|The Starwars Trilogy-Special Edition
|...Reed Sw. Replacement Kit...&Procedure
|
|-
|Nr. 94
|1997, March 3
|Lethal Weapon 3 >>Current
|Flipper Alignment Spots
|
|-
|Nr. 93
|1997, Jan. 27
|Space Jam
|FYI: ...problem in... I/O Power Driver Boards
|
|-
|Nr. 92
|1996, Dec. 5
|Apollo 13 >> Current
|FYI: MOSFETs in the White Star Bd. System
|
|-
|Nr. 91
|1996, Nov. 27
|Twister
|Magnet Processor Bd. & Disc Motor Updates
|
|-
|Nr. 90
|1996, Nov. 20
|Space Jam >> Current
|FYI: Sega Showcase Backbox
|
|-
|Nr. 89
|1996, Nov. 19
|Apollo 13 >> Current
|FYI: Switches
|
|-
|Nr. 88
|1996, Oct. 14
|All Games (General)
|Excerpt From Customer Fax
|
|-
|Nr. 86
|1996, Sep. 3
|Independence Day
|Potential Ball Trap in the Plastic Under-Trough
|
|-
|Nr. 85
|1996, May 15
|Twister >> Current
|New 2-Flipper Theory of Operation and Schematic
|
|-
|Nr. 84
|1996, March 5
|Golden Eye
|Fuse/Power Updates
|
|-
|Nr. 82
|1996, Jan. 23
|Apollo 13 >> Current
|The New "White P Star Board System"
|
|-
|Nr. 81
|1996, Jan. 9
|Apollo 13
|System Update
|
|-
|Nr. 80
|1995, Dec. 21
|Apollo 13
|Theory of Operation: P/F Mag. Intrface & 7-Seg.
|
|-
|Nr. 79
|1995, Dec. 18
|Apollo 13
|5 Amp to 3 Amp Slo-Blo Fuse Change
|
|-
|Nr. 77
|1995, August 24
|Current Games
|"What is this pinball machine trying to tell me?"
|
|-
|Nr. 75
|1995, August 22
|All Games
|CPU Board - Blanking Circuit Theory of Operation
|
|-
|Nr. 72
|1995, Feb. 17
|Mary Shelley's Frankenstein
|Creature: A Technical Overview
|
|-
|Nr. 70
|1995, Feb. 14
|Mary Shelley's Frankenstein
|Software Change Notice
|
|-
|Nr. 68
|1995, Jan. 27
|Frankenstein (+ games hereafter)
|New Service Feature: Bi-Directional Aud/Adj/Diag.

|}

==Technical Info==
===Schematics===
While these schematics were removed from Stern's web site quite some time ago, they can still be found using "the Wayback Machine". 

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===The White Star Board Set===
[[File:Stern WS Boardset.JPG|left|thumb|300px|Typical Early Stern White Star Boardset (Monopoly)]] 
The White Star System board set consists of three boards mounted to the the back box, but four boards total. The CPU / Sound board, I/O Power Driver board and the Display Power supply. Additionally, there is a dot matrix display controller mounted to the backside of the dot matrix display. On some games, the dot matrix display controller is mounted to the backbox instead. 

The first two White Star games, Apollo 13 and Goldeneye, both used an additional solid state flipper control board. Starting with Twister, the solid state flipper board was abandoned, and flipper control became an additional duty for the I/O power driver board. 

In addition to pinball machines, the White Star board set was used in several redemption games made by Sega and Stern. Some of the games are Wack-A-Doodle-Doo, Sega Sports, Titanic, and Monopoly redemption.
 
====CPU / Sound Board====
<center>
<gallery widths=500px heights=300px perrow=2 caption="Generations of the Sega/Stern White Star MPU">
File:A13MPU.jpg|<center>Sega White Star CPU/Sound Board 520-5136-00 Rev. D with 3 channel audio output (Apollo 13)</center>
File:Sega WS CPU Sound 520-5136-16 Rev. D.JPG|<center>Sega White Star CPU/Sound Board 520-5136-16 Rev. D (Wack-A-Doodle-Doo)</center>
File:Stern WS CPU sound.JPG|<center>Stern White Star CPU/Sound Board 520-5136-16 Rev. E (Monopoly)</center>
File:SternWhiteStarAtmelProcessor.jpg|<center>Stern White Star CPU/Sound Board II 520-5300-00 (LOTR and forward). U201, U213, and U413 are socketed on this board as a result of alkaline damage abatement.</center>
</gallery>
</center>
 

There are two versions of the White Star CPU/Sound board.

The board used in Sega machines starting with Apollo 13 (A13) and Stern machines up to Terminator 3 (T3) are the standard version as shown above with the BSMT2000. There were different revisions of this board, which included slight component changes and modifications. However, there were some distinct changes to the board from revision D to revision E. The Q9 transistor located just below U212 (RAM memory) was removed, and a two pin jumper (JP1) was added. Additional circuitry allowed for increased RAM memory from 8K to 32K. Jumper JP1 is used to select between use of a 6264 or a 62256 RAM. '''Note:''' While a 62256 RAM can be used in any game MPU, Sharkey's Shootout specifically requires a 62256 RAM. 

Stern machines starting from Lord of the Rings (LOTR) used a different version of the White Star CPU/Sound board called White Star CPU/Sound Board II or more commonly WhiteStar (modified), part #520-5300-00. Stern had this in-between version made because the BSMT2000 audio chip wasn't available anymore and having it reproduced was too expensive. The White Star II therefore uses an BSMT2000 emulation circuit consisting of an Atmel AT91R40008 microcontroller and an Atmel AT49BV1614-11TC 16Mbit flash memory. Later boards use a AT49BV162AT-70TI flash memory chip. Both flash chips are obsolete now. The boards are known for sudden sound failures sometimes because of a bad flash chip and it is advisable to buy a spare. If the amplifier section is good the most common cause for sound failures is the U414 Xilinx CPLD. This chip is a programmed by Stern via the JTAG connector. While some repairmen have the skill to replace the chip, only Stern can "flash" the code into the chip.

Note: Stern states that the Atmel version board is backwards compatible with the standard (BSMT2000) version, so it can be used in *some* White Star based games (in most cases, Stern branded White Star games only - including South Park and Harley Davidson) prior to LOTR as well. However, the only games which the board can be installed in must use 8mb EPROMs for the sound section versus the 4mb EPROMs more commonly found on Sega White Star based games. If the CPU/Sound board II is used in early games, Starship Troopers for instance, some sounds may not render correctly. 

Additionally...The original BMST2000 based board is not forward compatible with later games like LOTR, etc. 

The BSMT2000 based White Star sound system is nearly identical to the sound circuitry found on Data East/Sega soundboards 5020-5050-0x, 5020-5077-00 and 5020-5126-02.

The board uses TIBPAL16L8 PAL ICs. These are programmable logic chips Stern used to condense a great deal of TTL logic into a single chip. Each PAL is marked with a colored dot for identification and configuration management. U213 is one of these PALs that is within the battery corrosion area. It is readily available, already programmed under part number 965-6504-00 (blue dot), the only exceptions to the blue dot being Sharkey's Shootout which uses part number 965-5023-00 (gold dot) and Lord of the Rings LE with a shaker motor installed which uses a different part number (the standard LOTR without a shaker motor uses the standard 965-6504-00 but the software version supporting the shaker motor will only run on the alternative U213).

There are two more PAL chips on the board at U19 (yellow dot, 965-0136-00) and U20 (white dot, 965-0137-00). These aren't needed very often for repair of the sound section but they do fail now and then.
 
Sega first used standard TIBPAL chips and later switched to reprogrammable PALCE devices. The latest boards from Stern use GAL chips. In the old PAL chips, fuses are burned so they do not have a data retention period. For the programmable logic chips the data retention period is generally specified at 20 years or more at operating temperature. The first White Star boards are from 1995 Beginning in 2015, all with reprogrammable chips begin to exceed the data retention period and although big problems are not to be expected, it wouldn't be surprising if these parts begin to fail.

The programmable logic in the board design makes it harder to repair the boards because of the grey area it causes in the schematics as there aren't any logic diagrams of these available. In short; you don't know what they do so you don't know what the output should be.

'''"Blink Codes"''' do not exist for the 68B09E or the Atmel based MPU. With one exception (Atmel based board) anything blinking is a side-effect of improper board operation. The blinking may help you diagnose the actual board problem, but blinking LEDs are not driven with intent by the processors. i.e. There are no "Bally -17-like Blink Codes".

The single exception to this is LED1 on the Atmel based MPU. LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin # 157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another).

There are two [http://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] (Joint Test Action Group) connectors available on the Atmel based board. One connects to the Xilinx [http://en.wikipedia.org/wiki/Complex_programmable_logic_device CPLD] (Complex Programmable Logic Device). The other connects to the Atmel R40008 processor. The JTAG interfaces to this board and their use have not been documented publicly.

As of April 2014, schematics for the 520-5136-16 board are no longer available from Stern's website. 
As of April 2014, schematics for the 520-5300-00 board are no longer available from Stern's website. 

=====BSMT2000 DSP Info=====
[[File:BSMT2000.jpg||left||thumb||300px||BSMT2000 audio chip]] 
Like the earlier Data East boards, the first White Star generation uses a TI DSP for sound processing. The chip is just a relabeled mask programmed stock Texas Instruments TMS320C15NL-25 DSP. The 8K mask programmed ROM is custom programmed during manufacturing and can not be read out, reprogrammed, or altered in any way. Only the ones labeled BSMT2000 will work in a pinball. For prototyping, the TMS320P15NL-25 and TMS320E15NL-25 were available which included a more-or-less standard 27C64 EPROM. The pictures on the left shows a BSMT2000 and a TMS320P15NL-25 out of a Sega board. The hand labeled chips are rare but if you have one in your pin, you can read it out. The security fuse was not set on the device in the picture. If you build an adapter using a 27C64 and some logic which puts the DSP in microprocessor mode and does the address decoding it might even be possible to use the C10 and C15 devices because the internal ROM is not used in this mode.
 

=====WhiteStar Switch Circuitry=====
Both versions of rhe WhiteStar CPU/Sound board employ an 8 by 8 (8 switch columns, 8 switch rows) switch matrix. In addition to the typical switch matrix, an extra column of switches, which are dedicated to specific functions like coin door switches, appear on all WhiteStar games.

Flipper cabinet and end of stroke (EOS) switches are part of the dedicated switch set on games after Goldeneye.

A combination of microswitches, opto switches, leaf switches (on most drop target assemblies), and reed switches are used.
 

====Power Driver Board====
The Power Driver board supplies fused power, GI power and fusing, lamp matrix circuitry as well as coil and flash lamp drivers. A watchdog circuit also must communicate with the MPU periodically to allow the MPU to boot and operate properly. 

As of April 2014, schematics for the 520-5137-01 board are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-64 board (Sharkey's Shootout Tournament Edition only) are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-01 board (100 ohm resistors added on J2 aux. port lines) are no longer available from Stern's website. 

High current coils (50vdc) 1-8 (group 1) and 9-16 (group 2). Q15 and Q16 typically drive the left and right flippers respectively. 
Low current coils (20vdc) 17-24 (group 1) and 25-32 (group 2). 
 

Please be advised that four revisions of these board exist. The letter after the number indicates the revision. See below. All existing Stern schematics are wrong.

=====Revision D: First revision=====

=====Revision E: Second revision=====
[[File:Stern WS Driver.JPG|left|thumb|300px|Stern White Star I/O Power Driver Board Rev E]] 

*Not fully stuffed. Parts for flipper boards connector J4 and J5 are not stuffed.
 

=====Revision F: Third revision=====
[[File:IO driver rev F.jpg|left|thumb|300px|Rev F of the Sega/Stern IO Power Driver Board.]] 

*C25 changed from 470µF 100V to a 330µF 160V Snap-In capacitor
*U210 pin 3 is cut to allow for a 10% input voltage tolerance before resetting, aka "low line voltage". This was documented in Stern service bulletin #112 which can be found [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf here]. However, a better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 5% (to about 4.75VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

*J2 modified and 100 Ohm resistors R258 to R260, R273 -R277 added (see schematics)

 

=====Revision G: Fourth revision (not documented by Stern)=====
[[File:IO driver rev G.jpg|right|thumb|300px|Rev G of the Sega/Stern IO Power Driver Board.]] 
The most obvious change to the Rev G driver board is the addition of eight 100 ohm resistors under the J2 aux out connector (R258-260, R273-277). This board is backwards compatible with all machines that use the I/O Power Driver board. It is possible to add these resistors to the back of J2 for I/O board Rev F, jumping from the connector pins to the capacitors below the J2 connector to make the board compatible with those games that use the J2 connector.

This is the only version that will work with the TOPS system.

Parts deleted:

*Original R256, D228, R255 and C236 above U210 were removed

Modification 1:

J3 Pin 8 is no longer a key pin. The installed pin is connected to R255/R256 and to C236. The other side of these parts is connected to:

*R255 to D217 banded side like R245 to R251
*C236 to GND like C229 to C235
*R256 to U203 Pin 11 (LST lamp status)

The LST trace to D221 to D227 is missing. The diodes are still connected to the status output line of the VN02 solid state relays. It seems that this status is not queried by the game software or can just be ignored.

Modification 2:

*U210 Pin 3 is connected to R257.
*R257 is connected to GND but not stuffed!

Modification 2 is not necessary. A better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 10% (to about 4.50VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

New parts:
*R255 1K
*R256 39K
*R257 not stuffed
*C235 470pfd

===== Sharkey's Shootout Specific Driver Board =====
[[File:SharkeysShootoutWhiteStarMod.jpg|left|thumb|300px|Cuts and jumpers applied to the Sharkey's Shootout specific I/O Driver Board.]] 
The now defunct Stern web site containing schematics listed a few differences in the I/O Driver Board for Sharkey's Shootout. Those differences are identified in the image at left.

One other change to the board is shown on page 5 of the Sharkey's Shootout unique I/O Driver Board. Fuse F20 is changed from a 3ASB to a 4ASB.
 

===== RottenDog WhiteStar 5V Voltage Regulator =====
[[File:RottenDogWhiteStarVoltageRegulator.jpg|left|thumb|300px|RottenDog LM317 Replacement.]] 
The RottenDog aftermarket power/driver board uses the voltage regulator shown at left, primarily because the older LM317 voltage regulator has gone obsolete.
 

===== Lamp Matrix =====
The WhiteStar system is somewhat similar to previous lamp matrices designed by Data East, Sega and Williams. The main difference is instead of 8 lamp columns and 8 lamp rows (the typical 8 by 8 matrix), two additional lamp rows are used enlarging the matrix to 8 by 10.

===== TOPS Tournament System Driver Board Compatibility =====

Only the latest revision G is compatible with the Stern tournament system (TOPS). With earlier revisions while everything including the tournament sign seem to work ok a tournament can not be started. Pressing the tournament button will result in a 'Tournament Game Paused' message displayed on the DMD. The tournament button itself will also not light up during normal operation. The J3 Aux In connector has an additional pin instead of the key pin on these boards. Because of this the LST line to the lamp drivers goes nowhere on this revision.
 

====Display Controller Board====
[[File:Sega 520-5055-01 DMD Control Board.JPG|thumb|left|300px|Sega White Star Display Controller Board]]
[[File:AnnotatedDMDController.png|thumb|right|300px|Sega White Star Display Controller Board Layout with Ground Connections Shown]] 
The Schematics for this board can be found [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf here]. 

The display controller board doesn't contain circuitry to provide the on board 68B09E with a "reset" pulse. The reset signal is provided from the games MPU via a pin at the ribbon cable connection (J1 pin 20). The surface mount version of the board has provisions to provide a reset signal at U10, but the necessary components are not stuffed.
 

[[File:Stern WS DMD Controller.JPG|thumb|left|300px|Stern White Star Display Controller Board, surface mount version.]] 
As of April 2014, schematics for the 237-0255-00 DMD controller board (primarily surface mount components) are no longer available from Stern's website. 
 

[[File:SurfaceMountFailedSolderJoints.jpg|thumb|left|300px|A fractured solder joint (circled) on this board prevented the "power on" LED from ever lighting.]] 
The surface mount version of this board sometimes has dubious solder connections at some of the surface mount resistors and capacitors. The picture at left shows a fractured solder joint on the resistor in series with the "power on" LED. The LED would never light. Another fractured solder joint on the same board prevented the reset pulse from the MPU board from ever reaching the on board 68B09E.
 

====Display Power Supply====
[[File:Stern WS DMD PSU.JPG|left|thumb|300px|Stern 520-5138-00 Display Power Supply]] 

This WhiteStar game system high voltage power supply (for displays) is an evolution from the larger Data East power supply. The high voltage section of this board is nearly identical to the high voltage section of Data East power supplies 520-5047-01 and 520-5047-02. Of course, those earlier Data East power supply boards regulate and supply more than display high voltages (i.e. 5VDC). As such, the WhiteStar board could be made more compact while using almost identical parts.
 

====128 x 32 Dot Matrix Display====
All Sega and Stern White Star games make use of a 128 x 32 "standard" dot matrix display.
 

====White Star Manufacturing Quality====
[[File:WhiteStarFactoryUpdate.jpg|300px|left|thumb|Factory updates to the Sega/Stern White Star MPU.]]
[[File:WhiteStarMPUSolderSideFactoryMod.jpg|300px|right|thumb|Ceramic cap, 10 ohm 1/4 watt resistor, and a trace cut.]] 

Generally, White Star boards are manufactured quite well. The traces are very fine, making alkaline damage repair difficult. But, those batteries shouldn't be on the board, should they? The Atmel based MPU board uses a multi-layer PCB, which increases the need for clean component removal and replacement.

Pictured at left, are two factory updates to the original Sega/Stern White Star MPU (BMST2000 version). These are normal, and not "hacks".

As can be seen in the picture at right, a ceramic 100pF cap and a 10 ohm 1/4 watt resistor have been added and a trace has been severed. This modification results in the 10 ohm resistor and the cap being placed between BMST2000 "CLKOUT" signal at pin 6 and ground at pin 10.

An additional 100pF cap is placed between pin 5 "E" and 6 "!E" of U1.
 

[[File:WhiteStarU203CutAndDiode.jpg|300px|left|thumb|Another factory update to the Sega/Stern White Star MPU.]] 
Another factory update to the left of U206 involves two cuts, and the addition of a diode between D3 and R430. Again, this is not a "hack".
 

[[File:WhiteStarPCBSolderMask.jpg|300px|left|thumb|Small traces lead to some components on White Star boards, enabling better manufacturing quality.]] 
By the time White Star boards were being manufactured, improved methods of controlling solder temperature and junction temperature at the through-holes was much better understood. In the picture at left, the "spider" connections at some through-holes, allow less heat to be used to create quality solder joints.
 

===The Wire Coloring Code===
White Star games do not use color coding system. Instead, the wire color was marked accordingly in the associated documentation, (ie. a green wire with a brown trace is referred to as GRN-BRN, orange with violet is ORG-VIO, white is just WHT, etc.).
 

===Trough Opto Boards===
++++ Need pics of the single opto transmitter and receiver boards ++++++ 
[[File:Stern WS Trough Opto Transmitter.JPG|left|thumb|300px|Stern White Star Trough Opto Transmitter (Later Games)]]
[[File:Stern WS Trough Opto Receiver.JPG|left|thumb|300px|Stern White Star Trough Opto Receiver (Later Games)]] 
All White Star Games use trough opto boards at the location of the trough VUK which feeds the ball to the shooter lane. Earlier White Star games (Apollo 13 to Viper Night Drivin') use only a single opto above the VUK plunger. Later White Star games (Lost in Space to NASCAR / Grand Prix) use a two opto system. The lower opto serves a dual purpose. It is the opto just above the VUK plunger like earlier games, but is also designated as trough switch #4. The upper opto is designated as the "stacking opto". Its purpose is to identify when a ball inadvertently gets "stacked" above a ball located at the VUK plunger. 

To briefly summarize the operation of White Star VUK opto boards, if an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch. The components used on the opto receiver board are designed to do as such. 

The transmitter side is simply an ultra-red LED with a current limiting resistor. The receiving opto is the same style ultra-red LED, and is able to detect the light wavelength emitted from the transmitting LED. By using discrete components on the receiving side, the appropriate signal is sent to the CPU via the switch matrix return (row). When LEDs are paired together in this type of fashion, the receiving LED emits a very small amount of voltage, when the proper light wavelength is present. By employing such a design, failure on the receiver opto side is more common. 

This particular system is contrary to how Bally / Williams WPC CPUs handle opto pairs. Equally, WPC games employ infrared (IR) opto switch pairs. If interested in learning the theory of operations for the White Star opto trough upkicker boards, please consult the manual. Sega / Stern have included some excellent, detailed, technical documentation within their manuals. 

As of April 2014, schematics and troubleshooting info for the trough upkicker dual opto boards are no longer available from Stern's website.

Once significant source of trouble with these trough boards is fractured header solder joints. 

===Magnet Processor Board===
[[File:Sega mag driver board.jpg|300px|thumb|left|Sega 520-5143-00 Magnet Processor Board]] 
Only two Sega games used this style of magnet processor board - Twister and Goldeneye. When U1 for Twister is installed in the board, the board's part number is 520-5143-01. The part number for the board when U1 is written for Goldeneye is 520-5143-02. Difference between the board used on each game is the different custom PIC / GAL chip used at position U1 and the Goldeneye board has R10, R11, R12, R13, D11 and D12 stuffed. This is not always the case with boards for Twister.
 

===Flippers===
[[File:Stern Flipper Assy.JPG|left|thumb|300px|Typical White Star Left Flipper Assembly (Monopoly)]] 
All Sega / Stern White Star flipper assemblies are solid state controlled. Apollo 13 and Goldeneye are the only two White Star games which use a separate solid state flipper control board located in the game's lower cabinet. Starting with Twister, the flipper board was abandoned, and circuitry for the flippers was solely controlled by the FETs on the power driver board. 

Please note that the adjacent pic of the White Star flipper assembly has a Williams flipper link / plunger installed.

The drive circuit for White Star games is different than traditional flippers. The flipper coil is single-wound. There is no "hold" winding, just a single "kick" winding. Because the flipper will get hot if the kick winding runs continuously, after the initial upstroke, the computer continuously cycles the coil on so that it stays up. According to the manual, the flipper is pulsed about 1/12 of the time.

The flipper coil must have a snubbing diode.

A normally closed EOS switch is present. The purpose of the EOS switch is to detect when a fast-moving ball has forced the flipper down ("foldback"). Unlike a traditional or Fliptronic mechanism, the EOS switch is not used to detect end of stroke. That is, the EOS switch closing does not cause a switch from "kick" to "hold". If the flipper is supposed to be up, and the EOS switch opens, the game will re-energize the flipper coil. This helps with some features, particularly "laser" kickers that fire the ball into the flippers. The EOS switch should be present for improved play, but if it's broken, the flipper will work for the most part. However, in some instances, a flipper with a broken or missing EOS switch may be noticeably weaker. If a flipper seems weak or lethargic, the flipper mechanisms have been rebuilt, and the EOS switch is broken, try replacement of the EOS switch first before considering other options.
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
Solid state pinball machines typically have a built in system for audits and adjustments. All White Star based machines use a system called "Portals". The Portals interface is a carry over from the last two Sega games (Baywatch and Batman Forever) which used the original Data East board set.

====Portals (Coin Door Test Buttons)====
[[File:Stern white star coin door inside.JPG|300px|thumb|left|The Portals control panel used on most White Star games (Monopoly)]] 
The Portals system has a very user friendly, simple navigation system. Unlike previous Data East / Sega games, having to scroll through all of the audits and adjustments is a thing of the past. Diagnostic testing (including game specific assembly tests), audits, and adjustments can all be quickly accessed via the initial display menu graphical interface. The 3-button control panel (in most cases, except some earlier White Star games) used to access Portals is located on the coin door.
 

<center>

<gallery widths=300px heights=120px perrow=3 caption="DMD Screens during Various Tests in Portals ">
File:Stern WS test switch.JPG|<center>Switch test (similar to switch edge test in Williams speak)</center>
File:Stern WS test active switch.JPG|<center>Active switch test (similar to switch level test in Williams speak)</center>
File:Stern WS test ded switch.JPG|<center>Dedicated switch test</center>
File:Stern WS test lamp options.JPG|<center>Very flexible lamp test options</center>
File:Stern WS test single coil.JPG|<center>Coil test</center>
File:Stern WS test trough full.JPG|<center>Trough clear, but equally a good test for the trough and shooter lane switches</center>
File:Stern WS test trough 3 in trough 1 shooter.JPG|<center>Advancing through trough clear</center>
</gallery>
</center>

=====Setting Free Play=====
 

===Coin Door Switches===
[[File:Stern coin door buttons.JPG|300px|left|thumb|Coin door Switches Located Inside a White Star Game (Monopoly)]] 
Most White Star games have two switches located on a bracket inside the coin door (hinge side). The upper switch is the memory protect switch. This switch is used so that nothing can be written to the memory, unless the coin door is open. The memory protect switch is not part of the switch matrix, nor is it one of the dedicated switches. Although it does connect to the CPU / Sound board via the same connector as the dedicated switches, its state is processed by a different chip (U213) versus the dedicated switches (U206). 

The lower switch is an interlock style "kill" switch. This kill switch is used to kill all power to the solenoids, when the coin door is opened. Since it is an interlock style switch, it can either be depressed (when the coin door is closed), or it can be extended outward to turn the switch on. To extend the switch to the on position when the coin door is open, grasp the switch, and gently pull it out to the lock position. 

The kill switch is a double pole switch. Wiring to one pole of the kill switch is BLK-YEL and BLK-YEL, while the other is RED-WHT to WHT-RED (yes, the colors do not match!)
 

== Problems and Solutions ==

=== Power Problems ===
===Fuse Table===
[[File:WhiteStarFuseTable.jpg|400px|left|thumb|The typical fuse table. This table appeared in the Stern Sopranos manual.]] 

=== MPU boot issues ===

Damage resulting from alkaline corrosion is the most prominent reason for the MPU to fail to boot.

If the GI lamps are blinking at about a 1Hz rate, this means that the MPU is not booting and that the I/O Driver board is sending a reset pulse to the 68B09E on the CPU/Sound board.

The following can be examined:

*Alkaline corrosion
*Inter-board ribbon cable fault inhibiting the reset of the CPU/Sound board watchdog timer DS1232. The timer is reset via signal DRV0, a lamp matrix signal.
*Failed ROM. Note that the ICs on WhiteStar CPU/Sound boards are ALL installed notch down. Installing a ROM upsidedown and powering on immediately destroys the ROM.

==== Relocating the Battery from the MPU board ====
[[File:WhiteStarAlkalineDamage.jpg|300px|thumb|left|The aftermath of batteries which leaked. This board is beyond repair, and good only for salvage parts.]]
Relocating the 3xAA batteries off the MPU board or installing other alternatives for memory retention is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. 

One option is to install a remote battery holder, and place the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) components of the MPU board. Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually. 

Another option is to install a memory capacitor. This method is considered to be better than a remote battery holder, because memory capacitors are not prone to leakage like alkaline batteries. The only drawback is that the memory capacitor has to be properly recharged to be effective. If a game has the potential of sitting dormate without being turned on for extended periods (typically months), the memory capacitor may not hold the memory. 

A third option is to install a lithium battery with a battery holder. Lithium batteries are much less likely to leak than alkaline batteries, and they do not need to be recharged.

Whatever you do, GET THE BATTERIES OFF THE BOARD! It's not a matter of if they will leak, it's a matter of when. WhiteStar boards are pricey to replace, and repair is difficult/expensive/even impossible due to the very fine traces used on the board. 

[[File:WhiteStarRemoteBatteryHolderAnnotated.jpg|300px|thumb|left|A White Star MPU Board with Remote Battery Pack Connected. The Positive (+) terminal is circled. D200 and D201 are highlighted inside the rectangle. Note that the battery installation date is recorded with a Sharpie. Also note the long wires, allowing the holder to hang well below the backbox boards, another precaution for leaky batteries.]] 
Adding a connector between the battery pack and the MPU board is a good idea. In doing this, the battery pack can easily be removed from the MPU board. Plus, if the batteries are forgotten, and do leak, the MPU board may not have to be removed to add another battery pack. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is available, a jumper can be soldered in the first battery position. Likewise, a diode can be placed in this position instead. Using a diode instead of a jumper will prevent the batteries from being charged and 'cooked' by the game if blocking diode D201 on the MPU board fails. Keep in mind that a second (redundant) diode added to the circuit will reduce the backup voltage to the RAM memory by .5 to .7 volts. Install a 1n4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the (+) terminal marking on the MPU board, and away from the battery pack. 

On the MPU, solder the battery cables: positive (red wire) to the "+" pad and ground (black wire) to the "-" pad.

Since the MPU board is already out, another good practice is to check the D201 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. Alkaline batteries do not like being charged. They will heat up, and fail rather quickly. In worse cases, the new batteries can even leak or explode if charged. Testing the D201 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D201 diode with a 1N5817 (a 1N4004 will work in a pinch), or add a redundant 1N4004 to the battery pack. Once again, if a second (redundant) diode is added to the circuit, it will reduce the backup voltage to the RAM memory by .5 to .7 volts 

Testing the D200 diode is a good idea too. The D200 (1N5817) diode is used to keep the backup batteries from powering the complete MPU board when the power is off. A symptom of a failed D200 diode are batteries which deplete rapidly.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the '''VBATT''' test point on MPU board. All battery packs are pretty cheaply made, and failures "out of the box" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:White Star Mem Cap.JPG|300px|thumb|left|Installation of a Memory Capacitor]]
A memory capacitor is a great choice for memory retention, provided that the game will be turned on more frequently than not. If the game will not be turned on for several months, the memory cap may not stay charged. In turn, the memory may not be retained. 

It is recommended to use a 1F (Farad) 5.5v memory capacitor. The lead centers on a common, button memory cap are shorter than the "+" and "-" through holes where the factory battery holder was installed. To overcome this, solder a short wire onto the negative lead of the cap. Then, bend the lead at a 90 degree angle, so it is now parallel to the bottom of the memory cap. Place the positive lead of the memory cap into the "+" of the board, and then place the wire from the negative lead into the "-" of the board. Solder both leads in place. 

Please note that when using a memory cap, the D201 diode must be removed (or jumped), and a 0 ohm jumper or a 100 ohm resistor (or similar value) should be installed. This purpose of removing the D201 diode is so the memory cap can be properly charged when the game is on.
 

==== Repairing Alkaline Corrosion ====
[[File:WhiteStarInsidiuosCorrosion.jpg|300px|right|thumb|Corrosion can hide in many hard to find places.]]
Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the batteries are mounted on the top of the board with plenty of board beneath it for the corrosion to leach onto. Components well below the battery holder are often damaged.

Remember, battery corrosion is alkaline. Harkening back to the dim and distant past, remember your Chemistry 101. Alkaline is neutralized with acid. Most commonly used is vinegar, since it is an acid. Diluting the vinegar to half strength by adding an equal amount of water (50/50) is a good idea to prevent adverse impact to adjacent areas of the board.

[[File:WhitStarAlkalineCorrosion-1.jpg|300px|left|thumb|This MPU sustained alkaline damage. Sockets for the 68B09E processor and the 6264 RAM have been removed.]]
[[File:WhitStarAlkalineCorrosion-2.jpg|300px|right|thumb|More components removed, the alkaline damaged traces sanded, and the damaged area treated with 50/50 vinegar and water.]] 
Argh! The MPU pictured at left has sustained alkaline damage. In this case, the damage was repairable. Most of the time, alkaline damage to White Star MPUs is more substantial and beyond economical repair.
 

[[File:WhitStarAlkalineCorrosion-3.jpg|300px|left|thumb|Bare copper traces tinned.]]
[[File:WhitStarAlkalineCorrosion-4.jpg|300px|right|thumb|All components (or sockets) reinstalled, and nearly ready for test.]] 
The completed board shown on the right took a few hours to cleanup, repair, verify, and game test.
 

[[File:StarShipTroopersMPU.jpg ‎|1100px|center|thumb|A StarShip Troopers MPU, with widespread alkaline corrosion abated professionally.]]
[[File:WhiteStarComponentLayout.jpg|1100px|center|thumb|Components in WhiteStar Corrosion Area. Click to enlarge. Note: "104" refers to .1uf ceramic cap, 470 refers to 470pf cap.]]

===== Continuity Chart of Pin Outs in Battery Damaged Area =====
Just below the battery holder, the CPU EPROM and RAM both reside. Both of these chips and their sockets are susceptible to battery damage. Provided that the alkali damage breached the chip sockets, it is always best to check continuity on the new work performed. Below is a chart of the pin outs between the RAM (U212), EPROM (U210), and CPU (U209) chip. This chart will hopefully come in handy should repair of this area is necessary.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Signal
!68B09E Pin (U209)
!ROM Pin (U210)
!RAM Pin (U212)
!PAL Pin (U213)
!Other
|-
| Vcc ||7||32||28||20||
|-
| GND ||1 & 39||16||14||10||
|-
| A0 ||8||12||10||||
|-
| A1 ||9||11||9||||
|-
| A2 ||10||10||8||||
|-
| A3 ||11||9||7||||
|-
| A4 ||12||8||6||||
|-
| A5 ||13||7||5||||
|-
| A6 ||14||6||4||||
|-
| A7 ||15||5||3||||
|-
| A8 ||16||27||25||||
|-
| A9 ||17||26||24||16||
|-
| A10 ||18||23||21||15||
|-
| A11 ||19||25||23||8||
|-
| A12 ||20||4||2||9||
|-
| A13 ||21||28||26||3||
|-
| A14 ||22||29||---||2||U211-2 (XA0)
|-
| A15 ||23||3||---||1||U211-5 (XA1)
|-
| A16 ||31||13||11||||U211-6(XA2)
|-
| A17 ||31||13||11||||U211-9 (XA3)
|-
| A18 ||31||13||11||||U211-12 (XA4) - Prior to rev. E boards
|-
| D0 ||31||13||11||||
|-
| D1 ||30||14||12||||
|-
| D2 ||29||15||13||||
|-
| D3 ||28||17||15||||
|-
| D4 ||27||18||16||||
|-
| D5 ||26||19||17||||
|-
| D6 ||25||20||18||||
|-
| D7 ||24||21||19||||
|-
| /ROMCS ||---||22 (BSMT2000) 24 (Atmel)||---||19||
|-
| /RAMCS ||---||---||20||18||
|-
| /E ||---||24 (BSMT2000) 22 (Atmel)||22||4||U1-6
|-
| /CS ||---||---||26||||Q9-1 - rev. D or JP1 (8K) - rev. E
|-
| R/W ||32||---||27||7||
|}

 

==== Connecting a logic probe to the MPU ====
[[File:WhiteStarConnectingALogicProbe.jpg‎|300px|thumb|left|Connecting a logic probe to a Sega/Stern White Star MPU]]
[[File:WhiteStarModifiedConnectingALogicProbe.jpg‎|300px|thumb|right|Connecting a logic probe to a Stern White Star (Modified) MPU]] 
Connecting a logic probe to a Sega/Stern White Star board set (left) is simple. 
Both 5V and Ground test points are made available on the MPU board.

Connecting a logic probe to a Stern White Star (modified) board set (right) is simple too, but a 5V connection point isn't provided. 
Connect the positive lead of your logic probe to either side of the inductor labeled FB1.
 

==== Using a PC Power Supply For Bench Testing ====

===Low 5VDC and Game Resets===
Some symptoms of a game which repeatedly resets upon boot up are:

#General illumination lamps will repeatedly flash on and off (the GI relay can be heard clicking on / off).
#The DMD will display the initial boot screen, show the display ROM revision number, go blank, and then repeat this process.
#The sound board (depending on the age of the game) may only emit a "blip" sound or a shorter than usual initial sound clip.

In some of the above instances, the DMD display may or may not light up at all. 

The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer. 

U413, which is located on the CPU / sound board next to the reset button, is a [https://datasheets.maximintegrated.com/en/ds/DS1232.pdf Dallas Maxim DS1232] monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC. 

If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. Another location to measure the +5VDC is right on the metal casing of the LM338K regulator (U19), If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338K regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto transmitter board may be at fault. 

Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. The +5V test point on the CPU / sound board is located just to the left of the 6809EP CPU chip (U209) on the board. If the voltage drastically differs between the measurement of the I/O Power Driver Board and the CPU / sound board, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board. 

==== DS1232 Voltage Watchdog ====
[[File:WhitestarDS1232Pin3Clipped.jpg|left|thumb|300px|While this looks to be an error, it's actually a factory modification to the DS1232 reset generator. While this part is on the CPU/Sound board, there is an identical part on the driver board, which will have pin 3 clipped also. On the CPU pin 2 (Time Delay Set) might also be clipped. Pin 2 and 3 are left unconnected from the factory on the WhiteStar (modified) CPU/Sound board.]]
Both the WhiteStar MPU and Driver boards employ a DS1232 voltage watchdog. From the Sega and Stern factory, pin 3 is almost always clipped. Pin 3 is used to select the voltage tolerance the chip is to enforce.

A discussion regarding the proper connection of pin 3 was offered by John Robertson on rec.games.pinball, and is copied below.

Begin discussion...

You read it here (rec.games.pinball) first!

Looking into a problem with our Roller Coaster Tycoon where the game
would cut out the lights and coils for up to a second at random
intervals. This would happen perhaps once or twice every day or two.

Digging into the game I noticed that the Dallas supervisor chip used in
both the original Stern and the Rottendog replacement Driver Board both
left pin 3 (LOP) floating. Now this pin is there to select the Vcc
tolerance - if grounded it is 5% and if tied to Vcc it is 10%. However
the schematics now show pin 3 as floating.

Sega Service Bulletin SB112 (June 7, 1999) had recommended cutting pin 3
(to floating) on both Dallas DS1232s (MPU & Driver PCBs) where the
factory (at that time) had connected pin 3 to Gnd (5%). Sega, then Stern
continued this practice of either cutting or leaving pin 3 floating.
Rottendog also did this on their replacement board.

http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf

I was curious what would happen and if this idea of cutting the leg or
leaving it floating was recommended by Dallas. So I pulled up both the
original Dallas documents and the Maxim Application Note and in neither
case did they suggest that pin 3 should be floating - no connection.They
said it was to be connected to either Gnd or Vcc.

https://datasheets.maximintegrated.com/en/ds/MAX1232.pdf

https://pdfserv.maximintegrated.com/en/an/AN581.pdf

I then asked Maxim (who now make Dallas Semi chips) to comment on what
happens when pin 3 is floating - they replied today (Nov 25, 2019):

Thank you for contacting us.

It is not recommended to leave the TOL pin open since it is a digital
input and noise can make it oscillate, there is no internal pulling
resistor, so please do indeed connect it to GND or Vcc.

Regards,
Javier Monsalve
Maxim Applications

We had already tied pin 3 to Vcc (+5) as of Nov 23, 2019 to check my
assumption that floating was wrong, and the intermittent cutting out
problems had indeed disappeared!

The game has been running for days now with no hiccups and we shall be
leaving it running at least one more day before sending it to its new
home. We are monitoring the Vcc with a Mooshimeter logging 5V, to see if
Vcc drops below any reasonable threshold and a Heathkit logic probe
monitoring the R (pin 5) of the DS1232 as the Heathkit logic probe
stores momentary state changes (turns on a 'memory' LED).

Therefore, based on our tests, and the advice from Maxim, the
manufacturer of the DS1232 IC Supervisor chip, we can now say that you
need to tie pin 3 of the DS1232 to Vcc! Do NOT leave it floating as per
Sega Service Bulletin SB112!

Hope this helps!

John :-#)#
 

[[File:RottenDogDS1232SolderBridge.jpg|left|thumb|300px|An (probably) intentionally created solder bridge on a RottenDog power/driver board, bridging pins 3 and 4 on the DS1232 voltage watchdog, selecting 5% (4.75VDC) tolerance.]] 
RottenDog WhiteStar power/driver boards may have a solder bridge across pins 3 and 4 of the DS1232 voltage watchdog. This is done to prevent pin 3 from "floating" and instead actively select the watchdog voltage.

Quoting Ed from Great Plains Electronics on PinSide...

It appears pin 3 (voltage tolerance pin) was left floating on their (RottenDog) design. That input is supposed to be tied high (reset at 4.5V or 10% VCC tolerance) or tied low (reset at 4.75V or 5% VCC tolerance) and should never be left floating. Adding the jumper from pins 3 to 4 selects the 5% tolerance. If the 5V line dips below 4.75V then your board will reset (which is what it is supposed to do with that setting).

Jumpering pin 3 to pin 8 (5VDC) selects the 10% tolerance.
 

[[File:DS1232MPU.jpg ‎|left|thumb|300px|The MPU DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
[[File:DS1232Driver.jpg ‎|right|thumb|300px|The Driver board DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
In these two images, the DS1232 voltage watchdog, pin 3, has been tied to a convenient source of 5VDC, selecting 10% (4.50VDC) tolerance.
 

[[File:WhiteStarModifiedDS1232.jpg ‎‎|left|thumb|300px|The DS1232 on a WhiteStar (modified) MPU, and connection that can be made.]] 
Some (if not all) WhiteStar (modified) MPUs leave pin 3 of the DS1232 floating. A trace from pin 3 leads to a through-hole for an unstuffed part. This through-hole can be exploited by adding a jumper as indicated in the picture at left. Installing this jumper configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance.
 

[[File:WhiteStarDriverRevGDS1232Connection.jpg ‎ ‎‎|left|thumb|300px|The DS1232 on a WhiteStar Revision G Driver Board, and connection that can be made to 5VDC, selectiong 10% tolerance or 4.5VDC.]] 
Revision G of the WhiteStar Power/Driver board leaves pin 3 floating even though R257 is provided to jumper the pin to ground. A better option is to jumper pin 3 to 5VDC which configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance. An easy method to achieve this is shown at left. This method uses the available through hole at R257.
 

==== Poor or Damaged Sockets Cause Reset ====
[[File:WhiteStarCrappySocketAnnotated.jpg‎|300px|thumb|left|A damaged EPROM socket from a Sega/Stern White Star MPU]] 
A damaged socket for either the game ROM or the 6264 RAM can cause a game to continually reset. This happens because the CPU can not fetch and execute instructions from the game ROM, or it is unable to read/write data to/from the RAM correctly. A simple replacement of damaged OEM sockets sometimes corrects a reset issue.
 

====Game Resets with DMD Controller Board Connected====
This may be a bit of an anomaly, but it is worth mentioning. If when the DMD controller board is connected without the data line ribbon cables, and the game continues to reset, replacement of BRDG21 may be required. 

In one particular instance, a game was resetting continually with only the +5v / ground connection connected to the DMD controller board. If the board was not connected, the driver board would output ~+5VDC. If the DMD controller board was connected, the driver board's logic line would dip down to around +4.85VDC. Logically speaking, this type of symptom somewhat points to the DMD controller board having issue. However, the end result was replacement of BRDG21 per Stern tech support. 

It is worth mentioning that the bridge rectifier did test correctly (using a DMM in diode test) both in circuit and out of circuit, but these tests were conducted while the bridge was not under load. 

===Solenoid/Flasher, and Controlled Lamp problems all at the same time===
[[File:CorrodedWhiteStarHeaderPinsCropped.jpg|300px|thumb|right|Corrosion on driver board header J1, prevented data bus signals from reaching the drive buffer chips. Image courtesy of PinSider JamesH007]] 
If the game is experiencing issues with multiple devices (coils, flashers, controlled lamps) that are controlled by the driver board, and those devices are "separated by 8 bits", there is a good chance that the data bus that connects to each of the 74HCT273s driver chips on the driver board has lost continuity somewhere between the associated MPU board dual row connector and the driver chips.

This can include:
*the dual row header on the MPU board
*the ribbon that connects the MPU and driver board
*the dual row header on the driver board
*the traces leading from the dual row header on the driver board to the 74HCT273s

The image at right shows a corroded connector which led to inoperative coils driven by Q3, Q11, Q19 and Q27 (note the gap between these parts is 8 transistors, the width of the data bus).
 

===Solenoid problems===

====Game Notes====
*NASCAR solenoid test swaps the order of output for coils 25 and 26. While the display calls out coils 25 and 26 correctly, in fact coils 26 and then 25 fire.

[[File:NASCAR-1.jpg‎|300px|thumb|left|NASCAR shooter lane switch with wireform correctly in place.]]
[[File:NASCAR-2.jpg‎|300px|thumb|right|NASCAR shooter lane switch with wireform bent/stuck and switch closed.]] 
Stern NASCAR, and possibly other games, use a switch in the shooter lane to detect the presence of a ball. If the switch is closed, and the auto-launcher coil fires to launch the ball, and the game doesn't detect that the switch has opened after firing the shooter lane auto-launcher, then the game assumes that the auto-launcher has malfunctioned in some way, and reports an error on the DMD.
 

====Testing MOSFETs and TIPs====
[[File:IO_test_points.jpg‎|300px|thumb|left|Driver Test Points TPL1 above Q16 (left) and TPL3 above R302 (right) are used to fire the transistors on the driver board.]] 

The Sega/Stern I/O Power Driver Board contains 32 driver transistors on the bottom right of the board. Transistors Q1-Q16 are MOSFETs – either 20N10Ls or P22NEs. These are used to drive high current coils like the flippers and other heavy loads. These are connected to devices through J8 and J9. Transistors Q17-Q32 are TIP 122s and are used for driving low power solenoids such as flash lamps. These are connected to devices through J6 and J7. 

All of these drivers are computer controlled directly from the CPU board through a flip-flop on the driver board. Q1-Q8 are controlled through U1 on the driver board, Q9-Q16 are controlled through U2, Q17-Q24 are controlled through U3 and Q25-Q32 are controlled through U4. Each one of these chips is selected by the address decoder at U204. There is another address decoder at U205 and both of these decoders must be working properly for the I/O board to function. 

It is possible to test the driver transistor and the solenoid in the circuit from the driver board. Above Q16 on the driver board is a test point marked “TPL1 FET”. Not a lot of people know what this is for. Per the manual: “This will apply 3.4v to the gate of the MOSFET transistor thus switching it on.” You’ll notice that the bank of resistors from R1 to R16 have a white stripe on one side closest to the MOSFETs. By using a jumper wire from TPL1 to the lug of each resistor in the white band, you can fire the coil associated with that resistor/MOSFET. Each resistor number corresponds with the same MOSFET number. So R1 fires Q1, R2 fires Q2, etc, etc. TPL1 is for testing all the FETs from Q1 to Q16. 

If you look in that same photo above R302, you will notice “TIP TPL3”. This serves the same purpose as TPL1 except for the TIP transistors on the driver board Q17-Q32. By jumping from TPL3 to the leg of the resistor in the white band, you can test each of the TIP122s and their associated circuitry. This is a useful diagnostic step if the machine will not fire a coil in self-test or during a game. If you can fire the transistor with this test, you know the problem is with the computer control circuitry for the solenoids. However, if it doesn’t fire, it could be a problem with the transistor or the associated components in that solenoid circuit. 

If one of Q1-Q16 is bad, it is best to replace it with an IRL540N (see below). If one of Q17-Q32 is bad, it is best to replace it with a TIP102. 
=====Screening Error On the Board=====
You might notice in the photo (prior section) that the white stripe is on the lower leg closest to the transistors of R1-16 and R25-32, but there is no white stripe on R17-24. Instead the stripe is on the lower leg of the resistors R200-R207. This is a screening error on the board but electrically match to the correct legs of resistors R17-24. As an example, if you want to test Q17, touch the leg of resistor R200 that’s in the white strip and Q17 should fire. The same holds true for R201/Q18, R202/Q19, etc etc. 

====Can an IRF540 replace a P20N10L, P22NE10L or an IRL540?====
[[File:IRL540vsIRF540.jpg‎|300px|thumb|left|Danger Will Robinson...the IRF540 installed at Q6 shown above, is the wrong part. The original 22NE10L should be replaced with an IRL540, like the one to it's immediate right.]] 
No.

The White Star driver board first used STP20N10L FETs to drive high current circuits, like solenoids. When they were discontinued later boards used the STP22NE10L. Since the 22NE10L is obsolete and even the current replacement, the
STP40NF10L is hard to find, the IRL540 or IRL540N are the recommended replacements. If available get the IRL540N because it has a higher drain current rating of 36A.
 While the drive specs of the IRF540 seem comparable, they are not. Using an IRF540 as a substitute can cause the associated coil to lock on, toast the coil, then blow the FET. The L in all of the original parts indicate that it is a logic level FET.

Per a good friend of Pinball, Ed Krzycki, via [http://groups.google.com/group/rec.games.pinball/browse_frm/thread/de777f6eec98a687/330e0d47fde12c6f?hl=en&lnk=gst&q=irf540# RGP post]...

''Nope -- an IRF540 is not a good sub for the IRL540 or 22NE10L.''

''The "L" parts have TTL compatible gate voltages. A TTL gate has a minimum high level output voltage of about 2.4 volts. To turn on any N-channel MOSFET transistor - the Gate voltage must be sufficiently high enough as listed by the spec sheets VGS(th) voltage.''

''The IRL540 requires a Gate threshold voltage of 1 to 2 volts. A TTL part exceeds this voltage so a TTL gate's high level output would guarantee the gate would turn completely on. The IRL540 is guaranteed to have "turn on" and "turn off" voltages that are compatible with a standard TTL device.''

''The IRF540 requires a Gate threshold voltage of 2 to 4 volts. A TTL gate *might* turn this part on if the specific part being used has a threshold in the 2 to 2.4 range. If the specific part being used has a threshold closer to the 4 volt range then the MOSFET probably won't turn on properly or fully. The IRF540 *might* work or it might not work. And no guarantees that a working part would remain working if ambient temperature changes.''

''Another aspect to an IRF540: An IRL540 operates more as an on-off switch but an IRF540 does not. Depending on voltages, an IRF540 can operate as an on-off switch and can also operate anywhere in between on and off (half on) depending on input voltage. If the TTL device cannot quite drive the gate voltage high enough then the MOSFET may end up partially conducting. This can have different results depending on how much it is turned on.''

''The 22NE10L has similar characteristics to that of the IRL540 as far as gate threshold voltages.''
 

====Adding a Real Knocker to White Star Games====

Some White Star games (like Starship Troopers) are not equipped with a real, old fashioned, knocker. We all love knockers, don't we?

To add a real knocker to your White Star game, follow this procedure.
Note: in this procedure, we locate the knocker in the head, attempting to increase the knocker's impact. For cabinet installation, take advantage of the wiring already provided for the European Token Dispenser.

[[File:AddingAKnockerBigPicture.jpg|left|300px|The objective...]] 
In the picture at left, we show all the components necessary to add a knocker. The new knocker is circled, top left. We've used an in-line connector along the wiring, also circled, lower left. The power and ground connections are noted by the rectangles.
 

[[File:SSTManual.jpg|thumb|left|300px|A snippet from the Sega Starship Troopers manual showing coils, and in particular, coil 8, the European Token Dispenser.]] 
First we need note that the European Token Dispenser solenoid drive is unused in domestic (USA) games. Coil power and drive connections are wired into the game. They can be found in the cabinet bottom. We could simply connect the knocker to that connection, but in this example, we mount the knocker in the game head.
 

[[File:SolenoidPowerConnection.jpg|thumb|left|300px|Adding a wire to provide the knocker with 50V power.]] 
Here I've stuffed another wire (yellow with purple tracer) on top of the solenoid power supply at J10, pin 5. This wire will eventually be connected to the banded side of the knocker coil.
 

[[File:SolenoidGroundConnection.jpg|thumb|left|300px|Adding a wire to provide a path to ground for the knocker, typically called the solenoid drive.]] 
Here I've stuffed another wire (purple with black tracer) on top of the solenoid 8 drive connection at J8, pin 9. This wire will eventually be connected to the non-banded side of the knocker coil.
 

[[File:SegaKnockerInSitu.jpg|thumb|left|300px|The new knocker, screwed to the cabinet upper left corner...not much room there. Also add the "strike plate" to the cabinet side.]] 
Of course, you need to procure the actual knocker hardware, and connect it as shown in the prior pics. In the picture at left, we've added a Sega knocker assembly and strike plate.
 

The last thing to do is to enter the game adjustments and turn the electronic knocker sound and the European Token Dispenser settings to off. On Starship Troopers, Enter Portals, Adjustments, Sega, and then adjustment 33 (Knocker Volume - set to OFF) and adjustment 40 (European Token Dispenser - set to OFF).

That's it. Enjoy those knockers!
 

===Flasher problems===
[[File:SSTFlashers.jpg|300px|left|thumb|One of the 4 sets of 4 colored flashers on Starship Troopers.]] 
Starship Troopers, Apollo 13 and perhaps other White Star games, drives 4 flash lamps via a single TIP-122 transistor. The TIP-122 is rated for a maximum drain of 8A (and a working current of 5A) while 4 flash lamps typically have a cold resistance of under 1 ohm (0.8 ohm is typical including wire and socket resistance.) While incandescent lamps only present their minimum resistance when extinguished (they are negative-temperature coefficient devices by design) the surge drain when these lamps are lighted radically exceeds the transistor's rating and is likely to damage or destroy it over time.

These channels should be replaced with TIP-102s (15A peak drain) or replace two (or more) of the flash lamps with LEDs to bring the drain in-line with the maximum ratings of the TIP-122.
 

===Controlled lamp problems===

==== Overview of The Lamp Matrix ====

The WhiteStar lamp matrix is an 8 column, 10 row lamp matrix, powered by 18V.

Lamp matrix power is derived from 13VAC presented to the I/O Driver board at J17, pins 8 and 9, via the transformer secondary winding. The circuit is fused by F22, an 8ASB fuse. BRDG20, a 35A bridge rectifier creates the 18VDC which is then smoothed by two 15,000uf/25V filter capacitors at C201 and C202. Of interest is the combined filtering of 30,000uf matches the original lamp matrix filtering capacity of old Williams System 3 games. When lit, LED202 indicates the presence of 18VDC power.

A blown fuse at F22 probably indicates a shorted bridge at BRDG20.

[[File:WhiteStarLampMatrixComponents.jpg|300px|thumb|left|Components of the WhiteStar I/O Driver Board Lamp Matrix]] 
Lamp rows are implemented with STP19N06L or STP20NF06L FETs, controlled by the 74HCT273 at U6 on the I/O Driver Board. 39K current limiting resistors protect the 74HCT273 from sinking too much power. The 74HCT273 is strobed (enabled) via the LMPSTB which originates at U205 (a 74LS138 at U205, pin 15).

If a STP19N06L (or STP20NF06L) transistor fails, it can be replaced with an IRL530N or an IRL540N. However, using an IRL530/540 has been known to create "ghosting" or "always dimly lit" behavior in the lamp row. If the original part can be obtained, this possibility can be eliminated. An IRFnnn (i.e. IRF530) or BUZ22 can not be used as a replacement.

Lamp columns are implemented by the obsolete VN02N PENTAWATT solid state relay (5 legs). They are controlled by the 74HCT273 at U18 on the I/O Driver Board. 18VDC is "strobed" to the lamp column headers. The 74HCT273 is strobed (enabled) via the LMPDRV which originates at U205 (a 74LS138 at U205, pin 13).

A replacement for the obsolete VN02N has not been identified. In addition to the WhiteStar I/O Driver board, VN02Ns were used on Capcom driver boards.

Be sure to check the fuse clips for the controlled lights. They go bad from either metal fatigue or they crack. This causes poor, erratic, or no connection with the fuse and thus, no lights.
 

===General illumination problems===

The four general illumination (GI) strings are turned on and off via the relay on the power driver board. On the White Star board the relay is controlled via transistor Q200 and latch U206. This is more or less the same setup found in earlier Data East and Williams System 11 games where the relay is located on the power supply or PPB board. These relays seldom fail. The part number for the 24VDC relay is any of the following:

*LB2-24DP (Great Plains Electronics number)
*190-5002-00
*LY2-0-DC24
*FRL264 P024/02CK
*R14-11D10-24P

If one or more GI strings are out check fuses F24 to F27 and then connector J15. Although WhiteStar GI connectors don't burn and tarnish like early Bally/Williams WPC GI connectors, checking both the male and female connectors at J15 is worthwhile.

[[File:Sega-whitestar-pdb-gi-error.jpg|300px|left|thumb|A leaky capacitor at C32]] 
If the GI goes out during game play and turns back on when opening the door, check capacitor C32 on the power driver board. It normally has nothing to do with either the GI circuit or the relay voltage but a leaking cap can short the trace coming from Q200 to ground. In this case the relay pulls in and disconnects the GI. When you open the door the game cuts the coil power for the relay coil and the GI turns back on. This has been observed in a Twister game.

The fuse clips for the GI circuits can fail, either by cracking or by losing their springiness.
This causes poor or no contact with the fuse and intermittent or no power to the associated GI string of lamps.
 

=== Switch problems ===

==== Overview of the Switch Matrix ====

The WhiteStar switch matrix is the typical 8 by 8, 64 switch matrix. As with other switch matrix implementations, isolation diodes are used on every switch in the matrix.

Switch columns (strobes) are connected to CN5 on the top edge, left side, of the CPU/Sound board. The columns are controlled by the 74HCT273 at U203 which sequentially controls an array of 8 2N3904 transistors. These transistors switch the 5VDC, normally held high via 560 ohm pull up resistors R423 through R430, to ground.

If a switch in the matrix is closed, the ground driven through the switch column will be presented at the row associated with the column/row intersection of that switch.

Switch rows (returns) are connected to CN7 on the top edge, right side, of the CPU/Sound board. 5VDC pull up resistors (560 ohms at R401 through R408) normally hold the switch row high. However, when the ground is presented at the row header of CN7, that 5VDC is pulled to ground. The signal is compared to 5VDC by the LM339 comparators at U400 and U401 with the result presented the the 74HC245 at U205 and then read via the 68B09E's data bus.

Note that the WhiteStar LM339 comparison implementation differs from the Bally/Williams WPC implementation which also uses 5VDC as a comparison voltage (reference) but compares that 5VDC to either 12VDC (open switch) or ground (closed switch).

==== General Switch Matrix Testing ====

[[File:WhitestarSwitchTest.jpg|thumb|300px|left|Testing Whitestar CPU/Sound board switch matrix circuitry with a jumper. A diode is not necessary.]] 
Like most modern game manufacturers, Sega/Stern games employ a switch matrix. The switch matrix circuitry on the CPU/Sound board may be tested (as pictured at left) by jumpering between switch row and switch column header pins while in switch test. This works with all versions of the Whitestar CPU/Sound board.

Note that some games, that do not use the full switch matrix, will fail to report a switch closure when jumpering row and column header pins for a switch that is shown as "not used" by the game. i.e. Sopranos does not use switch column 6. While a strobe is sent out on column 6, jumpering between column 6 and any row will not return a switch closure indication in switch test.

 

==== Playfield Switch Problems ====

===== Modular Stand Up Targets =====
The following Sega games employ unique playfield "Stand Up" targets:
*Goldeneye
*Twister
*Space Jam
*Star Wars Trilogy
*The Lost World Jurassic Park
*Starship Troopers
*Viper Night Drivin'
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park
*Playboy (used behind the "Peek-A-Boo" stand up)

They are self-contained modular targets, made by Happ Controls, that are quite easy to remove or replace. The target "faces" may be purchased separately and may be interchanged easily. The unit has a self-contained diode, like all switches that are sensed via a switch matrix. It also contains a small micro-switch, that the "tail" of the target face actuates. The "Achilles Heel" of this target system is the IDC connector. As with all IDC connectors, the wires can pull out fairly easily. 

Detailed disassembly / assembly instructions can be reviewed in [http://www.pinwiki.com/wiki/images/7/76/Stern-Sb110.pdf Stern Service Bulletin 110]. 

<center>
<gallery widths=250px heights=200px perrow=3 caption="Sega Modular Targets (from Starship Troopers)">
File:SegaTargetFullyAssembled.jpg|<center>An example target. The target "faces" are interchangeable.</center>
File:SegaTargetParts.jpg|<center>"Exploded" target parts. The gray switch part must be oriented correctly. Note the integrated diode just under the micro-switch, center/bottom.</center>
File:SegaTargetIDCConnector.jpg|<center>The Achilles Heel of a Sega target...the IDC connector.</center>
File:SegaTargetDisassembly.jpg|<center>The first step to disassemble a target. Slide the rear face of the target assembly up.</center>
File:SegaTargetTestingZero.jpg|<center>Testing a closed target switch, step 1. In diode test, with the switch closed, your meter should read 0 or null.</center>
File:SegaTargetTestingDiodeDrop.jpg|<center>Testing a closed target switch, step 2. In diode test, with the switch closed, your meter should read .5 to .7, the nominal voltage drop across a diode.</center>
</gallery>
</center>
 

=====Magnetic Reed Switches=====

[[File:Placeholder.jpg|thumb|300px|left|Sega Magnetic Reed Switch (from Space Jam)]] 
Starting with Space Jam, Sega introduced magnetic reed switches. This type of switch is a sealed, non-serviceable switch. Theory of operation of the reed switch can be reviewed in [http://www.sternpinball.com/upload/downloads/sb89.pdf service bulletin 89]. Replacement part number is 180-5145-XX.
 

=====Ball Trough Switch Problems=====
[[File:White Star Trough 18 Nut.JPG|left|thumb|300px|Typical Sega ball trough assy. using 1/8" screws heads]]
[[File:White Star Trough 316 Nut.JPG|right|thumb|300px|Typical Stern ball trough assy.using 3/16" screws heads]] 
As with any sub microswitch, the switches can become sporadic or fail over time. Another thing that can happen is the switch arm can break at its pivot point. This happens with this style of switch more frequently than other styles, because the metal arm is placed between two plastic ears. With nearly every other style of sub microswitch, the arm has the metal ears which go over plastic nubs on the switch body. The correct replacement switches are 180-5119-00 roller arm switches. Over the years Sega / Stern used both 1/8" and 3/16" screw heads on the screws which secure the trough switches. At this time, it is uncertain when Sega / Stern changed the screw size. 

[[File:Xcelite 18 Nutdriver.jpg|left|thumb|300px|Xcelite 1/8" Nutdriver used to remove screws from trough switches]]
[[File:DE Ball Trough Divots.JPG|right|thumb|300px|Ball trough assembly with divots. Although it's not a White Star game, Jurassic Park is used for this example.]]
There may be other issues, which appear to act like ball trough switch failures. One of the problems is divots in the ball trough itself. After many iterations of the balls slamming into the trough over and over, divots start to develop. This divots can keep balls from rolling down the trough assembly. In turn, the balls will not be closing the proper switches in the trough. The end result is a game that "loses its mind". If the balls are not where they are expected to be in the trough, the game cannot function as intended. 

A similar issue to divots in the trough is magnitized balls. This occurs primarily in games where a magnet captures a ball and holds it for a length of time. Some examples of games with magnets that hold the ball are Apollo 13, Goldeneye, Twister, Space Jam, and X-Files. This problem typically happends when two or more balls are grouped together in the trough. They will literally be held in place and stick to the trough. This happens to the balls located furthest from the ball trough VUK. To determine if a ball or balls are magnetized, remove the lower apron, and the top bracket over the trough. Gently place a non-metallic object between the balls to see if they separate themselves.
 

For ball trough switch issues pertaining to the opto boards, see the section [[#Two_Balls_Served.2C_Continuous_Balls_Served_to_the_Shooter_Lane.2C_or_the_Trough_VUK_Fires_Repeatedly | below.]]
 

====Opto Switch Problems====
With White Star games, opto switch pair closures are analyzed by the CPU in the same manner as leaf switch pairs or normally open (NO) microswitches. When a leaf or NO microswitch closes, the end result is identified by the CPU as a valid switch closure.

[[File:Sega_X-Files_Optos.JPG|left|thumb|300px|Two sets of opto pairs installed in a Sega X-Files ]]
If an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch.

The transmitter side is an ultra-red LED with a current limiting resistor. The receiver is an identical ultra-red LED. When light from the transmitter shines on the receiver LED, a small amount of voltage is "excited" in the LED. By using discrete components on the receiver side, that small voltage is detected and the appropriate signal is sent to the CPU via the switch matrix return (row). In this design, failure on the receiver opto side is more common. The transmitter LED will be lit (and visible with the naked eye), while the receiver LED will not be lit.
 

<center>
<gallery widths=300px heights=150px perrow=3 caption="Sega/White Star Transmitter, Receiver, and Opto 'Long Hop' Board Pair, as found on Starship Troopers. Note that the ultra-red LED on the transmitter side is not lit until power is applied. The receiver side never illuminates.">
File:SegaOptoTransmitter.jpg|<center>The opto transmitter side.</center>
File:SegaOptoReceiver.jpg|<center>The opto receiver side, with accompanying electronics. The red colored LED is a diagnostic aid to indicate a detected switch closure.</center>
File:SegaOptoAlignment.jpg|<center>An opto pair. The pair must be in perfect alignment or the opto switch will operate unreliably.</center>
</gallery>
</center>
 

This particular system is different than how Bally/Williams WPC CPUs handle opto pairs. WPC games employ infrared opto pairs.

Theory of operation for these circuits is described in the manuals. Sega/Stern have included some excellent, detailed, technical documentation within their manuals. [https://www.pinwiki.com/wiki/images/9/92/Sb67.pdf Stern Service Bulletin #67] includes detailed theory of operation of these opto switches. 

=====Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly=====
Common problems with some White Star games are:
# Two balls are served to the shooter lane.
# Balls are continuously served to the shooter lane.
# The trough VUK repeatedly fires, when there are no balls above the VUK trough plunger.

The first test is to determine if the balls are sliding down the trough. If they are repeatedly magnetized they tend to stick to the side of the trough and not slide down. Replacing the balls with will fix this. There are balls available which are low magnetic, but you can also line the floor of the ball trough with a thin sheet of PETG breaking the magnetic contact.

Depending on the exact circumstances, and the era of the White Star game, one or two of these symptoms can occur. The crux of the problem is either one or both of the two trough LED opto transmitters or receivers is failing. Rarely do the components on the trough opto boards other than the red LEDs actually fail though. And in most cases, it is not the LED itself, although, there are some instances when the problem is a failing LED. It is noteworthy that the issue is more common to the opto receiver side more so than the opto transmitter side. 

[[File:Stern WS test trough 1 in trough.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough]]
[[File:Stern WS test trough vuk up one ball.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough and One Ball Stacked]]
If the any of the previously mentioned symptoms are evident, the best approach is to first put the game into "Clear Ball Trough" mode via the Portal buttons on the coin door. Consult the manual documentation for details how to enter this test. Once all of the balls are removed from the trough, no balls should display on the DMD display. If either of the two images shown to the left are displayed on the DMD, and the ball trough no longer has any balls present, there is a problem with either the transmitting or receiving opto boards.<br=clear all>

The first thing is to observe the two red opto LEDs on the transmitting board. This board is located on the backside of the ball trough. If the transmitting LEDs are lit, there probably is not a problem with them. However, this is not always necessarily the case. Secondly, inspect the opto LEDs on the receiving board. To do this, the game will have to be turned off, and the receiving opto board removed via the three screws which attach it to the trough. Look for hairline cracks around the .100" angled header pin solder joints. Likewise, inspect the solder joints around the opto LEDs. If cracks are evident in any of these locations, remove, and apply fresh solder to these connections. Reinstall the receiver board, and observe the results. Conversely, if hairline cracks are not found, or if the same symptoms are still evident after reflowing solder joints, replacement of the LED optos is suggested. 

White Star games initially used MT5000UR ultra-bright red LEDs, while later games used TLRH180P ultra-bright red LEDs for both the transmitter and receiver boards. Both styles of LEDs have become expensive and fairly difficult to source. Great Plains Electronics offers the [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] as viable replacement for either original, factory LED. The only caveat is that both the transmitter and receiver opto LEDs must be replaced in pairs to ensure proper function. 

When replacing the opto LEDs, make certain the base of the LED is placed squarely on the PCB. An LED which is poorly installed may result in sporadic switch closures. 

[[File:DE Trough Ball Lock3.JPG|300px|left|thumb|Lock Ball Assembly (from Jurassic Park - used for illustrative purposes)]] 
Please note that a "Lock Ball Assembly" was employed in the trough design on early White Star games. The lock ball assembly is a unit, which was carried over from later Data East and early Sega games. It consists of a coil mounted horizontally above the left side of the trough VUK. This assembly was later removed presumably either due to cost factors, or so this coil assignment could be used as a playfield coil feature elsewhere instead. 

If a lock ball assembly is used in the game, and trough opto failure has occured, the symptom will more than likely be that the trough VUK will fire repeatedly without a ball present above the VUK plunger.
 

=====Phantom Opto Switch Closures=====

Similar to the discussion above, "Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly", other opto pairs in the game may fail over time and become unreliable. Usually this manifests as phantom switch closures. Games like Starship Troopers that use an opto pair for both the left and right orbit shots may score the orbit shot randomly or even continuously. If the "long hop" opto assembly is removed, you may find that the opto pair registers correctly if the optos are aimed with great accuracy at one another. However, the slightest misalignment (like flexing the PCB) will cause the opto pair to register a "hit".

The correction for this is again to replace the original MT5000UR or TLRH180P ultra-bright red LEDs, with [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] LEDs from Great Plains Electronics.
 

===Display problems===
A few of the many possible display problem root causes are...
*Failure in high voltage power supply
*Failed Dot Matrix Display
*Failed ribbon cable
*Failed power connector on display driver board
*Failed 74LS374 buffer IC on the MPU board

Each possible root cause is discussed below.

==== Measuring High Voltages for the DMD Display ====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|300px|thumb|left|Testing DMD Controller voltages at the display. Note: This picture is a Williams game, but the concept is the same.]] 
To test for the voltages necessary for the DMD to operate, first open the backbox, and rest the DMD panel face down on the glass. Or, if the game has a "Showcase" style head (i.e. StarShip Troopers), swing the panel open to gain access to the HV connection to the DMD. The simplest place to test the voltages is at the display end of the power wire bundle as shown in the picture. SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you! 

The dot matrix display needs three voltages to operate, nominally -112, -100, and 62 VDC. All three voltages must be present for the display to operate correctly.

Place the black lead of the DMM under the ground braid in the game's head or use clip leads to secure the black lead to ground. Remember, you are working one-handed, so this becomes a necessity. Place the red lead of your DMM on each of the pins supplying power as shown in the picture. As long as there is a 12VDC difference between the Anode and 12VDC offset voltages, your DMD controller is providing correct voltage levels.

{| class="wikitable"
!Function
! Pin 
! Spec 
! nominal voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>-120V</center> || <center>'''-112V'''</center> ||
|-
|  12VDC Offset  || <center>2</center> || <center>-100V</center> || <center>'''-100V'''</center> ||  Must be 12V less than anode voltage. Will be about 20V less than anode voltage if display not connected
|-
|  Key || <center>3</center> || || ||
|-
|  Ground || <center>4</center> || || ||
|-
|  Ground || <center>5</center> || || ||
|-
|  5VDC || <center>6</center> || <center>5V</center> || <center>'''5V'''</center> ||
|-
|  12VDC || <center>7</center> || <center>12V</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>60V</center> || <center>'''62V'''</center> ||
|}

If the high voltages are off by more than a few volts, turn the game off, disconnect the power connector at the HV Power Supply, and test the voltages at the HV Power Supply male header pins. If the voltages return to nominal values, the zener diodes on the power supply are probably OK but the resistors and transistors around them are suspect. As shown in the table above, if HV power is not connected to the display, the nominal 12VDC offset will be about 20VDC.

Note that a failing or failed DMD display glass can drag these voltages down. Before you begin any work on the HV Power Supply board, perform the above test with the DMD display power disconnected. If the voltages return to nominal values, it's possible that your display is the culprit. Test the high voltages with a known good display to isolate the fault to either the HV Power Supply or the display panel.

Should your HV Power Supply fail, the circuit is almost identical to the circuit used by Williams in their WPC DMD Controller. Similar parts are required to rehab the Sega/Stern HV Power Supply.

As of April 2014, schematics for the HV Power Supply are no longer available on Stern's site.

====Typical Failures of High Voltage Power Supply====
[[File:Stern WS DMD PSU.JPG|right|thumb|300px|A Stern 520-5138-00 Dot Matrix High Voltage Power Supply]]

'''The nominal output voltages of this board are shown below.''' 
The voltages measured between game ground and each pin of CN2 (right side as installed in the game).
*-110V on CN2-1
*-98V on CN2-2
*+5V on CN2-6 (piped directly through from CN1-7. This was a method of minimizing connector complexity)
*+12V on CN2-7 -- 20V is supplied at CN1-6 and is regulated down to +12V by VR1, a 7812. Note: the voltage at this pin will be missing if the board isn't stuffed with the 7812. It is not known when Stern/Sega stopped stuffing this location.
*+68V on CN2-8

The fuse on the board is a 3/4 ASB fuse.

'''Common failures:'''

*Fuse blowing
*-110V missing or too low
*-98V missing or too low
*+68V missing or too low

'''Solutions:'''

A blown fuse is indicative of a failed rectifier diode at D1 or D2 (1N4004. Anything from a 1N4005 to a 1N4007 can be used too). When D1 fails, Q1 and Q3 often fail along with it. When D2 fails, Q2, Q4, and Q5 often fail along with it.

*-120V problems are often caused by a failed transistor at Q2 (MPS-A42) and/or Q4 (MJE15031). When one of the transistors fails, often the other one fails too. Replace zener diode D4 (3.9V, 1N4730), D6 (100V, 1N4764A) and D7 (13V, 1N4743A) as well.

*-100V problems are often caused by a failed transistor at Q5 (MJE15030) or zener diode D6 (100V, 1N4764A). It's best to replace both. The 2k/5W resistor on R8 might also be the problem source, mostly due to failed solder contacts.

*+60V problems are often caused by a failed transistor at Q3 (MJE15030) and/or Q1 (MPS-A92) When one of the transistors fails, often the other one fails too. Replace zener diode D3 (3.9V, 1N4730) and D5 (68V, 1N4760A) as well.

As of 2014, schematics for the display power supply board are no longer available on Stern's website.

The Data East display power section of the 520-5047-01 and 520-5047-02 boards is an almost 1:1 copy compared to the one on this board. 

==== Failed Dot Matrix Display ====

A failed Dot Matrix Display will obviously cause display problems. Once you've tested for proper voltages, swap in a known good display, and swap the suspect display into a known working game. If the suspect display doesn't work in the known working game, it's time for a new DMD display.

==== Corrosion Under Header Pins ====

[[File:DESegaSternDMDControllerCorrosion.jpg|300px|thumb|left|Corrosion under the dual row headers of a DMD Controller board]] 
Corrosion from leaky batteries, being the bane of pinball PCBs, finds it's way to many places that might not normally be suspected. Sometimes, alkaline corrosion invades the header pin carriers, as shown in the picture at left. In this case, enough of the signals between the MPU board and the DMD controller board were corrupted to prevent proper rendering on the DMD display. Cleanup via typical methods restored this board to proper operation.
 

==== Failed ribbon cable ====

The ribbon cables on Sega/Stern White Star games connecting the CPU to the display controller are particularly long and twisted. There is ample opportunity for the ribbon cable to be damaged.

You should reseat the ribbon at both ends several times to knock off accumulated corrosion. This might temporarily solve the issue.

A simple test of the ribbon cable integrity would be to reverse it, causing the conductors used within the ribbon to be "swapped". Remove the ribbon from both ends, and instead of seating it with the red stripe at pin 1, seat the ribbon with the red stripe at the opposite end from pin 1. Make sure you reverse both ends of the ribbon. If the results witnessed on the display are then different, there is a good chance you need a new ribbon cable.

Gently bending and twisting the ribbon cables may help uncover intermittent connections and a compromised cable. Don't bend/twist too vigorously as this in itself may compromise the cable.

==== Failed power connector on display driver board (CN2) ====
[[File:CN2.jpg|300px|thumb|left|The '''craptastic''' 3 pin DMD Controller power header at CN2.]] 
Sega/Stern (and even Data East) made a poor decision for the power connection to the display controller. CN2 is a .156, 3 pin connector, which connects 5VDC and Ground to the display controller. The connector can be installed upside-down and reverse the 5VDC and Ground connections. This may kill the ROM chip and other chips on the board.

The solder joints for these header pins fracture often, or the pins in the female housing lose their grip (and hence connection). It is good practice to repin both sides of this connection, using crimp-on TriFurcon pins in the female housing.
 

==== Blank Display After "Splash Screen" Or Unusual Messages (Failed 74HCT273 buffer IC on the MPU board) ====

[[File:BadSchematicTableIndex.jpg|300px|thumb|left|One manifestation of a failed U201 or an open between U201 and the plasma display connector. Image courtesy of Chris Hibler.]]
The 74HCT273 at U201 on the CPU board buffers the output to the display controller via the ribbon cable. Should this IC fail, incorrect or no data will reach the display controller. Most of the time, this results in only the "splash screen" appearing which is displayed by the DMD controller on it's own, or in rare instances, the odd displays shown at left. First an over-scaled "Location ID:" image is displayed then "Bad Schematic Table Index!". This particular failure was caused by a corroded trace between U201 pin 2 and the via just northwest of pin 2. However, the same message may be displayed any time that the data path between U201 and the DMD Controller fails (i.e. poor header connections, failed ribbon cable).

U201 can be tested with a DMM following the process described [[General#Testing_an_integrated_circuit| here]].
 

====Display Issues Caused by Mismatched Game and Display ROMs====
[[File:WhiteStarEffectF7.jpg|300px|thumb|left|This message appears when the display controller software can't correctly decode display "calls" made by the MPU. Note that hexadecimal numbers other than "F7" may be displayed. Image courtesy of Chris Hibler.]]
Over the course of a game's manufacturing run, and even post production, game and display software was updated. It is important to ensure that the game ROM version is compatible with the display ROM version. Newer versions of the game code may request a display routine from the display controller that the display controller can not make sense of. When this happens, the display controller will display "Effect NN", where "NN" is the hexadecimal number of the display routine received.

Note that a less likely failure of IC U17 (a 74LS245) on the display controller board, which buffers inputs from the MPU, can cause the same or similar behavior. Corrosion on the ribbon header pins (both ends) or a faulty ribbon cable are other possible reasons for this message.
 

===Sound problems===

Before going any further, check all of the basics in the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section. 

'''Basic operation (simplified) of the White Star CPU/Sound board audio part:'''
The main CPU (U200) makes sound calls to the sound CPU (U6) which instructs the BSMT to play a certain sound. The BSMT fetches the required data (sound sample) from the ROM memory (U17-U21-U36-U37) and feeds the 16-bits wide parallel data to a conversion circuit which makes it serial data (shift register, U23-U24). The serial data is fed into a DAC (U26, Digital to Analogue Converter) that outputs to a pre-amplifier (U30, OPAMP). The output from the pre-amplifier is fed into the TDA2030A amplifiers at U101/U102 and sometimes U100 (some boards have 3 amplifiers, one for each speaker) and from there the audio signal goes to the speakers.

[[File:XilinxCPLD.jpg | thumb | right | 300px| The XC9572XLT Complex Programmable Logic Device. The yellow paint spot indicates that it has been programmed.]] 
The White Star (modified) version of the MPU board replaces almost all of the prior version's sound circuitry with 3 surface mount ICs.
*Xilinx CPLD at U414 (XC9572XLTQFP, T indicating the 100-pin version, QFP indicating Quad Flat Pack)
*Atmel RISC processor at U402 (AT91R40008)
*Atmel flash memory at U8 (AT49BV162AT)

The Xilinx CPDL ([https://en.wikipedia.org/wiki/Complex_programmable_logic_device Complex Programmable Logic Device]) is programmed by Stern (or it's board manufacturer) via the [https://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] connector on the board.

The Atmel RISC processor ([https://en.wikipedia.org/wiki/Reduced_instruction_set_computing Reduced Instruction Set Computing]) replaces the 68B09EP of the prior board.

The Flash Memory contains the Sound Operating System. The correct version of the sound operating system my be "flashed" into the memory.
LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin #157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another). In April, 2016, "Chas" at Stern Pinball noted that sound operating system 8 (O/S 8) is backwards compatible with all WhiteStar (modified) games. It may even work with sound ROMs predating the WhiteStar (modified) board. However, there are known compatibility issues with early WhiteStar Sega games like StarShip Troopers.

The sound section of both board versions is quite reliable. The failure occuring most is a failed TDA2030A amplifier. If a sound problem can be isolated to one of the three fine pitch surface mount ICs on the WhiteStar (modified) board, the only option known as of April, 2016 is to return the board to Stern for repair. Stern does carry the parts necessary, but removal and replacement of such fine pitch parts is above the capability of most pinball hobbyists.

'''Sound missing from one of the speakers:'''
Possible failed TDA2030A amplifier.

'''No sound at all:'''
Check the voltages on the board. On the DC input connector CN2 there should be approx. +12V DC between pin 2 (ground) and pin 6 (+12V) and -12V between pin 2 (ground) and pin 3 (-12V), these voltages come from the Power Supply Board. On the board itself are two voltage regulators to convert the +12V and -12V to +5V and -5V for the pre-amplifiers, check these voltages by measuring between the ground (GND test point) and U30 pin 8 for +5V, U30 pin 4 for -5V.

Other causes of no sound at all are the U7 game ROM being corrupted or improperly seated. You can re-seat this ROM and it often solves the issue. If any of the voice ROMs (U17, U21, U36, U37) are corrupted or improperly seated, the sound will still work but will be corrupted or have intermittent issues such as scratchy sounds or improper sounds at specific times.

An incorrectly jumpered or installed RAM chip can also cause no sound. JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket).

Finally, if you have no sound at all, check that you have the correct sound board. Some operators may have swapped the Atmel based board with a BSMT2000 based board board for the older series White Star games. The Atmel based board will work in all White Star systems although some sounds may not be rendered correctly or at all. The BSMT2000 based board will work but will present no sound at all in all games newer than lord of the rings (2003).

'''Samples playing randomly'''
This happens on Whitestar (modified) CPU boards that emulate the BSMT2000 (which Stern could not source cheaply enough at the time). Reflashing the sound operating system firmware per Stern [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin 157] is recommended.

'''Sound is distorted'''
If the sound is distorted, a prime suspect is the TDA1543 (U26) chip. This sounds as if the volume is very over modulated and are “clipped”. Be sure to use the TDA1543 version and NOT the TDA1543A. The TDA1543A uses another protocol (Japanese). If the sound is distorted at master volume levels below 4, see the [http://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#Loud_Hum_and_.2F_or_Distortion_at_Low_Sound_Levels "Loud Hum and/or Distortion at Low Sound Levels"] section below.

'''Sound cuts out at the exact same point in a clip every time'''
If the sound consistently cuts out, or volume is lowered, or the clip is muffled, every time at the same point in the clip, there is a possibility that the 6116 RAM at U4 has failed.

'''Sound volume is extremely loud'''
Possible TDA1543 (U26) chip failure or counterfeit chip.

'''Loud hum'''
If there is a loud hum coming out of the speakers as soon as the game is turned on, make certain that the +12V is present.

'''Loud hum/burnt speakers/12V DC coming out of the speaker connector'''
If you have a machine with all speakers dead, check for voltage on the speaker wires. If the -12V wire from the driver board to the CPU board is disconnected, it can cause 12V DC to be sent down the speaker line, causing a loud hum and fairly quickly destroying any speakers connected!
 

'''Music Sounds Like Alvin and the Chipmunks'''
[[File:WhiteStarW6JumperLocation.jpg|left|thumb|300px|Schematic diagram showing the physical location of jumper W6 between the sound section 68B09E and the BMST2000, enabling the use of 8Mb EPROMs]] 
The original WhiteStar schematics mention jumper W6, which "must be installed for games that use 8Mb Sound EPROMs (U17 U21 U36 U37). For games which use 4Mb Sound EPROMs this jumper is not installed but 4Mb EPROMS will work on boards with W6 installed". This boils down to...install jumper W6. The manifestation of using 8Mb ROM images on a board with W6 not installed is sound that appears to be "Alvin and the Chipmunks"-like.

[[File:YT.png]] A YouTube video showing an incorrectly jumpered WhiteStar MPU with Harley Davidson ROMs can be found [https://youtu.be/7MXxngST5g4 here].

Note that the WhiteStar (modified) MPU board does not provide jumper W6, nor is it needed. The WhiteStar modified board works with both 4Mb and 8Mb sound ROMs, as if W6 was installed.
 

====Sound Section Jumper Settings====
JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket). An incorrectly jumpered or installed RAM chip can result in no sound at all.

'''Important:''' Under normal operation...
*JMP2 should be on the right pair of pins
*JMP3 should be on the top pair of pins, and
*JMP4 should be on the bottom pair of pins.

Placing the jumpers in any other position will cause sound to be missing. These jumpers are provided to update the sound operating system within the flash memory at U8.
 

====Loud Hum and/or Distortion at Low Sound Levels====
[[File:SternServiceModForLowSoundLevels.jpg|300px|thumb|left|Trim POTs connected across R106 and R110. This mod was offered by an aftermarket seller. Image courtesy of Jack Jarrett]]
[[File:WhiteStarResistorHack.jpg|300px|thumb|right|Trim POTs connected across R106 and R110 in a rather kludgy way...but it works. Image courtesy of PinSider Capt_Pinball]] 

Stern released [http://www.sternpinball.com/upload/downloads/sb133.pdf Service Bulletin 133], which discusses a fix for a loud hum and / or distortion when the master volume is set below level 4. The machines that are specifically effected are Monopoly and Austin Powers. However, it has been over 10 years since these games have been released, and boards get transplanted to other games over time. So, it is important to check the two resistors (R106 and R110) in the amplification section of the CPU / sound board to see if the correct values are installed, regardless of the game. The correct resistor values should be 33K ohms 1/4 watt for R110 (ORG-ORG-ORG-GOLD), and 10K ohms 1/4 watt for R106 (BRN-BLK-ORG-GOLD). Consult the service bulletin for more details, and the layout of the amp section. The R106 and R110 control the analog volume. When these resistors are broken (open) the analog volume goes to 100% and can't be controlled via the buttons (digital volume) on the coin door. The higher the resistor value the higher the volume.

Another method of accomplishing the same thing, without removing and replacing a resistor, is to add a resistor to the back of the board, across R106 and R110, creating the equivalent resistance as mentioned above. A 4.7K resistor seems to be a sweet spot.

Yet another method used is to clip a 10K trim pot across each resistor as shown in these images. The trim pot can be adjusted to a good compromise between hum and volume.
 

==== Low Background Sound Volume ====
[[File:WhiteStarBackgroundSoundVolume.jpg|300px|left|thumb|Background sound level setting on Roller Coaster Tycoon]] 
Some games, at least Viper Night Drivin' and Roller Coaster Tycoon, provide a means of adjusting the level of the background sound. The sound can be adjusted from level 1 (loudest) to level 15 (lowest).
 

====Adding a Second Backbox Speaker to some Sega Games ====
[[File:NewSpeakerAndSpeakerBlank.jpg|300px|left|thumb|Adding a second backbox speaker may improve the sound in games shipped with a single backbox speaker. Buy the speakers in pairs. This image shows the new speaker installed onto the left speaker bracket, and the right speaker position "blank" from a StarShip Troopers game. The "blank" must be modified so that the new speaker can be attached.]] 
A chap named Martin Riley submitted a nice article to the PinballNews explaining how to add a second backbox speaker to games like StarShip Troopers.

From the article... 
"Mid-life Sega games from Twister through to and including Viper Night Drivin' only had the left hand backbox speaker plus the cabinet speaker and only two of the 3 audio amps are populated on the CPU board.

Late Sega games from Lost in Space onwards have two backbox speakers but they are effectively mono as they are both connected to the left channel audio amp on the CPU board (the right channel amp being unpopulated)."

The complete article can be found at http://www.pinballnews.com/learn/speaker/index.html

The article lists all components required to add the 3rd speaker channel. Some (maybe all) two channel boards are not stuffed with C122, which is not listed in article parts list. You'll need one more 0.1µF axial ceramic capacitor for C122.

Adding a 3rd speaker to StarShip Troopers improved the sound quite a bit. The sound is richer and cleaner. The emphasis on some sounds is more pronounced and easier to hear. Edit: months later, I was testing a board in my StarShip Troopers that didn't have the 3rd amp. Forgetting that I had added the 3rd amp to my MPU, I initially thought something was wrong with the sound that the MPU under test was producing. It was merely the difference between a single and dual backbox speakers.

Mounting the additional speaker to the "blank plate" (as found in StarShip Troopers) required drilling the rivets that attach the speaker grill, and replacing them with low profile head screws. This is only necessary for Sega "Showcase" backbox games. For games like Independence Day, mounting the additional speaker should be trivial.

 

==== Is a Second Backbox Speaker Really Worth It? ====
While some have reported good results adding a third amp and second backbox speaker to these early Sega games, there are questions about the efficacy of such a solution. While better speakers themselves will improve the sound, the game-specific sound samples in the ROMs are mastered as mono sound clips. There are very few sounds in the game that are true stereo sound and these are usually simple sound effects which were used in multiple games. 

You can listen to and judge for yourself by running the Bridge front end and the M1 MAME music player. Bridge and links to the M1 player can be found [http://www.e2j.net/downloads.html here]. 

The mono mastering continued through the White Star II and SAM systems. As David Thiel, who has created music and sound for numerous Data East and Stern pinball machines, states on this [http://daudioguy.multiply.com/video/item/5/Family_Guy_Stern_Pinball_Music_and_Sound_Effects_by_David_Thiel?&show_interstitial=1&u=%2Fvideo%2Fitem page] of his website, he "composed, arranged, performed, mixed and mastered (all the music for Family Guy) for 24 kHz 16 bit Mono." 

===Flipper problems===
====Non-Functioning Flippers====
====Weak Flippers====
=====Progressively Weak Flippers=====

==Game Specific Problems and Fixes==
'''Lord Of The Rings''' 

If your Balrog stops registering hits, a little checking will sort it out. The mini microswitch with a roller arm used to register hits may need adjusting. Known past problems are a flaky or bad switch, and/or wiring. The Balrog moves in such a way that wires can break inside where you can't readily see them. It's easy to check the switch and wires with a meter. The wires push into an IDC connector nearby; be sure they are pushed in tight.

There isn't any adjustment for the micro switch, except for bending the blade with the mini-roller; try bending the blade outwards slightly. According to the manual, sw #28 stays normally closed and then a Balrog hit opens the switch. This is not the normal target arrangement. So using the Balrog test mode in diagnostics, the switch should stay solidly closed, and then only open when Balrog is tilted forward.

'''The Shire and Gimli VUK switches.''' 
These get hammered on LOTR and will eventually need replacing, There isn't any easy solution other than replacing the flaky switch. The tiny black screws on the Stern switches are 3/16". You will need a nut driver that size if you want to attempt replacement of the switches.

The Shire (and Gimli) VUK switch, are fork blade microswitches. Stern part number 180-5116-01. 
Spec on side of switch says Cherry .1A 125v E63. Try parts4pinballs.com or your favorite Stern parts supplier.

The Shire VUK. 
It's easiest to remove the entire Bottom Left VUK coil and bracket from under the PF (playfield) to change the fork switch. 
Take out the two largest bolts first, using a cross-head (phillips) screwdriver on the top and 11/32" nut runner (or socket) on the bottom. 
Remove the metal VUK arch from the top of the playfield. 
Remove the two lower wood screws (1/4" drive) leaving the one on the corner near the T-nut. 
Supporting the Coil Bracket, remove the last 1/4" screw. 
Unclip the connector from the coil and VUK. Remove coil and bracket assembly. 

Microswitch small screws are 3/16". As stated before, to remove the switch correctly you need a nut driver (or socket) that size.
You should be able to slide the heatshrink tubing all the way up the wires, solder on the new switch and then slide them back down in place. If not, use new heatshrink tubing. Assembly is above steps in reverse. Test in switch tests before replacing assembly and then by throwing a ball in the Shire in attract mode one the assembly has been correctly replaced.
 

'''Ripley's Believe it or Not! and The Simpsons Pinball Party''' 
Not certain what code versions apply with this. When the coin door is open, and the first ball drains, the game will not recognize that the ball has drained at all. Likewise, it will not kick the next ball over to the shooter lane. This is even with the solenoid voltage interlock switch pulled out. It is presumed that the memory lock switch has to be closed for the game to function properly.

This may apply to more games of this vintage other than just these two!
 

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.

*'''Striker Xtreme:'''
**Problem: '''Display is blacked out or only coming on for a few seconds before blanking out.'''
**Cause: Resistors R6 and/or R7 on the display power supply board have gone bad (open or increased in value).
**Solution: Replace resistors R6 AND R7 on the display power supply board. Both are 330k @ 1/2 watt
*'''Simpsons Pinball Party:'''
**Problem: '''When last ball drains, game still thinks its in play.''' Ball search or power cycle will eventually find it.
**Cause: Cracked solder joint on trough board.
**Solution: Pull both trough boards. A 1/4" wrench can be useful in getting the back board off. In this case, the obviously cracked solder connection was on the receiver board in front. But while the board is out, the optos were cleaned with Windex.
**This can be verified by waiting for the problem to show up, then go into switch test. Previously, switch #5 (leftmost) had been suspected and had been re-aligned, but that was probably not necessary.
*'''Starship Troopers, but applies to all:'''
**Problem: '''No display, no sound, upper amplifier went up in smoke.'''
**Cause: Connector CN4 on MPU / Sound board and CN1 of display power supply board were swapped. Both CN4 and CN1 are keyed the same. In haste, these connectors can be mixed up. Keep in mind that the speaker output is a very light gauge wire versus the heavier gauge for the display power supply input.
**Solution: This was not as bad as expected. After studying the schematics, only +20V (CN1 pin 6 - pin 4 is GND on both connections) can potentially backfeed through the sound circuitry. Amplifier U101 failing spectacularly possibly prevented additional damage. Amps U101 and U102 were replaced (U100 was not stuffed on this board). After replacing the amps, sound came back, but was very faint. Further investigation revealed 3 100Kohm resistors had failed, R21, R22, and R24. Also, U26, the TDA1543 DAC, had also failed.
*'''Goldeneye, but applies to all:'''
**Problem: '''Blanking signal OK but driver board blanking LED keeps blinking.'''
**Cause: Ribbon cable from MPU to driver board faulty.
**Solution: Replace ribbon cable.
*'''Goldeneye, probably Twister:'''
**Problem: '''Magnets don't work, MAG2 LED on magnet board keeps blinking in test mode.'''
**Cause: Bad connection from magnet board to magnet between flippers.
**Solution: Fix connection.

Sega/Stern White Star Repair

2023-03-20T21:31:17Z

Jimpal: /* Manuals */

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

==Introduction==

 

==Games==
===Sega===
*Apollo 13
*Goldeneye
*Twister
*Independence Day
*[[Space Jam]]
*Star Wars Trilogy
*The Lost World Jurassic Park
*The X Files
*[[Starship Troopers]]
*Viper Night Driving
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park

===Stern===
*Striker Xtreme
*[[Sharkey's Shootout]]
*High Roller Casino
*Austin Powers
*[[Monopoly]]
*NFL
*Playboy
*Roller Coaster Tycoon
*[[The Simpsons Pinball Party]]
*Terminator 3: Rise Of The Machines
*The Lord Of The Rings
*Ripley's Believe It Or Not
*Elvis
*Grand Prix
*The Sopranos
*NASCAR

==Recommended Documentation==
===Manuals===
The owner's game manual is a handy resource to have for general game operation, game settings & diagnostics, switch & lamp matrices, fuse lists, circuit boards and parts, playfield assemblies, some basic schematics, and wiring diagrams. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended [http://pinwiki.com/wiki/index.php?title=Pinball_Parts_Suppliers pinball parts suppliers]. Some Stern White Star Game manuals are available in PDF form on the Stern Pinball website. They are on the game specific pages of the Stern website. An index of games can be found in the right margin [https://sternpinball.com/support/game-manuals/ here]. 

As of April 2014, the Stern Pinball website no longer archives theory of operation and board schematics in PDF format. 

Be aware that although rare, some factory documentation contains errors in schematics, wiring, switch/lamp matrices, and solenoid assignments.

===Schematics===
Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids.

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===Service Bulletins===
Service bulletins detailed any problems or issues with games that were discovered after they were released.

As of 2014, service bulletins for Data East and Sega games are no longer directly available on the Stern Pinball website, but [https://web.archive.org/web/20130520091730/http://sternpinball.com/ServiceBulletins.shtml can be found on an older archived version of the website].

{| class="wikitable sortable"
|-
!Service Bulletin
!Date
!Game(s)
!Summary
!Notes

|-
|166
|2006, September 20
|Grand Prix & NASCAR
|Trough Up-Kicker Failure
|
|-
|162
|2006, July 11
|The Simpsons Kooky Carnival, MONOPOLY and TITANIC Redemption Games
|Electronic Coin Mech Coin Return Lever Sticks
|
|-
|161
|2005, March 21
|NASCAR / Grand Prix
|NASCAR / Grand Prix Enter/Exit Scoop Modification & 1-Way Gate Bracket Update Kit (502-5048-86); ONLY FOR NASCAR/GRAND PRIX GAMES with SERIAL NUMBERS LOWER THAN <195160 (NASCAR) and LOWER THAN < 19620 (GRAND PRIX) Production Prior December 2006
|
|-
|160
|2005, November 8
|NASCAR
|NASCAR SOFTWARE UPDATE (CPU/GAME ROM U210); ONLY FOR NASCAR GAMES with CPU Version 3.30 or LOWER
|
|-
|159
|2005, August 31
|NASCAR
|NASCAR T-Nut Cover & Target Foam Kit (SPI PN: 502-5042-00), EARLY PRODUCTION GAMES ONLY
|
|-
|158
|2005, August 26
|NASCAR
Early Production Games ONLY
|NASCAR 2-Pin OPTO Ground Connector in Backbox, EARLY PRODUCTION GAMES ONLY
|
|-
|157
|2005, June 20
|Terminator 3, The Lord of the Rings, Ripley's Believe It or Not!, ELVIS, Harley-Davidson 3rd Edition and The Sopranos
|New Version 8 of the Sound Operating System (O/S)* for the White Star CPU/Sound II Board bootFLASH file for EPROM; This new version O/S 8 is compatible with all previous versions of CPU/Snd II ROM’s.

|
|-
|156
|2005, May 5
|The Sopranos
|Cabinet Flipper Switches - Contact Pitting
|
|-
|155
|2005, April 15
|The Sopranos and future Pinball Games
|FYI: Lockdown Assembly & Front Molding Change during the production of The Sopranos Pinball and future Pinball Game Titles
|
|-
|154
|2005, February 20
|Lord of the Rings
|Lord of the Rings Post Upgrade Kit (502-5034-00) ONLY games prior to Feb. 2005 (production of LOTR games after Feb. 2005 have post in place).
|
|-
|Nr. 153
|2004, December 15
|Ripley's Believe It or Not!
|Ripley's Believe It or Not! Software Update
|
|-
|Nr. 152
|2004, August 27
|general
|FYI: STERN Pinball Flipper Evolution
|
|-
|Nr. 151
|2004, July 20
|Lord of the Rings
|Potential flipper & ring magnet fuse fatigue
|
|-
|Nr. 150
|2004, June 21
|general
|Back to Basics: Insertion/Replacement of EPROMS in SPI Games
|
|-
|Nr. 149
|2004, May 18
|Ripley's Believe It or Not!
|Potential Ball Trap by the Upper Left Pop Bumper (ask your Distributor for SPI Kit Nr. 502-5025-81)
|
|-
|Nr. 148
|2004, April 29
|The Lord of the Rings
|Balrog LED Module Installation, SPI Kit Nr.:502-5022-00
|
|-
|Nr. 147
|2004, January 19
|The Lord of the Rings
|Diverter Gate Adjustment Procedure
|
|-
|Nr. 146
|2003, December 18
|The Lord of the Rings
|FYI: The Lord of the Rings Tower Eject Learning Mode
|
|-
|Nr. 145
|2003, December 9
|Terminator 3 Rise of the Machines
|T3 Auto Launch Diode Harness Installation (SPI Part Number 502-5017-00)
|
|-
|Nr. 144
|2003, December 9
|The Lord of the Rings
|The Lord of the Rings Spanish Display & Speech Available
|
|-
|Nr. 143
|2003, October 22
|Terminator 3 Rise of the Machines
|T3 Software Update/Match Feature
|
|-
|Nr. 142
|2003, August 22
|Terminator 3 Rise of the Machines
|T3 Auto Launch Wire(s) or Coil Lug(s) Break Off
|
|-
|Nr. 141
|2003, August 13
|Terminator 3 Rise of the Machines
|Shooter Lane Switch Actuator Adjustment
|
|-
|Nr. 140
|2003, July 24
|Terminator 3 Rise of the Machines
|T3 Software Update v2.04 or Higher Eliminates POTENTIAL Reset Problem
|
|-
|Nr. 139
|2003, May 16
|Monopoly
|F21 (50vdc) Fuse Blows Intermittently, System Checks OK on
|
|-
|Nr. 138
|2003, March 21
|The Simpsons Pinball Party
|The display flashes a Tech-Alert upon Power-Up
|
|-
|Nr. 137
|2002, July 22
|Austin Powers
|CPU GAME ROM v3.01 Bug
|
|-
|Nr. 136a
|2002, June 21
|Playboy
|U7 Sound ROM Update DOES NOT RESOLVE the problem
|
|-
|Nr. 136
|2002, May 2
|Playboy
|U7 Sound ROM Change
|
|-
|Nr. 135
|2002, May 1
|Monopoly
|Optional Monopoly Butyrate Fix Kit (SPI: 502-5012-00)
|
|-
|Nr. 134
|2002, April 11
|general
|Difficulty in Playfield Glass Removal
|
|-
|Nr. 133
|2002, April 1
|Monopoly / Austin Powers
|CPU/Soundboard Modification Low Volume Setting Hum
|
|-
|Nr. 132
|2002, March 4
|Playboy
|Back To Basics: Using Your Adjustable Outlane Posts
|
|-
|Nr. 131
|2002, Jan. 23
|Monopoly
|Electric Company Sign / Backbox J2 Harness Re-dress
|
|-
|Nr. 130
|2001, Dec. 10
|Monopoly
|Tips & Tricks - The Water Works Rotating Flipper
|
|-
|Nr. 129
|2001, Oct. 22
|Monopoly
|Playfield Mylar, SPI Part Number: 820-5094-00
|
|-
|Nr. 128
|2001, Sep. 19
|Austin Powers
|Code Update v3.00 CPU/Display: Addition of Adj.60: Washington D.C. Enabled (Factory Defaults is "Off")
|
|-
|Nr. 127
|2001, Sep. 19
|Striker Xtreme / NFL
|Plastic Stadium Flashlamp Removal
|
|-
|Nr. 126
|2001, Sep. 19
|general
|The Bubble Level is Back!
|
|-
|Nr. 125
|2001, April 19
|general
|Quick Tip for Display Troubleshooting: U201 White Starboard System
|
|-
|Nr. 124
|2001, March 16
|Sharkey's Shootout/ High Roller Casino
|Software Update: Replay Bug Fix
|
|-
|Nr. 123
|2001, March 6
|High Roller Casino
|Ball Trap Fix @ Bottom Bumper
|
|-
|Nr. 122
|2001, Feb. 22
|High Roller Casino
|Roulette Wheel (Top and Bottom) Assembly
|
|-
|Nr. 121
|2001, Feb. 5
|Harley-Davidson
|Plastic (Butyrate) -15 Support Plate Kit(SPI Nr. 502-5003-67)
|
|-
|Nr. 120
|2000, Dec. 29
|Sharkey's Shootout
|Mystery Ball Magnet Fuse Fatique: CPU Software Code 2.04 Update
|
|-
|Nr. 119
|2000, Nov. 8
|general
|Pinball Preventative Maintenance Inspection
|
|-
|Nr. 118
|2000, August 21
|Striker Xtreme / Sharkey's Shootout
|Drop Target Replacement Procedure
|
|-
|Nr. 117
|2000, June 13
|general
|Please Join our Service Bulletin eMail Distribution
|
|-
|Nr. 116
|2000, June 12
|Titanic
|Titanic Redemption Game Potential Revenue Loss
|
|-
|Nr. 115
|2000, May 3
|Stiker Xtreme
|Stiker Xtreme Earnings
|
|-
|Nr. 114
|2000, Feb. 11
|Harley-Davidson
|Operator Alert #19 - Motor Relay
|
|-
|Nr. 113
|1999, Dec. 10
|Harley-Davidson
|HD Ball Guide... & Butyrate - 16... Kit
|
|-
|Nr. 112
|1999, June 7
|A13 >> Current
|CPU U218 & I/O U210 Pin-3 Removal
|
|-
|Nr. 111
|1999, Feb. 18
|South Park
|8MG E-PROM's for Expanded Speech & Sound Capabilities
|
|-
|Nr. 110
|1998, Nov. 24
|Space Jam >> Current
|Modular Stand-Up Targets: a new way to order
|
|-
|Nr. 109
|1998, Sep. 30
|Godzilla
|...Manual Addendum: Flipper Coils
|
|-
|Nr. 108
|1998, August 18
|Prior<<Batman Forever>> current
|"Sega"...& "Data East" ... Flipper Rebuild Kits
|
|-
|Nr. 107
|1998, August 13
|All Games (General)
|Fax Response Survey: How would you like your...
|
|-
|Nr. 106
|1998, June 2
|Multiple Games
|Large Dot Display Optional Enhancement Cable
|
|-
|Nr. 105
|1997, Nov. 21
|The X-Files
|...-Playfield Update Kit (500-6281-00)
|
|-
|Nr. 104
|1997, Sep. 25
|Multiple Games
|Future Parts & Service Pinball ...(Questionaire)
|
|-
|Nr. 103
|1997, July 14
|Playboy thru Rocky & Bullwinkle & Friends
|Solid State Flipper Bd. ( Non E.O.S.) conversion
|
|-
|Nr. 102
|1997, June 20
|The Starwars Trilogy-Special Edition
|FYI: What's New ("Y" Actuator Heavy Duty Sw.)
|
|-
|Nr. 101
|1997, June 10
|The Lost World: Jurassic Park
|Important Unpacking Information
|
|-
|Nr. 100
|1997, May 19
|The Starwars Trilogy-Special Edition
|Software CPU/Display Final Code Version
|
|-
|Nr. 99
|1997, May 13
|Multiple Games
|FYI: Correct P/F Glass Dimensions ...Wide Body
|
|-
|Nr. 98
|1997, April 8
|The Starwars Trilogy-Special Edition
|Addition of Reset Align. Bracket Kit
|
|-
|Nr. 97
|1997, April 8
|The Starwars Trilogy-Special Edition
|X-Wing Motor Bushing
|
|-
|Nr. 96A
|1997, May 12
|Space Jam >> Current
|Dot Matrix Display Bd. 4X Spacer/2X Bracket
|
|-
|Nr. 95A
|1997, April 11
|The Starwars Trilogy-Special Edition
|...Reed Sw. Replacement Kit...&Procedure
|
|-
|Nr. 94
|1997, March 3
|Lethal Weapon 3 >>Current
|Flipper Alignment Spots
|
|-
|Nr. 93
|1997, Jan. 27
|Space Jam
|FYI: ...problem in... I/O Power Driver Boards
|
|-
|Nr. 92
|1996, Dec. 5
|Apollo 13 >> Current
|FYI: MOSFETs in the White Star Bd. System
|
|-
|Nr. 91
|1996, Nov. 27
|Twister
|Magnet Processor Bd. & Disc Motor Updates
|
|-
|Nr. 90
|1996, Nov. 20
|Space Jam >> Current
|FYI: Sega Showcase Backbox
|
|-
|Nr. 89
|1996, Nov. 19
|Apollo 13 >> Current
|FYI: Switches
|
|-
|Nr. 88
|1996, Oct. 14
|All Games (General)
|Excerpt From Customer Fax
|
|-
|Nr. 86
|1996, Sep. 3
|Independence Day
|Potential Ball Trap in the Plastic Under-Trough
|
|-
|Nr. 85
|1996, May 15
|Twister >> Current
|New 2-Flipper Theory of Operation and Schematic
|
|-
|Nr. 84
|1996, March 5
|Golden Eye
|Fuse/Power Updates
|
|-
|Nr. 82
|1996, Jan. 23
|Apollo 13 >> Current
|The New "White P Star Board System"
|
|-
|Nr. 81
|1996, Jan. 9
|Apollo 13
|System Update
|
|-
|Nr. 80
|1995, Dec. 21
|Apollo 13
|Theory of Operation: P/F Mag. Intrface & 7-Seg.
|
|-
|Nr. 79
|1995, Dec. 18
|Apollo 13
|5 Amp to 3 Amp Slo-Blo Fuse Change
|
|-
|Nr. 77
|1995, August 24
|Current Games
|"What is this pinball machine trying to tell me?"
|
|-
|Nr. 75
|1995, August 22
|All Games
|CPU Board - Blanking Circuit Theory of Operation
|
|-
|Nr. 72
|1995, Feb. 17
|Mary Shelley's Frankenstein
|Creature: A Technical Overview
|
|-
|Nr. 70
|1995, Feb. 14
|Mary Shelley's Frankenstein
|Software Change Notice
|
|-
|Nr. 68
|1995, Jan. 27
|Frankenstein (+ games hereafter)
|New Service Feature: Bi-Directional Aud/Adj/Diag.

|}

==Technical Info==
===Schematics===
While these schematics were removed from Stern's web site quite some time ago, they can still be found using "the Wayback Machine". 

*BSMT2000 based WhiteStar MPU board - [https://www.pinwiki.com/wiki/images/e/ec/CPU_Sound_Bd.pdf Link] 
*Atmel based WhiteStar (modified) MPU board - [https://www.pinwiki.com/wiki/images/6/6b/CPUSNDIIPCB520-5300-00new.pdf Link] 
*I/O driver Board - [https://www.pinwiki.com/wiki/images/8/85/IO_Power_Driver_Bd.pdf Link] 
*6845 based display controller board - [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf Link] 
*Atmel based display controller board - [https://www.pinwiki.com/wiki/images/f/f8/Display_Controller_Bdnew.pdf Link] 
*High voltage display power supply board - [https://www.pinwiki.com/wiki/images/e/e3/Display_Power_Supply_Bd.pdf Link] 

===The White Star Board Set===
[[File:Stern WS Boardset.JPG|left|thumb|300px|Typical Early Stern White Star Boardset (Monopoly)]] 
The White Star System board set consists of three boards mounted to the the back box, but four boards total. The CPU / Sound board, I/O Power Driver board and the Display Power supply. Additionally, there is a dot matrix display controller mounted to the backside of the dot matrix display. On some games, the dot matrix display controller is mounted to the backbox instead. 

The first two White Star games, Apollo 13 and Goldeneye, both used an additional solid state flipper control board. Starting with Twister, the solid state flipper board was abandoned, and flipper control became an additional duty for the I/O power driver board. 

In addition to pinball machines, the White Star board set was used in several redemption games made by Sega and Stern. Some of the games are Wack-A-Doodle-Doo, Sega Sports, Titanic, and Monopoly redemption.
 
====CPU / Sound Board====
<center>
<gallery widths=500px heights=300px perrow=2 caption="Generations of the Sega/Stern White Star MPU">
File:A13MPU.jpg|<center>Sega White Star CPU/Sound Board 520-5136-00 Rev. D with 3 channel audio output (Apollo 13)</center>
File:Sega WS CPU Sound 520-5136-16 Rev. D.JPG|<center>Sega White Star CPU/Sound Board 520-5136-16 Rev. D (Wack-A-Doodle-Doo)</center>
File:Stern WS CPU sound.JPG|<center>Stern White Star CPU/Sound Board 520-5136-16 Rev. E (Monopoly)</center>
File:SternWhiteStarAtmelProcessor.jpg|<center>Stern White Star CPU/Sound Board II 520-5300-00 (LOTR and forward). U201, U213, and U413 are socketed on this board as a result of alkaline damage abatement.</center>
</gallery>
</center>
 

There are two versions of the White Star CPU/Sound board.

The board used in Sega machines starting with Apollo 13 (A13) and Stern machines up to Terminator 3 (T3) are the standard version as shown above with the BSMT2000. There were different revisions of this board, which included slight component changes and modifications. However, there were some distinct changes to the board from revision D to revision E. The Q9 transistor located just below U212 (RAM memory) was removed, and a two pin jumper (JP1) was added. Additional circuitry allowed for increased RAM memory from 8K to 32K. Jumper JP1 is used to select between use of a 6264 or a 62256 RAM. '''Note:''' While a 62256 RAM can be used in any game MPU, Sharkey's Shootout specifically requires a 62256 RAM. 

Stern machines starting from Lord of the Rings (LOTR) used a different version of the White Star CPU/Sound board called White Star CPU/Sound Board II or more commonly WhiteStar (modified), part #520-5300-00. Stern had this in-between version made because the BSMT2000 audio chip wasn't available anymore and having it reproduced was too expensive. The White Star II therefore uses an BSMT2000 emulation circuit consisting of an Atmel AT91R40008 microcontroller and an Atmel AT49BV1614-11TC 16Mbit flash memory. Later boards use a AT49BV162AT-70TI flash memory chip. Both flash chips are obsolete now. The boards are known for sudden sound failures sometimes because of a bad flash chip and it is advisable to buy a spare. If the amplifier section is good the most common cause for sound failures is the U414 Xilinx CPLD. This chip is a programmed by Stern via the JTAG connector. While some repairmen have the skill to replace the chip, only Stern can "flash" the code into the chip.

Note: Stern states that the Atmel version board is backwards compatible with the standard (BSMT2000) version, so it can be used in *some* White Star based games (in most cases, Stern branded White Star games only - including South Park and Harley Davidson) prior to LOTR as well. However, the only games which the board can be installed in must use 8mb EPROMs for the sound section versus the 4mb EPROMs more commonly found on Sega White Star based games. If the CPU/Sound board II is used in early games, Starship Troopers for instance, some sounds may not render correctly. 

Additionally...The original BMST2000 based board is not forward compatible with later games like LOTR, etc. 

The BSMT2000 based White Star sound system is nearly identical to the sound circuitry found on Data East/Sega soundboards 5020-5050-0x, 5020-5077-00 and 5020-5126-02.

The board uses TIBPAL16L8 PAL ICs. These are programmable logic chips Stern used to condense a great deal of TTL logic into a single chip. Each PAL is marked with a colored dot for identification and configuration management. U213 is one of these PALs that is within the battery corrosion area. It is readily available, already programmed under part number 965-6504-00 (blue dot), the only exceptions to the blue dot being Sharkey's Shootout which uses part number 965-5023-00 (gold dot) and Lord of the Rings LE with a shaker motor installed which uses a different part number (the standard LOTR without a shaker motor uses the standard 965-6504-00 but the software version supporting the shaker motor will only run on the alternative U213).

There are two more PAL chips on the board at U19 (yellow dot, 965-0136-00) and U20 (white dot, 965-0137-00). These aren't needed very often for repair of the sound section but they do fail now and then.
 
Sega first used standard TIBPAL chips and later switched to reprogrammable PALCE devices. The latest boards from Stern use GAL chips. In the old PAL chips, fuses are burned so they do not have a data retention period. For the programmable logic chips the data retention period is generally specified at 20 years or more at operating temperature. The first White Star boards are from 1995 Beginning in 2015, all with reprogrammable chips begin to exceed the data retention period and although big problems are not to be expected, it wouldn't be surprising if these parts begin to fail.

The programmable logic in the board design makes it harder to repair the boards because of the grey area it causes in the schematics as there aren't any logic diagrams of these available. In short; you don't know what they do so you don't know what the output should be.

'''"Blink Codes"''' do not exist for the 68B09E or the Atmel based MPU. With one exception (Atmel based board) anything blinking is a side-effect of improper board operation. The blinking may help you diagnose the actual board problem, but blinking LEDs are not driven with intent by the processors. i.e. There are no "Bally -17-like Blink Codes".

The single exception to this is LED1 on the Atmel based MPU. LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin # 157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another).

There are two [http://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] (Joint Test Action Group) connectors available on the Atmel based board. One connects to the Xilinx [http://en.wikipedia.org/wiki/Complex_programmable_logic_device CPLD] (Complex Programmable Logic Device). The other connects to the Atmel R40008 processor. The JTAG interfaces to this board and their use have not been documented publicly.

As of April 2014, schematics for the 520-5136-16 board are no longer available from Stern's website. 
As of April 2014, schematics for the 520-5300-00 board are no longer available from Stern's website. 

=====BSMT2000 DSP Info=====
[[File:BSMT2000.jpg||left||thumb||300px||BSMT2000 audio chip]] 
Like the earlier Data East boards, the first White Star generation uses a TI DSP for sound processing. The chip is just a relabeled mask programmed stock Texas Instruments TMS320C15NL-25 DSP. The 8K mask programmed ROM is custom programmed during manufacturing and can not be read out, reprogrammed, or altered in any way. Only the ones labeled BSMT2000 will work in a pinball. For prototyping, the TMS320P15NL-25 and TMS320E15NL-25 were available which included a more-or-less standard 27C64 EPROM. The pictures on the left shows a BSMT2000 and a TMS320P15NL-25 out of a Sega board. The hand labeled chips are rare but if you have one in your pin, you can read it out. The security fuse was not set on the device in the picture. If you build an adapter using a 27C64 and some logic which puts the DSP in microprocessor mode and does the address decoding it might even be possible to use the C10 and C15 devices because the internal ROM is not used in this mode.
 

=====WhiteStar Switch Circuitry=====
Both versions of rhe WhiteStar CPU/Sound board employ an 8 by 8 (8 switch columns, 8 switch rows) switch matrix. In addition to the typical switch matrix, an extra column of switches, which are dedicated to specific functions like coin door switches, appear on all WhiteStar games.

Flipper cabinet and end of stroke (EOS) switches are part of the dedicated switch set on games after Goldeneye.

A combination of microswitches, opto switches, leaf switches (on most drop target assemblies), and reed switches are used.
 

====Power Driver Board====
The Power Driver board supplies fused power, GI power and fusing, lamp matrix circuitry as well as coil and flash lamp drivers. A watchdog circuit also must communicate with the MPU periodically to allow the MPU to boot and operate properly. 

As of April 2014, schematics for the 520-5137-01 board are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-64 board (Sharkey's Shootout Tournament Edition only) are no longer available from Stern's website. 

As of April 2014, schematics for the 520-5137-01 board (100 ohm resistors added on J2 aux. port lines) are no longer available from Stern's website. 

High current coils (50vdc) 1-8 (group 1) and 9-16 (group 2). Q15 and Q16 typically drive the left and right flippers respectively. 
Low current coils (20vdc) 17-24 (group 1) and 25-32 (group 2). 
 

Please be advised that four revisions of these board exist. The letter after the number indicates the revision. See below. All existing Stern schematics are wrong.

=====Revision D: First revision=====

=====Revision E: Second revision=====
[[File:Stern WS Driver.JPG|left|thumb|300px|Stern White Star I/O Power Driver Board Rev E]] 

*Not fully stuffed. Parts for flipper boards connector J4 and J5 are not stuffed.
 

=====Revision F: Third revision=====
[[File:IO driver rev F.jpg|left|thumb|300px|Rev F of the Sega/Stern IO Power Driver Board.]] 

*C25 changed from 470µF 100V to a 330µF 160V Snap-In capacitor
*U210 pin 3 is cut to allow for a 10% input voltage tolerance before resetting, aka "low line voltage". This was documented in Stern service bulletin #112 which can be found [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf here]. However, a better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 5% (to about 4.75VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

*J2 modified and 100 Ohm resistors R258 to R260, R273 -R277 added (see schematics)

 

=====Revision G: Fourth revision (not documented by Stern)=====
[[File:IO driver rev G.jpg|right|thumb|300px|Rev G of the Sega/Stern IO Power Driver Board.]] 
The most obvious change to the Rev G driver board is the addition of eight 100 ohm resistors under the J2 aux out connector (R258-260, R273-277). This board is backwards compatible with all machines that use the I/O Power Driver board. It is possible to add these resistors to the back of J2 for I/O board Rev F, jumping from the connector pins to the capacitors below the J2 connector to make the board compatible with those games that use the J2 connector.

This is the only version that will work with the TOPS system.

Parts deleted:

*Original R256, D228, R255 and C236 above U210 were removed

Modification 1:

J3 Pin 8 is no longer a key pin. The installed pin is connected to R255/R256 and to C236. The other side of these parts is connected to:

*R255 to D217 banded side like R245 to R251
*C236 to GND like C229 to C235
*R256 to U203 Pin 11 (LST lamp status)

The LST trace to D221 to D227 is missing. The diodes are still connected to the status output line of the VN02 solid state relays. It seems that this status is not queried by the game software or can just be ignored.

Modification 2:

*U210 Pin 3 is connected to R257.
*R257 is connected to GND but not stuffed!

Modification 2 is not necessary. A better modification for U210 is to tie pin 3 to 5VDC, which sets the voltage watchdog to trip when voltage drops 10% (to about 4.50VDC). This is discussed in the PinWiki, [https://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#DS1232_Voltage_Watchdog here].

New parts:
*R255 1K
*R256 39K
*R257 not stuffed
*C235 470pfd

===== Sharkey's Shootout Specific Driver Board =====
[[File:SharkeysShootoutWhiteStarMod.jpg|left|thumb|300px|Cuts and jumpers applied to the Sharkey's Shootout specific I/O Driver Board.]] 
The now defunct Stern web site containing schematics listed a few differences in the I/O Driver Board for Sharkey's Shootout. Those differences are identified in the image at left.

One other change to the board is shown on page 5 of the Sharkey's Shootout unique I/O Driver Board. Fuse F20 is changed from a 3ASB to a 4ASB.
 

===== RottenDog WhiteStar 5V Voltage Regulator =====
[[File:RottenDogWhiteStarVoltageRegulator.jpg|left|thumb|300px|RottenDog LM317 Replacement.]] 
The RottenDog aftermarket power/driver board uses the voltage regulator shown at left, primarily because the older LM317 voltage regulator has gone obsolete.
 

===== Lamp Matrix =====
The WhiteStar system is somewhat similar to previous lamp matrices designed by Data East, Sega and Williams. The main difference is instead of 8 lamp columns and 8 lamp rows (the typical 8 by 8 matrix), two additional lamp rows are used enlarging the matrix to 8 by 10.

===== TOPS Tournament System Driver Board Compatibility =====

Only the latest revision G is compatible with the Stern tournament system (TOPS). With earlier revisions while everything including the tournament sign seem to work ok a tournament can not be started. Pressing the tournament button will result in a 'Tournament Game Paused' message displayed on the DMD. The tournament button itself will also not light up during normal operation. The J3 Aux In connector has an additional pin instead of the key pin on these boards. Because of this the LST line to the lamp drivers goes nowhere on this revision.
 

====Display Controller Board====
[[File:Sega 520-5055-01 DMD Control Board.JPG|thumb|left|300px|Sega White Star Display Controller Board]]
[[File:AnnotatedDMDController.png|thumb|right|300px|Sega White Star Display Controller Board Layout with Ground Connections Shown]] 
The Schematics for this board can be found [https://www.pinwiki.com/wiki/images/b/b9/Display_Controller_Bd.pdf here]. 

The display controller board doesn't contain circuitry to provide the on board 68B09E with a "reset" pulse. The reset signal is provided from the games MPU via a pin at the ribbon cable connection (J1 pin 20). The surface mount version of the board has provisions to provide a reset signal at U10, but the necessary components are not stuffed.
 

[[File:Stern WS DMD Controller.JPG|thumb|left|300px|Stern White Star Display Controller Board, surface mount version.]] 
As of April 2014, schematics for the 237-0255-00 DMD controller board (primarily surface mount components) are no longer available from Stern's website. 
 

[[File:SurfaceMountFailedSolderJoints.jpg|thumb|left|300px|A fractured solder joint (circled) on this board prevented the "power on" LED from ever lighting.]] 
The surface mount version of this board sometimes has dubious solder connections at some of the surface mount resistors and capacitors. The picture at left shows a fractured solder joint on the resistor in series with the "power on" LED. The LED would never light. Another fractured solder joint on the same board prevented the reset pulse from the MPU board from ever reaching the on board 68B09E.
 

====Display Power Supply====
[[File:Stern WS DMD PSU.JPG|left|thumb|300px|Stern 520-5138-00 Display Power Supply]] 

This WhiteStar game system high voltage power supply (for displays) is an evolution from the larger Data East power supply. The high voltage section of this board is nearly identical to the high voltage section of Data East power supplies 520-5047-01 and 520-5047-02. Of course, those earlier Data East power supply boards regulate and supply more than display high voltages (i.e. 5VDC). As such, the WhiteStar board could be made more compact while using almost identical parts.
 

====128 x 32 Dot Matrix Display====
All Sega and Stern White Star games make use of a 128 x 32 "standard" dot matrix display.
 

====White Star Manufacturing Quality====
[[File:WhiteStarFactoryUpdate.jpg|300px|left|thumb|Factory updates to the Sega/Stern White Star MPU.]]
[[File:WhiteStarMPUSolderSideFactoryMod.jpg|300px|right|thumb|Ceramic cap, 10 ohm 1/4 watt resistor, and a trace cut.]] 

Generally, White Star boards are manufactured quite well. The traces are very fine, making alkaline damage repair difficult. But, those batteries shouldn't be on the board, should they? The Atmel based MPU board uses a multi-layer PCB, which increases the need for clean component removal and replacement.

Pictured at left, are two factory updates to the original Sega/Stern White Star MPU (BMST2000 version). These are normal, and not "hacks".

As can be seen in the picture at right, a ceramic 100pF cap and a 10 ohm 1/4 watt resistor have been added and a trace has been severed. This modification results in the 10 ohm resistor and the cap being placed between BMST2000 "CLKOUT" signal at pin 6 and ground at pin 10.

An additional 100pF cap is placed between pin 5 "E" and 6 "!E" of U1.
 

[[File:WhiteStarU203CutAndDiode.jpg|300px|left|thumb|Another factory update to the Sega/Stern White Star MPU.]] 
Another factory update to the left of U206 involves two cuts, and the addition of a diode between D3 and R430. Again, this is not a "hack".
 

[[File:WhiteStarPCBSolderMask.jpg|300px|left|thumb|Small traces lead to some components on White Star boards, enabling better manufacturing quality.]] 
By the time White Star boards were being manufactured, improved methods of controlling solder temperature and junction temperature at the through-holes was much better understood. In the picture at left, the "spider" connections at some through-holes, allow less heat to be used to create quality solder joints.
 

===The Wire Coloring Code===
White Star games do not use color coding system. Instead, the wire color was marked accordingly in the associated documentation, (ie. a green wire with a brown trace is referred to as GRN-BRN, orange with violet is ORG-VIO, white is just WHT, etc.).
 

===Trough Opto Boards===
++++ Need pics of the single opto transmitter and receiver boards ++++++ 
[[File:Stern WS Trough Opto Transmitter.JPG|left|thumb|300px|Stern White Star Trough Opto Transmitter (Later Games)]]
[[File:Stern WS Trough Opto Receiver.JPG|left|thumb|300px|Stern White Star Trough Opto Receiver (Later Games)]] 
All White Star Games use trough opto boards at the location of the trough VUK which feeds the ball to the shooter lane. Earlier White Star games (Apollo 13 to Viper Night Drivin') use only a single opto above the VUK plunger. Later White Star games (Lost in Space to NASCAR / Grand Prix) use a two opto system. The lower opto serves a dual purpose. It is the opto just above the VUK plunger like earlier games, but is also designated as trough switch #4. The upper opto is designated as the "stacking opto". Its purpose is to identify when a ball inadvertently gets "stacked" above a ball located at the VUK plunger. 

To briefly summarize the operation of White Star VUK opto boards, if an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch. The components used on the opto receiver board are designed to do as such. 

The transmitter side is simply an ultra-red LED with a current limiting resistor. The receiving opto is the same style ultra-red LED, and is able to detect the light wavelength emitted from the transmitting LED. By using discrete components on the receiving side, the appropriate signal is sent to the CPU via the switch matrix return (row). When LEDs are paired together in this type of fashion, the receiving LED emits a very small amount of voltage, when the proper light wavelength is present. By employing such a design, failure on the receiver opto side is more common. 

This particular system is contrary to how Bally / Williams WPC CPUs handle opto pairs. Equally, WPC games employ infrared (IR) opto switch pairs. If interested in learning the theory of operations for the White Star opto trough upkicker boards, please consult the manual. Sega / Stern have included some excellent, detailed, technical documentation within their manuals. 

As of April 2014, schematics and troubleshooting info for the trough upkicker dual opto boards are no longer available from Stern's website.

Once significant source of trouble with these trough boards is fractured header solder joints. 

===Magnet Processor Board===
[[File:Sega mag driver board.jpg|300px|thumb|left|Sega 520-5143-00 Magnet Processor Board]] 
Only two Sega games used this style of magnet processor board - Twister and Goldeneye. When U1 for Twister is installed in the board, the board's part number is 520-5143-01. The part number for the board when U1 is written for Goldeneye is 520-5143-02. Difference between the board used on each game is the different custom PIC / GAL chip used at position U1 and the Goldeneye board has R10, R11, R12, R13, D11 and D12 stuffed. This is not always the case with boards for Twister.
 

===Flippers===
[[File:Stern Flipper Assy.JPG|left|thumb|300px|Typical White Star Left Flipper Assembly (Monopoly)]] 
All Sega / Stern White Star flipper assemblies are solid state controlled. Apollo 13 and Goldeneye are the only two White Star games which use a separate solid state flipper control board located in the game's lower cabinet. Starting with Twister, the flipper board was abandoned, and circuitry for the flippers was solely controlled by the FETs on the power driver board. 

Please note that the adjacent pic of the White Star flipper assembly has a Williams flipper link / plunger installed.

The drive circuit for White Star games is different than traditional flippers. The flipper coil is single-wound. There is no "hold" winding, just a single "kick" winding. Because the flipper will get hot if the kick winding runs continuously, after the initial upstroke, the computer continuously cycles the coil on so that it stays up. According to the manual, the flipper is pulsed about 1/12 of the time.

The flipper coil must have a snubbing diode.

A normally closed EOS switch is present. The purpose of the EOS switch is to detect when a fast-moving ball has forced the flipper down ("foldback"). Unlike a traditional or Fliptronic mechanism, the EOS switch is not used to detect end of stroke. That is, the EOS switch closing does not cause a switch from "kick" to "hold". If the flipper is supposed to be up, and the EOS switch opens, the game will re-energize the flipper coil. This helps with some features, particularly "laser" kickers that fire the ball into the flippers. The EOS switch should be present for improved play, but if it's broken, the flipper will work for the most part. However, in some instances, a flipper with a broken or missing EOS switch may be noticeably weaker. If a flipper seems weak or lethargic, the flipper mechanisms have been rebuilt, and the EOS switch is broken, try replacement of the EOS switch first before considering other options.
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
Solid state pinball machines typically have a built in system for audits and adjustments. All White Star based machines use a system called "Portals". The Portals interface is a carry over from the last two Sega games (Baywatch and Batman Forever) which used the original Data East board set.

====Portals (Coin Door Test Buttons)====
[[File:Stern white star coin door inside.JPG|300px|thumb|left|The Portals control panel used on most White Star games (Monopoly)]] 
The Portals system has a very user friendly, simple navigation system. Unlike previous Data East / Sega games, having to scroll through all of the audits and adjustments is a thing of the past. Diagnostic testing (including game specific assembly tests), audits, and adjustments can all be quickly accessed via the initial display menu graphical interface. The 3-button control panel (in most cases, except some earlier White Star games) used to access Portals is located on the coin door.
 

<center>

<gallery widths=300px heights=120px perrow=3 caption="DMD Screens during Various Tests in Portals ">
File:Stern WS test switch.JPG|<center>Switch test (similar to switch edge test in Williams speak)</center>
File:Stern WS test active switch.JPG|<center>Active switch test (similar to switch level test in Williams speak)</center>
File:Stern WS test ded switch.JPG|<center>Dedicated switch test</center>
File:Stern WS test lamp options.JPG|<center>Very flexible lamp test options</center>
File:Stern WS test single coil.JPG|<center>Coil test</center>
File:Stern WS test trough full.JPG|<center>Trough clear, but equally a good test for the trough and shooter lane switches</center>
File:Stern WS test trough 3 in trough 1 shooter.JPG|<center>Advancing through trough clear</center>
</gallery>
</center>

=====Setting Free Play=====
 

===Coin Door Switches===
[[File:Stern coin door buttons.JPG|300px|left|thumb|Coin door Switches Located Inside a White Star Game (Monopoly)]] 
Most White Star games have two switches located on a bracket inside the coin door (hinge side). The upper switch is the memory protect switch. This switch is used so that nothing can be written to the memory, unless the coin door is open. The memory protect switch is not part of the switch matrix, nor is it one of the dedicated switches. Although it does connect to the CPU / Sound board via the same connector as the dedicated switches, its state is processed by a different chip (U213) versus the dedicated switches (U206). 

The lower switch is an interlock style "kill" switch. This kill switch is used to kill all power to the solenoids, when the coin door is opened. Since it is an interlock style switch, it can either be depressed (when the coin door is closed), or it can be extended outward to turn the switch on. To extend the switch to the on position when the coin door is open, grasp the switch, and gently pull it out to the lock position. 

The kill switch is a double pole switch. Wiring to one pole of the kill switch is BLK-YEL and BLK-YEL, while the other is RED-WHT to WHT-RED (yes, the colors do not match!)
 

== Problems and Solutions ==

=== Power Problems ===
===Fuse Table===
[[File:WhiteStarFuseTable.jpg|400px|left|thumb|The typical fuse table. This table appeared in the Stern Sopranos manual.]] 

=== MPU boot issues ===

Damage resulting from alkaline corrosion is the most prominent reason for the MPU to fail to boot.

If the GI lamps are blinking at about a 1Hz rate, this means that the MPU is not booting and that the I/O Driver board is sending a reset pulse to the 68B09E on the CPU/Sound board.

The following can be examined:

*Alkaline corrosion
*Inter-board ribbon cable fault inhibiting the reset of the CPU/Sound board watchdog timer DS1232. The timer is reset via signal DRV0, a lamp matrix signal.
*Failed ROM. Note that the ICs on WhiteStar CPU/Sound boards are ALL installed notch down. Installing a ROM upsidedown and powering on immediately destroys the ROM.

==== Relocating the Battery from the MPU board ====
[[File:WhiteStarAlkalineDamage.jpg|300px|thumb|left|The aftermath of batteries which leaked. This board is beyond repair, and good only for salvage parts.]]
Relocating the 3xAA batteries off the MPU board or installing other alternatives for memory retention is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards. 

One option is to install a remote battery holder, and place the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) components of the MPU board. Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually. 

Another option is to install a memory capacitor. This method is considered to be better than a remote battery holder, because memory capacitors are not prone to leakage like alkaline batteries. The only drawback is that the memory capacitor has to be properly recharged to be effective. If a game has the potential of sitting dormate without being turned on for extended periods (typically months), the memory capacitor may not hold the memory. 

A third option is to install a lithium battery with a battery holder. Lithium batteries are much less likely to leak than alkaline batteries, and they do not need to be recharged.

Whatever you do, GET THE BATTERIES OFF THE BOARD! It's not a matter of if they will leak, it's a matter of when. WhiteStar boards are pricey to replace, and repair is difficult/expensive/even impossible due to the very fine traces used on the board. 

[[File:WhiteStarRemoteBatteryHolderAnnotated.jpg|300px|thumb|left|A White Star MPU Board with Remote Battery Pack Connected. The Positive (+) terminal is circled. D200 and D201 are highlighted inside the rectangle. Note that the battery installation date is recorded with a Sharpie. Also note the long wires, allowing the holder to hang well below the backbox boards, another precaution for leaky batteries.]] 
Adding a connector between the battery pack and the MPU board is a good idea. In doing this, the battery pack can easily be removed from the MPU board. Plus, if the batteries are forgotten, and do leak, the MPU board may not have to be removed to add another battery pack. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is available, a jumper can be soldered in the first battery position. Likewise, a diode can be placed in this position instead. Using a diode instead of a jumper will prevent the batteries from being charged and 'cooked' by the game if blocking diode D201 on the MPU board fails. Keep in mind that a second (redundant) diode added to the circuit will reduce the backup voltage to the RAM memory by .5 to .7 volts. Install a 1n4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the (+) terminal marking on the MPU board, and away from the battery pack. 

On the MPU, solder the battery cables: positive (red wire) to the "+" pad and ground (black wire) to the "-" pad.

Since the MPU board is already out, another good practice is to check the D201 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board's +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. Alkaline batteries do not like being charged. They will heat up, and fail rather quickly. In worse cases, the new batteries can even leak or explode if charged. Testing the D201 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D201 diode with a 1N5817 (a 1N4004 will work in a pinch), or add a redundant 1N4004 to the battery pack. Once again, if a second (redundant) diode is added to the circuit, it will reduce the backup voltage to the RAM memory by .5 to .7 volts 

Testing the D200 diode is a good idea too. The D200 (1N5817) diode is used to keep the backup batteries from powering the complete MPU board when the power is off. A symptom of a failed D200 diode are batteries which deplete rapidly.
 

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack's voltage at the '''VBATT''' test point on MPU board. All battery packs are pretty cheaply made, and failures "out of the box" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:White Star Mem Cap.JPG|300px|thumb|left|Installation of a Memory Capacitor]]
A memory capacitor is a great choice for memory retention, provided that the game will be turned on more frequently than not. If the game will not be turned on for several months, the memory cap may not stay charged. In turn, the memory may not be retained. 

It is recommended to use a 1F (Farad) 5.5v memory capacitor. The lead centers on a common, button memory cap are shorter than the "+" and "-" through holes where the factory battery holder was installed. To overcome this, solder a short wire onto the negative lead of the cap. Then, bend the lead at a 90 degree angle, so it is now parallel to the bottom of the memory cap. Place the positive lead of the memory cap into the "+" of the board, and then place the wire from the negative lead into the "-" of the board. Solder both leads in place. 

Please note that when using a memory cap, the D201 diode must be removed (or jumped), and a 0 ohm jumper or a 100 ohm resistor (or similar value) should be installed. This purpose of removing the D201 diode is so the memory cap can be properly charged when the game is on.
 

==== Repairing Alkaline Corrosion ====
[[File:WhiteStarInsidiuosCorrosion.jpg|300px|right|thumb|Corrosion can hide in many hard to find places.]]
Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the batteries are mounted on the top of the board with plenty of board beneath it for the corrosion to leach onto. Components well below the battery holder are often damaged.

Remember, battery corrosion is alkaline. Harkening back to the dim and distant past, remember your Chemistry 101. Alkaline is neutralized with acid. Most commonly used is vinegar, since it is an acid. Diluting the vinegar to half strength by adding an equal amount of water (50/50) is a good idea to prevent adverse impact to adjacent areas of the board.

[[File:WhitStarAlkalineCorrosion-1.jpg|300px|left|thumb|This MPU sustained alkaline damage. Sockets for the 68B09E processor and the 6264 RAM have been removed.]]
[[File:WhitStarAlkalineCorrosion-2.jpg|300px|right|thumb|More components removed, the alkaline damaged traces sanded, and the damaged area treated with 50/50 vinegar and water.]] 
Argh! The MPU pictured at left has sustained alkaline damage. In this case, the damage was repairable. Most of the time, alkaline damage to White Star MPUs is more substantial and beyond economical repair.
 

[[File:WhitStarAlkalineCorrosion-3.jpg|300px|left|thumb|Bare copper traces tinned.]]
[[File:WhitStarAlkalineCorrosion-4.jpg|300px|right|thumb|All components (or sockets) reinstalled, and nearly ready for test.]] 
The completed board shown on the right took a few hours to cleanup, repair, verify, and game test.
 

[[File:StarShipTroopersMPU.jpg ‎|1100px|center|thumb|A StarShip Troopers MPU, with widespread alkaline corrosion abated professionally.]]
[[File:WhiteStarComponentLayout.jpg|1100px|center|thumb|Components in WhiteStar Corrosion Area. Click to enlarge. Note: "104" refers to .1uf ceramic cap, 470 refers to 470pf cap.]]

===== Continuity Chart of Pin Outs in Battery Damaged Area =====
Just below the battery holder, the CPU EPROM and RAM both reside. Both of these chips and their sockets are susceptible to battery damage. Provided that the alkali damage breached the chip sockets, it is always best to check continuity on the new work performed. Below is a chart of the pin outs between the RAM (U212), EPROM (U210), and CPU (U209) chip. This chart will hopefully come in handy should repair of this area is necessary.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Signal
!68B09E Pin (U209)
!ROM Pin (U210)
!RAM Pin (U212)
!PAL Pin (U213)
!Other
|-
| Vcc ||7||32||28||20||
|-
| GND ||1 & 39||16||14||10||
|-
| A0 ||8||12||10||||
|-
| A1 ||9||11||9||||
|-
| A2 ||10||10||8||||
|-
| A3 ||11||9||7||||
|-
| A4 ||12||8||6||||
|-
| A5 ||13||7||5||||
|-
| A6 ||14||6||4||||
|-
| A7 ||15||5||3||||
|-
| A8 ||16||27||25||||
|-
| A9 ||17||26||24||16||
|-
| A10 ||18||23||21||15||
|-
| A11 ||19||25||23||8||
|-
| A12 ||20||4||2||9||
|-
| A13 ||21||28||26||3||
|-
| A14 ||22||29||---||2||U211-2 (XA0)
|-
| A15 ||23||3||---||1||U211-5 (XA1)
|-
| A16 ||31||13||11||||U211-6(XA2)
|-
| A17 ||31||13||11||||U211-9 (XA3)
|-
| A18 ||31||13||11||||U211-12 (XA4) - Prior to rev. E boards
|-
| D0 ||31||13||11||||
|-
| D1 ||30||14||12||||
|-
| D2 ||29||15||13||||
|-
| D3 ||28||17||15||||
|-
| D4 ||27||18||16||||
|-
| D5 ||26||19||17||||
|-
| D6 ||25||20||18||||
|-
| D7 ||24||21||19||||
|-
| /ROMCS ||---||22 (BSMT2000) 24 (Atmel)||---||19||
|-
| /RAMCS ||---||---||20||18||
|-
| /E ||---||24 (BSMT2000) 22 (Atmel)||22||4||U1-6
|-
| /CS ||---||---||26||||Q9-1 - rev. D or JP1 (8K) - rev. E
|-
| R/W ||32||---||27||7||
|}

 

==== Connecting a logic probe to the MPU ====
[[File:WhiteStarConnectingALogicProbe.jpg‎|300px|thumb|left|Connecting a logic probe to a Sega/Stern White Star MPU]]
[[File:WhiteStarModifiedConnectingALogicProbe.jpg‎|300px|thumb|right|Connecting a logic probe to a Stern White Star (Modified) MPU]] 
Connecting a logic probe to a Sega/Stern White Star board set (left) is simple. 
Both 5V and Ground test points are made available on the MPU board.

Connecting a logic probe to a Stern White Star (modified) board set (right) is simple too, but a 5V connection point isn't provided. 
Connect the positive lead of your logic probe to either side of the inductor labeled FB1.
 

==== Using a PC Power Supply For Bench Testing ====

===Low 5VDC and Game Resets===
Some symptoms of a game which repeatedly resets upon boot up are:

#General illumination lamps will repeatedly flash on and off (the GI relay can be heard clicking on / off).
#The DMD will display the initial boot screen, show the display ROM revision number, go blank, and then repeat this process.
#The sound board (depending on the age of the game) may only emit a "blip" sound or a shorter than usual initial sound clip.

In some of the above instances, the DMD display may or may not light up at all. 

The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer. 

U413, which is located on the CPU / sound board next to the reset button, is a [https://datasheets.maximintegrated.com/en/ds/DS1232.pdf Dallas Maxim DS1232] monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC. 

If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. Another location to measure the +5VDC is right on the metal casing of the LM338K regulator (U19), If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338K regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto transmitter board may be at fault. 

Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. The +5V test point on the CPU / sound board is located just to the left of the 6809EP CPU chip (U209) on the board. If the voltage drastically differs between the measurement of the I/O Power Driver Board and the CPU / sound board, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board. 

==== DS1232 Voltage Watchdog ====
[[File:WhitestarDS1232Pin3Clipped.jpg|left|thumb|300px|While this looks to be an error, it's actually a factory modification to the DS1232 reset generator. While this part is on the CPU/Sound board, there is an identical part on the driver board, which will have pin 3 clipped also. On the CPU pin 2 (Time Delay Set) might also be clipped. Pin 2 and 3 are left unconnected from the factory on the WhiteStar (modified) CPU/Sound board.]]
Both the WhiteStar MPU and Driver boards employ a DS1232 voltage watchdog. From the Sega and Stern factory, pin 3 is almost always clipped. Pin 3 is used to select the voltage tolerance the chip is to enforce.

A discussion regarding the proper connection of pin 3 was offered by John Robertson on rec.games.pinball, and is copied below.

Begin discussion...

You read it here (rec.games.pinball) first!

Looking into a problem with our Roller Coaster Tycoon where the game
would cut out the lights and coils for up to a second at random
intervals. This would happen perhaps once or twice every day or two.

Digging into the game I noticed that the Dallas supervisor chip used in
both the original Stern and the Rottendog replacement Driver Board both
left pin 3 (LOP) floating. Now this pin is there to select the Vcc
tolerance - if grounded it is 5% and if tied to Vcc it is 10%. However
the schematics now show pin 3 as floating.

Sega Service Bulletin SB112 (June 7, 1999) had recommended cutting pin 3
(to floating) on both Dallas DS1232s (MPU & Driver PCBs) where the
factory (at that time) had connected pin 3 to Gnd (5%). Sega, then Stern
continued this practice of either cutting or leaving pin 3 floating.
Rottendog also did this on their replacement board.

http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf

I was curious what would happen and if this idea of cutting the leg or
leaving it floating was recommended by Dallas. So I pulled up both the
original Dallas documents and the Maxim Application Note and in neither
case did they suggest that pin 3 should be floating - no connection.They
said it was to be connected to either Gnd or Vcc.

https://datasheets.maximintegrated.com/en/ds/MAX1232.pdf

https://pdfserv.maximintegrated.com/en/an/AN581.pdf

I then asked Maxim (who now make Dallas Semi chips) to comment on what
happens when pin 3 is floating - they replied today (Nov 25, 2019):

Thank you for contacting us.

It is not recommended to leave the TOL pin open since it is a digital
input and noise can make it oscillate, there is no internal pulling
resistor, so please do indeed connect it to GND or Vcc.

Regards,
Javier Monsalve
Maxim Applications

We had already tied pin 3 to Vcc (+5) as of Nov 23, 2019 to check my
assumption that floating was wrong, and the intermittent cutting out
problems had indeed disappeared!

The game has been running for days now with no hiccups and we shall be
leaving it running at least one more day before sending it to its new
home. We are monitoring the Vcc with a Mooshimeter logging 5V, to see if
Vcc drops below any reasonable threshold and a Heathkit logic probe
monitoring the R (pin 5) of the DS1232 as the Heathkit logic probe
stores momentary state changes (turns on a 'memory' LED).

Therefore, based on our tests, and the advice from Maxim, the
manufacturer of the DS1232 IC Supervisor chip, we can now say that you
need to tie pin 3 of the DS1232 to Vcc! Do NOT leave it floating as per
Sega Service Bulletin SB112!

Hope this helps!

John :-#)#
 

[[File:RottenDogDS1232SolderBridge.jpg|left|thumb|300px|An (probably) intentionally created solder bridge on a RottenDog power/driver board, bridging pins 3 and 4 on the DS1232 voltage watchdog, selecting 5% (4.75VDC) tolerance.]] 
RottenDog WhiteStar power/driver boards may have a solder bridge across pins 3 and 4 of the DS1232 voltage watchdog. This is done to prevent pin 3 from "floating" and instead actively select the watchdog voltage.

Quoting Ed from Great Plains Electronics on PinSide...

It appears pin 3 (voltage tolerance pin) was left floating on their (RottenDog) design. That input is supposed to be tied high (reset at 4.5V or 10% VCC tolerance) or tied low (reset at 4.75V or 5% VCC tolerance) and should never be left floating. Adding the jumper from pins 3 to 4 selects the 5% tolerance. If the 5V line dips below 4.75V then your board will reset (which is what it is supposed to do with that setting).

Jumpering pin 3 to pin 8 (5VDC) selects the 10% tolerance.
 

[[File:DS1232MPU.jpg ‎|left|thumb|300px|The MPU DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
[[File:DS1232Driver.jpg ‎|right|thumb|300px|The Driver board DS1232 voltage watchdog with pin 3 tied to 5VDC, selecting 10% (4.50VDC) tolerance.]] 
In these two images, the DS1232 voltage watchdog, pin 3, has been tied to a convenient source of 5VDC, selecting 10% (4.50VDC) tolerance.
 

[[File:WhiteStarModifiedDS1232.jpg ‎‎|left|thumb|300px|The DS1232 on a WhiteStar (modified) MPU, and connection that can be made.]] 
Some (if not all) WhiteStar (modified) MPUs leave pin 3 of the DS1232 floating. A trace from pin 3 leads to a through-hole for an unstuffed part. This through-hole can be exploited by adding a jumper as indicated in the picture at left. Installing this jumper configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance.
 

[[File:WhiteStarDriverRevGDS1232Connection.jpg ‎ ‎‎|left|thumb|300px|The DS1232 on a WhiteStar Revision G Driver Board, and connection that can be made to 5VDC, selectiong 10% tolerance or 4.5VDC.]] 
Revision G of the WhiteStar Power/Driver board leaves pin 3 floating even though R257 is provided to jumper the pin to ground. A better option is to jumper pin 3 to 5VDC which configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance. An easy method to achieve this is shown at left. This method uses the available through hole at R257.
 

==== Poor or Damaged Sockets Cause Reset ====
[[File:WhiteStarCrappySocketAnnotated.jpg‎|300px|thumb|left|A damaged EPROM socket from a Sega/Stern White Star MPU]] 
A damaged socket for either the game ROM or the 6264 RAM can cause a game to continually reset. This happens because the CPU can not fetch and execute instructions from the game ROM, or it is unable to read/write data to/from the RAM correctly. A simple replacement of damaged OEM sockets sometimes corrects a reset issue.
 

====Game Resets with DMD Controller Board Connected====
This may be a bit of an anomaly, but it is worth mentioning. If when the DMD controller board is connected without the data line ribbon cables, and the game continues to reset, replacement of BRDG21 may be required. 

In one particular instance, a game was resetting continually with only the +5v / ground connection connected to the DMD controller board. If the board was not connected, the driver board would output ~+5VDC. If the DMD controller board was connected, the driver board's logic line would dip down to around +4.85VDC. Logically speaking, this type of symptom somewhat points to the DMD controller board having issue. However, the end result was replacement of BRDG21 per Stern tech support. 

It is worth mentioning that the bridge rectifier did test correctly (using a DMM in diode test) both in circuit and out of circuit, but these tests were conducted while the bridge was not under load. 

===Solenoid/Flasher, and Controlled Lamp problems all at the same time===
[[File:CorrodedWhiteStarHeaderPinsCropped.jpg|300px|thumb|right|Corrosion on driver board header J1, prevented data bus signals from reaching the drive buffer chips. Image courtesy of PinSider JamesH007]] 
If the game is experiencing issues with multiple devices (coils, flashers, controlled lamps) that are controlled by the driver board, and those devices are "separated by 8 bits", there is a good chance that the data bus that connects to each of the 74HCT273s driver chips on the driver board has lost continuity somewhere between the associated MPU board dual row connector and the driver chips.

This can include:
*the dual row header on the MPU board
*the ribbon that connects the MPU and driver board
*the dual row header on the driver board
*the traces leading from the dual row header on the driver board to the 74HCT273s

The image at right shows a corroded connector which led to inoperative coils driven by Q3, Q11, Q19 and Q27 (note the gap between these parts is 8 transistors, the width of the data bus).
 

===Solenoid problems===

====Game Notes====
*NASCAR solenoid test swaps the order of output for coils 25 and 26. While the display calls out coils 25 and 26 correctly, in fact coils 26 and then 25 fire.

[[File:NASCAR-1.jpg‎|300px|thumb|left|NASCAR shooter lane switch with wireform correctly in place.]]
[[File:NASCAR-2.jpg‎|300px|thumb|right|NASCAR shooter lane switch with wireform bent/stuck and switch closed.]] 
Stern NASCAR, and possibly other games, use a switch in the shooter lane to detect the presence of a ball. If the switch is closed, and the auto-launcher coil fires to launch the ball, and the game doesn't detect that the switch has opened after firing the shooter lane auto-launcher, then the game assumes that the auto-launcher has malfunctioned in some way, and reports an error on the DMD.
 

====Testing MOSFETs and TIPs====
[[File:IO_test_points.jpg‎|300px|thumb|left|Driver Test Points TPL1 above Q16 (left) and TPL3 above R302 (right) are used to fire the transistors on the driver board.]] 

The Sega/Stern I/O Power Driver Board contains 32 driver transistors on the bottom right of the board. Transistors Q1-Q16 are MOSFETs – either 20N10Ls or P22NEs. These are used to drive high current coils like the flippers and other heavy loads. These are connected to devices through J8 and J9. Transistors Q17-Q32 are TIP 122s and are used for driving low power solenoids such as flash lamps. These are connected to devices through J6 and J7. 

All of these drivers are computer controlled directly from the CPU board through a flip-flop on the driver board. Q1-Q8 are controlled through U1 on the driver board, Q9-Q16 are controlled through U2, Q17-Q24 are controlled through U3 and Q25-Q32 are controlled through U4. Each one of these chips is selected by the address decoder at U204. There is another address decoder at U205 and both of these decoders must be working properly for the I/O board to function. 

It is possible to test the driver transistor and the solenoid in the circuit from the driver board. Above Q16 on the driver board is a test point marked “TPL1 FET”. Not a lot of people know what this is for. Per the manual: “This will apply 3.4v to the gate of the MOSFET transistor thus switching it on.” You’ll notice that the bank of resistors from R1 to R16 have a white stripe on one side closest to the MOSFETs. By using a jumper wire from TPL1 to the lug of each resistor in the white band, you can fire the coil associated with that resistor/MOSFET. Each resistor number corresponds with the same MOSFET number. So R1 fires Q1, R2 fires Q2, etc, etc. TPL1 is for testing all the FETs from Q1 to Q16. 

If you look in that same photo above R302, you will notice “TIP TPL3”. This serves the same purpose as TPL1 except for the TIP transistors on the driver board Q17-Q32. By jumping from TPL3 to the leg of the resistor in the white band, you can test each of the TIP122s and their associated circuitry. This is a useful diagnostic step if the machine will not fire a coil in self-test or during a game. If you can fire the transistor with this test, you know the problem is with the computer control circuitry for the solenoids. However, if it doesn’t fire, it could be a problem with the transistor or the associated components in that solenoid circuit. 

If one of Q1-Q16 is bad, it is best to replace it with an IRL540N (see below). If one of Q17-Q32 is bad, it is best to replace it with a TIP102. 
=====Screening Error On the Board=====
You might notice in the photo (prior section) that the white stripe is on the lower leg closest to the transistors of R1-16 and R25-32, but there is no white stripe on R17-24. Instead the stripe is on the lower leg of the resistors R200-R207. This is a screening error on the board but electrically match to the correct legs of resistors R17-24. As an example, if you want to test Q17, touch the leg of resistor R200 that’s in the white strip and Q17 should fire. The same holds true for R201/Q18, R202/Q19, etc etc. 

====Can an IRF540 replace a P20N10L, P22NE10L or an IRL540?====
[[File:IRL540vsIRF540.jpg‎|300px|thumb|left|Danger Will Robinson...the IRF540 installed at Q6 shown above, is the wrong part. The original 22NE10L should be replaced with an IRL540, like the one to it's immediate right.]] 
No.

The White Star driver board first used STP20N10L FETs to drive high current circuits, like solenoids. When they were discontinued later boards used the STP22NE10L. Since the 22NE10L is obsolete and even the current replacement, the
STP40NF10L is hard to find, the IRL540 or IRL540N are the recommended replacements. If available get the IRL540N because it has a higher drain current rating of 36A.
 While the drive specs of the IRF540 seem comparable, they are not. Using an IRF540 as a substitute can cause the associated coil to lock on, toast the coil, then blow the FET. The L in all of the original parts indicate that it is a logic level FET.

Per a good friend of Pinball, Ed Krzycki, via [http://groups.google.com/group/rec.games.pinball/browse_frm/thread/de777f6eec98a687/330e0d47fde12c6f?hl=en&lnk=gst&q=irf540# RGP post]...

''Nope -- an IRF540 is not a good sub for the IRL540 or 22NE10L.''

''The "L" parts have TTL compatible gate voltages. A TTL gate has a minimum high level output voltage of about 2.4 volts. To turn on any N-channel MOSFET transistor - the Gate voltage must be sufficiently high enough as listed by the spec sheets VGS(th) voltage.''

''The IRL540 requires a Gate threshold voltage of 1 to 2 volts. A TTL part exceeds this voltage so a TTL gate's high level output would guarantee the gate would turn completely on. The IRL540 is guaranteed to have "turn on" and "turn off" voltages that are compatible with a standard TTL device.''

''The IRF540 requires a Gate threshold voltage of 2 to 4 volts. A TTL gate *might* turn this part on if the specific part being used has a threshold in the 2 to 2.4 range. If the specific part being used has a threshold closer to the 4 volt range then the MOSFET probably won't turn on properly or fully. The IRF540 *might* work or it might not work. And no guarantees that a working part would remain working if ambient temperature changes.''

''Another aspect to an IRF540: An IRL540 operates more as an on-off switch but an IRF540 does not. Depending on voltages, an IRF540 can operate as an on-off switch and can also operate anywhere in between on and off (half on) depending on input voltage. If the TTL device cannot quite drive the gate voltage high enough then the MOSFET may end up partially conducting. This can have different results depending on how much it is turned on.''

''The 22NE10L has similar characteristics to that of the IRL540 as far as gate threshold voltages.''
 

====Adding a Real Knocker to White Star Games====

Some White Star games (like Starship Troopers) are not equipped with a real, old fashioned, knocker. We all love knockers, don't we?

To add a real knocker to your White Star game, follow this procedure.
Note: in this procedure, we locate the knocker in the head, attempting to increase the knocker's impact. For cabinet installation, take advantage of the wiring already provided for the European Token Dispenser.

[[File:AddingAKnockerBigPicture.jpg|left|300px|The objective...]] 
In the picture at left, we show all the components necessary to add a knocker. The new knocker is circled, top left. We've used an in-line connector along the wiring, also circled, lower left. The power and ground connections are noted by the rectangles.
 

[[File:SSTManual.jpg|thumb|left|300px|A snippet from the Sega Starship Troopers manual showing coils, and in particular, coil 8, the European Token Dispenser.]] 
First we need note that the European Token Dispenser solenoid drive is unused in domestic (USA) games. Coil power and drive connections are wired into the game. They can be found in the cabinet bottom. We could simply connect the knocker to that connection, but in this example, we mount the knocker in the game head.
 

[[File:SolenoidPowerConnection.jpg|thumb|left|300px|Adding a wire to provide the knocker with 50V power.]] 
Here I've stuffed another wire (yellow with purple tracer) on top of the solenoid power supply at J10, pin 5. This wire will eventually be connected to the banded side of the knocker coil.
 

[[File:SolenoidGroundConnection.jpg|thumb|left|300px|Adding a wire to provide a path to ground for the knocker, typically called the solenoid drive.]] 
Here I've stuffed another wire (purple with black tracer) on top of the solenoid 8 drive connection at J8, pin 9. This wire will eventually be connected to the non-banded side of the knocker coil.
 

[[File:SegaKnockerInSitu.jpg|thumb|left|300px|The new knocker, screwed to the cabinet upper left corner...not much room there. Also add the "strike plate" to the cabinet side.]] 
Of course, you need to procure the actual knocker hardware, and connect it as shown in the prior pics. In the picture at left, we've added a Sega knocker assembly and strike plate.
 

The last thing to do is to enter the game adjustments and turn the electronic knocker sound and the European Token Dispenser settings to off. On Starship Troopers, Enter Portals, Adjustments, Sega, and then adjustment 33 (Knocker Volume - set to OFF) and adjustment 40 (European Token Dispenser - set to OFF).

That's it. Enjoy those knockers!
 

===Flasher problems===
[[File:SSTFlashers.jpg|300px|left|thumb|One of the 4 sets of 4 colored flashers on Starship Troopers.]] 
Starship Troopers, Apollo 13 and perhaps other White Star games, drives 4 flash lamps via a single TIP-122 transistor. The TIP-122 is rated for a maximum drain of 8A (and a working current of 5A) while 4 flash lamps typically have a cold resistance of under 1 ohm (0.8 ohm is typical including wire and socket resistance.) While incandescent lamps only present their minimum resistance when extinguished (they are negative-temperature coefficient devices by design) the surge drain when these lamps are lighted radically exceeds the transistor's rating and is likely to damage or destroy it over time.

These channels should be replaced with TIP-102s (15A peak drain) or replace two (or more) of the flash lamps with LEDs to bring the drain in-line with the maximum ratings of the TIP-122.
 

===Controlled lamp problems===

==== Overview of The Lamp Matrix ====

The WhiteStar lamp matrix is an 8 column, 10 row lamp matrix, powered by 18V.

Lamp matrix power is derived from 13VAC presented to the I/O Driver board at J17, pins 8 and 9, via the transformer secondary winding. The circuit is fused by F22, an 8ASB fuse. BRDG20, a 35A bridge rectifier creates the 18VDC which is then smoothed by two 15,000uf/25V filter capacitors at C201 and C202. Of interest is the combined filtering of 30,000uf matches the original lamp matrix filtering capacity of old Williams System 3 games. When lit, LED202 indicates the presence of 18VDC power.

A blown fuse at F22 probably indicates a shorted bridge at BRDG20.

[[File:WhiteStarLampMatrixComponents.jpg|300px|thumb|left|Components of the WhiteStar I/O Driver Board Lamp Matrix]] 
Lamp rows are implemented with STP19N06L or STP20NF06L FETs, controlled by the 74HCT273 at U6 on the I/O Driver Board. 39K current limiting resistors protect the 74HCT273 from sinking too much power. The 74HCT273 is strobed (enabled) via the LMPSTB which originates at U205 (a 74LS138 at U205, pin 15).

If a STP19N06L (or STP20NF06L) transistor fails, it can be replaced with an IRL530N or an IRL540N. However, using an IRL530/540 has been known to create "ghosting" or "always dimly lit" behavior in the lamp row. If the original part can be obtained, this possibility can be eliminated. An IRFnnn (i.e. IRF530) or BUZ22 can not be used as a replacement.

Lamp columns are implemented by the obsolete VN02N PENTAWATT solid state relay (5 legs). They are controlled by the 74HCT273 at U18 on the I/O Driver Board. 18VDC is "strobed" to the lamp column headers. The 74HCT273 is strobed (enabled) via the LMPDRV which originates at U205 (a 74LS138 at U205, pin 13).

A replacement for the obsolete VN02N has not been identified. In addition to the WhiteStar I/O Driver board, VN02Ns were used on Capcom driver boards.

Be sure to check the fuse clips for the controlled lights. They go bad from either metal fatigue or they crack. This causes poor, erratic, or no connection with the fuse and thus, no lights.
 

===General illumination problems===

The four general illumination (GI) strings are turned on and off via the relay on the power driver board. On the White Star board the relay is controlled via transistor Q200 and latch U206. This is more or less the same setup found in earlier Data East and Williams System 11 games where the relay is located on the power supply or PPB board. These relays seldom fail. The part number for the 24VDC relay is any of the following:

*LB2-24DP (Great Plains Electronics number)
*190-5002-00
*LY2-0-DC24
*FRL264 P024/02CK
*R14-11D10-24P

If one or more GI strings are out check fuses F24 to F27 and then connector J15. Although WhiteStar GI connectors don't burn and tarnish like early Bally/Williams WPC GI connectors, checking both the male and female connectors at J15 is worthwhile.

[[File:Sega-whitestar-pdb-gi-error.jpg|300px|left|thumb|A leaky capacitor at C32]] 
If the GI goes out during game play and turns back on when opening the door, check capacitor C32 on the power driver board. It normally has nothing to do with either the GI circuit or the relay voltage but a leaking cap can short the trace coming from Q200 to ground. In this case the relay pulls in and disconnects the GI. When you open the door the game cuts the coil power for the relay coil and the GI turns back on. This has been observed in a Twister game.

The fuse clips for the GI circuits can fail, either by cracking or by losing their springiness.
This causes poor or no contact with the fuse and intermittent or no power to the associated GI string of lamps.
 

=== Switch problems ===

==== Overview of the Switch Matrix ====

The WhiteStar switch matrix is the typical 8 by 8, 64 switch matrix. As with other switch matrix implementations, isolation diodes are used on every switch in the matrix.

Switch columns (strobes) are connected to CN5 on the top edge, left side, of the CPU/Sound board. The columns are controlled by the 74HCT273 at U203 which sequentially controls an array of 8 2N3904 transistors. These transistors switch the 5VDC, normally held high via 560 ohm pull up resistors R423 through R430, to ground.

If a switch in the matrix is closed, the ground driven through the switch column will be presented at the row associated with the column/row intersection of that switch.

Switch rows (returns) are connected to CN7 on the top edge, right side, of the CPU/Sound board. 5VDC pull up resistors (560 ohms at R401 through R408) normally hold the switch row high. However, when the ground is presented at the row header of CN7, that 5VDC is pulled to ground. The signal is compared to 5VDC by the LM339 comparators at U400 and U401 with the result presented the the 74HC245 at U205 and then read via the 68B09E's data bus.

Note that the WhiteStar LM339 comparison implementation differs from the Bally/Williams WPC implementation which also uses 5VDC as a comparison voltage (reference) but compares that 5VDC to either 12VDC (open switch) or ground (closed switch).

==== General Switch Matrix Testing ====

[[File:WhitestarSwitchTest.jpg|thumb|300px|left|Testing Whitestar CPU/Sound board switch matrix circuitry with a jumper. A diode is not necessary.]] 
Like most modern game manufacturers, Sega/Stern games employ a switch matrix. The switch matrix circuitry on the CPU/Sound board may be tested (as pictured at left) by jumpering between switch row and switch column header pins while in switch test. This works with all versions of the Whitestar CPU/Sound board.

Note that some games, that do not use the full switch matrix, will fail to report a switch closure when jumpering row and column header pins for a switch that is shown as "not used" by the game. i.e. Sopranos does not use switch column 6. While a strobe is sent out on column 6, jumpering between column 6 and any row will not return a switch closure indication in switch test.

 

==== Playfield Switch Problems ====

===== Modular Stand Up Targets =====
The following Sega games employ unique playfield "Stand Up" targets:
*Goldeneye
*Twister
*Space Jam
*Star Wars Trilogy
*The Lost World Jurassic Park
*Starship Troopers
*Viper Night Drivin'
*Lost in Space
*Godzilla
*Harley-Davidson
*South Park
*Playboy (used behind the "Peek-A-Boo" stand up)

They are self-contained modular targets, made by Happ Controls, that are quite easy to remove or replace. The target "faces" may be purchased separately and may be interchanged easily. The unit has a self-contained diode, like all switches that are sensed via a switch matrix. It also contains a small micro-switch, that the "tail" of the target face actuates. The "Achilles Heel" of this target system is the IDC connector. As with all IDC connectors, the wires can pull out fairly easily. 

Detailed disassembly / assembly instructions can be reviewed in [http://www.pinwiki.com/wiki/images/7/76/Stern-Sb110.pdf Stern Service Bulletin 110]. 

<center>
<gallery widths=250px heights=200px perrow=3 caption="Sega Modular Targets (from Starship Troopers)">
File:SegaTargetFullyAssembled.jpg|<center>An example target. The target "faces" are interchangeable.</center>
File:SegaTargetParts.jpg|<center>"Exploded" target parts. The gray switch part must be oriented correctly. Note the integrated diode just under the micro-switch, center/bottom.</center>
File:SegaTargetIDCConnector.jpg|<center>The Achilles Heel of a Sega target...the IDC connector.</center>
File:SegaTargetDisassembly.jpg|<center>The first step to disassemble a target. Slide the rear face of the target assembly up.</center>
File:SegaTargetTestingZero.jpg|<center>Testing a closed target switch, step 1. In diode test, with the switch closed, your meter should read 0 or null.</center>
File:SegaTargetTestingDiodeDrop.jpg|<center>Testing a closed target switch, step 2. In diode test, with the switch closed, your meter should read .5 to .7, the nominal voltage drop across a diode.</center>
</gallery>
</center>
 

=====Magnetic Reed Switches=====

[[File:Placeholder.jpg|thumb|300px|left|Sega Magnetic Reed Switch (from Space Jam)]] 
Starting with Space Jam, Sega introduced magnetic reed switches. This type of switch is a sealed, non-serviceable switch. Theory of operation of the reed switch can be reviewed in [http://www.sternpinball.com/upload/downloads/sb89.pdf service bulletin 89]. Replacement part number is 180-5145-XX.
 

=====Ball Trough Switch Problems=====
[[File:White Star Trough 18 Nut.JPG|left|thumb|300px|Typical Sega ball trough assy. using 1/8" screws heads]]
[[File:White Star Trough 316 Nut.JPG|right|thumb|300px|Typical Stern ball trough assy.using 3/16" screws heads]] 
As with any sub microswitch, the switches can become sporadic or fail over time. Another thing that can happen is the switch arm can break at its pivot point. This happens with this style of switch more frequently than other styles, because the metal arm is placed between two plastic ears. With nearly every other style of sub microswitch, the arm has the metal ears which go over plastic nubs on the switch body. The correct replacement switches are 180-5119-00 roller arm switches. Over the years Sega / Stern used both 1/8" and 3/16" screw heads on the screws which secure the trough switches. At this time, it is uncertain when Sega / Stern changed the screw size. 

[[File:Xcelite 18 Nutdriver.jpg|left|thumb|300px|Xcelite 1/8" Nutdriver used to remove screws from trough switches]]
[[File:DE Ball Trough Divots.JPG|right|thumb|300px|Ball trough assembly with divots. Although it's not a White Star game, Jurassic Park is used for this example.]]
There may be other issues, which appear to act like ball trough switch failures. One of the problems is divots in the ball trough itself. After many iterations of the balls slamming into the trough over and over, divots start to develop. This divots can keep balls from rolling down the trough assembly. In turn, the balls will not be closing the proper switches in the trough. The end result is a game that "loses its mind". If the balls are not where they are expected to be in the trough, the game cannot function as intended. 

A similar issue to divots in the trough is magnitized balls. This occurs primarily in games where a magnet captures a ball and holds it for a length of time. Some examples of games with magnets that hold the ball are Apollo 13, Goldeneye, Twister, Space Jam, and X-Files. This problem typically happends when two or more balls are grouped together in the trough. They will literally be held in place and stick to the trough. This happens to the balls located furthest from the ball trough VUK. To determine if a ball or balls are magnetized, remove the lower apron, and the top bracket over the trough. Gently place a non-metallic object between the balls to see if they separate themselves.
 

For ball trough switch issues pertaining to the opto boards, see the section [[#Two_Balls_Served.2C_Continuous_Balls_Served_to_the_Shooter_Lane.2C_or_the_Trough_VUK_Fires_Repeatedly | below.]]
 

====Opto Switch Problems====
With White Star games, opto switch pair closures are analyzed by the CPU in the same manner as leaf switch pairs or normally open (NO) microswitches. When a leaf or NO microswitch closes, the end result is identified by the CPU as a valid switch closure.

[[File:Sega_X-Files_Optos.JPG|left|thumb|300px|Two sets of opto pairs installed in a Sega X-Files ]]
If an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch.

The transmitter side is an ultra-red LED with a current limiting resistor. The receiver is an identical ultra-red LED. When light from the transmitter shines on the receiver LED, a small amount of voltage is "excited" in the LED. By using discrete components on the receiver side, that small voltage is detected and the appropriate signal is sent to the CPU via the switch matrix return (row). In this design, failure on the receiver opto side is more common. The transmitter LED will be lit (and visible with the naked eye), while the receiver LED will not be lit.
 

<center>
<gallery widths=300px heights=150px perrow=3 caption="Sega/White Star Transmitter, Receiver, and Opto 'Long Hop' Board Pair, as found on Starship Troopers. Note that the ultra-red LED on the transmitter side is not lit until power is applied. The receiver side never illuminates.">
File:SegaOptoTransmitter.jpg|<center>The opto transmitter side.</center>
File:SegaOptoReceiver.jpg|<center>The opto receiver side, with accompanying electronics. The red colored LED is a diagnostic aid to indicate a detected switch closure.</center>
File:SegaOptoAlignment.jpg|<center>An opto pair. The pair must be in perfect alignment or the opto switch will operate unreliably.</center>
</gallery>
</center>
 

This particular system is different than how Bally/Williams WPC CPUs handle opto pairs. WPC games employ infrared opto pairs.

Theory of operation for these circuits is described in the manuals. Sega/Stern have included some excellent, detailed, technical documentation within their manuals. [https://www.pinwiki.com/wiki/images/9/92/Sb67.pdf Stern Service Bulletin #67] includes detailed theory of operation of these opto switches. 

=====Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly=====
Common problems with some White Star games are:
# Two balls are served to the shooter lane.
# Balls are continuously served to the shooter lane.
# The trough VUK repeatedly fires, when there are no balls above the VUK trough plunger.

The first test is to determine if the balls are sliding down the trough. If they are repeatedly magnetized they tend to stick to the side of the trough and not slide down. Replacing the balls with will fix this. There are balls available which are low magnetic, but you can also line the floor of the ball trough with a thin sheet of PETG breaking the magnetic contact.

Depending on the exact circumstances, and the era of the White Star game, one or two of these symptoms can occur. The crux of the problem is either one or both of the two trough LED opto transmitters or receivers is failing. Rarely do the components on the trough opto boards other than the red LEDs actually fail though. And in most cases, it is not the LED itself, although, there are some instances when the problem is a failing LED. It is noteworthy that the issue is more common to the opto receiver side more so than the opto transmitter side. 

[[File:Stern WS test trough 1 in trough.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough]]
[[File:Stern WS test trough vuk up one ball.JPG|left|thumb|300px|A Stern Monopoly in "Clear Ball Trough" Mode Identifying One Ball in the Trough and One Ball Stacked]]
If the any of the previously mentioned symptoms are evident, the best approach is to first put the game into "Clear Ball Trough" mode via the Portal buttons on the coin door. Consult the manual documentation for details how to enter this test. Once all of the balls are removed from the trough, no balls should display on the DMD display. If either of the two images shown to the left are displayed on the DMD, and the ball trough no longer has any balls present, there is a problem with either the transmitting or receiving opto boards.<br=clear all>

The first thing is to observe the two red opto LEDs on the transmitting board. This board is located on the backside of the ball trough. If the transmitting LEDs are lit, there probably is not a problem with them. However, this is not always necessarily the case. Secondly, inspect the opto LEDs on the receiving board. To do this, the game will have to be turned off, and the receiving opto board removed via the three screws which attach it to the trough. Look for hairline cracks around the .100" angled header pin solder joints. Likewise, inspect the solder joints around the opto LEDs. If cracks are evident in any of these locations, remove, and apply fresh solder to these connections. Reinstall the receiver board, and observe the results. Conversely, if hairline cracks are not found, or if the same symptoms are still evident after reflowing solder joints, replacement of the LED optos is suggested. 

White Star games initially used MT5000UR ultra-bright red LEDs, while later games used TLRH180P ultra-bright red LEDs for both the transmitter and receiver boards. Both styles of LEDs have become expensive and fairly difficult to source. Great Plains Electronics offers the [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] as viable replacement for either original, factory LED. The only caveat is that both the transmitter and receiver opto LEDs must be replaced in pairs to ensure proper function. 

When replacing the opto LEDs, make certain the base of the LED is placed squarely on the PCB. An LED which is poorly installed may result in sporadic switch closures. 

[[File:DE Trough Ball Lock3.JPG|300px|left|thumb|Lock Ball Assembly (from Jurassic Park - used for illustrative purposes)]] 
Please note that a "Lock Ball Assembly" was employed in the trough design on early White Star games. The lock ball assembly is a unit, which was carried over from later Data East and early Sega games. It consists of a coil mounted horizontally above the left side of the trough VUK. This assembly was later removed presumably either due to cost factors, or so this coil assignment could be used as a playfield coil feature elsewhere instead. 

If a lock ball assembly is used in the game, and trough opto failure has occured, the symptom will more than likely be that the trough VUK will fire repeatedly without a ball present above the VUK plunger.
 

=====Phantom Opto Switch Closures=====

Similar to the discussion above, "Two Balls Served, Continuous Balls Served to the Shooter Lane, or the Trough VUK Fires Repeatedly", other opto pairs in the game may fail over time and become unreliable. Usually this manifests as phantom switch closures. Games like Starship Troopers that use an opto pair for both the left and right orbit shots may score the orbit shot randomly or even continuously. If the "long hop" opto assembly is removed, you may find that the opto pair registers correctly if the optos are aimed with great accuracy at one another. However, the slightest misalignment (like flexing the PCB) will cause the opto pair to register a "hit".

The correction for this is again to replace the original MT5000UR or TLRH180P ultra-bright red LEDs, with [http://www.greatplainselectronics.com/search.asp?pg=1&stext=MV8114&sprice=&stype=&scat= MV8114] LEDs from Great Plains Electronics.
 

===Display problems===
A few of the many possible display problem root causes are...
*Failure in high voltage power supply
*Failed Dot Matrix Display
*Failed ribbon cable
*Failed power connector on display driver board
*Failed 74LS374 buffer IC on the MPU board

Each possible root cause is discussed below.

==== Measuring High Voltages for the DMD Display ====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|300px|thumb|left|Testing DMD Controller voltages at the display. Note: This picture is a Williams game, but the concept is the same.]] 
To test for the voltages necessary for the DMD to operate, first open the backbox, and rest the DMD panel face down on the glass. Or, if the game has a "Showcase" style head (i.e. StarShip Troopers), swing the panel open to gain access to the HV connection to the DMD. The simplest place to test the voltages is at the display end of the power wire bundle as shown in the picture. SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you! 

The dot matrix display needs three voltages to operate, nominally -112, -100, and 62 VDC. All three voltages must be present for the display to operate correctly.

Place the black lead of the DMM under the ground braid in the game's head or use clip leads to secure the black lead to ground. Remember, you are working one-handed, so this becomes a necessity. Place the red lead of your DMM on each of the pins supplying power as shown in the picture. As long as there is a 12VDC difference between the Anode and 12VDC offset voltages, your DMD controller is providing correct voltage levels.

{| class="wikitable"
!Function
! Pin 
! Spec 
! nominal voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>-120V</center> || <center>'''-112V'''</center> ||
|-
|  12VDC Offset  || <center>2</center> || <center>-100V</center> || <center>'''-100V'''</center> ||  Must be 12V less than anode voltage. Will be about 20V less than anode voltage if display not connected
|-
|  Key || <center>3</center> || || ||
|-
|  Ground || <center>4</center> || || ||
|-
|  Ground || <center>5</center> || || ||
|-
|  5VDC || <center>6</center> || <center>5V</center> || <center>'''5V'''</center> ||
|-
|  12VDC || <center>7</center> || <center>12V</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>60V</center> || <center>'''62V'''</center> ||
|}

If the high voltages are off by more than a few volts, turn the game off, disconnect the power connector at the HV Power Supply, and test the voltages at the HV Power Supply male header pins. If the voltages return to nominal values, the zener diodes on the power supply are probably OK but the resistors and transistors around them are suspect. As shown in the table above, if HV power is not connected to the display, the nominal 12VDC offset will be about 20VDC.

Note that a failing or failed DMD display glass can drag these voltages down. Before you begin any work on the HV Power Supply board, perform the above test with the DMD display power disconnected. If the voltages return to nominal values, it's possible that your display is the culprit. Test the high voltages with a known good display to isolate the fault to either the HV Power Supply or the display panel.

Should your HV Power Supply fail, the circuit is almost identical to the circuit used by Williams in their WPC DMD Controller. Similar parts are required to rehab the Sega/Stern HV Power Supply.

As of April 2014, schematics for the HV Power Supply are no longer available on Stern's site.

====Typical Failures of High Voltage Power Supply====
[[File:Stern WS DMD PSU.JPG|right|thumb|300px|A Stern 520-5138-00 Dot Matrix High Voltage Power Supply]]

'''The nominal output voltages of this board are shown below.''' 
The voltages measured between game ground and each pin of CN2 (right side as installed in the game).
*-110V on CN2-1
*-98V on CN2-2
*+5V on CN2-6 (piped directly through from CN1-7. This was a method of minimizing connector complexity)
*+12V on CN2-7 -- 20V is supplied at CN1-6 and is regulated down to +12V by VR1, a 7812. Note: the voltage at this pin will be missing if the board isn't stuffed with the 7812. It is not known when Stern/Sega stopped stuffing this location.
*+68V on CN2-8

The fuse on the board is a 3/4 ASB fuse.

'''Common failures:'''

*Fuse blowing
*-110V missing or too low
*-98V missing or too low
*+68V missing or too low

'''Solutions:'''

A blown fuse is indicative of a failed rectifier diode at D1 or D2 (1N4004. Anything from a 1N4005 to a 1N4007 can be used too). When D1 fails, Q1 and Q3 often fail along with it. When D2 fails, Q2, Q4, and Q5 often fail along with it.

*-120V problems are often caused by a failed transistor at Q2 (MPS-A42) and/or Q4 (MJE15031). When one of the transistors fails, often the other one fails too. Replace zener diode D4 (3.9V, 1N4730), D6 (100V, 1N4764A) and D7 (13V, 1N4743A) as well.

*-100V problems are often caused by a failed transistor at Q5 (MJE15030) or zener diode D6 (100V, 1N4764A). It's best to replace both. The 2k/5W resistor on R8 might also be the problem source, mostly due to failed solder contacts.

*+60V problems are often caused by a failed transistor at Q3 (MJE15030) and/or Q1 (MPS-A92) When one of the transistors fails, often the other one fails too. Replace zener diode D3 (3.9V, 1N4730) and D5 (68V, 1N4760A) as well.

As of 2014, schematics for the display power supply board are no longer available on Stern's website.

The Data East display power section of the 520-5047-01 and 520-5047-02 boards is an almost 1:1 copy compared to the one on this board. 

==== Failed Dot Matrix Display ====

A failed Dot Matrix Display will obviously cause display problems. Once you've tested for proper voltages, swap in a known good display, and swap the suspect display into a known working game. If the suspect display doesn't work in the known working game, it's time for a new DMD display.

==== Corrosion Under Header Pins ====

[[File:DESegaSternDMDControllerCorrosion.jpg|300px|thumb|left|Corrosion under the dual row headers of a DMD Controller board]] 
Corrosion from leaky batteries, being the bane of pinball PCBs, finds it's way to many places that might not normally be suspected. Sometimes, alkaline corrosion invades the header pin carriers, as shown in the picture at left. In this case, enough of the signals between the MPU board and the DMD controller board were corrupted to prevent proper rendering on the DMD display. Cleanup via typical methods restored this board to proper operation.
 

==== Failed ribbon cable ====

The ribbon cables on Sega/Stern White Star games connecting the CPU to the display controller are particularly long and twisted. There is ample opportunity for the ribbon cable to be damaged.

You should reseat the ribbon at both ends several times to knock off accumulated corrosion. This might temporarily solve the issue.

A simple test of the ribbon cable integrity would be to reverse it, causing the conductors used within the ribbon to be "swapped". Remove the ribbon from both ends, and instead of seating it with the red stripe at pin 1, seat the ribbon with the red stripe at the opposite end from pin 1. Make sure you reverse both ends of the ribbon. If the results witnessed on the display are then different, there is a good chance you need a new ribbon cable.

Gently bending and twisting the ribbon cables may help uncover intermittent connections and a compromised cable. Don't bend/twist too vigorously as this in itself may compromise the cable.

==== Failed power connector on display driver board (CN2) ====
[[File:CN2.jpg|300px|thumb|left|The '''craptastic''' 3 pin DMD Controller power header at CN2.]] 
Sega/Stern (and even Data East) made a poor decision for the power connection to the display controller. CN2 is a .156, 3 pin connector, which connects 5VDC and Ground to the display controller. The connector can be installed upside-down and reverse the 5VDC and Ground connections. This may kill the ROM chip and other chips on the board.

The solder joints for these header pins fracture often, or the pins in the female housing lose their grip (and hence connection). It is good practice to repin both sides of this connection, using crimp-on TriFurcon pins in the female housing.
 

==== Blank Display After "Splash Screen" Or Unusual Messages (Failed 74HCT273 buffer IC on the MPU board) ====

[[File:BadSchematicTableIndex.jpg|300px|thumb|left|One manifestation of a failed U201 or an open between U201 and the plasma display connector. Image courtesy of Chris Hibler.]]
The 74HCT273 at U201 on the CPU board buffers the output to the display controller via the ribbon cable. Should this IC fail, incorrect or no data will reach the display controller. Most of the time, this results in only the "splash screen" appearing which is displayed by the DMD controller on it's own, or in rare instances, the odd displays shown at left. First an over-scaled "Location ID:" image is displayed then "Bad Schematic Table Index!". This particular failure was caused by a corroded trace between U201 pin 2 and the via just northwest of pin 2. However, the same message may be displayed any time that the data path between U201 and the DMD Controller fails (i.e. poor header connections, failed ribbon cable).

U201 can be tested with a DMM following the process described [[General#Testing_an_integrated_circuit| here]].
 

====Display Issues Caused by Mismatched Game and Display ROMs====
[[File:WhiteStarEffectF7.jpg|300px|thumb|left|This message appears when the display controller software can't correctly decode display "calls" made by the MPU. Note that hexadecimal numbers other than "F7" may be displayed. Image courtesy of Chris Hibler.]]
Over the course of a game's manufacturing run, and even post production, game and display software was updated. It is important to ensure that the game ROM version is compatible with the display ROM version. Newer versions of the game code may request a display routine from the display controller that the display controller can not make sense of. When this happens, the display controller will display "Effect NN", where "NN" is the hexadecimal number of the display routine received.

Note that a less likely failure of IC U17 (a 74LS245) on the display controller board, which buffers inputs from the MPU, can cause the same or similar behavior. Corrosion on the ribbon header pins (both ends) or a faulty ribbon cable are other possible reasons for this message.
 

===Sound problems===

Before going any further, check all of the basics in the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section. 

'''Basic operation (simplified) of the White Star CPU/Sound board audio part:'''
The main CPU (U200) makes sound calls to the sound CPU (U6) which instructs the BSMT to play a certain sound. The BSMT fetches the required data (sound sample) from the ROM memory (U17-U21-U36-U37) and feeds the 16-bits wide parallel data to a conversion circuit which makes it serial data (shift register, U23-U24). The serial data is fed into a DAC (U26, Digital to Analogue Converter) that outputs to a pre-amplifier (U30, OPAMP). The output from the pre-amplifier is fed into the TDA2030A amplifiers at U101/U102 and sometimes U100 (some boards have 3 amplifiers, one for each speaker) and from there the audio signal goes to the speakers.

[[File:XilinxCPLD.jpg | thumb | right | 300px| The XC9572XLT Complex Programmable Logic Device. The yellow paint spot indicates that it has been programmed.]] 
The White Star (modified) version of the MPU board replaces almost all of the prior version's sound circuitry with 3 surface mount ICs.
*Xilinx CPLD at U414 (XC9572XLTQFP, T indicating the 100-pin version, QFP indicating Quad Flat Pack)
*Atmel RISC processor at U402 (AT91R40008)
*Atmel flash memory at U8 (AT49BV162AT)

The Xilinx CPDL ([https://en.wikipedia.org/wiki/Complex_programmable_logic_device Complex Programmable Logic Device]) is programmed by Stern (or it's board manufacturer) via the [https://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG] connector on the board.

The Atmel RISC processor ([https://en.wikipedia.org/wiki/Reduced_instruction_set_computing Reduced Instruction Set Computing]) replaces the 68B09EP of the prior board.

The Flash Memory contains the Sound Operating System. The correct version of the sound operating system my be "flashed" into the memory.
LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin #157]. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another). In April, 2016, "Chas" at Stern Pinball noted that sound operating system 8 (O/S 8) is backwards compatible with all WhiteStar (modified) games. It may even work with sound ROMs predating the WhiteStar (modified) board. However, there are known compatibility issues with early WhiteStar Sega games like StarShip Troopers.

The sound section of both board versions is quite reliable. The failure occuring most is a failed TDA2030A amplifier. If a sound problem can be isolated to one of the three fine pitch surface mount ICs on the WhiteStar (modified) board, the only option known as of April, 2016 is to return the board to Stern for repair. Stern does carry the parts necessary, but removal and replacement of such fine pitch parts is above the capability of most pinball hobbyists.

'''Sound missing from one of the speakers:'''
Possible failed TDA2030A amplifier.

'''No sound at all:'''
Check the voltages on the board. On the DC input connector CN2 there should be approx. +12V DC between pin 2 (ground) and pin 6 (+12V) and -12V between pin 2 (ground) and pin 3 (-12V), these voltages come from the Power Supply Board. On the board itself are two voltage regulators to convert the +12V and -12V to +5V and -5V for the pre-amplifiers, check these voltages by measuring between the ground (GND test point) and U30 pin 8 for +5V, U30 pin 4 for -5V.

Other causes of no sound at all are the U7 game ROM being corrupted or improperly seated. You can re-seat this ROM and it often solves the issue. If any of the voice ROMs (U17, U21, U36, U37) are corrupted or improperly seated, the sound will still work but will be corrupted or have intermittent issues such as scratchy sounds or improper sounds at specific times.

An incorrectly jumpered or installed RAM chip can also cause no sound. JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket).

Finally, if you have no sound at all, check that you have the correct sound board. Some operators may have swapped the Atmel based board with a BSMT2000 based board board for the older series White Star games. The Atmel based board will work in all White Star systems although some sounds may not be rendered correctly or at all. The BSMT2000 based board will work but will present no sound at all in all games newer than lord of the rings (2003).

'''Samples playing randomly'''
This happens on Whitestar (modified) CPU boards that emulate the BSMT2000 (which Stern could not source cheaply enough at the time). Reflashing the sound operating system firmware per Stern [https://sternpinball.com/wp-content/uploads/2018/10/sb157.pdf Service Bulletin 157] is recommended.

'''Sound is distorted'''
If the sound is distorted, a prime suspect is the TDA1543 (U26) chip. This sounds as if the volume is very over modulated and are “clipped”. Be sure to use the TDA1543 version and NOT the TDA1543A. The TDA1543A uses another protocol (Japanese). If the sound is distorted at master volume levels below 4, see the [http://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#Loud_Hum_and_.2F_or_Distortion_at_Low_Sound_Levels "Loud Hum and/or Distortion at Low Sound Levels"] section below.

'''Sound cuts out at the exact same point in a clip every time'''
If the sound consistently cuts out, or volume is lowered, or the clip is muffled, every time at the same point in the clip, there is a possibility that the 6116 RAM at U4 has failed.

'''Sound volume is extremely loud'''
Possible TDA1543 (U26) chip failure or counterfeit chip.

'''Loud hum'''
If there is a loud hum coming out of the speakers as soon as the game is turned on, make certain that the +12V is present.

'''Loud hum/burnt speakers/12V DC coming out of the speaker connector'''
If you have a machine with all speakers dead, check for voltage on the speaker wires. If the -12V wire from the driver board to the CPU board is disconnected, it can cause 12V DC to be sent down the speaker line, causing a loud hum and fairly quickly destroying any speakers connected!
 

'''Music Sounds Like Alvin and the Chipmunks'''
[[File:WhiteStarW6JumperLocation.jpg|left|thumb|300px|Schematic diagram showing the physical location of jumper W6 between the sound section 68B09E and the BMST2000, enabling the use of 8Mb EPROMs]] 
The original WhiteStar schematics mention jumper W6, which "must be installed for games that use 8Mb Sound EPROMs (U17 U21 U36 U37). For games which use 4Mb Sound EPROMs this jumper is not installed but 4Mb EPROMS will work on boards with W6 installed". This boils down to...install jumper W6. The manifestation of using 8Mb ROM images on a board with W6 not installed is sound that appears to be "Alvin and the Chipmunks"-like.

[[File:YT.png]] A YouTube video showing an incorrectly jumpered WhiteStar MPU with Harley Davidson ROMs can be found [https://youtu.be/7MXxngST5g4 here].

Note that the WhiteStar (modified) MPU board does not provide jumper W6, nor is it needed. The WhiteStar modified board works with both 4Mb and 8Mb sound ROMs, as if W6 was installed.
 

====Sound Section Jumper Settings====
JMP5 should be installed and JMP4 removed when a 6116 is used. JMP4 should be installed and JMP5 removed when a 6264 is used. JMP4 and JMP5 are just above U7 (Sound ROM code) and U4 (RAM socket). An incorrectly jumpered or installed RAM chip can result in no sound at all.

'''Important:''' Under normal operation...
*JMP2 should be on the right pair of pins
*JMP3 should be on the top pair of pins, and
*JMP4 should be on the bottom pair of pins.

Placing the jumpers in any other position will cause sound to be missing. These jumpers are provided to update the sound operating system within the flash memory at U8.
 

====Loud Hum and/or Distortion at Low Sound Levels====
[[File:SternServiceModForLowSoundLevels.jpg|300px|thumb|left|Trim POTs connected across R106 and R110. This mod was offered by an aftermarket seller. Image courtesy of Jack Jarrett]]
[[File:WhiteStarResistorHack.jpg|300px|thumb|right|Trim POTs connected across R106 and R110 in a rather kludgy way...but it works. Image courtesy of PinSider Capt_Pinball]] 

Stern released [http://www.sternpinball.com/upload/downloads/sb133.pdf Service Bulletin 133], which discusses a fix for a loud hum and / or distortion when the master volume is set below level 4. The machines that are specifically effected are Monopoly and Austin Powers. However, it has been over 10 years since these games have been released, and boards get transplanted to other games over time. So, it is important to check the two resistors (R106 and R110) in the amplification section of the CPU / sound board to see if the correct values are installed, regardless of the game. The correct resistor values should be 33K ohms 1/4 watt for R110 (ORG-ORG-ORG-GOLD), and 10K ohms 1/4 watt for R106 (BRN-BLK-ORG-GOLD). Consult the service bulletin for more details, and the layout of the amp section. The R106 and R110 control the analog volume. When these resistors are broken (open) the analog volume goes to 100% and can't be controlled via the buttons (digital volume) on the coin door. The higher the resistor value the higher the volume.

Another method of accomplishing the same thing, without removing and replacing a resistor, is to add a resistor to the back of the board, across R106 and R110, creating the equivalent resistance as mentioned above. A 4.7K resistor seems to be a sweet spot.

Yet another method used is to clip a 10K trim pot across each resistor as shown in these images. The trim pot can be adjusted to a good compromise between hum and volume.
 

==== Low Background Sound Volume ====
[[File:WhiteStarBackgroundSoundVolume.jpg|300px|left|thumb|Background sound level setting on Roller Coaster Tycoon]] 
Some games, at least Viper Night Drivin' and Roller Coaster Tycoon, provide a means of adjusting the level of the background sound. The sound can be adjusted from level 1 (loudest) to level 15 (lowest).
 

====Adding a Second Backbox Speaker to some Sega Games ====
[[File:NewSpeakerAndSpeakerBlank.jpg|300px|left|thumb|Adding a second backbox speaker may improve the sound in games shipped with a single backbox speaker. Buy the speakers in pairs. This image shows the new speaker installed onto the left speaker bracket, and the right speaker position "blank" from a StarShip Troopers game. The "blank" must be modified so that the new speaker can be attached.]] 
A chap named Martin Riley submitted a nice article to the PinballNews explaining how to add a second backbox speaker to games like StarShip Troopers.

From the article... 
"Mid-life Sega games from Twister through to and including Viper Night Drivin' only had the left hand backbox speaker plus the cabinet speaker and only two of the 3 audio amps are populated on the CPU board.

Late Sega games from Lost in Space onwards have two backbox speakers but they are effectively mono as they are both connected to the left channel audio amp on the CPU board (the right channel amp being unpopulated)."

The complete article can be found at http://www.pinballnews.com/learn/speaker/index.html

The article lists all components required to add the 3rd speaker channel. Some (maybe all) two channel boards are not stuffed with C122, which is not listed in article parts list. You'll need one more 0.1µF axial ceramic capacitor for C122.

Adding a 3rd speaker to StarShip Troopers improved the sound quite a bit. The sound is richer and cleaner. The emphasis on some sounds is more pronounced and easier to hear. Edit: months later, I was testing a board in my StarShip Troopers that didn't have the 3rd amp. Forgetting that I had added the 3rd amp to my MPU, I initially thought something was wrong with the sound that the MPU under test was producing. It was merely the difference between a single and dual backbox speakers.

Mounting the additional speaker to the "blank plate" (as found in StarShip Troopers) required drilling the rivets that attach the speaker grill, and replacing them with low profile head screws. This is only necessary for Sega "Showcase" backbox games. For games like Independence Day, mounting the additional speaker should be trivial.

 

==== Is a Second Backbox Speaker Really Worth It? ====
While some have reported good results adding a third amp and second backbox speaker to these early Sega games, there are questions about the efficacy of such a solution. While better speakers themselves will improve the sound, the game-specific sound samples in the ROMs are mastered as mono sound clips. There are very few sounds in the game that are true stereo sound and these are usually simple sound effects which were used in multiple games. 

You can listen to and judge for yourself by running the Bridge front end and the M1 MAME music player. Bridge and links to the M1 player can be found [http://www.e2j.net/downloads.html here]. 

The mono mastering continued through the White Star II and SAM systems. As David Thiel, who has created music and sound for numerous Data East and Stern pinball machines, states on this [http://daudioguy.multiply.com/video/item/5/Family_Guy_Stern_Pinball_Music_and_Sound_Effects_by_David_Thiel?&show_interstitial=1&u=%2Fvideo%2Fitem page] of his website, he "composed, arranged, performed, mixed and mastered (all the music for Family Guy) for 24 kHz 16 bit Mono." 

===Flipper problems===
====Non-Functioning Flippers====
====Weak Flippers====
=====Progressively Weak Flippers=====

==Game Specific Problems and Fixes==
'''Lord Of The Rings''' 

If your Balrog stops registering hits, a little checking will sort it out. The mini microswitch with a roller arm used to register hits may need adjusting. Known past problems are a flaky or bad switch, and/or wiring. The Balrog moves in such a way that wires can break inside where you can't readily see them. It's easy to check the switch and wires with a meter. The wires push into an IDC connector nearby; be sure they are pushed in tight.

There isn't any adjustment for the micro switch, except for bending the blade with the mini-roller; try bending the blade outwards slightly. According to the manual, sw #28 stays normally closed and then a Balrog hit opens the switch. This is not the normal target arrangement. So using the Balrog test mode in diagnostics, the switch should stay solidly closed, and then only open when Balrog is tilted forward.

'''The Shire and Gimli VUK switches.''' 
These get hammered on LOTR and will eventually need replacing, There isn't any easy solution other than replacing the flaky switch. The tiny black screws on the Stern switches are 3/16". You will need a nut driver that size if you want to attempt replacement of the switches.

The Shire (and Gimli) VUK switch, are fork blade microswitches. Stern part number 180-5116-01. 
Spec on side of switch says Cherry .1A 125v E63. Try parts4pinballs.com or your favorite Stern parts supplier.

The Shire VUK. 
It's easiest to remove the entire Bottom Left VUK coil and bracket from under the PF (playfield) to change the fork switch. 
Take out the two largest bolts first, using a cross-head (phillips) screwdriver on the top and 11/32" nut runner (or socket) on the bottom. 
Remove the metal VUK arch from the top of the playfield. 
Remove the two lower wood screws (1/4" drive) leaving the one on the corner near the T-nut. 
Supporting the Coil Bracket, remove the last 1/4" screw. 
Unclip the connector from the coil and VUK. Remove coil and bracket assembly. 

Microswitch small screws are 3/16". As stated before, to remove the switch correctly you need a nut driver (or socket) that size.
You should be able to slide the heatshrink tubing all the way up the wires, solder on the new switch and then slide them back down in place. If not, use new heatshrink tubing. Assembly is above steps in reverse. Test in switch tests before replacing assembly and then by throwing a ball in the Shire in attract mode one the assembly has been correctly replaced.
 

'''Ripley's Believe it or Not! and The Simpsons Pinball Party''' 
Not certain what code versions apply with this. When the coin door is open, and the first ball drains, the game will not recognize that the ball has drained at all. Likewise, it will not kick the next ball over to the shooter lane. This is even with the solenoid voltage interlock switch pulled out. It is presumed that the memory lock switch has to be closed for the game to function properly.

This may apply to more games of this vintage other than just these two!
 

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.

*'''Striker Xtreme:'''
**Problem: '''Display is blacked out or only coming on for a few seconds before blanking out.'''
**Cause: Resistors R6 and/or R7 on the display power supply board have gone bad (open or increased in value).
**Solution: Replace resistors R6 AND R7 on the display power supply board. Both are 330k @ 1/2 watt
*'''Simpsons Pinball Party:'''
**Problem: '''When last ball drains, game still thinks its in play.''' Ball search or power cycle will eventually find it.
**Cause: Cracked solder joint on trough board.
**Solution: Pull both trough boards. A 1/4" wrench can be useful in getting the back board off. In this case, the obviously cracked solder connection was on the receiver board in front. But while the board is out, the optos were cleaned with Windex.
**This can be verified by waiting for the problem to show up, then go into switch test. Previously, switch #5 (leftmost) had been suspected and had been re-aligned, but that was probably not necessary.
*'''Starship Troopers, but applies to all:'''
**Problem: '''No display, no sound, upper amplifier went up in smoke.'''
**Cause: Connector CN4 on MPU / Sound board and CN1 of display power supply board were swapped. Both CN4 and CN1 are keyed the same. In haste, these connectors can be mixed up. Keep in mind that the speaker output is a very light gauge wire versus the heavier gauge for the display power supply input.
**Solution: This was not as bad as expected. After studying the schematics, only +20V (CN1 pin 6 - pin 4 is GND on both connections) can potentially backfeed through the sound circuitry. Amplifier U101 failing spectacularly possibly prevented additional damage. Amps U101 and U102 were replaced (U100 was not stuffed on this board). After replacing the amps, sound came back, but was very faint. Further investigation revealed 3 100Kohm resistors had failed, R21, R22, and R24. Also, U26, the TDA1543 DAC, had also failed.
*'''Goldeneye, but applies to all:'''
**Problem: '''Blanking signal OK but driver board blanking LED keeps blinking.'''
**Cause: Ribbon cable from MPU to driver board faulty.
**Solution: Replace ribbon cable.
*'''Goldeneye, probably Twister:'''
**Problem: '''Magnets don't work, MAG2 LED on magnet board keeps blinking in test mode.'''
**Cause: Bad connection from magnet board to magnet between flippers.
**Solution: Fix connection.

Stern SPIKE™ System Repair

2023-03-20T21:09:28Z

Jimpal: /* SPIKE 2 */

{{WIP}}

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

= Stern SPIKE™ System Repair =

==Introduction==
The SPIKE™ System is the current board system used by Stern Pinball. The first full production game to use the SPIKE Board Set was Wrestlemania in 2015. The SPIKE architecture is a large departure from prior board set architectures. Per Stern, "The SPIKE Pinball system is rugged, distributed, and embedded platform custom-designed for the rigors of the pinball machine environment".

The SPIKE system is comprised of a CPU board and a series of several "node boards" that are powered from a 48VDC power bus. Each SPIKE "node board" will regulate this 48VDC down to the proper voltage required to operate the "devices" under control of that node (lamps, coils, switches, etc). Nodes are connected with standard CAT 5e (or better) 8 conductor Ethernet wiring although the interface protocol is '''not''' Ethernet, and connecting a SPIKE node to computer Ethernet will damage the board (per Stern). There are several node boards mounted to the bottom side of the playfield to control the various lamps, coils, and switches on the playfield. There is one "cabinet" node board located next to the plumb bob tilt assembly which controls start button, tilt, coin door, diagnostic switches, dollar bill acceptor, shaker motor, ticket dispenser, coin meters, etc.

==Games==
===SPIKE 1===

{| class="wikitable"
! Date
! Name
! Pro
! Premium
! Limited Edition
|-
| 2012 || [[Transformers, The Pin]] || colspan="3" | One Model
|-
| 2013 || [[Avengers, The Pin]] || colspan="3" | One Model
|-
| 2015 || [[Wrestlemania]] || Yes || No || Yes (400 max)
|-
| 2015 || [[Whoa Nellie! Big Juicy Melons™]] || colspan="3" | One Model
|-
| 2015 || [[KISS]] || Yes || Yes || Yes (600 max)
|-
| 2015 || [[Game of Thrones]] || Yes || Yes || Yes (700 max)
|-
| 2016 || [[Ghostbusters]] || Yes || Yes || Yes (500 max)
|-
| 2016 || [[Pabst Can Crusher]] || colspan="3" | One Model
|-
| 2016 || [[Spider-Man, The Pin]] || colspan="3" | One Model
|-
| 2018 || [[Primus]] || colspan="3" | One Model
|-
| 2018 || [[Supreme]] || colspan="3" | One Model
|}

===SPIKE 2===

{| class="wikitable"
! Date
! Name
! Pro
! Premium
! Limited Edition
! Other Models
|-
| 2016 || [[Batman 66]] || No || Yes || Yes (240 max) || Super LE (80 max)
|-
| 2017 || [[Aerosmith]] || Yes || Yes || Yes (500 max) ||
|-
| 2017 || [[Star Wars (Stern)]] || Yes || Yes || Yes (800 max) ||
|-
| 2017 || [[Guardians of the Galaxy]] || Yes || Yes || Yes (600 max) ||
|-
| 2018 || [[Iron Maiden (Stern)]] || Yes || Yes || Yes (500 max) ||
|-
| 2018 || [[Deadpool]] || Yes || Yes || Yes (500 max) ||
|-
| 2018 || [[Beatles]] || Gold (1614 max) || Platinum (250 max) || Diamond (100 max) ||
|-
| 2019 || [[The Munsters]] || Yes || Yes || Yes (600 max) ||
|-
| 2019 || [[Black Knight: Sword of Rage]] || Yes || Yes || Yes (600 max) ||
|-
| 2019 || [[Jurassic Park (Stern)]] || Yes || Yes || Yes (500 max) ||
|-
| 2019 || [[Star Wars Pin]] || colspan="4" | One Model
|-
| 2019 || [[Elvira's House of Horrors]] || No || Yes || Yes (400 max) || Signature Edition (50 max), 40th Anniversary Edition (199 max) released 10/2021
|-
| 2019 || [[Stranger Things]] || Yes || Yes || Yes (500 max) ||
|-
| 2020 || [[Heavy Metal]] || colspan="4" | One Model
|-
| 2020 || [[Teenage Mutant Ninja Turtles (Stern)]] || Yes || Yes || Yes (500 max) ||
|-
| 2020 || [[The Avengers Infinity Quest]] || Yes || Yes || Yes (500 max) ||
|-
| 2020 || [[Led Zeppelin]] || Yes || Yes || Yes (500 max) ||
|-
| 2021 || [[Star Wars The Mandalorian]] || Yes || Yes || Yes (750 max) ||
|-
| 2021 || [[Godzilla]] || Yes || Yes || Yes (1000 max) ||
|-
| 2021 || [[Jurassic Park Pin]] || colspan="4" | One Model
|-
| 2022 || [[Rush]] || Yes || Yes || Yes (1000 max) ||
|-
| 2022 || [[James Bond 007]] || Yes || Yes || Yes (1000 max) || 60th Anniversary LE (500 max)
|-
| 2023 || [[Foo Fighters]] || Yes || Yes || Yes (1000 max) ||
|}

==Technical Info==
===The SPIKE Board Set===

Stern has issued a technical video discussing the Spike 1 system boards: https://www.youtube.com/watch?v=MvefdrNaAPg 
There is a well done video by Stern, featuring George Gomez, describing the Spike 2 system boards: https://www.youtube.com/watch?v=d1xdmgeAylQ&t=190s
[[File:Ghostbusters_Spike1_board.JPG|200pix|thumb|left|Ghostbusters Spike 1 board]] 
Spike 1 CPU board installed in a Ghostbusters.

 

===Recommended Documentation===

====Manuals====
As always, it is highly recommended to possess a game manual. Every game manual is full of detailed information regarding game specific switch, lamp, and coil assignments. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included.

The most current versions of the game manuals are posted on [https://sternpinball.com/support/game-manuals/ Stern's website in the support section].

* Wrestlemania manuals - [https://sternpinball.com/wp-content/uploads/2018/11/WWE-PRO-MAN-1.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/11/WWE-LE-Manual.pdf LE]

* [https://sternpinball.com/wp-content/uploads/2018/11/Whoa-Nelly-Manual.pdf Whoa Nellie game manual]

* KISS manuals - [https://sternpinball.com/wp-content/uploads/2018/11/KISSProweb.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/11/KissPremiumweb.pdf Premium], [https://sternpinball.com/wp-content/uploads/2018/11/KissLEweb.pdf LE]

* Game of Thrones manuals - [https://sternpinball.com/wp-content/uploads/2018/11/GameOfThrones_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/11/GameOfThrones_LE_Prem_web.pdf Premium & LE]

* Ghostbusters manuals - [https://sternpinball.com/wp-content/uploads/2018/10/Ghostbusters_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/10/Ghostbusters_LE_web.pdf Premium & LE]

* Batman '66 manuals - [https://sternpinball.com/wp-content/uploads/2023/01/Batman_LE_Pre_web.pdf Premium & LE], [https://sternpinball.com/wp-content/uploads/2023/01/Batman_SLE_web.pdf Super LE]

* Aerosmith manuals - [https://sternpinball.com/wp-content/uploads/2018/10/Aerosmith_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/10/Aerosmith_LE_Pre_web.pdf Premium & LE]

* Star Wars manuals - [https://sternpinball.com/wp-content/uploads/2018/10/StarWars_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/10/StarWars_LE_Pre_web.pdf Premium & LE], [https://sternpinball.com/wp-content/uploads/2020/01/StarWarsComic_Pro_web.pdf Comic Pro], [https://sternpinball.com/wp-content/uploads/2020/01/StarWarsComic_LE_Pre_web.pdf Comic Premium & LE]

* Guardians of the Galaxy manuals - [https://sternpinball.com/wp-content/uploads/2018/09/Guardians_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/09/Guardians_LE_Pre_web.pdf Premium], [https://sternpinball.com/wp-content/uploads/2018/09/Guardians_LE_Pre_web-1.pdf LE]

* Iron Maiden manuals - [https://sternpinball.com/wp-content/uploads/2018/10/IronMaiden_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/10/IronMaiden_LE_Pre_web.pdf Premium & LE]

* Deadpool manuals - [https://sternpinball.com/wp-content/uploads/2018/09/Deadpool_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2018/12/Deadpool_LE_Pre_web.pdf Premium & LE]

* Beatles manuals - [https://sternpinball.com/wp-content/uploads/2019/02/Beatles_web.pdf Gold/Platinum/Diamond]

* The Munsters manuals - [https://sternpinball.com/wp-content/uploads/2020/02/Munsters_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2020/02/Munsters_LE_Pre_web.pdf Premium & LE]

* Black Knight: Sword of Rage manuals - [https://sternpinball.com/wp-content/uploads/2019/05/BlackKnight_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2019/07/BlackKnight_LE_Pre_web.pdf Premium & LE]

* Jurassic Park manuals - [https://sternpinball.com/wp-content/uploads/2022/11/JurassicPark_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2022/11/JurassicPark_LE_Pre_web.pdf Premium & LE]

* Star Wars The Pin - [https://sternpinball.com/wp-content/uploads/2020/12/StarWars_Pin_web.pdf Manual]

* Elvira's House of Horrors - [https://sternpinball.com/wp-content/uploads/2019/10/Elvira_LE_Pre_web.pdf Premium, LE, & SE]

* Stranger Things manuals - [https://sternpinball.com/wp-content/uploads/2020/01/StrangerThings_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2020/01/StrangerThings_LE_Pre_web.pdf Premium & LE]

* Teenage Mutant Ninja Turtles manuals - [https://sternpinball.com/wp-content/uploads/2020/07/TMNT_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2022/11/TMNT_LE_Pre_web.pdf Premium & LE]

* The Avengers: Infinity Quest - [https://sternpinball.com/wp-content/uploads/2020/09/AvengersInfinity_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2020/09/AvengersInfinity_LE_Pre_web.pdf Premium & LE]

* Led Zeppelin - [https://sternpinball.com/wp-content/uploads/2021/01/LedZeppelin_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2021/01/LedZeppelin_LE_Pre_web.pdf Premium & LE]

* The Mandalorian - [https://sternpinball.com/wp-content/uploads/2022/05/Mandalorian_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2022/05/Mandalorian_LE_Pre_web.pdf Premium & LE]

* Godzilla - [https://sternpinball.com/wp-content/uploads/2022/05/Godzilla_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2022/05/Godzilla_LE_Pre_web.pdf Premium & LE]

* Jurassic Park The Pin - [https://sternpinball.com/wp-content/uploads/2022/04/JurassicPark_Pin_web.pdf Manual]

* Rush - [https://sternpinball.com/wp-content/uploads/2022/05/Rush_Pro_web.pdf Pro], [https://sternpinball.com/wp-content/uploads/2022/08/Rush_LE_Pre_web.pdf Premium & LE]

====Schematics====

=====SPIKE 1=====

{| class="wikitable"
! Game
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6936-01B-CPU-SPIKE-1-.pdf 520-6936-01] or 520-6936-10 SPIKE-1 CPU Node Board
! 520-5319-00 Cabinet Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6967-72D-CABINET-NODE-BOARD-72Mhz-expanded.pdf 520-6967-xx] Cabinet Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6935-10E-8-COIL-PLFD-NODE-BOARD-4K.pdf 520-6935-10] 8-Coil Playfield Node Board
! 520-6985-72 8-Coil Playfield Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-5322-72H-32-SW-LMP-EXPANSION-BRD-72Mhz.pdf 520-5322-xx] 32-Light & Switch Node Board
! 520-5329-10 4-Coil Playfield Node Board
! 520-5345-01 Trough Serial Opto Receiver Extension Board
! Topper
! Misc.
|-
| Whoa Nellie || Node 0 || Node 1 || || Node 8 || || Node 10 || Node 9 & 11 || || ||
|-
| KISS Prem/LE || Node 0 || Node 1 || || Node 8, 9, & 10 || || Node 11 || || 8a || ||
|-
| Game of Thrones Prem/LE || Node 0 || || Node 1 || Node 8 & 11 || || || Node 9 & 10 || 8b || ||
|-
| Ghostbusters Prem/LE || Node 0 || || Node 1 || || Node 8 & 9 || || Node 10 || 8a || Node 12 (optional) || Node 24 - 520-6988-00 LCD Node (Ecto Goggles)
|}

=====SPIKE 2=====
Some Stern Spike schematics can be found [https://sternpinball.com/support/ here]. 
{| class="wikitable"
! Game
! 509-1000-00 SPIKE-2 CPU Node Board
! 509-1003-01 SPIKE-2 CPU Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6967-72D-CABINET-NODE-BOARD-72Mhz-expanded.pdf 520-6967-xx] Cabinet Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-7017-72D-Core-Node-Hall-3amp.pdf 520-7017-72] or 520-1057-00 8-Coil Playfield Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6998-72C-4-COIL-PLFD-NODE-BOARD-Plus.pdf 520-6998-72] 4-Coil Playfield Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6976-72A-SPI-only-NODE-board.pdf 520-6976-72] SPI Core Playfield Node Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-7001-00A-TROUGH-RECEIVER-BOARD.pdf 520-7001-00], 520-7001-00, 520-1051-00, or 520-8516-00 Trough Serial Opto Receiver Extension Board
! [https://sternpinball.com/wp-content/uploads/2019/02/520-6996-00A-Serial-Motor-Controller-4-way-functionality.pdf 520-6996-00A] Motor Driver Board
! Topper
! Misc.
|-
| Batman 66
| Node 0
|
| Node 1
| Node 8 & 9
|
|
| 8a
| 9c
|
| Node 10 - 520-7019-72 Turntable Node, Node 24 - LCD Node (Villain Vision)
|-
| Aerosmith
| Node 0
|
| Node 1
| Node 8 & 9
|
|
| 8a
| 8e
|
| Node 10 - 520-5329-10 Playfield 48V 4-Coil node board (Prem/LE only)

|-
| Star Wars (Pro)
|
| Node 0
| Node 1
| Node 8 & 9
|
| Node 10
| 8a
|
|
|
|-
| Star Wars (Prem/LE)
|
| Node 0
| Node 1
| Node 8 & 9
| Node 11
| Node 10
| 8a
| 9d
|
|
|-
| Guardians of the Galaxy (Pro)
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Guardians of the Galaxy (Prem/LE)
|
| Node 0
| Node 1
| Node 8 & 9
| Node 11
| Node 10
| 8a
| 9b
|
|
|-
| Iron Maiden (Pro)
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Iron Maiden (Prem/LE)
|
| Node 0
| Node 1
| Node 8 & 9
|
| Node 10
| 8a
|
|
|
|-
| Deadpool
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Beatles
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Munsters
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Black Knight: Sword of Rage
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Jurassic Park (Pro)
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|
|-
| Jurassic Park (Prem/LE)
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
| 9b
|
| Node (unlabeled) - 520-8424-00 - (Back panel) Stepper Motor Driver board
|-
| Star Wars The Pin
|
| Node 0
|
| Node 8
|
|
| 8c
|
|
|
|-
| Elvira's House of Horrors
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) [https://sternpinball.com/wp-content/uploads/2019/02/520-6998-72C-4-COIL-PLFD-NODE-BOARD-Plus.pdf 520-6998-72]
|
|-
| Stranger Things
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|Node 12 (optional)
|Node 9a1 - 520-8418-00 - Dual Motor Driver Lamp board
|-
| Heavy Metal
|
| Node 0
|
| Node 8
|
|
| 8c
|
|
|
|-
| Teenage Mutant Ninja Turtles
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
|
|Node 9a5 - 520-8418-00 - Motor Driver Board-Lamp Drive (Prem/LE only)
|-
| The Avengers Infinity Quest
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) 520-6976-72
| Node 8c - 520-8466-00 - Magnetic Angle Sensor
|-
| Led Zeppelin
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) 520-8087-72
| Node 2 (optional) - 520-8087-72 - SPI Node-PWM - Cabinet Lighting
|-
| The Mandalorian
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) 520-8530-00 HDMI Adapter-Topper
|
|-
| Godzilla
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) 520-8511-00
| Node 4 - 509-2020-00 - QR Reader Node Node 10 - 520-5781-02 - Stepper Motor (Prem/LE only)
|-
| Jurassic Park The Pin
|
| Node 0
|
| Node 8
|
|
| 8b
|
|
|
|-
| Rush
|
| Node 0
| Node 1
| Node 8 & 9
|
|
| 8a
|
| Node 12 (optional) 520-6998-72
| Node 4 - 509-2020-00 - QR Reader Node Node 2 (Optional) - 520-8511-00 - Expression Lighting Node 9a4 - 520-8543-00 - Time Machine PCB (Prem/LE only) Node 10 - 520-5781-02 - Stepper Motor (Prem/LE only)
|}

Notes:
# 509-1000-00 replaced by 509-1003-01
# For the Star Wars Pin (Home Edition), Node 8 subsumes the functions performed by the cabinet node board (typically Node 1 on other Spike machines).
# As per a [https://sternpinball.com/wp-content/uploads/2022/09/Stern-NodeBoardUpdate.pdf service released in September 2022], node board 520-7017-72 (blue board) is being replaced by 520-1057-00 (green board). The boards were stated to be interchangeable.

 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===

[[File:Ghostbusters_coin_door.JPG|200px|thumb|left|Ghostbusters coin door pushbuttons]] 

 

Spike system games use four pushbutton switches (located on the coin door) to access the bookkeeping, adjustments, and diagnostics very much like Williams WPC series machines do. The black pushbutton enters the menu while the two red + and - pushbuttons step you through the menu (also act as volume up and volume down). If you want to go backwards, push the green button (it acts like "escape" function).

===Node Board Information===

Node board library.

====SPIKE 1 CPU - 520-5318-01====
[[file:SPIKE0MPU.jpeg|left|thumb|300px|Node Board 0, part number 520-5318-01.]] 
Node 0 in the backbox. Used in the home version "The Pin" games: Avengers/Transformers The Pin
 

====SPIKE 1 CPU - 520-6936-xx====
Node 0 in the backbox.

Part numbers:
* 520-6936-00
* 520-6936-00A
* 520-6936-01
* 520-6936-10 (Video Out Support; Backward compatible with -00)
* 520-6936-10B
* 520-6936-11

====SPIKE 2 CPU - 509-1000-01 & 509-1003-01====
Node 0 in the backbox.

* 509-1000-01 was only used on the first two SPIKE 2 games (Batman 66 and Aerosmith).
* 509-1003-01 was used in all subsequent SPIKE 2 games to date.

This CPU came in two variations: a 50Hz version for European games, and a 60Hz version for USA games. The European electrical grid runs on 50Hz power, while the USA runs on 60Hz.

If bringing a game from one electrical region to another, two known methods to convert a game are to replace the CPU, or use an external voltage transformer with a frequency converter.

====Node Board - 520-7019-72A====

[[file:520-7019-72AFront.jpg|left|thumb|300px|Stern Node board from BM66 with Q5 blown and removed.]]
[[file:520-7019-72ABack.jpg|right|thumb|300px|]] 
This node board was used on at least BM66. 

====Node 10 Board - 520-5781-02====

The part that is most often damaged on this board is U1, a [https://www.mouser.com/ProductDetail/Trinamic/TMC5041-LA?qs=TiOZkKH1s2QUPp262HSTPw%3D%3D TMC5041-LA].

[[file:Node10.jpg|left|thumb|300px|Stern Node 10 board.]]
[[file:BlownSternNode10Board.jpg|right|thumb|300px|A blown Node 10 board with the typically blown TMC5041 shown.]] 

====520-5331-00D Grinder Board====
[[file:SPIKE520-5331-00DGrinder.jpg|left|thumb|300px|The "Grinder" board.]]
The "Grinder" board was used in at least AC/DC and Metallica (both S.A.M. games) to drive general illumination LEDs. Schematics for the board can be found in the Metallica manual (best) and the AC/DC manual.

It appears to be an "open loop" driver, with one way communication from the MPU/Driver to the Grinder board via the ethernet connector. The onboard microcontroller must be flashed with Stern proprietary code, making owner repair of this board problematic.

Although the schematics indicate use of an A8498 voltage regulator, that part does not appear on the actual board, nor do solder pads to accommodate the part.

{| class="wikitable"
!Part
!Function
!Locations (size)
!Availability
|-
|ATTiny4313-SU||microcontroller||U3 (SOIC-20)||not available as of 3/5/23
|-
|STP16CPC26TTR||LED driver||U2, U5, U6 (TSSOP24)||not available as of 3/5/23
|-
|A8498SLJTR-T||Voltage regulator||U7, not stuffed||not available as of 3/5/23
|-
|ZXMN7A11KTC||70V N-Channel 6.1A MOSFET||Q1-Q4||available as of 3/5/23
|-
|MAX232DR 11KTC||RS232 interface||U4 (SOIC-Narrow-16)||available as of 3/5/23
|-
|}
 

====Cabinet Node Board - 199-6967-00B====

[[file:SternSpike199-6967-00B.jpg|left|thumb|300px|Cabinet Node Board 199-6967-00B. Note that U14 on this board has been damaged.]] 

LED indicators on the board:
*Red: 48 volts is present at the board
*Yellow: Board is communicating with cpu board
*Green: 6 volts is present at the board

Ghostbusters # 520-6967-00 (replaced by 520-6967-72) Cabinet Node Board connectors:

*CN1: Universal Card link (if present on your particular board)
*CN2: Low tickets warning in ticket dispenser
*CN3: To Meter #1 (usually coin counter, use a 12 volt meter)
*CN4: To Meter #2 (usually tickets out, use a 12 volt meter)
*CN5: From Coin Door coin switches and coin entry LED lights
*CN6: Left cabinet switch inputs (tilt, start, etc)
*CN7: Right cabinet switch inputs
*CN8: From electronic coin mechanism (for export machines only)
*CN9: From Dollar Bill Acceptor
*CN10: From coin door volume and diagnostic switches
*CN11: Ticket dispenser
*CN12: Volume and diagnostic switches output to cpu board connector CN25
*CN13: RJ45 Node Data Bus
*CN14: 48 volts DC power input
*CN15: Optional spare LED +5 volt power source
*CN16: To shaker motor

====LED driver board - 520-8533-00A====
[[file:520-8533-00AComponentSide.jpg|left|thumb|300px|Cabinet Node Board 520-8533-00A. This board appears to drive LED lamps.]]
[[file:520-8533-00A.jpg|right|thumb|300px|Cabinet Node Board 520-8533-00A. This board appears to drive LED lamps.]]
 

====32-Light & Switch Board - 520-5322-xx====
There are two known board revisions: Revision E and revision H (notated on the board as 520-5322-00E or 520-5322-00H)

This board currently has 5 known designations based on the game code installed on it. Otherwise, the physical hardware appears to be the same. Note that installing a board in the wrong game will (at minimum) prevent it from working.

* 520-5322-00: Some documentation indicates when this was offered online purchase, it was in an unconfigured board with no code (thus did not work in certain games, such as Star Trek). Game manuals indicate this board originally came with WWE Wrestlemania Pro (SPIKE game), Star Trek Pro/Premium/LE (SAM games), KISS Pro/Premium/LE (SPIKE game)
* 520-5322-10: The Walking Dead Pro/Premium/LE (Note: SAM games)
* 520-5322-20: Star Trek Pro/Premium/LE (Note: SAM games)
* 520-5322-30: WWE Wrestlemania Pro, KISS Pro (and likely Premium/LE), Pabst Can Crusher, Primus (SPIKE games)
* 520-5322-72: Whoa Nelly, Pabst Can Crusher, Primus (SPIKE games)

====Spike 2 Dual Motor Control Board - 520-8414-00====
[[file:SternSpikeMotorControlBoard.jpg|right|thumb|300px|Spike 2 Dual Motor Drive Board, 520-8414-00. Note that this board has a blown L6206Q driver chip.]] 
This board appears on at least the following games:
*Elvira's House of Horrors
*Mandalorian
*Stranger Things (drives the ramp)
*Teenage Mutant Ninja Turtles
 

====Spike 2 Dual Motor Control Board - 520-5781-02====
[[file:Placeholder.jpg|left|thumb|300px|Spike 2 Dual Motor Drive Board, 520-5781-02.]] 
This board appears on at least the following games:
*Godzilla Premium and LE
*Rush Premium and LE
 

====Trough Serial Opto Receiver Extension Board====

Part numbers:
* 520-8516-00 (current version)
* 520-1051-00
* 520-7001-00
* 520-5345-00 (initial version)

===Dollar Bill Acceptors===

The Spike system machines come with a bill acceptor coin door and dollar bill acceptor wiring harness already installed. Many are wired for using 120 volts AC powered bill acceptors (Mars/MEI AE-2411-300 is recommended), but there are reports some machines are wired for 12 volts DC models instead. Here is a Ghostbusters which comes wired for 120 volts AC power for the bill acceptor.

[[File:Ghostbusters_bill_acceptor_connector.JPG|200px|thumb|left|Ghostbusters bill acceptor connector]] 

 

===Optional Equipment===

This power supply for 12 volt and 5 volt accessory items has four Molex output jacks and is fused:

[https://www.pinballlife.com/accessory-power-supply-for-stern-spike-spike-2-system-machines-backbox-mounting.html Power supply for backbox mounting]

This power supply is the same as above except it mounts in the lower cabinet near the cashbox:

[https://www.pinballlife.com/accessory-power-supply-for-stern-spike-spike-2-system-machines-cabinet-mounting.html Power supply for lower cabinet mounting]

This 8 way splitter provides eight 12 volt only Molex jacks and mounts only in the backbox:

[https://www.pinballlife.com/8-way-power-splitter-board-for-stern-pinball-machines-using-the-spike-spike-2-system.html 8 Way splitter for backbox mounting]

Knocker Kit provides a real knocker:

[https://www.pinballlife.com/real-knocker-kit-for-stern-spikespike-2.html Real Knocker Kit for Spike 1 and Spike 2]

===Linux OS===

Spike's central CPU node in the backbox runs Linux. The hardware is a derivative of the NXP i.MX6 [https://wandboard.org Wandboard].

The SD card has ext4 partitions, the most interesting being the root filesystem and /games. The rootfs contains a yocto build with no toolchain or kernel headers, but cross-compilation is possible using gcc-arm-linux-gnueabihf.

There is a serial console on connector CN2. This connector is generally not populated. It's also possible to configure the Ethernet port for remote access.

The game executable has a text-based interactive debug interface with some interesting options:
<nowiki> commands:
adj: perform operations on adjustments.
amp: amp system interface.
aud: perform operations on audits.
coil: fire a coil.
credit: manipulate credits.
debug: get debug information.
display: display system interface.
dsp: DSP interface.
knocker: perform operations on the knocker.
le: lamp effect system interface.
mode: interact with modes.
node: node diagnostics commands.
nv: get non-volatile ram info.
proc: get information about processes.
red: redemption interface.
replay: replay interface.
scene_cache: scene cache system interface.
score: manipulate player scores.
sound: sound system interface.
textsafe: show text safe region.
video_display: video display system interface.</nowiki>

Some more information can be found here:
* https://docs.missionpinball.org/en/latest/hardware/spike/connection.html
* https://pastebin.com/raw/RryUb8iC

==Problems and Solutions==
===Power Problems===

The main power supply is 48 volts @ 10.5 amps and has a cooling fan. Some versions have the fan on the front of the power supply while others may have the fan mounted on the top. Power supply is a Mean Well # RSP-500-48 (Jameco Electronics # 2198014).

 

[[File:48V_power_supply.JPG|200px|thumb|left|Ghostbusters Pro 48 volt power supply]] 

 

Ghostbusters wiring interconnection label.

[[File:Ghostbusters_interconnect.JPG|200px|thumb|left|Ghostbusters interconnection wiring label]] 

 

====Noisy Power Supply Fan====

There have been reports of the fan on the switching regulator 48 volt power supply becoming too loud. There is now a plug n play replacement fan kit. The fan in the kit is a lot quieter.

[https://pinside.com/pinball/market/shops/1170-pin-monk/02140-spike-quiet-fan-plug-n-play-kit Spike Quiet Fan Kit]

====Relocating the Power Switch====

One complaint with Spike machines is the fact the power on-off switch is located in the backbox. If the machine is located in a bank of machines, it may be difficult to reach the power switch. Some people have ordered a Stern # 515-7085-00 Power Switch and Bracket assembly and mounted it in the usual right front bottom cabinet location. Then wires are run up to the backbox and connected in place of the backbox power switch. Stern installs a shaker motor in the right front of the cabinet now. So the shaker motor (if installed) must be relocated farther back in the cabinet (about 6 inches) to the other side of the wooden divider.

[https://www.pinballlife.com/stern-onoff-rocker-switch-and-bracket-assembly.html Stern Power Switch and Mounting Bracket Assembly]

===MPU boot issues===

If the MPU doesn't boot, check that the memory card is firmly seated in its slot on the MPU board. Also, you can try re-seating the memory card. Sometimes this fixes Spike games that won't boot.

===Game resets===

Some reset/slam tilt problems have been traced to the shaker motor. Please check the service advisory bulletin.

[https://sternpinball.com/wp-content/uploads/2018/08/Stern-ShakerMotorAdvisory.pdf Shaker motor service advisory]

===Stern Insider Connected Displays Invalid Factory Config Message===
As of September 2022, [https://pinside.com/pinball/forum/topic/buyer-beware-replacement-spike-2-cpu-board-breaks-insider-connected it was discovered] that installing a new replacement Spike 2 MPU into a game causes the Stern Insider Connected feature to stop working and display the message when accessing the Insider Connected setup screen: "This machine has an invalid Factory Config. Contact your distributor."

To fix the problem, contact Stern support. The MPU will need to be shipped to Stern, where they will use proprietary software to program the board. Once the MPU is returned and installed, Stern Insider Connected should start functioning again.

===Solenoid problems===
===Lamp problems===
===Switch problems===
===Display problems===
Starting with Pirates of the Caribbean (a S.A.M. board set game), Stern replaced the normal Plasma Dot Matrix Display on European models with an LED variant because of the RoHS law. They first used PinLED DMDs, and later, switched to a red DMD specifically made for them (520-5052-05). The debate which looks better will be going on for your remaining lifetime and continue right into your next few lives.

====LED DMD bad vertical line====
[[File:Stern-LED-DMD-Bad.jpg|left|thumb|200px|Stern bad LED DMD]] 
If a game is always showing a semi-bright vertical line on the DMD, usually one of the LED segments is bad. Fortunately the bad segment can be found easily. As shown in the picture to the left, one pixel in the line is always dark. This 8x8 segment is the bad guy and needs to be replaced. The good thing is that this problem usually occurs with NIB games just after a few hours or days of game play so the DMD is still under warranty. If not, ask Stern for the availability of the LED segments. When replacing a block, be advised that the vias are small and are difficult to remove without the proper equipment.
 

===Sound problems===

The Spike 1 cpu board connector CN1 is the 2 channel backbox speaker output (two 4 ohm @ 10 watt 4 inch square speakers, use Stern # 031-5004-02). Connector CN4 is the lower cabinet woofer speaker output (one 8 ohm @ 20 watt 8 inch round speaker, use Stern # 031-5007-01). 

CN1 pinout:
*1: Black-White backbox right speaker -.
*2: Red-White backbox right speaker +.
*3: Key
*4: Black backbox left speaker -.
*5: Red backbox left speaker +.

CN4 pinout:
*1: Yellow-Black lower cabinet woofer speaker output -.
*2: Yellow-White lower cabinet woofer speaker output +.

CN18 (TRS headphone 3.5mm jack) pinout:
*TIP: headphone left, 8 ohm, 200mw maximum output
*RING: headphone right, 8 ohm, 200mw maximum output
*SLEEVE: Audio ground

CN27 Preamp (line) output to feed sound to an external monaural amplifier or subwoofer amplifier:
*1: Line out +, 600 ohms
*2: Line out ground
*3: Line out -, 600 ohms

 

The latest game codes now have speaker impedance settings for whether 4 ohm or 8 ohm speakers are installed in the machine.
Added UTIL->VOL adjustments, Speaker Balance, backbox speaker type, and cabinet speaker type for Spike 1 and 2 games.

===Flipper problems===
See [[Common Flipper Troubleshooting]] for general flipper information.

[[File:Ghostbusters_flipper_assembly.JPG|200px|thumb|left|Flipper assembly on Ghostbusters]] 

 

===Pop bumper problems===

[[File:Ghostbusters_pop_bumpers.JPG|200px|thumb|left|Ghostbusters pop bumper assemblies]]

 

===Opto problems===

===Shaker Motor Problems===

The shaker motor connects to connector CN16 (CN2 on early boards) on the cabinet node board located next to the plumb bob tilt. It will be labeled Shaker Motor. 
The pinout of CN16 is this:
*1: Shaker motor - (Blue wire)
*2: Shaker motor - (optional extra connection)
*3: Shaker motor + (optional extra connection)
*4: Key
*5: Shaker motor + (Red wire)

Genuine Stern SPIKE Shaker motor causes mysterious slam tilts during game:

[https://sternpinball.com/wp-content/uploads/2018/08/Stern-ShakerMotorAdvisory.pdf Service Advisory 2018]

If your shaker motor is damaged or worn out, you can purchase just the motor itself if desired.

[https://www.pinballlife.com/replacement-motor-for-stern-shaker-kits.html Replacement Spike/Sam shaker motor only]

====Third Party Shaker Motors====
All current SPIKE™ games allow for a shaker motor, but it should be a SPIKE shaker motor, not a SAM-system shaker motor (SAM is the previous system). After the initial launch of SPIKE™ games, it was discovered that motors from third-party manufacturers (in particular Pinball Life) had a capacitor that caused problems, and will blow out the node board.
[https://sternpinball.com/wp-content/uploads/2018/10/Stern-SB184.pdf Service Bulletin 184] advises against using third-party shaker motors entirely. Installation will void the game's warranty.

The symptom of this problem is that the Start button, plumb bob, and coin door GI lamps won't work; that is, the game becomes unplayable.

Some owners have reported that removing the capacitor from the third-party motor will fix the problem. Stern's public position is that owners should spend the extra money and buy an OEM motor. Many vendors do not clearly differentiate between an OEM part and a third-party part.

[https://www.pinballlife.com/stern-factory-authorized-shaker-motor-kit-for-stern-spike-spike-2-system-games.html Genuine Stern Spike shaker motor kit]

[https://www.pinballlife.com/shaker-motor-kit-rev-c-for-stern-spike-spike-2-system-games.html Third party Spike shaker motor kit]

All SPIKE system games already have the holes for a shaker motor pre-drilled and 10-32 T-Nuts already installed for mounting the shaker motor to the right of the cashbox.

===Missing Playfield Slide Brackets on Pro Models===

Starting with the Pro model of WWE, Stern removed the playfield slide brackets and replaced them with a couple of cheap pieces of threaded rod covered in heat shrink tubing and a ball shooter tip. This was so you could pull the playfield toward you a bit and rest those "pegs" on the lockdown receiver to service under the playfield. That didn't work very well if you needed to get to something at the very back of the playfield. Pinball Life has reproduced the playfield slide brackets as a set. Once installed, the playfield can be pulled out a lot farther to make it easier to work at the rear of the playfield. Premium and LE models already have the playfield slide brackets installed.

[https://www.pinballlife.com/stern-pinball-support-slide-bracket-kit-for-spike-spike-2-machines.html Spike cabinet playfield slide bracket kit]

Note: It now appears, starting with Iron Maiden, that Stern has gone back to installing the metal slide brackets on the bottom of the playfields on Pro models.

==References==

==Game Specific Problems and Fixes==

'''Ghostbusters Premium and LE models''' damaged Ecto Goggles LCD screen. Air balls flying up and hitting/damaging the LCD screen on the Ecto Goggles unit. Stern issued a service bulletin about this problem and came up with a metal shield to install on the machine to prevent this from happening.

[https://sternpinball.com/wp-content/uploads/2018/10/Stern-SB187-1.pdf Ecto Goggles Shield Kit Service Bulletin]

Other Than Pinball Games

2022-12-18T19:15:08Z

Jimpal: /* MPU= */

= Taito Ice Cold Beer =

== PinSide ICB Owners Thread ==
A very lengthy thread regarding the Taito ICB model can be found [https://pinside.com/pinball/forum/topic/ice-cold-beer-icb-owners-thread here].

== Florescent Lamp ==
The original playfield lamp is an F15T12. The fluorescent light degrades the paint on the backglass.
The florescent tube can be replaced with a modern LED, such as TBD.

== DIP Switch Settings==
[[File:ICBDIPSwitchSettings.jpg|400px|thumb|left| This image from the ICB manual, was also stapled to the inside of the rear door.]]
 

==MPU==
[[File:ICBMPUFront.jpg |400px|thumb|left|PCB Component Side]]
[[File:ICBMPUBack.jpg |400px|thumb|right|PCB Solder Side]]
 

== Taito Service Tips==
The following service tips were issued by Taito, and cover...
*Weak errant ball solenoid
*Ball sticks between hole and bar in attract mode (ROM revision)
*Lubrication of side rods
*Ramifications of stuck switch in the switch matrix

[[File:ROM_Version_Service_Bulletin_Page_1.jpg|400px|thumb|left|Weak errant ball solenoid ]]
[[File:ROM_Version_Service_Bulletin_Page_2.jpg|400px|thumb|right|Ball sticks between hole and bar in attract mode (ROM revision) ]]
[[File:ROM_Version_Service_Bulletin_Page_3.jpg|400px|thumb|left|Lubrication of side rods]]
[[File:ROM_Version_Service_Bulletin_Page_4.jpg|400px|thumb|right|Ramifications of stuck switch in the switch matrix ]]
 

==Diagnostics==
[[File:YT.png]] A video demonstrating MPU diagnostics can be found [https://youtu.be/XJtzrMd16wM here].

== Connector Pin-out ==

== Motor Replacement ==

Replacement motors for Ice Cold Beer were available from Twisty Arcade a few years ago. The installation procedure for this motor, or an equivalent can be found below. The principle part of the job is to transfer the gear from the old motor shaft to the new motor shaft, and modify the motor bracket to mate to the new motor.

The motor from Twisty Arcade came with a 6.2ohm, 5W resistor. It may be necessary to replace this part with a 10ohm, 5W resistor to slow the motor a bit more. If your game raises the bar too far to "serve" the ball, install a replacement resistor of perhaps 8.2ohm, 5W, or even the 10ohm part.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Taito Ice Cold Beer Replacement Motor Installation">
File:ICBReplacementMotorToInstall.jpg|<center>The replacement motor to be installed. The motor comes with an inline current limiting resistor (6.2ohm, 5W) to slow the new motor speed to close to the original motor speed.</center>
File:ICBOEMMotorBracket.jpg|<center>The OEM bracket, showing 4 motor attach points.</center>
File:ICBOEMMotor.jpg|<center>The OEM Motor, showing the gear to be transferred to the new motor.</center>
File:ICBHackMotorShaft.jpg|<center>Use a hack saw to cut the shaft off the original motor.</center>
File:ICBPunchGear.jpg|<center>Position the shaft/gear in a vise but don't tighten the vise on the shaft. Punch out the old shaft.</center>
File:ICBInstallGear.jpg|<center>With the "tail" of the new motor shaft on a solid surface, gently tap the original gear onto the new motor shaft.</center>
File:ICBNewGearInstalled.jpg|<center>The original gear, installed on the new motor shaft. Note that the shaft doesn't quite come to the gear edge, so that it mates correctly when installed into the gearbox.</center>
File:ICBBracketMod.jpg|<center>Enlarge the hole in the original bracket to 13mm. Here a 1/2" bit in a drill press (clamp the part down before drilling) is used to remove most of the material...</center>
File:ICBHoleEnlarge.jpg|<center>...and then a rat tail file is used to complete the enlargement.</center>
File:ICBModifiedBracketInstalled.jpg|<center>The original bracket, deburred, and installed on the new motor. Two screws are sufficient to hold the motor in place.</center>
File:ICBReplacementMotorGearInstalledView.jpg|<center>A view of the new motor and original gear, perfectly aligned with the motor gearbox.</center>
File:INewMotor.jpg|<center>The new motor, in place, ready to go.</center>
</gallery>
</center>

Stern S.A.M. System Repair

2022-09-21T23:56:36Z

Jimpal: /* Grinder Board */

{{WIP}}

Click to go back to the [[Data_East/Sega/Stern_Pinball_Repair_Guides | Data East/Sega/Stern pinball repair guides index]].

==Introduction==
The first full production game to use the S.A.M. Board Set was World Poker Tour in 2006. The last production game was The Walking Dead (Limited Edition) in 2014. One of the features of the S.A.M. board set is that the software can be updated with a USB stick.

S.A.M., as an abbreviation, has never been officially explained—but Sam Stern was Gary Stern's father, and formerly ran Williams and Stern Electronics.

==Games==

{| class="wikitable sortable"
!Title
!Date of Release
!Model #
!Versions
!Notes
|-

|[[World Poker Tour]]|| 2006 || I-0088 || Pro ||
|-
|[[Stern Simpsons Kooky Carnival|The Simpsons Kooky Carnival (Redemption Game)]]|| || || Redemption ||
|-
|[[Pirates of the Caribbean]]|| 2006 || I-0092 || Pro ||
|-
|[[Family Guy]]|| 2007 || I-0093 || Pro ||
|-
|[[Spider Man (Stern)]]|| 2007 || I-0094 || Pro, Black-Suited ||
|-
|[[Wheel of Fortune]]|| 2007 || I-0098 || Pro ||
|-
|[[Shrek]]|| 2008 || I-00A5 || Pro ||
|-
| [[Indiana Jones 4]] || 2008 || I-00A4 || Pro ||
|-
| [[Batman (Stern)]] || 2008 || || Pro, "Standard" || The "standard" model was a low production run test of a stripped down version of the game targeted at the home market.
|-
| [[CSI: Crime Scene Investigation]] || 2008 || I-00A2 || Pro ||
|-
| [[24]] || 2009 || || Pro ||
|-
| [[NBA]] || 2009 || || Pro ||
|-
| [[Big Buck Hunter Pro]] || 2010 || || Pro ||
|-
| [[Iron Man]] || 2010 || || Pro, Classic || The "classic" model was a stripped down version aimed at the home market.
|-
| [[Avatar]] || 2010 || || Pro, Limited Edition ||
|-
| [[The Rolling Stones (Stern)]] || 2011 || || Pro, Limited Edition ||
|-
| [[Tron]] || 2011 || I-00B9 || Pro, Limited Edition ||
|-
| [[Transformers]] || 2011 || I-00C3 || Pro, Limited Edition || The limited edition games featured 3 variations, Autobot, Decepticon, and the "combo" edition.
|-
| [[AC/DC]] || 2012 || || Pro, Premium, Limited Edition || The limited edition included variations based on different AC/DC albums.
|-
| [[X-Men]] || 2012 || I-00D1 || Pro, Limited Edition || The limited edition included 2 variations, the Wolverine and Magneto editions.
|-
| [[Avengers]] || 2013 || || Pro, Premium, Limited Edition || The limited edition included 2 variations, the regular and Hulk editions.
|-
| [[Metallica]] || 2013 || I-00E1 || Pro, Premium, Limited Edition ||
|-
| [[Star Trek (Stern)]] || 2013 || I-00E4 || Pro, Premium, Limited Edition, Vault ||
|-
| [[Mustang (Stern)]] || 2014 || I-00F1 || Pro, Premium, Limited Edition ||
|-
| [[The Walking Dead]] || 2014 || I-00F5 || Pro, Limited Edition ||
|-
|}

==Technical Info==
===The S.A.M. Board Set===
[[File:Stern SAM Boardset.JPG||left||thumb||300px||Stern SAM Boardset (from Tron LE)]] 
The S.A.M. System board set consists of three boards in the back box. The CPU / Sound board, I/O Power Driver board, and the Display Power supply. Later SAM games, which use LED dot matrix displays (versus high voltage plasma displays) do not employ the display power supply. Later SAM games which use LEDs in place of incandescent bulbs for all playfield lighting, add an additional board to power the LEDs, and on LE games, a board to control these LEDs.

The basic S.A.M. board set is a miniaturized version of the Whitestar board architecture. The board set is dimensionally reduced and manufactured with some surface mount components. The logic functionality is easily traceable back to the Whitestar board set.
 
====SAM CPU/Sound Board====
<center>
<gallery widths=400px heights=300px perrow=2 caption="The various generations of the Stern SAM CPU board">
File:SAMRevG.jpg|<center>Stern first generation CPU/Sound Board 520-5246-00 Revision G. Note Jumpers which were incorporated into the PCB with Revision H</center>
File:SAMRevGBack.jpg|<center>Stern first generation CPU/Sound Board 520-5246-00 Revision G, back side. Note the jumper</center>
File:SternSAMCPU.jpg|<center>Stern first generation CPU/Sound Board 520-5246-00 Revision H (up to Tron). The adaptor is not part of the CPU. It's used in the White Star test fixture.</center>
File:Stern 520-5303-03 LE CPU.JPG|<center>Stern first generation CPU/Sound Board 520-5303-03 Revision H. This board is identical to 520-5246-00 but factory programmed differently to run the Limited Edition Code (here Tron LE). </center>
File:SternSAMCPU-520-5337-00.jpg|<center>Stern second generation SAM CPU/Sound Board 520-5246-02 (Transformers and forward). The USB controller chip on this board changed to an FTDI VNC2-48L1B - Vinculum-II Programmable USB 2.0 Host. This is the AC/DC version of the board with 2 64 MBit flash roms 520-5337-01 (Pro) 520-5337-00 (Premium/LE).</center>
File:SternSAMCPU-StarTrekPro.jpg|<center>Another Stern second generation SAM CPU/Sound Board 520-5352-00 (Star Trek Pro) 520-5352-01 (Star Trek Premium). To make life for operators, repairmen and collectors easier Stern released another version of this CPU with Star Trek Pro/LE. It is identical to 520-5337-00/-01 but only has one 64 MB flashrom. If you need to buy a replacement make sure you get the right version. They are not interchangable. Same goes for the bootrom.</center>

</gallery>
</center>

Up until now there are five versions of the SAM CPU/Sound board. The first version had several minor revisions over its lifetime, but they can all be used in all games up to Tron. The first revision of this board used in World Poker Tour has some problems with USB 2.0 sticks. If you own this game, see that you can find an old 32MB stick. They usually work fine. Second one has some hardware modifications in the circuit for the Atmel AT43USB380 chip.
Starting with Transformers the USB controller became unavailable and was replaced with a different chip on the CPU. Number changed to 520-5246-02 and that makes three. All these boards use a 32 MB flash rom. With AC/DC space was running out and two 64 MB flash roms are used. To save a few bucks, Star Trek Pro and LE are fitted with only one 64 MB flash rom adding another variant to the pot.

The LE and Premium models use a variation of the Pro board. The programmed chips on them are different and so they are not interchangeable. Trying to use Premium software on the Pro or vice versa is not possible. A hardware mismatch error message will be shown. For a complete list of games up to X-MEN with their board numbers see [https://sternpinball.com/wp-content/uploads/2018/10/sb178.pdf Service Bulletin #178].

Games after X-MEN use the following boards:
{| class="wikitable" style="margin: 1em auto 1em auto; text-align:center;"
!Game Name
!CPU Bd. No.
!I/O PWR DRV Bd. No.
!6-Trans. DRV Bd. No.
!LED Bd. No.
!U9 Pinball Boot ROM
!Remark
|-
|Avengers Pro||520-5246-02||520-5249-00|| || ||V2.0||
|-
|Avengers Premium and LE||520-5303-04||520-5317-00|| || ||V2.0||
|-
|Metallica Pro||520-5337-01||520-5249-00 || || ||128MB V1.0||same as AC/DC just has an updated bootrom
|-
|Metallica Premium and LE||520-5337-00||520-5317-00|| || ||128MB V1.0||same as AC/DC just has an updated bootrom
|-
|Star Trek Pro||520-5352-00||520-5249-00 (Rev. D)||520-5326-01||none||64MB V1.0||
|-
|Star Trek Premium and LE||520-5352-01||520-5317-00 ||t.b.d.|| ||64MB V1.0||
|-
|Mustang Pro||520-5352-00||520-5249-00 (Rev. D)||none||520-6822-00||64MB V1.0||
|-
|Mustang Premium and LE||520-5352-01||520-5249-00 (Rev. D) ||t.b.d.||t.b.d.||64MB V1.0||
|-
|The Walking Dead Pro||520-5337-01||520-5249-00 (Rev. D)||t.b.d.||t.b.d.||128MB V1.0||
|-
|The Walking Dead Premium and LE||520-5337-00||520-5249-00 (Rev. D)||t.b.d.||t.b.d.||128MB V1.0||
|}
 

[[File:SAMRegionSpecificGuard.jpg|left|thumb|300px|Message displayed when US/European boards are mismatched.]] 
To make things worse, the boards for 50 Hz countries are programmed differently to prevent cheaper direct imports from the US. This doubles all of the board variants. Thank you Stern. NOT!

An attempt to use mismatched 50/60Hz boards will yield the message shown at left.
 

S.A.M. is now at the end of its life. A completely new system named [[Stern SPIKE™ System Repair|SPIKE™]] has been developed based on an earlier revision of it being used in the Stern home model pinball machines referred to as "The Pin". This new platform is first used in the Stern WWE Wrestlemania pinball machine.
 
=====SAM CPU/Sound Board Connectors=====
[[File:SAMCPUPinOut.jpg|left|thumb|600px|The S.A.M. CPU/Sound Board Connector Specification.]] 
 

====SAM I/O Power Driver Board====
[[File:SternSAMDriver.jpg|left|thumb|300px|Stern SAM Powerdriver 520-5249-00 Revision A]] 
520-5249-00 Revision A 
Power, fuses, bridge rectifiers. GI relay, coil and flasher drivers. 

The adapter in the pic on the left is not part of the board and only used on the Stern White Star test fixture. 
 

[[File:520-5249-00_Rev_D.jpg|left|thumb|300px|Stern SAM Driver Board 520-5249-00 Revision D]] 
520-5249-00 Revision D 
This version uses the surface mount [https://www.mouser.com/ProductDetail/STMicroelectronics/VND5160JTR-E?qs=F%2FnHc52k2u8GgcT2y8z41Q%3D%3D VND5160J] driver in place of the VN02N solid state relay. The VND5160J are located at U10, 12, 14, and 16 near J13 on the left side of the driver board. This board was used in Iron Man Vault Edition and other SAM games with LED controlled insert lamps (see above table in the CPU/Sound board section).
 

[[File:SternSAMDriverBoard.jpg|left|thumb|300px|Stern SAM 520-5317-00 Driver Board]]
[[File:SAMXilinxLampMatrix.jpg|right|thumb|300px|The Revised Lamp Matrix Section of the Stern SAM 520-5317-00 Driver Board]] 
Starting with the LE and Premium edition games Stern now uses a new driver board. The lamp section in the lower left corner of the board has been replaced with a programmable Xilinx CPLD controlling the LED lamp boards (see image at right). As Stern (and Sega before Stern) has done for previous PALs and CPLDs, a color coded paint dot on the device indicates the software revision level that it has been programmed with.

Since these games used LEDs exclusively, 18VDC is no longer needed and as such, that power circuit has been removed from the board.

The 5V section has been completely overhauled, replacing the previously used LM317 and it's large heat sink with a small, integrated DC-to-DC converter, part number APXW005A0X3-SRZ. About 13VAC is rectified by BRDG4 and smoothed with two 15,000uf/25V filter caps connected in parallel. The resulting 21VDC is presented to the DC-to-DC converter which regulates it down to 5VDC.

[[File:DS1832.jpg|left|thumb|300px|The 3.3V device, a DS1832, shown in-situ. Note that this SOP-8 form factor chip does not have the traditional "pin 1" marking.]] 
A DS1832 3.3V Voltage Watchdog and Reset Generator is used on this board, as shown at left.
 

=====SAM I/O Power Driver Board Connectors=====
[[File:SAMDriverPinOut.jpg|left|thumb|600px|The S.A.M. I/O Power Driver Board Connector Specification.]] 
Note that this board pinout is valid for driver boards made prior to the change to the lamp matrix drive circuit.
 

====Display Power Supply====
[[File:Stern WS DMD PSU.JPG|left|thumb|300px|Stern 520-5138-00 Display Power Supply]]
SAM games equipped with high voltage gas plasma dot matrix displays use the same 520-5138-00 Display Power Supply as the Sega/Stern White Star games. These high voltage power supplies are pretty beefy but often become quite toasty, making the traces very fragile to repair.
 

====128 x 32 Dot Matrix Display====
Because of the RoHS law, European models from POTC to Family Guy use a modified PinLED DMD. Later games use a 520-5052-05 Red LED DMD. Starting with Transformers, Stern games use a low voltage LED 128 x 32 dot matrix display (part # 520-5052-15). It's different from the -05 variant. It uses brighter Orange/Red LED segments and different TTL chips. The LED dot matrix displays are comprised of 64 discrete 8x8 LED matrix displays.

All US Stern games before AC/DC use a 128 x 32 "standard" plasma dot matrix display (part # 520-5052-00). With AC/DC, Stern also started to use LED DMDs in US models, completing the phase-out of plasma displays in their games.
<center>
<gallery widths=500px heights=180px perrow=2 caption="Stern Red 520-5052-05 5VDC LED DMD">
File:SternRedLED-DMD.jpg
File:Stern-520-5052-05-Back.jpg
</gallery>
</center>
<center>
<gallery widths=300px heights=300px perrow=2>
File:SternRedLEDBlocks.jpg |<center>Close up of the 8x8 LED blocks used on the LED DMD</center>
File:SternRedLED-DMDColumnDriver.jpg ‎|<center>Close up of SSOP 24 pin column drive IC. TI Part number TLC5926IDBQR is a valid sub</center>
</gallery>
</center>
 

====Other Stern PCBs====
=====Grinder Board 520-5331-00=====
[[File:SternGrinderBoard.jpg||left||thumb||300px||Stern 520-5331-00 Grinder Board]] 
The "Grinder" board acts as a distribution and control center for various strings of LEDs on the playfield. It was probably introduced with the SPIKE game system but also is used in some "vault" games as this one was in an AC/DC Premium vault edition game with a 2018 production date.
 

===Recommended Documentation===
As always, it is highly recommended to possess a game manual. Every game manual is full of detailed information regarding game specific switch, lamp, and coil assignments. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended [http://pinwiki.com/wiki/index.php?title=Pinball_Parts_Suppliers pinball parts suppliers]. 

Since Avatar Pro Stern no longer includes printed manuals with it's Pro models. You usually get a few sheets of junk they call documentation but it's insufficient if you need to repair your game. The yellow section is mostly absent and schematics for newer boards are not included or useless photocopies (see AC/DC LE pdf files). Good luck if you have a problem here. You can only hope this changes again because the Pro modells are targeted to operators. 

As of April 2014, The Stern website no longer archives PDF S.A.M. schematics. However, individual game manuals are available on their respective game pages. A game index can be found in the right margin on the "buy" page [http://sternpinball.com/buy here].
 

Stern Pinball makes Technical Service Bulletins available on their website [http://sternpinball.com/service-bulletins here].
 

===USB Code Update===
''Note: this information can be found on the front inside cover of S.A.M. System Game Manuals.'' 

Step 1) Open the Back Box 
Step 2) On the CPU/Sound board set Dip Switch #8 to "ON". 
Step 3) Press the white Reset Button (S1 RESET) or power cycle the game. 
Step 4) The DMD should show the current software version installed. Press the "SELECT" button on the inside of the coin door to continue. 
Step 5) Highlight the "UPDT" icon on the display and press "SELECT". 
Step 6) The game will prompt you to insert the USB Memory Stick. 
Step 7) Pick the correct file on the USB drive and press the "SELECT" Button. 
Step 8) Follow the directions on the display.

Warning: If you live in a country with a power line frequency of 50Hz, like any country in Europe, do not update your game code when turning the game on for the '''first time ever'''. As of 06/29/2012, there is a bug in either the system code or the update code. Doing so will usually wipe out the country lock code from the game. The CPU will need to be exchanged. See '''[https://sternpinball.com/wp-content/uploads/2018/10/sb170.pdf Stern Service bulletin 170]'''. Let the game remain in attract mode a few minutes or play a few games with the old software first. This has been observed with a Batman Dark Knight and ACDC/LE.

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:Stern SAM Coin Door Buttons.JPG|200px|thumb|left|SAM coin door buttons]]
[[File:Stern SAM HP Switch.JPG|160px|thumb|right|20v / 50v Interlock Kill Switch]] 

With the switch to the SAM system, Stern added a fourth switch to the coin door diagnostics switch bank. For people who are accustomed to entering diagnostics on Williams WPC games, this four button set up will feel much more natural.

Located just inside the coin door on the hinge side is an interlock style "kill" switch. This kill switch is used to kill all power to the solenoids, when the coin door is opened. Since it is an interlock style switch, it can either be depressed (when the coin door is closed), or it can be extended outward to turn the switch on. To extend the switch to the on position when the coin door is open, grasp the switch, and gently pull it out to the lock position.

This kill switch is a double pole switch. Wiring to one pole of the kill switch is BLK-YEL and BLK-YEL, while the other is RED-WHT to WHT-RED—yes, the colors do not match!
 

===The New Stern LED Lamp System===
Stern developed a new serial lamp control system for the release of Tron Limited Edition. This system uses a serial protocol to control playfield LEDs. 

There are three components to the system
*the serial bus, which carries clock, data, power and strobe signals
*lamp boards, typically strips, which carry a serial LED controller for on-board LEDs and satellite LEDs
*LED satellite boards, which solder to the lamp boards.

The lamp boards daisy chain. Therefore, the controller can feed, say, 8 bytes of serial data to the lamp boards and strobe the data in, turning on or off 64 LEDs. This system is potentially expandable to hundreds of controlled lamps, breaking the constraints of the traditional lamp matrix. The lamp boards and LED boards can be assembled outside the game,simplifying the production and assembly of the wiring harness. 

The controller used is an STP16DPS05. This device controls 16 LEDs, and uses a constant current output. Therefore, it needs no current limiting series resistors, although Stern has implemented series resistors on the satellite boards. [any ideas here?] The driver is also capable of reporting short and open LEDs, but it is unknown if Stern has implemented this feature. 

In terms of diagnosis, one failed board could disable the entire system. The STP16DPS05 is a likely candidate for failure if an LED satellite board tangles with GI or other voltages. Replacing the chip is tricky as it has a full-contact heat transfer pad on the underside, which is difficult to heat properly without hot air or IR equipment. 

It may also be useful to have a z-connector on hand to jump around a failed board. This will result in incorrect light patterns, but will at least demonstrate that the system is driving the daisy chain. 

===Optional Accessories===
====Knocker====
The "token dispenser" option transistor can still be used to drive a knocker, and the body of the game still has a connector for the signal.
A step-up circuit is required because Q24 is a low-voltage output. 520-5254-00 does a good job, but it means finding connections for solenoid ground, solenoid +50V, and solenoid +20V (if your board is the newer revision, which the new ones are).

On the new-style mostly-metal heads (Star Trek and later) there is no good place to add the knocker in the head anymore.

See also [[Sega/Stern_White_Star_Repair#Adding_a_Real_Knocker_to_White_Star_Games]]; directions are similar, but not quite identical.

====Slam Switch====
Most SAM games support an optional slam tilt switch, a feature missing
on most Stern/Sega games back into the Whitestar era. The slam switch
guards against abuse, but it also provides a convenient way to reset the
game on ball 1 when it's not going so well.

On early SAM games, an optional switch can easily be installed to
add the slam tilt feature. Part is 502-5032-00,
available from parts suppliers including [http://www.marcospecialties.com/pinball-parts/502-5032-00 Marco].
This installs neatly into the coin door with the center gusset surrounding
the sticker with the game's name.

On later coin doors (the center gusset is gone, and the dollar bill validator
blank is larger) there is no place to mount the switch, but the
harness still has the optional slam connector. If adding a slam switch is
still desirable,
[https://na.suzohapp.com/products/pinball_parts/95-4176-00 Suzo-Happ part 95-4176-00]
can be used. This mounts over the lock. A connector will still need to be added
to go into the existing harness, but no diode is required.

====Tournament button====
Early games (like WPT) have a tournament button on the lockdown bar.
This may not be useful in home use, but it can be annoying to connect
and disconnect when opening the lockdown bar. The entire "guts" of the
button can be removed instead, keeping the button on the lockdown bar
but making it nonfunctional, and making it easier to open the lockdown bar. Alternatively, Cliffy sells a kit for remounting the button in the dollar bill validator hole on the coin door.

Later games have the tournament button embedded into the cabinet below the
start button.

Early games have a 5-pin .062 Molex connector in the coin door wiring harness for adding the button. A kit is available from the usual suspects that wires up to the hole on the lockdown bar. [http://www.marcospecialties.com/pinball-parts/500-6587-06-TK Marco lists this kit as 500-6587-06-TK.]

Later games have a bunch of QD wires in the wiring harness, but they don't go through a single connector anymore. In this case, only the button is required. [http://www.pinballlife.com/index.php?p=product&id=3214 Pinball Life lists this part under a similar part number.] The connectors are in the wiring harness leading to the coin door and can be pretty well hidden.

The switch between these two is (maybe? probably?) when the tournament button moved from the lockdown bar to the front of the cabinet. (Wheel of Fortune may be the game where this changed?)

====Shaker Motor Kit====

On many (but not all) S.A.M games, a shaker motor can be added by using either a genuine Stern shaker motor kit or a third party shaker motor kit. Some games have a factory-installed harness for the shaker, saving the trouble of installing one included with the kit.

[https://www.pinballlife.com/stern-factory-authorized-shaker-motor-kit-rev-b-for-most-stern-sam-system-games.html Genuine Stern shaker motor kit] This includes the wiring harness.

[https://www.pinballlife.com/shaker-motor-kit-rev-b-for-most-stern-sam-system-games.html Third party Shaker Motor Kit] This does not indicate that it includes the wiring harness.

If you have a machine with a damaged or worn out shaker motor, you can purchase just the "motor only" to repair your machine's shaker motor.

[https://www.pinballlife.com/replacement-motor-for-stern-shaker-kits.html Replacement Shaker Motor Only]

====Playfield Slide Brackets Kit====

Some PRO models did not come with playfield slide brackets. Without them, it is difficult to service things at the rear of the playfield. Pinball Life has reproduced these brackets as a set. Once installed, it's much easier to service things at the rear of the playfield.

[https://www.pinballlife.com/stern-playfield-support-slide-bracket-kit-for-sam-machines.html SAM cabinet Playfield Slide Brackets Kit]

==Problems and Solutions==
===Game is Completely Dead===
If the game does absolutely nothing when the power switch is turned on, first check the primary 8A slo-blo fuse (domestic games) located at the power box in the front right of the machine. If the fuse is mildly blown, replace the fuse, and see if the game turns on now. If the fuse is violently blown, remove the 4 screws which secure the power box to the cabinet, and flip it over. See if the varistor has blown. A tell tale sign of the varistor blown are black scorching on the inside of the box in the vicinity of the varistor. Replace the varistor with a 130V version.

<center>
<gallery widths=300px heights=220px perrow=4 caption="Stern SAM Power Box and Replacement of Varistor">
File:Stern SAM Power Box.jpg|<center>Stern SAM Power Box</center>
File:Stern SAM Varistor Aftermath.jpg|<center>Tell tale sign that the varistor had blown. This was due to a lightning strike.</center>
File:Stern SAM New Varistor.jpg|<center>Replacement 130V varistor installed</center>
File:Stern SAM Varistor Fuse.jpg|<center>Blown primary fuse and varistor</center>
</gallery>
</center>
 

===S.A.M. Fuse Table===
[[File:SAMFuseTable.jpg‎|200px|thumb|left|Fuse table listing for S.A.M. games]] 
All S.A.M. games use fuses as enumerated at left. 

===5VDC Power Issue===

An issue of low 5VDC from the power/driver board that seems to happen somewhat frequently is caused by the lack of connection between the LM338K heat sink and ground. This is caused by the extra circular heat sink that is coated with black oxide and can isolate the screws and therefore the LM338K case from ground. The correction for this issue is simple. Remove the two screws. scratch the black oxide from the heat sink so that the screws can now "make" with the regulator case. Or, simply remove the extra heat sink.

===MPU boot issues===
====Game with CPU Rev F resets during game play====
This is mostly a problem with CPU boards from World Poker Tour. The first boards had a problem with the Flash ROM which caused random reboots or lockups during gameplay see [http://www.sternpinball.com/service-bulletins/service-bulletin-163-world-poker-tour Service Bulletin #163].

The service bulletin doesn't show which changes were made or which boards are affected. Unfortunately not all boards seem to have been modified at this point in time. A used game which has the old CPU in it can still be bought, either because the operator was lazy or swapped boards. Stern doesn't seem to be interested in fixing the problem free at charge after 8 years, and doesn't even respond to queries about it.

So if this problem is experienced, first check if the board is one of the affected boards. If the CPU is 520-5246-00 Rev. F, it's a likely candidate.

Next, check if it has already been modified. See if a thin green wire goes to the chip at location U44. This is the 29GL256N Flash ROM which holds the game code. There are usually two other green wires near the power connector J11 from an earlier factory hot fix which have nothing to do with this problem. They deal with RAM issues and all Rev. F boards should have them.

If the modification has not been made, try first to resolve the issue with the seller or Stern. If the issue cannot be resolved, continue below.

To modify the board, experience in SMT soldering of very fine pitch parts is needed. Also it's a $500 PCB, so if something goes awry don't blame PinWiki.

Two modifications are needed on the front and back of the board:

[[File:Stern-SAM-Rev-F-Back.jpg|left|thumb|200px|Modified Board Back Side]]
[[File:SAMRevGJumpersFront.jpg|right|thumb|200px|A revision G board with factory applied modifications - front]]
[[File:Stern-SAM-Rev-F-Front.jpg|left|thumb|200px|Modified Board Front Side]]
[[File:SAMRevGJumpersBack.jpg|right|thumb|200px|A revision G board with factory applied modifications - back]]

First, cut the trace at location 1 on the backside of the board. This is going to the OE# pin 34 of the 29GL256. It will need to be rewired to the NRD/NOE pin 49 of the U42 Xilinx CPLD. To do this run a wire between location 2 and 3. Check the work by measuring continuity between pin 41 of U13 and pin 34 of the Flash ROM.

Next comes the tricky part. CE# pin 32 needs to be rewired directly at the Flash ROM. Location 4 at the front picture. First cut the trace at this pin. It's the fourth counting from the right and is around 5mm long. It's connected to ground, so double check that it's open after cutting, or damage of U42 will likely occur. Then, run a wire from pin 32 to location 5 on the picture. This is the original trace previously running to pin 34. It's the chip select for the Flash ROM pin 71 GF0 coming from U42.

This modification properly connects the Flash ROM Output Enable and Chip Select pins. Something which Stern should have done in the first place. Also the schematics are wrong and don't show this. Revision G CPUs still had this and some other modifications done by the factory. Only with Revision H the pcb was changed and the schematics on Sterns website and in all manuals only show the revision G CPU. The barely readable Avengers LE schematics show the correct wiring for the Flash ROM despite being for the later SAM CPU with different USB.

While it runs stable afterwards there is unfortunately a problem with this modification. The Flash ROM can no longer be written to. Updates will fail. OE# needs to be held high during a write cycle and this doesn't happen. To remedy this, it is likely that U42 will have to be reprogrammed. The owner of the modified board here had the latest WPT update already flashed, and didn't want to risk bricking it so this has not been done yet.
 

====Game with CPU Rev F or G does not boot ====
As stated in an earlier section the Rev. F and G 520-5246-00 CPUs had the chip select inputs to the Flash ROM modified. If your game doesn't boot check if one of the two wires for the modification has come loose. This can happen because not enough solder and/or flux was used doing the connections. This can be verified by putting the game into update mode (setting dip switch 8 to ON). If the CPU boots here check the connection first.
 

==== 12V Not Detected, Check Fuses F12, F13 ====
[[File:SAMCheckF12F13.jpg|200px|thumb|left|Message displayed with loose LM338K voltage regulator nuts/screws.]] 
The message shown at left is sometimes the result of the two nuts holding the LM338K voltage regulator on the driver board becoming loose. Tightening those two nuts may correct the issue.
 

====Relocating the battery from the MPU board====
The Stern S.A.M. system uses a single 3v lithium CR2430 "button cell" for its memory backup. These cells have very long life and are not prone to electrolyte leakage so you do not need to do this.

If you really, really want to relocate the battery, use a 2 cell holder, with two AA batteries. No blocking diode is required.
 

==== Connecting a logic probe to the MPU ====
==== Using a PC Power Supply For Bench Testing ====

===Game resets===
===Solenoid problems===
===Lamp problems===
If you have a bulb not working, seat the wiring into the IDC type socket better. I've run into a lot of these where the wires aren't seated and making good electrical contact.

===Switch problems===
If a switch isn't working. The three most common things I've seen is. 1- crappy switch, even if new. 2- if wires go into a IDC connector nearby, be sure they are seated good and making electrical contact. 3- broken wire at switch, or inside casing or harness, easy to quick check continuity of wiring.

===Display problems===
====DMD LED to Plasma conversion====
Starting with Pirates of the Caribbean, Stern replaced the normal Plasma Dot Matrix Display on European models with an LED variant because of the RoHS law. They first used PinLED DMDs, and later, switched to a red DMD specifically made for them (520-5052-05). The debate which looks better will be going on for your remaining lifetime and continue right into your next few lives, but here, we show how to replace the LED DMD with a standard Plasma Dot Matrix Display.

The following parts are needed:

<ul>
<li>1 x 520-5138-00 Stern Display Power Supply Board
<li>1 x 036-5454-01 SAM DMD Display Cable
<li>1 x 535-9769-00 PCB Metal Mounting Plate (Display)
<li>1 x 830-6053-00 Plastic Cover Danger High Voltage
<li>2 x 254-5000-05 1-1/4" x 3/8 Plastic Spacer Grey
<li>2 x 237-5975-00 #8 x 3/8 SHWHSec (Zinc) Screw
<li>2 x 02-4425-2 Machine Post/Stud standard metall threaded posts with #8 bottom and #8 top (for the gray spacers).
<li>2 x #8-32 Nylon Insert Lock Nut
<li>4 x #6 x 1/2" Wood Screw to mount the unit in the backbox
</ul>

You can get all these parts from your favorite pinball dealer. I got them from Pinball Life. If they are not on the web page, ask.

You need to first assemble the High Voltage unit. Assembled it looks like this one here:
<center>
<gallery widths=300px heights=200px perrow=3 caption="Stern SAM High Voltage Unit">
File:STERN-SAM-HV1.jpg|<center>View 1</center>
File:STERN-SAM-HV2.jpg|<center>View 2</center>
File:STERN-SAM-HV3.jpg|<center>View 3</center>
</gallery>
</center>

Just screw it into the backbox of your Pinball over a ground strap:
[[File:Placeholder.jpg|left|thumb|200px|No picture yet]]
 
The cable which goes into the left side is somewere hidden in the wiring harness of your pinball:
[[File:Placeholder.jpg|left|thumb|200px|No picture yet]]
 
[[File:Stern-LED-Dmdcable.jpg|left|thumb|200px|]]
The LED DMD plugs into your wiring harness with a 2 pin connector. You need to remove the connector and connect the 5V line to you DMD HV unit. You should find the corresponding 2 pin plug which matches the one on the picture nearby. Warning: the wires should be red and black. At least in Family Guy and Shrek there is a similar connector with 2 brown or black wires with color stripes nearby. This one is for the optional knocker kit. Make sure you do not connect this one to your DMD 5V line. Doing so will take out the DMD and the SAM CPU beyond repair! If unsure measure the voltage on this connector first.
 
 
If your game uses a PinLED LED DMD, a small PCB is connected to connector J5 on the SAM CPU. Take this one out and install the ribbon cable directly in J5 on the SAM CPU. Now you just need to replace the DMD with a standard plasma DMD and, voila!, it should work.
 

====LED DMD Entire Column Lit Constantly====
[[File:Stern-LED-DMD-Bad.jpg|left|thumb|300px|A Failed LED block on Stern 5VDC LED Display.]]
[[File:SternDisplayPixelColumnOut.jpg|right|thumb|300px|Another example of a failed LED block. Image courtesy of PinSider Kawydud.]]
[[File:SternRedLED-DMDColumnDriver.jpg ‎|left|thumb|300px|Another example of a failed LED block. Image courtesy of PinSider Kawydud.]] 
If a game is always showing a semi-bright column on the DMD, one of the LED blocks has failed. Fortunately, the failed block is still fairly easy to obtain. As shown at left, one pixel in the column is dark. The 8x8, 1.9mm LED block that contains this "pixel" should be replaced. Stern can supply replacement blocks. As of April, 2021, they could also be obtained from Marco Specialties and perhaps other sellers.

When replacing a block, be advised that the vias are quite small. The blocks are difficult to remove without the proper equipment and expertise.
 

===Sound problems===

====No Sound====
[[File:PCM1755DBQ.jpg ‎|left|thumb|300px|The PCM1755DBQ D-to-A Converter. Pin 1 is lower, right.]] 
A problem which has been seen in both first and second generation S.A.M. boards is a complete loss of sound in an otherwise completely working system. Reflashing the system will not correct the issue. Even though all voltage indication LEDs on the Power/Driver board will be illuminated and the game plays normally, there will be no sound. This problem has been traced to a failure of the PCM1755DBQ digital-to-analog converter (DAC) at U16 on the S.A.M. CPU/IO MPU board. If the game is exhibiting these symptoms, the only solution is to replace U16 which is a 16-pin SSOP (shrink small outline package). This is a very small surface mount component that measures approximately 5 x 6 mm (including the chip legs). As a result, replacement should not be attempted without the proper skills and equipment. Normally, replacement of this component will return sound to the game.
 

====Volume Control Bug====
In early SAM games, if the simulated knocker is activated (the annoying loud "twip"), the sound level may increase to full volume after a replay is awarded. This is a bug in the basic operating system code. The bug was fixed in newer games but Stern didn't release updated ROMs for older games. This bug has been observed in WPT, Family Guy and Shrek. The workaround is to disable the simulated knocker. If a knocker sound is still desired, a real knocker can be installed as the games support it.

===Flipper problems===
See [[Common Flipper Troubleshooting]] for general flipper information.

Like Stern's previous system, flipper coils in SAM games are solenoid coils that are duty-cycled. Unlike traditional flippers, the flipper coil is single-wound like other solenoids. The initial "kick" is done at full power, then the coil is software duty-cycled to keep it in the "hold" up position. The EOS switch serves to tell the game when it needs to re-kick the flipper.

Unlike other systems (including WhiteStar), no diodes are required to be on the flipper coils. These have been incorporated into the solenoid driver board. A diode on the flipper coil indicates likely replacement. It won't hurt, but it does provide an opportunity to wire the coil backwards.

Mechanically, the flippers are identical to the WhiteStar flippers and use the same parts. (The design is very similar to the Williams WPC/System 11 design.)

Major wear points are the coil stop, flipper link, and coil plunger. If these have deformed (and they will, because a flipper essentially pulverizes itself during game play), the flipper will lose power and won't play as well. Every few thousand games, a rebuild kit can be installed to restore the flippers to factory performance.

Coils hum. (They jiggle in their mount.) The way they are power cycled causes some of this. They get noisier with use. Filing the plunger end and coil stop smooth can alleviate this, as would a rebuild kit.

===Pop bumper problems===

===Opto problems===
Stern's SAM era optos are a bright, visible red. Unlike Williams', Stern (and Sega and Data East) chose to show the switch as open when the opto receiver can see the sender's light, like any other switch.

Optos are connected to a board in pairs. Both the sender and receiver are the same part, so one way to verify if the receiver is working is to plug it into the sender's pins. That is, just reverse the two cables.

A common failure point for optos is that the wire breaks at the opto sender or transceiver itself. These will have to be soldered back on. Typically, the wire seems to be plain old speaker wire. The copper-colored conductor goes to the cathode 'K'; the anode 'A' gets the silver wire.

====Opto board 520-5292-00====
If there is trouble with the switch matrix, check this little opto board. It's installed in at least Batman Dark Knight, AC/DC, and several in The Rolling Stones (one is used for each position the moving Mick stops). In AC/DC, a bad board can give problems with at least the bell and the right pop bumper. If the pop bumper turns on when the ball is shot into the bell, the board is bad.

There is not much on the board. If there are general switch problems, the likeliest candidate is Q1 a BSS123 in a SOT-23 case (small) transistor. Check it with a DMM. It's a Mosfet so can not be completely checked with a DMM. On the defective board, the drain to gate pins were practically shorted.

If the opto interruptor just doesn't work, it can be replaced with a QVE11233 from Fairchild. It's the standard opto for WMS flipper boards, which is now discontinued. Stern also used a chinese substitute OS92B4. Not much can be found about it.

===Trough problems===
The trough design on S.A.M. games is identical to what was used on Whitestar games.
See [[Sega/Stern_White_Star_Repair#Trough_Opto_Boards]].

Stern opto boards at end of trough. And boards playfield optos plug onto. I've noticed when problems arise, to reflow the solder on the optos, and pins the connectors plug onto. This eliminates a lot of problems that arise with the optos. LTG :)

==References==
As of April 2014, SAM system schematics are no longer available on the Stern Pinball website.

Older manuals still have complete schematics and can be useful for troubleshooting newer games. The SAM boards did change, but connector designations generally didn't. Some manuals may be available from public sources in high-quality PDFs originally distributed by Stern Pinball.

==Game Specific Problems and Fixes==
===Pirates of the Caribbean===
The spinning disc. Check your serial numbers with the service bulletin on Stern's website. Some of the early games need to have the bearings lubricated.

And if your artwork is worn off. I've found when you put on a new decal. To put clear non-slip bath tub stuff on top of it. It works just as good at flinging the balls. And doesn't wear off as fast and get messy all over the game like the original. And easily replaced.
LTG :)

===World Poker Tour===
I bought a [[World Poker Tour]] that had been routed. When I got it, the "jail" detected balls on power-on that weren't there. Cleaning the upper playfield made it happy, since the optos assume they can see through the clear playfield. I replaced the whole upper playfield in late 2014. After a few hundred plays and three trips to California Extreme, the upper playfield was dirty enough that this problem happened again--or at least the switch became flaky. A little cleaning "fixed" it. But it's likely this will require additional cleaning every few hundred plays. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 03:07, 25 November 2017 (CST)

WPT's drop target banks may need some washers inserted as shims. Stern published [http://www.sternpinball.com/service-bulletins/service-bulletin-165-world-poker-tour service bulletin 165] with the details. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 15:35, 4 November 2014 (CST)

===Tron Pro===
Spinning disk motor dead, no power going to it. Found someone had oiled the motor which had then slung oil everywhere. Discovered oil had leeched inside the spin disc relay (assembly # 511-6919-01), burned the contacts, and blew transistor Q5 (IRL540) on the power driver board (fuse F6 was blown too). I popped the cover off the relay and cleaned out the oily mess with 99% isopropyl alcohol. Then I filed the burnt contacts and reassembled the relay. Next I replaced the bad Q5 transistor and blown fuse. That fixed the problem and the motor works again.

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.

===feature lamps not working===

If you have feature lamps not working. Check the wiring pushed into the lamp socket. I've seen more than a few where the wire isn't making good contact where it is pushed in. Easy to push in better. LTG :)

===bad opto board===

I got a brand new Star Trek. After a couple days of being played at a show, the game's technician alerts reported the left ramp entrance as not registering. After I got the game home, I discovered that the under-playfield indicator on opto board 2 registered fine (it's on until the opto is blocked, then it shuts off), and grounding the two switch matrix switches registered the switch. So there must be a failure on the board. Stern tech support sent a new board under warranty and that fixed the issue. [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 02:28, 30 July 2015 (CDT)

===Battery draining quickly===

A SAM CPU board was rapidly draining the battery when the game was powered off. Power was getting from the battery to the clock at U43 and the RAM at U11. In other words, the components on the way to the clock and RAM were good (R211, D24, R212) and the diode at D25 was also good. However, when setting the time under the Utilities menu, gibberish would be output when the last entry was accepted. This indicated a problem with the clock IC at U43. Note that U43 could set the clock correctly but still be faulty and cause quick battery drain, so don't use a successful clock update as proof that U43 is good.

The clock is a SOIC-8 150 mil package. A replacement is DS1302Z+ found at mouser.com. After replacing the clock IC the game kept correct time when powered on and off, and the battery no longer drained quickly.

Gottlieb System 80

2022-09-20T08:41:54Z

Jimpal: /* System 80B Sound Board (one button) */

Click to go back to the [[Gottlieb_Repair_Guides | Gottlieb® solid state repair guides index]].

==Introduction==

[[File:Gtb sys80 1st gen boardset.jpg‎|200px|thumb|left|Gottlieb® System 80 Board Set - 1st Generation ]] 

Gottlieb's® second generation of solid state pinballs is System 80. Capabilities were increased in terms of controllable lamps, solenoids, gameplay, and sound. No longer tied to an EM-esque platform, Gottlieb® started to introduce games with more unconventional asymmetric playfields. System 80 marked a foray into double and triple level playfields, speech, and multiball. Unfortunately, it also represented a lateral step in reliability, with battery corrosion, connectors, and bad grounding plaguing the design. Nearly all the same issues as were present with the System 1 platform.
 

[[File:System80cabinet.jpg|200px|thumb|left|Gottlieb® System 80 Board Set - 2nd Generation]] 
Just like the System 1 games, the System 80 / 80A / 80B design relied solely on connectors and daisy-chained wiring to transport the ground lines from board to board. The exception is that the large ground plane used with System 1 games was no longer used behind the boards with the System 80 games. Gottlieb® still opted to use plastic standoffs to elevate and secure the boards to the backbox or the back side of the lamp box insert. Thus, if a single ground connector failed in the chain, the logic ground could fail for one or several of the circuit boards. This could potentially lead to locked on coils, relays, and / or controlled lamps. In turn, transistors and chips would fail.
 

[[File:Later gtb sys80a boardset.jpg|200px|thumb|left|Gottlieb® System 80A Board Set]] 
The System 80 platform was used for a total of nine years from 1980-1989. During this period, there were three main versions of the boardset. These three versions are referred to as: System 80, System 80A, and System 80B. System 80 was used from 1980-1982, System 80A was used from 1982-1985, and System 80B was used from 1985-1989. The easiest way to differentiate between the three versions is by looking at the style of displays which were used. System 80 used 6-digit displays for scoring, and in some instances, for bonus values or timers. System 80A used 7-digit displays for scoring, and 6-digit displays for bonus values or timers too. Both the 6-digit and 7-digit displays were limited to displaying numeric values. System 80B differed the most by using two 20-digit alpha-numeric displays, which were stacked on top of each other.
 

[[File:Early gtb sys80b boardset.jpg|200px|thumb|left|Gottlieb® System 80B Board Set - Early]] 
Shortly after the onset of using the System 80B boardset, it was evident that the complexity of playfield designs had quickly outgrown the boardset. Remote satellite boards, and transistors littered the underside of the playfield and inside the cabinet, because the driver board was too undersized to handle these extra duties. A new boardset, known as the System 3 platform, was under development, but was not released until nearly 4 years later in 1990.
 

[[File:Typical gtb sys80b boardset.jpg|200px|thumb|left|Gottlieb® System 80B Board Set - Typical]]
[[File:GTB Later 80B Backbox.JPG|200px|thumb|right|Gottlieb® System 80B Board Set - Later Games (Hot Shots, Bad Girls, and Big House]] 
Once a System 80 / 80A / 80B game has been methodically gone through with board design grounding flaws and connectors corrected, they are just as reliable as any of their contemporaries.
 

==Games==
===System 80 Prototype===
{| class="wikitable"
!Title
!Date of Release
!Production #
!Model #
!Sound
!Display
!Notes
|-
|The Incredible Hulk || 1979 || Unknown || 500 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit || A small number of games were used as a testing platform, which featured the system 80 boardset instead of the system 1 boardset.
|}

===System 80 1st Generation===

{| class="wikitable"
!Title
!Date of Release
!Production #
!Model #
!Sound
!Display
!Notes
|-
|The Amazing Spiderman|| 05-1980 || 7625 || 653 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Panthera|| 06-1980 || 5220 || 652 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Circus|| 06-1980 || 1700 || 654 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit || Ultra Widebody
|-
|Counterforce|| 06-1980 || 3870 || 656 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Star Race|| 08-1980 || 870 || 657 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit || Ultra Widebody
|}

===System 80 2nd Generation===

{| class="wikitable"
!Title
!Date of Release
!Production #
!Model #
!  Sound  
!Display
!Notes
|-
|James Bond|| 10-1980 || 3625 || 658 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Time Line|| 12-1980 || 3167 || 659 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Force II|| 02-1981 || 2000 || 661 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Pink Panther|| 03-1981 || 2840 || 664 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit ||
|-
|Mars God of War|| 03-1981 || 5240 || 666 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 6-digit || First Gottlieb® with speech, lane change, and multi-ball
|-
|Volcano|| 09-1981 || 3655 || 667 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 6-digit || Export games used [[Media:Gtb_sys80_sound.JPG | sound only]] board
|-
|[[Black Hole]]|| 10-1981 || 8774 || 668 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 6-digit || First Gottlieb® with 2-Level playing area, Export games used [[Media:Gtb_sys80_sound.JPG | sound only]] board and a simple single backglass with no spinning disc.
|-
|[[Haunted House]]|| 06-1982|| 6835 || 669 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 6-digit || First game with 3-Level playing area, Sound only, but used sound & speech board w/o the speech chip installed.
|-
|Eclipse|| 1982 || 193 || 671 || [[Media:Gtb_sys80_sound.JPG | Sound only]] || 6-digit || Production game and available as a kit for James Bond 007
|}

===System 80A===

{| class="wikitable"
!Title
!Date of Release
!Production #
!Model #
!Sound
!Display
!Notes
|-
|Devil's Dare|| 08-1982 || 3832 || 670 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 7-digit || Export games used the [[Media:Gtb_sys80_sound.JPG | sound only]] board
|-
|[[Caveman]]|| 09-1982 || 1800 || PV810 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 7-digit || Pinball / Video game hybrid
|-
|Rocky|| 09-1982 || 1504 || 672 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 7-digit ||
|-
|Spirit|| 11-1982 || 1230 || 673 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 7-digit || Sound only, but used sound & speech board
|-
|Punk!|| 12-1982 || 959 || 674 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 7-digit || Sound only, but used sound & speech board
|-
|Striker|| 11-1982 || 910 || 675 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 7-digit || Sound only, but used sound & speech board
|-
|Krull|| 02-1983 || 10 || 676 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 7-digit ||
|-
|Goin' Nuts|| 02-1983|| 10 || 682 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound only]] || 7-digit || Sound only, but used sound & speech board
|-
|Q*bert's Quest|| 03-1983 || 884 || 677 || [[Media:Gtb_sys80%26a_s%26s.JPG | Sound & Speech]] || 7-digit ||
|-
|Super Orbit|| 05-1983 || 2100 || 680 || [[Media:Gtb sys80 sound MA483 pig.JPG | Sound Only]] || 7-digit || Sound only, but uses the less populated sound & speech board
|-
|Royal Flush Deluxe|| 06-1983 || 2000 || 681 || [[Media:Gtb sys80 sound MA483 pig.JPG | Sound Only]] || 7-digit || Sound only, but uses the less populated sound & speech board
|-
|[[Amazon Hunt]]|| 09-1983 || 1515 || 684 || [[Media:Gtb sys80 sound MA483 pig.JPG | Sound Only]] or [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit || Sound only, but uses the less populated sound & speech board. Later production games used the [[Media:Gtb_sys80a%26b_sound.JPG|sound only]] piggyback sound board
|-
|Rack 'Em Up!|| 11-1983 || 1762 || 685 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|Ready... Aim... Fire!|| 11-1983 || 390 || 686 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|Jacks to Open|| 05-1984 || 2350 || 687 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|Alien Star|| 06-1984 || 1065 || 689 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit || 689A Denotes a revision in the ROM code
|-
|The Games|| 08-1984|| 1768 || 691 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|Touchdown|| 10-1984 || 711 || 688 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|El Dorado City of Gold|| 09-1984 || 905 || 692 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|-
|Ice Fever|| 02-1985 || 1585 || 695 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || 7-digit ||
|}

===System 80B===

{| class="wikitable"
!Title
!Date of Release
!Production #
!Model #
!Sound
!Display
!Notes
|-
|Chicago Cubs Triple Play|| 05-1985 || ~1365 || 696 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || Alphanumeric; MA-644 ||
|-
|Bounty Hunter|| 07-1985 || 1220 || 694 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || Alphanumeric; MA-644 ||
|-
|Tag Team Pinball|| 09-1985 || 1220 || 698 || [[Media:Gtb_sys80a%26b_sound.JPG|Sound Only]] || Alphanumeric; MA-644 ||
|-
|Rock|| 10-1985 || 1875 || 697 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 || DIP switches 7 and 8, while listed as "spares", 7 is actually used to turn attract sounds on / off. There is an addendum added to the first page of the manual stating as such.
|-
|Raven|| 03-1986 || 3550 || 702 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Rock Encore|| 04-1986 || 245 || 704 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||Production game using same playfield art as Rock, but mainly available as a conversion kit for Rock
|-
|Hollywood Heat|| 06-1986 || 3400 || 703 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Genesis|| 09-1986 || 3500 || 705 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Gold Wings|| 10-1986 || 3260 || 707 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Spring Break|| 04-1987 || 3550 || 706 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Monte Carlo|| 02-1987 || 4315 || 708 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]|| Alphanumeric; MA-644 ||
|-
|Arena|| 06-1987 || 3099 || 709 ||[[Media:GTB Sys80B Sound.JPG|Sound Only]]||Alphanumeric; MA-644 ||
|-
|Victory|| 10-1987 || 3315 || 710 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-644 ||
|-
|Diamond Lady|| 02-1988 || 2700 || 711 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-644 ||
|-
|TX Sector|| 03-1988 || 2336 || 712 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-644 ||
|-
|Robo-War|| 04-1988 || 2130 || 714 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-644 ||
|-
|Excalibur|| 11-1988 || 1710 || 715 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-999 ||Start of the MA-1133 CPU Board. No actual speech callouts are present in this game.
|-
|Bad Girls|| 11-1988 || 2500 || 717 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-999 ||
|-
|Big House|| 04-1989 || 1977 || 713 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-999 ||
|-
|Hot Shots|| 04-1989 || 2342 || 718 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-999 ||
|-
|Bone Busters Inc.|| 08-1989 || 2000 || 719 || [[Media:Gtb sys80b MA886 sound.JPG|Sound & Speech]]|| Alphanumeric; MA-999 || Uses 3 sound boards - uses 50v to power flippers
|-
|}

Game date of release, production numbers, and model number provided by the Internet Pinball Database - http://www.ipdb.org

==Documentation==
===Recommended Documentation===
====Manuals====
* A game manual. Pinball Resource has many factory originals still left, and reprints of everything else.

====Theory of Operation & Repair Guides====

{| class="wikitable"
|-
!Catalog
!Cover
!Source
!Notes

|-
|Gottlieb Star Series 80 Service Manual
|[[file:Gottlieb-star-series-80-service-manual-cover.jpg|thumb|left|140px]][[file:Gottlieb-star-series-80-service-manual-cover-alt.jpg|thumb|left|140px]]
|[http://www.pbresource.com/books.html PBResource.com]
|Information on how system 80 operates, with troubleshooting information outlined.

|-
|1983 Technical Seminar Workbook
|[[file:placeholder.jpg|thumb|left|140px]]
|[http://www.pbresource.com/books.html PBResource.com]
|Information on how system 80 operates, with troubleshooting information outlined.

|}

====Parts Catalogs====
Parts catalogs can also be useful, which include part numbers (helpful for purchasing parts online), exploded views of assemblies (helpful to see how the assemblies are put together), and board layouts & schematics, and diagrams for controlled lamp, solenoid, and rubber locations. Gottlieb tended to publish a lot of game-specific information in parts catalogs. These have exploded diagrams of assemblies, particularly in earlier games that had the thinner, much less helpful manuals. Playfield parts, lamps, and switches are all diagrammed out. These also have collected service bulletins. Reprints are available from Pinball Resource.

{| class="wikitable"
|-
!Catalog
!Cover
!Source
!Games
!Notes

|-
|1982 Parts Catalog
|[[file:gottlieb-1982-parts-catalog-cover.jpg|thumb|left|140px]]
|[http://www.pbresource.com/books.html PBResource.com]
|Counter Force, Star Race, James Bond, Time Line, Force II, Pink Panther, Mars God Of War, Volcano, Black Hole, Haunted House, Devil's Dare, Caveman, Rocky. This catalog also features system 1 games.
|Includes parts assemblies, plus switch matrix and controlled lamp locations, board layouts, schematics, and board parts lists, coin door parts, and some cabinet parts. Includes System 1 and 80 parts and boards.

|-
|1987 Parts Catalog
|[[file:gottlieb-1987-parts-manual-cover.jpg|thumb|left|140px]]
|[http://www.pbresource.com/books.html PBResource.com]
|Volcano, Black Hole, Haunted House, Devil's Dare, Rocky, Spirit, Rock, Striker, Q*bert's Quest, Super Orbit, Royal Flush, Amazon Hunt, Rack 'Em Up, The Games, Chicago Cubs Triple Play, Rock Encore, Ready Aim Fire, Touchdown, Bounty Hunter, Raven, Jacks To Open, El Dorado City Of Gold, Tag Team, Hollywood Heat, Alien Star, Ice Fever, Rock, Genesis
|

|-
|1992 Parts Catalog
|[[file:gottlieb-1992-parts-manual-cover.jpg|thumb|left|140px]]
|[http://www.pbresource.com/books.html PBResource.com]
|Covers 80B games starting from Gold Wings and the first 9 System 3 titles (games #706-#730).
|
|}

One interesting note about the part numbers is that the single letter that preceded the number indicated the size of the paper that was used for the original drawing/blueprint of the part. Paper sizes A up through F were used.

===Connector Designations===
All Gottlieb® machines have a common naming convention for all of the connectors in the game. A specific connection uses two parts - a prefix and a suffix. The prefix is the board number or an inline wire junction, and the suffix is the connection on the board or a sequential wire junction number. When referencing a specific connector pin within a housing, a dash follows the connection number. For example, the connector pin for the slam switch signal on the CPU board is A1J5-10. The coin door connection used on Devil's Dare is A15P1 and A15J1 - the connector pin for switch return 7 on the coin door is A15J1-8. 

The following boards are assigned the same numbers throughout the System 80 / 80A / 80B platforms.
*CPU Board - A1
*Power Supply - A2
*Driver Board - A3
*Sound Board - A6
*Pop Bumper Driver Boards - A8
*Reset Board - A24
 
There are several other board designations used, however, they change from game to game.
 

===The Wiring Color Code===

Unlike every other pinball manufacturer, which adopted a two-color wiring code system, Gottlieb® used three colors. Most wiring in a Gottlieb® game used a white base color, which is the wire's insulation color, and three "striped" traces on each wire. I state most cases, because there are some wires which only used two colors - the green insulated ground lines which have a single yellow trace, or only one color - the white ground wires used in System 80B games with no trace at all. Below is the Gottlieb® color chart.
{| class="wikitable" style="margin: 1em auto 1em auto;"
!
!0
!1
!2
!3
!4
!5
!6
!7
!8
!9
|-
| Color || Black
|| Brown 
|| Red 
|| Orange 
|| Yellow 
|| Green 
|| Blue 
|| Purple 
|| Gray 
|| White 
|}
Does the color chart look familiar? Well, if you have an electronics background, it should. The Gottlieb® wire code system is the same as the resistor color coding system.

Here are some examples of the color coding system. The color wire code for switch strobe line 0 is 400. 400 would be a white insulated wire with a yellow trace and two black traces, or commonly referred to as a yellow-black-black wire. The ground lines in early System 80 games are code 54. 54 would be a green insulated wire with one yellow trace.

There is one word of caution, which should be pointed out. If the connections on A1J2 and A1J3 are being replaced, there are wire colors on these connections which are very similar. Although each wire is located on a different housing, please proceed with caution, as it can be difficult to see all three traces without spinning the wire around. The wires which come to mind are 344 and 677 on A1J2, and 433 and 766 on A1J3.
 

===Switch Matrix===
====Switch Matrix Wire Coloring====
[[File:GottliebSystem80A1J6SwitchMatrixWireColors.png|right|thumb|500px|Gottlieb® System 80 Switch Matrix Wire Coloring at Connector A1J6. Illustration provided with permission of Sascha Voskuil aka Zaza.]]
Wire colors used for the switch matrix, as connected to A1J6 on the MPU, were identical across all Gottlieb System 80/80A/80B games. They are, from pin 1 to 19, and right-to-left (backwards) as you view the front of the connector as installed on the MPU...
#yellow-black-black
#yellow-brown-brown
#yellow-red-red
#yellow-orange-orange
#yellow-yellow-yellow
#yellow-green-green
#yellow-blue-blue
#yellow-purple-purple
#white (ground)
#blue-black-black
#blue-brown-brown
#blue-red-red
#blue-orange-orange
#blue-yellow-yellow
#blue-green-green
#blue-blue-blue
#blue-purple-purple
#blue-slate-slate (+5VDC)
#empty

Note: that not all games use all rows and/or all columns of the switch matrix. Unused switch matrix circuits are not wired.
 

====Switch Matrix Switch Numbering====
[[File:Sys80 switch matrix.png|left|thumb|600px|Gottlieb® System 80 Switch Matrix]]
The Gottlieb® System 80 / 80A / 80B switch matrix consists of a maximum of 64 switches. There are a total of 8 switch strobes and 8 switch returns. However, not every switch in the matrix is used on every System 80 game.

Just like the System 1 switch numbering system, the System 80 switch numbers have a similar naming convention. Except, the System 80 switch numbering system is the opposite of System 1. If you are accustomed to working on System 1 games, pay close attention. With Gottlieb® System 80 switches the first number of the switch is its strobe number, while the second number is switch's return number. An example would be switch 54. Switch 54 is located on strobe 5 and return 4 of the switch matrix.

{| class="wikitable"
!
!Strobe 0 
(A1J6-1 / A1J5-2) 
!Strobe 1 
(A1J6-2 / A1J5-3) 
!Strobe 2 
(A1J6-3 / A1J5-4) 
!Strobe 3 
(A1J6-4 / A1J5-5) 
!Strobe 4 
(A1J6-5 / A1J5-6)
! Strobe 5 
(A1J6-6 / A1J5-7) 
!Strobe 6 
(A1J6-7)
!Strobe 7 
(A1J6-8 / A1J5-9) 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 0 (A1J6-10) 
| style="vertical-align: top; text-align: center;" | 00 
| style="vertical-align: top; text-align: center;" | 10 
| style="vertical-align: top; text-align: center;" | 20 
| style="vertical-align: top; text-align: center;" | 30 
| style="vertical-align: top; text-align: center;" | 40 
| style="vertical-align: top; text-align: center;" | 50 
| style="vertical-align: top; text-align: center;" | 60 
| style="vertical-align: top; text-align: center;" | 70 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 1 (A1J6-11) 
| style="vertical-align: top; text-align: center;" | 01 
| style="vertical-align: top; text-align: center;" | 11 
| style="vertical-align: top; text-align: center;" | 21 
| style="vertical-align: top; text-align: center;" | 31 
| style="vertical-align: top; text-align: center;" | 41 
| style="vertical-align: top; text-align: center;" | 51 
| style="vertical-align: top; text-align: center;" | 61 
| style="vertical-align: top; text-align: center;" | 71 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 2 (A1J6-12) 
| style="vertical-align: top; text-align: center;" | 02 
| style="vertical-align: top; text-align: center;" | 12 
| style="vertical-align: top; text-align: center;" | 22 
| style="vertical-align: top; text-align: center;" | 32 
| style="vertical-align: top; text-align: center;" | 42 
| style="vertical-align: top; text-align: center;" | 52 
| style="vertical-align: top; text-align: center;" | 62 
| style="vertical-align: top; text-align: center;" | 72 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 3 (A1J6-13)
| style="vertical-align: top; text-align: center;" | 03 
| style="vertical-align: top; text-align: center;" | 13 
| style="vertical-align: top; text-align: center;" | 26 
| style="vertical-align: top; text-align: center;" | 33 
| style="vertical-align: top; text-align: center;" | 43 
| style="vertical-align: top; text-align: center;" | 53 
| style="vertical-align: top; text-align: center;" | 63 
| style="vertical-align: top; text-align: center;" | 73 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 4 (A1J6-14) 
| style="vertical-align: top; text-align: center;" | 04 
| style="vertical-align: top; text-align: center;" | 14 
| style="vertical-align: top; text-align: center;" | 24 
| style="vertical-align: top; text-align: center;" | 34 
| style="vertical-align: top; text-align: center;" | 44 
| style="vertical-align: top; text-align: center;" | 54 
| style="vertical-align: top; text-align: center;" | 64 
| style="vertical-align: top; text-align: center;" | 74 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 5 (A1J6-15) 
| style="vertical-align: top; text-align: center;" | 05 
| style="vertical-align: top; text-align: center;" | 15 
| style="vertical-align: top; text-align: center;" | 25 
| style="vertical-align: top; text-align: center;" | 35 
| style="vertical-align: top; text-align: center;" | 45 
| style="vertical-align: top; text-align: center;" | 55 
| style="vertical-align: top; text-align: center;" | 65 
| style="vertical-align: top; text-align: center;" | 75 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 6 
(A1J6-16 / A1J5-8) 
| style="vertical-align: top; text-align: center;" | 06 
| style="vertical-align: top; text-align: center;" | 16 
| style="vertical-align: top; text-align: center;" | 26 
| style="vertical-align: top; text-align: center;" | 36 
| style="vertical-align: top; text-align: center;" | 46 
| style="vertical-align: top; text-align: center;" | 56 
| style="vertical-align: top; text-align: center;" | 66 
| style="vertical-align: top; text-align: center;" | 76 
|-
| style="vertical-align: top; text-align: center; font-weight: bold;" | Return 7 
(A1J6-17 / A1J5-1) 
| style="vertical-align: top; text-align: center;" | 07 
| style="vertical-align: top; text-align: center;" | 17 
| style="vertical-align: top; text-align: center;" | 27 
| style="vertical-align: top; text-align: center;" | 37 
| style="vertical-align: top; text-align: center;" | 47 
| style="vertical-align: top; text-align: center;" | 57 
| style="vertical-align: top; text-align: center;" | 67 
| style="vertical-align: top; text-align: center;" | 77 
|}
 

====The "Missing" Gottlieb® System 80 Switches====

With the Gottlieb® System 80 series of games, there are some switch assignments that are designated the same throughout the System 80, 80A, and 80B platforms. These switches are typically not listed in the switch matrix portion of the manual. You have to review the cabinet schematics, and decipher what switches use what return and strobe. However, it appears that Gottlieb® / Premier® changed this section of the schematic starting with Excalibur or Bad Girls by no longer listing the strobes for these switches. So, below are the "missing" switch assignments for any Sys80B. All the info applies for Sys80 and Sys80A, except the two advance buttons, which weren't used prior to Sys80B. 

     '''06''' - left advance button, also pause both lamp and relay/ solenoid tests (Sys80B only) 
     '''07''' - play / test switch 
     '''16''' - right advance button (Sys80B only) 
     '''17''' - left coin switch 
     '''27''' - right coin switch 
     '''37''' - center coin switch 
     '''47''' - replay button 
     '''57''' - plumb bob and ball roll tilts (these have the same switch assignment as the playfield tilt switch) 
Black Hole is an exception. The switch assigned for the tilt on Black Hole is 26. 
Note: The coin door slam switch is not part of the switch matrix. 

=== Language Selection ===

The only way to change the language displayed is to install the correct language ROMs. Gottlieb didn’t incorporate a “soft” method of changing language selection.

===Enabling Free Play===
Free play options were unavailable in the original System 80/80A/80B game code. However, there are some hardware modifications that can be done, stacked switches can be added to the start/credit button, or EPROMs with free play code can replace original PROMs.

====Free Play EPROMs====
For system 80/80A, the U2/U3 PROMs can be replaced with an [http://www.flipprojets.fr/Freeplay_EN.php EPROM with free play code]. Replacing U2/U3 will require an adapter, such as the [https://www.greatplainselectronics.com/proddetail.asp?prod=140-101 module from GreatPlainsElectronics], a [http://www.actionpinball.com/tech/sys80mod.php#system custom adapter board], or the Swemmer Electornics U2/U3 Adapter.

For System 80B, the game PROM can be replaced with an [http://www.flipprojets.fr/Proms80B_EN.php EPROM with free play code].

====Free Play for System 80 Games====
Early Gottlieb® solid state pinball machines, prior to 1990, did not have a free play option available within the game settings. With this simple modification, a game can be set up for free play. First, identify the diode strip in the bottom of the cabinet. Once the diode strip is found, locate the credit button and coin switch strobe line wires. The wires will be located on the left of the diode strip - the non-banded side of the diodes. Below is a list of the wires.

* Credit button wire - Green-Yellow-Yellow
* Left coin switch wire - Green-Brown-Brown
* Center coin switch wire - Green-Orange-Orange
* Right coin switch wire - Green-Red-Red

[[File:Gtbsys80board.jpg|300px|thumb|left|Typical location of System 80 diode board in cabinet]]
[[File:System80FreePlayJumper.jpg‎|300px|thumb|right|Gottlieb® System 80 Black Hole diode board with jumper (yellow wire) to implement free play]]

Solder a small lead wire from the credit button wire to any of the coin switch wires. The wires will change to different colors on the other side of the diode. You want to solder to the side of the diode (non-banded) with the color wire specified above.

Make sure that the diode, credit button wire, and coin switch wire are still soldered securely to the diode strip terminal when finished. If soldering is not an option, use a small alligator clip test lead. Now, when the credit button is pressed, a credit will be incremented and decremented. A game can be easily started without the need to open the coin door to trip the coin switches anymore.

For this "hack" to work properly (adding a credit and then decrementing a credit), the MPU DIP switches for the associated coin chute must be configured so that one coin drop adds one credit. In other words, if the DIP switches are set to require more than one coin drop through the associated chute, the free play "hack" will not work correctly because the "hack" mimics a single coin drop.

Please note that this modification does not apply to Gottlieb® System 80A and System 80B machines. System 80A and 80B machines use diode boards with edge connections, which are typically located on the cabinet wall near the left flipper cabinet switch. Jumpering the diodes on System 80A and 80B games do not give the intended free play results of jumpered System 80 diodes. This is attributed to how the diode boards are physically placed differently in circuit with respect to the switches.
 

[[File:TimeLineFreePlay.jpg‎|300px|thumb|left|Gottlieb® System 80 Time Line diode board with jumper (the red wire...I mean...it's a red flippin' wire. You HAVE to be able to see it!) to implement free play]] 
The picture at left ties the center coin chute wire (Green-Orange-Orange) to the credit button wire (Green-Yellow-Yellow).
 

====Free Play for System 80A Games====
There is no method to implement free play for System 80A games at this time, other than "stacking" the credit button switch with one of the coin drop switches.
 

====Free Play for System 80B Games====
A System 80B game does not have a built-in free play option available, so the fallback option to add credits is usually to open the coin door and trip the coin switches. However, there are a couple of methods that can be used to avoid doing that.

=====Free Play Diode Board Modification=====
Locate the diode board used for all of the coin door switches. Remove the diode board. Add a jumper between pin 4 and pin 10 of the diode board on the solder side of the board, (this can be done on the component side instead). Make certain that the jumper is soldered onto the banded side of the diodes. This jumper essentially ties the right advance button on the front of the cabinet to the center coin switch.

Now, when the right advance button is pressed, credits will be added to the game. There have not been any ill side effects observed when the right advance button is pressed while scrolling through characters used to enter high score initials.

An alternative method that achieves the same result is to use a jumper wire with minigrabber ends and clip them on to the bottom of the 4th and 9th diodes (from the right) on the front of the board. This requires no soldering and you don't even have to remove the diode board.

The jumper modification should work on games from Chicago Cubs Triple Play to Excalibur. It is unconfirmed if it will work on Hot Shots, Bad Girls, Big House, and Bone Busters, Inc.

<gallery widths=400 class=center>
File:GTB_Sys80B_Coin_Door_Diode_Board.JPG|Typical location of System 80B diode board on cabinet wall
File:GTB_Sys80B_Coin_Door_Diode_Board_Jumper_Added.JPG|Added jumper to back of diode board
File:GTB_Sys80B_Coin_Door_Diode_Board_Jumper_Location_Front.JPG|Location to add jumper to front of diode board
File:GTB_Sys80B_Coin_Door_Diode_Board_Jumper_Added_To_Front.JPG|Added minigrabber jumper to front of diode board
</gallery>

=====Free Play ROM=====
Another option is a free play ROM, produced by a group of kindly fellows in France. By burning the revised image into a 2764, and installing the new ROM on the daughter card, the game will now be on free play. Their implementation notices when zero credits are on the game and the credit button has been pressed. The new code then adds 20 credits to the game, and starts a game. The System 80B free play ROMs can be found [http://www.flipprojets.fr/Proms80B_EN.php here].

=== Bookkeeping & Diagnostics ===
[[File:GTB sys80 test button.jpg|300px|thumb|left|Gottlieb® System 80 Coin Door Test Button Highlighted]] 
To enter the bookkeeping / diagnostic mode, open the coin door and press the red momentary switch. (Note this switch has no credit function) Depending on the particular game, the self test button may be mounted on a bracket located on the coin door or just inside the cabinet near the coin door hinge. Upon pressing this button, the 4-digit status display used with System 80 and System 80A games will display "'''00'''" in the credit window. Pressing the self test button again will advance to the next step in the bookkeeping. 

There is an option to bypass all of the bookkeeping functions, entering diagnostic mode directly. To achieve this, the self test button must first be pressed. "'''00'''" will shown on the status display. Then, the credit / start button should be pressed once. The status display should now show "'''16'''". "'''16'''" is the first test in diagnostic mode. 

Bookkeeping (System 80/80A) 
1 - Coins thru left chute 
2 - Coins thru right chute 
3 - Coins thru center chute 
4 - Total plays 
5 - Total replays 
6 - Game percentage 
7 - Extra ball 
8 - Total tilts 
9 - Total slam tilts 
10 - Number of times the HSTD has been beaten 
11 - First high score level 
12 - Second high score level 
13 - Third high score level 
14 - High score to date score 
15 - Average game time 

Diagnostics 
16 - Lamp test 
17 - Coil test (will cycle and display coil number of coils used in the game. Coin counter coils, if installed, are excluded) 
18 - Switch test. (99 = no switches closed) You can check switch numbers by pressing them on the playfield during this step. 
19 - Display test. The displays will cycle through each digit 
20 - Memory test. (99 = no fault) 

[[File:System80-7641-2Error.jpg|300px|thumb|left|Gottlieb® System 80 "7641" Error]] 
An example of a ROM image checksum error (or perhaps a ROM memory access error) displayed during test 20 is pictured at left. During test 20, if a checksum error is detected, the ROM code in U2/U3 will indicate "7641-X" in the player 1 display window, with "X" being "1" to indicate PROM 1 or "2" to indicate PROM 2. If you have followed the procedure to combine the original game ROMs into a single 2716, this error message is an indicator that the checksum of either the 1st half or the 2nd half of that ROM failed. Replace the ROM. 

[[File:System80A5101.jpg ‎|300px|thumb|left|Gottlieb® System 80A "5101" Error]] 
An example of a probable 5101 CMOS RAM error (or perhaps a CMOS RAM memory access error) displayed during test 20 of a System 80A "Spirit" game is pictured at left. During test 20, if a RAM error is detected, "5101" will be displayed in the player 1 display window. 

System 80B uses the same process as System 80/80A to enter bookkeeping / diagnostics. The only difference is upon pushing the self test button the first time, the top alphanumeric display will display "'''TEST MODE'''". Pressing the self test button again will enter bookkeeping mode, while pressing the credit / start button will enter diagnostics mode. After entering either mode, pressing the self test button will advance through each step in the appropriate mode. 

[[File:System80BZ5Error.jpg ‎|300px|thumb|left|Gottlieb® System 80B "ERROR- Z5"]] 
System 80B memory test will throw a memory error, "ERROR- Z5" as shown at left. This could indicate a failed 5101 (most likely) or it could mean that the processor can not access the 5101 due to chip select, address signal line, or data line signal line issues. 

The following notes apply to all System 80/A/B games.
*Any diagnostic test can be repeated by pressing the credit / start button.
*Waiting 60 seconds will reset the CPU and return the game to attract mode.
*The slam switch or tilt switch can be triggered to exit diagnostics. This is probably the only benefit of keeping the slam switch functional. However, considering the sometimes strange side effects which can arise from a maladjusted or malfunctioning slam switch, [[Gottlieb_System_80#Slam_Switch_Modification | disabling the slam switch]] is generally a better idea. 

====Default High Score To Date (HSTD)====
If a high score to date is not explicitly set (setting 14), then some (most) games use a default HSTD of either 770,000 or 790,000.

====Pausing the Lamp and Solenoid Test (System 80B Only)====
[[File:Gtb sys80B left advance.jpg|left|thumb|300px|The left advance button on a System 80B Game]] 
The following only applies to System 80B lamp and solenoid tests. A little known fact is that the lamp and solenoid tests can be "paused" on a single lamp or single solenoid. To stop whichever item is being tested during lamp or solenoid test, and repeat the test on the particular item, simply push and hold in the left advance button located on the front of the cabinet, as shown in the picture to the left. The left advance button can then be released, pressed, and held in again to step to the next item in the test. This is a particularly nice feature, because the lamps and solenoids or relays tend to be pulsed rather quickly in test, and cannot be observed very well, until the test repeats itself. 

===Rubber Ring Chart===
Although the Gottlieb® System 80 game manuals do list the location and part numbers for rubber rings used, some fail to list the actual rubber ring size. Below is a handy chart, which lists the Gottlieb® rubber OEM number and its size. 

{| class="wikitable"
!Gottlieb® #
!Description
|-
|A-14793 ||23/64" White Mini-Post
|-
|A-15705 ||27/64" White Mini-Post
|-
|A-10217 ||5/16" White Ring
|-
|A-17493 || 7/16" White Ring
|-
|A-10218 || 3/4" White Ring
|-
|A-10219 || 1" White Ring
|-
|A-10220 || 1-1/2" White Ring
|-
|A-10221 || 2" White Ring
|-
|A-10222 || 2-1/2" White Ring
|-
|A-10223 || 3" White Ring
|-
|A-10224 || 3-1/2" White Ring
|-
|A-10225 || 4" White Ring
|-
|A-10226 || 5" White Ring
|-
|A-13151 || 3/8 x 1-1/2" Standard Red Flipper
|-
|A-13149 || 3/8 x 1" - Small Beaded Red Flipper
|-
|A-1344 || Rebound Rubber
|-
|1872 || Shooter Tip
|}

 

==Technical Info==

===[[System 80 / 80A / 80B Board Set]]===
Clicking the link above will direct you to a new page showing all of the System 80/80A/80B boards. 

[[File:Gtb sys80 boards 3.png‎|800px|center|Gottlieb® System 80 Board Diagram]]
 

The following functional block diagram depicts the main PCBs and the input/output signals between them (#n = wire count). 
[[File:sys80b_IO_lines.png|800px|center|Gottlieb® System 80/B functional blocks and I/O lines]]
 

===[[System 80 / 80A / 80B Satellite Boards]]===
Clicking the link above will direct you to a new page showing all of the System 80/80A/80B satellite boards. 

===Power Supplies===

====System 80 / 80A Power Supply====

[[File:Gtb sys80 psu.JPG‎|300px|thumb|left|System 80 / 80A Power Supply]]
[[File:Gtb sys80 psu back.JPG|300px|thumb|right|System 80 / 80A Power Supply - Showing the Large Heat Sink]] 
The System 80 / 80A power supply is very similar to the System 1 power supply, where as the circuit board is secured to a large "hot plate" heat sink. This style power supply is used for all System 80 and 80A games from Spiderman to Ice Fever, and is the source of the following:
* +5 VDC logic power
*+8 VDC offset voltage needed for the displays
*+60 VDC for the 6 or 7 digit displays
*+42 VDC for the status display
*Ground from earth ground located on the transformer panel 

Unlike the System 1 power supply, the +5 VDC logic power is no longer rectified and filtered on the power supply itself. This process is now handled by a bridge rectifier and a large filtering capacitor located on the transformer panel. The System 80 power still employs a [http://en.wikipedia.org/wiki/Crowbar_%28circuit%29 crowbar circuit] for the logic power, which protects from over-voltage situations.
 

Although these power supplies are fairly reliable, there are some drawbacks to the design. By incorporating a large heat sink for the PMD10K40 / 2N6059 TO-3 transistor on the board, a lot of heat is dissipated throughout the whole board. This in turn will limit the life expectancy of the other electronic components on the board. Equally, the heat sink must be removed in order to perform component level repairs to the board.
 

====System 80 / 80A Sound & Speech Power Supply====

A sound & speech board (S&S) is used starting with Mars God of War (MGOW). Because of the voltages needed to drive some of the components on the S&S board, this secondary power supply is added to the power train. The voltages generated from this board are:
*+12 VDC used for the analog inverters and voice synthesizer chip
*-12 VDC used for the analog inverters
*+30 VDC used by the sound amplifier (LM379)
 

[[File:Gtb sys80 sands power1.JPG|300px|thumb|left|System 80 Sound & Speech Power Supply (1st Generation)]] 
There are two different variations of this power supply. The first style is used only with MGOW and Volcano, and is not a printed circuit board (PCB). The electronic components were screwed to a block of wood, which is located on the left wall of the lower cabinet. Conducting tests and repairs to this style power supply can be awkward and difficult.
 

[[File:GTB Sys80 s&s psu.JPG|300px|thumb|left|System 80/80A Sound & Speech Power Supply (2nd Generation)]]
[[File:System80SpeechAndSoundPS.jpg|300px|thumb|right|System 80/80A Sound & Speech Power Supply (2nd Generation), with test points added. Unstuffed component locations facilitate easy addition of voltage test points The ground test point requires a hole to be drilled in the PCB. Negative 12V is measured at the non-banded end of the 1N4742 zener diode.]] 
Starting with Black Hole, the S&S power supply is now on a circuit board (MA-188), which is located in the head of the game with the other circuit boards. Even though each style of S&S power supply uses different components for the generation of +12 VDC, the end result is the same. The S&S power supply was no longer used when Gottlieb® went a step backwards, and installed the System 80A sounds only board with the piggyback board. This change occurred during the run of Amazon Hunt.
 

Note: The generation 1 and generation 2 sound board power supplies are not pin compatible. One could be exchanged for the other by rearranging connections of a 9-pin molex connector. However, this is not recommended.

====System 80B Power Supplies====

Starting with Chicago Cubs, the Gottlieb® power train went through a bit of a face lift. The System 80B platform uses two separate boards to supply power. This design change is mainly due to the single display board, which rectifies the high voltage on the board itself. 

[[File:Gtb sys80b psu.JPG|300px|thumb|left|System 80B +5 VDC Power Supply]] 
The small power supply with the finned heat sink is only used to generate +5 VDC for logic power. Although, removing the heat sink is not necessary to work on the board, this power supply has its own set of issues. First, it does not have a crow bar circuit. If the LM338K voltage regulator fails, and fails whereas the voltage increases drastically, it can destroy electronic components on the other circuit boards. Secondly, it's not as bad, but heat is still dissipated throughout the board. Third, the adjustable potentiometer (pot) on the power supply is prone to failure, due to dirt, dust, and contaminants. Finally, it is typical for the header pins on the input and output of the board to develop cracked solder joints. The two latter problems can easily be overcome, and will be addressed in the [http://pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Recommended_Repairs_for_the_System_80B_Power_Supply_Board Recommended Repairs for the System 80B Power Supply Board] section below.
 

[[File:Gtb sys80b aux psu.JPG|300px|thumb|left|System 80B Auxiliary Power Supply]] 
Starting with Rock, the second power supply is added, and is referred to as the auxiliary power supply. The primary functions of this board is used to power the sound board, and amplify the audio output. This sound amplifier board is used in concert with MA-766 and MA-886 sound boards. A breakdown of the voltages supplied by the auxiliary power supply are as follows:
*-12 VDC
*+12 VDC
 

[[File:GottliebSystem80B-MA1017AuxPowerSupply.jpg |300px|thumb|left|System 80B Auxiliary Power Supply with .156 headers versus edge connector]]
[[File:BoneBustersSpecificAmpBoard.jpg |300px|thumb|right|A BoneBusters Inc specific Auxiliary Power Supply]] 
This Auxiliary Power Supply board changed with the release of Bad Girls. Edge connections were no longer used. Instead, .156" header pins were added to the board as shown at left. Note that the System 80B Auxiliary Power Supply board is slightly different from the System 3 Auxiliary Power Supply board. The System 80B board uses a 1K ohm, 2 watt resistor at R8. The System 3 board uses a 330 ohm 1/2 watt resistor at that location.

[http://www.ipdb.org/machine.cgi?id=347 Bone Busters Inc.] uniquely used a modified Auxiliary Power Supply board as pictured at right. A connection was made between pin 12 and the intersection of R1 and R2 to connect the audio output of the second, less populated sound board to the amplifier circuitry. A 1.8K ohm 1/4 watt resistor makes the connection while balancing the audio level from this input. No other game used pin 12 or this configuration.
 

===CPU Board===
[[File:Gtb sys80 cpu divided.png‎|300px|left|thumb|Gottlieb® System 80 CPU Board]] 
The System 80 CPU board is a 6502 based microprocessor system. The 6502 microprocessor (the very same one used in the first Apple computer and the Atari 2600) executes the basic operating system contained in the masked ROMs at U2/U3. The masked ROMs at U2 and U3 have the same code for all of the different generations of the System 80 platform. U2 and U3 code changed with the System 80A platform. The game code "personality" augments the basic operating system PROM(s). Early System 80 games which used two ROMs at PROM1 and PROM2 positions were masked ROMs. Later, when the game code could be held in a single 2716, an EPROM was used instead. Battery-backed memory for audits and adjustable game parameters is added via a 5101 256x4 bit CMOS memory at Z5. "Scratchpad" memory is contained in the three 6532 RIOTs.
 

Control of peripheral devices (in this case lamps, displays, solenoids, switches and sound) is accomplished via three 6532 RIOTs (RAM-I/O-Timer) at U4, U5, and U6. Each RIOT in turn controls it's own "subsystem" to drive these devices.

*Switch matrix (U4)
*Displays (U5)
*Solenoids (U6)
*Lamps (U6)
*Sound (U6)

There are four generations of the System 80 board. All of the CPU boards can be easily identified by their revision numbers notated just below the operator adjustable dip switches.
 

====1st Generation CPU Board====
[[File:GTB sys80 CPU 1st ver.JPG|300px|thumb|left|System 80 CPU Board - 1st Generation]] 
The first generation CPU is used in the first 5 System 80 games, and is marked with the following:
*ASSY PB03-D100-001
*DET PB03-D102-001
*REV B
This board uses two masked PROM chips for the game code. The chips are typically labeled with the three digit game model number followed by /1 or /2, designating the game PROM position. An example of this naming convention is shown in the pic to the left. 652/1X and 652/2X are game PROM 1 and PROM 2 for Panthera. The "X" in this case designates a code revision. The masked ROMs at position U2 and U3 are not socketed on this board. 
With some simple modifications, this board is upward compatible to use a single 2716 EPROM placed in the PROM 1 socket of the board. With the change of U2 and U3, this board can be used in System 80A games. The board could potentially be used in a System 80B game with many modifications, and the addition of a daughter board, however, it is not recommended.
 

[[File:EarlySystem80MPUFactoryCutJumper.jpg|300px|thumb|left|The corrected trace layout error in the 1St generation System 80 MPU]] 
This generation of board has a trace layout error that was corrected by a cut and jumper which moves the trace that terminates at Z5 (5101) pin 20 from Z36 pin 10 to pin 9.
 

[[File:GTB sys80 cpu front scale.png|300px|thumb|left|System 80 CPU Board - 1st Generation (Front)]]
[[File:GTB sys80 cpu back scale.png|300px|thumb|right|System 80 CPU Board - 1st Generation (Back)]] 
The "skeletal", semi-populated board scans can be very useful when having to replace or follow traces on a CPU board. Although the scans are of the 1st generation CPU board, most areas can be used for other generation CPU boards too.
 

====2nd Generation CPU Board====
[[File:Placeholder.jpg|300px|thumb|left|Placeholder for System 80 CPU Board - 2nd Generation]]
The second generation CPU is used in some System 80 games, and is marked with the following:
*ASSY PB03-D100-??? (check boards for the suffix)
*DETAIL PB03-D107-001
This board uses a single 2716 EPROM chip for the game code located at the PROM 1 socket position. The chips are typically labeled with the three digit game model number. Occasionally, the chip's game number label will be followed by /1, /2, /3, or even /4. In this case, the number following the slash is the code revision number. An example of this naming convention is 658 /2, which is a game PROM for James Bond - code revision 2. The masked ROMs at position U2 and U3 are not socketed on this board either. 
With the change of U2 and U3, this board can be used in System 80A games. The board could potentially be used in a System 80B game with many modifications, and the addition of a daughter board, however, it again is not recommended. The second generation CPU is backward compatible, provided a doubled up, single game PROM is used at the PROM 1 position.
 

====3rd Generation CPU Board====
[[File:GTB sys80 CPU 2nd gen.JPG|300px|thumb|left|System 80 CPU Board - 3rd Generation]]
The third generation CPU is used in some System 80 games, and is marked with the following:
*ASSY PB03-D100-011
*DETAIL PB03-D107-003
This board is essentially the same as the second generation board, except an eyelet ground trace was placed just above Z33 on the board. This ground trace was never used. All information which applies to the second generation CPU board, applies to this board. The third generation CPU is backward compatible, provided the same is done to it as the 2nd generation board.
 

====4th Generation CPU Board (System 80A)====
[[File:GTB sys80A CPU.JPG|300px|thumb|left|System 80A CPU Board]] 
The fourth generation CPU is used in all System 80A games, and is marked with the following:
*D 20869
This board is the same as the third generation board, except the U2 and U3 masked ROM chips have different code, and are now socketed. The PROM 2 socket is no longer populated on the board. The fourth generation CPU is backward compatible, provided the System 80 ROM code is installed at U2 and U3. If used on a game with the 1st generation CPU, the game code must be doubled up on a 2716 EPROM, and installed at the PROM 1 position. This board is forward compatible with System 80B, provided all of the above outlined modifications are performed. Out of all the System 80 CPU boards, this is the most compatible with System 80B, due to using the same base circuit board.
 

====5th Generation CPU Board (System 80B)====
[[File:GTB sys80B CPU.JPG|300px|thumb|left|System 80B CPU Board]]
The fifth generation CPU is used in all System 80B games, and is marked with the following:
*D 20869
Even though the base circuit board is identical to the fourth generation CPU board, it's being named the fifth generation board, due to all of the major changes. The U2 and U3 masked ROM and sockets have been replaced with a piggyback daughter board soldered via header pins mounted in the U3 position. The daughter board uses a 2764 EPROM. Most of the related display segment and digit chips are no longer populated. This is due to the single display board handling these functions on its own board. The missing chips once used for the displays are Z19, Z21, Z22, Z23, Z24, and Z25. Equally, jumpers have been placed where Z19 and Z21 once resided. The fifth generation CPU is backward compatible, after the daughter board has been removed, and the missing display chips populated. Note that there technically are two different 80B CPU boards - MA-774 and MA-1133. The only difference between these two boards is a cut trace on the component side and a long trace wire added on the solder side from the E3 jumper to pin 35 of TC1. This modification is done to increase the ROM size of PROM 2 from a 2716 to a 2732.
 
 
Any of the Gottlieb® System 80 / 80A / 80B CPU boards are compatible cross platform. It's just matter of how much work must be done to modify each board.
 

=====System 80B CPU Jumper Settings=====
[[File:GTB Sys80B Jumpers.jpg|300px|thumb|left|The location of jumpers discussed...]]
All System 80B games have the E1 and E2 jumpers installed. Jumpers E8, E9, E10, E11, E12 are unused in all games.

The first five System 80B games, Chicago Cubs, Bounty Hunter, Tag Team Pinball, Rock, and Rock Encore, use a single ROM at the daughterboard chip socket. Therefore, jumpers associated with PROM 2 connections may not be installed. If jumpers are installed, it doesn't matter what position(s) they are placed in.

For all games after the first five System 80B games and prior to the last five, jumpers E4, E5, and E7 should be installed.

For the last five System 80B games, Excalibur, Bad Girls, Big House, Hot Shots, and Bone Busters, jumpers E3, E5, and E7 should be installed. 
For Night Moves (made by International Concepts using the 80B board set), these same jumpers should be installed. 
 
Note: The last five System 80B games, along with Night Moves, used a 2732 PROM at the "PROM 1" position. The socket is marked PROM 1", but PROM 2 is inserted into this chip socket . Additional modifications to the PCB may be necessary. See [[Gottlieb_System_80#...using_an_MA-1133_or_MA-774_MPU_in_games_that_REQUIRE_a_2732 | "...using an MA-1133 or MA-774 MPU in games that require a 2732"]], for more information.
 

====U2/U3 ROM Part Numbers====
[[File:GottliebSystem80ROMs.jpg|300px|thumb|left|System 80 ROMs]] 
All Gottlieb System 80 U2/U3 ROMs will be labeled as pictured at left. 
U2 is labeled "R3273-12" on the center line. The top line is the part number, a 2332 ROM. The bottom line is the date code, in this case, the 15th week of 1981. 
U3 is labeled "R3272-12" on the center line. The top line is the part number, a 2332 ROM. The bottom line is the date code, in this case, the 12th week of 1981. 

[[File:GottliebSystem80AROMs.jpg|300px|thumb|left|System 80A ROMs]] 
Gottlieb System 80A ROMs may be labeled in a few different ways since Gottlieb used several manufacturers to provide the ROMs. A clear indication that the ROMs are for System 80A games is that somewhere in the labeling, "XO-326 U2" or "XO-327 U3" will be shown as pictured at left.
 

===Driver Board===

[[File:Gtb sys80 drvr pw.png|300px|thumb|left|The System 80A / 80B Driver Board]]
The System 80 Driver board is responsible for all controlled lamps, relays, and all solenoids in the game. The CPU controls the driver board operation via a simple interface between A1J4 on the CPU and A3J1 on the driver board. Although the driver board went through some minor changes over the years, the same board can be adapted for all of the System 80 platforms. 

To control the games' total of 52 '''lamp circuits''', the interface provides "device select" signals for each of the 74175s (Quad-D Flip-Flops) on the driver board, and 4 "bits" of data that is loaded (or "clocked") into a particular 74175 via the aforementioned device selects. Each lamp is driven discretely by a particular output of a particular 74175, which in turn drives an MPS-A13 or MPS-U45 transistor, (NDS-U45 transistors were used in place of MPS-U45s in some cases). Gottlieb® did not implement a "lamp matrix" as some other manufacturers did.
 

It is noteworthy that there are some dedicated lamp transistors, which control specific game relays across the System 80 / 80A platforms. Relays such as the game over, tilt, and coin lockout relays are controlled by Q1, Q2, and Q3 respectively. The tilt and game over relays use the same designation for the System 80B platform, however, the use of a coin lockout relay was abandoned by this time. One neat feature of the driver board circuitry is that lamp "n" is driven by transistor Q"n+1". i.e. L12 is driven by Q13. 

[[File:Gtb_sys80_drvr_board_coin_ctrs.JPG|300px|thumb|left|Driver Board with Coin Counter Transistors Highlighted ]] 
To control the games' '''solenoids circuits''', the driver board uses signals directly from the CPU to enable transistors on the driver board which turn on up to 9 solenoids. For solenoid control, the driver board uses MPS-U45, 2N3055, and 2N6043 transistors. Starting and ending with the System 80 platform, (games from Spiderman to Haunted House), three transistors were reserved to drive optional mechanical coin counters. These mechanical coin counter solenoids and associated transistors are: solenoid 3 (Q54), 4 (Q55), and 7 (Q56). Starting with the System 80A platform, (Devil's Dare), these transistors were no longer reserved for coin counters, and were used for other functions. Equally, the 3 diodes associated with these 3 transistors were changed to 3 zero ohm jumpers. 

The games' '''sound''' signals (S1, S2, S4, S8) also pass through the driver board at Z13, a 7404 Hex Inverter. See below for S16 and S32.
 

====Repurposed Driver Board Circuits====
[[File:Gtb under pf transistor.JPG‎|300px|thumb|left| A Typical Remote Transistor Mounted Under the Playfield]] 
Since quite a few System 80 games employ more than 9 solenoids, and since the original driver board design will drive a maximum of 9 solenoids, Gottlieb® repurposed some lamp outputs to drive "under-playfield transistors" which drive additional solenoids.
 

[[File:Gtb ma1011 trans board.JPG‎|300px|thumb|left| A Typical Transistor Driver Board]] 
Once playfields became littered with numerous "under-playfield transistors", Gottlieb® opted to merge some of these transistors into a transistor driver board. The transistor driver board started to appear on Gottlieb® games nearly midway through the System 80B platform, with the game Victory.
 

The sound S16 and S32 signals are also repurposed lamp outputs. For instance, Haunted House and Black Hole both repurpose L9 to S16. Robo-War repurposes lamp 4 to S16. Note that S16 is not consistently implemented across the System 80 family. Note also that references to the usage of S32 are difficult to find.
 

===Auxiliary Lamp Driver Boards===
[[File:Gtb aux lamp 5.JPG|300px|thumb|left| A Typical Aux. Lamp Driver Board Using MPS-U45 Transistors (Maximum Control of 10 Lamps]]
[[File:Gtb aux lamp MA866 2N6043.JPG|300px|thumb|right| A Typical Aux. Lamp Driver Board Using 2N6043 Transistors (Controls a Maximum of 20 Lamps]]
 
Starting with Time Line, several System 80/80A/80B platform games use auxiliary lamp driver boards. These boards are commonly referred to as "chaser boards" or "lamp chaser boards". The reason for either of these nicknames is because these boards are used to control lamps for effect. They are either placed in the backbox or under the playfield. With later System 80B games, they were located in the lower cabinet. Location is typically dependent upon what lamps are being controlled. The aux. lamp driver boards are not controlled by the CPU. The only signals needed for an aux. lamp driver board to function is +5V and ground. 

There are several different variants of auxiliary lamp driver boards used. The earliest versions use MPS-U45 transistors to control a maximum of three lamps per transistor. Both 15 and 30 lamp versions (5 or 10 transistors) of this board exist. Some later boards use NDS-U45 transistors instead of MPS-U45 transistors. It is assumed this is due to a the cost or lack of MPS-U45 transistors during production. Either of these style of boards are interchangeable with one another. Finally, there are some boards used in later games which use 2N6043 transistors. These are designed to control #67 flashlamps, but this is not always the case. This style board was used to control lamps also. These boards are equally compatible with previous designed boards, when used as a complete, drop-in replacement. However, MPS-U45, NDS-U45, and CEN-U45 transistors are not 1-to-1 compatible with 2N6043 transistors. A viable replacement transistor for the 2N6043 is the TIP102. 

The main difference between any of the auxiliary lamp boards is the amount of transistors used to drive lamps, and the resistor (R13) used to control the rate at which the lamps flash or "chase". Boards using 2N6043 transistors have different resistor values for resistors R2-R11 than boards which use MPS-U45s or NDS-U45s. A table of auxiliary lamp driver boards used on most games is shown below.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Game
!Part #
!Total Transistors
!Total Lamps Controlled
!R13 Resistor Value
!Controls
!Location
!Notes
|-
|Time Line|| ||10||?||820K Ohm||Chaser lamps behind nuclear symbol on backglass||In backbox||
|-
|Mars:God of War|| ||10||28||330K Ohm||Backglass perimeter chaser lamps||In backbox||1 of 2
|-
|Mars:God of War|| ||5||10 (LEDs)||330K Ohm||LEDs behind tube||Under PF||2 of 2
|-
|Volcano|| ||10||20||560K Ohm||Upper backglass perimeter chaser lamps and volcano effect behind backglass||In backbox||
|-
|Black Hole|| ||10||28||270K Ohm||Backglass perimeter chaser lamps||In backbox||
|-
|Haunted House||MA-234||10||21||270K Ohm||Behind backglass lightning effect lamps||In backbox||
|-
|Rocky|| ||10||19||560K Ohm||Behind backglass||In backbox||
|-
|Spirit|| ||10||20||Varies||Behind backglass||In backbox||
|-
|Tag Team Pinball|| ||10||20||820K Ohm||Multiball insert illumination||Under PF||
|-
|Rock|| ||10||18||680K Ohm||Extra ball insert path||Under PF||
|-
|Rock Encore|| ||10||18||680K Ohm||Extra ball insert path||Under PF||
|-
|Raven|| ||10||20||680K Ohm||Inserts leading to ramp||Under PF||
|-
|Hollywood Heat|| ||10||20||680K Ohm||Ramp insert illumination||Under PF||
|-
|Genesis|| ||10||10 (#67 Flashers)||680K Ohm||In top of backbox ||Under PF||Uses 2N6043
|-
|Genesis|| ||10||10 (#67 Flashers)||680K Ohm||Around playfield window ||Under PF||Uses 2N6043
|-
|Gold Wings|| ||10||8 (#67 Flashers)||680K Ohm||Flashers in topper ||Under PF||1 of 3
|-
|Gold Wings|| ||10||6 (#67 Flashers)||680K Ohm||Flashers in topper ||Under PF||2 of 3
|-
|Gold Wings|| ||10||10||680K Ohm||Inserts leading to ramp ||Under PF||3 of 3
|-
|Monte Carlo|| ||10||5||680K Ohm||Behind $10,000,000 sign||Under PF||1 of 2
|-
|Monte Carlo|| ||10||30||680K Ohm||Lamps around perimeter of topper||Under PF||2 of 2
|-
|Spring Break|| ||10||30||680K Ohm||In topper||Under PF||1 of 2; only if topper present?
|-
|Spring Break|| ||10||20||680K Ohm||Special shot and shooter loop||Under PF||2 of 2
|-
|Arena||MA-936||None||10 (LEDs)||560K Ohm||LED strip under shooter lane wireform ||Under PF||
|-
|Victory|| ||10||10 (#86 bulbs)||680K Ohm||Next to left ramp||Under PF||1 of 2
|-
|Victory|| ||10||10 (#86 bulbs)||680K Ohm||Next to right ramp||Under PF||2 of 2
|-
|Diamond Lady||MA-789||10||5||680K Ohm||Loop right of the ramp||Under PF||
|-
|Robo-War|| ||10||20||680K Ohm||Inserts in lower portion of playfield ||Lower cabinet||(1 of 2) Uses 2N6043
|-
|Robo-War|| ||10||10 ||680K Ohm||Under playfield glass stop||Lower cabinet||(2 of 2) Uses 2N6043
|-
|Bad Girls|| ||10||5||680K Ohm||Drop target illumination ||Lower cabinet||1 of 2
|-
|Bad Girls|| ||10||10 ||10M Ohm||Under playfield glass stop||Lower cabinet||2 of 2
|-
|Bone Busters||MA-789||10||12||680K Ohm||Playfield inserts ||Under PF||(1 of 2) Uses NSD-U45
|-
|Bone Busters||MA-866||10||20 (#67 flashers)||680K Ohm||Backbox lamp insert||In backbox||(2 of 2) Uses 2N6043
|-
|}
 

===Sound Boards===

Gottlieb® uses different sound boards throughout the course of all System 80 platforms. Several of the sound boards cross platforms too. Out of all of the sound boards used, there is really only about three base units total with variations made to each one. 

====Sounds Only Board====
[[Image:Gtb sys80 sound.JPG|300px|thumb|left|Gottlieb® System 80 Sound Board MA-55 (Sounds only)]] 
The first System 80 sound board is capable of sound only. Based on the 6503 CPU architecture, this sound board is very similar to the System 1 Multi-Mode sound board. However, there are a couple of differences between the two boards. First, the +12VDC is no longer rectifed on the sound board. The +12VDC power comes from the power supply. Secondly, the +5VDC is no longer regulated on the sound board. The System 80 sound receives +5VDC from the power supply also. Finally, the pin outs for the System 1 sound board and the System 80 sound board are completely different. Even though either board will plug into either platform, '''DO NOT PLUG A SYSTEM 1 SOUND BOARD INTO A SYSTEM 80 GAME AND VICE VERSA!!!''' If this is done, bad stuff will happen.

Unfortunately, there are two chips on this style of board which are very difficult to source. This sound board uses a 6503 CPU and 6530 RIOT chip with special embedded code. 6530 chips marked with R3016-11 are for this System 80 sound board. 6530 chips marked with a R3014-12 or R3014-13 are for the earlier System 1 sound board. The two chips are not cross-compatible since they each have different code embedded in them for each game system.

In addition to being used in early System 80 games, this sounds-only board was also used in the export versions of Black Hole, Volcano, and Devil's Dare.

If the sound board is missing or cannot be repaired, there are daughter boards and aftermarket boards available. A daughter board called the "[https://coinop.mally.eu/produkt.php?bestellnr=101647&details=1 MIOT adapter]" is a replacement for the 6530 chip for both System 1 and System 80 sounds boards, produced in Germany. Pascal Janin in France has made a replacement sound board for both the original 2nd generation sound boards, and combination System 1 2nd gen boards / System 80/80A sound boards. These boards can purchased directly from Pascal - [http://www.flippp.fr/pifx1.php 2nd gen sound] & [http://www.flippp.fr/pifx.php combination Sys1 / Sys80/80A sound] . Although Pascal does not have US distributors, [http://www.bigdaddy-enterprises.com/ProductPages/flippp.html Big Daddy Enterprises], sometimes has these sound boards available too.
 

Prototype Sounds Only Board as found in System 80 Hulk

Images below capture a factory original Sounds only board prototype, complete with cuts (on component side) and jumpers (on solder side). Note the sound ROM marking of "500", the game number assigned to the System 80 Hulk prototype (10 units built). Also note the "extra" 24 pin IC labeled 7681-5 in the center of the board. This IC is not present on production versions of this board. Just a guess, but since this board has a 6532 installed vs the production 6530 (40 pin IC), the 7681 appears to be ROM space to drive the sound program.

<center>
<gallery widths=450px heights=250px perrow=2 caption="System 80 Hulk Prototype Sound Only Board">
File:System80HulkSoundsOnlyBoardFront.jpg|<center>Component side. Note "cut" at pin 21 of the center 24 pin IC.</center>
File:System80HulkSoundsOnlyBoardBack.jpg|<center>Solder side. Note factory green jumpers.</center>
</gallery>
</center>
 

====Sound & Speech Board====
[[Image:Gtb sys80&a s&s.JPG|300px|thumb|left|Gottlieb® System 80 / 80A B-20887-2 Sound & Speech Board]]
[[File:GTB SS B-20887-3 Front.JPG|300px|thumb|right|Gottlieb® System 80 / 80A B-20887-3 Sound & Speech Board]]
Starting with Mars God of War, the second System 80 sound board has the capability of speech. Ironically, this board is commonly referred to as the "sound and speech board", and was brought over from the Gottlieb® video game division at the time. Fortunately, Gottlieb® chose the 6502 CPU architecture just like the CPU board. There is a 6532 RIOT used also. The downside to this board is the now rare LM379S amp and SC-01 phoneme speech chip are both difficult to acquire. 

There are approximately three renditions of this board. Each will be marked with [http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Different_Revisions_of_the_Sound_and_Speech_Boards B-20887-X]. The "X" denotes a suffix of 1, 2, or 3. If the board has [http://en.wikipedia.org/wiki/Wire_wrap wire wrap] or resistors added to the solder side of the board, do not assume that it is some sort of diabolical, weird hack. These were recommended upgrades either done by the factory or out in the field. With each higher revision number, less wire wrap and resistors are present on the solder side of the board. However, each board revision typically has some degree of wire wrap added to it. 

Schematics corresponding to the -1 revision of the board can be found in the Mars, God of War and Volcano manuals. Schematics corresponding to the -3 revision of the board can be found in the Black Hole and Haunted House manuals.
 

====Sound Only Board====
[[Image:Gtb sys80 sound MA483 pig.JPG|300px|thumb|left|Gottlieb® System 80 / 80A Sound Board w/ MA-483 Piggyback Board (replaces LM379S amp)]]
[[File:GTB 23172-1 Sound Amp Piggyback.JPG|300px|thumb|right|Gottlieb® MA-483 Piggyback Board]] 
To reduce costs, Gottlieb® abandoned the speech option, and went a step backwards with a board generating sounds only. In doing so, they used the same B-20887-3 base board as the most current sound and speech board. The SC-01 speech chip socket in addition to the 74xx TTL chips, one of the LM741 op amps, and discrete components associated with the speech circuit were not installed on the board. By the time this board was first used, the LM379S amp was too costly and difficult to source. The solution was to add a single-side, piggyback board (as shown in the picture) with a TDA2002 amplifier and other necessary components. 

If this board is used as a replacement in a game which uses a sound & speech power supply, (Haunted House for example), modifications to the s&s power supply must be made. This is due to the higher voltages necessary to operate the LM379S amp versus the TDA2002. If this board is installed in a game where the sound and speech board power supply was not modified, the guarantee of destroying the TDA2002 amp is inevitable.
 

[[Image:GottliebSystem80SoundMA483WithPigAndDip.jpg ‎|300px|thumb|left|Gottlieb® System 80 / 80A Sound Board w/ MA-483 Piggyback Board and DIP switch bank]] 
A slightly different variant of this board was used in Royal Flush Deluxe. This revision of the board included the 8 position DIP switch bank.
 

====Sound Only Board with Piggyback====
[[File:GottliebSystem80ABSoundsOnlyWithPiggyback.jpg ‎|300px|thumb|left|Gottlieb® System 80A / 80B Sound Board MA-490 w/ MA-488 Piggyback Board (Sounds only)]]
[[File:Gtb piggyback sound factory trace wire.JPG|300px|thumb|right|Gottlieb® System 80A / 80B Sound Board w/ Factory Trace Wire]]

To reduce costs even more, Gottlieb® started using a modified sound only board, which was first used with Spiderman in 1980. This "new" sound board was first used during the production of Amazon Hunt, and continued until Tag Team Pinball. The main modification of the board was the addition of a piggyback board. The piggyback board was used to increase the size of the sound ROM by using a 2716 EPROM. 

Two other noteworthy modifications are an added factory trace wire on the solder side of the board, and a cut trace between pin 8 of U7 (7404) and a header pin on the component side of the board. The added trace wire runs from pin 3 of U1 (6503 CPU) to pin 18 of U2 (piggyback header pins). Both of these modifications should remain intact for the board to function properly. 

It is also worth mentioning that this is one of the few instances where Gottlieb® used a double-sided piggyback board. The benefit of using a double-sided board is the decreased chance of cracked header pins, where the header pins attach to the underside of the piggyback board.
 

====System 80B Sound Board (two button)====
[[Image:GTB Sys80B Sound.JPG|300px|thumb|left|Gottlieb® System 80B MA-766 Sound Board]] 
And now for something completely different. Well, not really. The MA-766 sound board hit the scene with Rock, but a similar design was already used prior by the Gottlieb® video game division (Mylstar) when it existed. It is based on the 6502 CPU architecture, but uses two 6502s instead of one.

Two momentary push button switches are present on the board - SW1 and SW2. Upon pushing SW1, the sound board should output a single blip (tone). SW2 is used to manually reset the CPU on the sound board. A bank of 4 dipswitches is located adjacent to SW1. Dipswitches 1-3 should always be off, while dipswitch 4 should remain on for proper function.
 

====System 80B Sound Board (one button)====
[[Image:Gtb sys80b MA886 sound.JPG|300px|thumb|left|Gottlieb® System 80B MA-886 Sound Board]]
[[Image:GTBMA886SoundDepop.jpg|300px|thumb|right|Gottlieb® System 80B MA-886 Sound Board, only partially populated (found in Big House, Bad Girls, etc.]]
The MA-886 board is essentially the same as the previous sound board, except it uses 2 separate .156" header pin connections instead of edge connectors for inputs / outputs. Some other obvious changes are the omission of momentary test button SW1, the omission of the 4-bank dipswitch, the omission of YROM2 socket. In addition, a socket is sometimes populated at position S4 and neither AY-3-8913 orator chip is populated. Momentary test button SW2 is still preset, and is still used to manually reset the board's processor. The lack of YROM2 is because the MA-886 board allows for the use of larger EPROMs. The S4 socket has been added on some boards, and is used to transfer data via a ribbon cable to an auxiliary sound board (MA-1033 or MA-1294). These boards also stuff R58 with a 10K 1/4W resistor and may have JP8 cut or not stuffed.
 

=====Bone Busters Sound Board=====
[[Image:MA766-719A.jpg ‎|300px|thumb|left|Gottlieb® System 80B MA-886-719A Sound Board]]
The MA-886-719A sound board (also noted as MA-1299-719 in the manual) is an additional sound board found only in Bone Busters. It is based on the MA-886 sound board, but it is a stripped down version with much fewer populated components.
 

=====Amazon Hunt II Sound Board=====
[[Image:placeholder.jpg|300px|thumb|left|Gottlieb® System 80B MA-982 Sound Board]] 
The MA-982 sound board is used only in the conversion game: Amazon II. It is based on the MA-886 sound board, but it is a stripped down version with much fewer populated components.
 

====System 80B Auxiliary Sound Board====
There are two versions of the auxiliary sound board.

[[Image:MA1033AuxSound.jpg|300px|thumb|left|Gottlieb® System 80B MA-1033 Auxiliary Sound Board]] 
The MA-1033 auxiliary sound board was used in System 80B games including: Bad Girls, Big House, and Hot Shots, as well as one System 3 game: Lights, Camera, Action.
 

[[File:GTB Sys3 sound MA-1294.JPG|300px|thumb|left|Gottlieb® System 80B MA-1294 Auxiliary Sound Board]]
The MA-1294 auxiliary sound board was only used in one System 80B game, Bone Busters, as well as System 3 games including: Hoops, Bell Ringer, Silver Slugger, Car Hop, Deadly Weapon, Title Fight, and Vegas.
 

===Speakers===
[[File:Panthera Head Speaker.jpg|thumb|left|300px|Typical speaker located in the head of a System 80 game (Panthera)]] 
System 80 games use a dual speaker system. In most cases, (where there is a grill above the backglass), there is a 6-1/2", 8 ohm, low wattage speaker in the lower cabinet, and a second one in the head, behind the grill in the backbox. Some games, like Haunted House, have two speakers in the lower cabinet.
 

[[File:GTB-80a-the-games-speaker.jpg|thumb|left|300px|Single speaker from an 80A game (The Games)]] System 80A games may have two speakers or just one. Again, these are 6-1/2", 4 ohm, low wattage speakers.
 

[[File:GTB Tag Team Speaker.jpg|thumb|left|300px|Single speaker from an early 80B game (Tag Team)]] 
Early System 80B games, Chicago Cubs, Tag Team, and Bounty Hunter, all use a single 6-1/2" 4 ohm speaker in the lower cabinet.

Starting with Rock, 80Bs use a 6-1/4" in the cabinet and a small speaker on the left of the display panel. The last few 80B games, where the speaker panel is located above the translite, use three speakers total (2 above the translite and 1 in the lower cabinet).
 

===Displays===
====System 80====
[[Image:GottliebSixDigitDisplay.jpg|300px|thumb|left|Gottlieb® 6 Digit Display]]
[[Image:GTB 6 digit display back.JPG|300px|thumb|right|Gottlieb® 6 Digit Display (Back)]]

[[Image:GTB status display.JPG|300px|thumb|left|Gottlieb® 4 Digit Display]]
[[Image:GTB status display back.JPG|300px|thumb|right|Gottlieb® 4 Digit Display (Back)]]
 

=====Display Test - System 80=====
Display test is step number 19 System 80 games. Each display, including the credit/match display participates in "walking" each digit (0 through 9 beginning with 0) across each display. The "walking" begins at the match side of the credit/match display, then moves to players 1 and 3, then to players 2 and 4. After a "9" is walked through all displays, the cycle starts again with "0".
 

====System 80A====
[[Image:GTB 7 digit display.JPG|300px|thumb|left|Gottlieb® System 80A 7 Digit Display]]
[[Image:GTB 7 digit display back.JPG|300px|thumb|right|Gottlieb® System 80A 7 Digit Display (Back)]]
[[Image:GTB status display.JPG|300px|thumb|left|Gottlieb® 4 Digit Display]]
[[Image:GTB status display back.JPG|300px|thumb|right|Gottlieb® 4 Digit Display (Back)]]
 

=====Display Test - System 80A=====
Display test is step number 19 System 80A games. Each display lights every position, and advances through all of the numbers starting with "0" and ending with "9". Once "9" is reached, the process starts over at "0" again.
 

====System 80B====
[[File:System80BDisplayFront.jpg‎|300px|thumb|left|Gottlieb® System 80B MA-644 Display Component Side]]
[[File:System80BDisplayBack.jpg‎|300px|thumb|right|Gottlieb® System 80B MA-644 Display Solder Side]]
System 80B games introduced the 20 alphanumeric character dual line display module. These displays evolved over time. The one pictured here was used in games Chicago Cubs Triple Play until Excalibur. The two large ICs found on this board (Rockwell 10941 segment driver and Rockwell 10939 digit driver) are long obsolete and very hard to obtain. Other components on the board are readily available. 

The board rectifies 32VAC via diodes CR1-CR4 to produce -45VDC and -15VDC for use by the segment and digit drivers. Should one or more of these diodes fail, the foil trace on the board sometimes acts like a fuse, and burns itself up. The picture at right shows a board that experienced this failure, along with a jumper to repair the damaged trace.
 

[[FILE:GTB_80B_Large_AlphN_Display.JPG|300px|thumb|left|Gottlieb System 80B MA-999 Alpha-Numeric Display Board with header pin connections. (Bad Girls)]] 
The last System 80B games (Hot Shots, Big House, Bad Girls, and Bone Busters) all used a larger alphanumeric vacuum fluorescent display assembly. This type of display used two sets of .156" header pins instead of the more familiar edge connection. 
 

=====Display Test - System 80B=====
[[File:Gtb alphanum display test.gif|thumb|left|300px|Simulation of System 80B display test]] 
Display test is test number 20 for System 80B. All 40 of the alpha-numeric "digits" (both the top and bottom displays) will light starting with a "0", next a "+", then an "X", and finally a ",". In doing this, all possible segments of all the display digits are lit at one point during display test.
 

===Reset Board===
[[File:Gtb sys80 reset.JPG|thumb|left|300px|Gottlieb® System 80 / 80B MA-980 Reset Board]]
[[File:GTB Sys80B Newer Reset Board.jpg|thumb|right|300px|Gottlieb® System 80B MA-1143 Reset/Anti-Static Board]] 
Starting with Devil's Dare, the first System 80A game, the reset board became a staple of the Gottlieb® design to automatically reset the CPU board should the CPU lock up. Apparently games locking up on location was an issue with System 80 games. The reset board was created to resolve this issue, should the game lock up, and no one is present to manually reset the game by shutting it off and turning it back on. 

The MA-980 reset board is a small footprint PCB with the board designation of A24, and is located adjacent to the TC1 connector of the CPU board. The connection on the reset board is A24P1, while the connection for TC1 of the CPU board is A24P2. As long as someone can turn the game off, should it lock up, there is no need to keep the reset board connected. In most cases, the aged reset boards are more troublesome if allowed to remain connected.
 

[[File:GTBResetBoardConnector.jpg|thumb|left|300px|Connection at TC1 to the reset board.]]
[[File:GTB_RW_3K_Pullup.JPG|thumb|right|300px|A 3.0Kohm resistor, added between pins 7 and 11 of TC1.]] 
Along with adding the reset board, Gottlieb® added a 3.0Kohm resistor across pins 7 and 11 of the reset board connection at MPU connector TC1. If not using the reset board, it's advised to add this resistor to the back of the board, as shown at right. This resistor pulls the R/W (read/write) line high when not pulled down by the 6502.

If using connector A24-P2, do not add the 3.0Kohm resistor. Doing so will change the effective resistance to 1.5Kohms (value of resistors in parallel).

The reset board connector also has a 1N270 diode soldered to it. There is no need to add this diode to the MPU since it's part of the reset board function. 

More Regarding the 3Kohm Pullup Resistor 
Most MPU boards will work without the reset board but some MPU boards do refuse to work without the Read/Write pullup resistor.

The 3K resistor was added for two reasons:

#It provides a stable Read/Write signal at power-up. There is a tiny fraction of time at power up where data can be written into Z5 but due to gate Z36A, this data write is prevented. The resistor does provide a proper biasing to the Read/Write line at time of powerup.
#More importantly - A Rockwell 6502 has a minimum VOH of 2.4volts, a 4069 requires a minimum VIH of 4 volts.

In other words: 
*The Read/Write output from U1 (pin 34) guarantees the output will be 2.4 volts or higher for a logic 1. 
*The 4069 located at Z36D (pin 9 input of Z36) requires the input to be 4 volts or higher for a logic 1. 
*The 3K pullup resistor pulls the Z36D input closer to the required voltage range.

Do realize that even though this problem exists on all System 80/80A/80B boards but only a very small fraction of these Gottlieb boards exhibit any symptoms. The chances that you have one if these that exhibit symptoms is quite slim. 

==Problems and Solutions==
===Initial Troubleshooting===
When attempting to troubleshoot a malfunctioning or non-booting game, there are a few initial steps to perform before diving into more serious troubleshooting.

# If the MPU has damage from a leaking battery, it will need to be addressed.
# Clean off all the edge connector contacts using a pink rubber eraser. This will remove any tarnish or grime that has built up over the years. Do not use sandpaper or fiberglass erasers on the contacts--they will only thin the material. There is a small risk that rubbing the eraser on the contacts will dislodge one of them, but this is very uncommon to see happen on system 80 boards.
# Check all the fuses using a multimeter in diode/continuity mode. Do not rely on a visual inspection. Sometimes a fuse will appear to be intact, but actually may be blown. Fuses are located near the transformer and on the underside of the playfield.
# Check voltages on the fuses near the transformer to make sure they are as expected.
# Check the power supply voltages and make sure that they are as expected. 5v may need to be adjusted to 5.03v to ensure that the MPU recieves the necessary power it needs in order to boot.
# Be sure to [[#Adding_Ground_and_5V_Connections_to_Interconnect_Harness|install the two jumper wires in the interconnect harness]] between the driver board and MPU.

These steps may help address a number of common issues before proceeding to some of the more specific problems that can occur with system 80 games.

===Connectors, Connectors, Connectors===
Connectors, connectors, connectors!!! Since the Gottlieb® System 80/80A/80B boardset primarily relies on Molex connectors to pass data and voltages from board to board, the connectors should be addressed first. Before even attempting to turn a Gottlieb® System 80/80A/80B game on for the first time, worn or corroded edge connector contacts must be replaced. Cleaning or burnishing connector contacts is not a viable option to ensure a game's reliability. 

Poor connector contacts are the number one reason why System 80/80A/80B games do not function properly. Poor or missing connector contacts have a cascading effect too. The end results of bad connector contacts can be, but are not limited to:

*voltages which mysteriously disappear and reappear
*increased resistance
*specific switches not functioning
*lamps locking on
*lamps not turning on
*displays not properly functioning
*coils not turning on
*coils locking on
*CPU boards not booting, booting sporadically, or randomly resetting
*driver boards not functioning or functioning sporadically

So, it is very important that the connector contacts are shiny, have proper spring tension, and are properly crimped for the over all reliability of the game. Random, flaky issues which happen either sporadically or all the time are attributed to poor connector contacts in nearly every case. 

<center>
<gallery widths=450px heights=100px perrow=2 caption="System 80 Connector (J6), The Good, The Bad, and The Ugly">
File:System80ConnectorBadPins.jpg|<center>An example of pins in desperate need of rehab.</center>
File:System80ConnectorGoodPins.jpg|<center>Ahhh...Much nicer after repinning.</center>
</gallery>
</center>
 

[[File:SandedGottliebEdgeConnector.jpg|300px|thumb|left|Sanded (or possibly bare from the factory) card edge contacts will corrode and degrade the electrical connection.]]
[[File: GottliebEdgeConnectorRehab.jpg|300px|thumb|right|The two connector pads on the left have been lightly scratched with the fiberglass pencil. Even the small bit of oxidation or corrosion shown on the remaining pins is enough to prevent a connection.]] 
A common (poor) practice is to sand the card edge contacts to the bare copper as shown at left. While this may alleviate issues in the short term, longer term the copper will oxidize and cause more problems. All copper oxidizes. Copper is beautiful on building rooftops when first installed but oxidizes to a light green patina over time. Card edge contacts will do the same thing.

If the card edge contacts aren't bright and shiny, they can be cleaned off with a pink rubber eraser or lightly scratched with a fiberglass pencil. This will remove oxidation and grime without harming or thinning the finger contacts. If the contacts are corroded (due to battery damage) or have divots in them, lightly sand them, then re-tin them with a thin coat of solder. Either suck the excess solder off with a solder sucker or when heated, wipe the solder off with a rag. Avoid heating the card edge contacts too much as they will detach from the PCB.
 

====Replacing (Repinning) System 80 Connectors====
Replacing connectors in a pinball machine somehow adopted the term repinning. Repinning a System 80 connector housing isn't too bad overall. On a difficulty scale of 1 to 10 (1 being the easiest to do) compared to all other makes and platforms made, System 80 connector replacement is about a 3. One benefit regarding the System 80 IDC housings is that they are reusable. Below are the steps to remove the connector from its housing. 

*First, grasp the housing in one hand. .
*Next, use the Molex tool pictured below by sliding it behind the pin to release the "barb" holding the pin in.
*Finally, pull gently but firmly on the wire.

Conversely, a small "pocket" flat blade screwdriver can be used to remove the Molex connector. After pushing the connector tab down, pull the wire out and downward a bit.

Sometimes the connector comes out, and sometimes the wire pops out of the connector. If the latter, use a small jeweler's screwdriver to gently pry the very end of the connector against the rectangular opening in the connector housing. You're trying to get the IDC "ears" of the connector to clear the housing. Sometimes the connector will easily come right out. If it doesn't, use small needle nose pliers with serrated jaws, to grab the "ear" of the connector, and pull it out.
 

[[File:Molex11-03-0016.jpg|300px|thumb|left|A Molex Contact Extraction Tool, Molex part number 11-03-0016]] 
Some system 80 connector housings are "double sided" edge connectors. All of the connector housings that are double sided are black from the factory (blue colored housings are typically Jamma connectors used as replacements, and do not apply to this section of this guide). To remove pins from these connector housings, you need a pricey yet effective tool called a Molex contact extraction tool, (commonly referred to as a Molex extractor). The Molex part number for the extractor is 11-03-0016, and can be purchased from [http://www.greatplainselectronics.com/search.asp?pg=1&stext=11-03-0016&sprice=&stype=&scat= Great Plains Electronics] or other electronics vendors. Slide the extractor behind the pin to release the "tang" that holds the pin in. Firmly grip the wire and pull the pin out of the connector.

[[File:YT.png]] A YouTube video of the repinning process can be found [https://www.youtube.com/watch?v=hErTlsFOMw4&t=5s here].
 

====Alternate Method of Replacing (Repinning) System 80 Connectors====
[[File:AlternateRepin1.jpg|300px|thumb|left|The repinning on a single sided connector]]
[[File:AlternateRepin2.jpg|300px|thumb|right|The repinning on a double sided connector]]
Some System 80 (and most System 1) connectors do not have the slot for depressing the pin ear. Most guides (as in the previous section) recommend purchasing a somewhat pricey tool to insert into the connector and depress the ear. This procedure is tedious and takes a bit of practice. If you have a decently equipped shop which includes a drill press, repinning these connectors using the following steps might be easier for you. Using this procedure, you can expect to replace each pin in less then a minute. I repinned an entire A1-J4 / A3-J1 harness in about 40 mins. 

The procedure is to drill out the depression ear and pull out the pin:

* Install a 1/16" bit in your drill.
* Set up a jig by clamping a straight edge to your drill press table. Set the jig so the hole will be 1/4" from the edge of the connector.
* Drill through the plastic housing on the back/bottom side.
* When you feel resistance from the metal pin, gently continue to drill until you feel and hear it destroy the pin ear.
* Repeat for the remaining pins.
* Gently pull wire by hand and it will come out very easily. Pliers shouldn't be required.

The newly installed pins ears will correctly lock in place regardless of the holes.
 

===The CPU / Driver Board Interconnect Harness===
[[File:Gtb sys80 harn2.JPG|300px|thumb|left|The A1-J4 / A3-J1 Interconnect Harness]]
[[File:Gtb sys80 harn1.JPG|300px|thumb|right|The A1-J4 / A3-J1 Interconnect Harness]] 
There are 33 discrete signals which pass from the CPU board to the driver board via this connection. Two of the connectors pass ground and +5v logic to the driver board [http://pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Adding_Ground_and_5V_Connections_to_Interconnect_Harness (two more can be added)]. The remaining signals are for lamp, solenoid, relay and sound control. It is '''extremely important''' to have solid connectors installed in the CPU / driver board interconnect harness. Without decent connections, lamps, coils, relays, and sound can either lock on or not turn on at all.
 

====Adding Ground and 5V Connections to Interconnect Harness====
Yet one more power/ground update to make is to "double up" the 5VDC and ground connections between the MPU and the driver board. The OEM harness contains only one connection between the MPU and driver board for 5VDC and one connection for logic ground. This is an easy upgrade since spare connection positions are available in the connectors that lead to the correct edge contacts on each board. Approximately 8 inches of wire and four bifurcated crimp on pins (bifurcated style, Molex 4366 series, Product Family KK, product ID: 08-03-0304 at [http://www.greatplainselectronics.com/search.asp?pg=1&stext=4366&sprice=&stype=&scat= Great Plains Electronics]) are needed. 

Crimp a pin to each end of each wire. The connectors at each end should face opposite directions. Doing this will avoid twisting the wire as you insert the pins into the connector housing. In the picture below, the red wire carries 5VDC, blue wire carries logic ground. These colors were chosen for illustrative purposes only. Any color wire will do, of course.
<center>
<gallery widths=300px heights=200px perrow=3 caption="MPU-to-Driver Board Harness Upgrade">
File:S80HarnessUpgradeWires.jpg|<center>Pins crimped to extra wires.</center>
File:S80HarnessSlots.jpg|<center>Spare pin positions in harness.</center>
File:S80HarnessUpgraded.jpg|<center>5VDC and ground upgraded.</center>
</gallery>
</center>
 

===Ground updates===

==== Recommended Ground Improvements for System 80/80A/80B Boards ====

When the Gottlieb® System 80 board set was designed, for whatever reason, the designers did not physically attach each board to a common ground plane via a conductive back panel, standoffs and screws as Bally and Williams did. Instead, Gottlieb® relied on connectors and wires between each board to create a common ground. A poor connection due to dirty/damaged/fatigued connector pins will sever the ground between system components resulting in all sorts of odd behavior. 

To address this problem, it is important to examine each connector to ensure each pin is clean, and making solid contact with the card edge conductor. The ultimate (and recommended) insurance is to add an additional wire from each board's ground to a common ground point. Historically, the recommended location to join separate board grounds is at the power supply. That ground is then connected to the ground strip or transformer assembly in the cabinet bottom. 

These ground upgrades were initially recommended and published on the Internet by [http://flippers.com/gottlieb_ground_cures.html#System80 John Robertson of John's Jukes].

<center>
<gallery widths=200px heights=200px perrow=4 caption="Recommended Board Ground Wire Locations">
File:GTB_Sys80_PSU_Ground.jpg|<center>System 80/80A Power Supply</center>
File:System80bPowerSupplyGroundMod.jpg|<center>System 80B 5V Power Supply</center>
File:System80BAuxiliaryPowerSupplyCardEdge.jpg|<center>System 80B Auxiliary Power Supply</center>
File:Gtb sys80a cpu brd grd.JPG|<center>MPU Board</center>
File:Gtb sys80ab drvr brd grd.JPG|<center>Driver Board</center>
File:Gtb sys80 sound added ground.JPG|<center>System 80 Sound Only Board</center>
File:GTB Sound Speech ground Upgrade.JPG|<center>Sound and Speech Board</center>
File:GTB Sound Speech power sup ground Upgrade.JPG|<center>Sound and Speech Power Supply</center>
File:Gtb piggyback sound ground add.JPG|<center>System 80A/80B Sound Only Board</center>
File:GottliebSoundBoardGroundMod.jpg|<center>System 80B Sound Board (edge connector)</center>
File:S80SoundBoardHeaderGrounds.jpg|<center>System 80B Sound Board (header connector)</center>
File:GTB Aux Board Ground Upgrade.JPG|<center>Chaser Lamp Board</center>
</gallery>
</center>

Another design decision was to provide separate ground wires for groups of lamps and coils on the driver board. There are several variations used to tie the driver board lamp and solenoid discrete ground wires to the ground plane. The most common method Gottlieb® used was passing the ground wires through a large, inline Molex connector. If a group of lamps and/or coils are not working, there is a significant probability that a ground is missing. 

[[File:S80GroundsTiedTogether.jpg|left|thumb|300px|Tying all board ground together at a single point, on a System 80 or 80A game.]]
[[File:Sys80B_BoardGrounds_Added.jpg|right|thumb|300px|Using the 5VDC power supply heatsink as a tie point to add ground mods to a "non-foil" back panel game.]] 
Once all of the board grounds have been installed, tie them all together to a single point, as shown at left on a Gottlieb System 80 or 80A game. Here, one of the screws on the power supply is a handy attach point. Note that the coating on the cold plate at that screw point should be sanded bare, as discussed in step 9 of this [http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Recommended_Updates_and_Repairs_for_the_System_80.2F80A_Power_Supply_Board procedure]. 

For 80B games with "non-foil" back panels, one method is to use the +5V power supply heatsink as a tie point. Run a lead from the heatsink to the lower right bolt in the backbox. This bolt will have the factory ground straps secured to it. Make sure to sand or use a Dremel to remove the anodized coating from the heatsink where the grounds will be connected. This implementation eases subsequent board removal as fewer "eyelets" are involved to remove a specific board.

The other method, and a good alternative for 80B games with the "foil" back panel where the heat sink is isolated from the back panel with nylon dual sided washers, is to use wires long enough to tie each board to the lower right bolt in the backbox.
 

[[File:S80GroundTiedToCabinetGround.jpg|left|thumb|300px|Connecting all the grounds to cabinet ground (green/yellow wire).]] 
With the grounds all tied together at the power supply, tie that ground to the ground strip in the cabinet bottom. In the picture at left, the wire joined to all other grounds at the power supply is tied to a cabinet ground point (in this case the speaker housing). Cabinet ground points generally have a green wire with yellow tracer attached.
 

[[File:System80GroundStrap.jpg|left|thumb|300px|System 80 Cabinet Bottom Ground Strip]] 
The bottom board ground strap is where all grounds should come together for System 80 games.
 

=====Grounds Improvements for System 80A at Transformer Panel=====
[[File:Placeholder.jpg|300px|thumb|left|System 80A Grounds Cabinet Bottom Ground Strip]]
 

[[File:GTB Grounds Alien Star After.jpg|300px|thumb|left|Grounds at Transformer Panel (Alien Star)]] 
Gottlieb® did secure the grounds correctly on one particular game. As seen in the adjacent pic, the grounds on Alien Star were attached discretely on the transformer panel. These ground lines did not pass through a Molex connector like games before or games after. Why Gottlieb® did not continue this practice is unknown.
 

====Recommended Ground Improvements for System 80B====

=====Ground Improvements for System 80A / 80B at the Transformer Panel - "The Games" to "Bounty Hunter"=====
After Alien Star, Gottlieb® either soldered wire leads directly to the male spade connector board on the transformer panel (games like Chicago Cubs), or used female spade connectors (games like The Games, Touchdown, and Ice Fever), and used square, inline 9-pin Molex connectors to connect to the wiring harness. These connections, if the pins in the connectors are in good shape, are solid and do not require upgrade or modification.

<center>
<gallery widths=300px heights=300px>
File:Gottlieb-touchdown-transformer-panel.jpg|Grounds at Transformer Panel (Touchdown)
File:GTB Grounds Cubs.jpg|Grounds at Transformer Panel (Chicago Cubs Triple Play)
</gallery>
</center>
 

=====Ground Improvements for System 80B at the Transformer Panel - "Tag Team Pinball" to "Spring Break"=====
Ground connections used on System 80B games from Rock to Spring Break are the most unreliable style of ground connections Gottlieb® ever used. These connections consist of two (sometimes three) small boards each with two gangs of 9-pin male connections. The boards are fastened to the left side of the transformer panel's metal chassis. One problem with this is that the 9-pin female connection becomes loose, and in turn, ground connections become intermittent. Another problem is the male pins on the boards suffer from cracked solder connections. 

One common symptom of poor ground connections is multiple solenoids not functioning. If removing the 9-pin Molex plug from the ground board, rotating it 90 degrees, and reconnecting it causes non-working solenoids to function, the ground connections are bad. Whether or not this test proves that the ground connections are bad, it is highly recommended to improve the ground connections for future reliability. 

The purpose of these changes is to remove one potentially failed connection out of the equation. The grounds will then be secured directly to the transformer chassis via solderless eyelet crimp connectors. 

These ground upgrades were initially recommended and published on the Internet by [http://www.flippers.com/gottlieb_ground_cures.html#System3 John Robertson of John's Jukes]. Below are the steps to properly upgrade the grounds. 

<center>
<gallery widths=300px heights=100px perrow=3 caption="Gottlieb® System 80B Ground Upgrades (Tag Team Pinball to Spring Break)">
File:Gtb_sys80b_trans_ground_01.JPG|<center>The stock ground connections plugged into the ground connection boards on the left side of the transformer panel. This pic is a view from the left side.</center>

File:Gtb sys80b trans ground 02.JPG|<center>Remove all connections from the transformer panel. Then, unscrew the four 5/16" hex head screws which secure the transformer panel from the bottom of the cabinet. Turn the transformer panel on its side. This will allow better access to secure the ring terminals to the side of the chassis.</center>

File:Gtb sys80b trans ground 03.JPG|<center>Cut all of the ground wires as close as possible to the 9-pin connection. Remove the two boards with the 9-pin male wafer connections. As can be seen in the pic, Gottlieb® did actually secure the discrete transformer panel grounds to the panel's chassis with a single, soldered eyelet connector.</center>

File:Gtb sys80b trans ground 04.JPG|<center>All the ground wires are to have their insulation stripped back longer than usual - approximately 3/4". Solderless ring terminals are crimped onto the ground wires. The connections used in this particular application are Motormite #85443. Motormite brand does not have to be used. This particular brand and part number are mentioned due to the difficulty in finding the correct connectors to use. Most common ring terminals have a #10 or larger screw eyelet, which will not work effectively, if the eyelets are fastened to the side of the transformer panel chassis. The ring terminals shown here are made for #12-#10 gauge wire with an eyelet for a #8 screw. </center>

File:Sys80B Ground Transformer 02.jpg|<center>The ground Molex plugs and connection boards which were formerly fastened to the transformer panel's metal chassis. The four ground connector plugs (some games only use three total) were cut off from the incoming ground wires.</center>

File:Gtb sys80b trans ground 06.JPG|<center>Keep wires which were common to one connector together (driver board ground wires, playfield ground wires, and backbox ground wires). In doing this, future disassembly will be possible, should any of the individual wiring harnesses need attention or the playfield removed from the game. The ground wires are then twisted together and crimped. From experience, a maximum of 4 larger gauge wires can be crimped in one connection. Lighter gauge wires can be paired with or without heavier gauge wires. When doing this, the maximum effective grouping of wires increases slightly.</center>

File:Sys80B Ground Transformer 01.jpg|<center>The screws which were removed from the ground bus board should be reused to secure the eyelets to the transformer panel.</center>

File:Sys80B Ground Transformer 03.jpg|<center>The transformer is fastened to the bottom of the cabinet with the ground upgrades in place.</center>

File:Gtb sys80b trans ground last.JPG|<center>Pay close attention when securing the transformer panel to the cabinet. All four mounting screws typically have flat ground straps with an eyelet. These eyelet connections *must* be secured to the transformer panel. Otherwise, the earth grounds will not all be tied together anymore. Two of these ground connections are circled in the pic. There are two more located on the backside of the transformer panel.</center>
</gallery>
</center>

Although somewhat equally difficult to locate, an alternate to the Motormite # 85443 connectors are Tyco / AMP 408-2049-4 connectors. Again, any brand can be used, but make certain the eyelet hole is for a #8 screw (not a #10 or larger), and the crimp connector can accommodate #10 / #12 gauge wires (typically yellow insulation on crimp).

 

=====Ground Improvements for System 80B at the Transformer Panel - "Arena" to "Bone Busters" =====

Ground connections used on System 80B games from Arena to Bone Busters are the not as bad as the previous design, however, they are still unreliable at times. These connections consist of two small boards with three 10-pin .156" inline male header connections. The boards are fastened to the left side (or back side on newer games like Hot Shots) of the transformer panel's metal chassis. One problem with this is that the header pins get cracked solder joints, and in turn, ground connections become intermittent. 

One common symptom of poor ground connections is multiple solenoids not functioning. If removing the 10-pin Molex plug from the ground board, and reconnecting it at a different header causes non-working solenoids to function, the ground connections are bad. Whether or not this test proves that the ground connections are bad, it is highly recommended to improve the ground connections for future reliability. 

The purpose of these changes is to remove one potentially failed connection out of the equation. The grounds will then be secured directly to the transformer chassis via solderless eyelet crimp connectors. 

Like the previous section, these ground upgrades were initially recommended and published on the Internet by [http://www.flippers.com/gottlieb_ground_cures.html#System3 John Robertson of John's Jukes]. Below are the steps to properly upgrade the grounds. 

<center>
<gallery widths=300px heights=100px perrow=3 caption="Gottlieb® System 80B Ground Upgrades (Arena to Bone Busters)">
File:GTB 80B Victory Grounds 01.jpg|<center>The stock ground connections plugged into the ground connection boards on the left side of the transformer panel. This pic is a view from the left side.</center>

File:GTB 80B Victory Grounds 02.jpg|<center>Remove all connections from the transformer panel. Then, unscrew the four 5/16" hex head screws which secure the transformer panel from the bottom of the cabinet. Turn the transformer panel on its side. This will allow better access to secure the ring terminals to the side of the chassis.</center>

File:GTB 80B Victory Grounds 03.jpg|<center>Cut all of the ground wires as close as possible to the 10-pin housing. Remove the two boards with the three .156" 10-pin male header connections.</center>

File:GTB 80B Victory Grounds 04.jpg|<center>All of the ground wires are to have their insulation stripped back longer than usual - approximately 3/4". Solderless ring terminals are crimped onto the ground wires. The connections used in this particular application are Motormite #85443. Motormite brand does not have to be used. This particular brand and part number are mentioned due to the difficulty in finding the correct connectors to use. Most common ring terminals have a #10 or larger screw eyelet, which will not work effectively, if the eyelets are fastened to the side of the transformer panel chassis. The ring terminals shown here are made for #12-#10 gauge wire with an eyelet for a #8 screw. </center>

File:GTB 80B Victory Grounds 05.jpg|<center>The ground Molex plugs and connection boards which were formerly fastened to the transformer panel's metal chassis. The five ground connector plugs were cut off from the incoming ground wires.</center>

File:GTB 80B Victory Grounds 06.jpg|<center>Keep wires which were common to one connector together (driver board ground wires, playfield ground wires, and backbox ground wires). In doing this, future disassembly will be possible, should any of the individual wiring harnesses need attention or the playfield removed from the game. The ground wires are then twisted together and crimped. From experience, a maximum of 4 larger gauge wires can be crimped in one connection. Lighter gauge wires can be paired with or without heavier gauge wires. When doing this, the maximum effective grouping of wires increases slightly.</center>

File:GTB 80B Victory Grounds 07.jpg|<center>The screws which were removed from the ground bus board should be reused to secure the eyelets to the transformer panel.</center>

File:GTB 80B Victory Grounds 08.jpg|<center>The transformer is fastened to the bottom of the cabinet with the ground upgrades in place.</center>

File:GTB 80B Victory Grounds 09.jpg|<center>Pay close attention when securing the transformer panel to the cabinet. The four mounting screws may have flat ground straps with an eyelet. These eyelet connections *must* be secured to the transformer panel. Otherwise, the earth grounds will not all be tied together anymore.</center>
</gallery>
</center>

Although somewhat equally difficult to locate, an alternate to the Motormite # 85443 connectors are Tyco / AMP 408-2049-4 connectors. Again, any brand can be used, but make certain the eyelet hole is for a #8 screw (not a #10 or larger), and the crimp connector can accommodate #10 / #12 gauge wires (typically yellow insulation on crimp).

 

===Power Problems===
====Replacing the Orange Filtering Capacitor====
[[File:AgedOrangeCap.jpg|300px|thumb|left|A worn out original 6800uf/25V Gottlieb® filter capacitor]] 
If your System 80 or early System 80A game still has the original, orange 12VDC filtering capacitor in the cabinet bottom, it should be replaced. It's 30+ years old, has served the game well for a long time, and deserves a rest. Replace it with a new capacitor, valued from 6800uf to 12,000uf and at least 25V. Don't forget to acquire the right sized bracket to secure the cap to the bottom board.

A very nice replacement for this capacitor, specified at 12,000uf, can be found [http://www.greatplainselectronics.com/Category-67.asp here].

This capacitor filters the rectified 12VDC which is supplied to the power supply board for regulation down to 5VDC which is used by the every board in the game, including the MPU. Solid 5VDC power is critical for the game to operate properly. Hence the need for a properly working cap.
 

====Sporadic / Inconsistent / Missing Voltages====
[[File:GTB Sys80 PS Cold Joints.jpg|300px|thumb|left|This header pin was removed from the board by wiggling it loose!]] 
One problem with the System 80 power supply sporadic, inconsistent, or missing voltages. The game may be fine one minute, while the next minute, it loses voltage(s) completely. One of the main culprits for this is cracked header joints. Between vibration and the heat dissipated by the heat sink, header joints have a fairly high failure rate on System 80 power supplies. The fix is to disassemble the power supply (as seen in the next section), and replace the stock round header pins with square headers. 

====Recommended Updates and Repairs for the System 80/80A Power Supply Board====
[[File:GottliebSystem80PSBurnedCR7.jpg|300px|thumb|right|If CR7 on the Gottlieb power supply looks like this, the board should be rehabbed immediately.]] 
The System 80 Power Supply board is a pretty tough bugger. Still, after years of steady operation, they do fail, and they require refurbishment / rebuild. 
The test point values are silk screened on the System 80 power supply board. They are +5VDC, +8VDC, +42VDC, and +60VDC. Ground, or "common" is also labeled. 
Given that the parts to refurbish the power supply are cheap and readily available, and that taking the power supply apart is a bit of a pain, a good strategy is to replace all failure prone parts, whether the parts have failed or not, to avoid disassembling the power supply more than once. 

Mandatory parts list:
#.156 male header pins without friction lock, 9-pin, 7-pin, 6-pin, or break to size.
#500 ohm resistor cermet trimmer potentiometer. A quality sealed one like the one pictured is advised.
#3 inches of 18 gauge wire
#680 ohm 1/2 watt resistor (470, 510, 560, or 620 works also) replacement for R10, originally a 30 ohm 2W resistor and must be replaced if CR7 is replaced with a 1N4738 (below)
#1N4738 8.2V 1 watt zener diode (CR7, originally a 1N3445 8.2V 2W zener)
#12K ohm, 1/2 watt resistor (R3)

Optional parts list:
#1N4746 18V 1 watt zener diode (CR6, optional)
#47uf, 100V axial capacitor (C2, optional)
#LM723 voltage regulator and 14-pin socket (IC1, optional if the 5V section is operational)
#2N6057, 2N6059, or 2N6284 Darlington transistor (Q3, optional if the 5V section is operational)
#heat sink compound (optional as required)
#TO-3 mica insulator or heat sink gasket (optional as required)
#TO-3 transistor spacer (optional as required) Keystone 4616 or Mouser Electronics 534-4616
#2N5550 or 2N5551 transistor (Q2, optional)
#470uf/100V axial capacitor (C1, optional if the 42v/60v section is operational, this cap is often the cause of the 1/4A HV fuse blowing)
#TIP31C TO-220 NPN transistor (Q1, optional if the 42v/60v section is operational)
#TO-220 mica insulator (optional as required)
#TO-220 Passive Heatsink - Aavid Thermalloy 563002B00000G (only necessary if the existing heatsink is damaged or missing the PCB mounting tabs)
#TO-220 Nylon Bushing Insulator (only necessary if missing or damaged)
#Green LEDs (optional...use to identify that the board has been rebuilt)

Procedure:
#Remove the 4 screws that fasten the PCB to the cold plate (heat sink).
#Remove the 2 screws that fasten the back mounted transistor Q3 to the PCB and cold plate.
#Use a solder removal tool to remove the solder from the legs of Q3 that extend through the PCB. This is the toughest part of the job. If the board had been really hacked, two irons and a friend may be needed to accomplish this.
#Once the cold plate and Q3 have been removed, set those parts to the side.
#Replace parts on the PCB as recommended and advised by the particular failure.
#On the solder side of the PCB, solder a 3" wire from the ground trace to the screw mount, as shown in the picture below.
#When replacing the original round header pins with new square header pins, the through holes may require slight enlargement using a pick as shown in the picture below. Alternatively, the holes can be drilled with a small bit from the solder side of the board. Pressing the pins into the through holes without enlarging them might cause the solder pad to pop off the board. Key pins must be removed prior to installation as the PCB has no holes at the key pin position.
#Recheck all of the work performed.
#Sand the black insulating coating from the top/right screw hole on the front of the cold plate, as shown in the picture below. The insulating coating is very tough. A drum sander attachment on a Dremel works very well for this. To ensure enough has been sanded, use a meter to "buzz" between screw holes. The screw hole will be used later to tie the ground from each PCB together.
#Install Q3 (note that it will only install one way) onto the cold plate using the transistor spacer, mica insulator, and heat sink compound.
#Mate the two halves of the power supply together and reinstall the two screws which secure Q3.
#Solder the leads of Q3 to it's through-holes.
#To ensure continuity at each leg's solder joint, "buzz" the connection between the left leg of Q3 and the top leg of R9.
#Also "buzz" the connection between the right leg of Q3 and the bottom leg of R11.
#Install the remaining 4 screws around the perimeter of the power supply board.
#Lastly, ensure there is NO continuity between Q3 and the cold plate, as shown in the picture below. This is an essential step to ensure proper operation.

<center>
<gallery widths=170px heights=100px perrow=3 caption="System 80/80A Power Supply Repair">
File:Parts.jpg|<center>Parts Required</center>
File:PartsRemoved.jpg|<center>Front Side, Parts Removed and Board Cleaned Up</center>
File:PartsRemovedBack.jpg|<center>Back Side, Parts Removed</center>
File:EnlargingHoles.jpg|<center>Enlarging Header Pin Holes</center>
File:PartsReplaced.jpg|<center>Parts Replaced, Front Side</center>
File:PartsReplacedBack.jpg|<center>Parts Replaced and Ground Updated, Back Side</center>
File:R10ThermalStrainRelief.jpg|<center>Strain Relief for R10</center>
File:Sys80PSAllDone.jpg|<center>All Done</center>
File:Transistor-to-ColdPlateContinuityTest.jpg|<center>Ensuring no continuity between Q3 and the cold plate</center>
</gallery>
</center>

Once fully assembled, reinstall the power supply into the game. Connect ONLY J1 (the lower 9-pin connector) at this time. Power the game on, looking for the two LEDs to light. If they do not light, there will be rework to perform. Assuming that they do light, test each of the voltages that the power supply creates to ensure the correct power is being generated/regulated. Since the power is not "under load", each of the voltages may read 10% or so high. While measuring the 5V test point, adjust the 5V trim pot to about 5.1VDC. 

That's it! Done. 
Note: once the other boards are connected to the power supply, the 5V may sag some. Measure the 5V across the electrolytic cap just to the right of the MPU power connector. Using the 5V trim pot, adjust the 5V power to between 5.0 and 5.1VDC.

====Recommended Repairs for the System 80B Power Supply Board====
[[File:Gtb sys80b psu.JPG|300px|thumb|left|System 80B +5 VDC Power Supply. The adjustment POT is at the top of the PCB.]] 
Step one to improving power supply reliability is to replace the original 500 ohm 1 watt adjustment pot. This procedure can be done easily without removing the large heat sink. A replacement sealed pot is recommended, but not completely necessary.

Next, remove all the old solder from the all of the .156" header pins, and reflow new solder onto the joints. The top header pins (J2) supply +5VDC to the majority of the associated circuit boards in the back box. Provided that the power supply is delivering acceptable voltages in the +5VDC range, these two relatively simple repairs are the only things needed for this board.

However, if you've adjusted the pot as much as possible in the appropriate direction, and the power supply is still delivering voltages higher or lower than around +5VDC, it's probably time to look at replacing the LM338K voltage regulator. While not a frequent occurrence, the voltage regulator will sometimes fail.

If the voltages measured are less than 1VDC, the grounds for the power supply (located at the transformer panel) will more than likely need attention. Once the grounds at the transformer panel are better secured, recheck the voltage at the power supply.

Note: When measuring the +5VDC provided by the power supply, first disconnect J2 on the power supply. Measure power at the J2 male headers first. Once within an acceptable range, turn power off and reconnect J2. Measure power across C1, the 100uf/10V capacitor that is next to J1 (power connector) on the MPU. The MPU may drag the +5VDC supply down a bit. If you find this to be the case, adjust the trim pot on the power supply until a steady +5VDC is seen at the MPU. Poor connections between the +5VDC power supply and the MPU board may also reduce the voltage measured at the MPU.
 

====Optional Bling...Adding Power Indicating LED's to Boards====
=====CPU Board LED=====
How to add a "+5 volt" indicator for the Gottlieb System 80 Generation 1 CPU board (the D102 board). This will light up when + 5 volts are present on the CPU board.

'''Materials needed:'''

*1 Red LED, Jameco # 2125309 or Radio Shack # 276-209 or 1 Green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
*1 Resistor, 330 ohms, quarter watt, Radio Shack # 271-1315

#Drill two 1/16" diameter holes spaced about 3mm apart in the spot indicated just below power connector J1. This area has no traces to interfere with drilling.
#Install LED into board with flat side facing toward the power connector J1.
#Bend the flat side's lead to the negative (ground) point shown in the picture and solder it.
#The other lead of the LED will connect to one side of the 330 ohm resistor. The other end of the resistor will be soldered to the positive trace shown in the picture. You're done.

Now whenever the machine is powered on, this LED will indicate that the CPU board is receiving +5 volts from the power supply.

[[File:Sys80CPULEDholesfront.JPG|300px|thumb|left|Holes drilled on front of board]]
[[File:Sys80CPULEDholesrear.JPG|300px|thumb|right|Holes drilled on rear of board]] 
Circled areas are where to drill the two holes for the LED. Any color of LED can be used, but red or green are preferred.
 

[[File:Sys80CPULEDwiring.JPG|300px|thumb|left|Wiring on solder side of board]]
[[File:Sys80CPULEDfront.JPG|300px|thumb|right|LED installed on board]] 
Wiring of the resistor and LED. Note the location of the flat side of the LED.

 

[[File:Sys80CPULEDlitup.JPG|300px|thumb|left|Finished installation of LED]] 
Completed installation with LED lit up indicating the +5 volts is present on the CPU board.

 

=====Driver Board LED=====
Adding a "+5 volt" indicator to the System 80 Driver Board.

'''Materials needed:'''

*1 Red LED, Jameco # 2125309 or Radio Shack # 276-209 or 1 Green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
*1 Resistor, 330 ohm quarter watt, Radio Shack # 271-1315

#Drill two 1/16" holes spaced about 3mm apart in the board at the location shown in the pictures to the left of the electrolytic capacitor near chip Z1. There should be no traces at that area.
#Install the red LED with the flat side facing the trace going to the negative side of the electrolytic capacitor. Bend the LED's flat side lead down to that trace and scrape away some of the green paint at the point you will be soldering it. Now solder that lead to the trace.
#Solder one end of the 330 ohm resistor to the other lead of the LED.
#The other end of the resistor will now get soldered to the trace that goes to the positive side of the electrolytic capacitor. Again, be sure to scrape some of the green paint off of the trace where the resistor lead will be soldered. You are done.

Now whenever the machine is on, the LED will be lit indicating that the driver board is receiving +5 volts from the CPU board.

[[File:Sys80LED_holesfront.JPG|300px|thumb|left|Drilled holes on front of board]]
[[File:Sys80LEDholesrear.JPG|300px|thumb|right|Drilled holes on the rear of board]] 
Views of the holes drilled for the LED looking from the front and rear of the System 80 driver board.

 

[[File:Sys80LEDrear.JPG|300px|thumb|left|Wiring of the LED and resistor]]
[[File:Sys80LEDflat.JPG|300px|thumb|right|Finished installation]] 
Wiring of the resistor and LED. Notice the location of the flat side of the LED. Any color of LED can be used, but red or green is prefered.

 

[[File:Sys80LEDlitup.JPG|300px|thumb|left|Finished installation with LED lit]] 
Completed installation showing the LED lit up indicating +5v power is present on the driver board.

 

=====Pop Bumper Driver Board LED=====
How to add a "+5 volt" indicator for the Gottlieb System 80 Pop Bumper Driver Board. This will light up when + 5 volts are present on the board.

'''Materials needed:'''

*1 Red LED, Jameco # 2125309 or Radio Shack # 276-209 or 1 Green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
*1 Resistor, 330 ohms, quarter watt, Radio Shack # 271-1315

#From the solder side, mark and drill four 1/16" diameter holes spaced as shown in the spot indicated.
#Install LED into board with flat side facing toward the power connector J1.
#Bend the flat side's lead to the negative (ground) point shown in the picture and solder it.
#The other lead of the LED will connect to one side of the 330 ohm resistor.
#The other end of the resistor will be soldered to the positive trace shown in the picture.
#You're done.

Now whenever the machine is powered on, this LED will indicate that the CPU board is receiving +5 volts from the power supply.

<center>
<gallery widths=250px perrow=3>
File:gtb-sys80-pop-bumper-mod-led-supplies.jpg|Supplies needed.
File:gtb-sys80-pop-bumper-mod-led-1.jpg|Mark holes on solder side as shown.
File:gtb-sys80-pop-bumper-mod-led-2.jpg|Drill holes.
File:gtb-sys80-pop-bumper-mod-led-3.jpg|Stuff parts shown. Note the polarity of the LED.
File:gtb-sys80-pop-bumper-mod-led-4.jpg|Bend component legs as shown.
File:gtb-sys80-pop-bumper-mod-led-5.jpg|Solder all 3 connections as shown.
</gallery>
</center>
 

Repeat for each Pop Bumper Driver Board.

 

=====Auxiliary Lamp Driver Board LED=====
Adding a "+5 volt" LED indicator for the MA-234 auxiliary lamp driver board used in Black Hole and Haunted House.

'''Materials needed:'''

*1 Red or green LED, Jameco Electronics # 2125296 (9 cents each) or Radio Shack # 276-022 ($1.69 for a 2 pack)
*1 Resistor, 330 ohms, 1/4 watt

#Drill two 1/16" diameter holes about 3mm apart in the locations indicated in the pictures.
#Mount LED with the flat side toward the edge of the board.
#The lead from the LED's flat side will be soldered to pin 2 (ground) of connector A11P1. Be sure to slide a piece of heat shrink tubing over this lead so it does not accidently short to the other connector pins.
#The other lead of the LED will be soldered to one end of the 330 ohm resistor.
#The other end of the resistor will be soldered to pin 4 (+5 volts) of connector A11P1.

Whenever the machine is on, the LED should be lit, indicating the auxiliary lamp driver board is receiving power.

[[File:ALDLEDfrontholes.JPG|300px|thumb|left|Drilled holes on front of board]]
[[File:ALDLEDrearholes.JPG|300px|thumb|right|Drilled holes on rear of board]] 
View of the holes drilled for the LED as viewed from the front and rear of the board.

 

[[File:ALDLEDfront.JPG|300px|thumb|left|LED installed on board]]
[[File:ALDLEDrear.JPG|300px|thumb|right|Resistor and LED wiring]] 
Wiring of the resistor and LED on the rear of the board. Notice the location of the flat side of the LED.

 

[[File:ALDLEDlitup.JPG|300px|thumb|left|LED is lit up]] 
Finished installation with LED lit up indicating presence of +5 volts power on the board.

 

=====Sound/Speech Power Supply Board LED's=====
The Sound/Speech power supply board will get a total of four LED's! These are to indicate the presence of -12 volts, +12 volts, and +30 volts going out to the actual sound/speech board and also to indicate +24 volts coming in to the power supply board.

'''Materials needed:'''

*4 Red or green LED's
*2 Resistors, 1 k, 1/4 watt
*1 Resistor, 2.2k, 1/4 watt
*1 Resistor, 3.0 k, 1/4 watt

#Drill a total of eight 1/16" holes at the points shown in the pictures near connector A7P1. Lead spacing per LED is about 3mm. Be sure the LED's are not too close to each other to interfere with sitting flat against the board. The +12 and +30 volt LED's will mount with the flat side facing diagonally (7 o'clock) toward the lower left board mounting hole.
#The -12 volt LED will have the lead of the round side (anode) soldered to the heavy ground trace of the board. You'll need to scrape some of the green paint off the trace first. The other lead of this LED will be soldered to one end of a 1k resistor. The other end of this resistor will be soldered to the junction point of resistor R2 and the anode of zener diode CR2.
#The +24 volt LED will have the lead from the flat side (cathode) of the LED soldered to the heavy ground trace on the board. You'll need to scrape a bit of the green paint off the trace first. The other lead of the LED will be soldered to one end of a 2.2k resistor. The other end of the resistor will be soldered to the trace going to connector A7P1 pin 6 (+24 volts). Again, you'll need to scrape some of the green paint from the trace first.
#The +12 volt LED will have the lead from the flat side (cathode) of the LED soldered to the heavy ground trace. You will need to scrape some of the green paint off the trace first. The other lead of the LED will be soldered to one end of a 1k resistor. The other end of this resistor will be soldered to to the trace going to connector A7P1 pin 1 (+12 volts). You will need to scrape some of the green paint off of the trace first.
#The +30 volt LED will have the lead of the flat side (cathode) soldered to the heavy ground trace. You will need to scrape off some of the green paint from the trace first. The other lead of the LED will be soldered to one end of a 3 k resistor. The other end of this resistor will be soldered to the trace going to connector A7P1 pin 2 (+30 volts). You will need to scrape some of the green paint from the trace first.
#These LED's above are all optional. The board never originally came with anything to indicate presence of voltages. If you only want to install one, that's fine. I chose to install all four so I can see at a glance that all four voltages are present. You don't have to install all four if you don't want to.

In the picture of the finished front of the board the LED's from top to bottom are:

*-12v
*+24v
*+12v
*+30v

In the picture of the wiring on the back (foil) side of the board, the resistors top to bottom are:

*1K
*2.2K
*1K
*3K

[[File:SSPSLEDfrontholes.JPG|300px|thumb|left|Drilled holes for the LED's on the front of board]]
[[File:SSPSLEDrearholes.JPG|300px|thumb|right|Drilled holes for the LED's on the rear of board]] 
Views of the drilled holes for the LED's looking from the front and rear of the board.

 

[[File:SSPSLEDlower.JPG|300px|thumb|left|+12 and +30 LED's installed on front]]
[[File:SSPSLEDupper.JPG|300px|thumb|right|-12 and +24 LED's installed on front]] 
All four LED's installed on the front of the board. Notice the location of the flat sides of all the LED's.

 

[[File:SSPSLED_wiring.JPG|300px|thumb|left|Wiring of the resistors on the rear of board]]
[[File:SSPSLEDfinished.JPG|300px|thumb|right|All four LED's installed on front of board]] 
Wiring of the resistors and LED's on the rear of the board. All four LED's installed on front of board.

 

[[File:SSPSLEDlitup.JPG|300px|thumb|left|Finished and all LED's lit]] 
All four LED's installed and lit up indicating the presence of the four different voltages.

 

=====System 80/80A Power Supply Board LED=====
The System 80 and System 80A power supply board already has LED's installed to indicate the +5 volts and +12 volts. This project will add an LED to indicate the presence of the +60 volts which is used to operate the score displays.

'''Materials needed:'''

*1 LED, any color
*1 Resistor, 10k, 2 watts

#Drill a total of four 1/16" diameter holes at the points indicated between the foil traces in the pictures. Try to keep the holes in a straight line.The LED installs in the top two holes and with the flat (cathode) side facing downward toward the bottom end of the board. The resistor will install in the other remaining two holes which are the also the farthest spaced. Be sure to scrape the paint off of the foil traces at the points shown in the pictures.

[[File:SYS80PS_holes_front.JPG|300px|thumb|left|Holes drilled viewed from front of board]]
[[File:SYS80PS_holes_rear.JPG|300px|thumb|right|Holes drilled as viewed from rear of board]] 

 

'''Wiring it all up:'''

The flat (cathode) side of the LED will be soldered to the top end of the 10k 2 watt resistor. Be sure to keep all component leads pressed down as close to the foil traces as possible to prevent shorting to the metal frame when the board is re-assembled to the metal frame. There is very little clearance between the board and the metal frame when everything is re-assembled. The lower end of the resistor will be soldered to the foil trace that goes to connector J3, pins 4 and 5 (ground). The round (anode) side of the LED will be soldered to the foil trace that goes to connector J3 pin 1 (the +60 volts). Put a short piece of heat shrink tubing or sleeving over that lead to prevent it from shorting to the trace it crosses over. Now carefully bend that lead of the LED down onto the correct foil trace as shown in the pictures and solder it. Be sure to label the new LED on the parts side of the board as "+60V". This completes the wiring.

[[File:SYS80PS_parts.JPG|300px|thumb|left|Resistor and LED mounted on board]]
[[File:SYS80PS_soldered.JPG|300px|thumb|right|Parts soldered to foil traces]] 

 

The new LED should be lit at all times the machine is turned on. It indicates that +60 volts DC is present to operate the score displays. The other display voltage, +42 volts, is derived from the +60 volts.

[[File:SYS80PS_finished.JPG|300px|thumb|left|Finished installation with +60v marking]]

 

=====System 80 First Generation "Sounds Only" Sound Board LED's=====
This board was used in early System 80 games such as Panthera. It operates on three power sources, -12 volts, +12 volts, and +5 volts. The +12 volts is obtained from the bottom panel in the machine. The +5 volts is obtained from the game's power supply board. The -12 volts is generated on this sounds only board by receiving ac power input on J1 pins 3 and 4. You can measure the -12 volts by connecting your volt meter across zener diode CR5 (1N4742A).
 

'''MATERIALS NEEDED'''

*2 LED's, any color
*1 Resistor, 1k @ 1/4 watt
*1 Resistor, 330 ohm @ 1/4 watt
*1 Short piece of small diameter heat shrink tubing

#Drill two pairs of holes 1/16" diameter and about 3mm apart at the locations as shown in the pictures. Be sure not to drill through any foil traces.
#The +12 volt LED will have the flat side (cathode) of the LED soldered to the ground trace coming from pin 6 of connector J1. You'll need to scrape a bit of green paint off of the trace first in order to solder it. The other lead of the LED will be soldered to one end of a 1k @ 1/4 watt resistor. The other end of the resistor will be soldered to pin 1 of connector J1 (the +12 volt source). Be sure to slide a short piece of heat shrink tubing over this end of the resistor before soldering since this lead will pass over a couple of traces. This will prevent the resistor lead from shorting to those traces and causing damage.
#The +5 volt LED will have the flat side (cathode) of the LED soldered to the ground trace coming from pin 6 of connector J1. You'll need to scrape a bit of the green paint off of the trace first in order to solder it. The other end of the LED will be soldered to one end of a 330 ohm @ 1/4 watt resistor. The other end of the resistor will be soldered to pin 5 of connector J1 (the +5 volt source).
#When finished, be sure to note that the flat sides of both LED's will be facing each other on the front side of the board. 

[[File:Sys80so_holes_front.JPG|300px|thumb|left|Holes drilled in front of board]]
[[File:Sys80so_holes_rear.JPG|300px|thumb|right|Holes drill in rear of board]] 

 

[[File:Sys80so_LEDS.JPG|300px|thumb|left|LED's installed on board with flat sides facing each other]]
[[File:Sys80so_resistors.JPG|300px|thumb|right|Wiring on solder side of board]] 

 

====F2 Fuse Blows At Power Up on 80A games====
If the F2 fuse blows at power up, there is one overlooked problem that is good to check. This could also apply to 80B games, but a different fuse may blow.

On the transformer panel, there is a pair of cement resistors are soldered to a solder tab, which is screwed down to a small square plastic post. Check to make sure that this has not been moved to another screw hole in the metal of the transformer panel. Screwing this line to the metal of the transformer panel ties one of the AC lines to ground. Since this line is shorted/tied to ground, it also has the side effect of making the bridge rectifier test bad, since there is a tab tied to ground when there shouldn't be one. It is likely that the bridge rectifier will test good as soon as the solder tab is moved to the correct place.

<center>
<gallery widths=300px heights=300>
File:sys80-f2-fuse-blows-issue-2.jpg|Correct place to screw the solder tab (on the square plastic post)
File:sys80-f2-fuse-blows-issue-1.jpg|Incorrect place to screw the solder tab. This causes a short.
</gallery>
</center>
 

===MPU boot issues===

There are a large and varied number of reasons that a System 80 MPU will fail to boot. Unfortunately, as has been said before, "this is not a Bally world". That is, unlike "classic" Bally and Stern MPUs the System 80 MPU provides absolutely no indication as to why it may have failed to boot.

Debugging a non-booting MPU is somewhat of an art. A few basic steps are listed below.

#Ensure your game is providing a solid 5VDC power source
#Replace the orange electrolytic cap in the cabinet bottom if still original
#Take the board to the bench
#Examine the board for Alkaline damage. If present, clean up
#Ensure the reset section of the board is working. Pin 40 of the 6502 should begin "low", then after about 1/2 second, transition to "high"
#Check the clock signals at the 6502
#Check the IRQ signal at the 6502. Ensure it isn't "stuck"
#Check the R/W (read/write) signal at the 6502. Again, ensure it isn't stuck
#Check the address and data lines to ensure that they are pulsing
#Feel each of the masked ROM chips at U2 and U3 as well as the 6532 RIOT chips at U4, U5, and U6. If the IC is too hot to touch, it has probably failed and should be replaced. Note that the 6532 RIOTs run hot normally. If one is noticeably hotter than the other, that may be an indication of failure.
#Test each of the 74XX chips in the switch matrix (Z11 - Z15) using this [http://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit procedure].
#If the board has the original masked game ROM(s), replacement with the appropriately sized ROM is advised (generally a 2716).
#In the case of System 80B MPUs that employ a "daughter card", fractured solder joints where the "riser pins" meet the daughter card are often an issue. These joints can't be examined without removing the daughter card. And, removing the daughter card is not trivial. If flexing the daughter card causes the board to boot or to crash, fractured solder joints are a solid suspect.

====Power on "Thunk"====
Some System 80 games exhibit a "thunk" upon power up. The manifestation of this is the unpredictable lighting of lamps, running of motors, and actuation of coils / relays. The symptom is unpredictable in that swapping either the driver or the MPU board might change the behavior.

The "thunk" can be suppressed via a process detailed [http://www.flippers.com/gott-system80.html#thunk here] by John Robertson.

[[File:Sys80 Driver Reset Front.JPG|thumb|left|300px|The addition of an MCP130-460HI/TO reset generator on the driver board.]]
[[File:Sys80 Driver Reset Back.JPG|thumb|right|300px|The addition of an MCP130-460HI/TO reset generator on the driver board w/ traces cut and jumpers run.]] 
As an alternative to John's approach, another method has been developed. The method employs the use of a reset generator tied to the '''CLR''' leg (pin 1) of the appropriate 74175 flip-flops (those that control devices that "thunk"). The reset generator is added to the front of the driver board in the upper right hand corner. There is a "star via" in this location. Solder should be removed from the star via exposing a through hole. Next, two very small holes should be drilled into the board on either side of the via. Make certain not to drill through traces on the solder side of the board, and that neither hole touches the "star via". Next, scrape the solder mask from the two thick traces on the solder side which pass closest to the star via. These traces terminate at capacitor C1 on the driver board. The closest trace is ground and the other trace is +5v. Next, place a MCP130-460HI/TO reset generator through the driver board. The center leg ('''RESET''') will pass through the star via, while the outer legs will go through the newly drilled holes. The flat side of the reset generator should be facing the components on the driver board.
 
Next, bend the GND and 5V legs of the reset generator onto the appropriate traces where the masking was scraped. Next, the traces on Z3, Z4, and Z5 should be cut between pin 1 and pin 16. This is the wide trace at the very top of the chip. Additionally, there is a thick trace to the right of pin 1 on Z4 which must be severed. After cutting this trace, pin 16 and the isolated trace must be tied together with a jumper. This connects 5VDC to pin 16 of Z4. Now that pin 1 is isolated from 5VDC on chips Z3, Z4, and Z5, trace wire must be routed from the center leg ('''RESET''') of the reset generator to pin 1 of each of these chips. Once this modification is completed, the coils associated with these chips will no longer be pulsed when the game is turned on.

Like the modification which John Robertson lays out, it may not be necessary to isolate pin 1 of Z3, Z4, and Z5 for every game. However, isolating these 3 chips accommodates most System 80/A/B games that use lamp transistors to pre-drive coils / relays. The game over and tilt relays will still pulse briefly upon turning the game on but that behavior is generally acceptable. Isolating pin 1 of Z1 and tying pin 1 to the reset line of the reset generator will resolve this residual behavior.

Note that the trace wire shown in the pic on the right could have been routed more elegantly. This was in part due to an afterthought in having Z3 tied to the reset generator.

Since the "thunk" is really just a minor irritation, most owners do not think that the resolution is worth the effort. However, on some games, the thunk can be very annoying by pulsing the ball release coil under the lower apron. The result is a ball being served into the shooter lane, before the MPU board even boots up. Most System 80B Genesis games run the "Reveal Motor" as a result of the "thunk".
 

[[File:ResetGeneratorPinExplanation.jpg|thumb|left|300px|Part number explanation and pin configuration for various reset generators.]] 
Other reset generators may be used as long as the pinout of the legs is observed. Shown at left is a snippet of the datasheet that explains reset generator part numbers. 

[[File:AlternateDethunkFront.jpg|thumb|left|300px|Using an MCP130-460DI/TO reset generator. Take care to drill the holes so that only one reset generator leg touches the star.]]
[[File:DethunkAlternateBack.jpg|thumb|right|300px|Jumpers are still connected to the "star via" but the new holes are drilled in different locations.]] 
One alternate reset generator to use is the MCP130-460DI/TO which is also used in the section that discusses System 80 MPU alkaline corrosion abatement. The installation is a bit different as is shown in the adjacent pictures. The ('''RESET''') signal is on the left leg of the reset generator while Vdd (5VDC) is in the center and Vss (Ground) is on the right leg.
 

====Erratic Boot Issues with Later 80B Games (Hot Shots, Bad Girls, and Big House)====
Some erratic boot issues have been observed with the following games: Hot Shots, Bad Girls, Big House, and Excalibur, however, the list of games may be more extensive. The issues included are a locked on display with garbage characters shown, no display illuminating at all, sound board not booting (LED stuck on), locked on lamps, no controlled lamps, locked on coils, etc. The source of the problem seems to stem from the fluorescent tube starter located in the backbox. It is unknown why exactly this anomaly occurs. Removal of the starter should resolve the booting issues. Worst case scenario, remove the 110v panel fuse on the transformer panel use for the fluorescent light circuit. Unfortunately, this is the only resolution known at this time.

====Battery Leakage and Corrosion====
Like most any other pinball machine manufactured, Gottlieb® uses batteries to supply power to the non-volatile RAM memory. Certain game settings, high score thresholds (including high score to date), audit information, and bookkeeping information are all options which are saved when the game is powered off. And unless some kind soul, who worked on your machine before, either removed the battery and mounted it remotely away from circuit boards, or just plain removed the battery, there will be some variety of a 3.6v Nickel Cadmium (NiCad) rechargeable battery soldered onto your CPU board.

So, what's so bad about having a battery on the CPU board? Well, nothing really, unless it's forgotten, and in most cases, it is. While you let your pinball machine sit unplayed for weeks, months, or even years at a time, the battery remains perched on the circuit board like a ticking time bomb. I'm not saying the battery is going to blow up, although some replacement non-rechargeable batteries could overheat and / or explode if not correctly installed. The battery is like a ticking time bomb, because it is a threat to the overall health of the electronic components, traces, and connectors attached to your CPU board. 

Now that I have your attention regarding the whole battery thing, let's talk about the battery, and what happens. . .'''WHEN GOOD BATTERIES GO BAD'''. It's not that some batteries were born on the wrong side of the tracks or anything. Any good battery can go bad without much warning. It takes time, but eventually you will find that your battery has crossed over to the "dark side". That particular time is typically when you turn your game on, the lights come on, and that's it. The displays don't light up. The start up sounds don't resonant. And, the silver ball stays in its comfy little home. Nada...nothing...no signs of anything resembling a fun game of pinball. '''UH-OH!''' So what happened? The pinball machine worked fine the last time you played it.

Well, while you were out having a good time and enjoying life, the poor, aged, neglected battery decided to wreak havoc all over the reset section, clock section, or possibly more regions on your CPU board. The CPU battery spewing its guts all over the place is akin to the batteries in the flashlight you haven't turned on since the last power outage a year or two ago. You go to turn on the flashlight when you need it most, and find out there's something wrong. So being the curious type, you open the flashlight's battery compartment only to find some kind of blue-green funk leaking all over, or the batteries now look like they need a shave. The resolution to the flashlight scenario is pretty simple. Throw it away, and buy a new one. Your CPU board problem can be resolved the same way, except it will be a lot more costly, and is not recommended to just pitch it in the trash. If the battery damage to the CPU board is not overly extensive, attempt to repair it. 

[[File:Gtb sys80A bat damage01.JPG|300px|thumb|left|Typical Battery Found on a System 80 CPU Board]] 
It's unfortunate, but every battery has a life expectancy. The only silver lining is that some of the Ni-Cad batteries installed on Gottlieb® CPU boards can last longer than others. Probably the worst culprit of board destruction is the '''Data Sentry''' pack, and its associated knock-offs. This battery comes in a black rectangular plastic package. 

[[File:GTB sys80A battery.jpg|300px|thumb|left|Typical Battery Found on a System 80A / 80B CPU Board]] 
Another battery pack style which looks very similar to the NiCad battery packs found in "old school" cordless phones. It is actually three small NiCad cells wrapped separately in an orange poly material, which is wrapped in a outer white poly material. These don't leak nearly as badly, but they still have the potential to fail.
 

[[File:Replacement nicad.jpg|300px|thumb|left|Typical NiCad Battery Which was Replaced]] 
The final common battery style is a what looks like an AA battery on steroids. This style is a fraction longer and fatter than an AA battery's physical form, and has two soldered leads on either end. If you find one of these, it means the battery was previously replaced. The good news is that this battery is newer than the original. However, the same results of battery seepage can occur. The only benefit of this type of battery is that it can be carefully cut (in most cases) from the board without removing the board from your game. This is a plus if no battery damage has occurred. 

[[File:Gtb sys80A bat damage03.JPG|300px|thumb|left|NiCad Battery Damage to a System 80A CPU Board (Note: This is considered very mild damage!)]]
[[File:Gtb sys80A bat damage04.JPG|300px|thumb|right|Damage from the battery may also occur on the back side of the board, especially on the edge connection fingers]] 
So what happens if you don't heed the above warnings, and the battery is allowed to remain on the board? Plain and simple - '''THE BATTERY WILL LEAK!''' It's only a matter of time. Equally, the path of destruction is uncertain. Batteries don't just leak - they release caustic, alkaline fumes. These fumes attack wherever there is copper, even tinned or soldered copper. The end results are:

*solder joints which become green or gray and crusty as opposed to a shiny silver
*connectors which are also now green / gray or potentially broken
*solder mask, the green covering the electronic traces, on the circuit board has either flaked off or is partially delaminating (lifting)
*insulated wire becomes less flexible and brittle
*sometimes the alkaline "cloud" in the game's backbox causes every board in the head to be affected.

Electronic components, related solder joints, circuit board traces, connectors, and even insulated wire will become unreliable and/or fail. In all cases, the affected components are less conductive. 

If battery damage has occurred, the related parts must now be replaced. Attempting to remove soldered through components on the circuit board is now even more of a task. The green / gray dull solder does not transfer heat well. Battery damaged solder does not flow like clean solder. Also, crimped connectors are more difficult to remove from their housings, and have a tendency to break before they can be successfully pulled out. 

After all the effected electronic components are removed, the board must be treated. This process starts by sanding the traces and solder pads until shiny copper is exposed. It is worth mentioning that a battery damaged board can be treated by bead blasting instead of sanding, however, most people do not have access to such a machine. After the copper areas of the board have been either sanded or bead blasted, an acidic bath of 50% vinegar and 50% (preferably distilled) water is applied to the board. A small brush like a toothbrush can be used to scrub the board's area. The purpose of introducing an acid to the effected area is to neutralize what the battery has left behind. The liquid and fumes from the battery are actually a base, not an acid. Next, rinse the area of the board with water. Once the board is clean, isopropyl alcohol (the higher the alcohol percentage the better) is applied to the same area to rinse away the acid bath, and hopefully dissipate any remaining water. Finally, the board is either blown dry or air dried. This may be a given, but '''DO NOT ATTEMPT TO APPLY POWER TO THE BOARD IF IT IS STILL WET!''' Most liquids are conductive to some extent. After the previous steps are performed, the task of installing the new components begins. If any traces or solder pads were damaged, see the [http://www.pinwiki.com/wiki/index.php?title=General#Repairing_traces_or_creating_a_.22solder_stitch.22 Repairing Traces] portion of this Wiki guide on to to fix them. 

The point I'm trying to ultimately make is this...regardless of age, shape, or form, '''remove the battery from the CPU board''', as soon as it realized that there is a battery on the board. If not, the board can be damaged, nonfunctional, and become more difficult or even impossible to repair.
 

====Relocating the battery from the MPU board====
The first thing that should be done to any System 80 MPU is remove the rechargeable NiCad battery from the MPU board. All batteries leak. They are like ticking bombs. It is merely a matter of when they will leak and possibly damage (sometimes irreplaceable) boards.

There are at least five methods of relocating and/or replacing the battery on a System 80/80A/80B MPU.

*Remove the battery completely without replacing it. The 5101 memory will not store information from power-on to power-on and therefore, high scores, replay levels, and credits will be lost.
[[File:System80battery.jpg‎|300px|thumb|right|Remote Battery]] 
*Mount a remote battery pack that uses standard AA batteries (x3) to protect your board. A blocking diode must be installed (1N4004, although a 1N4001 will work just as well) to prevent the game circuitry from attempting to charge the batteries. Install the blocking diode in series with the positive lead of the battery pack, with the band oriented toward the MPU.
 
[[File:MemorySuperCap.jpg‎|300px|thumb|right|Here a 5.5V, 1F Super Cap is used to retain 5101 memory for up to 30 days]] 
*Replace the battery with a 1F 5.5V "SuperCap". The capacitor will never leak, will charge during power-on cycles, and will retain 5101 memory for about 30 days. If you've sanded traces as was done in the picture, use a non-conductive material to cover the trace under the cap to ensure that the negative side of the cap doesn't short a trace (such as clear nail polish, green overcoat pen, electrical tape, or fishpaper). Cut the tape in a circular shape and poke the capacitor leads through it so it can't fall off in the future. (Electric tape is notorious for slipping.) An alternate solution would be get a piece of fishpaper insulator, cut that into a circle and poke holes in it for the capacitor leads.
 
[[File:GTB Sys80 H Mem Cap.JPG|300px|left|thumb|Alternate method for installing a memory cap]]
[[File:GTB Sys80 H Mem Cap Back.JPG|300px|right|thumb|Tying the negative lead of the memory cap to the negative pad on the MPU board]] 
The memory cap can also be installed in the two leftmost holes, where the Ni-Cad battery formerly resided. The negative lead of the memory cap will then have to be tied to the negative (ground) through hole of the MPU.
 
*Remotely mount a replacement NiCad battery in a location that, should it leak, won't damage valuable circuit boards. 
[[File:GottliebCR2032.jpg‎|300px|thumb|left|a CR2032 Lithium "Button Cell" Battery Installed]]
[[File:GottliebBlockingDiode.jpg‎|300px|thumb|right|A 1N4004 Blocking Diode Installed "inline" with the Positive Connection]] 
*Replace the original NiCad battery with a Lithium button cell CR2032 battery and holder. The holes for the original battery can be repurposed to connect the button cell holder and to add the necessary blocking diode in the positive side of the circuit.
 

====Using a Reset Generator for the CPU Reset Section ====
If you find that the battery has leaked, alkaline damage can be cleaned up, traces repaired, and new components installed with kits available from several sources, including Great Plains Electronics.

An alternative to replacing a great many of the components is to use the Dallis/Maxim DS1811 reset generator. The DS1811-10 has a typical trip point of 4.35VDC. You may also use the Microchip Technology equivalent, part number [http://www.greatplainselectronics.com/proddetail.asp?prod=MCP130-460DI%2FTO MCP130-460DI/TO], available from Great Plains Electronics. Remove all reset section components, clean up residual alkaline damage, add four jumpers, and install the reset generator as pictured below. 

After jumpers and the reset generator are added, make certain there is continuity between the three legs of the reset generator and the appropriate locations on the circuit board. Below is a list of the reset generator legs and the board locations. Pin 1 of the reset generator is the left leg, when the flat side of the unit is facing towards the user.

*Pin 1 of reset generator to pin 2 of Z4
*Pin 2 of reset generator to +5VDC line (lower leg of C2)
*Pin 3 of reset generator to ground (upper leg of C2)
 

<center>
<gallery widths=300px heights=300px perrow=3 caption="Using the Dallas Maxim 1811 Reset Generator">
File:Dallas_Maxim_Reset_scaled.JPG|A System 80 MPU with alkaline damage repaired/cleaned. Reset circuitry replaced with the much simpler Dallas Maxim 1811
File:Gtb sys80 reset gen jumpers updated.png|Illustrated picture of components to remove, keep, and jumpers to add.
File:Dallas_Maxim_Reset_scaled_with_markup.JPG|The same image, but with indications of jumper locations (yellow dots) and where to install the Dallas Maxim 1811, flat side facing the bottom of the board. Note: View at full resolution
</gallery>
</center>
 

<center>System 80 Corrosion Area Parts Identification</center> 
[[File:System80CorrosionAreaPartsIdentification.jpg|1000px|center|System 80 Corrosion Area Parts Identification]] 

[[File:GTB Sys80 MCP120 Reset Gen.JPG|300px|left|thumb|MCP120 reset generator installed with 4.7K pullup resistor]] 
If a reset generator with an internal pullup resistor (MCP130 series) is not available, an MCP120 reset generator can be installed. However, an external resistor must be installed between the reset and +5v. The easiest location to install the resistor is between the through hole where the top leg of Q4 was, and through hole where the bottom leg of Q2 was. In the adjacent image, an MCP120-460DI/TO is installed with the 4.7K 1/4 watt external pullup resistor highlighted. 

When installing this type of reset generator, remove all of the components, and add all of the jumpers related to the installation of an MCP130-460DI/TO reset generator. Adding the external pullup resistor is the only additional step. Failure to add the pullup resistor will result in the reset signal not going high, and the board will not boot.
 

==== Slam Switch Modification ====
In order to test the CPU board on the test bench, a modification must be made to the CPU board to make the CPU think that the slam switch is closed. If the CPU thinks that the slam switch is not closed, the CPU will not complete the boot process, instead booting into a mode where the displays flicker all zeros at a very rapid rate (System 80 and 80A). See the image [[Gottlieb_System_80#Open_Slam_Switch | here]] for a depiction of what you'll see. When the slam switch is open on a System 80B game, (the appropriate games where the slam switch is supposed to be closed), an "OPEN SLAM SWITCH" message will be shown on the display. 

Gottlieb® designed the slam switch as a normally closed switch. That is, the switch must be closed for the machine to operate normally. When a brute kicks the machine, the slam switch will open from the inertial force on the weight attached to the switch, and the slam switch will open. Since the CPU is on the bench, we need a way to have this switch closed at all times to properly test the board.

Additionally, slam switches themselves fail. It's a good idea to implement this change as a preemptive fix for slam switch failures.
 

[[File:Slammod.png|300px|thumb|left|Slam Switch Mod]] 
The slam switch can effectively be permanently closed by making a small solder bridge across two traces to the right of Z26 (which is on the lower right side of the CPU board). To permanently close the switch, remove the solder mask by scraping with a sharp knife or screwdriver. Create the solder bridge between the two now bare traces. This change will connect pin 13 of Z26 to ground, permanently closing the switch.
 

[[File:DefeatSlamSwitch.jpg|300px|thumb|left|Alternative Slam Switch Mod]]
[[File:Z26RemovedSlamSwitch.jpg|300px|thumb|right|Z26 removed. One can easily see that the two methods of defeating the Slam switch are equivalent.]] 
An alternate method of achieving the same results is to solder a clipped resistor leg across the bottom of capacitor (C30) and resistor (R20), both immediately to the left of Z26.
 

[[File:Ni-WumpfSlamMod.jpeg|300px|thumb|left|Slam Switch Mod for Ni-Wumpf CPU Board]] 
To permanently close the slam switch on a Ni-Wumpf CPU board, you need to connect pin A1J5-10 to ground on the board. This picture shows how to do this from the back of the board by soldering a jumper wire.
 

Keep in mind that the last 4 Gottlieb® System 80B games were released with normally open slam switches. Do not perform the slam switch modification on these games. This includes the following games:
*Bad Girls
*Big House
*Hot Shots
*Bonebusters, Inc.
*Night Moves (made by International Concepts using the 80B board set)

Regardless of what platform the game is based on, there is only one slam switch used in a System 80/80A/80B game. It is the weighted switch located on the coin door. There is some confusion that the ball roll tilt and weighted tilt switch on the playfield are slam switches. They are not. These switches along with the pendulum tilt are all tilt switches.
 

==== System 80B Daughter Board Solder Joints ====
[[File:GTB sys80B CPU.JPG|300px|thumb|left|A typical System 80B MPU Board, showing the location of the "daughter board".]]
[[File:System80BFracturedJointsDaughterCard.jpg|thumb|right|300px|A closeup of Gottlieb® System 80B Daughter Board Male Header Pins with fractured solder joints. This board was cleanly removed from the CPU with great care.]]
Games with System 80B MPUs feature a "daughter board" to accommodate the 2764 game ROM as shown in the picture on the left. The daughter board connects to the MPU board at the location occupied by U3 in System 80/80A MPUs, via a 24-pin male header. That connection is a two-sided solder joint that can fail. As can be seen in the picture at right, these same header pins connect to the daughter board via a single sided solder joint. Since the daughter board is cantilevered over both the former location of U2 and U3, pressing on this board over time commonly results in fractured solder joints (as seen, right) at the single sided joint and sometimes at the two-sided joint.

Typical symptoms of fractured solder joints at this location are failure to boot, random resets, and random lockups. Sometimes pressing on the daughter board will "fix" the issue temporarily. This is a sure indication of cracked solder joints.

Correction of this issue is easier said than done. And, if you do not possess the tools, skills, and experience to desolder the daughter board, this task is best left to a professional pinball circuit board repair technician. Desoldering the 24 male header pins from the delicate solder pads without damaging the pads or pulling traces is non-trivial. 

=====Continuity Chart of Pinouts for Damaged U2 / U3 Area=====
It is far too easy for inexperienced technicians to tear up the traces or eyelets at positions U2 and U3 when attempting to remove the daughter board from the System 80B MPU. If the traces or through holes are damaged, clearly they must be repaired. Nearly all of the signals which pass from U2 and U3 continue on to the 3 RIOTs at U4, U5, and U6 and also to the PROM 1 position. Below is a handy chart which can be used to ensure continuity between critical parts.

{| class="wikitable" style="margin: 1em auto 1em auto;"
!      U2 Pin      
!      U3 Pin      
!      U4, U5 & U6 Pin      
!      U1      
!      Signal      
!      Other      
|-
|<center>1</center>||<center>1</center>||<center>--</center>||<center>16</center>||<center>A7</center>||<center></center>
|-
|<center>2</center>||<center>2</center>||<center>40</center>||<center>15</center>||<center>A6</center>||<center></center>
|-
| <center>3</center>||<center>3</center>||<center>2</center>||<center>14</center>||<center>A5</center>||<center></center>
|-
| <center>4</center>||<center>4</center>||<center>3</center>||<center>13</center>||<center>A4</center>||<center></center>
|-
| <center>5</center>||<center>5</center>||<center>4</center>||<center>12</center>||<center>A3</center>||<center></center>
|-
| <center>6</center>||<center>6</center>||<center>5</center>||<center>11</center>||<center>A2</center>||<center></center>
|-
| <center>7</center>||<center>7</center>||<center>6</center>||<center>10</center>||<center>A1</center>||<center></center>
|-
| <center>8</center>||<center>8</center>||<center>7</center>||<center>9</center>||<center>A0</center>||<center></center>
|-
| <center>9</center>||<center>9</center>||<center>33</center>||<center>33</center>||<center>D0</center>||<center></center>
|-
| <center>10</center>||<center>10</center>||<center>32</center>||<center>32</center>||<center>D1</center>||<center></center>
|-
| <center>11</center>||<center>11</center>||<center>31</center>||<center>31</center>||<center>D2</center>||<center></center>
|-
| <center>12</center>||<center>12</center>||<center>1</center>||<center>1,21</center>||<center>GND</center>||<center></center>
|-
| <center>13</center>||<center>13</center>||<center>30</center>||<center>30</center>||<center>D3</center>||<center></center>
|-
| <center>14</center>||<center>14</center>||<center>29</center>||<center>29</center>||<center>D4</center>||<center></center>
|-
| <center>15</center>||<center>15</center>||<center>28</center>||<center>28</center>||<center>D5</center>||<center></center>
|-
| <center>16</center>||<center>16</center>||<center>27</center>||<center>27</center>||<center>D6</center>||<center></center>
|-
| <center>17</center>||<center>17</center>||<center>26</center>||<center>26</center>||<center>D7</center>||<center></center>
|-
| <center>18</center>||<center>18</center>||<center>--</center>||<center>--</center>||<center>BAB11</center>||<center>Z10 Pin 4</center>
|-
| <center>19</center>||<center>19</center>||<center>--</center>||<center>--</center>||<center>BAB10</center>||<center>Z12 Pin 10</center>
|-
| <center>20</center>||<center>20</center>||<center>--</center>||<center>--</center>||<center>BAB13</center>||<center>Z10 Pin 6</center>
|-
| <center>21</center>||<center>--</center>||<center>--</center>||<center>--</center>||<center>BAB12</center>||<center>Z10 Pin 12</center>
|-
| <center>--</center>||<center>21</center>||<center>--</center>||<center>--</center>||<center>/BAB12</center>||<center>Z7 Pin 10</center>
|-
| <center>22</center>||<center>22</center>||<center>--</center>||<center>18</center>||<center>A9</center>||
|-
| <center>23</center>||<center>23</center>||<center>--</center>||<center>17</center>||<center>A8</center>||
|-
| <center>24</center>||<center>24</center>||<center>20</center>||<center>8</center>||<center>+5V</center>||
|}

=====System 80B Daughter Board Replacement Options=====
[[File:U2U3AdapterGPE.jpg|300px|thumb|left|Replacement daughter board engineered by Great Plains Electronics. ''Image used with permission from Great Plains Electronics.'']] 
Great Plains Electronics produced a better replacement daughter board. This board is designed to be installed in both the U2 and U3 sockets, eliminating the problem of board flex and cracked solder joints with the daughter board. Unfortunately, it is no longer available. If it needs to be installed on an MPU (especially where the U2/U3 chips are not socketed for easy removal), it is recommended to desolder the chips, fit the replacement board into quality machine pin sockets, then fit the entire assembly into the MPU board for soldering. The board is also designed with redundant traces for all but a few of the signals, as almost all signals are present at both the U2 and the U3 sockets.

Pinitech has another replacement option called [https://www.pinitech.com/products/gottlieb_piggydeux.php Piggy Deux], but at the time of writing, it is not currently available. This module fits into the TC1 test socket near top of the MPU, which saves a lot of trouble by not requiring removal or repair of the original daughter board. The 2764 EPROM chip simply needs to be removed from the original daughter board and installed into the Piggy Deux module.
 

=====An Alternate to the Daughter Board on System 80B MPU Boards=====
[[File:GTB Sys80B Alt D-Board.jpg|thumb|left|300px|An 80B MPU Board with an MCM68766 PROM installed at U3 (Genesis)]]
[[File:GTB Sys80B Raven No D-Board jecourie.jpg|thumb|right|300px|An 80B MPU Board with an MCM68766 PROM installed at U3 (Raven)]]
[[File:GTB Sys80B Alt D-Board_Back.jpg|thumb|left|300px|An 80B MPU Board with an MCM68766 PROM installed at U3 - Back Side (Genesis)]]
[[File:GTB Sys80B Raven No D-Board back jecourie.jpg|thumb|right|300px|An 80B MPU Board with an MCM68766 PROM installed at U3 - Back Side (Raven)]]

[[File:GTB_Sys80B_Alt_D-Board_Cut_Trace.jpg|thumb|left|300px|Trace cut on an 80B MPU Board with an MCM68766 PROM installed at U3 (Genesis)]]
 

==== Connecting a logic probe to the MPU ====
A great place to source power for your logic probe while diagnosing the board is across the filter capacitor in the vicinity of connector J1. Connect the black lead of your logic probe to the negative lead of the capacitor for ground. Connect the red lead of your logic probe to the positive lead of the capacitor for 5V. The red lead can also connect to E1, the vertically-aligned 5V jumper wire, below the 6502 chip. Take care to ensure that the clips don't short to adjacent components.

==== Using a PC Power Supply For Bench Testing ====
The MPU board is much easier to work on if it is removed from the backbox and placed on the test bench. An AT-style PC power supply can be used to power the MPU board on the bench.

Obtain an old PC power supply. If you don't have an old computer laying around, head on off to the thrift store and pick one up. Remove the power supply from the case by unscrewing the appropriate screws. Be careful not to unscrew the power supply case itself.

[[File:PowerSupply.png|300px|thumb|left|Power Supply]] Clip one of the connectors from the power supply wire bundle and clearly mark on the power supply box the value of each of the colored wires from the power supply. Typically, the yellow wire is 12V, red is 5V, and the black is ground. Strip insulation from the end of the red wire and the black wire as the System 80 MPU requires only 5V and ground to boot. Use alligator clips to connect 5v and ground to the appropriate J1 connection. I use larger alligator clips to make the connection easier.

 

[[File:MPUPower.png|300px|thumb|left|J1 Connector]] 
Mark connector J1 where the positive and negative (common) connection is for the five volts from the computer power supply. The ground connection is on the top of the connector, the 5V connection is on the bottom. The image shows A1J1 with the markings. I took the picture with the board still mounted in the machine. Connect the 5v supply with alligator clips to the positive connector on J1 and the black wire (ground) to the negative connector of J1.
That's it! you're good to go!
 

====List of Acceptable TTL Chip Substitutes on a System 80 CPU Board====
Several years ago, Ed from GPE replied to a System 80 chip substitution question on rec.games.pinball [http://groups.google.com/group/rec.games.pinball/msg/86f37cb479ece4c4 here] and later on Pinside [https://pinside.com/pinball/forum/topic/gottlieb-system-80-chip-replacement#post-4139713 here]. The info from those responses are summarized below. 

"Most of the parts can be freely substituted. But many cannot. The clock oscillator circuit (Z3) is one example of a part that cannot be subbed. Also, some IC's have hefty loads and cannot be subbed (some of the 7404's and a 7432). The 7474 in question on this board can be freely subbed with a 74LS74 or a 74HCT74. I went through all the standard logic devices on the Gottlieb System 80 MPU. Based on loading and output characteristics, this is what I get as valid subs for the System 80 MPU. Of course, substituting some of the parts will ripple through and allow others to be substituted as well - but this can get quite convoluted."

{| class="wikitable" style="margin: 1em auto 1em auto;"
!Chip Designation
!Part #
!Substitute (Y/N)
!Acceptable Substitutes
|-
|Z1 || 4528 || N ||
|-
|Z2 || 7474 || Y || 74LS74 and 74HCT74
|-
|Z3(1) || 7404 || ? || Possibly 74LS04 and/or 74F04; See note below
|-
|Z4 || 4081 || N ||
|-
|Z7 || 74LS04 || Y || 74HCT04
|-
|Z8 || 7402 || Y || 74LS02 and 74HCT02
|-
|Z9 || 7400 || Y || 74LS00 and 74HCT00
|-
|Z10(2) || 74LS05 || N || See note below
|-
|Z11(3) || 7404 || N || See note below
|-
|Z12(3) || 7404 || N || See note below
|-
|Z13(4) || 7400 || Y || 74LS00 and 74HCT00
|-
|Z14(4) || 7400 || Y || 74LS00 and 74HCT00
|-
|Z15 || 7432 || Y || 74F32 and 74S32
|-
|Z16(5) || 7404 || N || See note below
|-
||Z17 || 7404 || Y ||74LS04 and 74HCT04
|-
||Z18 || 74175 || Y ||74LS175 and 74HCT175
|-
||Z19 || 7448 || Y ||74LS48
|-
||Z20 || 74175 || Y ||74LS175 and 74HCT175
|-
||Z21 || 7448 || Y ||74LS48
|-
||Z22 || 74175 || Y ||74LS175 and 74HCT175
|-
||Z23 || 7448 || Y ||74LS48
|-
||Z24 || 7404 || Y ||74LS04 and 74HCT04
|-
||Z25 || 74154 || Y ||74LS154 and 74HCT154
|-
||Z26 || 7404 || Y ||74LS04 and 74HCT04
|-
||Z27 || 7404 || Y ||74LS04 and 74HCT04
|-
||Z28 || 74LS139 || Y ||74HCT139
|-
||Z29 || 7416 || Y ||7406
|-
||Z30 || 7416 || Y ||7406
|-
||Z31(6) || 7408 || Y ||74LS08
|-
||Z32 || 7417 || Y ||7407
|-
||Z33 || 74154 || Y ||74LS154 and 74HCT154
|-
||Z34(7)(8) || 7404 || Y ||74LS04, see note below
|-
||Z35(7) || 7404 || Y ||74LS04
|-
||Z36 || 4069 || N ||
|}

(1) Note: Z3 cannot use a 74HC04 or 74HCT04, since these have "high impedance inputs" and won't work properly in an oscillator circuit. A 74LS04 should work, and possibly 74F04, but the better candidate would be a 74LS04.

(2) Note: Untested, but it may be possible to use an 74LS00 or 74HCT00 at Z10 in place of 7405. However, this will defeat the ability to test the MPU using the [https://www.greatplainselectronics.com/proddetail.asp?prod=120-102 QuickScan80 tester].

(3) Note: Z11 & Z12 only have to sink ~2mA, so they might be able to be replaced with 74LS04, but this might result in noisy switching.

(4) Note: Z13 & Z14 are in the switch matrix. 74LS00 might a possible substitute, but substitutions can result in noisy switching, and isn't recommended here.

(5) Note: If Z18, 20, and 22 are 74175, do not substitute. If Z18, 20, and 22 are 74LS175 or 74HCT175, acceptable subs are 74LS04 and 74HCT04.

(6) Note: Z31 can use 74LS08. 74HCT08 can be used as well, but 74HCT08 is not a good board-to-board driver, and isn't the best option here.

(7) Note: 74HCT04 can be used at Z34 & Z35 as well as 74LS04, but 74HCT04 is not a good board-to-board driver, and isn't the best option here.

(8) Note: Had issues with a 74LS04 installed at Z34 in a Haunted House. The side effects were the lower playfield VUK would fire and partially lock on when the lower playfield 5-bank drop target would reset. Also, the 5-bank drop target would continuously tried to reset when the lower playfield VUK switch was closed. The issue acted as if there was a switch matrix issue, but there wasn't.

====Replacing the quartz crystal with a TTL Oscillator====

Alkaline corrosion may damage the board in such a way that it's advantageous to replace the original quartz crystal oscillator with a TTL oscillator.

[[Image:Clock_logic_sys80.jpg|300px|thumb|left|Clock section of the system 80 MPU]]
[[Image:oscillator.jpg|300px|thumb|right|The original crystal, Z3, and a few resistors may be replaced with a 900 kHz TTL Oscillator that is packaged like this 16Mhz version.]] 
The System 80 clock signal is produced by a 3.57Mhz crystal, a few resistors, and Z3 (a 7404). Z2 divides the clock by 4, resulting in a clock signal of approximately 900 KHz, which is provided at pin 9 of Z2.
 

If you cannot find a 900 KHz TTL oscillator (I couldn’t) you can also use the 1MHz variant, and tune your pin up a little bit. ;-) Game play shouldn't be impacted, as long as the game doesn't have a timer related feature, like Timeline. Even games like Timeline will be minimally impacted.

[[Image:Clock_system80_vorher.jpg|300px|thumb|left|The original clock section as found on every System 80, 80A and 80B MPU]]
[[Image:Clock_system80_nachher.jpg|300px|thumb|right|The clock section after installing a TTL oscillator.]] 
To accomplish this mod, remove the following parts
*Y1 (Crystal)
*Z2 (TTL 7474)
*R3, R4 und R5 ( the three resistors above Z2).

Z3 is still needed for other functions. Leave it in place. Now place the oscillator in the Z2 position, with the ‘dot’ in the upper left corner (Pin 1). Because we need the clock signal at pin 9, jumper from pin 8 to pin 9 at the original Z2 position.
 

====Using a WDC 65C02 in a System 80/80A/80B MPU====
Western Design Center (WDC) has reproduced the 6502 in a CMOS version designated 65C02. It works perfectly in all System 80 MPUs with one modification. Pin 36 of the 65C02 must be pulled up to Vcc (5VDC) via a 3K (or 3.3K) pull-up resistor. Pin 36 (BE) is the "bus enable" input which allows external control of the 65C02 busses. Pin 36 is unused by original 6502s and not connected to anything on System 80 MPU boards. Simply tack soldering a 3 - 3.3K resistor between pin 36 and a 5VDC trace will do the trick.
 

===Game Resets===
System 80 games sometimes exhibit "resets", especially when high power coils fire. Assuming you've updated the power supply grounds and reflowed or replaced the header pins on the Power Supply, there are a few typical causes for System 80 resets. 

[[File:Gtb sys80 bad caps.JPG|140px|thumb|left|Gottlieb® System 80A Filtering Capacitors]] 
#The 12VDC filter capacitor in the cabinet bottom which, if still original, should always be replaced. Originally, this was a 6800uf/25V capacitor. Replace with a 6800uf to 12,000uf/25V cap such as [http://www.greatplainselectronics.com/search.asp?pg=1&stext=RCT123M025V3550B&sprice=&stype=&scat=| this one] from Great Plains Electronics. The filtered 12VDC is regulated down to 5VDC on the power supply board. Note that some games have two of these capacitors (as shown). Note: purchase a [http://www.greatplainselectronics.com/search.asp?pg=1&stext=VR3A&sprice=&stype=&scat= VR3A capacitor clamp] from Great Plains Electronics when replacing the large capacitor for a clean looking job.
#The bridge rectifier that originates the 12VDC
#Missing, broken, or failed coil diodes
#Poor 5VDC power connections between the power supply and the MPU. The female connector on the MPU connects 5VDC to the MPU via molex crimp-on pins and a "double-wide" edge connector pad. Ground is connected in the same way. But you've done the ground mods, right?
 

====System 80A / 80B Resets====
A failed or failing reset board can ''cause'' resets. The reset board may cause problems all of the time, or just when the game is under stress, like multiball.

To see if the reset board is the problem, disconnect it. If disconnecting the reset board resolves the issue, there are two fixes:

* Replace the large caps (C3 and C4). These have dried out over the years and screw up the timing of these boards.
* Leave the reset board disconnected—if someone will always be in the general vicinity of the game to turn it off should the CPU lock up.

When first trying to get a System 80A or System 80B game to boot properly, it is best to disconnect the reset board until the game is working.
 

Electrolytic capacitors C3 and C4 are both 470 uf @ 16 volts. C1 is a 47 uf @ 16 volts. Be careful when unsoldering these capacitors as the foil traces are very delicate. The connector pins also develop bad solder joints so it is wise to resolder it.
 

===Updating a dual game PROM MPU (1st generation) to a single game PROM configuration (2nd generation)===

As noted earlier, the first five system 80 games used both sockets at PROM1 and PROM2, populating them with 512 byte masked ROMs. Should one of these ROMs fail, you may be able to find a replacement, but they are becoming more pricey, more difficult to find, and are still prone to failure as they age.

A more flexible solution would be to update the MPU to use a single 2716 UVEPROM at the PROM1 socket.

Modifications must be made to both the solder side and the component side of the board. See the pictures below.

Component side modification:
#Cut the trace that extends from the left of Z10 between pins 6 and 7. A Dremel with a "ball shaped" cutter bit works beautifully for this. In the second picture below, the cut has already been made. I've filled the cut hole with black Sharpie! to better show the location of the cut.

Solder side modifications:
#Cut the traces leading to PROM1 socket, pins 19 and 21. Again, the cuts have been highlighted with black Sharpie!
#Jumper from the PROM1 socket, pin 19, to the PROM2 socket, pin 21 (connects A10)
#Jumper from the PROM1 socket, pin 21, to the PROM2 socket, pin 24 (connects +5V to Vpp)
#Jumper from the PROM1 socket, pin 22, to the PROM2 socket, pin 18 (connects A9)
#Jumper from Z10, pin 13 to the via just below and to the right of Z9 (as you view the back of the board)

Your MPU board is now configured for any System 80 game. All that remains is to acquire a 2716 EPROM containing the game's code. If you have the original ROM images, the DOS command to combine them is shown below. Modify as appropriate to match the file names you have.

copy /b prom1.bin + prom2.bin combined.716

The MPU may also be used in a System 80A game if U2/U3 are updated, and in a System 80B game if considerably more mods are made which frankly, just aren't worth it.

<center>
<gallery widths=400px heights=400px perrow=2 caption="System 80 1st Generation to 2nd Generation Board Updates">
File:DremelBallCutter.jpg|<center>Dremel Tool with "Ball Cutter"</center>
File:Z10TraceCut.jpg|<center>Cut in trace extending Left from Z10</center>
File:PROM2-to-PROM1JumpersAndTraceCuts.jpg|<center>PROM2-to-PROM1 Socket Cuts and Jumpers</center>
File:Z10-Pin13-to-ViaJumper.jpg|<center>Jumper connecting Z10, pin 13 to a "via"</center>
</gallery>
</center>

===Using a 2732 at the PROM2 position in a System 80B MPU===
====...in games that "normally" use a 2716====
It is easy to use a 2732 at position PROM2 with an MPU jumpered to use a 2732 for a game that normally populates that position with a 2716. Simply "double-up" the 2716 ROM image, and burn it into a 2732.

The DOS command to accomplish this is ... copy /b image.2716 + image.2716 image.2732 

====...using an MA-1133 or MA-774 MPU in games that REQUIRE a 2732====
Some System 80B games require 4K of code space at PROM 2, which dictates a 2732 EPROM. An MPU built to use a 2716 EPROM at PROM2 can be modified to work, as is discussed below.

The CPU schematics of game manuals, such as "Bad Girls" and "Big House", state that E3 is directly connected to AB15 (address bus 15). However, there is no mention of the factory modification (outlined below) performed on CPU boards stamped MA-1133. Equally, should the user have an MA-774 CPU board, (used in games starting with Chicago Cubs Triple Play and ending with Robo-War), this modification can be performed to use the board in the following games. 

*Excalibur
*Bad Girls
*Big House
*Hot Shots
*Bone Busters, Inc.
*Night Moves (made by International Concepts using the 80B board set)

PROM2 is actually located at the socket marked "PROM 1" on the PCB. The area on the board marked "PROM 2", which has solder pads but no socket, is a legacy carried over from the first generation System 80 CPU board. 

The following information was taken from a service bulletin located in the back of the 1992 Gottlieb® parts catalog. This modification makes AB15 available to PROM 2, allowing the use of a 2732 EPROM at this position.

This procedure can be used in reverse if you have an MA-1133 board and you need to use a 2716 at position PROM2. 

Procedure:
#If jumper E4 is installed, remove it. You will find the top of the E4 jumper located immediately to the right of the socket marked "PROM 1".
#Install a jumper at E3. This connects the pad marked E3 to the dual pad marked E4.
#On the solder side of the board, follow the trace from the pad marked E3 Southeast 1/8 inch, then South about 1/2 inch to a via.
#Find this via on the component side of the board. It will extend to the left to another via.
#Cut the trace between the two vias.
#On the solder side of the board, install a jumper from TC1, pin 35 to the right solder pad of the via which was just cut.
#All other jumpers should remain installed.

<center>
<gallery widths=400px heights=200px perrow=2 caption="System 80B PROM 2 2732 Update">
File:GTB_sysS80b_2732_prom2_front.JPG|<center>E4 removed, E3 installed, and trace cut below E3</center>
File:GTB sysS80b 2732 prom2 back.JPG|<center>Jumper from TC1 pin 35 to E3</center>
</gallery>
</center>

Alternate Method 

There is an easier and cleaner method that allows the use of a 2732 ROM at the PROM2 position. This method is also easier to revert back.

Procedure:
#Remove jumpers E3 and E4 which are located to the right of the socket marked "PROM1".
#On the solder side of the board, install a jumper wire from TC1, pin 35, to either the upper pad marked E3 or the lower pad marked E4. These two pads are connected together on the component side of the board.
#All other jumpers should remain installed.
#Leave all traces intact. No cuts!
#That's it!

<center>
<gallery widths=400px heights=200px perrow=2 caption="System 80B PROM 2 2732 Update (Alternate Method)">
File:GTB Sys80B Alt Jump2.jpg|<center>Both jumpers E3 and E4 are removed.</center>
File:GTB Sys80B Alt Jump.jpg|<center>Jumper from TC1 pin 35 to either upper E3 pad or lower E4 pad.</center>
</gallery>
</center>
 

===Solenoid problems===

====The Driver Board====

[[File:Gtb sys80 drvr pw.png|300px|thumb|left|The System 80A / 80B Driver Board]]
The System 80 Driver board is responsible for all controlled lamps, relays, and all solenoids in the game. The CPU controls the driver board operation via a simple interface between A1J4 on the CPU and A3J1 on the driver board. Although the driver board went through some minor changes over the years, the same board can be adapted for all of the System 80 platforms. 

To control the games' total of 52 '''lamp circuits''', the interface provides "device select" signals for each of the 74175s (Quad-D Flip-Flops) on the driver board, and 4 "bits" of data that is loaded (or "clocked") into a particular 74175 via the aforementioned device selects. Each lamp is driven discretely by a particular output of a particular 74175, which in turn drives an MPS-A13 or MPS-U45 transistor, (NDS-U45 transistors were used in place of MPS-U45s in some cases). 

It is noteworthy that there are some dedicated transistors, which control specific game relay coils across the System 80 / 80A platforms. Relays such as the game over, tilt, and coin lockout relays are controlled by Q1, Q2, and Q3 respectively. The tilt and game over relays use the same designation for the System 80B platform, however, the use of a coin lockout relay was abandoned by this time. 

[[File:Gtb_sys80_drvr_board_coin_ctrs.JPG|300px|thumb|left|Driver Board with Coin Counter Transistors Highlighted ]] 
To control the games' '''solenoids circuits''', the driver board uses signals directly from the CPU to enable transistors on the driver board which turn on up to 9 solenoids. For solenoid control, the driver board uses MPS-U45, 2N3055, and 2N6043 transistors. Starting and ending with the System 80 platform, (games from Spiderman to Haunted House), three transistors were reserved to drive optional mechanical coin counters. These mechanical coin counter solenoids and associated transistors are: solenoid 3 (Q54), 4 (Q55), and 7 (Q56). Starting with the System 80A platform, (Devil's Dare), these transistors were no longer reserved for coin counters, and were used for other functions. Equally, the 3 diodes associated with these 3 transistors were changed to 3 zero ohm jumpers. 

The games' '''sound''' signals (S1, S2, S4, S8) also pass through the driver board at Z13, a 7404 Hex Inverter. See below for S16 and S32.
 

====Repurposed Driver Board Circuits====
[[File:Gtb under pf transistor.JPG‎|300px|thumb|left| A Typical Remote Transistor Mounted Under the Playfield]] 
Since quite a few System 80 games employ more than 9 solenoids, and since the original driver board design will drive a maximum of 9 solenoids, Gottlieb® repurposed some lamp outputs to drive "under-playfield transistors" which drive additional solenoids.
 

[[File:Gtb ma1011 trans board.JPG‎|300px|thumb|left| A Typical Transistor Driver Board]] 
Once playfields became littered with numerous "under-playfield transistors", Gottlieb® opted to merge some of these transistors into a transistor driver board. The transistor driver board started to appear on Gottlieb® games nearly midway through the System 80B platform, with the game Victory.
 

The sound S16 and S32 signals are also repurposed lamp outputs. For instance, Haunted House and Black Hole both repurpose L9 to S16. Robo-War repurposes lamp 4 to S16. Note that S16 is not consistently implemented across the System 80 family. Note also that references to the usage of S32 are difficult to find.
 
[[File:Sys80 driver screws.JPG|300px|thumb|left|Nuts / Screws Which Secure the 2N3055s Collector to Drive Line]]
[[File:System80-2N3055.jpg ‎|300px|thumb|right|If the metal casing of the transistor is not "making" with the trace it is connected to, the solenoid will not fire.]] 
Make certain to inspect and tighten the screws which secure the 2N3055 TO-3 transistors to the driver board. Specifically, the screws / nuts as marked in the pic. They tie the transistor cases (collector) to the respective solenoid drive lines. If these cases are not secured, the transistors will not function as intended.
 

====Remote Mounted Transistors====
[[File:UnderPFTransistor.jpg|300px|thumb|left|Under Playfield Transistor, with Emitter, Base, and Collector Labeled]]System 80 games have nine dedicated solenoid circuits on the driver board. To overcome this limitation, Gottlieb® added remote, high current transistors, mounted to brackets under the playfield. A lamp drive transistor is generally used to "pre-drive" the larger solenoid drive transistor. However, there are instances where a solenoid drive transistor is used to pre-drive a remotely mounted transistor. In later games, Gottlieb® Premier began to add (up to) three transistors on PCBs. These PCBs were mounted behind the game's lamp insert panel or on the side wall of the lower cabinet. While other games, such as Monte Carlo, have a large metal bracket installed under the playfield with 6 transistors installed, and a common ground on the collector of the metal bracket. With 80B games, the game's diagnostics will drive these transistors during solenoid test, otherwise, they are typically driven during lamp test.

On System 80 games, under playfield transistors were originally 2N5875s or 2N5879s. The failure rate of the original transistors tends to be rather high. Thirty years is a long time for a transistor of that technology. Should one fail, it can be replaced with one of its beefier siblings, a 2N5880, 2N5883 or 2N5884. An MJ2955 can also be used.

System 80B games used a mix of 2N5879 transistors and MJ2955 transistors to drive flash lamps and coils.
 

[[File:RemoteTransistors.jpg|300px|thumb|left|An image/schematic/explanation (click)]] 
A ground wire is always connected to the tip of the transistor (collector) and leads to ground. On System 80 games, this wire is green/yellow (Gottlieb® wire color code 54). On 80B games, ground wires are plain white with no trace (Gottlieb® wire color code 9). 
The "emitter" should be connected to the lug of the coil that has the non-banded side of the diode facing it (black-blue-blue in this picture). 
The "base" should be connected to the drive wire from the driver board (brown-red-red in this picture).
 

Note: Solenoids which use a remote mounted transistor cannot be enabled by temporarily grounding the pre-drive transistor's tab to ground. This test is typically performed to check the integrity of the wiring from the drive transistor to the solenoid. This test however does not confirm if the drive transistor is good or not. 

=====Remote Mounted Transistor Update=====
[[File:Remote transistor circuitry.png|left|thumb|300px|Gottlieb® Remote Transistor Circuit]]
During the run of Black Hole, Gottlieb® released a service bulletin recommending that the existing 10Kohm pullup resistor be changed to a 4.7Kohm resistor when changing from a 2N5875 to a 2N5879 or equivalent. Affected Black Hole games were marked serial number 6271 to 9160. However, there were several games prior to and after Black Hole, where a pullup resistor was never installed. And, don't always bank on the playfields installed in a game being original to the cabinet's serial number. Case in point is a recently acquired Black Hole where the main playfield had a factory pull up resistor for the ball release coil transistor, but the 3 coils on the [http://www.pinwiki.com/wiki/index.php?title=Black_Hole#Pull_Up_Resistors_Added_to_Remote_Transistors_.28Centrally_Located.29_on_Lower_Playfield lower playfield which use remote transistors] did not have the pull resistors added.
 

[[File:Pullup circuitry.png|left|thumb|300px|Gottlieb® Remote Transistor Circuit w/ Pull Up Resistor Upgrade]] 
It is highly recommended to add this resistor. This upgrade will decrease the chances of particular solenoids, which use a remote mounted transistor, from locking on when the game is powered up. The 4.7K resistor is soldered to the base of the remote mounted transistor, and then tied to the 24vdc solenoid bus.
 

====Power On "Thunk"====
Due to the driver board design, certain solenoids and / or relays can pulse briefly as soon as a game is turned on. To rectify the issue, please refer to the [[#Power_on_.22Thunk.22|Power on Thunk]] section above. This applies to potentially all System 80/80A/80B games, where the solenoid / relay signal passes through one of the 74175 chips on the driver board.
 

====Correcting Solenoid Problems====
Gottlieb's implementation to control solenoids was, at a top level, identical to every other game manufacturer. Power is present at the coil, sometimes routed through the "Game Over" relay. A path to ground is switched on by a transistor which is enabled by upstream TTL logic. For the System 80 platform, this TTL logic is located on the MPU board. Signals are conveyed from the MPU to the driver board via the A1J4-to-A3J1 wire harness. These signals directly switch a path to ground on for one of the 9 designed-in solenoid circuits.

As noted above, to accommodate game implementations needing more than 9 solenoids, Gottlieb repurposed some of the lamp driver circuits, driving 2N5875 (generally) transistors either screwed to the bottom of the playfield, or located on dedicated transistor boards.

Solenoid problems can be divided into two simple categories, solenoids that do not engage and solenoids that are "locked on". Correcting these two situations is discussed below.

=====Solenoid Doesn't Turn On=====

First, note that not all solenoids are always tested by the built in solenoid diagnostics. The first example of this is the coin counter solenoids (numbered 3, 4, and 7). To avoid artificially incrementing the coin drop counters, these coils are not pulsed. Other coils may be pulsed during lamp test. This is most often the case with System 80B games, using repurposed lamp driver circuits.

:Problem Determination Procedure

<ol>
<li>
With the game turned on and a game started, use a DMM to measure for coil power at the coil lug (generally either 24 or 38VDC). Power should be present at both lugs of the coil. If present on the coil lug attached to the banded side of the diode and not present at the coil lug attached to the non-banded side of the diode, then the coil winding or it's attachment to one of the coil lugs is open.
</li>
<li>
Next, test paths to ground for the coil. Attach a wire with clip leads to game ground. Any green wire with yellow stripe will work fine. First, BRIEFLY touch the other end of the wire to the non-banded side of the coil lug. The coil should pull in. If it does not, then either the coil winding is open or the coil wire is not securely attached to the coil lug. Next, identify the driver board transistor that switches ground for the solenoid in question. BRIEFLY touch the other end of the wire to the tab (MPS-U45 or 2N6043) or case (2N3055) of that transistor. The solenoid should pull in. If it does, this proves the path from the coil to the transistor, but doesn't prove anything about the transistor. If it doesn't pull in, then there is a break in continuity between the transistor and the coil. Likely suspects are the connector pins, the IDC connection of the wire to the connector, and the actual wire itself.
</li>
<li>
At this point in the process, we know that the coil has power, and the path to ground via the transistor is valid. The next step is to test the actual transistor.
</li>
</ol>

:::Testing an MPS-U45 (or NDS-U45) or an MPS-A13 transistor
:::*Set the DMM to diode check
:::*Place the red lead on the center leg
:::*Place the black lead on each of the flanking legs in turn
:::*A measurement between .5 and .7 should be displayed for one of the flanking legs.
:::*A measurement between 1.2 and 1.4 should be displayed for the other flanking leg.
:::*Readings outside of these ranges (generally dead shorts, sometimes opens) indicate the part has failed.

:::Testing a 2N6043 transistor
:::*Set the DMM to diode check
:::*Place the black lead on the center leg
:::*Place the red lead on each of the flanking legs in turn
:::*A measurement between .5 and .7 should be displayed for each flanking leg
:::*Readings outside of this range (generally dead shorts) indicate the part has failed.

[[File:TO-3Case2N3055.jpg|300px|thumb|right|Emitter, Base, and Collector parts of a TO-3 form transistor, like the 2N3055. Note that the emitter and the base pins are closer to one end of the TO-3 case.]]
:::Testing a 2N3055 transistor
:::*Set the DMM to diode check.
:::*Place the black lead on the metal casing of the transistor.
:::*Place the red lead on each of the legs in turn.
:::*A measurement between .5 and .7 should be displayed for one of the legs.
:::*A measurement of "null" (no reading) should be displayed for the other leg.
:::*Place the red lead on the "base" lead of the transistor.
:::*Place the black lead on the other lead of the transistor (the "emitter").
:::*A measurement between .5 and .7 should be displayed.
:::*Place the black lead on the case of the transistor (the "collector").
:::*A measurement between .5 and .7 should be displayed.
:::*Readings outside of these ranges (generally dead shorts, sometimes opens) indicate the part has failed.
 
<ol start =4>
<li>
Test the output signal from the MPU at the driver board. This test completes the test of the driver board circuitry. If this test doesn't identify a problem, then the problem must lie upstream with the inter-board harness or on the MPU board itself. With a logic probe, and the game in solenoid test, probe the following points for solenoids 1 through 9. 1 - non-banded side of CR6, 2 - R53, 3 - non-banded side of CR2, 4 - non-banded side of CR4, 5 - R56, 6 - R59, 7 - non-banded side of CR4, 8 non-banded side of CR1, 9 - non-banded side of CR5. With the game in Solenoid test, each solenoid should be pulsed in order, with the pulse easily detectable with a logic probe on the appropriate spot. Note that the coin counter solenoids will not be pulsed in test, and games that don't use every solenoid won't pulse unused solenoid circuits. Consult the manual for solenoid numbering for a particular game.
</li>
<li>
Test the output signal of the TTL circuitry on the MPU. Solenoids 1 through 9 are all enabled via signals from Z29 and Z30 on the MPU board. Both ICs are 7416s. Z29 pins 2, 4, 10, and 12 drive solenoids 1 through 4 respectively. Z30 pins 2, 4, 6, 10 and 12 drive solenoids 5, 6, 8, 9, and 7 respectively (note the order is not strictly ascending). If the output signal on the MPU is present, but the signal is not present on the driver board, then the problem is probably the inter-board connector.
</li>
</ol>

=====Solenoid Locked On=====

A solenoid (or flasher) that is "locked on" is caused by coil power having a continuous path to ground. Remember, coil power is always present at the coil when a game is started and the game over relay is powered (for System 80/80A/80B games). 99.9% of the time, this continuous path to ground is caused by a shorted drive transistor; either an under-playfield transistor, a transistor on a transistor board, or a transistor on the driver board itself.

Generally, a locked on coil will heat up, burn through the insulation on the coil windings, and cause direct shorts between windings. This effectively reduces the length of the wire and hence, the resistance. Once the resistance is reduced to less than 2 ohms or so, the continuous current through the transistor and the coil cause both to be irreparably damaged. For this reason, if you find a transistor shorted, check the associated coil. Likewise, if you find a coil shorted, or with significantly reduced resistance (ohms), check the associated transistor.

Some solenoid driver circuits, like solenoid 8 that uses a 2N3055, are "pre-driven" by an MPS-U45 (or NDS-U45). Be sure to test the associated pre-driver transistor too.

===Lamp problems===
Lamp problems are common with most any pinball machine, and Gottlieb® System 80/A/B games are no exception.

For controlled and GI lamps, Gottlieb® System 80/A/B games use either a #44 or #47 lamp. The choice of which lamp to use is the preference of the game owner.

For games with flash lamps, a #67 bulb is used.

It is highly recommended '''not''' to replace or remove lamps with the power to the game on. There are primarily two reasons for this.
#Some lamp sockets must have their mounting brackets bent back to access the bulb for replacement. In turn, the potential of inadvertently shorting one lamp socket to another is possible.
#Lamps are constructed of an equal balance of glass and conductive metal. If a bulb slips out of one's grasp when trying to remove or install with the power on, there are many areas in the bottom of the cabinet, where the metal of the bulb can short across. A short across other circuits could potentially lead to other unplanned or otherwise unnecessary repairs needed to perform. 
So in short, change or remove bulbs with the game's power off, just to be safe. 
All System 80 games have three separate lamp circuits, and some have a fourth. The circuits are comprised of:
*General illumination for the backbox
*General illumination for the playfield
*Controlled lamps for primarily the playfield, although, there can be four controlled lamps located in the backbox (shoot again, high score game to date, tilt, and game over), depending on the era of the game.
*Auxiliary lamps used for effect, such as chaser lamps used around the backglass border of Mars God of War and Black Hole. Auxiliary lamps are not used on all games. Jump to the [[#Auxiliary_Lamp_Driver_Boards | Auxiliary Lamp Board section]] to see what games use auxiliary lamps.

Below are several approaches used to determine the source of a lamp problem, and how it can be resolved. 

====Bad Bulbs====
The first thing when troubleshooting lamp problems, and this may seem blatantly obvious, but determine whether the lamp is good or not. The bulk of all lamp problems are simply burned out light bulbs. Always try a known good bulb as the solution first. Don't rely on the bulb being brand new either. The ratio of brand new, bad bulbs is slim, but there is that chance a new bulb is not good. 

[[File:Dying battery.JPG|thumb|left|300px|Making certain an old 9v battery is putting out an acceptable lower voltage]]
[[File:Testing bulb.JPG|thumb|right|300px|Testing a 6v bulb with a dying 9v battery]] 
The bulbs used in a System 80/A/B game are powered by ~6 volts, (the exception is the bulbs powered for the lower [[#Replacing_Black_Hole_Lower_Playfield_Illumination_Lamps_with_.2344_Lamps | playfield illumination on Black Hole and Haunted House]]). A great way to quickly test a bulb is to use a dying 9v battery. Don't use a fresh 9v battery, or you will shorten the life of the bulb. Find a battery that is roughly putting out 7v - 8.25v. An old battery from a smoke detector works pretty well.
 

Place the tip of the bulb on one of the battery terminals, and cock the outer metal casing of the bulb to touch the other terminal. Orientation of the bulb with regards to the positive and negative terminals does not make a difference in this case. Do not hold the bulb across the battery terminals for very long. Just long enough to determine if the bulb's filament is lighting or not. 

You may also use a known working socket to test bulbs in...but that requires the game to be on while testing...which always presents some risk and is not recommended. However, if there is no other option but to use a known good socket for testing bulbs, the preferred method is to use a socket located in the backbox lamp insert panel. This unfortunately does not pertain to 65% of the System 80B games, because a fluorescent lamp was used for backbox illumination for them. 

Games that have not been played in a long time develop a film of corrosion between the lamp "nipple" and the lamp socket which prevents conductivity. Simply removing the lamp and scratching the nipple with something abrasive (like rubbing it on the lockdown bar receiver) may fix many "lamp out" problems. In some cases, a light socket cleaning stick (available from the Pinball Resource [http://www.pbresource.com/tools.html here]) may be useful for cleaning the lamp socket. Gottlieb® lamp sockets are comparatively beefy and do not fail often.
 

====Lamp Power Issues====
Next, make certain there is power at the lamp socket. The game will have to be turned on for the following procedures. 

=====General Illumination Lamp Power Issues=====
GI lamps are powered by ~6VAC. When testing a GI lamp socket for power, each lead of the DMM (now set in AC mode) will be placed on the two leads of the lamp socket. If there isn't power at the lamp socket, suspect a bad fuse first. Keep in mind that the playfield GI and backbox GI for System 80, 80A, and a few 80B games (the first 3 80B games and the last 2), have two separate fuses located on the transformer board in the bottom of the cabinet. These are typically higher amperage rated fast-blo fuses. The backbox GI on a System 80 game is always on when the game is turned on. If the backbox GI fuse is good, and no backbox lights are lit, the inline connection which feeds the GI could possibly be bad. Unfortunately, this connection is not standard from game to game. 

[[File:GottliebSystem80TiltRelayAnnotated.jpg|thumb|left|300px|Gottlieb® System 80 Tilt Relay with GI Lamps/Tilt Lamp Make-Break Switch Highlighted. This tilt relay is from a Gottlieb® Spiderman]] 
The playfield GI is always powered on too, except when the game is in tilt mode. If the game was not tilted and /or the tilt switches are not stuck closed, check the switch stack on the tilt relay. These switches can sometimes get bent or misaligned. If the playfield GI fuse is good and the tilt relay switches are good, the inline connections may be suspect.
 

If the fuse to a particular GI circuit is bad, and continues to blow every time a new fuse is installed, a short is probably causing the issue. A shorted lamp GI circuit is probably the worst and most difficult lamp related issue to resolve. In most cases, the GI power lines are uninsulated wiring, which make them susceptible to shorted circuits. First, determine if the GI short originates on the backbox lamp insert or on the playfield. GI shorts on the playfield are typically more common than backbox lamp insert shorts. Pop bumper lamps are generally not CPU controlled, and are included in the playfield GI string (some System 80B games are the exception, [http://www.ipdb.org/machine.cgi?id=1975 RoboWar] being an example). Also, depending on the game, star rollover lamps and kickout hole lamps are sometimes part of the playfield GI circuit. Consult the game manual for these particulars.

Although it can be a pain and time consuming, the best approach is to remove all of the bulbs in the associated shorted GI string. In removing all of the bulbs, we are trying to isolate whether the problem is a bad, defective bulb, or one of the GI power lines is shorting.

=====Controlled Lamp Power Issues=====
Controlled lamps are powered by ~6VDC. When testing a controlled lamp socket, the red lead of the DMM (now set in DC mode) will be placed on the lamp socket mounting bracket. The bare wire soldered to the lamp socket's mounting bracket is the power bus not the ground bus, so be careful. The black lead of the DMM will be placed on ground. If working under the playfield, the ground plate in the bottom of the cabinet is a good place to connect to ground. If working in the backbox, find where one of the green wires with a yellow trace is screwed to the metalwork, and place the lead on it. Depending on the game, System 80 side rails, lockdown bar assemblies, and other associated trim metalwork, except the coin door, were not grounded from the factory like Bally, Williams, and Stern. Therefore, using any of these as a ground reference is not recommended. Gottlieb® did start grounding the metalwork at the start of the System 80A platform.

If there isn't any power at the lamp socket, suspect a bad fuse first. The controlled lamp circuit has a separate fuse on the transformer board, and is normally a 5 amp slo-blo fuse. If the [http://www.pinwiki.com/wiki/index.php?title=General#Testing_fuses fuse tests fine], there is a separate set of switch leaves on the tilt relay, which pass the controlled lamp power to the playfield lamps. Inspect and adjust these switches if necessary. If the controlled lamp fuse and the switches on the tilt relay both test good, there may be an issue with the source power connection to the rectified DC circuit on the game transformer board. Unfortunately, System 80/80A/80B used different connector designations for controlled lamp source power for different games. Consult the game manual / schematics to find the source of 6VDC on the transformer board power supply.

If the fuse for the controlled lamps is bad, and continues to blow after a new fuse is installed, suspect a bad controlled lamp bridge rectifier. The lamp bridge rectifier is located on the transformer board. Please see the [http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Bridge_Rectifier Testing a Bridge Rectifier] portion of the PinWiki guides. Before testing the bridge rectifier, try to isolate it as much as possible. By isolating it, this will minimize the possibly skewed readings caused by attached devices (lamps and the power transformer). Two key things to do would be to remove the lines which connect the bridge to the playfield and backbox lights, and remove the controlled lamp fuse. Keep in mind that a bridge rectifier can fail in such a way where it may not blow the controlled lamp fuse. Although, a failed bridge blowing a fuse is a tad more common than not.

If all of the above tests good, there may be a short on the controlled lamp bus line. This is not a very common occurrence, but it can happen. Inspect the underside of the playfield for any wires or brackets touching the controlled lamp bus line, which shouldn't be touching.

====Bad Lamp Sockets====
Third, determine if the lamp socket is good. Some games have been through the wringer, and the sockets didn't hold up too well due to abuse, a damp environment, or other various reasons. Start by turning the '''power to the game off'''. If the socket has some corrosion, try using a lamp socket cleaning tool first. If a lamp socket cleaning tool is not available, a small wire brush used for cleaning copper fittings, a rolled up piece of 220 grit sandpaper, or a Dremel tool with a small wire brush attachment can all be used. After the socket has been cleaned, place the bulb in the socket for the following procedures. 

If testing a '''GI lamp''' socket, use the dying 9v battery trick again. Remove the fuse of the particular GI circuit which the lamp socket being tested is located. Connect the terminals of the 9v battery to the bulb socket with alligator clip leads. Be careful not to short the alligator clips to each other at the battery's terminals. Equally be very careful not to short the clip leads to an adjacent switch on the pinball machine, or anything else for that matter. One clip will connect to one side of the socket, and the other lead will go to the other side of the socket. '''DO NOT ALLOW THE BATTERY TO STAY CONNECTED VERY LONG'''. Since this is a GI lamp circuit, other lamps in the string will be powered by the battery. If the battery is connected to the string for too long, the battery will start to get hot. The battery does not have enough power to light a string of bulbs for very long. The lamp may only glow dimly, but that is enough to determine if the socket is good or not. 

If testing a '''controlled lamp''' socket, remove all of the connector housings from the bottom of the driver board first (A3-J2/J3/J4). Then remove the fuse for the controlled lamp circuit. Clip one lead of the battery to the lamp socket mounting bracket and the other to the solder tab. The orientation of the negative and positive leads of the battery terminals makes no difference. Again, keep the battery connected just long enough to see if the lamp lights to determine whether the lamp socket is good or not. 

====Controlled Lamp Issues====
=====Lamp(s) Will Not Turn On=====
So, the bulb is good; the socket is good; there's power at the socket; and the lamp still won't light. Well, this occurrence can only really happen if there is a controlled lamp involved. If all three of the above things apply, it can only mean one thing - the bulb is not getting properly grounded, and will not turn on. The source of this problem may be due to several different issues. But, it is best to start at the bulb socket, and work backward towards the CPU board. 

Determine if the connector and wiring from the output of the driver board to the lamp socket is good. While the wires are usually solid, the single sided edge connectors are a frequent cause for loss of conductivity. Simply "buzzing" the connection from the lamp socket back to and onto the driver board may uncover the issue. With the power off, check the continuity between the solder tab of the lamp socket and the collector (right leg) of the associated lamp transistor. 

If there is continuity, it’s time to test the transistor. Transistors fail "open" (lamp never lights) and "shorted" (lamp is constantly on). A simple comparison of "diode check" readings between "same type" transistors on the driver board can identify failed transistors.

Testing an '''MPS-A13''' transistor.
#Set your DMM to diode test
#Place the '''red''' lead of your DMM on the center leg
#Place the '''black''' probe on left leg (viewing the component side of the board). That leg should read about 1.3
#Move the '''black''' probe to the right leg. That leg should read about .7
#Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

Testing an '''MPS-U45''' transistor (or '''NDS-U45''' or '''CEN-U45''' which are equivalents).
#Set your DMM to diode test
#Measure on the solder side of the board, with J5 and J6 oriented toward you
#Place the '''red''' lead of your DMM on the center leg
#Place the '''black''' probe on left leg. That leg should read about 1.3
#Move the '''black''' probe to the right leg. That leg should read about .7
#Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

[[File:ReplacingMPS-U45WithMPS-A13.jpg|300px|left|thumb|An NDS-U45 replaced by the less expensive MPS-A13. This replacement is advised ONLY if the transistor drives a single lamp.]] 
The System 80/80A/80B architecture does not utilize a lamp matrix. Controlled lamps are driven by individual transistors on the driver board, exactly like Gottlieb® System 1 games and Bally/Stern 6800 games. Driver board operation is pretty simple. The CPU places a signal on Logical Device lines 1 through 4 (LD1...LD4) and "strobes" the appropriate 74175 device select pin to latch the LDx values into the 74175 Quad FlipFlop's outputs. These outputs then drive the associated transistor(s) on, providing a path to ground for the lamp. That's all there is to it.

The transistors on the driver board are a mix of 2N6043s, MPS-U45s (or NDS-U45s), 2N3055s, and MPS-A13s. 2N6043s drive coils. Generally, the MPS-U45 transistors drive coils, pre-drive coils via remote mounted transistors and 2N3055s, or drive more than one lamp. The 2N3055s drive coils (in some cases, not all 3 of these are used in a game). The MPS-A13s generally drive a single lamp.

MPS-A13 transistors are still widely available and cheap. MPS-U45s are obsolete but may be replaced with CEN-U45 transistors [http://www.greatplainselectronics.com/search.asp?pg=1&stext=cen-u45&sprice=&stype=&scat= available from Great Plains Electronics] and Mouser. A much cheaper MPS-A13 may sometimes be substituted for the less common and more expensive MPS-U45, as shown in the pic at left for Q22. Although this will work, you must ensure that the transistor is driving only a single lamp. This obviously limits the "portability" of the driver board. If Q22 were used to switch anything other than a single lamp on, it will be destroyed. Substitute with caution.

2N6043 transistors used on the driver board are still available but becoming pricey. 2N6043s can be replaced by a TIP-102. 

'''Note:''' A nice convention Gottlieb® used with System 80 games is that lamp "n" is driven by transistor "n+1" on the driver board. This is always true. 

If the transistor tests fine, a gate on the 74175 may be bad, which is rare but does happen. Use a logic probe on the input and output of the associated lamp gate to check definitively. Again, comparing the signal between different drive pins can help identify a failed driver circuit. 74175s can easily and reliably be tested using the procedure in the "General for all games" section, [http://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit here].

If more than one controlled lamp is not lighting, check the game’s manual / schematics to see if the bulbs are related in some way.
*When four lamps are not lighting, it may appear that the 74175 which controls the lamp transistors is at fault. This can happen, but the more commonly related issue is that the device select signal for a particular 74175 is lost between the CPU and driver board. This can be due to a bad connection at A1J4 or A3J1. See the chart below for the lamp device select signal path.
*When a whole group of lamps fail to light, review the schematics to see if the lamp transistors share a common ground path. Again, poor connections at the driver board, or the path to ground (generally green with yellow tracer or solid white wire) on the bottom board ground strap may be the root cause.

If the connections, associated 74175, and lamp transistors are all correct, the circuitry on the CPU board is probably at fault. Again, using a logic probe to determine which component on the CPU board has failed is the best course of action.

{| class="wikitable" style="margin: 1em auto 1em auto;"
! Device Select 
! CPU Connector 
! Driver Input 
! Driver Quad Flip-Flop (74175) 
! Transistor #s 
! Lamp #s 
|-
| DS1 || <center>A1J4-C</center> || <center>A3J1-C</center> || <center>Z1</center> || <center>Q1-Q4</center> ||  Game Over relay, Tilt relay, coin lockout, L3 
|-
| DS2 || <center>A1J4-3</center> || <center>A3J1-3</center> || <center>Z2</center> || <center>Q5-Q8</center> ||  L4-L7
|-
| DS3 || <center>A1J4-E</center> || <center>A3J1-E</center> || <center>Z3</center> || <center>Q9-Q12</center> ||  L8, sound 16, L10, L11
|-
| DS4 || <center>A1J4-D</center> || <center>A3J1-D</center> || <center>Z4</center> || <center>Q13-Q16</center> ||  L12-L15
|-
| DS5 || <center>A1J4-H</center> || <center>A3J1-H</center> || <center>Z5</center> || <center>Q17-Q20</center> ||  L16-L19
|-
| DS6 || <center>A1J4-F</center> || <center>A3J1-F</center> || <center>Z6</center> || <center>Q21-Q24</center> ||  L20-L23
|-
| DS7 || <center>A1J4-K</center> || <center>A3J1-K</center> || <center>Z7</center> || <center>Q33-Q36</center> ||  L24-L27
|-
| DS8 || <center>A1J4-J</center> || <center>A3J1-J</center> || <center>Z8</center> || <center>Q37-Q40</center> ||  L28-L31
|-
| DS9 || <center>A1J4-M</center> || <center>A3J1-M</center> || <center>Z9</center> || <center>Q41-Q44</center> ||  L32-L35
|-
| DS10 || <center>A1J4-L</center> || <center>A3J1-L</center> || <center>Z10</center> || <center>Q41-Q44</center> ||  L36-L39
|-
| DS11 || <center>A1J4-N</center> || <center>A3J1-N</center> || <center>Z11</center> || <center>Q41-Q44</center> ||  L40-L43
|-
| DS12 || <center>A1J4-P</center> || <center>A3J1-P</center> || <center>Z12*</center> || <center> Q45-Q48 & Q49-Q52 </center> ||  L44-L47 & L48-L51 (inverse of L44-L47) 
|}

*Z12 not only outputs four lamp signals like all the other 11 74175s, but it also outputs four inverted lamp signals. These signals are typically used for lamps located on opposite sides of the playfield which alternate on / off between each other.
 

=====Lamp(s) Will Not Turn Off=====
If a single lamp is involved, or only a handful of lamps with different lamp device select signals, suspect the lamps' associated drive transistors. If a group of four lamps will not turn off, and they are all controlled by the same 74175, suspect the associated 74175 or the device select for that 74175 ("DS" on the schematics). If numerous groups of four lamps will not turn off, suspect the associated 7404 on the CPU board.
*Z17 for DS1-DS5 device select signals or,
*Z24 for DS6-DS11 device select signals or,
*Z26 for DS12-DS16 device select signals.
If the lamps involved originate from more than one group of device select signals, suspect the 74154 at Z25 or, backing up one more step, the 6532 RIOT at U5.
 

===Flash Lamps===
Flash lamps are #67 powered by the 24VDC solenoid bus. They are controlled like any of the coils that have a under-playfield transistor. To step down 24V to a more lamp-friendly 13V, the power is routed through a single 4 ohm 7 watt resistor for powering paired flash lamps wired in parallel. An 8 ohm 5 watt resistor is used for powering single flash lamps.

On early 80B games, the power resistors are mounted to a small bakelite board under the playfield (up to 4), and the transistors are mounted to a bracket (up to 6). On later games, starting with Arena, new PCBs were introduced that had the transistor, power resistor, and 4.7K pullup resistor all on the same board (up to 3).

If lamps are locked on, or won't work, the remote mounted transistors associated with them have failed. Generally, the pre-drive transistor on the driver board has also failed.

Under-playfield flash lamp transistors are 2N5879s or MJ2955s.

===Auxiliary Lamp Problems===

[[File:GTB Aux Board Headers.JPG|thumb|left|300px|Reflowed Header Pins on Auxiliary Lamp Driver Board]] 
For issues with lamps controlled by the auxiliary lamp driver board, follow the troubleshooting section for controlled lamps [[Gottlieb_System_80#Controlled_Lamp_Issues | above]]. Additionally, make certain that +5vdc and ground are present on the auxiliary driver board. If either are missing, the potential for cracked header connections is possible. Remove the existing solder from the header connections, and resolder the header pins.
 

====Unconventional Lamps====
System 80B games added quite a few special lighting effects. Gottlieb® never used software when hardware would do. This is probably harkens back to their electromechanical days. So, there are usually some creative, different ways used to control lamps. For instance:

<ul>
<li> Monte Carlo and Spring Break have Auxiliary Lamp Driver boards where power to a bunch of #44 lamps is switched by a relay.
<li> Genesis drives #67 lamps with an auxiliary power board. Power to this board is controlled via a relay that turns itself to activate the "reveal"; this relay is activated by a lamp driver, but the relay will keep itself on until one revolution of the reveal gimmick is done.
<li> Spring Break has eight #44 lamps controlled by one relay; the relay is controlled with a lamp driver.
</ul>

Diagnosing these is generally the same as other lamps, but first, understand the peculiar arrangement for the game in question.

===Switch problems===

==== Switch Matrix Operation ====

The Gottlieb System 80 switch matrix is implemented via the 6532 RIOT (RAM, I/O, Timer) at U4, strobe ICs at Z11 and Z12 (7404), return ICs at Z13 and Z14 (7400), and DIP switch "read enables" at Z15. The switch matrix simply provides a TTL "low" pulse on a single switch matrix column, then listens for a "low" return on the switch rows. Closed switches complete the circuit and enable a switch matrix return. Switch returns are processed then the next column is strobed. The game software "debounces" all switches to accommodate less than electrically and mechanically perfect switches.

==== Common Switch Matrix Faults ====

===== Isolating Switch Problems to the MPU or the Game Wiring =====

Since Gottlieb uniquely used edge connectors instead of more common header pins, isolating switch matrix issues to either the MPU or to the game wiring is not quite as easy. However, "jumping" from a switch column to a switch row is possible using the same technique.

*Place the game into switch test
*Using a short length of wire, short each column drive to each row return, one at a time
*A single switch closure should be shown as each connection is made.

If a single switch closure is shown for each and every connection made, then the MPU circuitry is probably undamaged, and the playfield wiring, switches, and diodes should be examined. If a switch closure isn't registered, or more than one switch closure is reported, then the MPU circuitry is damaged.

===== MPU Switch Matrix Issues =====

====== Blown Switch Matrix ICs ======

[[File:GottliebStackedSwitch.jpg|thumb|left|300px|The thin strip of "fish paper" physically isolating the flipper EOS switch and the "lane change" switch is all that prevents certain destruction of switch matric chips. Image courtesy of Russell McIntyre.]]
[[File:System80SwitchMatrixICs.jpg|thumb|right|400px|Identifying the System 80 MPU switch matrix ICs. Z15 is just below Z11/Z12.]]
[[File:System80MPUBlownZ13.jpg|thumb|left|300px|Diode testing Z13 uncovers a shorted IC caused by shorting HV to the switch matrix wiring.]] 
The most prevalent reason for switch matrix failures is shorting high voltage (i.e. coil voltage) to the switch matrix. As always, it's inadvisable to work on the game with the power on. Sometimes, "fish paper" designed to isolate switch blades from higher voltage conductors becomes displaced, shorting high voltage to the switch matrix, and damaging some/all of the switch matrix ICs. Examples of such a switch are the kicking target under the upper playfield in Haunted House and the "lane change" stacked switch on the right flipper of games like Mars God of War, Rock, Genesis, Gold Wings, and Spring Break.

A quick check of Z11 through Z15 using the [http://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit diode test] will reveal failed ICs easily. An example is pictured at right.

Using this same diode test on U4, comparing the results to U5 and U6, may help to identify a failed RIOT.
 

====== Alkaline Damaged Connectors ======

Playfield switch wiring is connected to MPU edge connector J6, which is sometimes directly below, but at the very least in close proximity, of the OEM NiCad battery. These batteries frequently leak their corrosive contents onto the board, affecting nearby connectors, including the switch matrix connectors at J6 (playfield) and J5 (cabinet). Close examination of the friction pins in the connector as well as the copper traces at the edge connector may reveal alkaline corrosion impacting proper switch matrix operation.

===== Playfield Switch Matrix Issues =====

Once the switch matrix issue has been isolated to the playfield, follow the tips listed in the [http://www.pinwiki.com/wiki/index.php?title=General#The_Switch_Matrix Switch Matrix Diagnosis] section.

One additional item to note is that Gottlieb did not attach isolation diodes directly to switches. Instead, isolation diodes are collected on "diode boards" which are screwed to the playfield underside or the cabinet bottom.

===Display Problems===
The blue Futaba display glasses used by Gottlieb® System 1 and 80 machines are a fairly reliable, long-lasting display. Although, they can and do still fail. It's just a matter of diagnosing the symptoms of a failed display. 

Display problems can primarily be classified into the following categories: 
#Power problems
#Display glass failure
#Data problems
#Tired displays

[[File:Gtb sys80 displays.png‎|thumb|550px|left|Gottlieb® System 80 Display Diagram]]
[[File:Gtb sys80A displays.png‎|thumb|550px|left|Gottlieb® System 80A Display Diagram]]
 

====Display Power Problems====

Before even attempting to work on System 80/80A/80B displays, there are two caveats to heed. First and foremost, the displays function due to the necessity of several voltages, including high voltage. '''IF YOU ARE UNCOMFORTABLE WORKING ON HIGH VOLTAGE CIRCUITS, THEN DO NOT WORK ON THESE DISPLAYS!''' High voltage can hurt or even kill you. If you don't feel comfortable working around this type of scenario, then hire a professional to do the work. Secondly, any time a display connector needs to be disconnected, '''DO NOT REMOVE ANY DISPLAY RELATED CONNECTOR WITH THE POWER ON!''' This goes for the connectors located directly at the display, connectors A1J2 and A1J3 on the CPU board, A2J3 on the power supply board, and A7J3 / A7P3 (early System 80 up to Mars God of War), A10J1 / A10P1 (when used), A12J4 / A12P4 (Black Hole and after), or A10J7 / A10P7 (when used) from the transformer. Removing connectors with the power on can damage the display, the CPU board, and / or you. Sorry to "yell", but it is extremely important to stress the above two statements. Now that this is out of the way, let's move on. 

As stated above, the displays need several sources of voltage to function properly. The display voltages used are broken down by the type of display: +60VDC and 5VAC with a positive 8VDC offset are used for the 6-digit displays; +42VDC, +5VDC logic (for the 7432 chip - Z1), and 3VAC with a positive 4VDC offset are used for the 4-digit status display. When using a 6 digit display with DI513 Dionics chips, +5VDC is necessary for RP1 and RP2, both 8.2K resistor networks. Likewise, 7 digit displays also have a 7432 chip on them, and +5VDC is needed for them too. If any of the above voltages are missing, the display will never light. 

Prior to plugging in and turning the game on for the very first time, it is a good practice to check all of the fuse values located on the transformer board first. There is a 1/4 amp slo-blo fuse used for the display voltage, which is located on the transformer board in the bottom of the cabinet. With the game unplugged from the wall outlet, remove the fuse from its fuse holder. When checking fuses, never "eyeball" a fuse. Your eyes may tell you that the fuse is good, but your eyes can fool you. Use a digital multi-meter (DMM) or a continuity tester to check fuses. Put each lead of DMM on opposite ends of the fuse. A tone should be heard. If not, the fuse is bad, and should be replaced with the same value. Fuses are used to protect equipment, the surroundings, and you. Installing fuse values with higher ratings is very dangerous. '''DO NOT USE A FUSE RATED AT A HIGHER RECOMMENDED VALUE!''' If the existing fuse is blown, it may not necessarily mean there is a problem. Fuses do get stressed, and sometimes just fail. However, there is more than likely a problem somewhere in the display power train. 

With the game still unplugged, the next course of action is to place connector A2J1 on the power supply. A2P1 is the bottom connection on the power supply, and receives all voltages directly from the transformers and a single ground from the ground strip. Once A2J1 is connected, remove any other connections from the power supply (A2J2 and A2J3). All voltages should be tested before any boards or displays are connected to them. 

[[File:Gtb_sys80_psu_A2J3_highli.JPG|left|thumb|300px|System 1 Power Supply with A2J3 highlighted]] 
At this point, plug the game in, and turn it on. Using a DMM or volt meter, check all of the voltages at A2P3. For the +60VDC (A2P3-1) and +42VDC (A2P3-3), any ground connection can be used as a reference. The +42VDC is derived from the +60VDC. If there is +60VDC, but not +42VDC, The 18v CR6 zener diode or the R5 resistor may have failed. 

If the two high voltages test all right, it's time to check the offset voltages. The offset voltages are +5VDC (A2P1-6) and +8VDC (A2P1-9). Use any ground connection as a ground reference to test these voltages. 

If displays are not lighting, but either the +42VDC is present on the display (status display) or the +60VDC is present on the 6 digit or 7 digit displays, check for the presence of AC voltage used to power the display filament. Do not use ground as a reference when measuring these voltages, as they are AC. Measurements must be taken from the send and return lines. If the AC voltage is missing, check the in-line connection at A7J3 / A7P3 (early System 80 up to Mars God of War) or A12J4 / A12P4 (Black Hole and after). Also, some games have more connectors which pass the AC voltages. These additional connectors are A10J7 / A10P7 or A10J1 / A10P1. Check the voltages on the input and output of the connector to see if fatigued connectors are the source of the voltage loss. 

If all the display voltages are satisfactory, it is time to move onto the next step of visually inspecting the display boards for obvious defects.
 

=====What is the DC Offset Voltage?=====
[[File:ACSineWave.jpg|left|thumb|300px|Representation of AC voltage with and without a DC offset component. Note the red sine wave is shifted "up" by the DC component.]]
[[File:DCOffsetClip.jpg|right|thumb|300px|A snippet from a typical System 80 schematic showing "DC offset" voltages connected to the center tap of the transformer secondary where AC filament voltages originate.]] 
Futaba displays as used in Gottlieb System 1 and System 80 games require AC power that is "offset" by a specific DC voltage; 8VDC for the 6/7 digit displays, 5VDC for the 4-digit credit/match display. The DC component of the AC voltage raises the AC sine wave by that DC voltage. If the offset voltage is missing, inconsistent or wavy displays will result.
 

====Display Glass Failure====
[[File:Good display.JPG|300px|thumb|left|Display with a good display glass]]
[[File:NippleGuard.jpg|300px|thumb|right|A cheap and easy way to protect your nipples]] 
The simplest and easiest problem to identify is display glass failure. All of the 6 digit displays used by Gottlieb® System 80, and 7 digit displays used by System 80A games will have a black "blotch", for lack of a better term, in the upper left and lower right corner of the glass. The 4-digit status display typically has only one black blotch. The evidence of a black blotch or blotches is good.

[[File:Bad sys1 display1.JPG|300px|thumb|left|Display with Broken Nipple on Back]] 
However, if there is a muted white blotch visible at the corners of the display, it means the display's "vacuum" has been compromised, either due to a cracked glass or broken nipple. If this is the case, the display glass can not be repaired and is useless.
 
A simple, cheap, and effective way to protect the glass nipple is to cut a ring of hose (garden hose was used in the picture at right), place it around the nipple, and then fill the ring with silicon caulk (preferred) or hot glue.
 

[[File:Broken top filament1.JPG|300px|thumb|left|Display with Broken Top Filament. Note that this is the Dionics chipset version of the display.]] 
The display filaments within the glass can also break. The end result will be segments with missing sections or "hot spots" when the display is powered. The "hot spots" are caused by the "dangling", broken filament shorting to other good filaments. If a display filament breaks, do not use the display as shorted displays can damage other game components.
 

<center>
<gallery widths=300px heights=200px perrow=3 caption="Example Display with Failed Filament">
File:OpenCenterFilamentOFFAnnotated.jpg|<center>Another example of a broken filament. This one has broken and shorted to another part of the display.</center>
File:OpenCenterFilamentScoreOverall.jpg|<center>The same display, showing a dark line across the center where the filament has failed.</center>
File:OpenCenterFilament.jpg|<center>Closeup of same display.</center>
</gallery>
</center>
 

Even though the glass itself is bad, the chips on the display board may still be good. So don't necessarily discount the display as being all bad. UDN6118A and 7432, (chip used on status display only), chips are getting more costly, and Dionics DI513s are very scarce. Since the display board is single sided, removal of the chips is quite easy. Plus, the display PCBs are no longer being made. The display board and / or chips may come in handy some time in the future.
 

====UDN6118 and Other Display Logic Chip Failures====
The majority of 4 and 6 digit displays utilize two UDN6118 "Vacuum Fluorescent Display Drivers". These ICs do not fail often. However, when they do fail shorted, they can affect the performance of the rest of the display set. 

[[File:TestingUDN6118AndUDN7180.jpg|300px|thumb|left|Test method for a UDN6118 or UDN7180 display driver. Colored dots represent DMM probe locations (red lead, black lead)]] 
UDN6118 driver ICs can be tested using a DMM. Click on the image at left for the procedure. 

<center>
<gallery widths=300px heights=200px perrow=2 caption="A Blown UDN6118 Display Driver">
File:UDN6118BlownTopSide.jpg|<center>Damage is hard to photograph, but the outline of the overheated chip core can be seen.</center>
File:UDN6118BlownBottomSide.jpg|<center>A much more visible image of the heat damage.</center>
</gallery>
</center>
 

=====Credit Display Segment Locked On=====
[[File:Gottlieb4DigitGlassSegmentCLockedOn.jpg|300px|thumb|left|A 4 digit display with segment "c" locked on, caused by a failed 7432 on the board]] Gottlieb 4 digit displays use two UDN6118s and a single 7432. The 7432 can fail in such a way as to cause segments to lock on, as shown in the picture at left showing segment "c" locked on.
 

====Display Data Problems====
When there are display issues, one first has to determine whether there is a problem with the display itself, the connectors involved, or the chips on the CPU board that control it. 

'''NOTE: Do not connect or disconnect the display connectors or connectors A1J2 and A1J3 on the MPU (right hand side) with the power on! Doing so WILL damage the MPU board display logic ICs.''' 

The following applies to System 80 and 80A displays. For information regarding the System 80B display board, scroll down to the end of this section. 

[[File:GottliebDisplaySegmentDigitOutAnnotated.jpg|340px|thumb|left|An excellent image to show both digit and segment problems. Note the red circles showing the same digit out on for players 1 and 3. Also note the yellow circles showing segment "g" out for players 1 and 2.]] 
'''Display Issue Isolated to a Single Display''' 
If the problem is only showing up one display, suspect that the connector at the display itself is problematic, or there is an issue on the display board. Problems on the display board can consist of a bad solder joint, a broken display lead from the display glass, or faults with the driver chips on the board (Sprague UDN6118 or Dionics DI513, if an old System 1 display is used). The exception is if only 4 displays and a status display are used, which is common to most System 80/80A games. In this display configuration, if there is a '''segment issue''' with the status display, there may be an issue with the segment drive chip on the CPU board. 

[[File:S80LockedHSegment.jpg|340px|thumb|left|An example of a display showing segment "h" locked on. The segment was locked on for both the player 3 and player 4 displays. This was caused by a failure of the 7404 at Z16. This picture was snapped right after pressing the diagnostic button on the coin door. The display should be blank.]] 
'''Display Issue With Multiple Displays''' 
If the problem shows up on two or more displays, suspect one of the two connectors on the CPU board (A1J2 or A1J3), one of the two connectors on the two displays (they are daisy-chained with an IDC connector), or the chips which control the display data on the CPU board. If there is a '''digit issue''', the issue will be present on '''player 1 and 3''' or '''player 2 and 4''' displays. If there is a '''segment issue''', the issue will be present on '''player 1 and 2''' or '''player 3 and 4''' displays, and the '''status display'''. If more than 4 scoring displays are used, on games such as Pink Panther, Black Hole, Haunted House, Devil's Dare, etc., consult the game manual for display digit and segment mapping.
 
 
[[File:Gtb sys80 displays.png‎|550px|left|Gottlieb® System 80 Display Diagram]]
[[File:Gtb sys80A displays.png‎|550px|right|Gottlieb® System 80A Display Diagram]]
 

The charts listed below, map out each signal to each specific display. The first chart maps the display digit information, while the second and third charts map the display segment information. This information only applies to games where 4 scoring displays and 1 status display are used, although digit group names have been added, if more displays are used. All of the charts apply to System 80 and 80A, but not 80B. 

<center>'''Display Digit Information'''
{| class="wikitable" style="margin: 1em auto 1em auto;"
!Digit Number
!Display(s)
!CPU Pin Connection
!Chip on CPU Board - Pin
|-
| D16 (80A only) || Players 1 & 3 (Group F) || A1J3-16 || Z26-8
|-
| D1 || Players 1 & 3 (Group D) || A1J3-1 || Z17-4
|-
| D2 || Players 1 & 3 (Group D) || A1J3-2 || Z17-6
|-
| D3 || Players 1 & 3 (Group D) || A1J3-3 || Z17-12
|-
| D4 || Players 1 & 3 (Group D) || A1J3-4 || Z17-10
|-
| D5 || Players 1 & 3 (Group D) || A1J3-5 || Z17-8
|-
| D6 || Players 1 & 3 (Group D) || A1J3-6 || Z24-2
|-
| D13 (80A only) || Players 2 & 4 (Group F) || A1J3-13 || Z26-4
|-
| D7 || Players 2 & 4 (Group E) || A1J3-7 || Z24-4
|-
| D8 || Players 2 & 4 (Group E) || A1J3-8 || Z24-6
|-
| D9 || Players 2 & 4 (Group E) || A1J3-9 || Z24-12
|-
| D10 || Players 2 & 4 (Group E) || A1J3-10 || Z24-10
|-
| D11 || Players 2 & 4 (Group E) || A1J3-11 || Z24-8
|-
| D12 || Players 2 & 4 (Group E) || A1J3-12|| Z26-2
|-
| D13 || Status (Group F) || A1J3-13 || Z26-4
|-
| D14 || Status (Group F) || A1J3-14 || Z26-6
|-
| D15 || Status (Group F) || A1J3-15 || Z26-10
|-
| D16 || Status (Group F) || A1J3-16 || Z26-8
|}
 

'''Display Segment Group A Information'''
{| class="wikitable" style="margin: 1em auto 1em auto;"
!Segment
!Display Group
!CPU Pin Connection
!Chip on CPU Board - Pin
|-
| a || Segment Group A || A1J2-1 || Z19-13
|-
| b || Segment Group A || A1J2-2 || Z19-12
|-
| c || Segment Group A || A1J2-3 || Z19-11
|-
| d || Segment Group A || A1J2-4 || Z19-10
|-
| e || Segment Group A || A1J2-5 || Z19-9
|-
| f || Segment Group A || A1J2-6 || Z19-15
|-
| g || Segment Group A || A1J2-7 || Z19-14
|-
| h || Segment Group A || A1J2-8 || Z16-12
|}
 

'''Display Segment Group B Information'''
{| class="wikitable" style="margin: 1em auto 1em auto;"
!Segment
!Display Group
!CPU Pin Connection
!Chip on CPU Board - Pin
|-
| a || Segment Group B || A1J2-9 || Z21-13
|-
| b || Segment Group B || A1J2-10 || Z21-12
|-
| c || Segment Group B || A1J2-11 || Z21-11
|-
| d || Segment Group B || A1J2-12 || Z21-10
|-
| e || Segment Group B || A1J2-13 || Z21-9
|-
| f || Segment Group B || A1J2-14 || Z21-15
|-
| g || Segment Group B || A1J2-15 || Z21-14
|-
| h || Segment Group B || A1J2-16 || Z16-10
|}

'''Display Segment Group C Information'''
{| class="wikitable" style="margin: 1em auto 1em auto;"
!Segment
!Display Group
!CPU Pin Connection
!Chip on CPU Board - Pin
|-
| a || Segment Group C || A1J2-17 || Z23-13
|-
| b || Segment Group C || A1J2-18 || Z23-12
|-
| c || Segment Group C || A1J2-19 || Z23-11
|-
| d || Segment Group C || A1J2-20 || Z23-10
|-
| e || Segment Group C || A1J2-21 || Z23-9
|-
| f || Segment Group C || A1J2-22 || Z23-15
|-
| g || Segment Group C || A1J2-23 || Z23-14
|-
| h || Segment Group C || A1J2-24 || Z17-2
|}
</center>

====System 80B Display Issues====

[[File:System80BDisplayDivotAnnotated.jpg|300px|thumb|left|A System 80B Display edge connector. One data conductor to the display was not "making" across the connection due to a corrosion "divot". This caused the entire display to remain blank. Reflowing the edge connector solder corrected the issue. Image courtesy of Chris Hibler.]]
[[File:GottliebEdgeConnectorDivots.jpg|300px|thumb|right|Another System 80B Display edge connector, this one with corrosion marks on it. The corrosion also caused the entire display to remain blank. Reflowing the edge connector solder corrected the issue. Image courtesy of Chris Hibler.]] 

System 80Bs displays are completely different how the digits and segments are decoded and driven. Unlike System 80 and 80A, where the decoder chips are located on the CPU board, the System 80B display has a single segment (U3) and two digit decoder chips (U1 & U2) located on the display board itself. Unfortunately, both of these chips (10941 & 10939 respectively) were a product of Rockwell International, and are not that prevalent. 

It has been observed that if any of the display data signals are missing between the CPU board and the 7417 inverters on the display board, the two displays will not illuminate at all. If voltages on the display board are within spec, it may be advantageous to check all of the data signal edge connector pins on the CPU board and the display board. If both the edge connector and the female connectors look good, use a logic probe to ensure signals are getting to the input side of both 7417 (or later 74LS367) inverters on the board. 

Keep in mind that the System 80B jumpers, that replace the 7448s at Z19 and Z21 on System 80 and 80A boards, can be a source of discontinuity due to cracked solder joints.

It has been observed that some of the earlier System 80B games are more prone to the display randomly being blank upon turning on the machine. Rock and Raven are the most common with this issue, however, the first three 80Bs, Chicago Cubs, Tag Team, and Bounty Hunter, are susceptible too. The best recourse is to repin both A1-J2 and A4-J1 / 1A4-J1.
 

====Rejuvenating Tired Displays====
[[File:System1-80DisplayBrightUp.jpg|300px|thumb|left|Rejuvenating tired System 1/80 displays]] 
System 80 displays, especially those that haven't been turned on for a long time, sometimes fade. These displays can be rejuvenated by applying voltage to the outside pins of the display glass. Note that voltage should be applied to the display glass pins, NOT the card edge pins. This process "burns" the impurities that accumulate on the filaments off.

In the picture at left, general illumination power (7VAC) from the lamp insert panel is being used to rejuvenate a display. 

Procedure: 
1. Turn the game off 
2. Remove the connector from the display 
3. Connect jumper clips from a voltage source to each of the outside pins of the display glass. Note that the lower the voltage applied, the longer the display can tolerate this "rejuvenation".     That is why some techs choose to use the lower GI AC voltage for this purpose. 
4. Power the game on for 1 minute. 
5. Disconnect the jumper wires and reconnect the display. 
6. Power on to test the display. 
7. If the display still isn't bright enough, repeat this process for 1 minute each time, until the display is satisfactorily bright. 

Note that if the display filaments, which run across the display horizontally begin to glow orange (or worse, white), too much voltage is being applied or the display has been connected too long. This risks burning one or more of the display filaments out and ruining the display. A cautious, 1 minute at a time, process is warranted.

Note also that one particular System 80 tech ("System 80, not just a job, it's an adventure") suggests that merely leaving the game powered on for 24 hours will accomplish the same rejuvenation.
 

====Display Does Not Light====
[[file:gottlieb-display-broken-legs.jpg|right|thumb|300px|Broken legs on display glass]]
If the glass of a 6 or 7-digit display does not light, but there are no white spots in the corners (white spots indicate bad glass), the outer-most legs on the glass may be broken. A magnifying glass may be necessary to inspect the pins since the gap in the breaks may be extremely small. The outer-most legs are responsible for supplying power to the glass, which is why the glass would not light in this situation.

These legs may be broken especially on displays that have a green or blue plastic filter covering them. These legs can get broken after someone presses down on the plastic cover of the display when pushing the display onto the PCB supports mounted on the light board in the backbox.

To repair, line up the two broken halves of the leg with needle-nose pliers, heat, and solder. If the solder isn't sticking, lightly sand back some of the black tarnish with fine sandpaper or a fiberglass eraser.

====System 80 Display Test 19 Never Starts====
System 80 games provide a display test (number 19). The test "walks" all digits, from 0 to 9, through all displays.

A failed 6532 RIOT at U5 can cause the game to appear dead, as if awaiting an input. The display test will never commence.

====Individual 6-digit Display Interferes With Other Displays====

Sometimes, a particular display can interfere with the operation of other 6-digit/4-digit displays no matter which game or player position it is plugged into. These symptoms can include:
* Causing digits to go missing on other displays
* Causing certain digits to dim significantly on other displays
* Causing certain digits to display garbage or non-numbers

The cause of these symptoms is a bad R1 resistor. When powered off, the resistor will give the correct reading. However, the resistor may fail when power is applied. The R1 resistor (10k ohm, 1/2 Watt, 5% resistor) may need to be replaced if the above symptoms are present.

====Individual 7-digit Display Causes Other Displays To Go Blank====
Sometimes, a particular display can interfere with the operation of the other 7-digit/4-digit displays no matter which game or player position it is plugged into.

If a particular display causes all other displays to go blank, the likely cause is a failure of the Z2 6118P chip, which drives the digits of the display. This chip can be replaced with the more commonly found UDN6118A chip. Also keep in mind that it's possible the 7448 and the other 6118P controlling the segments could be damaged as well, so be prepared for that.

===All Other Display Issues (Not Caused by Displays)===
There are several issues which appear to be display related, however, they ultimately are not. In these instances, the displays are used instead as a visual identifier of a particular issue.
 

====Open Slam Switch====
If after turning a System 80 game on, and the scoring displays turn on immediately without a 5 second delay, there is a problem. However, if the displays are showing all of the outer segments (all segments necessary to display a zero) lit, and "strobing" or "rolling" rapidly as simulated in the image below, this isn't a display problem. The cause of this problem is an open slam switch on the coin door. To address this issue, see the PinWiki section [[#Slam_Switch_Modification | Slam Switch Modification]].
[[File:Gtb 6digit slam scaled.gif|500px|thumb|left|Simulation of displays indicating an open slam switch. Note the "rolling" perimeter display segments.]] 

====All Displays Dim or at Half Brightness====
This applies to System 80/80A games with 6 or 7 digit displays. If all the displays appear dim or at about half brightness, check the 60v test point on the power supply. If it reads about 30-35v, then the dim display issue is caused by the power supply.

On the power supply, Q2 regulates the 60v, so if that component has failed, or if there is a problem with the solder joints or pads on the back of the board, this can result in half the voltage for the displays.

Carefully inspect the back of the power supply for cracked solder joints or through-hole pads that have popped off the PCB. Because Q2 has a large/heavy heat sink, the component tends to move around lot, which may cause these issues. If nothing is apparent with a visual inspection, test for continuity between Q2's legs and the traces on the PCB .

[[file:gottlieb-sys80-psu-q2-pad-problem.jpg|thumb|300px|left|The pad for the center leg of Q2 has separated from the PCB and will need to be repaired]] 

===Display Conversion for 6-Digit Games (Converting to 7-Digit Displays)===
[[Image:Gottlieb6DigitTo7DigitConversion.jpg|300px|thumb|left|Gottlieb® System 80 6-Digit to 7-Digit Signal Mapping. Click to expand. Image courtesy of Chris Hibler.]]
[[Image:GottliebAmazingSpiderman7DigitScoringExample.jpg|300px|thumb|right|Gottlieb® System 80 Amazing Spiderman with player 1 converted to 7-Digit scoring. Image courtesy of Chris Hibler.]] 
The signal mapping diagram shown at left details the wiring changes necessary to replace a 19 pin 6-digit display connector with a 21 pin 7 digit display connector. Note that some signals and power must be picked up from the 4-digit credit/ball in play display.

Once the wiring conversion has been completed, the appropriate game ROM that supports 7-digit scoring must be obtained and installed.
 

===Sound problems===
Before doing any kind of work, or blaming the sound board for not putting out sound, review the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting section] first.

[[Image:System80DIPSwitches.jpg ‎|300px|thumb|left|Gottlieb® System 80 Game Feature Selection DIP Switches and 1N4148 Switch Isolation Diodes. Image Courtesy of Chris Hibler.]]
In particular for System 80 games, ensure that the DIP switches that enable sound are set correctly. And, ensure that the dip switch actually works. Games like Spiderman use one of the 32 MPU dip switches to enable background and scoring sounds. Games like Haunted House, Black Hole, etc use dipswitch 5 on the Sound and Speech board to enable background sound.

Each DIP switch is isolated in the "DIP switch matrix" by a 1N4148 diode located directly below the switch. If one of these diodes fails open, then the switch closure will never be read by the MPU. If one of these diodes fails shorted, this may cause "phantom DIP switch closure(s)" in exactly the same way as a shorted playfield switch diode will cause phantom switch closures. Since System 80/80A diagnostics do not display DIP switch settings, this can be difficult to detect. Simple diode testing of each of the 32 1N4148 diodes is the best course of action.

Failed diodes in the "DIP switch matrix" can cause the switch(es) that enable sound features to be read incorrectly and therefore, sound behavior will be incorrect, such as lack of background sounds.

[[File:YT.png]] A video of one such failure that caused the background sounds in Black Hole to not work can be found [https://youtu.be/Q80TQ-W6XZ0 here.]
 

====The Long and Winding Road of the Sound Signals====
The sound signals follow very roundabout path before reaching their destination on the sound board. Sounds S1, S2, S4, and S8 are originated on the MPU board by RIOT U6. These 4 sound signals then pass through a 7404 inverter (Z27), pass through a 7408 2 input AND (Z31), and exit the MPU board via the A1J4 connection (MPU / driver board interconnect harness). The signals enter the driver board via A3J1, pass through another 7404 inverter (Z13), and exit the driver board via A3J5. Finally, they enter the sound board via the only connection on the sound board, A6J1.

If any of the sound signals are lost, this potentially happens due to poor edge connections, however, 7404s are known to fail too. The best way to check for discontinuity is to use a DMM or ohmmeter to check the path from the exiting chip to the chip it enters on the following board. Another method for checking for signal loss is a logic probe. This method is not as simple though, because some generations of System 80s do not have a sound test. Therefore, waiting for a particular signal to trigger can be tricky. The benefit of using a logic probe is to determine if a particular signal is entering and exiting a specific chip, and if the signal transforms (if it is supposed to) like intended (ie. the 7404 will invert the signal from high to low or low to high).

Some sound boards use a fifth sound signal, known as S16. S16 is actually driven by an MPS-A13 like any other single lamp drive. S16 can follow a very convoluted path too, depending on the particular game. For example, Haunted House uses S16. It originates on the MPU with all of the other lamp signals, and becomes lamp drive Q10 on the driver board. It exits the driver board via A3J2, passes through a inline connector, A10J4, passes through another inline connector, A12P4, and finally reaches the sound board at A6J1. That is a lot of mileage for just 1 little sound signal!

System 80B games, starting with Rock, which use the dual 6502 processor sound boards, use Q5 as sound signal S16. Please be aware that the System 80B documentation does not always notate this information regarding S16!!! In this case, S16 follows a much simpler path. It exits the driver board via A3J2 and goes directly to the sound board at A6J1.

So, if appears that certain sound signals are missing or the wrong sounds are triggered, suspect a bad connection first. Then, suspect a bad 7404 within the sound signal path. Then, check all other potential problems.

It is noteworthy that the 7404 U7 located on early System 80 sound boards (sound only) do fail also.

====System 80 Sounds Only Board====
[[Image:Gtb sys80 sound.JPG|300px|thumb|left|Gottlieb® System 80 Sound Board (Sounds only)]]
This board, first used in Panthera, is problematic to fix. The main issue is that the board uses the long since obsolete 6503 processor (think of it as a short 6502) and a "masked ROM/RIOT" 6530. The 6530 was specifically programmed for Gottlieb sound boards. They are therefore, impossible to replace unless you can scavenge a working one from another sound board.

The only replacement option at this time, other than sourcing a used board, is Pascal Janin's reproduction board. This board is a bit pricey but is engineered quite well. The board can be found here: [http://www.flippp.fr/pifx.php?lg=en http://www.flippp.fr/pifx.php?lg=en].
 

[[Image:GottliebSoundsOnlyBoardCorrosion.jpg|300px|thumb|left|A leaky audio filter cap caused significant corrosion to several traces on this board.]][[Image:System80SoundsOnlyLeakyCap.jpg|300px|thumb|right|Audio filter cap removed, corrosion removed, traces tinned. The leaky cap can be seen in the top of the picture.]] This board operates on three different voltages: +5v, +12v, and -12v. The +5 volts comes in on J1 pin 5 from the machine's power supply board. The +12 volts comes in on J1 pin 1 from the machine's bottom panel. The -12 volts is generated on the sounds only board and it receives AC power input on J1 pins 3 and 4. You can measure the -12 volts by connecting your volt meter across zener diode CR5 (1N4742A).

The test button on this era sound board will only work if the two dipswitches are set in opposite positions on the sound board.

As noted above, this board is tough to repair. If the 6530 is dead...you're SOL. A dead 6503 might be replaced. The other ICs on the board, like the LM380 amp and the 555 timer are still readily available.

A common issue with the board seems to be the leaky large capacitor on the board. Fortunately, this is easy to repair. Remove the old cap. Abate the corrosion as shown in the picture at right. Replace the cap. When this cap leaks, it can completely sever the sound signal path. Sounds might sound scratchy or incomplete too. The cap is easy to remove and replace. It's worth a shot.
 

====System 80 / 80A Sound and Speech Board====

=====Different Revisions of the Sound and Speech Boards=====
<center>
<gallery widths=300px heights=220px perrow=3 caption="Revisions of the Gottlieb Sound and Speech board">
File:SoundAndSpeechBoard-1Modified.jpg|<center>B20887-1</center>
File:GTB SS Back B20887-2.JPG|<center>B20887-2</center>
File:GTB SS B-20887-3 Back.JPG|<center>B20887-3</center>
</gallery>
</center>
 

[[File:GTB SS B-20887-3 Front Added Resistors.JPG|thumb|left|300px|B-20887-3 Sound and Speech Board with Resistors Highlighted]] 
With the third revision sound and speech board, the resistors which were added to the solder side of the -1 and -2 boards were now incorporated in the board design.
 

=====Sound and Speech Board Operation=====

The sound and speech board represents the high point in the System 80 family as far as sound generation is concerned. By combining sound and voice circuitry, the board is flexible enough to be used in several different games, with different voice calls, all generated via the Votrax SC-01 speech synthesizer.

The sound and speech board is itself a single board computer, and should be debugged similar to any non-working MPU.

The board interfaces with the System 80 MPU via a 6 bit (S1, S2, ..., S32) wide "data bus". The 6 interface bits form a binary code which define specific sounds (or speech) to play. This enables 63 separate sounds to be played. Each communication between the MPU and the Sound and Speech board is "stand alone". That is, the system does not make use of successive sound commands to mean different things as the Bally Squawk and Talk implementation does. In practice, since S32 is never used, a maximum of 31 unique sounds are commanded.

Four of the bits in the interface are controlled (grounded) by circuitry on the MPU (starting at the U6 RIOT) and a "pass through" 7404 inverter on the driver board (Z13). The remaining two bits are implemented via "lamp drive" transistors (Q10 for S16) on the driver board, and comparator circuitry on the S&S board (U24).

Sound select signals are fielded by the S&S board's 6532 RIOT which generates an interrupt to the 6502 processor. The 6502 reads the sound number commanded from the 6532 as it services the interrupt.

The S&S board's 6502's program code, as well as sound data, is stored in two 2716 EPROMs, PROM 1 and PROM 2. These EPROMs are typically labeled at the factory with the model number of the game they are for, and the suffixes /S1 & /S2. For example "668/S1" is the label on one of the Black Hole sound ROMs. Although the board can be strapped for two 2732 EPROMs, in practice, this was never done.

The sound and speech board can field and queue sound commands at the same time as it is driving the sound and speech circuitry lanes. The board will never interrupt or prematurely terminate a sound being played. The board will also never reorganize the queue of sounds to be played. Each sound to be played will be played until it's conclusion. The 6502 knows when "sounds" have completed playing since it is solely in control of the sound lane. The 6502 knows when "speech" calls have completed processing by the SC-01 via a non-maskable interrupt sent via the SC-01's ~A/R signal to the 6502's NMI pin. Timing to sequence speech phonemes together rapidly is critical, hence the use of the non-maskable interrupt.

The 6502 creates "sounds" via one circuitry lane. It creates "speech" through a second, separate circuitry lane. At the end of each lane, just prior to input to the main LM379S amplifier, sound and speech is summed. The relative volume of each lane can be tuned via 10K trim pots at the top of the board, R15 and R16.

Sound Lane 
Simple sounds (not voice) are created by the 6502 reading data from the sound ROMs and latching it into two 74LS75 data latches. The 74LS75s latch the data when selected via a 74LS02 (NOR gate) at U10 which NORs the R/W signal along with a device select signal from the 74LS138 at U4. the device select signal selects U7 and U8 simultaneously to latch data bus signals DB0 - DB7 all at once.

The two 74LS75s provide the data to a 1408 D-to-A (digital to analog) converter at U20. In this way, 511 different digital codes can be converted to analog levels by the 1408. The analog output of the 1408 can be attenuated via a 10K "variable resistor" at R13. The signal is then amplified and inverted by an LM741 analog inverter (U22). The analog signal is then fed to the LM379S for final amplification. Note that the 1408 DAC is obsolete, but may be replaced by the more available DAC0808.

Speech Lane 
Speech is ultimately created by the Votrax SC-01 voice chip. The SC-01 accepts "phoneme" codes and renders the analog speech output to the LM379S for final amplification. The phoneme codes are placed on the 6502 data bus and pass through a 74LS05 "level shifter" and inverter at U13. The codes are accepted by the SC-01 on pins 9 through 14 when pin 7 is strobed (the phoneme code is latched on the rising edge of the strobe). The "pitch" of the SC-01 voice is controlled by I1/I2 (pins 3 and 2). Frequency and timing control is achieved via MCK and MCR (pins 15 and 16, which are tied together). Frequency and timing are controlled via nearly identical circuitry as is used in the "sound" lane. Frequency and timing are referred to in the schematics as the "Voice Clock".

'''Reset signal''' 
The reset circuit is pretty simple. A 47uf/50V cap at C3 charges when power is applied. Once charged, the originating 5VDC power is twice inverted and cleaned up via a Schmitt Trigger at U1, and finally presented to the ~RESET signal (pin 40) of the 6502.

'''Test button''' 
The test button, located on the upper left side of the S&S board, grounds pin 17 of the 6532 RIOT. After reading the RIOT data, the 6502 process then plays the appropriate test sound, which varies by game.

'''SC-01 pinout'''

{| class="wikitable"
! Pin Number(s) 
! Signal Name 
! Signal Purpose 
|-
| 1 || <center>Vdd</center> ||  Input Voltage 
|-
| 2-3 || <center>I1, I2</center> ||  Instantaneous pitch adjustment. Will change pitch of phoneme being spoken. 
|-
| 7 || <center>S</center> ||  Strobe to indicate a phoneme code is ready 
|-
| 8 || <center>~A/R</center> ||  Acknowledge receipt of phoneme strobe, indicate completion of phoneme processing 
|-
| 9-14 || <center>P5-P0</center> ||  Phoneme number select (from fixed phoneme table) 
|-
| 15-16 || <center>MCK/MCR</center> ||  External Clock Signal (probably used to alter phoneme pronunciation via varying the clock) 
|-
| 20-22 || <center>CB, AF, AO</center> ||  Audio Output 
|-
| 18 || <center>Ground</center> ||  Ground 
|}

=====Sounds and Speech board DIP switch settings=====
The Sound and Speech board has a bank of DIP switches. For at least Black Hole, the function of these switches is as follows: 

*DIP-1 - Used in self-test only
*DIP-2 - Not used
*DIP-3/4 - Attract mode speech frequency
** OFF/OFF - disabled
** ON/OFF - attract mode speech every 10 seconds
** OFF/ON - attract mode speech every 2 minutes
** ON/ON - attract mode speech every 4 minutes
*DIP-5 - ON = background sound enabled, OFF = background sound disabled
*DIP-6 - ON = all speech enabled, OFF = all speech disabled
*DIP-7 - Not used
*DIP-8 - Not used

=====Sound "Locks Up" after certain switch closures=====
[[File:SC-01.jpg|thumb|300px|left|The long since obsolete, pricey, and hard to find SC-01 speech chip. This one is an SC-01-A, said to be a little beefier.]] 
This problem may be caused by a malfunctioning or missing SC-01 (or SC-01-A) speech chip.

Games such as Black Hole, Mars God of War, and Volcano utilized the SC-01 phoneme speech chip. These games require a working SC-01 to be present, not only for the speech portions of the sound, but for the sound to not "lock up" after the first time that a speech call is made. The CPU relies on an interrupt from the 6532 RIOT to restart sound command processing. That interrupt originates from an "all done" signal from the SC-01 speech chip (shown as ~A/R in the schematics, SC-01 pin 8). If the RIOT never receives an "all done" signal (at PB7) then it will not interrupt the processor and no further speech or sound will be created.

It is also possible that the 2N2222 at Q3 has failed, not allowing the interrupt signal to reach the RIOT. Q3 inverts the ~A/R signal and conveys it to the RIOT as A/~R and also to the MPU as a non-maskable interrupt (U3 6502, pin 6).
 

=====Game background sound continues after game over=====

This has been noticed in "Mars, God of War" predominately, but other System 80 games that use the Speech and Sound board may exhibit similar symptoms.

The cause of the problem is MPU DIP switch 25. The switch MUST be ON, as noted in the manual. Even if the switch appears to be "on", buzz across the switch solder pads on the back side of the board to ensure that the switch has not failed. Gottlieb sometimes used "rocker" switches, which seem to have a high failure rate. 

An "On Target" newsletter from June, 1981 discusses something similar to this problem.
 

=====Sound is "garbled" or phonemes appear jumbled=====


=====Using the MA-483 Sound Amp Board on a Sound and Speech Board=====
[[File:GTB 23172-1 Sound Amp Piggyback.JPG|300px|thumb|left|Gottlieb® MA-483 Piggyback Board]]
[[File:GTB SS Power Mod.JPG||300px|thumb|right|Gottlieb® Sound and Speech Power Supply with components highlighted]] 
If using the MA-483 sound amp board on a Sound and Speech board, or if the sounds only System 80A sound board is going to be used, the factory Sound and Speech power supply cannot be used without modification. The reason is because the original LM379S amp is powered by 30vdc, and the TDA2002 amp on the MA-483 can only withstand 16VDC. If a TDA2002 is powered by 30VDC, it would be destroyed. 

The modification is quite simple, and is done by replacing only two components (R1 and CR1). R1 is 430 ohm 1/2 watt and CR1 is 1N4751A 30v 1 watt zener diode. R1 should be replaced with a 1.5Kohm 1/2 watt resistor and CR1 should be replaced with 1N4746A 18V 1 watt zener diode.
 

=====Replacing the Obsolete LM379S Amplifier with a Modern Amplifier=====
''This information originally published by J. "kirb" Kirby. Additional pictures and some editing provided by Chris Hibler. Used with permission.''

Gottlieb System 80 Audio Amp Replacment...why?

[[Image:Gtb sys80&a s&s.JPG|300px|thumb|left|Gottlieb® System 80 Sound & Speech Board as used on Mars, God of War, Black Hole, Haunted House, Volcano, and some video games]] 
The Gottlieb® Sound and Speech board uses an LM379 or LM379s audio amp in the final amplification section. This amp became hard to find around 1983. Gottlieb® provided an alternative for this amp (see prior section) and discontinued using the Speech and Sound board further.

Their solution was to buy a piggyback board from Gottlieb® that used an LM2002 or a TDA2002 amp. But the LM2002 or TDA2002 amps require 16VDC to operate (instead of the 30VDC used by the LM379). This necessitated a change to the sound board power supply. There were many components to replace or remove, not to mention that you would have to make the piggyback board yourself.
 

SOLUTION? Find a newer amp that required fewer components. A replacment amp can be put together using only the following parts which can be easily sourced.

*LM1875T Audio Amp
*14 pin DIP socket
*Heat sink
*Heat sink compound

Once you've sourced these parts, a replacement amp is easy to construct and only requires removal of the old LM379 amp and addition of one jumper (to provide 12VDC, covered later).

Let's start with the basics. System 80 games used 4 different sound boards. This amp replacement applies only to the Sound and Speech board used in Mars: God of War, Black Hole (domestic version), Haunted House, Volcano, Devil's Dare, Caveman, Rocky, Q*bert's Quest, Super Orbit, Royal Flush Deluxe (early production), Amazon Hunt (early production), and video games like Q*bert.

LM379 Audio Amp Testing 

First of all, is your amp really bad? Basic tests to identify a failed amp...

*With the game on, turn the volume pot up as high as it will go. Do you hear a hum? This is normal and is an indicator that your amp is working.
*Check the voltages at the sound board. 30VDC is required to power the amp. Verify that this is working correctly or your amp won't work at all.
*Make sure the speakers are connected and working right. You can test speakers using a "D" size battery. Briefly connect the battery across the speaker and you should see the speaker's cone push out. Do this for only a second or two...speakers don't like DC voltages.
*Make sure the volume adjustment pot is connected correctly and working properly. A dirty pot will make sounds junky, but they usually don't completely fail. You can "twizzle" the pot to remove oxidation that may have formed on the internal conductors.
*Headphones can be used to see if the sounds are getting to the amp. Connect one of the headphone conductors (the one closest to the headphone "handle") to ground. Connect one of the other two headphone conductors (assuming stereo headphones) to the center leg of R15 or R16. You should be able to hear sounds that the board is making through the headphones. Your amp is probably bad if you can hear sounds at R15 or R16, but not through the speakers, assuming you've tested the speaker to be good and you have 30VDC power at the sound board.

LM379 Audio Amp Replacement Procedure 

Mark the "top" of the heat sink so you can later determine orientation of the original amp should this be necessary. Pin 1 of the amp can't be identifed without removing the two screws that secure the finned heat sink to the chips integrated heat sink.

Remove the LM379 amp and heat sink assembly from the board. Desolder all 14 pins and pull the amp off the board. The LM379 heat sink may be soldered to the board so you'll need to remove that solder too. Be forewarned, the solder pads are delicate and easily damaged. Note how the LM379 is upside-down in relation to other chips on the board. This will be important later.

Building the New Amp Assembly

Solder the new amp to the 14 pin DIP. Use the diagram below as a guide. The pinouts are as follows:

{| class="wikitable" style="margin: 1em auto 1em auto;"
! Amp Pin 
! Socket Pin 
! Purpose 
|-
|  pin 1 ||  pin 9 ||  + amp input
|-
|  pin 2 ||  pin 8 ||  - amp input
|-
|  pin 3 ||  pin 4 ||  Ground
|-
|  pin 4 ||  pin 10 ||  Audio out
|-
|  pin 5 ||  pin 1 ||  Vcc (+30VDC) 
|}

It will take some fancy bending to connect all of the amp legs in a way that they do not touch one another, but it can be done. It is important that the amp stands straight up and that the pins don't touch each other. See the diagram below for better info. Don't worry about the 12VDC connection right now. We'll connect that later.

[[File:LM379ReplacementNewAmpPinout.jpg‎|600px|center|Pinout schematic to attach the LM1875 amp to a 14 pin DIP socket]] 
<center>
<gallery widths=400px heights=400px perrow=2 caption="One Tech's Implementation (Heat Sink Added Later)">
File:LM379ReplacementAmpFrontSide.jpg|<center>Front side.</center>
File:LM379ReplacementAmpRearSide.jpg|<center>Rear side.</center>
</gallery>
</center>
 

Attaching the heat sink

First, yes, you need a heat sink. Audio amps run hot. Without a heat sink, the amps life will be dramatically shortened.

Mount the heat sink to the amp/socket assembly. You may have to modify your heat sink so that it doesn't contact anything but the LM1875 amp.

Heat sink compound should be spread on any metal to metal surface that is to conduct heat. This will improve the heat sink's efficiency and is a must on this device to work right. Without the compound, the amp will overheat and shutdown. It may even be damaged.

<center>
<gallery widths=270px heights=270px perrow=2 caption="Kirb's original completed assembly">
File:LM379ReplacementAmpSideViewKirb.jpg|<center>Side view.</center>
File:LM379ReplacementAmpFrontSideKirb.jpg|<center>Front view.</center>
</gallery>
</center>
 

The Final Steps 
[[File:CompleteAssemblyInSitu.jpg|300px|thumb|left|The completed assembly, mounted to the Sound and Speech Board.]] 
Solder the new amp assembly directly to the board. Normally you would use a socket, but that will lead to audio problems. It is better just to solder it into the board.

ACHTUNG! Remember that pin 1 of the amp solder pads on the board is upside-down relative to every other IC on the board, and you need to install your new amp assembly with pin 1 "down". Make sure this is done right. There is a 1 screened to the back of the board that should help you orient the assembly.
 

[[File:LM379Replacement12VDCSource.jpg|300px|thumb|left|Connecting 12VDC to the amp.]] 
Now that the pins are soldered to the board, we have to connect 12VDC to pin 14 of the socket. This is easily found at the positive (+) side of C39. This 12VDC biases the +IN so that it won't saturate. Your amp will only work for about 30 seconds without this 12VDC.
 

Check all of your work one more time, then test the amp and see what you get. If you've followed these steps correctly, your sound should be loud and clear!
 

===== Sound Mapping =====
The interface between the driver board/MPU and the sound board is a simple bit map. An example bit map can be found on the [http://www.pinwiki.com//wiki/index.php?title=Black_Hole Black Hole] specific page.

[[File:YT.png]] A YouTube video of each sound made by Haunted House can be found [https://youtu.be/_SAv4fS-G1w here].
 

====System 80A Sound Only Board====
=====Sound Cutting Out / No Sound=====
[[File:GTB 23172-1 Sound Amp Piggyback Back.JPG|300px|thumb|left|Piggyback Amplifier Board w/ Cracked Header Pins]] 
Gottlieb® had a tendency of using single-sided boards for their "piggy back" / daughter boards, and these boards are susceptible to cracked header pin solder joints. The MA-483 amplifier board is no different. If the sound appears to be cutting out or their are no sounds at all, the header joints on the MA-483 may have developed cracks. 

Before suspecting the daughter board header joints, review the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section located in the "General for all games" section.
 

====System 80A / 80B Sound with Piggyback Board====
The System 80A / 80B sound board is nearly the same as the first generation System 80 sound only sound board. It utilizes a 2716 EPROM versus a masked ROM like the System 80 sound board. This was potentially due to the Harris 7643 masked ROM being obsolete. The 80A / 80B board does not use a test button.

Like the System 80 sounds only board, this board has 2 obsolete chips on it, the CPU (6503) and the RRIOT (6530). On the plus side, these boards did not get destroyed nearly as much as the original System 80 sounds only boards (plugging the System 80 sounds only board into a System 1 game would destroy it in a very short time).

====System 80B Sound Board (MA-766)====
This sound board has two independent 6502 CPUs. One exclusively drives a DAC (digital-to-analog converter). The other drives the speech chip, Orator, (not used for speech on this generation of sound board, but it is used to generate sounds), and two AY-3-8913 sound chips. Each is pretty much independent, sharing essentially only the sound select lines, the reset signal, and the output section. The gates of one TTL chip are used by both 6502s to communicate between the subsystems via the NMI signal to each 6502 among other functions. The ROMs, CPUs, and accessory chips, are all localized to the particular subsystem other than the inter-processor communication just mentioned.

Note that the LED and test switch are only relevant for the CPU that operates the speech and synthesizer chips, not the chip connected directly to the DAC. With this in mind, it should be possible to troubleshoot this board using a divide-and-conquer approach. For instance, if the LED isn't blinking in/off at about a 50% duty cycle, then the subsystem for the 6502 that controls the LED has to have a fault, but the other subsystem may be fine.

Since this sound board is really just a more complex MPU board, or single board computer, the usual diagnostic steps are in order.
#Verify the ROM images are valid.
#Ensure that the reset signal begins low and then transitions to high after about 1/2 second.
#Ensure that the external clock signal is present at pin 37 of both 6502 processors.
#Ensure that the data lines on the 6502 (pins 33 through 26) are pulsing.
#Ensure that the address lines on the 6502 (pins 9 through 20, 22 through 25) are pulsing.
#Ensure that the external clocks are pulsing at pins 3 and 39 of the 6502 processors.

====System 80B Sound Board (MA-886)====
[[File:GottliebMA-886.jpg|300px|right|thumb|A repaired MA-886 sound board. Resistors R15, R16, R14, and R13 (top to bottom) are shown with blue Sharpie marks on their left ends, the end to probe when testing the sound channel. The other two components in the rectangle are high frequency ceramic filter capacitors which rarely fail.]] 
The MA-886 is generally the same board as the MA-766 sound board. The main differences are that the MA-886 uses .156" header pins instead of edge connections, the Orator chip was no longer used, and SW1 was abandoned.

Troubleshooting this board is nearly identical to the steps noted above for the MA-766 board.

One useful aspect of the board is that 4 channels of sound are summed by the LM324 at B1 before final amplification offboard.
*Channel 1 is the output from the 7528 DAC at E2. An example of the sounds that this channel makes is the "Destroy Alpha One" and other voices used in Robowar. This channel also contributes the "skittering" sound when the ball pass the rollunder on the ramp wireform and the "energy pulse" sound when the ball rolls over any of the top 4 lane rollovers. This signal passes through '''R16''' before summing.
*Channel 2 is the output from the AY-3-8913 (if present) at H4. This signal passes through '''R14''' before summing.
*Channel 3 is the output from the AY-3-8913 (if present) at K4. This signal passes through '''R13''' before summing.
*Channel 4 is the output from the MF-4 at E5. This signal passes through '''R15''' before summing.

Placing an oscilloscope probe on the end of these resistors attached to the sound generating circuitry for that channel should show a purposeful signal (versus noise). If not, it's a good bet that one of the devices in that sound channel has failed.

Several games (Bone Busters, Hoops, Bell Ringer, Silver Slugger, Car Hop, Deadly Weapon, Title Fight, and Vegas to name a few) use the MA-866 sound board paired with the MA-1294 auxiliary sound board. The two boards are connected via a special ribbon cable with dip "pins" on each end. WARNING: remove these connectors ONLY by sliding a flat blade screwdriver under it. Trying to "pull" the connector off with fingers on each side WILL cause the connector to be damaged. This sound board pair makes a two tone sound at power on. The two tones are different notes, like "LA-TI". The first tone originates from the YM2151 on the MA-1294 auxiliary sound board. The second tone originates from the 7528 DAC. If either tone is missing, or unclear, suspect the associated sound lane.
 

====System 80B Sound Board (MA-886) Jumpers J7 and J8====
[[File:GottliebMA886JumperComparison.jpg|300px|left|thumb|The left board is from Silver Slugger (a System 3 game) which has both J7 and J8 installed. The right board is from Night Moves which has only J7 installed.]]
[[File:GottliebMA886SchematicSnippet.jpg|300px|right|thumb|A snippet of the schematic for the two boards showing that without J8 installed, the sound board will not be "interrupted" to indicate a new sound command is to be processed.]] 
The MA-886 sound board was used in both System 80B and System 3 games. Two jumpers allow the board to be configured to accept the signal at connector P1, pin 9, as input. J8 IN enables this. J8 OUT defeats this. It's important to ensure these jumpers are installed appropriately for a particular game.
 

===Flipper Problems===
[[File:Sys80 Flippers.jpg|400px|left|thumb|Typical System 80 Flippers]] 
Gottlieb® System 80 flipper assemblies are very well engineered, and very little goes wrong with them. Due to this, they are considered to be the "Sherman Tanks" of flippers. 

Gottlieb® System 80/80A/80B games other than Bone Busters utilize the traditional "fat" flipper bat design (similar to Bally, Chicago Coin, and Stern), which is a carry over from the last flipper design of Gottlieb® System 1 games. The 3" plastic flipper bat is technically called a "flipper island" (Gottlieb® part number A-13150), and uses a 3/8" wide rubber ring versus the more common 1/2" wide rubber all other manufacturers use. Another anomaly regarding Gottlieb® flippers from this era is that they are the only flipper design that uses an upper and lower flipper bushing system. Neither bushing protrudes through the playfield.
 

System 80/80A/80B flippers (other than Bone Busters) use an A-17875 (standard), A-24161 (stronger), or A-20095 (strongest) dual wound flipper coil. The general design is a coil with two windings, the "power stroke" (low resistance) and "hold" (high resistance) windings, just like most other flipper coil designs. However, only a single diode is used with this serial winding design versus others which employ a dual diode, parallel winding design. Here's how it all works. When initially engaged via the flipper cabinet button switches, both the power stroke and hold windings receive power, however, the hold winding is bypassed or shorted by the end of stroke (EOS) switch (electricity follows the path of least resistance). As the flipper actuates and opens the EOS switch, the power is then transferred to both the power and hold windings (the resistance sum of the two windings), creating a very high resistance. The high resistance allows the coil to remain turned on without creating stress on the low resistance power winding. Hence, the coil can stay turned on indefinitely in theory.

Gottlieb® System 80/80A/80B flipper systems do not use a flipper relay per se. Flipper power flows through switch pairs on Q & T relays located under the playfield, along with other non-computer controlled coils like slingshots.

For problems and resolutions for the flippers used in Bone Busters, please see the [http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_3#Flipper_Problems Flipper Problems] section in the Gottlieb System 3 repair guide.
 

====Flippers Won't Work at All====
Like any flipper issue, it has be determined whether the problem is electrical or mechanical in nature. Start with obvious first. Look for broken wires at the flipper coil, EOS switch, and cabinet switch first. 

During visual inspection, make certain that the flipper EOS switch is closed (use an ohmmeter to determine this), and the switch pairs on the tilt and game over relays are properly gapped and closed. Equally, inspect the switch pairs to see if any of the switch blades are broken or missing their contacts. 

Since high current passes through all of the switches which enable the flipper, any of the switches may be suspect. It is somewhat common for games which have been sitting dormant for years that the cabinet switch and / or EOS switch become so fouled, the flipper will not budge at all. The remedy is to file these switches with an ignition file. See the [http://www.pinwiki.com/wiki/index.php?title=General#How_to_Properly_File_Switch_Contacts How to Properly File Switch Contacts] section. A flexstone will not work for this job, as the cabinet and EOS switch contacts are very hard. 

Inspect the cabinet switches for broken female spade connectors where the cabinet wiring attaches to the switch. 

Finally, look at the flipper plunger / link assembly. The plunger link is a hefty plastic piece which inserted into at hollowed out end of the flipper plunger. The link is connected to the plunger with a small roll pin. The link can break or the roll pin can fall out, due to vibration. If the link is no longer connected to the plunger, the flipper will not move at all. Refrain from trying to engage the flipper with the cabinet switches. Continuing to enable the flipper coil will stress the coil, because the EOS switch will not open, transferring power. The end result is an overheated flipper or damaged flipper coil.
 

====Flippers are Weak, Sluggish, or Erratic====
'''Wrong Flipper Coil Installed''' 
Gottlieb manuals of this era are a little confusing and misleading when documenting the flipper coils used in each game. The manual usually has a chart in the front half of the manual that lists all the coils that "could be" used in the game. This chart is the same for every game and lists multiple flipper coils (i.e., A-17875, A-24161, or A-20095), but not necessarily what is installed in that specific game or where it is used. To determine that, the schematics in the later half of the manual should be used to identify the coils that are supposed to be installed for each of the flippers in that specific game. It's somewhat common to see Gottlieb games with the wrong flipper coils installed; likely either because the operator didn't have the correct coils on-hand, or because the installer misinterpreted the information in the manual.
 

[[File:System1-80FlipperLinkDamageAnnotated.jpg|thumb|left|300px|A Gottlieb® System 80/80A/80B Flipper Plunger/Link/Crank Parts. Note the "hogged out" part of the link]] 

'''Worn Flipper Link''' 
The design of the flipper crank and flipper link / plunger is peculiar to Gottlieb® games. Gottlieb® games from the System 80/80A/80B era use a very meaty flipper link, which does not have a pivot point between it and the connected plunger. To achieve the necessary fulcrum, the flipper link has an oval opening at the point where the link and flipper crank connect. The two pieces are simply connected with a roll pin protruding through the two parts. Over time, the roll pin can sometimes cut into the opening in the link, and the roll pin will catch as the flipper crank pivots. The result is a weak flipper or a flipper which does not return to the at rest position. Using a roll pin punch tool, remove the roll pin, and replace the flipper link / plunger assembly. Pay close attention when installing the roll pin into the new plunger link. It is very easy to cut into the link with the roll pin, deeming the new link / plunger worthless.
 

'''Flipper Crank Installed Incorrectly''' 
Reassembling a flipper bat / shoe incorrectly can result in a weak flipper. Before tightening the two set screws which hold the flipper shaft in place, make certain that the flipper crank is centered equidistant between the upper and lower flipper bushings. If placed too close to the upper bushing, it will "sandwich" the upper bushing between the crank and bat. If placed too close to the lower bushing, the crank will have friction between it and the lower bushing. The end result is a weak flipper or a flipper which does not return to the at rest position. 

'''Fouled / Pitted Switch Contacts''' 
Fouled switch contacts can reduce current, which in turn reduces power / strength. Make certain that the EOS switch, cabinet switch, and switch pairs on the game over (Q) and tilt (T) relays are all clean and not pitted. Filing the contacts with an ignition file will remedy the problem, provided that the contacts are not heavily pitted. 

'''Bad Connection to Cabinet Switch''' 
Another problem related to the cabinet switches is the female spade connector used to connect the cabinet wiring to the switch. These spade connectors can sometimes become sloppy or break. In most cases, the break is not evident, until the connector is removed and reinstalled on the cabinet switch tab. The spade connector can be removed and a new one crimped on, or the better solution is to solder the cabinet switch wires to the tabs on the cabinet switch. 

'''Worn Flipper Plunger''' 
A mushroomed flipper plunger can create excessive drag within the coil sleeve. When replacing the plunger / link, replace the coil sleeve and coil stop too. 

'''Broken Coil Stop''' 
The coil stop "slug" is pressed into the coil stop bracket. It is somewhat common for the slug to become detached from the coil stop bracket. The coil stop slug will then be "free floating" within the coil sleeve. This can create some interesting problems, but the most noticeable are reduction in flipper power, decrease in flipper stroke or both. 

'''Incorrect Flipper Rubber Installed''' 
Gottlieb® used 3/8" wide rubber on flippers. It fits perfectly into the groove on the plastic flipper bat. Everybody else used 1/2" wide rubber, and that tended to get installed on the Gottlieb® games, too. When a 1/2" wide ring is used, it almost fits, but because of the groove, it will present a funny angle to the ball instead of a flat plane. The results are either air balls, or the flipper will smack the ball downward into the playfield. 

'''Cracked / Broken Plastic Bat''' 
Sometimes the flipper bat cracks. Replacements are available. The screw that holds the plastic flipper bat on the metal shoe is located on the underside of the flipper. Loosen the two set screws on the flipper crank, and the shoe and bat will come free.
 

'''Broken Hold Winding''' 
Erratic flipper function is defined as a flipper which will not remain in the up (hold) position when activated. The flipper will move rapidly up and down as if it is "machine gunning". This is typically the result from a break in the hold winding right at the flipper coil lug. One resolution is to locate the broken coil winding (this will be the thinner of the two windings), and unwind one turn from the coil. This can be accomplished if the side of the winding is not connected to the common lug of the flipper coil. Note that the power winding cannot be unwound if it breaks. This is because the power winding is wound on the coil bobbin first, and is located beneath the hold winding. Once one turn of the hold winding is unwound from the coil, the excess length must be shortened. After the correct length is determined, the portion of the winding which will be soldered to the coil lug must have its insulation stripped off. The red or green hue on the coil winding is actually a thin insulation, which is used to keep the winding from shorting to adjacent windings. Gently scrape the coating off the winding by using an exacto or utility knife, exposing the copper wire of the winding. Then wrap the uninsulated winding around the coil lug, and solder it. If a single winding cannot be removed from the existing coil, complete coil replacement is the solution.
 

====Flippers Will not Return to at Rest Position====
The EOS switch assembly is actuated by the pointed part of the flipper crank assembly. This is a metal-on-metal contact point. Due to the design of the flipper crank, it will eventually wear a hole in the EOS actuating blade. The fix is to replace the EOS switch assembly. About halfway through the System 80B games (around TX-Sector or so), the EOS switch was slightly relocated, and a modified flipper crank actuates the switch with a roller. An MA-988 or MA-989 kit can be purchased to perform this upgrade on any System 80/80A/80B game. 

As mentioned in the previous section, the flipper link can become cut by the roll pin which secures it to the flipper crank. This can also cause the flipper to not return to the rest position. 

Also mentioned in the previous section, the flipper coil stop slug can detach from the coil stop bracket, causing the flipper not to return completely. 

If the flipper return spring has become stretched or is no longer connected to the flipper crank or coil stop anymore, the flipper will not return properly.
 

===Pop bumper problems===
[[File:Gtb pbdb new.JPG|thumb|300px|left|Corrected/Modified Gottlieb® System 80/80A/80B Pop Bumper Driver Board]]
The pop bumpers on all System 80 / 80A / 80B games are controlled by an under playfield mounted board known as the pop bumper driver board (PBDB). Remote pop bumper driver boards are unique to Gottlieb® System 80 games. No other manufacturer made this design decision. The reason Gottlieb® did this is probably to supplement the number of coil drive circuits as well as to solve the common problem of pop bumpers locking on with subsequent damage to the games components. 

Each pop bumper has its own board. Each board provides a consistent, strong pop regardless of how long the spoon switch is activated, and ensures (when working properly) only a single pop per actuation of the spoon switch. 

These boards are single-sided construction, where the traces are located only the solder side of the board. Due to this construction, the solder connections crack easily. Reflowing the solder of the header pins on any suspect boards is recommended to ensure a good mechanical and electrical connection. The components should be inspected as well, because they can also have cracked solder connections that will need to be touched up. 

If the pop bumper fires but does not score, examine the secondary switch on each pop bumper to see if it needs cleaning or adjustment. This switch is part of the switch matrix, and can be tested by manually pulling the pop bumper rod and ring down to activate it.

====Pop Bumper Driver Board Power and Ground Source====
[[image:PBDBPowerGroundConnection.jpg]] 
As can be seen in the schematic snippet above, Pop Bumper Driver Boards receive 5V power and a connection to ground via MPU connector A1J6, pins 18 and 9 respectively. A poor connection at these pins will render the pop bumper driver board, and hence the associated pop bumper, inoperative.

Testing to see if the PBDB is receiving 5VDC and ground can be accomplished by measuring between pin 7 (ground) and pin 14 (5VDC) on either of the integrated circuits on the board.

Lack of 5VDC power (or ground) may also be caused by fractured solder joints on the PBDB header.

Note: Pin 2 of each pop bumper driver board connector is the path to ground for solenoid power. This ground is connected to the transformer chassis via one of the many equally dicey methods Gottlieb used. See: [[Gottlieb_System_80#Recommended_Ground_Improvements_for_System_80B|Recommended Ground Improvements for System 80B Games]].
 

====Updating the Pop Bumper Driver Board====
Gottlieb® issued a service bulletin to correct a design error with the PBDB. A great many of these boards were delivered in games prior to correcting the design at the factory. Examine the PBDBs to ensure that they have been updated. See the pictures below, noting the differences. '''A dead giveaway would be the lack of a jumper to replace CR1.'''

<center>
<gallery widths=300px heights=150px perrow=2 caption="System 80/80A/80B PBDB Before/After Modification">
File:Gottlieb-UnModifiedPBDB.jpg|<center>Unmodifed PBDB</center>
File:Gottlieb-ModifiedPBDB.jpg|<center>Modifed PBDB</center>
</gallery>
</center> 

[[File:Gottlieb-ModifiedPBDBPartsExplanation.jpg|thumb|300px|right|Gottlieb® System 80/80A/80B PBDB Update]]
Should your PBDB require update, follow this procedure:

*Acquire the following parts 
**Cut to length .156 Molex male header pins with locking ramp (you'll need a 6 pin length) 
**47uf/10V electrolytic capacitor (C4) 
**4.7uf/10V capacitor (C3, tantalum or electrolytic, may be axial or radial) 
**Jumper material (use the remaining leg cut from C4 when you install it) 
*Remove CR1, C3, and C4 
*Replace the Molex connector or reflow the solder on each header pin 
*Install C4 (47uf/10V) with the negative side facing the male header pins 
*Use the remaining part of the capacitor leg from C4 as a jumper to replace CR1. Any jumper wire will work...the cap leg is convenient, available, and looks professional when installed nice and straight. 
*Install C3 (4.7uf/10V), reversing the original polarity so that the positive side faces the jumper just installed and the negative side faces the nearest board edge. Note that C3 may be axial (leads from both ends along the components "axis") or radial (leads on one end of the component). The board is designed to accept either style. 
*Ensure that the large can transistor (2N6057, 2N6059, PMD10K40 or PMD10K60) solder joints are solid and that the bolted end is making good contact with the PCB trace. 
*Test the large can transistor... 
**DMM set to "diode test" 
**Black lead on the nut that secures the transistor 
**Red lead on each leg of the transistor 
**A measurement between .5 and .7 should be seen. Readings significantly outside of these ranges indicate a failed transistor which should be replaced. 
*Examine the remaining solder joints on the board to ensure good solid joints and no lifted traces. Note that the trace between the jumper that replaces CR1 and R2 is particularly susceptible to damage and if broken, will cause the associated pop bumper to lock on.
*Reinstall the PBDB and test. 

There is an update for the PBDB that gives the board a bit more "pop". Simply replace R1 (1.5Kohms) with a 10Kohm 1/4W resistor and replace C1 (0.01mfd) with a 1 mfd 100 volt (non polarized) capacitor.

Also, to avoid random, uncommanded pops caused by "noise" on the switch line, you can add an electrolytic capacitor to the solder side of the board. Use a 4.7 mfd 16 volt radial capacitor (both leads on one end). Solder the negative lead of the capacitor to pin 4. Solder the positive lead of the capacitor to pin 5.

=====Replacing the 2N6057 with a TIP-102=====

[[File:popdrivertip102.jpg|300px|thumb|left|A TIP-102 installed on a Pop Bumper Driver Board (PBDB)]]
[[File:PBDTIP102.JPG|300px|thumb|right|Closer view of a TIP-102 installed on a PBDB]] 
The 2N6057 used on Gottlieb games is obsolete, so it is hard-to-find and expensive. A cheap and effective substitute for the 2N6057 as used on the PBDB is a TIP102 transistor. It's not the most elegant "hack", but it works well.
 

===Drop Target Problems===

====Early System 80 / 80A Drop Target Removal====
For now, please review the drop target removal guide available at [http://www.papinball.com/tips/gottlieb_drop_target_guide2.html PAPinball.com].
 

====Later System 80B Drop Target Removal====
This is a stub 

===Vari-Target Problems===
The single largest problem with vari-targets is adjusting the spring tension, which returns the vari-target to the at rest position. The spring can be adjusted by hooking it to one of two screws which hold the spring in place. In most cases, there is only one screw, but two screw holes are placed 180 degreees from one another within the vari-target frame. Spring adjustment should be made so that the vari-target barely returns to the home position, when the playfield is upright (resting against the backbox). Once the playfield is placed in its proper position, gravity will help with the extra "bump" that the vari-target needs to return home. 

Also, the switch leaves of the vari-target, which "ride" along the rivet board need enough tension to make good solid contact with the rivets. Since it's impossible to bend the switch leaves closer to the rivet board with the rivet board in place, removal of the vari-target rivet board must be done to make this adjustment. 

Vari-targets seldom require adjustment as they were correctly adjusted at the factory. It is possible to move parts of the mechanism so that the switch no longer comes to rest on a rivet when the vari-target "gear" is stopped by the reset relay armature.

Vari-targets are a rare example of where lubrication helps the operation of the mechanism. A thin film of lithium grease on the rivets helps the switch blade "wipe" cleanly across them. Like [http://en.wikipedia.org/wiki/Brylcreem Brylcreem], "a little dab'll do ya". Note: That's humor son...Brylcreem is not a suitable lubricant...for pinball machines. :-)
 

===Roto Target Problems===
By the time System 80 games first came out, the roto target was a dying assembly. The believed reason is due to the amount of playfield "real estate" in which it used underneath a playfield. Circus is the only System 80 game which used the roto target.
 

==Parts Substitutions & Replacements==
===Cabinet===
* Power cable strain relief bushing, 80A games: Heyco 7k-2

==Game Specific Problems and Fixes==

Black Hole issues have been moved to the dedicated [http://www.pinwiki.com/wiki/index.php?title=Black_Hole Black Hole] page.

===Alien Star Game Start Failure===
Alien Star has a major fault when running the original 689 code. For the game to properly start, one ball must be in the trough and one ball in the outhole. If both balls are located in the trough, only the single trough switch will be closed, and not the outhole switch. When only the trough switch is closed, the game *thinks* that only one ball is installed, (2 balls total are needed), and will do absolutely nothing. 

It has not been verified, but running 689A code may resolve this issue.
 

===Haunted House - Upkicker Plastic Tube Mounting Bracket===

[[File:Cornell_VR4_cap_bracket.jpg|300px|thumb|left|Mounting bracket for the plastic tube.]] 
The metal mounting bracket that secures the longer plastic upkicker tube to the main playfield breaks its tabs (ears) off allowing the tube to flop around loose. This bracket is actually an electrolytic capacitor mounting bracket for computer grade capacitors. If broken, Mouser Electronics sells this item as part number [http://www.mouser.com/ProductDetail/Cornell-Dubilier/VR4/?qs=0r35cIPu56HWvTGFwxXK2g%3d%3d 539-VR4]. The OEM part is a VR4, which is manufactured by Cornell-Dublier (Mallory).
 

===Spring Break - Shooter Lane Switch Required to work or ball will drain and game will "brick"===

[[File:SpringBreakBallLaunchGateCropped.jpg ‎|300px|thumb|left|Ball gate at exit to Spring Break shooter lane. The spring actuates a switch below the playfield. Image courtesy of Russell McIntyre]] 

Spring Break is configured to start a multiball at the start of every ball. The game uses a "shooter lane exit" switch or any scoring switch, to know that a ball has been put into play, enabling subsequent balls to launch. If this switch is malfunctioning, and a ball is launched that scores no points before draining, the game will be "bricked" requiring a power cycle. The key is scoring points and the shooter lane exit switch scores 300 points. This seems like a "hack" created by Gottlieb once this "feature" was discovered. 

===Devil's Dare - All Displays out except status display===
[[File:DD Resistor Before.jpg|thumb|left|300px|Burnt 200 Ohm resistor on +60VDC display power line]]
[[File:DD Resistor After.jpg|thumb|right|300px|Replacement 200 Ohm 2 watt resistor on +60VDC display power line]] 
If the game in question is a Devil's Dare, and all of the displays are out except for the status display, and the +60VDC is present at the power supply, but not at the displays, the following may apply. Some Devil's Dare games, (it is unknown exactly which ones at this point), have a 200 ohm resistor installed in series with the +60VDC power line for the displays. The resistor is located on the lamp insert board, just behind the lower right 6 digit display. The resistor is soldered to two solder eyelets, so replacement is relatively easy. It is unknown what the purpose of this resistor is, but it is fairly common for the resistor to overheat and potentially fail. The recommended replacement for this is a 200 ohm 2 watt resistor. 

There is no information regarding the value or placement of this resistor in the Devil's Dare manual / schematics.
 

===Mars God of War (MGOW), Volcano - Background Sound Continues After Game is Over===
If the background sound continues after the game is over, this may solve the issue. Even though the manual states that dipswitch 25 on the CPU board is not used, try placing switch 25 in the "on" position.
 

=== Volcano Kick Back Ends Prematurely ===
[[File:VolcanoKickBack.jpg|300px|thumb|left|The Volcano kickback mechanism.]] 
The kickback mechanism in Volcano, once enabled by a playfield feature, remains available until the player uses the feature by pressing the green cabinet button in front of the flipper switch. The game knows that the feature has been used by sensing the switch at the rear of the mechanism. As the plunger pulls in, the normally closed switch is opened by the ring on the rear of the plunger. If this normally closed switch isn't "making" solidly, the game will think that the plunger has pulled in. The kickback feature will be considered used and hence disabled.

The behavior looks like the feature has timed out prematurely.
 

=== Games with Playfield Windows: Black Hole, Haunted House, Genesis, Monte Carlo, etc. ===
Playfield windows use foam washers that provide "counter force" to help keep the window flush with the playfield. If the window isn't flush with the playfield, the "lip" of the sunken window in its mount will cause airballs and/or the edge of the playfield will wear excessively.

After a couple decades, springy foam washers turn into hard, crumbly foam washers. Weatherstripping ("beer seal"), cut really small, works in a pinch, but the Pinball Resource stocks the proper foam washers (GTB # 21219). Strips of tool box drawer liner work as well, but there is only one chance to crank them down before they compress.
 

==Repair Logs==
Did you do a repair? Log it here as a possible solution for others.
==== Game Displays 000000 On Power Up and It's Not The Slam Switch ====
If you power the game on and all of the displays immediately display all zeros without strobing the problem is usually with the slam switch. However, if the slam switch modification has been done or the slam switch is working properly there is a problem with the switch matrix.

I had this problem on my Haunted House machine. I finally found that chip Z15 (7432) was bad.

I was fixing a kicker solenoid on the playfield, the playfield was still in the machine and fully in the upright position. While I was soldering the wire to the new solenoid I did not adequately protect the components below from a solder drip. Well, I did have a solder drip that landed right on a pop bumper driver board connector and shorted the connector. The short caused more than just this problem but for this narrative we will restrict to the slam/switch matrix problem.

Reading in other materials I recognized the problem as the slam switch issue. I used a logic probe to test other components and found the CPU board working, mostly as it should except for acting like the machine was slam tilted. There was little written about the problem outside of the slam switch. I decided to check the matrix by doing a diode check on all of the diodes in the switch matrix. When I did this, I found that many of the diodes were testing bad. These were being tested with the board removed from the machine.

Having replacement diodes in my parts drawer I decided that these must have gone bad during the short. I began unsoldering a few of the diodes. Once disconnected from the circuit board I remeasured the removed diodes and found the correct values on my meter, they were not bad. I then noticed that the bad diodes were all in the same row on the switch matrix. They all traced back to the Z15 chip. I replaced the Z15 7432 and the problem was resolved.

====Game Displays a single 0 or 1 on Displays====
If an 80A game does not boot and displays just a single zero, just a single 1, or alternates between a single zero and single 1, this may indicate one or more bad IC(s) on the MPU:
* CPU
* Z7
* Z8

The CPU itself may still output data that can be picked up with a logic probe, but still might be bad.

[[File:Gottlieb-sys80a-bad-cpu-display-symptom.gif|thumb|300px|left|Animation of symptom of alternating 0 and 1]]
[[File:Gottlieb-sys80a-bad-cpu-display-symptom-zeros.jpg|thumb|300px|left|Symptom of the displays showing a single zero]]

 

==== Testing the Q relay ====
Had a problem with my Black Hole - Q relay didn't activate. Played a bit with wires, did ground mods, ..
After a while I noticed it did work but didn't stay enabled - at the start of a game it closed, 1 coil (ball drain) kicked and the Q relay deactivated again. Noticed this with the playfield in up position, no pinballs installed.
Finally tested with playfield down - and pinballs installed - suddenly the behaviour was different: ball drain coil kicked and then the next coil also that put a coil in the shooter lane. Seems the Q relay did work all this time, but will only stay enabled when pinballs are installed in the game ?!

==== Results of a locked on coil ====
[[File:BurntCoil1.jpg|300px|thumb|left|Melted coil sleeve.]]
[[File:BurntCoil2.jpg|300px|thumb|right|Burned coil wrapper.]] 
If a coil locks on (due for example to a bad driver board transistor), the coil will burn. Here is a coil which had locked on. Note the burn marks on the paper wrapping and the melted coil sleeve, which prevented the coil plunger from moving through the coil. The resistance of this coil was 0.9 ohms (the specified resistance for this particular coil should be 3.35 ohms), also indicating it's bad due to an internal short (adjacent windings shorted together due to overheating the coil wire insulation).
 

==== Black Hole top rollover switches ====
When Black Hole serves a ball, it must go through the top rollovers before hitting any other switch. The playfield design ensures this. But if it doesn't (I had the glass off and started testing some other feature), things get very weird: suddenly, I seemed to be in a 3-ball, 4-player game with some of the score displays blank.

This isn't usually a problem in practice but it is worth making sure that the three top rollovers have clean switches.

==== Replacing the 80B 5V pot ====
I got a Monte Carlo and replaced the 5V adjustment pot on the regulator. It was working fine. After the old one had been chopped off, I discovered it was the same as the new one. It had already been replaced! A bunch of rework on the regulator, and ground mods on the transformer frame, should have been my clue.

==== 80B sound doesn't work ====
I got a Spring Break and the sound didn't work. The LED didn't light in any predictable way, and the game put out a lot of white noise. At one point I thought I heard some sounds underneath.

Fortunately, I had a Monte Carlo sitting next to it where the sound did work. I spent some time trying to understand the problem, and finally just swapped all the socketed chips (three EPROMs and the "Orator" speech synthesizer). The problem followed the EPROMs, not the board. Ultimately I replaced all three ROMs, although it seems likely that only one was likely bad.

Note that the sound board has two separate CPUs, and only one controls the LED, so it is likely one of the two EPROMs associated with that CPU that is actually bad.

==== Two flash lamp problems ====
Monte Carlo has four pairs of flashers controlled by "lamp" drive transistors, stepped up by under-playfield transistors. On my game, I had two unrelated problems with different flash banks.

The two sockets by the roulette wheel were missing their lamps, and the under playfield was a little burned near where the lamps had been. Apparently they were locked on, and someone had pulled the bulbs rather than fix the problem. I replaced Q17, which was out of spec according to the measurements on this page. I didn't replace the under-playfield MJ2955 because it seemed to measure correctly. One down, one to go.

The other flasher, the two on the left side, just didn't work. Lamp bulbs were fine, and all transistors seemed OK by the tests given above. I checked for continuity in the wiring and even tried grounding the transistor side of the circuit, but no lamps lit. Finally, I pulled the plastic off to take the bulb out (to measure at the socket) and I found that the two lugs of the socket were bent and touching! So the lamp was a short, but because of the resistor, not short enough to blow the fuse or fry the transistor. A little bending back seems to have fixed it. -- [[User:Ts4z|ts4z]] ([[User talk:Ts4z|talk]]) 16:29, 7 February 2014 (CST)

==== 80B Display has garbage on one display glass ====
Chicago Cubs had garbage/nonsensical characters on just the lower score display. I found chip U2 (type 10939) which controls the lower display to be bad. Replacing the chip cured the problem. I also installed a 40 pin IC socket for the replacement chip. If by chance you encounter the same symptom except that it is on the upper display, then chip U1 (type 10939) is bad. U1 controls the upper score display.

====Rebuilt 80/80A Power supply, solenoid fuse blows on power up====
If a System 80/80A power supply has been rebuilt and the solenoid fuse blows as soon as the game is turned on, take a look at the power supply capacitor at C1. It might have been installed in the wrong direction. Make sure the (-)side on the capacitor matches the (-) side notated on the PCB.

==== Haunted House ten thousand digit out on several displays ====
Encountered the ten thousand digits missing on three displays: player 1, player 3, and bonus display. Tried several known good cpu boards and problem remained. Tried swapping displays and problem remained. I traced the problem to the wiring harness on the main playfield. At the playfield mounted transistor Q2, the transistor mounting bracket had cut into the wiring harness. I repaired the harness with electrical tape and routed the harness farther away from that bracket with a couple of wire ties. Problem fixed and all displays are now working correctly.

General

2022-08-28T13:45:40Z

Jimpal: /* Exceptions */

=Introduction=

This section of PinWiki hosts general information common to all/most pinball machines.

=Safety=
==Grounded 3-Prong Plug==
[[File:3Prong Clipped.JPG|200px|left|thumb|Typical "clipped" 3rd prong on plug]] 
If the earth ground prong of a 3-prong plug is clipped or missing, replace the plug. Many of these plugs were clipped, because some older locations where games were placed only had two-prong outlets. The 3rd prong connects the games electrical circuits to "earth ground". In place, it reduces the risk of shock and protects the user. If you have neighboring machines and you feel a "tingle" when you touch the metal rails on both, one or both machines have a missing ground prong.

Use a multimeter set on continuity to ensure that the ground pin is connected to all the metal touchable parts of the game - the rails, the coin door, the legs bolts, etc. Investigate any missing wires and correct. Older games that came without a ground plug should have one added. Attach the green ground wire to the metal frame of the game transformer. Connect ground wires to all touchable metal parts on the game.
 

== Replacing a Grounded 3-Prong Plug ==
[[Image:GroundedPlug.jpg|200px|thumb|left|A typical replacement 3-prong plug available from many "big box" stores.]] 
Most 3-prong plugs will have a green colored screw attach point used to attach the green ground wire. 
The right prong (looking at the plug from the front, oriented like a "smiley face"), is the wider, polarizing plug. It may have a silver screw, or a screw attach point colored silver. In the US, the white wire (neutral) attaches to this prong. In Europe, the UK, Australia, and Canada, this wire might be colored blue.

In the US, the remaining (left) prong attaches to the black wire (hot). In Europe, the UK, Australia, and Canada, this wire might be colored brown. The hot screw will typically be gold in color

The memory mnemonic to remember this is "White to Bright". Also, if you think of oil as "Black Gold" - Black to gold.
 

[[Image:RibbedCord.jpg|200px|thumb|left|A close up of a "ribbed" power cord.]] 
When installing a new 3-prong plug on a 3-conductor lamp cord (flat wire without colored wires, except green for ground), the neutral wire is typically the conductor with "ribbing" molded into the sheathing. When in doubt, perform a continuity test between the stripped wire end, and where it connects within the game.
 

==Overfusing==
[[File:BoltForAFuse.jpg|200px|left|thumb|The never blow, 1.21 GigaWatt fuse. Obviously, this is NOT recommended.]] 
Fuses are designed into your game's electrical circuitry to protect the circuits from damage should some component fail and begin to draw too much electrical current. They are designed to be the "weakest link" in the circuit. When too much current is drawn through the circuit, the fuse should be the first part of the circuit to fail.

Although fuses sometimes fail due to old age or vibration, fuses usually fail for a reason. Locked on coils or flashers, direct shorts of power to ground, and many other reasons will cause a fuse to blow. If you replace a fuse, and it blows again, then you can be sure that something has gone awry.

Always install fuses at the rating specified for your game. Installing a fuse rated higher than spec may cause some other part of the game circuitry to become the weakest link, and damage parts of the game that the fuse is designed to protect.

Fuses are rated in terms of voltage and most importantly amps. Fuses are also designed as "fast blow" or "slow blow"/"time delayed blow". Typical sizes for pinball machines are 1.25 inches and 20mm.
 

=Parts to have on hand=
'''All Machines'''
*[[General#Lamp_Chart| Bulbs/Lamps]] #44/47, #555, and #89 are very common types.

'''Electromechanical Machines'''
*455 "Blinker" type bulbs for backglass highlights. Helps with heat in the head as well as they are usually about 50% duty cycle.
*Replacement switch blades and high voltage contacts

'''Solid State Machines'''

*Replacement micro-switches. A long lever micro-switch is a generic replacement that you can cut/form to the shape you need.
*Replacement leaf blades and gold flashed contacts
*TIP-102 Transistors
*IN4004 Diodes
*.156 and .100 Molex header pins (the "break to size" style is the most versatile)

=Tools of the Trade=

You'll probably build your toolset as you go, but the following list is a general set that can accomplish many pinball repairs.

==Mechanical Tools==
*Hex Key set/Allen Wrenches. 5/32" (4mm) is used on flippers. 5/16" is used for Stern (DE/Sega) head latches if the game's tool can't be found.
*Needle nose pliers - a mini-pliers set is handy
*Nut driver set, which should include
**1/4" nut driver - the most common size, used for hex head screws and hex posts
**5/16 nut driver - used for #6 nuts
**11/32 nut driver - #8 nuts
**3/8 nut driver - used for #10 nuts
**OPTIONAL: 1/8" nut driver - used for microswitch nuts in some Sega ball troughs
**OPTIONAL: low torque or torque controlled electric screwdriver and 1/4" bit. Really makes quick work of standard screws. Don't over-tighten.
**Great OPTION: Magnetic tipped nut drivers, especially for driving the hundreds of 1/4" screws into Williams playfields.
**OPTIONAL: Stubby nut drivers, particularly 1/4". They can be useful for getting to playfield locations that are under the head.
**OPTIONAL: Long nut drivers for 1/4" through 3/8". The 8" ones work well for reaching through playfield harnesses.
**OPTIONAL: 24" 1/4" nut driver. If the almighty repaired pinballs, he'd use one of these. [http://www.amazon.com/Klein-Tools-618-1-4M-Magnetic/dp/B000TKF8A8/ref=sr_1_1?ie=UTF8&qid=1438146129&sr=8-1 18-inch version]
*Screwdriver set. Should include #1 and #2 Flat head and Phillips head at minimum.
*Security Torx Bit set. Used on newer machines for lock plates and topper domes.
*Socket wrench with 9/16 and 5/8 at minimum. Used for leg bolts and head bolts.
**OPTIONAL: Socket spinner handle. Can sub for a nut driver you don't have.
**OPTIONAL: 1/4" deep socket. Some of these are deep enough to envelop certain pots with hexagonal bases.
*Wrenches
**3/8 wrench - used for tightening flipper pawls. UPGRADE: gear wrench...excellent for WPC flipper nuts
**9/16 wrench - used for head bolts, some leg bolts, and some leg levelers.
**5/8 wrench - used for leg bolts and all the other leg levelers. UPGRADE: gear wrench
**OPTIONAL: One 4" adjustable end wrench. With a set of standard wrenches, this is just a backup. Or it can save a lot of weight in the toolbox.
*Pliers
*High-brightness LED flashlight
*Magnetic pickup tool
*Magnetic parts dish
*Hemostats (clamps that look a bit like scissors, for soldering)
*Torpedo level - used for leveling game from side to side
*OPTIONAL: E-clip tool. MCM Electronics 22-2790, Jonard CS-1022. For removing and reinstalling e-clips. Greatly reduces the number of e-clips that go AWOL.
*OPTIONAL: Offset screwdriver with 5/32 or 4mm bit. These are fantastic for working on Stern flippers, and great when working on older Williams cranks.
** [http://www.amazon.com/General-Tools-Instruments-8071-Pass-through/dp/B00004T7TZ?tag=ahb35js-20 General's offset screwdriver 8071] is great as it has a forward/reverse switch, but comes with the wrong bits.
** [http://chapmanmfg.com/ Chapman Manufacturing] part CMS-10, or 5120-00-439-8271, is their 5/32 bit. Their handle lacks the forward/reverse switch (have to flip it over).
** A 5/32 hex-key socket (like [http://www.amazon.com/TEKTON-1370-Drive-Socket-Cr-V/dp/B000NPUJGM/ref=sr_1_13?s=hi&ie=UTF8&qid=1450244552&sr=1-13&keywords=5%2F32+hex+socket this]) works almost as well but is a tighter fit. Either is a huge improvement over the one that came with your last IKEA purchase. 5/32" is close enough to 4mm as to be more or less interchangeable for both pinball and flat-pack furniture assembly.

== Electrical Tools ==

*A few alligator clip leads for testing
*Digital Multimeter (DMM) with diode test function (spend more than $10.00) [http://www.radioshack.com/product/index.jsp?productId=2103176 RadioShack] or [http://www.sears.com/shc/s/p_10153_12605_03482141000P?prdNo=7&blockNo=7&blockType=G7 Sears] are among the brands. Auto-ranging meters are much easier. With meters, you get what you pay for.
*Side cutters
*Wire stripper
*For newer, solid state machines, a logic probe can be very useful. One example is an Elenco Electronics LP-560

For Connector Work, see below
 

==Pin Crimping Tools==

''Molex Crimper Styles''

[[file:Molex_Connector_Crimpers.jpg|left|thumb|alt=alternative text|Pictured from left to right, Sargent .100 crimper w/o holder, Waldom universal crimper, Sargent 1028-CT, and Sargent 3136-CT for.156 pins shown with holder]] 
Hand held crimpers for Molex style pins come in several styles, and as always, you get what you pay for. Cheaper types sacrifice ease of use, and quality of crimp and durability of the tool. A professional Molex crimper can cost more than $300, and is not necessary to do a excellent job of replacing the pins on a pinball machine. The cheapest type is the Waldom crimper for around $15, and is not recommended. The tool requires that you crimp twice, first for the bare wire, then for the insulation, increasing the chances of a bad crimp. Better is the $25 Sargent 1028-CT tool, which also must be crimped twice, but has better quality and is the only choice for .084 pins. Best are the Sargent type tools (3136-CT shown below) at about $95. These crimpers may have a holder for the pin, and also crimp BOTH the wire and insulation crimp at the same time, reducing the chances of a bad crimp. These tools are specific for the type of connector, whether that is a .156, .062, .100 pin. The .100 crimper does NOT have a pin holder. Replacement parts are also available for this style.

Saving link here:
https://www.amazon.com/HT-225D-Cycle-Ratchet-Crimping-interchangeable/dp/B007JLN93S/ref=sr_1_2?keywords=HT-225D&qid=1637339504&s=hi&sr=1-2
 

==Crimped Pin Removal Tools==

[[Image:PinRemovalTool.jpg|200px|thumb|left|Removing a round molex pin, like the .093 pins used on Bally/Williams games.]] 
Removal of round pins (.093, .084, and .062 for instance) requires a special molex tool that is quite pricey but for which there is no substitute. Each pin diameter requires the tool specific to that diameter. The key to effective use of the tool is to ensure the outer sleeve of the tool is fully "bottomed out" into the connector housing so that the pin's "locking barbs" are both released. If the tool's spring loaded center driver is pushed in before the locking barbs are released, the barbs will bind the pin into the connector housing, perhaps damaging the housing, and definitely making pin removal more difficult. 

[[Image:ReleasingTheTangOnACrimpPin.jpg|200px|thumb|left|Releasing the "locking barb" on a molex style crimp on pin.]] 
Sometimes, it's necessary to remove a pin from it's female housing. This can be easily accomplished by using a small pick or jewelers screwdriver to release the pin's "locking barb", then pulling gently on the wire. If the pin was installed with a good crimp, the pin should pull out easily. It may be necessary to install a new pin, or reshape the extracted pin's barb.

[[File:YT.png]] A brief video showing the process to remove a molex crimp style pin from a female housing can be seen [https://youtu.be/l3VMTccGLU4 here].
 

==Soldering Tools==

Soldering irons are used for both playfield wiring and board repair. While it doesn't matter much what soldering iron you use for playfield coils/wires/etc., it is critical that you use a good temperature controlled iron for PCB repair. Using a regular 40 watt iron for PCB repair will get too hot and ruin a board. If you think you will do any board repair in the future (and you probably will) you should get a temperature controlled soldering iron. The Weller WES51 and the older WES50 are good choices.

Portable:

These butane powered irons let you work pretty much anywhere. But they also get very hot, and can therefore easily overheat the joint and produce poor results. Don't use them on boards.
*Weller P2KC Professional Self-igniting Cordless Butane Iron (Best in Class) 
*Portasol Piezo 75 Watt Butane Iron (Older style Weller) 

There is also a type of cordless battery powered iron referred to as "cold heat" - these do not work well for any pinball application, due to the lack of control over the quality of the solder joint produced. Avoid these for pinball work.

Corded:
*Weller WP25 (Utility Grade)
*Weller SP23LK (Budget Grade)
*Weller W60P (temperature controlled)
*Weller TB100PK (two heat settings) - excellent, inexpensive iron / gun for soldering coils, switches, lamps, etc. - not recommended for board work

Station:
*Weller WLC100 (Consumer Grade)
*Weller WES51 (Industrial Grade)
*Weller WESD51 (Industrial Grade)
*Hakko FX-888 (Industrial Grade)

'''Advanced Soldering Irons'''

The move to lead-free manufacturing forced manufacturers to solder at a more tightly controlled, lower temperature. This requirement led to new irons that can deliver lots of heat, quickly. They have heat-up times of less than 10 seconds, and can solder larger joints than conventional irons. They have tips with built-in elements and temperature sensors. The tips show up on eBay, new and used. They are relatively expensive ($10 - $30) but last longer than regular tips. Expect to spend $200 - $400 to kit up with one of these (eBay). They are valuable if you do board work, as the fast heat delivery means the solder melts without overheating the pad.

Metcal has been making these new irons for some time, so the systems are relatively common on eBay. Metcal systems use high-frequency RF to heat the tip. JBC is a Spanish manufacturer that makes some of the best heat delivery tips out there.

Metcal MX-500P

JBC - these irons really do heat up in 2 seconds (20W handpiece)

Hakko FM series

Weller WXT series

Ersa, Goot, Pace

==Desoldering Tools==

A desoldering tool will be needed when removing a component from a circuit board. Probably the cheapest and most beginner friendly desoldering tool is a vacuum type device. This is a simple suction type device that removes heated liquefied solder. It is an excellent choice for those just starting with PCB repair or those who may only do the occasional repair.

There are also irons that are similar to a standard soldering iron with a large bulb attached to the end. The concept is that the heating of the old solder and the suction to remove the old solder is done all in one motion with one tool. The drawback to this type of iron is that you could easily apply too much heat to the board when removing a component and damage the board.

Another option are controlled desoldering stations. These are the easiest and safest to use but the most expensive option.

Here's a short list of some desoldering irons.
*Radio Shack 64-2098 - Vacuum desoldering tool. Great beginner choice.
*Aven 17535 Desoldering Pump - Cheapest desoldering type tool, most portable.
*Hakko 808 or FR-300 (newer model) - Most expensive, corded, bulky, and easiest to use.
*ECG J-045 - Basic Iron with solder sucker attached. Cheapest heated/corded desoldering tool. Not recommended for beginners.

==Rework Solder Stations==
PACE makes good systems, but they are based on legacy heating designs and are slow to get to temperature. Therefore, they are being eclipsed by new systems from companies such as JBC and Metcal.

*Pace MBT 350 (Best 3 iron station and only Class 3 approved electronics rework station. Runs micro tip soldering iron, normal soldering iron, and solder extractor simultaneously) 
*Pace MBT 301 (Best 2 iron station and only Class 3 approved electronics rework station. Runs 1 soldering iron and 1 solder extractor)
*Aoyue 2703A+ SMD repair & rework. Has soldering iron w/vacuum suction, desoldering gun, and hot air gun.

==EM Tools==
[[file:SwitchTools.jpg|200px|left|thumb|Leaf switch tools|1) Ignition points file for Tungsten contacts 2) Flexstone 3) Vendor supplied leaf switch adjustment tool 4) Homemade switch adjustment tool 5) Push-pull spring tool]] 
*Contact "points" file. You can use an automotive ignition points file from the auto parts store but ONLY on tungsten contacts. Never use this type of file on "gold flashed" contacts as found in solid state games. Doing so will ruin the switch in such a way that it will no longer be reliable.
*Flexstone file. The same cautions apply here also.
*Leaf switch adjuster tools. 

==Cleaning & Restoration Supplies==

===Recommended Supplies===

{| class="wikitable"
|+ Recommended Supplies
!Product
!Uses
!Where to get

|----
|Novus 1
|Light cleaning and polishing of plastics and playfield. Very mild abrasive.
|rowspan="3"|Most pinball suppliers carry all three grades of Novus.

|----
|Novus 2
|General cleaning and polishing of plastics and playfield. This is an abrasive that should be use sparingly.
|-

|----
|Novus 3
|Very abrasive. Cleaning for metal parts only for for evening out deep scratches in plastics.
|-

|----
|91% Isopropyl Alcohol
|Cleaning PCB boards. Displaces water. Evaporates quickly, but leaves residue behind.
|drug store (CVS, etc)

|----
|Naptha
|Cleaning off old playfield wax, cleaning off old tape adhesives/residues, cleaning off solder flux. Leaves no residue behind. Note: strong fumes listed as being carcinogenic--use with adequate ventilation.
|Hardware store; Lowes, Home Depot. Might be difficult to obtain in California.

|----
|Goo Gone
|Cleaning off various sticky residues, adhesives, and gummy glues. Main ingredient is petroleum distillates. Dissolves friction tape adhesive on backglass lift channels without harming the paint. Note that there is also a similar looking product called "Goof Off", which is not generally recommended because the main ingredient is acetone--a paint remover.
|Hardware stores; Walmart

|----
|Deoxit contact cleaner
|electrical contact deoxidizer
|

|----
|Carnauba wax (Blitz brand)
|playfield waxing; protectant for restored metal parts
|pinballlife.com, amazon, calcarcover.com, topoftheline.com, detailer365.com, serpentautosport.com, thezstore.com

|----
|Simple green
|General cleaning solution, degreaser. Not to be confused with "Mean Green", which can eat through paint.
|automotive; Walmart

|----
|Distilled Vinegar
|A mild acid (vinegar) neutralizes battery corrosion (alkaline) on circuit boards. Use a neutralizing agent before attempting repairs on boards damaged by leaking batteries. On triple-layer boards, which aren't very prevalent in pinball (Whitestar (modified) may be the only one) the alkaline can corrode the center conductor layer of the PCB making it impossible to fully neutralize. The "through holes" and "vias" on two sided boards are sometimes tough to completely clean corrosion from also.
|Grocery stores

|----
|Yellow Mustard
|Neutralizes battery corrosion (alkaline) on circuit boards. Use a neutralizing agent before attempting repairs on boards damaged by leaking batteries. Alternative to distilled vinegar to better control the area where a neutralizing agent is applied. Mustard's key ingredient is vinegar.
|Grocery stores

|----
|Tarn-X Tarnish Remover
|Used to remove tarnishing on ICs/ROMs/PROMs with silver-plated legs.
|Amazon, Walmart

|----
|Evaporust
|Used for chemically removing rust from parts. Non-toxic. Sometimes removes paint, depending on the type of paint. Most types of plastic are unaffected. Can safely be stored in tupperware or PVC piping. Evaporates over time if left exposed to air, so must be stored in air-tight containers.
|automotive; AdvancedAutoParts.com

|----
|CLR
|Used for chemically removing rust from parts. Needs to be diluted before use. Mild irritant/corrosive.
|plumbing; most hardware stores; Walmart

|----
|Mother's Mag & Aluminum polish
|For polishing metal parts with microfiber towels. Use this after metal parts have been cleaned and after rust removal.
|automotive; Walmart

|----
|Bleche white
|Used for cleaning metal parts. Might not be as effective any more since the formula changed a few years ago.
|automotive

|----
|Krylon Triple Thick
|Backglass sealant. Used for preventing further deterioration and flaking on blackglasses. 1-2 cans recommended per backglass. Not generally recommended for backglasses that are in perfect condition.
|Walmart, Amazon, various hardware stores and some pinball parts suppliers

|----
|GE Clear Silicon II 100% Silicon Caulk
|Used for protecting glass display nipples from damage. Note: "Silicon II" is neutral cure caulk. Do not use "Silicon I", which is an acetic cure caulk, as it may eat away at various materials.
|Most hardware stores; Lowes, Home Depot

|----
|Melamine sponge
|Also known as a more expensive "Magic Eraser" brand name. Use with 90% isopropyl alcohol. Used for removing varnishes/protectants on EM and 1970s/1980s playfields. Generally used prior to repainting and clear coating playfields. Use with caution--it is very abrasive and can remove paint. Remove residue from surfaces before it dries or it will cake onto the surface.
|Generics found on Amazon--however pay attention to the measurements of each sponge, since they vary wildly and some may be too small to be useful. Magic Eraser brand is found in general stores.

|----
|Hydrogen Peroxide
|Used for de-yellowing yellowed parts. Some recommendations call for Oxy to be added to the solution. Soak the parts in direct sunlight for 24-72 hours.
|Use 30%-60% solution found in hair care sections, beauty parlors, or Amazon (as "Salon Care 30/40/60 Volume") for best results. 3% solution is available at grocery or drug stores, which is less effective. Oxy is found alongside laundry detergent.

|----
|JB Weld
|Epoxy used for small patches or to fill small holes in wood.
|Hardware stores

|----
|Bondo
|Used to fill holes in cabinets and to re-shape rounded/damaged corners.
|Hardware stores, Amazon, Walmart

|----
|Fiberglass Resin
|Stronger filling material than Bondo. [https://pinside.com/pinball/forum/topic/cabinet-restoration-vids-guide Used for rebuilding damaged cabinets] with large missing pieces or missing corners.
|Hardware stores, Auto Repair stores, Amazon, Walmart

|----
|Bamboo Skewers or Toothpicks
|Used to fill stripped screw holes in playfields or cabinets. Used in concert with wood glue. After the glue is set, drill a hole of the appropriate size for the screw.
|Grocery stores, kitchen supply stores, Walmart, Amazon

|----
|Titebond II Wood Glue
|A glue used for gluing wood.
|Hardware stores, Walmart

|----
|Ziplock bags
|Can be used to store and separate parts during a tear-down. Include an index card inside the bag to label the bag of parts.
|Grocery Stores, Walmart

|----
|Index cards
|Used for cleaning switch contacts. Pinch the switch contacts together and run an index card between the contacts a few times. Can also be used to label bagged parts.
|Dollar stores, Office Supply stores, general stores, Walmart

|----
|Pink Rubber Eraser
|Used for cleaning edge connector contacts and IC pins. This is a better alternative than sanding since an eraser does not remove any of the metal material, which is already very thin. This method does not work well for cleaning header pins. If header pins need cleaning, they should be replaced anyway.
|Dollar stores, Office Supply stores, general stores, Walmart

|----
|Methylene Chloride
|Used to dissolve Loctite. Loctite can be found applied to metal screw holes (such as t-nuts) on DMD games.
|Amazon, others?

|----
|Ceramique 2 (CMQ2-2.7G or CMQ2-25G)
|Thermal compound used between components and heat sinks. Compound is not electrically conductive. Originally designed for use with computer CPUs and heat sinks.
|Amazon, newegg.com

|----
|Motsenbocker's Lift Off Latex Based Paint Remover
|Latex paint remover to remove custom paint jobs on early solid state stenciled cabinets without harming the original cabinet paint beneath it.
|Hardware stores, Lowe's

|----
|Performix Plasti Dip
|Used to coat metal parts in plastic, such as the lever handle of lockbar receivers.
|Amazon, hardware stores
|}

===Supplies to Avoid===
{| class="wikitable"
|+Supplies to Avoid
!Product
!Warnings
|----
|Mean Green
|Aggressive general cleaning solution. Tends to eat through paint. Not generally recommended.

|----
|Goof Off
|Cleaner with Acetone as the main ingredient. Listed as a latex paint remover. Eats paint. Not generally recommended as a general cleaner. Use Goo Gone or Naphtha instead to remove adhesive residue.

|----
|Liquid Silicone
|'''Not recommended''' for playfields. Silicone soaks into cracks and pores and is almost impossible to remove. Makes a playfield look shiny for a few days, then evaporates. Silicone does make the playfield slippery, but the effect is very short lived compared to real wax. If someone ever tries to clearcoat the playfield, it will be filled with fisheye defects. If someone ever sands the playfield, the dust with the silicone can infect the entire shop.

|----
|Millwax
|Outdated product for pinball use. '''Not recommended''' for playfields. It is liquid silicone and does not actually contain wax, which makes things slick, but offers no protection. The silicone will cause problems for the clear coating process (fisheye defects). Leaves white liquid residue behind. Fills cracks with white residue. Williams issued a warning bulletin in 1989 about using cleaners with petroleum distillates, such as millwax and wildcat, because it destroyed the adhesive on mylar and caused the mylar to lift from playfields.

|----
|Cleaner Wax
|'''Not recommended''' for playfields. Any wax that claims it is also a cleaner will contain strong solvents abrasive particles used to try to scrub down to fresh layer of paint on a dull, faded automobile. This will wear down the playfield with every use and cause significant damage.

|----
|Pledge
|'''Not recommended''' for playfields. Pledge is a mixture of Paraffin Wax and silicone. Paraffin is a very soft wax and offers no actual protection. The shine and slickness of pledge will only last for a few days.

|----
|Liquid Wax
|'''Not recommended''' for playfields. Liquid Waxes that are simply "wipe on - wipe off" products are just silicone, fast evaporating solvents and a tiny suspension of paraffin wax. Leaves a very dusty residue after it dries, which ends up being a big mess that needs to be cleaned up. Offers little to no actual protection. The silicone causes problems with the clear coating process (fisheye defects). Shine and slickness are very short lived.

|----
|Wildcat
|Outdated product for pinball use. '''Not recommended''' for playfields. Wildcat is a mixture of super strong solvents, petroleum distillates, and silicone, which was recommend by Bally in their manuals at one time. The strong solvents would soften the topcoat allowing the cloth to free ground-in coil dust. The strong solvents will cloud plastic ramps should it accidentally come in contact with them. Don't EVER allow Wildcat to touch anything plastic. Never use Wildcat on a modern pinball playfield with automotive clear coat. Williams issued a warning bulletin in 1989 about using cleaners with petroleum distillates, such as millwax and wildcat, because it destroyed the adhesive on mylar and caused the mylar to lift from playfields.
|-

|----
|Any products with Petroleum Distillates
|'''Not recommended''' for pinball use. The strong solvents will cloud plastic ramps should it accidentally come in contact with them. Don't EVER allow it to touch anything plastic. Never use Wildcat on a modern pinball playfield with automotive clear coat. Williams issued a warning bulletin in 1989 about using cleaners with petroleum distillates, such as millwax and wildcat, because it destroyed the adhesive on mylar and caused the mylar to lift from playfields.

|-----
|Blue Magic Metal Polish
|'''Not recommended''' for pinball use. Contains silicone. The silicone causes problems with the clear coating process (fisheye defects). Protection, shine, and slickness are short lived since the silicone film doesn't last long in a pinball environment. For metal playfield parts, it is better to polish, then for protection, wax with carnauba wax, or seal with clear coat or polyurethane.
|}

[[File:Williams-bulletin-petroleum-distillates-warning.gif|thumb|200px|left|Williams warning bulletin about using waxes/cleaners with Petroleum Distillates, such as millwax and wildcat.]]
 

==Lubrication==
In nearly every instance, lubrication should not be used. The exceptions are metal on metal mechanical points (stepper unit pivot points, stepper unit wipers, and the pivot points of '''very few''' mechanical assys.). Although Williams stated to use graphite powder for lubrication on coil plungers where aluminum or brass coil sleeves were used, it is best to just replace the metal coil sleeves with new nylon sleeves ('''Note:''' some brass coil sleeves are integral to the coil's winding, and are not removeable). A general rule of thumb is where metal makes contact with plastic, lubrication is not needed. However, if lubrication is necessary, Super Lube Teflon gel is a very good product to use. However, it should be used very sparingly. When in doubt, under lubrication is better than over lubrication. 

[[File:WD-40 01.JPG|200px|thumb|left|WD-40 needs no introduction]]
[[File:WD-40 Coin Door.JPG|200px|thumb|right|Removal of Coin Door Sticker Residue with WD-40]]
'''In no instance should WD-40 be used as a lubricant!''' WD-40 is a great product, but should used as intended. It can be used for breaking apart seized screws, bolts, or associated mechanisms, but should thoroughly be cleaned off once a unit has been disassembled. It is also an excellent way to keep surface rust from forming on pinballs (the ball itself) in storage, but make sure to clean thoroughly before installing in a machine. 

There is one other good use for WD-40 regarding pinball machines. Coin door stickers, operator stickers on aprons, and game permit stickers all tend to make their way onto pinball machines. WD-40 is a very good product which can be used to remove sticker residue.
It also makes an excellent hand cleaner.
 

==Building a flexible power supply for bench testing PCBs==
In work

=How to Twist Wires Together Neatly=
Easy as Pie...
#Chuck both wires in a slow speed drill
#Hold other end firmly
#Engage, and watch with amazement as the wires neatly twist around each-other.
As you can see from the results below, this old technique yields excellent results.

<center>
<gallery widths=300px heights=200px perrow=3 caption="How to neatly twist two (or more) wires together">
File:WireWindingStart.jpg|<center>Chuck the wires</center>
File:WireWindingEnd.jpg|<center>End result</center>
File:WireWindingDetail.jpg|<center>End result detail. Nice...</center>
</gallery>
</center>
 

= Repairing Wiring Damaged by IDC Connectors =

IDC (Insulation Displacement Connectors) were used by all pinball manufactures for no other reason but to speed production. It was much faster/cheaper to "punch" wiring into an IDC connector than to crimp pins onto the wires then insert the crimped pin into a connector. IDC connectors are inferior to crimp pin connectors if reliability and connection quality is the main concern.

Sometimes the wiring at the IDC connector becomes pulled, frayed, etc. The wiring should be repaired to ensure a good connection. One method is shown in the picture gallery below.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Repairing Damaged Connector Wiring">
File:RepairingFrayedIDCWiring1.jpg|<center>The "problem"...the wire insulation has been compromised.</center>
File:RepairingFrayedIDCWiring2.jpg|<center>Heat shrink tubing in place, the wires have been twisted together and soldered.</center>
File:RepairingFrayedIDCWiring3.jpg|<center>Heat shrink tubing has been shrunk and the joined wire has been "punched" into the IDC connector using a proper punch tool. The wire with orange tracer will be repaired next.</center>
</gallery>
</center>
 

= Repairing Broken IC Legs =

Sometimes the leg of an integrated circuit will break off.

If the "meaty" part of the leg remains, repair is not difficult.

If the pin breaks at the point where it enters the chip carrier plastic, the same technique detailed below can be used, but part of the chip carrier plastic will need to be removed with a Dremel to expose enough metal so that the donor leg can be attached.

<center>
<gallery widths=300px heights=300px perrow=2 caption="Repairing Damaged Integrated Circuit Leg">
File:IC-LegReplacement-1.jpg ‎|<center>The "problem"...the thin part of the top chip's leg has broken off. The lower chip will provide a "donor leg".</center>
File:IC-LegReplacement-2.jpg ‎|<center>The broken leg is tinned with a small amount of solder. The donor leg is positioned in a spare socket.</center>
File:IC-LegReplacement-3.jpg ‎|<center>The IC is inserted into the socket with the donor leg in the proper position. The leg is then heated until the solder melts and the donor leg "wicks" to the existing chip leg.</center>
File:IC-LegReplacement-4.jpg ‎|<center>The completed repair is quite durable.</center>
</gallery>
</center>
 

= Connector Headers and Housings =

Solid electrical connections between connectors and header pins are essential to the proper operation of a game. Heat damaged or worn out connectors (and they do have a service life) increase electrical resistance, which causes more heat, which causes more resistance, etc. Ideally, the connection of a female housing to a male header pin will measure zero resistance, just like a short length of wire would.

[[Image:RuinedHeader.jpg|200px|thumb|left|Dual row header pins from a Sega DMD Controller. These pins were ruined in an attempt to sand alkaline corrosion from the pins. Replacement is the only option.]] 
It's tempting to remove corrosion or tarnish from male header pins by sanding them. While this will remove the corrosion, it also ruins the long term reliability of the header pins as can be seen in the picture at left. Header pins typically have a mate/unmate life limit. Sanding header pins exhausts all of this life limit.

Most modern pinball manufacturers used IDC connectors (Insulation Displacement Connector). When connector replacement becomes necessary, crimp-on pins and housings are preferred to IDC connectors. IDC connectors were originally used to increase the speed of manufacture, at the expense of long term reliability. While replacing IDC connectors with new IDC connectors can certainly return a game to operation, a better solution for long term reliability is to use Trifurcon crimp-on pins where possible. Trifurcon pins form a much better electrical connection to the male pin and the crimp forms a much better electrical connection to the wire. A variety of crimping tools may be used, but nothing other than a crimping tool should be used (i.e. don't use needle nose pliers). Get the right tool for the job.

.156" IDC housings used in Williams and Bally games cannot be reused with crimp connectors. However, Gottlieb .156" IDC housings can be reused. .100" IDC housings cannot be reused regardless of the pinball machine manufacturer. 

[[Image:OriginalIDC.jpg|200px|thumb|left|An OEM IDC connector at J101 of a Williams WPC Power/Driver board.]]
[[Image:IDCRepinned.jpg|200px|thumb|right|A replacement IDC connector, also used at J101 of a WPC game.]] 
Many modern games "loop" a wire through an IDC connector, making a connection between the wire and two pins. This is easily done with an IDC connector as shown in the left image of an OEM IDC connector and as shown in the right image of a replacement IDC connector that has been stuffed.
 

[[Image:RepinOption.jpg|200px|thumb|left|One alternative to "looping" a wire through a connector is "forking" the wire.]]
[[Image:TwoPinsCrimped.jpg|200px|thumb|right|Another alternative to "looping" a wire through a connector. In this image, the 3rd position form the bottom and the top position have two wires crimped into a single pin.]] 
Using crimp-on pins, there are two options to connect a wire to two separate pin positions.

The first option is to "fork" the wire into two conductors as shown in the picture at left. While this is time consuming, it does make an effective and solid electrical connection. Strip about 1/4" of insulation from the wires. Position adequately sized heat-shrink tubing. Solder the three wires together. After the solder junction cools, move the heat-shrink into place and shrink it. Crimp pins are easily crimped to the single wires.

The second option is to crimp two wires into a single crimp pin. The technique for this is shown at right. This is certainly an effective method. Crimping two wires into a single crimp pin is the most difficult task. Generally, more insulation should be stripped back, the wires twisted tightly together, and the crimp pin positioned to cover all of the exposed wire. With a little practice, this is easily accomplished.
 

=Connector Designations=
Connectors/jacks/plugs tend to have a P or J prefix assigned to them. A connector in a fixed location (such as on a circuit board) is normally referred to as a jack, while a movable connector is a plug.

Jacks use the reference designator prefix of J and plugs use the reference designator prefix of P. For example, if a PCB has a label of J5 on it, it essentially means that the connector on the board is designated as "Jack 5".

When a male and female plug are connected together, each side is considered a plug--however, the male side typically uses the designation of J and the female side typically uses the designation of P.

= Making a "Universal Lock" =
[[Image:UniversalLock.jpg|200px|thumb|left|Closeup of a typical pinball lock plug, with "keying pins" still in place.]] 
Locks that are "keyed alike" are a great idea for the hobbyist with many games. Another option, is to create a "universal lock". The procedure is simple. Remove the screw that holds the lock tang in place along with the lock tang. Pull the "plug" assembly from the "hull" (see picture at left). Use a beefy pair of needle nose pliers to yank the (typically) brass "keying pins" out of the plug. Shake the tiny springs out of the plug too.

Reinsert the plug back into the hull, then screw the tang back onto the lock. All that is needed now is a flat blade screwdriver to open your game.

This is a great option for EM game backbox locks.
 

=Soldering & Desoldering=

Soldering is a simple thing, but requires a little practice and some knowledge to master. In a pinball machine, there are two kinds of soldering. One is wires to lugs - coils, lamps and switches. The other is board soldering.

[https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1 A very good guide on an introduction to soldering is available here].

NOTE: If you aren't confident with your technique, practice on something else first! Soldering is an 'art' in some respects (I like to think of it as mini-welding) so grab an old circuit board and get practicing!

==Equipment and Supplies==

===The basic soldering iron===
A $15 Radio Shack 25W soldering iron will work for some applications. However, a good temperature controlled, rapid heating iron is something you should consider if you do much soldering and certainly if you are soldering on printed circuit boards. Many manufacturers offer great irons. One example is the Weller WESD-51.

===Tip Cleaner===
For years, a wet sponge has been used for this purpose. Most times, the sponge is integrated into the solder station stand. Many techs now use the "wad of coils of brass" like the Hakko 599B-02 (pronounced "Hock-O"). This eliminates the need to dampen the sponge before each soldering session.

===Solder===
There are three things that matter with solder.

The diameter. In pinball, .031" is a good general purpose size. Thicker, and you'll be blobbing everywhere except on the biggest joints. Thinner, and it takes a lot of solder to feed a joint.

The alloy, typically tin-lead, expressed as something like 63/37, which means 63% tin and 37% lead. For pinball, 63/37 is the best overall alloy. The common 60/40 is a shade cheaper, but isn't as good. In particular, it goes through a pasty mode before it hardens. If it is moved while pasty, you can get a bad joint. You can use 60/40, but 63/37 is more reliable. You won't like lead-free solder, as it has to be hotter and does not flow as well. Plus, even good joints look frosty.

The flux, which might be rosin, no-clean or water soluble. You don't want water soluble, as it can leave an acid residue if not washed. No clean is nice, as it doesn't leave blobs of flux hanging on a joint. Rosin, the classic flux, is aggressive and effective, but leaves joints dirty and should be cleaned with alcohol when used on boards.

A fourth parameter is the number of solder cores, typically 50 - 66. Doesn't matter for pinball, but a higher core count should be a little easier to use.

So you will want one of these two types:
*Rosin-core .031 63/37 (e.g. Kester 24-6337-0026). This is super easy to use and will get you the best joints (AKA Kester 44)
*No-clean .031 6337 (e.g. Kester 24-6337-8801). Easy to use, no cleaning needed (AKA Kester 245).

If you want to get solder locally, Radio Shack sells a nice .032 diameter 60/40 rosin-core solder, Radio Shack part number 64-009.

As the industry transitions to "lead free solder" (RoHS compliant), leaded solder will become increasingly more expensive and hard to find. However, the US still has few restrictions on the use and sale of leaded solder.

Kester 245 "no-clean" solder (24-6337-5400 with an obsolete 50 core count) can be found from several suppliers.

Mouser also carries a good range of 63/37 solders
[http://www.mouser.com/Tools-Supplies/Soldering/Solder/_/N-b11qq?P=1yzt5jhZ1yzxbyq Mouser 63/37 solders]

'''Under no circumstances should Acid-core (plumbing) solder be used anywhere on a pinball machine.'''

===Optional Equipment===
*Small tweezers or clamps such as [http://www.amazon.com/Copernicus-Handy-Magnifier-Alligator-Clips/dp/B003VD36IG My Handy] - Great for a helping hand during soldering jobs.
*[http://en.wikipedia.org/wiki/Crocodile_clip Crocodile clips] to make temporary connections and testing easier.

==Soldering wires==
We'll start with wire soldering. You'll need this skill to replace micro-switches, coils and lamp sockets. The good news is that you cannot do much damage. Just be careful about where you put the iron, watch for solder splashes or drips, and try not to overheat anything.

Here are the simple steps:

#You'll need to tin the iron, the wires and lugs before you make the joint. Tinning gives you fresh solder on the joint surfaces and helps make a good connection.
#Wait for the iron to heat up fully (about 700 degrees F) and apply a little touch of solder to the iron, then swiftly wipe the tip clean with your tip cleaner. This "tins" the iron.
#Touch the iron to the wire. Put a tiny dab of solder between the tip and the wire, so that it melts into the wire to help transfer the heat from the iron. Feed more solder to the hot wire (not the iron) until it has a "coating" of solder. This "tins" the wire. Take care to not apply so much heat that the insulation on the wire melts.
#Place the wire(s) and lugs together, and touch the iron to the joint. The solder will melt, and flow across the joint. You can add more solder at this point. As soon as the solder has run, Remove the iron and let the joint cool.

As the joint cools, the wire that you are holding will heat up as the heat conducts through the wire. You will discover that it may take 5 or more seconds for the solder to harden. The wire may become too hot for you to comfortably hold, and this is where small tweezers or "hemo-stats" are useful. Regardless of the method used to hold the wire, it is important to keep the wire from moving, until the solder takes a solid form again. If the wire is moved, you may have created what is referred to as a cold solder joint. The result of a cold solder joint will be a weak connection or a connection which will fail prematurely. A good way to determine whether or not the joint is secure after soldering is to gently tug on the wire after the joint has cooled.

'''Things to Know'''

*Solder flows to the heat. If you apply solder to the iron, the solder won't flow to the wire/lug and the solder joint will be unreliable.
*It takes a lot of heat to make solder turn from solid to liquid. While it is melting, the temperature does not rise. Once the liquid runs through the joint, you should pull the iron away to avoid overheating.
*Some techs will "tack solder" wires to lugs, melting solder on the wire to solder on the lug. Other techs suggest that a good solder joint begins with a good "mechanical joint". They suggest that threading the wire through the coil lug (for instance) will create a stronger, longer lasting joint. Whichever method you choose, good looking solder joints begin with clean lugs and clean, freshly stripped wire.

== Soldering on Printed Circuit Boards ==
Soldering components onto printed circuit boards is a bit more delicate than general soldering. The need for a good temperature controlled iron, an appropriate soldering iron tip, and good solder is even more important. 

Solder pads on pinball printed circuit boards are delicate and can become damaged each time heat is applied to them. If too much heat is applied for too long, especially on single sided boards, the pad will lift off, making the repair much more difficult. It is better to use more heat for less time than less heat for more time. 

When the replacement of a chip is necessary, it is recommended to use a chip socket (in most all instances - there are some exceptions), versus soldering a replacement chip directly onto the circuit board. The reasoning is two-fold:

# Adding a chip socket reduces the amount of heat applied to a circuit board in the future should the same chip fail.
# If the same chip does fail, replacement of the chip will be much easier.

When soldering a chip socket in place, skipping from side to side for subsequent joints or skipping every other pin as you solder can help alleviate the risk of heating up a small part of the board, causing lifted pads and traces. A good solderer with the proper equipment can solder a 40 pin chip socket into place on a PCB in about 2 minutes. 

The best solder joint on a PCB is achieved when the solder "flows" into the "through-hole". Of course, this won't happen on single sided boards since there is no copper trace to flow to. 

[[File:Socket check work.JPG|200px|left|thumb|Testing for (lack of) continuity between chip socket positions]]
[[File:MessySolderFlux.jpg|200px|right|thumb|Flux residue continues to "etch" bare copper traces if left on the board. In the picture at left, flux residue ate through the circled trace, severing the trace completely. The trace is in the GI circuit of a WPC-089 Power/Driver board.]] 
After a chip socket has been soldered onto a board, it is equally a good practice to check for continuity between the socket pin and the adjoining circuitry, and discontinuity between adjacent socket positions. If there isn't continuity between the chip socket and its associated circuits, check / inspect the work performed. Likewise, if there is continuity between neighboring chip socket positions, check for excess solder or foreign material creating a conductive bridge between the two. 

'''Note:''' in some cases, a PCB has traces or pads intentionally tied together between adjacent chip sockets. Consult the schematics of the particular board being worked on to verify if this is the case, when two sockets are determined to have continuity.

Clean Up Flux Residue

From Wikipedia: The role of flux in the joining processes is typically dual: dissolving of the oxides on the metal surface, which facilitates wetting by molten metal, and acting as an oxygen barrier by coating the hot surface, preventing its oxidation. In some applications molten flux also serves as a heat transfer medium, facilitating heating of the joint by the soldering tool or molten solder.

Once you've made an awesome solder joint, clean up the corrosive flux residue that remains behind. Even "no clean" flux leaves residue that should be cleaned up, if only to provide evidence that a professional repair job has been done. Denatured alcohol, naptha, and many other mild solvents can be used. Products specifically manufactured for flux removal are usually quite expensive, but would obviously work well.
 

=== Bending Discrete Through-hole Components ===
[[File:BendingThroughHoleComponents.jpg|200px|left|thumb|A convenient way to bend through-hole components using a drop target.]]
[[File:ComponentBender.jpg|200px|right|thumb|An example of a purpose made component bending tool.]] 
An easy way to bend resistors, capacitors, etc to length when replacing them is to use a popsicle stick or an old drop target, as pictured at left. Bend the leads around the target. This works well for many older game systems like Bally -17/-35, Williams, etc.

And then there is the tool that is specifically designed for the job (right).
 

===Repairing traces or creating a "solder stitch"===
Sometimes as a result of applying too much heat to a solder pad, the pad or the trace will lift. Sometimes when removing a "snap cap" from a WPC Power/Driver board (for instance), the odds of cracking a through-hole are high since installation of the snap cap originally damaged the through-hole at least some.

A good way to repair this kind of damage is to use a "solder stitch" as pictured.

[[Image:SolderStitchSteps.jpg|300px|thumb|right|Repairing Traces Using a Solder Stitch]] 
'''Procedure''': 
#Sand or scrape some of the damaged trace on both sides of the board so that you can solder the "stitch". 
#Twist 3 strands (or so) of copper wire together. Give yourself enough wire to work with. Usually, about 1/2" will be enough. 
#Place the stitch through the through-hole and bend it tight to one side to be stitched. Inserting a small "pick" into the hole will help with placement of the stitch wire. 
#Solder the component side of the stich to the trace. 
#Install the new component (or socket). 
#Flip the board over. 
#Wrap the excess stranded wire around the component leg.
#Solder the stitch wire to the component leg and the PCB.
#All done!
 
[[File:YT.png]] A video of the procedure being performed on a WPC Power/Driver board C5 capacitor location can be viewed [https://youtu.be/ztuosZQVDFU here].
 

===Using an old Socket to Align SIPs and Headers===
[[File:UsingAnOldSocketToPositionSIPs.jpg|200px|left|thumb|Using a socket to align SIP (Single Inline Package) machine pin socket strips.]]
[[File:UsingAnOldSocketToPositionHeaders.jpg|200px|right|thumb|A convenient way to align header pins across two header strips.]] 
Using an old socket to position two SIPs perfectly is easy, as shown in the picture at left.

Likewise, an old socket can be used to position headers perfectly in line when more than one header strip is used/needed, as shown in the picture at right.
 

== Desoldering Printed Circuit Board Through Hole Components ==

There are several methods of desoldering through hole components from printed circuit boards. The average home hobbyist should typically send boards in need of repair to a professional board repair technician. If you already know about desoldering irons like the Hakko 808 or 472, then you probably don't need the following advice.

The simplest way to desolder almost any through hole component from a PCB is to cut the part from the board, leaving enough of the legs to individually heat and remove. The through hole can then be cleaned with one of various "solder suckers", solder wick, or even heating the hole and blowing compressed air through the hole (caution is advised).

The key to avoiding damage to PCB solder pads is to use just enough heat, for just enough time. Only practice will help you find the right technique.

The three steps to desoldering a through hole component are shown in the picture gallery below.

[[File:YT.png]] A YouTube video demonstrating this method can be found [https://youtu.be/iTUbd3W7ipg here].

<center>
<gallery widths=300px heights=300px perrow=3 caption="Easy removal of a through hole component. This example is a TIP-122 transistor on a Sega/WhiteStar Power/Driver board.">
File:TransistorClipped.jpg|<center>Clip the part off with a sharp pair of side cutters.</center>
File:HeatEachLeg.jpg|<center>Heat each individual leg and remove with a needle nose pliers, or even the side cutters. A slender iron tip like this one makes the job much easier.</center>
File:CleanUpHoles.jpg|<center>Clean up the through holes with your preferred solder sucker. The technician here is using a Hakko 472.</center>
</gallery>
</center>

[[Image:AddSolderToDesolder.jpg|300px|thumb|left|Note the small amount of solder added to the pins left of the yellow line. Compare them to the other pins in the picture. This makes desoldering much easier.]] 
Many manufacturer's boards were soldered with very little "excess" solder at the through hole, like the WhiteStar DMD Controller pictured left. While perfect for original manufacture, the small amount of solder available to heat with a Hakko 808 or equivalent solder sucking tool, makes desoldering difficult. The simple trick is to add a small amount of solder to the joint before attempting to desolder the joint.
 

[[Image:PartRemovalIndicators.jpg|300px|thumb|left|A 62256 RAM on a WPC MPU board, with a bit more solder to clean from the through holes before attempting removal]]
[[Image:DontPryPartsUp.jpg|300px|thumb|right|Damage caused by prying with a screw driver. Ouch!]] 
If you've sucked or wicked all of the solder from the trough holes, the part will generally come loose with just a bit of coaxing. Exceptions are alkaline corroded parts or just about anything on a Gottlieb System 3 board (very tight through holes). In the picture at left, most of the holes are clean enough to attempt removal. On the lower edge of the chip, pins 2 through 4 from the left, too much solder remains in the through hole to attempt removal. Add a little solder to the joint from the solder side, then clean the hole again.

Under no circumstances should the part be "pried" from the board. Doing so creates a significant risk of fracturing a PCB trace. In the picture at right, a well meaning hobbyist attempted to pry the 6264 RAM from a WPC-089 MPU board while installing NVRAM. This is a super Corky no-no.
 

=Desoldering Snap Caps=
[[file:PulledThroughHole.jpg|200px|thumb|left|A good view of a 15,000uf cap, with a pulled through hole still on the left lead (the brown donut looking object)]]
Removing the large 10,000 or 15,000uf capacitors from pinball PCBs is not trivial and probably shouldn't be attempted by most home pinball enthusiasts.

Also, some vendors provide "cap kits" that do not match the physical size of the original caps. Tall slender capacitors mounted horizontally on a pinball PCB is not a good idea since the vibration environment is quite harsh and fractured solder joints will occur over time.

"Back in the day", the advice dispensed most often was to heat one lead, rock the cap to the side, heat the other lead, rock the cap to the other side, continue until the cap can be pulled free. Unfortunately, in addition to removing the snap cap, often the PCB through holes would be removed also, appearing as "brown donuts" around the snap cap leads as shown at left. Using this old school technique is highly discouraged.

Instead, add solder to both snap cap leads. Heat both leads simultaneously, either with a solder tip wide enough to reach both leads, or with two soldering irons (it's good to have a friend, or three hands, your choice). When the solder becomes molten on both leads and all the way through the through hole, the cap can be gently extracted.

[[File:YT.png]] A video demonstrating an excellent technique for removing snap caps can be found [https://youtu.be/rs90-UMtCww here].

 

=DIP (Dual In-line Package) Pin Numbering Convention=
[[File:Dip14pins.jpg|200px|thumb|left|A typical 14 pin Dual Inline Package (DIP)]]
[[File:ICNumberingExample.jpg|200px|thumb|tohjy|Don't rely on IC labeling. Look for the "dot" or the "notch". Image courtesy of John Wart Jr.]] 
The diagram at left shows standard pin numbering for integrated circuits. Pin 1 is always located at the chips "dot" or if the chip does not have a dot, immediately to the left of the chip's "notch". The pin "legs" are then numbered sequentially around the chip counter-clockwise. This convention is observed for DIP packages of all sizes.

Never rely on the ICs printed label. As shown in the picture at right, an IC might be labeled completely reversed from the identical chip from the same manufacturing facility.
 

=Sockets=

Sockets are used to secure integrated circuits to printed circuit boards, without soldering the IC directly to the board. They are well advised when doing any kind of IC replacement. By using a socket, PCB damage caused by repeated desolder/solder cycles is avoided.

[[File:ExampleSockets.jpg|200px|thumb|left|(L to R) Examples of a 20 pin "break to length Machined Pin SIP socket, a closed frame 40 pin machined pin socket, and a 24 pin twin leaf open frame socket. Note the "notch" on one end of the DIP sockets, which should be oriented relative to "pin 1".]] 
There are two basic kinds of sockets widely used on PCBs.
*Machined Pin Sockets
*Twin Leaf Sockets (also called "dual wipe")

"Open Frame" refers to the construction of the socket. As you can see in the picture at left, closed frame sockets do not provide a "view" through the center of the socket. For this reason, open frame sockets are generally preferred.

Sockets, like connectors, have a typical insertion/removal cycle specification. Opinions vary on which style is preferred. Some say that the life expectancy of machined pins sockets is shorter than twin leaf sockets, and that the machined pin socket connections sometimes become marginal. Machined pin sockets generally form more reliable or solid solder joints to the PCB, which is nice unless the socket needs to be removed. Twin leaf sockets are much easier to remove once installed. Machined pin sockets are easier to use as "risers" (soldered just above the PCB) when the PCB solder pads have been damaged and soldering on the "component side" of the board is necessary. This technique is especially effective when combined with SIP (single inline package) machined pin sockets.
 

[[File:MarginalSocket.jpg|200px|thumb|left|A damaged twin leaf socket. Note pin 5.]]
[[File:MarginalSocketCloseUp.jpg|200px|thumb|right|Closeup of damaged socket pin. Note that one of the twin leaves is irreparably bent. This pin caused intermittent operation.]] 
Twin leaf sockets are easily damaged if something dimensionally larger than an IC leg is inserted into the socket. In the picture at left (and in the closeup (right), a damaged aftermarket replacement socket on a WPC MPU (for an LM339) caused intermittent issues with the switch matrix.
 

=Logic Probes=

'''Overview'''
[[Image:Hi-logic-level.gif|200px|thumb|right|High logic level.]]One of the simplest and cheapest tools you can include in your test equipment arsenal is a logic probe. Although a lot of people seem overwhelmed by logic probes, they are actually very easy to use. In regards to their purpose, consider a logic probe as a bridge between a meter and a scope.

While a meter is great for reading constant voltages (see image to the right) they fall short when a signal is pulsed (see second image to the right, which is a 12 volt pulsed signal from the switch matrix). What the meter will try to do with this signal is average it and give you a single voltage reading, which is not very helpful. Of course a scope works great on pulsed signals, but is much more expensive, and complicated.

[[Image:Pulsed-logic-level.gif|200px|thumb|right|Pulsed logic level.]]Specific to pinball, both the lamp and switch matrices are pulsed, plus circuits on the cpu, display and sound boards. While you can infer readings from the switch matrix, for example, using a meter it is much easier to just use a logic probe.

The official version of this article is: [https://pinside.com/pinball/forum/topic/terrybs-guide-to-logic-probes TerryB's Guide To Logic Probes (on Pinside)]

'''Buying a Logic Probe'''

[[Image:Elenco-560.jpg|200px|thumb|left|Elenco 560 logic probe.]]In the image to the left you can see my recommended logic probe, the Elenco LP-560, available at Amazon for $17. You can spend more, but this is really all you need. In addition to all of the standard features (which we'll discuss more in a little bit) it also provides an audible tone in addition to the led's. While this will not benefit you much initially, as you become more proficient there are times when the audible tone provides a better indication of a pulsed circuit than the leds.

The only function that it does not have is a pulser, which allows you to apply a signal to a circuit. This is a fairly advanced technique and most hobbyists will never have need for it. 

'''Logic Families'''

Note: The information in this section has been simplified in order to align with the goal of a beginner level guide. For example, both CMOS and TTL gates have different input and output logic levels, although we will consider them as being the same for our purposes. While not necessary, if you want to fully understand the differences between TTL and CMOS logic levels see the following article at All About Circuits.

http://www.allaboutcircuits.com/textbook/digital/chpt-3/logic-signal-voltage-levels/

There are different logic families, or generations, of integrated circuits. Each logic family has different behavior and within each logic family there can be subsets with different characteristics. The only two we need to be concerned with in regards to our discussion are TTL and CMOS.

TTL chips use a nominal Vcc (Vcc is the fancy term for the supply voltage) of 5 volts and the inputs and outputs are always binary (low, high or pulsed). TTL chips typically, but not always, use a standard naming convention of 54XX or 74XX.

On the other hand, CMOS chips can use a Vcc ranging from 3 - 15 volts and depending on the chip can have either binary (low, high or pulsed) or analog inputs and outputs. CMOS chips typically, but not always, use a numbering convention of 40XX or 45XX.

One example of CMOS in a pinball machine is the LM339 voltage comparator used in Williams/Bally switch matrix circuits. We'll discuss this in more detail as we get into the switch matrix example, but for now the important part is to be able to recognize whether an IC is TTL or CMOS. If in doubt, you can always check the datasheet for any given IC.

Based on the logic family of the chip there are different voltage ranges that are considered to be low or high in a digital circuit. In the case of TTL the low range is 0 - .8 volts and the high range is 2 - 5 volts. So any reading between 0 and .8 volts is considered a logic 0 and any reading between 2 and 5 volts is considered a logic 1.

The specification for CMOS circuitry in a 5 volt circuit is a low range of 0 - 1.5 and a high range of 3.5 - 5. For a 10 volt Vcc the low range would be 0 - 3 volts and the high range 7 - 10 volts. The high and low voltage ranges scale linearly across the possible supply voltages of 3 -15 volts.

Thankfully you don't need to remember all that though, since there is a TTL/CMOS switch on the Elenco (and in fact all logic probes except for those that are auto-sensing). Put the switch in the correct position (based on the previous information about CMOS and TTL) and it will correctly read low and high signals for that logic family.

'''Logic Probe Features'''

[[Image:Elenco-indicators.gif|200px|thumb|left|Elenco status indicators.]]The first thing you will notice is that the logic probe has two wires (red and black) with alligator clips at the end. This is where the probe gets it's power and they must be connected to ground and supply voltage. If you're testing a 5 volt circuit, the red lead goes to 5 volts and the black lead to ground. If you're testing a 12 volt circuit (parts of the switch matrix, for example) the red lead goes on 12 volts and the black lead on ground.

The pointy thing at the other end from the two wires is the probe. Unlike a meter this single probe is all you need to take your readings.
There are two switches, TTL/CMOS and MEM/PULSE, that will need to be set properly.

If you're analyzing a TTL chip, put the TTL/CMOS switch in TTL and when checking a CMOS chip, put the switch in CMOS. The MEM position on the MEM/PULSE switch will capture a pulse and retain the reading, which is advantageous in some rare situations, but for our purposes here you want it set to PULSE.

[[Image:Logic-probe-readings.png|200px|thumb|left|Elenco status indicators.]]The last, and most important part, of the logic probe are the HI/LO and PULSE led's. The red (HI), green (LO) and yellow (PULSE) led's are used to indicate the state of the measurement point. Note: Some logic probes use different combinations of lights to indicate the status, so just a reminder, we're specifically talking about the Elenco logic probe here.

In the first image to the left you can see the various signals that can be indicated by the led's. In most cases you can narrow these down to three issues: is the line high, is the line low or is the line pulsed. The next image on the left provides another representation, comparing the led's to what you would see on an oscilloscope. 

'''Switch Matrix Example'''

Now let's look at a real world example (Williams WPC in this case, but the theory is the same on other games) to see how the logic probe works when testing the switch matrix. Note: It is beyond the scope of this article to cover how the switch matrix works. See the following link for more information on the switch matrix: [[General#The_Switch_Matrix| Switch Matrix]].

The image below provides a generic WPC switch matrix circuit and we'll walk through what each test point should look like, starting with the column, or send, signals.

[[Image:Switch-matrix.png|800px|center|WPC switch matrix circuit.]]

The ULN2803 is a TTL chip that uses 5 volt logic on the input (point B) and controls a 12 volt signal on the output (point A). So the logic probe should be set to TTL and the red lead connected to 5 volts when testing inputs and 12 volts when testing outputs.

Tip: If you look at the image below you will see three red circles with pull-up resistors and a supply voltage within them. If the pull-up resistor is connected to a 5 volt supply you know you are working on a 5 volt circuit and if it's connected to a 12 volt source you know you're working on a 12 volt circuit.

[[Image:Pull-up-resistors.png|600px|center|WPC switch matrix pull-up resistors.]]

With our logic probe connected to 5 volts and the probe on point B we will get a green light and the yellow light will be pulsing. This indicates a low signal with high pulses. This signal is a constant timing pulse and will not change based on the status of the switch.

The circle shown at point A tells us that the output signal from the ULNL2803 is inverted. So a high input provides a low output, and a low input provides a high output. Therefore, with our logic probe connected to 12 volts and the probe on point A we will get a red light and the yellow light will be pulsing. This indicates a high signal with low pulses.

The row side gets slightly more complex and the readings will change based on the status of the switch. The first part of the circuit we are concerned with is the LM339. It is a CMOS chip that takes a 12 volt signal on the + input (point C) and provides 5 volt logic on the output (point D). So the logic probe should be set to CMOS and the red lead connected to 12 volts when testing inputs and 5 volts when testing outputs.

With our logic probe connected to 12 volts and the probe on point C we will get a red light with the switch open, which indicates a high reading. With the switch closed we will get a red light and the yellow light will be pulsing. This indicates a high signal with low pulses.

With our logic probe connected to 5 volts and the probe on point D we will get a red light with the switch open, which indicates a high reading. With the switch closed we will get a red light and the yellow light will be pulsing. This indicates a high signal with low pulses.

The 74LS240 is a TTL chip and since there is a circle on the output we know that the signal is inverted. So with our logic probe set to TTL, connected to 5 volts and the probe on test point E we will get a green light with the switch open and a green light with the yellow light pulsing with the switch closed. The former indicates a low reading and the latter a low reading with high pulses.

The image below provides a graphical representation of the logic probe led status for each test point.

[[Image:Switch-matrix-readings.png|690px|center|WPC switch matrix readings.]]
 

= DMD Display Panel Repair =

The major DMD panel manufacturers were/are Vishay/Dale, Cherry, and Babcock. All three manufacturers used very similar designs that involved row and column high voltage signal routers as well as a few smaller discrete components. Some panels use 4 column drive ICs. Others used a larger degree of integration needing only 2 column drive ICs.

DMD panel repair is not always economically feasible, and generally requires a high level of soldering/desoldering skill. "Outgassed" displays aren't worth repairing as the glass panels are now difficult to find and pricey when they can be found. And, only the older display glass examples have "header pins" versus the "glue" or "tape" attachments to the board which simply aren't repairable.

However, there are a few situations where repair might be considered.

'''Shorted Negative High Voltages''' 

Under load, the negative high voltage pins should exhibit a 12VDC offset. If these voltages measure close to the same value when connected to the power supply, and the power supply tests good without the display connected, then it's likely that parts on the display panel are shorted.

When disconnected from power, measuring the resistance between the two negative high voltage pins should read about 330 Kohms. Shorted parts will cause this resistance to measure much less, perhaps even a dead short.

The ICs on the board can be tested via diode test. In the example below, it was easily determined that the 14069 at U6 was shorted. Also, pins 25 and 26 (in pics 2 and 4 below, the left side of the chip pad, 2nd/3rd and 4th pins up from the bottom) of the HV5222PJ at U8 where shorted. Damage to the two ICs was evident even with the naked eye.

<center>
<gallery widths=200px perrow=4 caption="Vishay/Dale DMD Panel Gallery">
File:DMDPanelFriedIC.jpg|<center>A fried 14069 on a shorted damaged DMD panel.</center>
File:DMDPanelFriedHV5222.jpg|<center>A shorted HV5222PJ row controller.</center>
File:DMDPanelU6Pads.jpg|<center>The solder pads for U6</center>
File:DMDPanelU8Pads.jpg|<center>The solder pads for U8</center>
</gallery>
</center>
 

=Testing an integrated circuit=
Besides using a logic probe to test integrated circuits when the game is turned on, there is another "game off" technique that can be used.

[[File:YT.png]] A video showing this procedure can be found [https://youtu.be/pGRAwfcy3kQ here].

This procedure works for many 74XX series ICs.

[[Image:ICTesting.jpg|200px|thumb|right|Testing ICs with a DMM]]
'''Procedure''':
#Remove as many connectors as possible from the board being tested. The less components connected in circuit, the more accurate test.
#Digital Multi-Meter (DMM) set to "diode test".
#Place the red lead on the ICs ground leg. With pin 1 of the IC oriented up and left, ground will most times be the pin on the lower left side of the IC. That is, for a 14 pin IC, ground is generally pin 7. For a 16 pin IC, ground is generally pin 8. And so on... Likewise, the red lead can be connected to the general ground plane of the board. This is beneficial if testing multiple chips on the same board.
#Place the black lead on each of the other legs of the IC one at a time.
 

'''Interpreting the results:'''
*A reading between .4 and .7 generally means the leg, and the internal gates associated with it, are OK. 
*A reading of "short" indicates a definite problem with the chip UNLESS, that leg is tied to ground. Consult the board schematics. 
*A reading of "open" indicates a definite problem with the chip. 
*Disregard readings when the black lead is connected to either the +5v logic bus or ground.
*Comparing your results against results from a known good IC (of the same kind) is a good practice.
 

Readings outside of this range may indicate a failed IC, or may indicate that associated circuitry is pulling the reading one way or the other. If you remove the IC from the board, you can test the IC in complete isolation. In this case, the test is nearly 100% reliable.
 

Like transistor testing, this test can tell you that a part has definitely failed. However, since this test is not conducted "under load", the part may test good, but fail under normal load.
 

=Testing fuses=

[[File:BuzzingAFuseTheWrongWay.jpg|200px|thumb|left|An example of why you MUST remove a fuse to "buzz" it. This '''empty''' fuse holder is for the GI circuit in a Williams game. The meter is showing continuity with no fuse present. The meter is finding a path back through the transformer secondary.]] 
Fuses are used in many game circuits to protect failure of the circuit (shorts for instance) and possible subsequent drawing of too much power through the circuit. The fuse is specified at a particular rating so that it will be the "weakest link" in the circuit. In the event of a failure, the fuse "blows" to protect the rest of the circuit.

One of the basic tests to perform on pinball machines is to test fuses. A visual inspection of a fuse is not usually enough to reveal a potentially bad fuse, so a multimeter must be used to check for continuity across the fuse. To test the fuse, set the multimeter to the "continuity" or "buzz" setting.

Testing fuses while still in their fuse holder can provide a false positive reading, as shown in the picture at left. This happens (sometimes) as your DMM finds a path from one end of the fuse, through other game circuitry, and back to the other end of the fuse. To prevent false positives, always remove the fuse from it's holder to "buzz" it out. At the very least, raise one end of the fuse out of the holder.

This is also a good time to ensure that the correctly rated fuse is in place. Compare the spec for the fuse (contained in your game manual or on a backbox sticker) to the actual fuse. Amperage, voltage, and fast/slow blow ratings should be checked. Never use a higher '''amperage''' fuse than specified. Always use a fuse rated at least as high as the spec '''voltage''' (higher is OK), and always use the correct '''fast/slow blow''' type. If you use a higher amperage rated fuse or a slow blow instead of a fast blow, you risk alleviating the fuse of it's job of being the "weakest link", and instead, your game will find the next "weakest link", possibly a printed circuit board trace or other game wiring.

Lastly, tarnished fuse holders or fuse ends, increase resistance, adversely impacting your game's power circuits. If you need to replace a fuse holder, ensure that the new holder is rated sufficiently for the application.
 

=Testing for Shorted Signals=
[[Image:SolderBridge.png ‎|300px|thumb|right|A very tiny solder bridge appearing on a Bally -35 MPU at U5. This bridge shorted A0 and D7 together, preventing the board from booting.]] 
Solder splashes and craptastic prior rework are the bane of pinball board techs across the globe. Sometimes, high voltage shorts to a board will cause internal chip shorts, bridging two signals within the chip. Whatever the reason, signals shorted together can be difficult to track down.

A methodical process for detecting signals shorted together follows.

#Set a DMM to continuity.
#Black probe on pin 1 of the microprocessor (chosen since almost all signals go to the microprocessor. Other ICs might be a better choice given the problem being diagnosed)
#Starting with pin 2 of the microprocessor, use the red probe to "rake" pins 2 through 40.
#In general, there should be no continuity. If continuity is detected, consult the schematics for possible signals tied to ground or to 5VDC. At this point, signals shorted together may have been identified.
#Move the black probe to pin 2 of the microprocessor.
#Rake pins 3 through 40, listening for continuity.
#Move the black probe to pin 3 of the microprocessor.
#Rake pins 4 through 40, listening for continuity.
#Continue the process until all pin-to-pin tests have been completed (black probe on pin 39, "raking" pin 40 with the red probe).

[[File:YT.png]] A video showing this procedure can be found [https://youtu.be/iER9xUZcwDs here].
 

=Testing a Diode=
[[File:TestingADiode.jpg|200px|thumb|left|Testing a diode. This diode measures fine in this direction.]] 
A modern solid state pinball machine uses hundreds of diodes in the switch matrix, lamp matrix, and on coils.

Diode in a switch or lamp matrix are used to electrically isolate the switch or lamp within the matrix. This allows the MPU to sense only the switches it intends to, and turn on only the lamps that it intends to.

Diodes are used on coils to "snub" the "back electromotive force" or back EMF. Without this snubber diode, the reverse current created when the coil's magnetic field collapses would damage the transistor that allows power to the coil to flow to ground and turn on the coil.

Diodes on coils (or in coil circuits) can not be tested in circuit. This is because electricity always follows the path of least resistance. Your DMM will measure the current drop through the coil winding instead of the diode itself. At least one leg of a diode must be cut from the coil to test the diode. Since diodes are so cheap, it's reasonable to simply replace a suspect coil diode.

Diodes on lamps and switches may be tested in circuit. 

Testing a diode:
#Set your meter to diode test
#Black lead on the "banded side" of the diode
#Red lead on the "non-banded side" of the diode
#A reading of .4 to .7 should be measured
#Reverse the leads
#An open reading should be measured (not short, or zero resistance)

1N4004 diodes are typically used for pinball applications although anything from a 1N4001 to a 1N4007 can be used for switch, lamp, and coil applications. 1N4148 and 1N5817 diodes are also used. They can be tested in the same way as shown above but the anticipated reading will vary.

Zener diodes can also be partially tested using the same technique. Zener diodes "break down" at a specific voltage, which is less than the voltage that a DMM uses in diode test. While it's possible to test the diode's ability to block voltage, verifying it's breakdown voltage is not possible with DMM alone.
 

=How coils, flashers, and motors are turned on=
In this section, we'll use a coil for the example. The principle is identical for all other solid state driven devices, such as flash lamps and motors.

In most machines, every coil will have power "waiting at the ready" at all coil lugs. Exceptions are... 
*Williams System 11 and Data East/Sega games which have an A/C (side) select relay that switches power between two banks...a bank of coils and a bank of flashers.
*Flipper coils on Data East games that use the Solid State Flipper Board. The SSFB provides power to the coils only after the cabinet flipper button switch is closed.

[[File:CoilPowerDiagram.jpg|400px|left|thumb|A simple representation of how power is always present at all coil lugs, waiting to "find ground" via a switch. Solid state pinball machines use transistors to "switch" power to ground (a TIP-102 transistor for instance)]] 
If you set your DMM to DC voltage, place the black lead of your DMM on game ground such as the ground braid or the side rail, and place the red lead of your DMM on either coil lug, you should read nominal coil voltage (exactly what voltage level depends on the game system). Your DMM reads the voltage at both/all coil lugs because, when the coil is off, there is no current through the coil to cause a voltage drop. Power present at one coil lug is guaranteed to be present at the other coil lug unless the coil winding has a break in it or the winding is disconnected from the lug.

Referencing the diagram at left, placing the red probe of your DMM at any point labeled "P", and the black lead of your DMM on game ground (labeled "G"), should read nominal coil voltage.

All that is required for the coil to "fire" is for the ground lug of the coil to find a path to ground. This is accomplished by "turning on" a transistor, or by closing a switch that creates a path to ground.

This is also a good illustration of how to test a coil, and the power circuit. Grounding the coil lug attached to the non-banded side of the diode will cause the coil to fire if the circuit is working properly. If the coil does not fire, then either the coil is not receiving power, or the coil winding has a break in it, or the coil winding is not attached securely to the coil's solder tab(s).
 
=Testing a Bridge Rectifier=

==General Information About Bridge Rectifiers==

[[file:Bridge-rectifier-lugs.png|thumb|left|200px|A typical bridge rectifier.]] 
A bridge rectifier integrates 4 discrete diodes into a single package. The purpose of a bridge rectifier is to convert (or rectify) AC voltage into DC voltage.

An example of a bridge rectifier is pictured at left. Bridges will have either "spade" leads (as used on Williams System 11 and Data East power supplies) or wire leads (as used on WPC Power/Driver boards). Both types operate in exactly the same manner.

Note the notch in one corner of the bridge rectifier. On older bridge rectifiers, there may be a small bump on the corner instead of a notch. In either case, this feature indicates the (positive) DC output. Diagonally opposite that lug is the (negative) DC return.
 

[[file:Bridge-rectifier-schematic.jpg|thumb|left|300px|A bridge rectifier schematic showing the four internal diodes]] 
When testing a bridge rectifier, it is actually the individual internal diodes that are being tested. Be sure to review "[[#Testing_a_Diode|Testing A Diode]]" for the simple test procedure.
 

[[File:Bridge-rectifier-made-with-diodes.jpg|thumb|left|300px|Making a bridge rectifier out of diodes]] 
To help illustrate how a bridge rectifier is arranged, here is how one can be assembled using diodes.
 

[[file:Ac-dc43.jpg|left|300px|thumb|Comparison of Electrical Waveforms]] 
What a bridge rectifier actually does is alter the waveform of electrical voltage. Alternating Current (AC) has a waveform that alternates (rises and falls at a generally consistent frequency, or "cycles", hence terms like 60 cycle power as is found in the US). Typically, the cycle resembles a [https://en.wikipedia.org/wiki/Sine_wave sine wave]. The time measured between each peak of the wave represents a single cycle (or "hertz", abbreviated as "Hz"). In the United States, AC power is 60Hz, while in Europe, it is 50Hz.

A full wave rectifier "flips" the negative portion of the sine wave into a positive wave. A half-wave rectifier simply eliminates the negative portion of the sine wave.

In power circuits that need a consistent voltage with little remaining AC component or "ripple", a large value "filter" capacitor is used to attenuate the AC ripple out of the waves and produce a steady, "flat" DC (Direct Current) voltage. The capacitor charges as the AC signal rises and then discharges as the AC signal falls, keeping the output voltage more or less constant DC. This technique is used in the 5VDC power circuits of most game systems. 

==Bridge Rectifier Testing Procedure==
The procedure and pictures below illustrate how to test a bridge rectifier with a DMM.

[[File:YT.png]] A short video demonstrating the following procedure can be found [https://youtu.be/rt9HZtuNenk here].

'''Procedure:'''
#Place your DMM into "diode test".
#Put the black lead of your DMM on the "oddball" lead of the bridge rectifier. This will be the lead that isn't oriented the same as the others (as with the "spade" type of bridge) or the lead that prevents the four legs from forming a square (as with the "wire lead" type of bridge). This will also be the DC positive lead of the bridge.
#Place the red lead of the DMM on each of the adjacent legs, one at a time.
#A reading nominally between .5 and .7 should be seen (this represents the voltage drop across the bridge's internal diodes).
#Now place the red lead of the DMM on the lead opposite of the "oddball" lead, or the DC negative lead of the bridge
#Place the black lead of the DMM on each of the adjacent legs, one at a time.
#Again, a nominal reading between .5 and .7 should be seen.
 

<center>
<gallery widths=400px heights=400px perrow=2 caption="Four steps to Test a Bridge Rectifier. Black/Red dots represent test lead positions.">
File:TestingABridgeRectifierFourSteps.jpg|<center>"Wire" style bridge as found on WPC Power/Driver and FlipTronics II boards.</center>
File:SpadeStyleBR.jpg|<center>"Spade" style bridge as found on Data East and WMS Power System 11 Power Supplies and Data East PPB boards.</center>
</gallery>
</center>
 

[[File:TestingBridgeRectifier.jpg|300px|thumb|left|Testing a Bridge Rectifier in circuit. This part of the bridge is good.]] 
Readings outside of these ranges indicate a failed or failing bridge. Note that these readings are not "hard and fast". For instance, a reading of .462 is probably acceptable. We are looking for an "open" or a "short". Note also that this test is not conducted "under load" and it is possible for the bridge to test "good" when it will in fact fail under load (this is also true when testing diodes, transistors, etc).
 

=Testing a Transistor, Silicon Controlled Rectifier (SCR) or Field Effect Transistor (FET)=

<need to validate correctness...I'm making some assumptions here...> 
<MJE15030/31 readings probably not correct for left leg...should be about 1.1> 
<need to add a separate section on FETs> 
<need to add a separate section on SCRs> 

A transistor is a device for amplifying current. A small current flowing from the base to the emitter causes a large current to flow from the collector to the emitter. It is a bit like a relay, where the base-emitter circuit is the coil, and the collector-emitter circuit is the switch contact. Transistors come in two polarities, NPN and PNP. NPN transistors are the most common, because they work towards ground. PNP transistors work towards positive, and are rarely used except for the power side of the switch matrix, and some voltage regulators.

A transistor can fail in two ways. When the interior material melts and fuses, it creates a continuous short. More rarely, the transistor may fail "open", and never switch the circuit.

Transistors are distinguished from FETs and SCRs (testing these components to be added later)

[[Image:TransistorSymbols.jpg]]

Transistors are also manufactured in several "package" types or form factors. Some common package types used in pinball machines are:
*TO-3, such as a 2N3055, 2N6057, MJ2955, MJ10000. Viewing component from the back side, oriented so that the legs are closest to the bottom, the case is the Collector, Emitter on the left, Base on the Right
*TO-39, such as a 2N3440 as found on Bally/Stern Regulator/Solenoid Driver boards
*TO-66, such as a 2N3584 as found on Bally/Stern Regulator/Solenoid Driver boards
*TO-92, such as a 2N4401, 2N5401, MPS-A13. Legs arranged EBC
*TO-218, such as a TIP-36c as found on Williams WPC Power/Driver boards. Legs arranged BCE
*TO-220, such as a TIP-102, TIP-107 as found on Williams WPC Power/Driver boards and MJE15030/MJE15031 found on many power supply boards. Legs arranged BCE (left to right)

Every transistor has an emitter, a base, and a collector, commonly referred to as EBC.

Exactly how a transistor is tested depends on the package type, NPN vs PNP, and leg layout. 
'''All testing begins with your DMM set to "diode test"'''. 
Note: some DMMs will show 4xx - 6xx (versus .4 to .6 as noted below). 
'''Note: A transistor can "test" good and still be bad!!''' 

[[File:TO-3.jpg|thumb|300px|right|Pinout of TO-3 Transistors. Note Emitter, Base, Collector.]] 

'''NPN TO-3''' MJ10000 
Black Probe-Red Probe
#E-B .250
#E-C open
#B-E .250
#B-C open
#C-E .530
#C-B .530

'''NPN TO-3''' 2N3055 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn

'''NPN TO-3''' 2N6057 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn

'''NPN TO-3''' 2N6059 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn
 

'''PNP TO-3''' MJ2955 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn
'''PNP TO-3''' 2N5875 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn

'''PNP TO-3''' 2N5879 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn

'''PNP TO-3''' 2N5880 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn

'''PNP TO-3''' 2N5884 
Black Probe-Red Probe
#E-B nn
#E-C nn
#B-E nn
#B-C nn
#C-E nn
#C-B nn
 

'''NPN TO-92''' package (2N3904, 2N4401, 2N5550, 2N5551, 2N6427, MPS-A13, MPS-A42, PN2222A)
#Place the '''red''' lead of your DMM on the center leg of the transistor
#Probe each of the flanking legs with the '''black''' lead
#.4 to .6 volts is a normal reading
#Readings outside of this range indicate a failed transistor

'''PNP TO-92''' package (2N3906, 2N4403, 2N5401, MPS-A92)
#Place the '''black''' lead of your DMM on the center leg of the transistor
#Probe each of the flanking legs with the '''red''' lead
#.4 to .6 volts is a normal reading
#Readings outside of this range indicate a failed transistor

'''NPN TO-220''' package (TIP-31C, TIP-32C, TIP-41C, TIP-102, TIP-122, MJE15030, 2N6043)
#Place the '''black''' lead of your DMM on the metal tab of the transistor
#Probe each of the flanking legs with the '''red''' lead
#.4 to .6 volts is a normal reading. Readings outside of this range indicate a failed transistor
#Probe the center leg with the red lead
#A "short" should be seen. If not, then the transistor has failed.

'''PNP TO-218 and TO-220''' package (TIP-36C, TIP-42/A/B/C, TIP-107, MJE15031)
#Place the '''red''' lead of your DMM on the metal tab of the transistor
#Probe each of the flanking legs with the '''black''' lead
#.4 to .6 volts is a normal reading. Readings outside of this range indicate a failed transistor
#Probe the center leg with the black lead
#A "short" should be seen. If not, then the transistor has failed.

Testing an '''MPS-A13''' transistor.
#Place the '''red''' lead of your DMM on the center leg
#Place the '''black''' probe on left leg (viewing the component side of the board). That leg should read about 1.3
#Move the '''black''' probe to the right leg. That leg should read about .7
#Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

Testing an '''MPS-U45''' transistor (or '''NDS-U45''' or '''CEN-U45''' which are equivalents).
#Measure on the solder side of the board, with J5 and J6 oriented toward you
#Place the '''red''' lead of your DMM on the center leg
#Place the '''black''' probe on left leg. That leg should read about 1.3
#Move the '''black''' probe to the right leg. That leg should read about .7
#Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.

==Testing a FET==
[[File:YT.png]] A video showing how to test a FET can be found [https://youtu.be/swW4rUB_aAc here]
 

=Testing a coil=

[[File:BurntCoil1.jpg|200px|thumb|left|Melted coil sleeve and bobbin. Ouch!]] 
If a drive transistor shorts, providing an unintended path to ground for power at a solenoid, it will cause the associated solenoid to activate at full power and stay activated. If the coil winding gets hot enough, it will burn through the protective coating on the winding, shorting adjacently wound wires and reducing the resistance to near 0 Ohms. If this happens and you replace the failed driver transistor, but you don't check the coil, the shorted coil will cause the transistor you just replaced to be damaged immediately after power on.

If you are unsure of the condition of the coils in a machine it is wise to check each coil's resistance '''*before*''' switching the machine on. The human nose can be a very useful tool in diagnosing when something has burned, so use it! Even examining each coil in the game for burned coil wrappers may help identify a shorted coil. Another good method of examination is to ensure that the plunger can smoothly slide into the coil sleeve. If the coil sleeve and/or bobbin are melted, you know immediately.

Some flipper coils are "two coils in one," where they have a power winding and a hold winding. These are easily identified as they have three lugs instead of two. You can treat these as two "separate" coils for the purposes of the tests below.
 

==Testing resistance==
To test a coil's resistance:
* set your DMM to 'Ohms' and attach your red and black probes to the coil lugs.
* If the coil measures less than 2 Ohms, the coil has either shorted internally or there is a wiring fault. Note: Some flipper coils will read less than 2 ohms but still be fine.
* Desolder the wires going to the coil lugs and check the resistance across the coil lugs again. If it reads the same value when disconnected, then the problem lies with the melted coil. If the coil resistance reads 'normal' when it is disconnected (i.e. the coil is 'ok'), you may have a wiring or drive transistor issue.

It is wise to check all wiring and transistors associated with a melted coil before powering the game on again.

==Testing for coil power==
With the machine powered on:
* set your DMM to DC
* Attach the black lead to a grounding strap
* Touch the red lead to coil lug closest to the banded side of the coil diode (if it has one).
* Depending on the coil and game, you should see a reading of 20V - 75V.
* Now touch the red lead to the other coil lug.
* Again, you should read 20V - 75V. If not, then the coil winding is severed somewhere between the two lugs. Most of the time, the wire breaks where it is soldered to the coil lug.

Please note that some games incorporate a coin door interlock "safety" switch that must be closed to power the solenoids.

==Testing the coil diode==
If the coil wires are connected backwards on a coil that should have a diode (i.e. WMS System 11), the coil diode will blow instantly when powered on. If you fit a coil that is supposed to have a coil diode and it doesn't (or the diode has shorted), you'll probably blow the drive transistor. This can lead to a vicious cycle of replacing coil diodes and drive transistors.

To test a coil diode:

* Cut one of the legs and bend it up so it's disconnected on one side. Be careful not to cut the coil wire or lug.
* Set your DMM to 'Diode' mode.
* Place the black lead on the banded side.
* Place the red lead on the non-banded side. You should see a reading of 0.5 or thereabouts.
* Carefully solder the leg 'back together.'

The reason that one leg of the diode must be cut is that your meter will read the path of least resistance, which will be the coil winding if the diode was still connected.

==Testing the driver transistors==
In your game manual you will (normally) find a list of which transistors is associated with each coil. If you have checked the wiring back to the driver board and the coil itself, then it's time to start testing the driver transistors. See "Testing a transistor" [[General#Testing_a_Transistor.2C_Silicon_Controlled_Rectifier_.28SCR.29_or_Field_Effect_Transistor_.28FET.29| here]] for more details.

=Basic Sound Troubleshooting=
Regardless of the manufacturer, there are some simple steps to follow if no sound is present. Below are the steps from simplest to more complicated.

# Make sure the speaker is properly connected. If female crimp spade connectors are used on the wiring connecting to the speaker terminals, it is not uncommon for the connectors to come loose or even break. If the leads to the speakers are soldered onto the speaker terminals, make certain the wires are soldered well by gently tugging on the wires. 
# Make sure the speaker is good. If no sound is coming out of the speaker, not even a hum when the volume pot is turned up, check to see if the speaker is not blown. For what it is worth, even a speaker with a ripped cone can put out some sound in most cases. The sound may be distorted, but it should be present. There are two ways to test a speaker. The safest way is to hook an ohmmeter up to the two speaker leads, and see if the resistance equals the impedance of the speaker. Most, if not all speakers in pinball machines are either 4 ohm or 8 ohm. The other method for testing a speaker is to hook a 9v battery up to the speaker leads. Prior to hooking up a battery, it is important to disconnect the speaker outputs on the sound board. This will isolate the speaker from the sound board completely. Once the battery is hooked up, the speaker cone should either pull in or flex out, depending on how the battery's polarity was connected to the speaker. '''Do not allow the battery to be connected to the speaker for very long'''. 
# Make sure the volume potentiometer (pot) is properly connected, if one is used (newer machines like WMS WPC, Stern / Sega White Star, and stern SAM systems use digital potentiometers). If turning the volume pot up does not result in any sound, turn the pot the opposite direction. If no mechanical pot is used, skip the next step. 
# Make sure the volume pot is good. Using an ohmmeter. connect the leads to the volume pot, and turn the pot back in forth. When the pot is turned completely one way, it should read close to zero ohms (full volume). When turned the opposite direction, the reading should be close to the value of what the pot's rating (pots in pinball machines roughly range from 5 kohms to 25 kohms depending on the manufacturer). Pots sometime develop "dead spots". When the pot is turned from its lowest setting (highest resistance value) to its highest setting (0 ohm resistance), the resistance value should slowly decrease. While turning the pot, if the value spikes to 0 and resumes to a higher value than 0, the pot has a dead spot. TV tuner cleaner can be used to sometimes rectify this problem. Even exercising the pot back and forth can resolve dead spots in a pinch. 
# Make sure the output connections on the sound board are good. If the sound board in question has header pins on the output to the speaker / volume pot, check for cracked header joints. Short of a visual inspection with the board removed from the game, try wiggling the output connector. This does not definitely prove that there are cracked header joints, but it shows that either the headers or the harness connector is at fault. Additionally, check for bad connectors inside the speaker output housing connection. If the sound board in question uses edge finger connections, check the edge connector inside the housing of the output to the speaker. In either case, if the output harness uses an insulation displacement connector (IDC), check to make sure the wires are securely seated inside the connector of the housing. 
#In some but not all instances, sound boards use a 5-legged amplifier with a heat sink attached. Sound boards with this type of amp may have cracked solder joints at the legs of the amp. If gently wiggling the amps heat sink makes sound cut in and out, suspect cracked solder joints on the legs of the amp. 

Remaining issues are typically sound board specific. Please review the appropriate repair pages regarding the sound board in question.
 

=Replacing obsolete/hard to find parts=
Need to cover... 
resistor/capacitor networks (SRCs) 
SOIC to DIP adapters 

* Blocking Diodes: Blocking diodes that are rates at a higher voltage can be used to replace blocking diodes rated for a lower voltage.
* Transistors: Transistors that are rated for higher amperage and/or voltage can usually replace lower rated transistors, so long as the polarity and package are the same. In certain situations, MOSFETs can sometimes be substituted for transistors.
* Resistors: Resistors with a higher wattage can be used to replace resistors with a lower wattage, so long as the ohm resistance rating is the same. Resistors with a tighter tolerance can usually replace resistors with a looser tolerance (ie, a component with a 1% tolerance can replace a component with a 5% tolerance).
* Capacitors: Capacitors that are used to filter voltages can usually be replaced with slightly higher capacitance (Farads). Capacitors used in timing circuits cannot generally be replaced with capacitors with a different capacitance without affecting clock/timing signals. Capacitors can usually be replaced with ones that have a higher voltage rating.

==Resistor Networks==
Resistor networks were used on many pinball PCBs to both ease the manufacturing process as well as to conserve printed circuit board space. Williams System 11 MPUs have several in the "battery corrosion zone" which sometimes need to be replaced.

Resistor networks come in two styles, bussed and isolated. Isolated resistor networks will have an even number of pins. Each 2-pin pair provides the resistor value. Typically, every other pin is tied to ground. Bussed resistor networks are similar, but each resistor shares pin 1 in common. All other pins provide the resistor value. In this sense, pin 1 (usually tied to ground) is "bussed". Bussed resistor networks may be of any length; both odd and even.

<center>
<gallery widths=220px heights=100px perrow=2 caption="Resistor Network Representations">
File:BussedResistorNetwork.jpg|<center>Bussed Resistor Network</center>
File:IsolatedResistorNetwork.jpg|<center>Isolated Resistor Network</center>
</gallery>
</center>
 
[[Image:ResistorNetworks.jpg|300px|thumb|left|A fabricated "isolated" resistor network on a Williams Hyperball driver board]] 
Should you be unable to acquire the correct value of resistor network, you can fabricate your own.

Isolated networks are easiest to fabricate as a discrete resistor may be substituted as shown in this picture. In the picture, SR16, SR2, and SR3 on a Hyperball driver board are replaced by discrete resistors. 

[[Image:BussedResistorSubstitute.jpg|300px|thumb|left|A fabricated "bussed" resistor network. Image courtesy of Alexander Visotin.]] 
Bussed networks may be fabricated in much the same way, with a resistor soldered in each position (except pin 1). All of the other ends of the resistors are then soldered to pin 1 as shown at left.
 

=The Switch Matrix=
All solid state pinball machines implement a "switch matrix." The switch matrix is comprised of "strobe lines" (generally 8) and "return lines" (also generally 8). At the intersection of each strobe and return line, an isolation diode in series with the actual switch, connects the strobe line to the return line.

The reason for implementing a switch matrix is easily understood: economy of wiring. To sense 64 switches, a total of 16 wires are required using a switch matrix. If the designers had chosen to sense those same 64 switches individually, a minimum of 65 wires would be required.

'''How a switch matrix works'''

Conceptually, operation of the switch matrix is pretty simple. The CPU commands the return circuitry to "listen" for a pulse on each row simultaneously. The CPU then commands a strobe at column 1. Any switch that is closed on column 1 will cause the signal to be propagated down the row return where the CPU will "hear" it. A return on row 1 after pulsing column 1 means that the switch at position 1,1 in the switch matrix is closed. The CPU then moves on to column 2 and repeats the same steps. After all 8 columns are strobed, the CPU then returns to column 1 and begins the whole process again. This continues as long as the game is powered on.

Note that the actual electrical circuit implementation is quite a bit more complex than this conceptual description and may be found in the particular manufacturer's section of the Wiki. Also note that a "pulse" in this context might not be a "high" signal but instead a "change in state" (from logic 1 to logic 0 or vice versa).

A representation of the Bally/Williams WPC switch matrix is shown in the picture below. The column strobes are represented by the vertical lines. The row returns are represented by the horizontal lines. 

<center>[[File:Wpc sw matrix.png]]</center>
 

'''Switch Matrix Problem Resolution'''

The first step is to determine whether the problem is within the MPU switch matrix circuitry, or off board, in the game wiring, switches, connectors, or diodes. Individual game system switch matrix sections should help with this determination.

Once you've determined that the problem is not on the game MPU, the possibilities are few and limited. Start be testing more switches than just the suspect switch. You'll need to determine if the problem is a single switch, multiple switches in a row/column, or all switches in a row/column.

'''Failed single switch''' 
If a single switch is not registering, examine the switch closely. Check that...
#The switch matrix row and column wires are securely connected along with the switch diode.
#The switch contacts are not fouled. Solid state switches should never be filed. However, not knowing the entire history of the game, there is a possibility that the switch may have been filed in the past. Ensure that the switch contacts "make" consistently.
#Test the switch diode isn't open. Use the normal diode check function on your DMM. The procedure is outlined in this section. If the diode is "open", the switch will never register.
#The switch matrix wiring hasn't been cut/broken. "Buzz" the connection from the switches column solder lug to another switch in the same column. Do the same for the switches row solder lug. If the switch matrix column or row "daisy chain" is broken, at least one switch will be inoperative. The odds are, that more than one switch will be inoperative since the break in the wiring can be anywhere in the (nominally) 8 switch row or column. However, a broken matrix wire could certainly render a single switch inoperative.

'''Multiple switches in a row or column inoperative, but not ALL switches in the row or column''' 
If more than one switch in a row or column is inoperative, it's certain that the switch matrix column or row "daisy chain" has been broken. Again, use your DMM, set to continuity, to "buzz" the connection between switches on the same row/column, to ensure that the wiring hasn't been cut/broken.

'''All switches in a row or column are inoperative''' 
If all switches in a row or column are inoperative, this may be a special case of the prior example. Or, the problem may be within the MPU's switch matrix circuitry (which is covered in individual game model sections). Use the same technique of "buzzing" for continuity to ensure that the row and/or column wiring hasn't been broken. Buzz from the switches row/column solder lug to the connector at the MPU and then onto the MPU to ensure that the connection is reliable. Broken wires at an IDC connector are common. Fractured solder joints on the male headers are somewhat less common, but still possible.

'''"Ghost" switches being reported simultaneous with other switch closures''' 
"Ghost" switch closures not associated with failed MPU circuitry are sometimes difficult to track down. These are caused by a shorted isolation diode (on a closed switch), incorrect wiring at the switch, or switch lugs or diode leads being shorted together. For a "ghost" switch to be reported, one of the aforementioned conditions must be met AND at least two other switches must be closed. An excellent description of what happens with a shorted isolation diode and how to troubleshoot the issue can be found [https://www.youtube.com/watch?v=ZgSyTmyZAxM here].

'''Maladjusted switch retention blade causes switch short'''
[[File:ShortedSwitchDueToStay.jpg|200px|thumb|left|A switch blade retention "stay" causing a switch short. Image contributed and edited by PinSiders bax1 and quench.]] 
Some (most) switch blade pairs are physically kept open with a retention blade, also referred to as a switch blade tensioner. The purpose of this extra blade is minimize switch "bounce". Switch stacks were manufactured with the retention blade adjacent to the short / stationary switch blade, and it is electrically shorted to that blade. If the retention blade is not adjusted correctly, and is touching the longer switch blade, the switch will be reported as closed even though the switch pair contacts are not touching.
 

==Diode and Switch Matrix Wiring Orientation on a Microswitch==
[[File:Submicro Switch Wiing.jpg|300px|left|thumb|Typical wiring for any Microswitch]]
First and foremost, all switches located in the switch matrix MUST have a diode. Secondly, the diode has to be installed in the correct orientation. If a diode is installed "backwards", the end result my be that all of the switches in that particular row get triggered or even stranger issues occur. Finally, the diode legs must not be connected to any of the other wires or terminals of the switch, or the switch will funk up the switch matrix.

Here is the correct orientation for the wiring and the diode on a microswitch. The white wire w/ trace and non-banded side of diode is connected to NC terminal. The banded side of diode is connected to common terminal. Finally, the green wire w/ trace is connected to NO terminal.
 

=Switch Matrix In Action=

[[Image:Normal_switch_matrix_operation.jpg|200px|thumb|left|Normal Switch Matrix Operation]] 
https://www.youtube.com/watch?v=Bo3wVuyJtXA 
[[Image:Shorted_diode_in_sw_matrix.jpg|200px|thumb|left|Implications of a Shorted Diode in the Switch Matrix]] 
https://www.youtube.com/watch?v=rNx2D6KeAxQ
 

=General Illumination=

General Illumination is lighting that switches on (generally) when game power is turned on. Some general illumination circuits are switched on by an electromechanical relay (EM games, Williams System 11, and all eras of solid state Gottlieb games for instance). Some GI circuits are controlled by the MPU (WPC games). General illumination lamps are essentially the same as Christmas tree lights. They come on when power is applied.

[[File:SST-GIModification.jpg|200px|thumb|left|Underside of Starship Troopers playfield showing mod to top lane guide GI lamp installation.]] 
Some GI sockets are very difficult to get to, like in Sega's Starship Troopers. One way to ease the job is to get at the lamps from under the playfield where possible. This requires a small modification to your game and some short wood screws. In the picture at left, the OEM staples have been removed and replaced with a standard pinball target screw. One screw is really enough since the lamp isn't going anywhere. To replace a lamp, simply remove the screw, pull the socket, replace the lamp, and reinstall. Make certain the length of the screw will not protrude through the top of the playfield. Those who prefer the look of LEDs should consider using LEDs in these tough to reach places. 

=The Lamp Matrix=

Many (if not most) pinball makers used a lamp matrix to drive the game's controlled lamps. Manufacturers that used a lamp matrix include Williams, Data East, Sega, modern Stern games, and Gottlieb System 3 games (which multiplex the switch/lamp matrix). Classic Bally/Stern games, Atari, and Gottlieb System 1 and System 80 games drive the controlled lamps with individual transistors (or silicon controlled rectifiers).

All EM's control lamps with relay controlled switches, or wipers on disc units.

'''How the lamp matrix works'''

A lamp matrix consists of (typically) 8 column drives and (typically) 8 row returns. At each of the 64 (8x8) intersections of this 8-by-8 matrix, an isolation diode and a lamp in series, connect the column to the row. To light a particular lamp in a row, the processor sets up the row circuitry to create a path to ground for that row. The processor then "strobes" the column containing that lamp with a short pulse of "controlled lamp" power. Since the row has been set up to create a path to ground, the lamp illuminates.

The processor can light any or all lamps in a particular column simultaneously by setting up the row circuitry to create a path to ground for the desired lamps. When the column is "strobed", all of those lamps will light.

The processor will work it's way through the lamp matrix (column 1, column 2, ... column 8, repeat) continuously.

Note that the actual electrical circuit implementation is quite a bit more complex than this conceptual description and may be found in the particular manufacturer's section of the Wiki.

A schematic of the Bally/Williams WPC lamp matrix is shown in the picture below. WPC column strobes always use yellow wires. WPC row returns always use red wires. 

<center>[[File:TypicalLampMatrixWPC.jpg]]</center>
 

'''Advantages of the lamp matrix'''

#Fewer wires
#Sometimes easier to identify why a lamp is not lighting
#Can use PWM to extend lamp life. Pulse Width Modulation is the technique for varying the "dwell" time that a lamp power/ground connection is established. In this way, a lamp can appear to be solidly on when in fact, power is being pulsed to it rapidly.

'''Lamp Matrix Problem Resolution'''

The first step is to determine whether the problem is with the game PCB's (MPU and/or driver board) lamp matrix circuitry, or off board, in the game wiring, lamps, connectors, or diodes. Individual game system lamp matrix sections should help with this determination.

Once you've determined that the problem is not on the game MPU, the possibilities are few and limited. Start by examining more lamps than just the suspect lamp. You'll need to determine if the problem is a single lamp, multiple lamps in a row/column, or all lamps in a row/column.

'''Failed single lamp''' 
If a single lamp is not lighting, examine the lamp closely. Check that...
#The lamp matrix row and column wires are securely connected along with the lamp diode.
#The lamp socket is not corroded. Using a "cleaning stick" inside the socket works well. Some manufacturer's sockets were better than others. Early Bally solid state lamps sockets (although early Bally games didn't use a lamp matrix) were of very poor quality (don't mess with those...simply replace them).
#Test to ensure the lamp diode isn't open. Use the normal diode check function on your DMM. The procedure is outlined in this section. If the diode is "open", the lamp will never light.
#The lamp matrix wiring hasn't been cut/broken. "Buzz" the connection from the lamp's column solder lug to another lamp in the same column. Do the same for the lamp's row solder lug. If the lamp matrix column or row "daisy chain" is broken, at least one lamp will be inoperative. The odds are, that more than one lamp will be inoperative since the break in the wiring can be anywhere in the (nominally) 8 lamp row or column. However, a broken matrix wire could certainly render a single lamp inoperative.

'''Multiple lamps in a row or column inoperative, but not ALL lamps in the row or column''' 
If more than one lamp in a row or column is inoperative, it's certain that the lamp matrix column or row "daisy chain" has been broken. Again, use your DMM, set to continuity, to "buzz" the connection between lamps on the same row/column, to ensure that the wiring hasn't been cut/broken.

'''All lamps in a row or column are inoperative''' 
If all lamps in a row or column are inoperative, this may be a special case of the prior example. Or, the problem may be within the MPU's (or driver board's) lamp matrix circuitry (which is covered in individual game model sections). Use the same technique of "buzzing" for continuity to ensure that the row and/or column wiring hasn't been broken. Buzz from the lamps row/column solder lug to the connector at the MPU (or driver board) and then onto the MPU (or driver board) to ensure that the connection is reliable. Broken wires at an IDC connector are common. Fractured solder joints on the male headers are somewhat less common, but still possible. It is also possible on lamp matrices that use PWM for a locked on column to blow all the lamps in the column.

'''"Ghost" lamps lighting simultaneous with other lamp lighting''' 
"Ghost" lamp illuminations such as a lamp in column 1 lighting at the same time as a lamp in column 2 on the same row, are almost always due to a shorted lamp matrix transistor providing power (or ground) continuously, and allowing adjacent matrix row or column lamps to light. Note that ghosting here does not refer to LED replacement lamps, which sometime light when they shouldn't in lamp matrix use that was not designed with LEDs in mind.

=Flippers=

;How does a flipper work?
:Flippers typically have two coil windings. One is a high powered, low resistance winding, used for the power stroke (initial "flip"). The other is used to keep the flipper held up, when you are holding the flipper to trap a ball. There needs to be a mechanism to switch from the high powered side to the low powered side. The high powered side of the coil is almost a dead short, and anything other than a momentary activation would cause the coil to overheat or the fuse to blow. Note that it takes less power to hold the flipper up than it does to pull the plunger in for the initial flip due to the effect the metal plunger has on what is initially an air-core coil.

;High Voltage flipper operation
:The original flipper operation was completely high voltage, requiring tungsten point contacts at the flipper switches and at the normally closed end of stroke switches. These switches need to be filed periodically and gapped correctly for proper operation. A maladjusted end of stroke switch can burn out a coil or a fuse as well as damage the plastic bobbin the coil is wrapped around, making for sluggish operation. Tarnished and burnt contacts at any point in the system can cause a weak flipper power stroke, making for diminished game play. Additionally, there are contacts on a machine's flipper relay that may need to be cleaned to provide the maximum power to the flippers. Connectors and header pins can also play a factor in a flipper's power; heavily tarnished connections will degrade performance.

:When you press a flipper button, you are actually grounding the flipper circuit, not providing the power. The power is already present at the coil's input lug. The power flows from the power supply to the flipper coil in the most direct path possible. The input lug has the solenoid power present: one wire going to one blade of the end of stroke switch, and one end of the hold winding; one end of the high powered coil's winding is attached to the other blade of the end of stroke switch.

:The flipper button has one contact attached to the terminus of both flipper coil windings; the other contact is attached to ground via the flipper relay. When the flipper relay is pulled in a ground path exists for the flipper. When it is deactivated (in game over/tilt modes) there is no ground path for the flippers. When you push the flipper button, the power travels through the end of stroke switch, the high powered coil, through the flipper cabinet switch, and the relay to ground, pulling the flipper in with great force.

:A small arm on the pivot point of the flipper presses against the end of stroke switch outer blade, moving it away from the inner blade. This cuts the high power to the stroke side of the coil. Because the hold coil still is getting power via the input lug, the flipper will stay in an up position as long as you hold the button in. The hold coil has much greater resistance and so does not blow the fuse or create a short circuit.

;Solid State Flipper operation
:Solid state flippers do not refer to flippers in any solid state machine; rather, they refer to a design in later machines (post 1989) to eliminate the traditional high powered tungsten contacted type of flipper, which was subject to degradation over time. Less maintenance is required for solid state flippers.

:There are a few different designs to eliminate the high power switches used with flippers. One circuit monitors the time the flipper is held in; anything over 50-100 milliseconds continuous activation switches the power to the low side of the coil from the upper side electronically. Some designs of this nature also have a low powered normally open end of stroke switch, so that the flipper feels more like a traditional flipper. The time function of the solid state circuit only comes into play if the end of stroke switch is never detected, switching the power to the hold coil. Williams Fliptronics(tm) flippers operate in this fashion.

:Another design monitors the end of stroke switch/time and pulses the power supply to the flipper to reduce the voltage during the hold cycle. This allows a cheaper coil to be used as there is only one winding on the coil. Examples of this type of PVM flipper are late model Stern games. Sometimes the pulsing of the voltage causes the flipper to buzz slightly.

;Summary of EOS switch function for various types of games
*EM: EOS switch shorts hold winding until flipper is actuated. This allows the power coil to provide full strength during the flipper movement but switch over to the lower power hold winding at the end of movement. In reality, both the power and hold coils are in series during hold operation.
*Data East: Flipper switch pulses power winding with a timed (40 ms) switch-over from 50V to 8V for hold operation. The EOS switch is only used to re-flip a knocked down flipper. See Maverick game manual page 90 for theory of operation.
*Stern: Flipper switch pulses power winding with a timed (40ms) switchover to 1ms pulses every 12ms to hold the coil up. The EOS switch is only used to re-flip a knocked down flipper. For a description of Stern flipper operation (from the SAM era), see [https://sternpinball.com/wp-content/uploads/2018/11/Batman_TDK_Manual.pdf Stern Batman TDK Manual Section 5 Chapter 2 Page 106]
*Williams: Fliptronic board provides CPU-controlled coil drivers for the flippers. When EOS switch closes power is switched to the hold winding. Williams WPC flipper problems are discussed in the [[Williams_WPC#Flipper_Problems]] section.

==Weak Flippers - What to check==
[[File:CoilSleeveWithInternalRingResized.jpg|200px|thumb|left|A worn coil sleeve, with an internal "ring" worn into it. This ring prevented the plunger from being fully pulled in.]] 
There are many problems that can lead to weak flippers. Some flipper problems are unique to EM games, but there are many problems common to both EM and SS games.
Problems can be either electrical or mechanical. Below is a list of items to check. General things to note are whether both flippers are weak or just one, if the flipper won't flip will it stay up if the bat is manually moved to the up position, and does the flipper bat move easily when moved by hand. The following list details problems that can cause weak flippers.

#End-of-Stroke (EOS) switch dirty. The power winding of a flipper coil is only a few ohms of resistance so it doesn't take too much added resistance in the EOS switch to degrade the flipper power. If an EOS switch is not making contact at all the flipper will likely not flip, but will hold if you manually actuate the flipper.
#Flipper switch dirty. For EM games, flipper power is provided through the flipper switch. Added resistance of a fouled switch can weaken flippers.
#Coil sleeve worn or dirty. Cleaning the coil plunger and sleeve will improve flipper performance. Some older games had metal sleeves that should be replaced with modern nylon sleeves. Even when wear can not be seen, replacing the coil sleeve often helps.
#Coil stop or plunger mushroomed. Coils operate best when there is a flat surface between the plunger end and the coil stop. A mushroomed coil stop or plunger can cause the flipper to buzz when held up.
#Flipper spring too tight. This can also result in noisy flippers when held up. The flipper spring should be adjusted so that it can barely return the flippers to their resting postion when the playfield is up.
#Flipper bushing binding. A worn flipper bushing or a misadjusted flipper bat can result in binding that impedes flipper movement. Make sure there is a small amount of vertical play in the flipper to prevent binding.
#Hogged out fiber link. Over time the holes in the flipper links can become elongated. The play in the flipper movement results in wasted coil movement and thus reduced flipper strength.
#Power issues. Make sure you are getting full voltage at the flipper coil. Usually a power problem will cause both flippers to be weak.
#Drive transistor bad (SS only) In solid state games it is possible to have a transistor that is bad but still somewhat operational. Usually the bad transistor will get noticeably hotter than other similar transistors.
#Power Winding bad. Coil failures are rare, but check from broken solder connections and broken coil wires at the coil lugs.

=Changing Batteries=
Solid state machines have batteries to save high score and setting information when the machine is powered off. Usually these are three AA batteries mounted on the CPU board. They should be changed annually to prevent leakage that will damage the CPU board.

Batteries can be changed with the machine powered on so that settings are maintained. Some people recommend changing one battery at a time, but this is only to help ensure that the new batteries are installed with the correct polarity.

The best thing you can do for your game is to install a remote battery holder, which moves the batteries completely off of the CPU board. See the specific game system section for instructions to perform this simple modification.

[[File:RemoteHolderWiresTooShort.jpg|200px|thumb|left|This remote holder should have been installed with longer lead wires. As can be seen, the holder rested on the System 11 MPU's lamp matrix current limiting resistors, and melted a bit.]] 
When installing a remote battery holder, make sure that the wires leading to it are long enough for the holder to lay comfortably below all circuit boards. This is important for two reasons. First, should the batteries ever leak, they won't be able to "drip" onto the circuit board. Second, the battery holder won't be subjected to heat, as shown in the picture at left.
 

=Abating Alkaline Corrosion=
[[File:AlkalineBatteries.jpg|200px|thumb|right|Alkaline batteries on a WPC MPU. Gack!]]

Leaky alkaline batteries are the number one killer of pinball MPU boards. Although this corrosion is often called "acid damage", there are no batteries used in pinball machines that are acid based. All batteries are either alkaline or lithium based. Lithium batteries are not thought to leak with quite the frequency of alkaline batteries, but the best rule of thumb is "all batteries leak".

The best options for avoiding alkaline corrosion damage to expensive or impossible to replace MPU boards are:
#Remotely locate the batteries
#Use a lithium battery instead of alkaline batteries
#Use a "SuperCap" capacitor (1uf, 5.5V) that charges while the game is on and powers CMOS RAM between power on cycles
#Replace the static RAM on the board with an non-volative RAM (NVRAM)
 

Abating alkaline damage is quite a bit of work. The steps are:
[[File:ConformalCoating.jpg|200px|thumb|left|A Silicon based conformal coating that does a nice job of encapsulating the bare copper.]]
[[File:ConformalCoatedBoard.jpg|200px|thumb|right|A professionally cleaned up board that has been conformal coated. The machine pin SIPs and header pins were protected prior to spraying the conformal coating.]] 
#Assess the extent of the corrosion to judge economical viability of repair. Some boards are so corroded that they are simply impossible to repair or the cost of the repair would exceed the cost of sourcing a new board.
#Carefully examine the board, identifying all damaged parts and traces. Darkened traces are alkaline corrosion that has intruded under the solder mask.
#Remove all corroded parts. If lucky, the solder side of the board won't be corroded. Corrosion changes the solder in such a way that it can't be heated effectively to remove the part. It is sometimes easier to clip the parts from the board and then heat each lead individually to remove them.
#It's sometimes easier to remove more parts than just the corroded ones so that a larger or more convenient area can be prepared for sanding.
#Using sandpaper (200 to 440 grit, YMMV) carefully sand all corrosion from the board. The traces must be left bright and shiny. This is delicate work. Be careful to not sand completely through the traces. The point where traces connect to IC through holes is particularly delicate. Sometimes, a trace is so far gone that there is no way to preserve it while removing corrosion. In this case, the trace will need to be rebuilt with trace wire. Use your DMM to "buzz" affected traces to ensure good continuity remains. It is possible to use a pad sander or even a flap sander on a Dremel tool (only recommended for old, big trace boards like classic Bally/Stern MPUs), with fine grit sandpaper to speed this process. Other abrasives to consider are "lamp socket cleaner sticks" (essentially an abrasive crayon) and fiber glass pencils.
#Suck solder from all damaged "vias". A via passes an electrical signal from one side of the board to the other. Leaving corrosion in a via provides a source for corrosion to get started again.
#Using a mixture of white vinegar and water (50/50), wash the affected area of the board. It's best to limit exposure of the vinegar/water to the smallest area of the board possible as this mixture has it's own corrosive properties. Rinse ALL of the vinegar/water from the board with isopropyl alcohol or a LOT of water. Every bit of the vinegar/water must be washed from the board. Vinegar is used because it's an acid. We use acid to chemically inert the alkaline, as you'll remember from your high school chemistry class (ahem...).
#Either "tin" every bit of bare copper by melting solder on the trace and sucking it off, or use a "solder through" conformal coating to seal the copper. If using a conformal coating, be careful to not spray header pins or inside of sockets. Unless the newly cleaned traces are protected via one of these methods, the copper will begin to oxidize fairly rapidly.
#Use sockets when replacing integrated circuits.
#Install new parts as necesssary.
 

=Coil Chart=

Information on many common coils, including the winding resistance is available at
http://flippers.com/coil-resistance.html

This information is helpful to check if the resistance measured on your coil is in the right range and can also help find a substitute coil that is close to the same strength.

=Lamp Chart=

{| class="wikitable sortable"
!Lamp
!Voltage (V)
!Current(A)
!Candle Power
!Life (hours)
!Base
!Typical Use

|----
|44
|6.3
|0.25
|0.9
|3,000
|Miniature Bayonet (BA9)
|Common GI and controlled lamp bulb

|----
|47
|6.3
|0.15
|0.5
|3,000
|Miniature Bayonet (BA9)
|A low-power version of the #44; reduced heat and candle power

|----
|55
|7.0
|.41
|2.00
|500
|Miniature Bayonet (BA9)
|Used on some EM games, high current, heat and candle power compared to #44 and #47 '''Not a good replacement in pop bumpers or behind backglasses (too much heat generated)'''

|----
|63
|7.0
|.63
|3.0
|1,000
|S.C. Bayonet (BA15s)
|Used in early Williams solid state games like Flash. Found in Williams games as late as High Speed; typically installed in series

|----
|67
|13.5
|.59
|4.0
|5,000
|S.C. Bayonet (BA15s)
|Exclusively used as flash lamps on Gottlieb (Premier) games

|----
|73
|14.0
|.80
|.30
|15,000
|Wedge (T 1-3/4)
|A low-power alternative for the 86 used in Twilight Zone's clock mechanism

|----
|86
|6.3
|.20
|.40
|20,000
|Wedge (T 1-3/4)
|Small lamp used in Creature from the Black Lagoon ramps and Twilight Zone's clock mechanism;Gottlieb Victory ramp chaser lamps

|----
|89
|13.0
|.58
|6.00
|750
|S.C. Bayonet (BA15s)
|Flash Lamps on many Sys11/DE/WPC

|----
|159
|6.3
|.15
|.34
|5000
|Wedge
|A low-power version of the #555; reduced heat and candle power

|----
|194
|14.0
|.27
|2.00
|1,500
|Wedge
|Whitewater Topper Lamps 
Can be acquired at automotive parts stores (instrument panel / dash lamps)

|----
|199
|12.8
|2.25
|32.00
|1500
|S.C. Bayonet (BA15s)
|Alternate for 1156 lamp

|----
|313
|28
|0.17
|3.5
|500
|Miniature Bayonet (BA9)
|Used for lower playfield illumination on Black Hole and Haunted House

|----
|447
|6.3
|0.15
|0.5
|3,000
|Wedge
|A low-power version of the 555; reduced heat and candle power

|----
|455
|6.5
|0.5
|N/A
|500
|Miniature Bayonet (BA9)
|Blinker

|----
|545
|6.5
|0.31
|N/A
|500
|Wedge
|Blinker - used in Twilight Zone, Dirty Harry, No Good Gofers

|----
|555
|6.3
|0.25
|0.9
|3,000
|Wedge
|Common GI and controlled lamp bulb

|----
|906
|13.0
|.69
|6.00
|1000
|T-5 Wedge
|Flash Lamp

|----
|1156
|12.8
|2.1
|32.00
|1,200
|S.C. Bayonet (BA15s)
|High Speed II beacon lamp and Creature from the Black Lagoon hologram projection lamp 
Can be acquired at automotive parts stores (reverse and front turn signal lamp in some vehicles)

|----
|1251
|28.0
|.23
|3.00
|2,000
|S.C. Bayonet (BA15s)
|Pin-Bot and Cyclone Flash Lamps

|----
|1683
|28.0
|1.02
|32.00
|500
|S.C. Bayonet (BA15s)
|High Speed, F-14 Tomcat, and Rescue 911 beacon lamps; Fire! flame tube projection lamp

|----
|1847
|6.3
|.15
|.38
|5,000
|Miniature Bayonet (BA9)
|Dimmer, longer lasting version of 47 bulb; for areas where vibration is a factor (pop bumpers, etc.)
|}

Notes:
#A "blinker" is a lamp with an internal thermal switch (a bi-metallic strip) that interrupts power to the lamp causing it to blink on and off; the cycle is usually a few seconds. These are often used behind the title on EM games. A "flash lamp" is a lamp that is purposely over-driven for a brief instant (milliseconds) to produce an extremely bright flash of light. These are used to draw attention to game features such as bonuses.
#47 lamp is often used as a replacement for 44 lamps where heat is a concern for backglass or plastics.
#447 lamp serves the same purpose replacement for 555 lamps.
#Candlepower is measured in Mean Spherical Candlepower (MSCP)
#T-3 1/4 refers shape and size, for example T-3 1/4 is "tubular", 3.25 8ths of an inch in diameter

Detailed specifications on lamps is available at [https://www.interlightus.com/ Interlight] Just enter the lamp number in the "Bulb Search" field.

=Lamp Sockets=

Some later games have illuminated buttons for start and possibly other functions. These are typically located on the front of the cabinet. Instructions on replacing the lamp in those switches can be found [http://na.suzohapp.com/pushbuttons/installation_illuminated.htm here].

=Fuse Table=

<center>'''Pinball Machine Fuse Table'''</center><center>Some games may have different fuses and quantities</center>

{| width="100%" border="1" align="center"
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Bally EM'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Gottlieb EM'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Williams EM'''
|-
| width="4%" align="center" | 2
| 5A
| BR, DC coils
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 2A SB
| Drop target bank
| width="4%" align="center" | 6
| 10A
| Main, BR, coils
|-
| width="4%" align="center" | 2
| 8A
| Main line fuse
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 5A SB
| Main line fuse
| width="4%" align="center" | 6
| 15A
| Lamps, coils
|-
| width="4%" align="center" | 4
| 10A
| Coils
| width="4%" align="center" | 4
| 10A
| Lamps
| width="4%" align="center" |
|
|
|-
| width="4%" align="center" | 4
| 15A
| Lamps
| width="4%" align="center" | 4
| 15A
| Coils
| width="4%" align="center" |
|
|
|- align="left"
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Atari'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Bally/Stern (1977-1984)'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Gottlieb Solid-State'''
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 1A SB
| Power supply
| width="4%" align="center" | 3
| bgcolor="lightgreen" | 1A SB
| Coils-under PF
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 1/4A SB
| Displays
|-
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 2A SB
| Service outlet
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 3A SB
| Main line power
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 1A SB
| Coils, Drop target bank
|-
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 5A SB
| Main power
| width="4%" align="center" | 1
| 3/16A
| High Voltage on SDB
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 2A SB
| Pop bumpers (Sys80/80A/80B), Drop target bank
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 7A SB
| Power supply
| width="4%" align="center" | 1
| 3/4A
| Display power supply
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 5A SB
| Main, coils, lamps
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 10A SB
| Power supply
| width="4%" align="center" | 1
| 4A
| 12v/5v power supply
| width="4%" align="center" | 2
| 8A
| Lamps
|-
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 15A SB
| PS, lamps, displays
| width="4%" align="center" | 3
| 5A
| Coils
| width="4%" align="center" | 1
| 10A
| Lamps
|-
|
|
|
| width="4%" align="center" | 2
| 15A
| General Illumination
|
|
|
|-
|
|
|
| width="4%" align="center" | 1
| 20A
| Switched Lamps
|
|
|
|-
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Williams L3-L7 (1977-1984)'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Williams System 9-11 (1985-1990)'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Williams WPC (1990-1994)'''
|-
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 1/4A SB
| Display high voltage
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 1/4A SB
| Power supply (displays)
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 3/8A SB
| Display driver board
|-
| width="4%" align="center" | 3
| bgcolor="lightgreen" | 2-1/2A SB
| Coils
| width="4%" align="center" | 5
| bgcolor="lightgreen" | 2A SB
| Aux board
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 3A SB
| Coils, flippers
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 4A SB
| Sound board
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 2-1/2A SB
| Coils
| width="4%" align="center" | 3
| bgcolor="lightgreen" | 5A SB
| Power supply, lamps
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 7A SB
| 5v power (L7 games)
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 4A SB
| Coils, flippers
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 7A SB
| Power supply
|-
| width="4%" align="center" | 2
| 8A
| Main, switched lamps
| width="4%" align="center" | 6
| bgcolor="lightgreen" | 5A SB
| Flpr, aux, cab, lamps
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 3/4A SB
| 12v power supply
|-
| width="4%" align="center" | 2
| 20A
| General illumination
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 7A SB
| Power supply
| width="4%" align="center" | 2
| 8A
| Main, switched lamps
|-
|
|
|
| width="4%" align="center" | 2
| 1/10A
| Cabinet, displays
|
|
|
|-
|
|
|
| width="4%" align="center" | 1
| 3/4A
| 12v power supply
|
|
|
|-
|
|
|
| width="4%" align="center" | 2
| 8A
| Main, switched lamps
|
|
|
|-
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Data East'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Sega & New Stern'''
| bgcolor="darkgray" align="center" | Qty
| colspan="2" bgcolor="darkgray" align="center" | '''Williams WPC-95 (1995-1999)'''
|-
| width="4%" align="center" | 3
| bgcolor="lightgreen" | 3A SB
| Coils, flippers
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 3/4A SB
| Display
| width="4%" align="center" | 2
| bgcolor="lightgreen" | T0.315A SB
| Display
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 4A SB
| Coils
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 3A SB
| Coils, flippers
| width="4%" align="center" | 1
| bgcolor="lightgreen" | T0.63A SB
| 12v PS F101
|-
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 5A SB
| Lamps, power supply
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 4A SB
| Power supply
| width="4%" align="center" | 5
| bgcolor="lightgreen" | T4.0A SB
| Cls,5/12v,lmps,flsh,flpr,ln
|-
| width="4%" align="center" | 2
| bgcolor="lightgreen" | 7A SB
| Power supply
| width="4%" align="center" | 4
| bgcolor="lightgreen" | 5A SB
| Coils, lamps
| width="4%" align="center" | 1
| bgcolor="lightgreen" | T5.0A SB
| Switched lamps, line
|-
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 8A SB
| Line, power supply
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 7A SB
| Coils
| width="4%" align="center" | 1
| bgcolor="lightgreen" | T6.3A SB
| Coils main F108
|-
|
|
|
| width="4%" align="center" | 1
| bgcolor="lightgreen" | 8A SB
| Power line, lamps
| width="4%" align="center" | 2
| bgcolor="lightgreen" | T2.5A SB
| Audio F501, F502
|}

=Resistors=
Resistors typically have a standard color coding scheme, (the exceptions are some power resistors which have the value and wattage inked on the resistor), which is used to identify the resistor's value and tolerance. The resistor's value and tolerance can be identified on this [http://samengstrom.com/24614782/en/read/4_Band_Resistor_Color_Codes?history=5107960,24614782 website] by clicking the appropriate color bands.

Generally when replacing resistors you should match the original's tolerance. You can go down (tighter) in tolerance and up in wattage slightly without any difficulties (excepting physical size limitations). In some applications an increase in wattage is recommended (some display and driver boards).

A resistor can be tested in circuit, but depending on the circuit, an accurate reading may not be measured. Just be aware of this characteristic and don't assume that a wildly off reading means the component is bad. Remove one lead of the resistor from the circuit to get an accurate reading in this case.
 

=Capacitors=
[[File:capacitors-old-vs-new.jpg|thumb|left|250px|Comparison between old and new axial electrolytic capacitors]] 
There are a handful of different types of capacitors. In this case, the discussion is focused on the cylindrical electrolytic capacitors. Electrolytic capacitors are filled with an electrolyte material, which can dry out over time, leading to the capacitor to lose capacitance and cause various problems within a game.

When replacing old capacitors, be sure to pay attention to the polarity, if the capacitors are polarized (most are, but not all - see bipolar capacitors). Most capacitors are labeled in some way, usually with an arrow down the side of the capacitor pointing to one of the terminals. Likewise, electrolytic capacitors have a concave ring near one of the ends. Do not depend upon that ring to indicate polarity--just ignore it. Most of the time, the ring is on the positive side of the capacitor.
 

==Testing Capacitors==
To test aged capacitors (or newly purchased capacitors to make sure they're not fake), there are testers that test a capacitor's capacitance. A [http://www.peakelec.co.uk/acatalog/jz_esr70.html Peak Atlas ESR70] is one such tester that isn't too expensive and is available from a variety of resellers.

==Buying Capacitors==
Make sure to buy capacitors from reputable resellers. Some cheap, disreputable, and/or overseas retailers can sometimes sell counterfeit capacitors, such as these:

<gallery widths="250px">
File:capacitor-fake-stacked.jpg|This capacitor actually has two smaller/cheaper capacitors stacked inside of it. The giveaway is the presence of two concave rings--legitimate polarized capacitors only have one concave ring.
File:capacitor-fake-filter.jpg|This large filter capacitor actually has a much lower-rated capacitor hidden inside of the larger casing. The only way to check for this is to use a capacitor tester.
File:capacitor-fake-misspelled.jpg|Sometimes, fake capacitors have labels that look like well-known brands at first glance that go so far as to use a similar font or logo, but are slightly misspelled. In this example, Rubycon is a well-known brand, but instead, this capacitor has "Rulycon" on the label. The misspelling indicates that it is a fake.
</gallery>

=Game Software (ROMs)=
The code used for solid state games is generally stored in EPROM chips that are located in sockets on the PCBs in the head of the pinball machine. Separate ROMs are used for CPU, sound, and display, and more than one chip may be used for each. Code is updated as bugs are found and features are added. In a few cases special home versions of ROMs have been released containing more modes and special features. These home versions are set to allow free play only. In any case, it is a good idea to have the latest version of software running on a machine. Game code can be found at manufactures web sites and burned to an EPROM. Most people do not have access to a ROM burner and these chips can be ordered from many [[Pinball_Parts_Suppliers |pinball parts suppliers.]]

Updating the software is usually as simple as removing the old chips and installing the new ones. ROMs are notched on one end. Be sure to insert your new ROM with the notch at the same end as the one you removed. ROM sockets are notched also. DO NOT depend on the labels on the replacement roms "matching" a direction on your machine! ALWAYS check the orientation based on the notches. Sometimes there is a need to have minor board modifications to allow for a newer type ROM. An example of this is the jumper installation needed on [[Funhouse |Funhouse]] for a larger ROM size. Check to make sure your new ROM is a direct replacement.

Take care when removing the old EPROM chip. Do not pry the old chip up with a flat head screwdriver - or use caution while working from both ends when doing so. A chip puller is the safest way to remove the old chips. When installing the new chip gently press in each end of the chip until it is fully seated. Make sure all pins are lining up with the chip sockets.

Newer Stern machines allow game code to be upgraded via USB transfer and no ROM burning is required.

=Counterfeit Integrated Circuits & Blacktopped Parts=

[[File:MOS 6532.JPG|300px|left|thumb|Bogus 6532 Chips]]
[[File:BlackTopped6821Cropped.jpg|300px|right|thumb|The "overspray" and perfectly black top on this 6821 should raise suspicions.]] 
As time passes, the need for through hole integrated circuits (IC chips) in current manufacturing decreases. Most consumable electronics today are using surface mount ICs. However, through hole ICs are what nearly 90% of all solid state pinball machines use on circuit boards. And as the need decreases, the price increases. Enter the counterfeiters. It may sound absurd, but there is a whole "underground" industry of counterfeit IC chips being created. How are they typically counterfeited? Old ICs are sourced, the top of the chip is either sanded or painted over with the correct identifiers as to what chip it is, and a new identifier is inked over. Some counterfeit chips are fairly obvious (see the pic to the left to view two sanded IC tops), while others are not so obvious. 

[[File:DoubleNotched6821.jpg|300px|left|thumb|This 6821 has a "pin 1" notch on both ends. While certainly odd, this part was not a counterfiet. Image courtesy of Jerry Clause.]] 
The moral to this is know who you are buying from. Avoid buying components from sellers who offer product at "too good to be true" prices. Some of these types of sellers peddle their product on eBay, and originate from the Far East. Keep in mind that even trusted sellers are not totally immune from counterfeit chips, but the really good sellers have a better grasp on reducing the sales of counterfeit chips from their inventory.
 

TO-3 form factor devices have gone or are soon going out of production. A great number of those on the market today are counterfiet. They may "diode test" correctly and may even work as long as the current draw remains low. However, they will not work for pinball machine needs and will quickly fail.

One good way to identify a counterfeit part is to apply acetone (finger nail polish remover) to the inked label on the part. The label will smear easily if the part is counterfeit. The label will be unphased if it is not counterfeit.
<center>
<gallery widths=300px heights=400px perrow=2 caption="Real vs Counterfeit LM323K parts, decapped.">
File:RealLM323K.jpg ‎|<center>Note the dual and beefier "bonding wires" used in a real LM323K. Images courtesy of PinSider Tuukka</center>
File:FakeLM323K.jpg |<center>This counterfeit part was marked LM323K. It is clearly a fake/mismarked part. Note the single/small "bonding wires".</center>
</gallery>
</center>

=Tumbling Parts to Clean Them=
[[File:TarnishedMetalPosts.jpg|200px|left|thumb|A batch of playfield posts, etc from a Gottlieb Buckaroo.]] 
A quick way to shine a lot of metal parts is to use a "parts tumbler". (Technically, what is referred to in this section is a Vibrating Polisher - the name comes from a rock tumbler polisher, which can also be used but takes much longer.) Tumblers can typically be purchased at Bass Pro Shops as shooting enthusiasts use them to polish brass cartridges. One of the "old standards" is the [http://www.berrysmfg.com/product-i14546-c47-g8-b0-p0-400_Tumbler.aspx model 400 made by Berry's Manufacturing]. Crushed walnut shell media works well. It can be acquired at pet stores where it is sold as lizard bedding. For gentle less aggressive tumbling, use corn cob media. Additives such as "Flitz" or even a squirt of Novus 3 have been used to improve results. KIT Scratch Out also works very well for this application.
 

[[File:TumbledBuckARooPosts.jpg|200px|left|thumb|Ah yes...nice and shiny. These parts were tumbled for about 24 hours in crushed walnut shell media.]] 
Tumbling approaches the point of diminishing returns after about 24 hours. Tumbling past 24 hours doesn't yield much improvement.

To remove the walnut shell media from flat-blade screws, a dental pick works well. 
To remove the media from Gottlieb "Speed Nuts" or Acorn Nuts, shake them inside a plastic container. The media falls right out.
 

=How to Properly File Switch Contacts=
:First off, if the switch is in a solid state machine and is not a high power switch (flippers and some pop bumpers), DO NOT file it. It's a gold plated switch, and you will ruin the switch contact by filing it. Don't look at the existing switch and assume that because you see it's gray, that it's a high power switch.

:Instead, pinch the switch contacts together and run an index card or dollar bill between the contacts a few times.

 

=Tuning a Game for Best Performance=

==General==
:Check the tightness of all under playfield mechanisms. It's not uncommon for mechanisms (even with lock nuts) to loosen up over time. Do not overtighten and strip out any holes, just snug them in. If you find any loose holes, repair with glue and toothpicks. Once everything is tight again, mechanism action will be crisper. Do not assume that the mechanism was originally installed perfectly - slight alignment tweaks can improve action.

==Leveling the Game==
:One of the most important things you can do to tune a game is make sure the playfield is level side to side. Some games contain a bubble level on the apron to check side to side leveling. Do to differing floor conditions, any time a game is moved, the level should be checked. Use an inclinometer or small torpedo level to check the side to side level. An inclinometer application can be used on a smartphone as well. Check the level on the playfield itself, NOT on the playfield glass. The playfield may not sit level in the cabinet or may be warped. Check the the level at several points on the upper and lower playfield. Adjust using the leg levelers. After you're done, make sure you tighten the locknuts on the levelers tight against the bottom of the leg.

==Adjusting the Game Pitch==
:The pitch of the game drastically affects game play. A steeper game plays faster, but too much and it will be hard to shoot ramps. A shallow pitch slows the game down, and the ball will be more likely to move side-to-side. Too shallow can also allow the ball to be redirected more by playfield irregularities, such as warped inserts.

:Due to differing floor conditions, any time a game is moved, the pitch should be checked. The proper pitch of a given game may be indicated in the manual. In the case of games which include a bubble level for pitch, the manufacturers recommendations may be marked on the level. For a Williams game, the manufacturer recommends getting the nose of the bubble between the first and second mark. The marks represent one-half degree. For Stern, Data East, and Sega games, the bubble should be between the lines.

:When a recommended pitch is not indicated, the "Rule of Thumb" is 3 1/2 degrees for EM games and 6 1/2 to 7 degrees for solid state games. Use an inclinometer on the playfield itself to measure pitch. Adjust using the leg levelers. After you're done leveling, make sure you tighten the lock nuts on the levelers.

:Some players will adjust the pitch outside of "Factory" settings, to suit their taste or playing style. After playing a game for a while on the "standard" settings, you may wish to experiment with different pitches.

:A pinball game should also be level side to side. Measure on the playfield, not on the glass.

==Balls==
[[File:FacetedPinball.jpg|200px|thumb|left|This ball is almost "faceted". It was pulled from a modern Stern game after only about 100 plays.]] 
:Inspect the balls in a game regularly to ensure none are pitted or becoming rusty. A damaged ball has the potential to strip playfield ink in a very short time. Keep the balls clean and polish them occasionally with a soft cloth; try not to put balls back in the machine that have skin oil on them. Transfer from the cloth directly to the machine.

:The more close to round a ball is the better/more wild it will play. Balls are just ball bearings, and are manufactured to tolerances up to .001%. You don't need a ball that true to put in a pinball, but if you can afford them, they would play very well. Buying pinballs from a reputable supplier is fine; a pinball costs between 90 cents to 5 dollars depending on finish and tolerance.
 

==Adjusting flippers==
:Nothing impacts a game's performance more than the performance of its flippers. The entire game can be smooth playing and work properly, yet with bad flippers no one will enjoy it to its full potential. The proper rebuilding and tuning of flippers impacts a game's performance about 70% vs. 30% for all the other parts in the game.

:High voltage end of stroke switches need to be filed flat or replaced and should open with between 1/8"-1/4" gap at full extension. Flipper cabinet switches need to be filed and dressed as well, provided they are heavy, tungsten contacts. '''Do not''' file cabinet switches of games which use solid state flipper assemblies. These switches are gold plated. Filing will remove the plating and ruin the switch. For those switches, draw an old business card between the contacts as you pinch them together. This will clean the contacts sufficiently. Any connector in the flipper power path should be replaced or eliminated if possible (for instance, games that use spade lugs to attach their flipper button blades should have their wires soldered directly to the blade instead). Flipper relays need to be cleaned and contacts dressed as well, and their solder mount points re-flowed.

:The angle of the flipper should be adjusted to the slope of the inlane guide (if present) and the inlane guides tweaked (either by slight movement or bending if wire type) so that no ball hop off the lane guide occurs. This issue is especially prevalent on Bally games with wire guides and early Williams' solid state games with flat metal guides; the flat metal edge gets hammered over the years as well as the guide itself loosening in its mounting screws cause it to sit lower than intended. Games without inlane guides should be checked against a reference (flyer) picture to determine the proper play angle, but some leeway is permitted here in the interests of gameplay. Under no circumstances should an opposing pair of flippers be adjusted so that one rests higher/lower than the other, nor both flippers extended not be at the same height.

:The flipper bat should have a slight up-down play as you pull away from the playfield at both its rest position and extended position. Swapping worn parts from left to right or the reverse can help you re-use worn parts where replacements are not available. Rebuild and redress any worn out parts if at all possible. Reverse all hacks over the years to restore the play to its original intentions.

:Some mechanisms (Bally linear flipper mechanism spotlighted) benefit from having earlier style parts (plunger, link, and pawl) swapped into their assemblies for better flipper action. The linear flipper while fine when new has a fast-wearing part in the form of the nylon bearing on its lever assembly; the earlier style parts swap in place no problem and last much longer, as well as being a zippier flip thanks to the lighter mass of its parts.

==Adjusting drop targets==
:Most drop targets are made of plastic and are made to run 'dry', i.e. no lubrication. If you must lube them, use graphite powder or a lube specifically made for plastic on metal. Note that any lube used will tend to make the area under the playfield very messy so use very sparingly if at all. The first order of business is to disassemble the drop mechanism and clean every part very, very well. For metal parts use a metal polish to make sure there are no really sharp edges or burrs to cause wear. You might have to use a small file to dull any sharp edges. Plastic drop parts polish with Novus 2 after cleaning any grease off with a degreaser safe for plastics (simple green works well). Take caution in cleaning the drop target face. If a face is stamped with artwork, most chemicals (even mild ones) will remove the artwork.

:Adjusting a drop bank so that a balancing act is performed can be a bit of an art; you want the least resistance to dropping and resetting possible while still maintaining all drops resetting properly every time. There's nothing more frustrating from a player perspective than making a good shot on a drop target and it not dropping. If adjusted properly a bank can be 'swept' with an oblique flipper shot, all drops including the stubborn tending Williams and Bally drops will sweep if clean and adjusted carefully.

===Williams===
:Williams targets with contacts that ride on a circuit board would benefit from a very light application of DeOxIt. (Replacement boards are available from [https://www.siegecraft.us/presta/index.php?id_product=21&controller=product&id_lang=1 Siegecraft]) The later targets that depend on a copper blade for forward tension you can use teflon lube on the copper blade; wipe it on with your finger and wipe almost all of it off. You want the least amount of lube possible. The copper blade can be bent but be careful as the blade should be flat along its length; you want JUST enough tension so the target presses forward, but not so much that the target won't fall when you hit it.

:When you reassemble Williams drop banks, do not over tighten the screws that hold the metal bars to the plastic bosses - you will ruin the tension on the drop bank and possibly crack the screw boss, rendering it useless (these parts are currently unavailable new). Just snug the bar down to the drop bank and let the lock washer do its job holding it on.

:Later Williams' drop banks went to a two-spring design, one to pull the target down, and one coil spring to push the target forward on reset. This design started sometime around the Big Guns era. There's not a lot of adjustment needed in this type of target other than to clean them very well, and to ensure that the rubber grommets and the washer/screw combination are not too tight. They should be tightened just enough so the target will reset properly, but not so much that the target drops slowly. The weak points of this design are the ledge the drop targets rest on, and the studs used to hold the drop target reset coil stop. Originally, a small strip of tempered, spring steel was used for the ledge. This piece of spring steel was riveted to the drop target assy. frame. If it cracks or breaks, a single target or targets in the bank will not properly reset, as there is no ledge for them to rest in the up position. Williams realized this issue, and later versions of this type of drop target assy., somewhere around Earthshaker, were made with a replaceable ledge. Likewise, the coil stops were mounted with studs integrated into the drop target frame assy. These studs can snap off flush with the frame, allowing only one side or neither to hold the coil stop in place.

===Gottlieb===
:Gottlieb drop targets are the best designed and built targets in the business. As usual, Gottlieb didn't cut corners with their original design. There are 2 discrete springs used; one to pull the drops in the proper direction to reset correctly, and another to provide the correct spring tension on the pulldown stroke. Additionally, the reset mech is mounted at an angle so the drops reset smoothly and correctly. Gottlieb drops should be adjusted to reset approximately 1/16 of an inch "above" the bank's top plate. You can loosen the reset coil mounts to slide the coil into place to accomplish this. Letting them reset too high (caused when the coil mount migrates to the bottom of its travel) will tend to break off the "foot" on each drop target. Once this happens a Gottlieb drop can reset in a very awkward position, higher than it should be; a snappy ball hit when it's in this position often will snap the target in 2.

:The 2-spring Gottlieb design changed during the system 80B era. This design change moved the reset coil from the outside of the drop target assy. to the underside, center of the assy. on small and single banks. Multiple reset coils were still used on banks larger than 4 targets. The benefit of the new design was less moving parts and a slightly smaller mounting footprint. However, the newer design eliminated the two spring design, and the smooth even stroke for the reset. While the targets still drop down smartly, on reset occasionally they will reset too high, or some targets will fail to reset, if the reset coil is not adjusted properly. Well beyond the time of the initial design change, some System 3 games use a combination of the old and new style drop target assys.

===Bally===
:Bally drop targets come in 2 varieties - "tombstone" and "flattop". The flattop ones were designed for games that use an inline drop target assembly (Paragon, Fathom, Eight Ball Deluxe, others) or a single drop target where the ball travels over the drop target (Flash Gordon, Rolling Stones, others). The flattop targets that have a ball path over them need to be adjusted so the target top is flush with the playfield so the ball can travel over them easily. On a single drop, you can bend the foot that's under the drop target stem to accomplish this, or loosen it and move it up or down to accomplish the same thing. On an inline bank mechanism, you want to adjust the bottom foot plate to do the same thing, which can be difficult for the center targets. Some experimentation is necessary here.

:For Bally flattop drops that aren't in an inline configuration you want the drop to sit very slightly above the playfield surface (1/16 inch or less) - this is so a ball will not tend to get stuck in the slot formed by the target spaces and the playfield. Adjusting the height the drops rest at can be accomplished by moving (or bending) the foot plate or adding a spacer made out of shims (cardboard, thin metal, etc.) Install the shim on the top of the bottom frame where the foot of the plastic target rests. You can use tension clips or even a paper clip to hold your shim in place. Be sure any added shims don't interfere with the operation of the targets or reset mechanism.

:The thickness of the Bally drops sometimes cause what's called "bricking" of the drop targets - a hard shot to the drops will result in the ball bouncing off the target (sometimes snapping it in half!) but the drop not dropping. There are a couple things you can try to fix this, but there's no one definitive solution that works (other than swapping in a Gottlieb target bank if you can!) - some of the things you can try are shaving a minute angle into the drop shelf where the target sits at rest under tension, changing the angle of the spring, changing the tension of the spring, and moving the entire bank inside the slot as far forward as possible. Some more radical solutions over the years have been tried to fix this issue. Adding extra springs, epoxying spring steel to the back of the target, melting notches into the target with a soldering iron, beveling the under playfield area with a chisel, changing the rubber behind the targets (fat rubber makes the bricking worse), and changing the posts behind the targets to a smaller size have all been tried with varying degrees of success, but none have fixed the issue 100%.

:The newness of the drop target seems to be directly proportional to its propensity to brick; the older the drop, the more it tends to drop smoother because of years of wear. This is particularly poignant with classic Stern drop targets; they are similar to Bally drops but the reset shelf is lower on the target itself; a Stern drop can be modified to work in a Bally machine, by shaving this rib off, but not recommended as classic Stern drop targets have not been available in the "chiclet" style for over 25 years.

===Stern (Classic)===
:Classic Stern drops, commonly referred to as "chiclets", were originally similar to the Bally "tombstone" style, and worked well (overall the non-flattop style of drop works well in terms of non-bricking, but often a ball could be come trapped between targets). During the production run of Meteor the top six bank drop style changed from the chiclet style to the flattop style. All subsequent games after Meteor used the flattop style. All previous games used the chiclet style.

:Adjusting the down position of the targets is similar to the flattops but with slightly more height vs. the playfield, 3/32" vs. 1/16". A radical solution to this if you get this problem constantly would be to glue a piece of wood cut to fit between the targets and the slot and glued into place eliminates the gap that the ball gets stuck in, but this is a very radical solution and not recommended for most machines.

:The metal parts on classic Stern drop mechanisms tend to wear and need metal cleaning/polishing to be refurbished properly. Teflon lube should be used very sparingly (wipe on, wipe almost all off.... if you can see it, it's too much) on any metal to metal contact points. Any metal coil sleeves used in drop mechanisms should be replaced with the proper sized nylon sleeves instead. The metal fingers where the drop targets contact their switches need a slight bit of lube also, less than used anywhere else. The switches themselves need to be adjusted to provide the least amount of drag to the dropping finger but still also contact enough pressure to provide some wiping action to the 2nd switch contact.

==Tweaking a pop bumper==
:Pop bumpers should be adjusted so the slightest touch of a ball at any point causes them to activate, but not be so sensitive that vibration causes them to activate. Clean the spoon switch actuator very well. If it's plastic you can use novus to polish it. If it's metal some 2000 grit sandpaper will polish it nicely. On solid state or EM machines with high voltage points, you should file the switches clean and flat, then add a slight crown to one of the contacts. On machines with gold flashed contacts, inspect them well and clean with Brasso, alcohol, or a business card wiped between the points. If any part of the gold plating is breached, replace the contact with a new one. Gold plated contacts with missing plating will never be 100% reliable again.

:Adjust the position of the spoon switch underneath the skirt's actuator so that the pin sits naturally in the center of the spoon switch. The spoon switch bracket has oblong mounting holes for exactly this purpose. To see if the pin is in the center, you can press up on the spoon switch from the bottom - if the skirt pin moves, it's not centered. Once it's positioned in the center, tighten the switch bracket mounting screws. Now, using a contact adjuster tool, adjust either the spoon blade itself (for metal ones) or the blade that provides the tension to the plastic spoon so that there's barely tension on the actuation pin (the softer this adjustment, the more sensitive the pop bumper will be). You want enough force so that the spoon re-centers the pin, but not so much that anything other than a hard ball hit activates the bumper. With the playfield raised you can activate the pop skirt by hand to see how much to adjust the spoon. It takes several tries to get this right, but it's well worth taking the time to do this.

:Adjust the second blade to between 1/16"-1/8" gap between the contacts of the first blade. This will vary depending on if the machine uses high voltage activation of pop bumpers or not. You want the gap close enough so the pop is sensitive, but not so close that other mechanisms in the machine activate the pop. A good way to test this is to adjust the switch, then with the playfield lowered, make a fist and pound on the playfield in the area of the pops.

:Some machines that use direct activation of pops might benefit from wiring in a Gottlieb pop bumper driver board. This applies mostly to Gottlieb System 1 solid state machines, but could also be used on some early Williams games as well as specialized purposes on other games. Basically, high voltage activated switches can pit and arc; generally, they require a slightly larger gap to ensure the contacts do not weld together from the arcing. Using a pop bumper driver board on this type of bumper with the actuation contacts changed to gold flashed type allow a closer switch gap, and the board provides a solid activation regardless of how hard the skirt was hit.

:A specialized purpose for a pop bumper driver board would be on a Stern 9 Ball, for the lone pop at the top. Bally/Stern machines do not have the ability to fire more than one momentary solenoid simultaneously; this comes into heavy play on 9 Ball as the drop banks reset and drop their targets. It is possible for the top pop to not fire while this resetting is going on, especially if the game is set to require both 3 bank drops to reset to advance the bonus multiplier. The scenario is this: You drop both banks and the ball hits the pop.... with a thud. You receive score for the hit, but the pop doesn't fire because the 2 3 bank drop targets are still resetting. Changing the pop to activate with a pop bumper driver board removes the hardware limitation from the equation, as the pop is able to activate on its own; the mpu still scores the pop as a secondary switch gets added similar to Gottlieb System 1 games or early williams games.

:For a while Wico made a plastic pop bumper assembly that used a plastic rod and ring combination. This was used on their game Af-Tor and also on Stern machines starting around Cheetah to the end of classic Stern production. This plastic rod and ring weighs much less than the metal assembly normally used, and can be swapped into the metal type with a little effort. The resulting quicker reacting pop is amazing in its smoothness and reaction time; you will get much better pop action with this substitution. It works even better than putting a stronger coil in the metal ringed pop bumper assembly, which will also pop the bumper quicker, but the moving mass of the metal rod and ring still make that combo slower reacting. Game plan may have used this plastic combination for a while also, as did Pinstar's Gamatron conversion kit.

==Tuning a spinner==
:Nothing beats a solid spinner hit, spinning and racking up points at a furious pace. On the flip side, nothing sucks the enthusiasm out of a nice shot more than a spinner weakly spinning a few times lethargically, adding a couple points to your score. There are a couple tricks and techniques to make your spinners spin quick and long.

:First, disassemble the spinner and clean all gunk off the support wires. The cleaner a part is in general the smoother it will operate. Polish the contact points of the support wires with 2000 grit sandpaper and a metal polish such as Brasso, or even Novus 2 (a plastic polish, but will work for this application). You want the support wires as smooth and round as possible. Then, using a very small round file, dress the holes in the spinner bracket so there are no rough edges both inside the hole and on the outside. Smooth is the key here.

:Reassemble the spinner with one plastic disc against the spinner body, the below-playfield actuator wire, then another plastic disc towards the outside of the spinner. The discs and actuator wire shouldn't be 'snug.' There should be a little room for the wire to twist slightly if needed. The spinner should rest with a very slight forward cant, where the top of the spinner is slightly forward of the bottom. Adjust this by bending the spinner wires in the bracket by pushing up or down on the spinner flag itself. If you have the spinner adjusted perfectly perpendicular, the spinner can and will stop 'upside down' on occasion, locking the switch on.

:Take some Teflon lube gel on a toothpick and put just a touch of it at the metal to metal contact point in the spinner bracket. Move the spinner back and forth and spin it to distribute the lube evenly. A simple rule of thumb with the lube is if you can see any, you used too much. Less is more here.

:Adjust the switch blade so the spinner activates near the peak of its spin; you want it to kiss the stationary blade just slightly, with a very slight deflection. Another trick to consider is to change the height of the posts (or add spacers/washers) the spinner bracket rests on to raise the bracket slightly. The more to an edge the ball hits the spinner, the more energy is imparted to the spin. This is also another reason for the slight forward cant on the spinner.

:A spinner can get up to 200 spins with one solid hit depending on the machine and flipper strength, well worth tweaking so it performs at its peak.

==Tweaking Tilt Mechanisms==
:Most would ask why you would want to tune a tilt mechanism. Like it or not, tilt is part of the game of pinball. Unless you remove your tilts entirely, you want them to activate in a fair, consistent manner. There's nothing worse than playing a spirited game and tilting because a solid hit one time doesn't tilt, but yet a light hit later on tilts your ball.

:Disassemble the tilt mech and clean everything really well to remove the gunk and grease. Use a metal polish such as Brasso to polish every part of the mech: The plumb bob, the wire, the brackets (both the top bracket and the round lower bracket). When you reassemble the mechanism, the position you put the plumb bob in makes a huge difference in how the tilt operates. Almost all parts manuals picture the plumb bob inverted (small side down) ABOVE the actuator ring, but almost all games have the bob BELOW the ring instead. Each position causes the tilt mechanism to behave differently.

:The inverted position allows quicker recovery after a tilt; the rod stops moving quicker as the weight is closer to its pivot point. If you like your tilts tight, raising the challenge, the inverted position is the one to use as you can adjust the tilt to a hair level, but not so much that you tilt subsequent balls on a tilt. The disadvantages are that you have to remove the ring to insert the bob correctly, and that if the bob ever loosens up, it will just sit on the ring causing a non-playable machine.

:The "normal" position does not have the issue just described; if the bob falls off, you end up with no tilt. Because the weight is farther along the rod, the tilt adjusted this way takes longer to recover after hits and may in fact swing for a very long time (2 minutes or more depending on the force imparted).

:Regardless of the bob position chosen, you want the bob to be centered in the ring assembly. This can be accomplished by moving the ring if it has slots to do so, or by bending the hanger bracket the rod is suspended from. Sometimes you can flip the ring assembly upside down to obtain a better profile for the bob and ring to meet.

:Shaking a pinball is a part of the game, and possibly a greater factor in making you a better player. If you can impart force to the ball through shaking on a tight tilted machine, you will find yourself a much better player in all situations. Anyone can brute force manhandle a machine with no tilt; it takes skill and finesse to do so on a machine with a hair tilt.

:Another trick is to ensure the playfield is attached solidly in some way to the cabinet. Older games have a metal clamping bracket in the cabinet to lock down the playfield, allowing better nudging action. Some older games use screws to attach the playfield to the cabinet. Metal hanger brackets used on newer machines take some of the nudging force away by allowing the playfield's suspension to absorb some of the force. A piece of cardboard folded and wedged at the playfield apron will help remove this factor and allowing more subtle shaking of the machine. This in turn will allow a tighter tilt if desired since the playfield will react to smaller nudges versus stock.

==Cleaning and Adjusting Rollover Switches==
:Rollover switches should offer little resistance to the ball rolling over them. A ball hang up should never occur on a rollover switch wireform; if it does, the tension on the blade is too great and needs to be backed off. The contact points should be adjusted so the contacts kiss with a very slight wiping motion, and release smartly (to prevent duplicate hits from switch bounce).

:Only clean gold flashed contacts with a business card, Brasso, or alcohol. Never ever file gold plated contacts. Once the gold plating is breached, the switch will never be 100% reliable again. Often early solid state games up until 1984 or so have had their plated switches filed by the original operator who didn't think the warnings in the manual and often printed on under playfield labels to NOT file the switches applied to them. Inspect all switches to see if this has occurred and replace any filed contacts with new.

:Clean the switch wireform actuator well by disassembling it and polishing it with a metal polish such as Brasso. Even though the wireforms are a metal to metal contact, you do not need to use any lubricant on it as it is not a tight metal to metal contact, nor does it need the reduced friction to operate smoothly.

:The switch blade tension should be enough to hold the wireform up but allow it to depress smoothly with any speed rolling ball. Switch blades with bends and kinks in them from improper adjustment should be replaced or straightened as much as possible, and any missing insulating fishpaper should be replaced. If a dead stop blade (has a sharp bend in the middle) is on a switch adjust that instead of adjusting the switch blade its' stopping instead.

:If doing a full teardown of a machine consider replacing all the switches with new. Although very uncommon, it is possible for metal fatigued switches to lose their tension and simply not work correctly. You could even replace the switch and wireform with a new microswitch part although you would lose any tension tuning capability if you do so.

==Tweaking lane guides==
:Lane guides are bent pieces of wire that feed inlanes/other areas of the playfield. They are also formed by plastic hoods that fit over posts, to form channels for the ball to travel. They do not require much maintenance at all, but there are a couple of things to check to ensure they are attached properly and feed the ball in the correct direction.

:The plastic hood over post type doesn't really have any adjustments involved - you need to make sure the posts are held fast to the playfield. If they are lose at all, fill the mounting hole with some kind of wood filler (hardwood dowels and glue works well) and do not over-tighten the mounting screw when you reinstall. For really bad holes or posts that just get hammered (for instance, near pop bumper nests) you might want to consider replacing the wood screw with a machine thread screw and T-nut underneath the playfield. Often lamp wiring would get in the way of this however so check carefully before you upgrade.

:The lane guide can be made to play differently depending on what rings you install on them. A good option is to put a slightly fatter ring on the top post of the guide so you can get bouncier action if you need to shake to get a certain lane. The fatter rubber closes off the lane space slightly, but it makes it easier to nudge to move the ball around, essential on older games without lane change or many, many lanes at the top. A tighter ring can be used on the bottom post of the guide to allow the ball to travel back UP through the lane easier, usually from a lucky pop bumper carom.

:Wire lane guides are usually found directing the ball towards the flippers (inlane guides). The mounting holes can be egged out and again, can be filled and drilled. No glue is needed to hold the wire guide itself in, it's held by friction so when you drill the hole, go one drill size smaller than needed and press fit the lane guide in. Some wire guides have tangs that help hold the guide in correctly. Be careful removing these as they tend to rip up the top ply of the playfield surface. Use something around the wire to prevent tearing.

:The wire guides that feed the flippers are especially important to have their angle adjusted correctly. You want to avoid a hop as the ball transitions from wire to flipper bat. You can put a very slight bend in the wire's vertical orientation to tweak this transition. The best way to bend it is to remove it from the game and bend it slightly with pliers; do not try to tweak this in the game as it puts undue stress on the mounting hole.

:Another type of lane guide is a flat steel type guide used in an orbit or passageway back to the top of the playfield. Not a lot to tweak here but check that the mounting plates are not cracked and the screw holes are tight. Some guides have some adjustment built into them to tweak their positions. (Whirlwind and Flash are two examples that have this type in their shooter lanes.) If you find you need to tweak the position of the lane, fill the old hole completely with a hardwood dowel and glue, position the guide appropriately, mark and drill a new mounting screw. You can also use a dremel or similar to grind out a slot making a normally non-adjustable guide adjustable. The left lane guide above the upper left flipper on Eight Ball Deluxe is an example of a guide that almost always needs tweaking to avoid flipper bounce action on a ball coming down the left guide, spoiling your cross-playfield shot aim.

:Some early Bally and Stern games have a plastic inlane guide that becomes malformed or has its tip broken off. You can cut a replacement piece out of clear lexan to replace these. Cut the replacement piece as if you were cutting the entire piece of plastic, and attach it underneath the existing plastic. Another trick for the plastic lane guides is to embed a small wire guide in the appropriate position underneath the plastic guide. This is not as seamless as the clear plastic method, but it does play very well and avoids any headaches mounting the double layer of plastic.

==Rubber? I hardly knew her!==
:There used to be only one type of rubber available for all pinball machines - a soft gum rubber that was off-white in color, but was very bouncy and gave good ball action. Today, most rubber is available in either stark white or black, and various colors. In general, black rubber plays harder (i.e. less bounce) than white rubber, but that's not always the case. You have to try rubber rings from different makers to see how they play. If you like a more controlled type of gameplay, the harder less bouncy rubber might be for you. If you like the randomness imparted to the ball by bouncier rubber use a different variety. The soft gum rubber if you can find it is incredibly bouncy, and because of the stickiness of the rubber will impart more spin to the ball, truly making it wild.

:Recently urethane rubbers have been developed and released that offer a slightly different feel, somewhere in the middle of the hard/soft varieties. This type of rubber was designed to be very long lasting. The variety of rubber types currently available will allow you as the arbiter of play to tune your machine to your liking.

:Whatever rubber you end up using, there is still some variety in sizing and mounting. You can change the way your game plays by changing the size of the rings used; go one size smaller and hard shots to that rubber will rebound harder accordingly. Fatter rubber on mini posts will make shots tighter and harder, but also allow for more nudging action. Changing the type of ring to a different type can affect vastly how the game plays - if you like more pop bumper action for instance off a rubber, you can change where the rubber mounts (i.e. which posts surrounding the pop) to have a larger expanse of rubber vs. not. Don't go so far as to add new posts in to accommodate the new rubber position, unless you're really sure that's what you want. Keep in mind if you go with tighter rubber you might have problems keeping the posts mounted in the playfield, and may have to move to a machine threaded screw instead if the tension is too high.

==Plungers==
:Never run a plunger without a rubber tip on it. (It will mushroom out very quickly necessitating filing or hacksaw cutoff of the tip.) The plunger itself should be centered with respect to the ball track, and forward enough so the tip holds the ball forward of the playfield lip. Sometimes plungers get bent because people lift the machine by the plunger; it is best to replace the plunger in these cases.

:The barrel spring on the outside of the plunger varies in length, new ones are generally too stiff for the plunger to sit at its optimal position. You can mash the new springs in a vise to shorten them a bit. Do not run a plunger without the proper springs installed as it will damage the escutcheon plate on the cabinet, either denting it in the case of metal ones, or cracking it in the case of plastic ones.

:There are screws holding the plunger's position in place, loosen slightly so you can slide the mechanism around to get the best positioning. Tighten each opposing side a little at a time so you don't cant the mechanism to one side or the other, and don't overtighten it as that will put dents in the wood of the cabinet.

:Make sure the spring you are using on the inside is the proper one for your game. Some games require a weak spring to allow skill shots to be made (Whirlwind and Twilight Zone are 2 examples). Some games need a very strong spring to launch the ball properly (Pinbot and Taxi). When replacing the inner spring, get rid of the weaker "C" clip that holds it on and replace with an "E" clip, which is stronger and easier to install/remove.

==Coil Sleeves==
:Older games used aluminum coil sleeves to guide the mechanism's plunger smoothly into the coil. The function of a coil sleeve is to reduce the distance between the solenoid coil bore and the mechanism plunger, resulting in more precise action. An upgrade that can be done to aluminum coil sleeves is to replace them with more modern nylon ones. Nylon has self-lubricating qualities that make it ideal for this usage. No lube should ever be used on any solenoid plunger. It will gum up over time and cause weak mechanism response and a nice mess for the next person to clean up. Any machine with lube used in the past on its plungers should have the mechanisms disassembled, its metal parts cleaned with brake cleaner or isopropyl alcohol, and reassembled with a new nylon sleeve cut to the proper length.

:To cut nylon coil sleeves to length use a junker plunger in the center and a pipe cutter (available at most hardware stores). Tighten the cutter a little at a time to ensure the smoothest finish possible on the coil sleeve; don't try and make the cut in one go as that will result in a rough edge to the sleeve. Smoother is always better in a mechanism employing solenoids and plungers. File off and dress any sharp metal edges on a plunger that could snag the coil sleeve as it moves in the solenoid. If a coil plunger is particularly mushroomed, replace it.

==Connectors and Soldering==
:Anytime an electrical part of a machine has intermittent operation suspect any connectors in its power chain. Any connector in a power chain at its best adds a minute amount of resistance to the power flow. Jones plugs' connectors can be cleaned and polished on the older EM machines; newer solid state machines you can try and polish the pins, but the best thing to do is replace or eliminate the connectors if you can and they are causing problems. A steel or brass wire bottle brush of the appropriate size works well to clean Jones plugs, and you can get a very fine nylon bottle brush to clean the female connectors. Don't use a metal brush to clean the female side unless you're sure to find and clean up any broken brush strands.

:Often on solid state boards the male header pins crack from usage fatigue. Make sure any wire management straps are being used to support the weight of the harness going into the cabinet instead of depending on the header pin to support all that weight. Resoldering the header pins will fix the cracking and while it's not strictly necessary to replace the header pins, it wouldn't hurt either. Tug on and inspect all connectors to ensure the wiring is crimped tightly into the pin. Any loose wires should have their pins replaced with new properly crimped pins. Do not use solder on a crimped pin connector; it changes the temper of the connector pin which allows oxygen to penetrate the wire bundle, allowing oxidation.

:If you have some microswitches that use a spade connector, consider removing the connector and soldering the wire directly to the lug. The spade connectors were used on the wiring harnesses at the factory to speed production, not for any reliability concerns. Any connector added to a circuit introduces an unnecessary possible failure point. Any trouble shooting involving a circuit with a connector should have its connectors inspected very carefully as a first step.

==Slingshots==
:Pull the sling plastic and rubber off the slingshots. Make sure the posts are tight to the playfield, filling any loose ones or changing them to machine threaded screws into T-nuts. It's very common for the sling rubber over time to pull the posts towards each other, and the sling plastic being depended upon to hold them apart. This is not desirable at all.

:Adjust the standup switches so that the blade that touches the rubber is barely touching it. You don't want the blade adding any tension to the sling rubber itself. The secondary switch should be as close as you can make it to the first, as long as both blades are parallel. This is a very critical adjustment to make as you have 2 switches acting together, and you want one activation, not multiples as the rubber bounces back. Replace the sling switches with new switches or replace just the blade if they have been bent and mangled from incorrect adjustments. It's easier but more expensive to replace the entire switch vs. getting the blade parts (blade parts alone are <$1.00, new switches anywhere from $2.75-$6.00 depending on bracket installed/not and vendor).

:The size of rubber you use on the sling makes a huge difference in how it performs. Tighter lets you get the slings more sensitive, but can also limit how much the sling can move. Too loose will cause myriad problems getting the switches adjusted correctly.

:Sometimes there are nails straddling the sling actuator arm; the purpose of these nails is threefold. First, they help support the sling plastic in the case of sagging, so it doesn't hit the actuator arm. Secondly, it prevents the sling rubber from pressing back really far causing a weak sling. (The switches should never activate that far back, either - this would make for a very unresponsive sling). Thirdly, they prevent a ball from working its way under the rubber and getting trapped in the triangle under the sling plastic.

:It is worthwhile to remove the sling arm and clean it really well, and to check for wear. Grasp the actuator arm and rock it slightly at a right angle to its normal activation arc to check for wear. You will usually see some lateral slop in a sling mechanism; if it's excessive power will be lost on activation. The only remedy is to replace it, or use a small nylon washer to hold it true. Use a small bit of teflon lube on the pivot point. As usual, wipe it on and off. If you can see it, it's too much.

:Make sure the sling arm is held tight to the playfield, filling and drilling as needed. If there is a scoring switch attached here, make sure there's a fiberboard spacer between the metal blade and the actuator. Adjusting the scoring switch can be problematic as there's a fine line between not scoring and scoring twice (as the switch blade bounces).

==Standup/stationary Targets==
:Remove the target and inspect well. You can clean grease off the target with a pencil eraser or novus 2. Some standups would benefit from having a piece of weatherstripping foam added if not already present. (Any standup that gets hit with lots of force needs a foam block). Early solid state Bally, Stern, and Gottlieb games can benefit from a switch capacitor being added to help their performance. The switch capacitor lengthens quick hits to the standup so the MPU board can read even a very fast switch closure.

:Make sure the mounting bracket isn't bent so the target leans backwards - this will cause airballs and broken plastics. If anything the target should be angled slightly forward to help prevent this. Some machines would benefit from a brace on the back of the target to minimize bending.

:Any standup with gold plated contact points should be inspected for filing - if the gold plating is breached or gone, replace the contact points. Make sure the target bracket is held onto the playfield securely, fill and drill any egged out mounting holes. Inspect the switch blades that make up the target and straighten out or replace any that are mangled.

==Ramps==
:Clean ramps really well to promote fast ball action. Dirt will accumulate on the ramp surfaces and eventually cause "ball trails" to appear. Ramp flaps at the junction of the ramp to the playfield should be adjusted so that as gentle an angle as possible between the ramp and the playfield is attained. Torquing down the ramp flap creates a "ski jump" type effect, robbing power and momentum from the ball. Often this angle is enough to prevent a ramp from being able to be made consistently and smoothly.

:Ramps that have a switch bracket near the beginning of the ramp may need some tweaking with washers (spacers) to present the least resistance to the ball traveling under them. Often you can tell a ramp is too tight to the playfield when the ball actually strikes the switch bracket after jumping off the ski-lift-like ramp flap. The goal in tweaking a ramp is to present the least amount of resistance to ball flow as possible.

:TOURNAMENT TIP: The difficulty of a machine can be easily adjusted by adding/removing various types of sizes of rubber rings, posts, or sleeves from ramp entrances. For example, a popular and safe tournament strategy for Earthshaker! is to continuously shoot the center ramp shot until 99 miles are achieved, then continue shooting for 200k a ramp. This is a very safe shot that returns to the flipper to allow another shot. There is a yellow post sleeve to the left of the ramp entrance; changing this sleeve to a thicker, wider rubber will make the center shot tighter, requiring more skill to employ this previously-safe strategy. The thicker rubber will add risk and randomness to the formerly safe shot.

=Common Flipper Problems=
A list of common flipper issues, and corrections, can be found [http://www.pinwiki.com/wiki/index.php?title=Common_Flipper_Troubleshooting here]
=Shipping=
==Shipping Backglasses==
* [http://bgresto.com/?page_id=777 BGResto.com backglass packing technique]
* [http://www.flippers.com/back4sal.html flippers.com backglass packing technique]

==Shipping Playfields==
===Self-packed method===
# Put pool noodles / pipe insulation around all the edges of the playfield.
# Shrink wrap the playfield
# Get 1" thick foam board insulation, cut it to size (leave a 1" gap around all sides), and sandwich the playfield.
# Pack some newspaper around the edges of the playfield and start shrink wrapping the foam board around the playfield. Stuff the edges with padding as you go.
# Put duct tape around the corners to help reinforce them.
# As a good measure, wrap two layers of bubble wrap around the whole thing.
# Get some large moving boxes or large flat corrigated cardboard. Wrap up the package, and make liberal use of packing tape. Or, find a bicycle shop and see if they have any bike boxes available.
# Reinforce the corners with duct tape.

That will probably be about $35-$45 to ship. Packing materials will be around $15-$20, plus $20 for a roll of 80 gauge shrink wrap (if you don't already have some).

===Shipper-packed method===
# Put pool noodles / pipe insulation around all the edges of the playfield.
# Shrink wrap the playfield
# Take the wrapped playfield to UPS/FedEx, etc for packing. They will wrap the playfield in multiple layers of bubble wrap, stuff the playfield in a giant box, and fill it with brown paper.

This option may cost around $60-$100. It's less effort than the self-packing method, however, there is a higher chance of damage without the foam board insulation protecting the playfield.

=Glass Sizes=
Note that the measurements below were compiled from various lists and individuals who provided measurements of pieces of glass from their games, so they might not be 100% accurate. All possible efforts have been made to try to ensure that the correct measurements have been posted. If it is discovered that a measurement is incorrect or if a new entry needs to be added, please correct/add it below or [https://pinside.com/pinball/forum/topic/playfield-glass-sizes-backglass-sizes-request-for-measurements post in the glass size thread on pinside]

==Playfield Glass Sizes==
===EM===
{| class="wikitable"
!Manufacturer
!System
!Game Style
!Glass Dimensions
!Notes
|-
|Bally
|1970s
|Standard
|21" x 43" x 3/16"
|Games that used a canopy around the glass had a smaller glass
|-
|Bally
|Late 1960s-Early 1970s
|Standard
|21" x 41-1/2" x 3/16"
|Games that use a metal canopy frame
|-
|Chicago Coin
|
|Standard
|?
|
|-
|Gottlieb
|1970s
|Standard
|21" x 43" x 3/16"
|
|-
|Williams
|Late 1940s-1950s
|Standard
|21" x 41" x 3/16"
|Early flipper games
|-
|Williams
|1960-1961 (with front shelf)
|Standard
|21-3/4" x 43" x 3/16"
|Games with a shelf on the front of the cabinet where slightly wider than most standard body games: Black Jack, Bo Bo, Caravelle, Darts, Highways, Hollywood, Jungle, Magic Clock, Music Man, Viking
|-
|Williams
|1970s
|Standard
|21" x 43" x 3/16"
|
|}

====Exceptions====
{| class="wikitable"
!Manufacturer
!Title
!Game Style
!Glass Dimensions
!Notes
|-
|Chicago Coin
|Thing
|Pinball
|21-3/16" x 50" x 3/16"
|
|-
|Chicago Coin
|Play Ball
|Pinball
|Possibly same size as Thing
|Has artwork inked on underside of glass
|-
|Williams
|Upper Deck
|Pitch 'N Bat
|23" x 38-13/16" x 3/16"
|
|-
|}

===Early Solid State===
{| class="wikitable"
!Manufacturer
!System
!Game Style
!Glass Dimensions
!Notes
|-
|Allied Leisure
|Gen1, Gen2
|Standard
|21" x 43" x 3/16"
|
|-
|Atari
|Gen1, Gen2
|Widebody
|27-3/4" x 45-1/2" x 3/16"
|See Exceptions
|-
|Bally
| -17, -35, -133, 6803
|Standard
|21" x 43" x 3/16"
|See Exceptions
|-
|Bally
| -35
|Widebody
|27-1/2" x 43" x 3/16"
|Embryon, Future Spa, Hotdoggin', Paragon, Space Invaders
|-
|Game Plan
|MPU-2
|Standard
|21" x 43" x 3/16"
|
|-
|Gottlieb
|System 1
|Standard
|21" x 43" x 3/16"
|
|-
|Gottlieb
|System 1
|Ultra Widebody
|27-5/8" x 48-7/16" x 3/16"
|Genie, Roller Disco
|-
|Gottlieb
|System 80, 80A
|Widebody
|24-5/8" x 48-3/8" x 3/16"
|Black Hole, Counterforce, Eclipse, Force II, Haunted House, James Bond 007, Panthera, Pink Panther, Spider-Man, Time Line, Volcano, Devil's Dare, Punk!, Q*Bert's Quest, Striker
|-
|Gottlieb
|System 80
|Ultra Widebody
|27-5/8" x 48-3/8" x 3/16"
|Circus, Star Race
|-
|Gottlieb
|System 80A, 80B
|Standard
|21" x 43" x 3/16"
|
|-
|Stern
|MPU-100, MPU-200
|Standard
|21" x 43" x 3/16"
|
|-
|Stern
|MPU-200
|Widebody
|24-9/16" x 45-3/4" x 3/16"
|Big Game, Cheetah, Flight 2000, Freefall, Iron Madien, Split Second, Viper. Also: see exceptions.
|-
|Williams
|System 3-11
|Standard
|21" x 43" x 3/16"
|
|-
|Williams
|System 3-11
|Widebody
|27-5/8" x 43" x 3/16"
|Algar, Contact, Laser Ball, Pokerino, Scorpion, Stellar Wars
|-
|Zaccaria
|
|Standard
|21" x 43" x 3/16"
|
|-
|}

====Exceptions====
{| class="wikitable"
!Manufacturer
!Title
!Game Style
!Glass Dimensions
!Notes
|-
|Alvin G
|USA Football, A.G. Football, A.G. Soccer-Ball, Dinosaur Eggs
|Head-to-Head
|21" x 53-1/8" x 3/16"
|
|-
|Atari
|Hercules
|
|39-3/8" x 74-1/8" x 1/4"
|
|-
|Bally
|Baby Pacman
|Hybrid
|21" x 16-1/8" x 3/16"
|
|-
|Bally
|Granny and the Gators
|Hybrid
|20-15/16" x 24-5/16" x 3/16"
|
|-
|Bally
|Escape From The Lost World
|Standard
|(Same as Standard)
|The playfield glass has artwork screen printed directly onto the glass.
|-
|Bally
|Rapid Fire
|Standard
|21" x 37" x 3/16"
|
|-
|Gottlieb
|Caveman
|Widebody
|24-5/8" x 43-1/8" x 3/16"
|This glass is shorter because of the large control panel over top of the apron.
|-
|Stern
|Orbitor 1
|Widebody
|24-5/8" x 45-3/4" x 3/16"
|
|-
|Williams
|Hyperball
|Standard
|21" x 37" x 3/16"
|
|-
|Williams
|Joust
|Head-to-Head
|25-1/2" x 42-1/2" x 3/16"
|
|-
|}

===Modern===
{| class="wikitable"
!Manufacturer
!System
!Game Style
!Glass Dimensions
!Notes
|-
|Alvin G
|
|Standard
|21" x 43" x 3/16"
|
|-
|Capcom
|
|Standard
|21" x 43" x 3/16"
|
|-
|Data East
|
|Standard
|21" x 43" x 3/16"
|
|-
|Data East
|
|Widebody
|23-3/4" x 43" x 3/16"
|Guns 'N Roses, WWF Royal Rumble. Note: measurements were incorrect in original manuals, but corrected in [[Media:sb99.pdf|service bulletin 99]].
|-
|Gottlieb
|System 3
|Standard
|21" x 43" x 3/16"
|
|-
|Jersey Jack Pinball
|
|Standard
|21" x 43" x 3/16"
|Dialed In, Willy Wonka
|-
|Jersey Jack Pinball
|
|Widebody
|23-3/4" x 43" x 3/16"
|Wizard of Oz, The Hobbit, Pirates of the Caribbean
|-
|Sega/Stern
|Whitestar, SAM
|Standard
|21" x 43" x 3/16"
|
|-
|Sega
|Whitestar
|Widebody
|23-3/4" x 43" x 3/16"
|Batman Forever; Same size as Williams WPC SuperPin
|-
|Stern
|Spike
|Standard
|21" x 43" x 3/16"
|
|-
|Williams
|WPC
|Standard
|21" x 43" x 3/16"
|See Exceptions
|-
|Bally/Williams
|WPC
|SuperPin
|23-3/4" x 43" x 3/16"
|Demolition Man, Indiana Jones: The Pinball Adventure, Popeye Saves the Earth, Red & Ted's Road Show, Star Trek: The Next Generation, Twilight Zone
|-
|Williams
|Pin2000
|Pin2000
|20.50" x 43"?/41.5"? x ?
|Special half-mirrored glass
|-
|}

====Exceptions====
{| class="wikitable"
!Manufacturer
!Title
!Game Style
!Glass Dimensions
!Notes
|-
|Gottlieb
|Super Mario Bros. Mushroom World
|Mini
|21" x 32" x 3/16"
|
|-
|Williams
|Banzai Run
|
|
|Two glasses
|-
|Williams
|Safe Cracker
|Standard
|18.5" x 36-1/2" x 3/16"
|
|-
|Williams
|Slugfest
|Pitch & Bat
|23" x 35-1/4" x 3/16"
|
|-
|Williams
|Ticket Tack Toe
|Standard
|18-1/2" x 36-1/2" x 3/16"
|
|-
|Williams
|Varkon
|Arcade Cabinet
|24-7/16" x 21" x 3/16"
|
|-

|}

==Backglass Sizes==
Backglass sizes for translites
{| class="wikitable"
!Manufacturer
!System
!Game Style
!Glass Dimensions
!Notes
|-
|Bally
|6803
|Standard
|26-1/4" x 24-5/8" x 1/8"
|Games such as City Slicker, Escape from the Lost World. Note: the original artwork was a printed backglass on some titles. Additionally, reproduction translites were produced for some of these titles, such as Strange Science.
|-
|Bally
|6803
|Standard
|27" x 23-1/2" x 1/8"
|Atlantis, Truck Stop (both games have speaker bar on the top of the backbox)
|-
|Bally
|System 11
|Standard
|27" x 23-1/2" x 1/8"
|Games with the Bally logo and speakers at the top of the backbox. The Bally Game Show, Bugs Bunny's Birthday Ball, Dr. Dude, Elvira and the Party Monsters, Pool Sharks, Mousin Around, Radical, Transporter the Rescue
|-
|Capcom
|
|Standard
|26" x 19-5/8" x 1/8"
|Needs to be verified.
|-
|Data East
|
|Standard
|22-1/2" x 26" x 1/8"
|Games with a 128x32 DMD
|-
|Data East
|
|Standard
|23" x 26" x 1/8"
|Games with a 128x16 DMD
|-
|Data East
|
|Widebody
|22-3/8" x 26" x 1/8"
|Guns 'N Roses, WWF Royal Rumble. NOTE: This measurement needs to be confirmed.
|-
|Gottlieb
|System 80B
|Standard w/ Speaker Panel
|25" x 20" x 1/8"
|Side Trim - # 24990 Top Trim - # 24991 Lift Trim - # 24964
|-
|Gottlieb
|System 80B
|Standard w/ Metal Speaker Grill above Translite
|24" x 25" x 1/8" (assumed)
|Please verify - games like Bad Girls, Hot Shots, Bone Busters, etc.
|-
|Gottlieb
|System 80B
|Standard w/ Score Displays Above Translite
|?
|Please verify - games including Diamond Lady, TX-Sector, and Robo-War
|-
|Gottlieb
|System 3 (Alphanumeric)
|Standard
|24" x 25" x 1/8"
|Games like Lights Camera Action!, Title Fight, Silver Slugger, Surf N' Safari, etc. Side Trim - # 26086 Top Trim - # 24991 Lift Trim - # 24964
|-
|Gottlieb
|System 3 (Dot Matrix)
|Standard
|25" x 20" x 1/8"
|
|-
|Sega
|DataEast/Sega Version 3b & Whitestar
|Standard/Widebody
|26-3/8" x 19-11/16" x 1/8"
|Games using the 192x64 DMD. (Note: the measurement is from the Baywatch translite; actual glass measurement needs to be verified). Apollo 13, Batman Forever, Baywatch, Frankenstein
|-
|Sega
|Whitestar
|Standard
|?
|(Games assumed to be the same size, but unverified). Goldeneye, Independence Day, Twister.
|-
|Sega
|Whitestar
|Curved/Convex
|?
|Convex/curved lexan front and back showcase set: Part #545-5743-00 & #545-5753-00. The Lost World Jurassic Park, Space Jam, Star Wars Trilogy, Starship Troopers, Viper Night Drivin', X-Files
|-
|Sega
|Standard
|Whitestar
|?
|(Note: games that followed the curved displays have a different style backbox and the measurement may be different than the games preceding the curved displays). Godzilla, Golden Cue, Lost in Space.
|-
|Sega
|Whitestar
|Standard
|26" x 19-1/4" x 1/8"
|(Note: the games that followed the curved displays and were transition games into Stern have a different style backbox and the measurement may be different than the games preceding the curved displays; Harley Davidson is unverified). Harley Davidson, South Park
|-
|Stern
|Whitestar
|Standard
|26" x 19-1/4" x 1/8"
|Austin Powers, Avatar, Avatar Limited Edition, Batman, Big Buck Hunter, Csi, Dale Jr, Elvis, Family Guy, Game Of Thrones Limited Edition, Game Of Thrones Premium, Game Of Thrones Pro, Grand Prix, Harley Davidson 3rd Edition, Indiana Jones, Iron Man, Iron Man Pro, Kiss Pro, Lord Of The Rings, Nascar, NBA, NFL, Pirates Of The Caribbean, Ripley's Believe It Or Not, Roller Coaster Tycoon, Sharkey's Shootout, Shrek, Simpsons Pinball Party, Sopranos, Spiderman, Spiderman Vault Edition, Terminator 3, Tron, Wheel Of Fortune, World Poker Tour
|-
|-
|Stern
|SAM
|Standard
|?
|
|-
|-
|Stern
|SAM
|Standard
|?
|Games with "tilted" speaker panel starting with Star Trek
|-
|Stern
|Spike
|Standard
|?
|Spike games with a DMD display
|-
|Stern
|Spike 2
|Standard
|25-7/8" x 16-1/2" x 1/8"
|Spike games with an LCD display
|-
|Williams
|System 11
|Standard
|27" x 19" x 1/8"
|See Exceptions
|-
|Williams
|WPC
|Standard
|27" x 18-7/8" x 1/8" (685x479x3mm)
|See Exceptions
|-
|Williams
|WPC
|SuperPin
|27" x 18-7/8" x 1/8"
|Demolition Man, Indiana Jones: The Pinball Adventure, Popeye Saves the Earth, Red & Ted's Road Show, Star Trek: The Next Generation, Twilight Zone
|-
|Williams
|Pin2000
|Pin2000
|22" x 14-1/4" x 1/8"
|Marquee (made of plexiglass, rather than actual glass)
|-
|}

===Exceptions===
{| class="wikitable"
!Manufacturer
!Title
!Game Style
!Glass Dimensions
!Notes
|-
|Williams
|Big Guns (Sys11)
|Standard
|27" X 25-1/4" x 1/8"
|This backglass is taller than most other standard backglasses
|-
|Williams
|Pinbot (Sys11)
|Standard
|28-1/2" X 21" x 1/8"
|Due to a possible margin of error with measuring, 28-7/16" x 21" x 1/8" may also be a possible measurement.
|-
|Williams
|Safe Cracker (WPC)
|Standard
|19-1/2" X 18-7/8" x 1/8"
|
|-
|Williams
|Slugfest (WPC)
|Pitch & Bat
|7-3/8" X 22-7/16" X 3/16"
|Glass in front of dot matrix display
|-
|}

Williams WPC

2022-08-23T12:04:47Z

Jimpal: /* Trough Divots */

Click to go back to the [[Williams_Repair_Guides | Williams solid state repair guides index]].

==Introduction==
This guide covers Williams WPC (sometimes called WPC-89), WPC-S, and WPC-95 games.

==Game List==
===WPC (WPC-089) CPU===
====WPC (Alphanumeric)====
*[[Funhouse]]
*[[Harley-Davidson]]
*[[The Machine: Bride of Pin*Bot]]

====WPC (Dot Matrix)====
*[[Gilligan's Island]]
*[[Terminator 2: Judgement Day]]
*[[Hurricane]]
*[[Party Zone]]

====WPC FlipTronics I & II====
*[[The Addams Family]] / Addams Family Gold (the only Fliptronics I games)
*[[The Getaway: High Speed II]]
*[[Black Rose]]
*[[Fish Tales]]
*[[Doctor Who]]
*[[Creature from the Black Lagoon]]
*[[White Water]]
*[[Bram Stoker's Dracula]]
*[[Twilight Zone]]

====WPC DCS Sound====
*[[Indiana Jones: The Pinball Adventure]]
*[[Judge Dredd]]
*[[Star Trek: The Next Generation]]
*[[Popeye Saves The Earth]]
*[[Demolition Man]]

===WPC-S with DCS Sound===
*[[World Cup Soccer]]
*[[The Flintstones]]
*[[Corvette]]
*[[Red & Ted Road Show]]
*[[The Shadow]]
*[[Dirty Harry]]
*[[Theatre of Magic]]
*[[No Fear: Dangerous Sports]]
*[[Indianapolis 500]]
*[[Johnny Mnemonic]]
*[[Jack*Bot]]
*[[WHO Dunnit]]

===WPC-95 CPU===
*[[Congo]]
*[[Attack from Mars]]
*[[Safecracker|Safe Cracker]]
*[[Tales of the Arabian Nights]]
*[[Scared Stiff]]
*[[Junk Yard]]
*[[NBA Fastbreak]]
*[[Medieval Madness]]
*[[Cirqus Voltaire]]
*[[No Good Gofers]]
*[[The Championship Pub|The Champion Pub]]
*[[Monster Bash]]
*[[Cactus Canyon]]

==Game List Chart==

===WPC-89 & WPC-S===

{| class="wikitable sortable"
|-
!Game
!WPC System
!MPU
!Driver Board
!Display Driver
!Display
!Sound
!Flipper
!Transformer
!Additional Boards
!Notes

|-
|[[Dr. Dude]]
|WPC-89 Alphanumeric / System 11
|WPC-89 (A-12742)
|A-12697-1
|A-12739-1
|Alphanumeric, dual display (A-12793)
|D-11581-2016 with a special power supply board (A-13502)
|N/A
|5610-12718-00 (WPC) or 5610-12136-00 (System 11)?
|Sound overlay board (A-13502)
|Only about 100 Dr. Dude sample games use the WPC boardset. They included a special power supply board (A-13502) to accommodate the System 11 sound board (D-11581), and also includes the System 11 interconnect board (D-12313-2016). The bulk of the production run used the [[Williams System 9 - 11|System 11C boardset]].
|-

|-
|[[Funhouse]]
|WPC-89 Alphanumeric
|WPC-89 (A-12742)
|A-12697-1
|A-12739-1
|Alphanumeric, dual display (A-12793)
|A-12738-50003
|N/A
|5610-12718-00
|
|Early FH games had a System 11 sound board (D-11581 / A-13971) with a special power supply board (A-13502) and a 5610-12425-00 transformer. Later games used the WPC A-12738 sound board. [[media: Williams_1990_Funhouse_Prototype_Manual_Addendum.pdf|Funhouse Manual Addendum]]
|-

|[[Harley-Davidson]]
|WPC-89 Alphanumeric
|WPC-89 (A-12742)
|A-12697-1
|A-12739-1
|Alphanumeric, single display (A-12794)
|A-12738-20001
|N/A
|5610-12718-00
|
|
|-

|[[The Machine: Bride of Pin*Bot]]
|WPC-89 Alphanumeric
|WPC-89 (A-12742)
|A-12697-1
|A-12739-1
|Alphanumeric, dual display (A-12793)
|A-12738-50002
|N/A
|5610-12718-00
|
|
|-

|[[Slugfest]]
|WPC-89 Dot Matrix
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-60001
|N/A
|5610-12835-00
|
|Pitch & Bat game.
|-

|[[Gilligan's Island]]
|WPC-89 Dot Matrix
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20003
|N/A
|5610-12835-00
|
|
|-

|[[Terminator 2: Judgement Day]]
|WPC-89 Dot Matrix
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50013
|N/A
|5610-12835-00
|
|
|-

|[[Hurricane]]
|WPC-89 Dot Matrix
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50012
|N/A
|5610-12835-00
|
|
|-

|[[Party Zone]]
|WPC-89 Dot Matrix / WPC-89 Fliptronic I
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20004
|N/A
|5610-12835-00
|
|Some later PZ games started transitioning over to use the Fliptronic I board (A-15028). Different game ROMs are used depending upon if the PZ uses solid state flippers or fliptronic/standard flippers.
|-

|[[Hot Shot]]
|WPC-89 Dot Matrix
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50017
|N/A
|5610-12835-00
|
|Redemption game.
|-

|[[The Addams Family]]
|WPC-89 Fliptronic I
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20017
|A-15028
|5610-12835-00
|Extra flipper power supply (A-15416)
|
|-

|[[The Getaway: High Speed II]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50004
|A-15472
|5610-12835-00
|
|
|-

|[[Black Rose]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20013
|A-15472
|5610-12835-00
|
|
|-

|[[Doctor Who]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20006
|A-15472
|5610-12835-00
|
|
|-

|[[Fish Tales]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50005
|A-15472
|5610-12835-00
|
|
|-

|[[Creature from the Black Lagoon]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-20018
|A-15472
|5610-12835-00
|
|
|-

|[[White Water]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50018
|A-15472
|5610-12835-00
|
|
|-

|[[Bram Stoker's Dracula]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-12738-50001
|A-15472
|5610-12835-00
|
|
|-

|[[Twilight Zone]]
|WPC-89 Fliptronic II
|WPC-89 (A-12742)
|A-12697-1 or A-12697-3
|A-14039
|DMD
|A-12738-50020
|A-15472
|5610-12835-00
|Auxiliary 8-Driver PCB (A-16100)
|Mid-way through TZ's production run, the A-12697-1 driver board starting being replaced with A-12697-3. At some point during production, a coin door interlock switch was added in order to cut high voltage 20VDC/50VDC power as a safety measure when the coin door was opened; this was included in all WPC titles from this point forward.
|-

|[[Indiana Jones: The Pinball Adventure]]
|WPC-DCS
|WPC-89 (A-12742)
|A-12697-3
|A-14039
|DMD
|A-16917-50017
|A-15472-1
|5610-13491-00
|Auxiliary 8-Driver PCB (A-16100)
|
|-

|[[Judge Dredd]]
|WPC-DCS
|WPC-89 (A-12742)
|A-12697-3
|A-14039
|DMD
|A-16917-20020
|A-15472-1
|5610-13491-00
|
|
|-

|[[Star Trek: The Next Generation]]
|WPC-DCS
|WPC-89 (A-12742)
|A-12697-1
|A-14039
|DMD
|A-16917-50023
|A-15472-1
|5610-13491-00
|Auxiliary 8-Driver PCB (A-16100)
|Driver board was changed to A-12697-1.
|-

|[[Demolition Man]]
|WPC-DCS
|WPC-89 (A-12742)
|A-12697-3
|A-14039
|DMD
|A-16917-50028
|A-15472-1
|5610-13953-00
|Auxiliary 8-Driver PCB (A-16100)
|A few prototype games used a WPC-S MPU, which uses a different ROM in order to work with the WPC-S security PIC. The standard ROM for WPC-89 boards will not work on the WPC-S board, but a WPC-89 MPU can be swapped in to replace the WPC-S MPU. All the sample and production games used a WPC-89 MPU.
|-

|[[Popeye Saves The Earth]]
|WPC-DCS
|WPC-89 (A-12742)
|A-12697-3
|A-14039
|DMD
|A-16917-50022
|A-15472-1
|5610-13491-00
|
|
|-

|[[World Cup Soccer]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039
|DMD
|A-16917-50031
|A-15472-1
|5610-13953-00
|
|
|-

|[[The Flintstones]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50029
|A-15472-1
|5610-13953-00
|
|Some revisions were made on the A-14039.1 DMD driver board, but it is interchangeable with A-14039.
|-

|[[Corvette]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50036
|A-15472-1
|5610-13953-00
|Auxiliary 8-Driver PCB (A-16100)
|
|-

|[[Red & Ted Road Show|Red & Ted's Road Show]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50024
|A-15472-1
|5610-13953-00
|Auxiliary 8-Driver PCB (A-16100)
|The transformer was moved to the rear of the cabinet starting with this game.
|-

|[[The Shadow]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50032
|A-15472-1
|5610-13953-00
|
|
|-

|[[Dirty Harry]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50030
|A-15472-1
|5610-13953-00
|
|
|-

|[[Theatre of Magic]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50039
|A-15472-1
|5610-14515-00
|
|
|-

|[[No Fear: Dangerous Sports]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50025
|A-15472-1
|5610-14515-00
|
|
|-

|[[Indianapolis 500]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50026
|A-15472-1
|5610-14515-00
|
|
|-

|[[Johnny Mnemonic]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50042
|A-15472-1
|5610-14515-00
|
|
|-

|[[WHO Dunnit]]
|WPC-S
|WPC-S (A-17651)
|A-12697-4
|A-14039.1
|DMD
|A-16917-50044
|A-15472-1
|5610-14515-00
|
|This was the only game to use a A-12697-4 driver board.
|-

|[[Jack*Bot]]
|WPC-S
|WPC-S (A-17651)
|A-12697-3
|A-14039.1
|DMD
|A-16917-50051
|A-15472-1
|5610-14515-00
|
|
|-
|}

===WPC-95===

{| class="wikitable sortable"
|-
!Game
!WPC System
!MPU
!Driver Board
!AV Board
!Display
!Transformer
!Additional Boards
!Notes
|-

|[[Congo]]
|WPC-95
|WPC-95 (A-20119)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|The first WPC-95 game. The A-20516 AV Board drives both sound and the DMD. The A-20028 driver board included flipper power circuits, eliminating the need for a separate fliptronic board.
|-

|[[Attack from Mars]]
|WPC-95
|WPC-95 (A-20119)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[safecracker|Safe Cracker]]
|WPC-95
|WPC-95 (A-20119)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[Ticket Tac Toe]]
|WPC-95
|WPC-95 (A-20119)
|A-20028
|A-20516
|DMD
|?
|
|Redemption game (with flippers).
|-

|[[Tales of the Arabian Nights]]
|WPC-95
|WPC-95 (A-20119)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[Scared Stiff]]
|WPC-95
|WPC-95 (A-20119 or A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|The first appearance of a revision to the MPU. A-20119 and A-21377 can be used interchangeably in any WPC-95 games.
|-

|[[Junk Yard]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[NBA Fastbreak]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-01
|
|
|-

|[[Medieval Madness]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-01
|
|
|-

|[[Cirqus Voltaire]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|DMD is mounted on the playfield, rather than in the backbox.
|-

|[[No Good Gofers]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[The Championship Pub|The Champion Pub]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-00
|
|
|-

|[[Monster Bash]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-01
|
|
|-

|[[Cactus Canyon]]
|WPC-95
|WPC-95 (A-21377)
|A-20028
|A-20516
|DMD
|5610-14515-01
|
|
|-

|}

==Recommended Documentation==
===Manuals & Schematics===
Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids. The owner's game manual is a handy resource to have for general game operation, game settings & diagnostics, switch & lamp matrices, fuse lists, circuit boards and parts, playfield assemblies, some basic schematics, and wiring diagrams.

Be aware that although rare, some factory documentation contains errors in schematics, wiring, switch/lamp matrices, and solenoid assignments.

Some games have information split between two manuals: a game manual (for general game operation) and an operations guide (for more technical information).

{| class="wikitable"
|-
!Guide
!Version
!Cover
!Source
!Notes

|-
|Pinball Safety Manual
|16-10371, January 1, 1997
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Manual contains multiple languages.

|}

===Theory of Operation & Schematics===
Details for board and cabinet schematics and theory of operation guides for WPC games can be found in separate documents. There are several versions of each generation. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball].

{| class="wikitable"
|-
!Guide
!Version
!Cover
!Source
!Notes

|-
|WPC Theory of Operation and Schematics Manual
|16-9289, October 1991
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/djtz/ Viewer for Guide] [https://online.fliphtml5.com/vrtyz/pgds/ Viewer for Schematics]
|

|-
|WPC Schematic Manual
|16-9473 (undated)
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Switch row 7 & 8 are reversed from what is printed. Row 7 should be pin 5 of U19, and row 8 should be pin 7 of U19.

|-
|WPC Schematic Manual
|16-9473-1, May 17, 1993
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/wrhm/ Viewer] [http://howtopinball.com/files/pinball/paperwork/williams/wpc/Williams-WPC-Schematics_16-9473-1.pdf PDF]
|Switch row 7 & 8 are reversed from what is printed. Row 7 should be pin 5 of U19, and row 8 should be pin 7 of U19.

|-
|WPC Schematic Manual
|16-9473-2, April 25, 1994
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Switch row 7 & 8 are reversed from what is printed. Row 7 should be pin 5 of U19, and row 8 should be pin 7 of U19.

|-
|WPC Schematic Manual
|16-9834, June 1994
|[[file:placeholder.jpg|thumb|left|140px]]
|
|

|-
|WPC Schematic Manual
|16-9834.2, January 1995
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/fsgs/ Viewer]
|

|-
|WPC-S (Security) Schematic Manual
|
|[[file:placeholder.jpg|thumb|left|140px]]
|
|

|-
|WPC-95 Schematic Manual
|16-10159.2, March 1996
|[[file:placeholder.jpg|thumb|left|140px]]
|
|

|-
|WPC-95 Schematic Manual
|16-10159.3, July 1997
|[[file:placeholder.jpg|thumb|left|140px]]
|[http://howtopinball.com/files/pinball/paperwork/williams/wpc/Williams-WPC-95-Schematics-Manual_16-10159.3.pdf PDF]
|

|}

===Parts Catalogs===
Parts catalogs can also be useful, which include part numbers (helpful for purchasing parts online), exploded views of assemblies (helpful to see how the assemblies are put together), and board layouts & parts lists, and diagrams for controlled lamp, solenoid, and rubber locations. Parts catalogs also had supplementary updates to add and replace pages as newer games were released after the initial release of the catalogs.

Online copies of Bally & Williams parts catalogs can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball].

{| class="wikitable"
|-
!Manufacturer
!Catalog
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Blue Parts Catalog (1984-1987)
|16-9064
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Comet, F-14 Tomcat, Grand Lizard, High Speed, Millionaire, Pin Bot, Road Kings, Sorcerer, Space Shuttle
|This was an early version of the blue parts catalog, and only included 9 pinball titles (and 3 shuffle alley titles). The pages of this catalog were printed on white paper. Additional titles were later included in a "parts catalog supplement" packet (16-9064-A) with blue-colored pages, which added and replaced pages for this earlier version of the parts catalog.

|-
|Williams
|Blue Parts Catalog (Supplementary Catalog) (1987-1988)
|16-9064-A
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Banzai Run, Big Guns, Cyclone, Fire!, Space Station, Swords of Fury, Taxi
|This "parts catalog supplement" packet with blue-colored pages added and replaced pages for the earlier version of the parts catalog. It included 7 new pinball titles not included in the previous version of the parts catalog. Later catalogs had these new pages included and were not colored blue.

|-
|Williams
|Blue Parts Catalog (1984-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer]
|Banzai Run, Big Guns, Black Knight: 2000, Comet, Cyclone, Earthshaker!, F-14 Tomcat, Fire!, Grand Lizard, High Speed, Jokerz!, Millionaire, Pin Bot, Police Force, Road Kings, Sorcerer, Space Shuttle, Space Station, Swords of Fury, Taxi
|This is the latest version of the blue parts catalog. It included the game titles in the previous version, information from the supplementary parts catalog, a few new pinball titles, and a total of 5 shuffle alley titles. The blue parts catalog came in a blue-colored binder with the catalog's cover and game titles printed on the front, and basic information printed on the spine. The pages of this catalog were printed on pink paper.

|-
|Williams
|Red Parts Catalog (1989-1990)
|16-9190
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Bad Cats, Diner, Rollergames, Whirlwind
|The red parts catalog came in a red-colored binder with some basic information printed on the cover and spine. This version of the parts catalog included 4 pinball titles and 2 shuffle alley titles. The pages were printed on white-colored paper.

|-
|Williams
|Red Parts Catalog
|16-9190-A
|[[file:placeholder.jpg|thumb|left|140px]]
|
|?
|The red parts catalog came in a red-colored binder with some basic information printed on the cover and spine. This was a supplementary parts catalog that updated pages and added titles to the previous version of the red parts catalog. The pages were printed on blue-colored paper.

|-
|Williams
|Red Parts Catalog (Supplementary Catalog) (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine: Bride of Pin Bot, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|The red parts catalog came in a red-colored binder with some basic information printed on the cover and spine. This version of the parts catalog included 13 pinball titles, and 5 shuffle alley titles, 7 video came titles, and 3 novelty game titles. The pages were printed on gray-colored paper.

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1990)
|16-9147
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Atlantis, Elvira, Game Show, Mousin' Around, Transporter, Truck Stop
|The yellow parts catalog came in a yellow-colored binder with some basic information printed on the cover and spine. The pages were printed on white-colored paper.

|-
|Bally/Midway
|Yellow Parts Catalog (Supplementary Catalog) (1988-1991)
|16-9147-A
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Atlantis, Bugs Bunny, Dr. Dude, Elvira, Game Show, Harley Davidson, Mousin' Around, Pool Sharks, Radical!, Transporter, Truck Stop
|The yellow parts catalog came in a yellow-colored binder with some basic information printed on the cover and spine. This was a supplementary update to the previous version of the catalog, which included 11 pinball titles and 4 video game titles. The pages were printed on yellow-colored paper.

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer]
|Addams Family, Atlantis, Black Rose, Bugs Bunny, Dr. Dude, Dr. Who, Elvira, Game Show, Gilligan's Island, Harley Davidson, Mousin' Around, Party Zone, Pool Sharks, Radical!, Transporter, Truck Stop
|The yellow parts catalog came in a yellow-colored binder with some basic information printed on the cover and spine. The pages were printed on gold-colored paper.

|-
|Bally/Midway
|Gray Parts Catalog (1992-1994)
|16-9562
|[[file:placeholder.jpg|thumb|left|140px]]
|
|Creature From the Black Lagoon, Judge Dredd, Popeye Saves the Earth, Twilight Zone
|The gray parts catalog came in a white-colored binder with gray colored paper inserts for the spine and cover that included the company name, parts catalog, and part number. The pages were printed on white-colored paper.
|-
|Bally/Midway
|Gray Parts Catalog (Supplementary Catalog) (1992-1995)
|16-9562-A
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/ckao/ Viewer]
|Addams Family Gold, Corvette, Creature From the Black Lagoon, Indianapolis 500, Judge Dredd, Popeye Saves the Earth, The Shadow, Theatre Of Magic, Twilight Zone, Who Dunnit, World Cup Soccer
|The gray parts catalog came in a white-colored binder with gray colored paper inserts for the spine and cover that included the company name, parts catalog, and part number. This was a supplementary update to the previous version of the catalog. The pages were printed on light blue colored paper.

|-
|Williams
|Green Parts Catalog (1993-1995)
|16-9932
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/foky/ Viewer]
|Demolition Man, Dirty Harry, Demolition Man, Indiana Jones, Road Show, Star Trek - Next Generation
|The green parts catalog came in a white-colored binder with green colored paper inserts for the spine and cover that included the company name, parts catalog, and part number. There was no supplementary update to this catalog.

|-
|Williams
|Genuine Replacement Parts Catalog (1997-1998)
|10/97
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/yjjv/ Viewer]
|
|This catalog mainly provides listings, parts numbers, and drawings of commonly replaceable generic pinball parts for Bally/Williams games, such as flipper assembly parts, target parts, posts, springs, connectors, coils, plungers, etc. It does not contain any game-specific information.

|}

===Service Bulletins===
Supplementary service bulletin books were released, which included service bulletins that detailed any problems or issues with games that were discovered after they were released.

{| class="wikitable"
|-
!Manufacturer
!Catalog
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1991.pdf PDF]
|Funhouse, Gilligan's Island, Harley Davidson, Slugfest, Terminator 2
|This book includes some System 11 games.

|-
|Williams
|Service Bulletin Book, 1992
|[[file:Williams-1992-service-bulletin-book-cover.jpg|thumb|left|140px]]
|[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1992.pdf PDF]
|Addams Family, Funhouse, Hurricane, Party Zone, Terminator 2
|

|-
|Williams
|Service Bulletin Book, Fall 1992
|[[file:Williams-1992-fall-service-bulletin-book-cover.png|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1992-fall.pdf PDF]
|Addams Family, The Getaway, Strike Master (shuffle alley)
|

|-
|Williams
|Service Bulletin Book, 1993
|[[file:Williams-1993-service-bulletin-book-cover.jpg|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1993.pdf PDF]
|Black Rose, Creature From the Black Lagoon, Doctor Who, Dracula, Fish Tales, NBA Jam, White Water
|

|-
|Williams
|Service Bulletin Book, 1994
|[[file:Williams-service-bulletin-book-1994-cover.jpg|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1994.pdf PDF]
|Dracula, Indiana Jones, Judge Dredd, Star Trek the Next Generaton, Twilight Zone
|

|-
|Williams
|Service Bulletin Book, Fall 1994
|[[file:Williams-service-bulletin-book-1994-fall-cover.jpg|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1994-fall.pdf PDF]
|Popeye, Indiana Jones, Star Trek, Addams Family, Demolition Man, Flintstones
|

|-
|Williams
|Service Bulletin Book, 1995
|[[file:Williams-service-bulletin-book-1995-cover.png|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1995.pdf PDF]
|World Cup Soccer, Corvette
|

|-
|Williams
|Service Bulletin Book, 1996
|[[file:Williams-service-bulletin-book-1996-cover.png|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1996.pdf PDF]
|Congo, No Fear, Indianapolis 500, Jackbot, Johnny Mnemonic, Road Show, The Shadow, Theatre of Magic
|

|-
|Williams
|Service Bulletin Book, 1997
|[[file:Williams-service-bulletin-book-1997-cover.png|thumb|left|140px]]
||[http://howtopinball.com/files/pinball/paperwork/williams/service-bulletins/williams-service-bulletin-book-1997.pdf PDF]
|Johnny Mnemonic, Junkyard, Safecracker, Scared Stiff, Tales of the Arabian Nights
|

|}

Individual Game-Specific Service Bulletins:
* Service Bulletin #98 (5/97): Scared Stiff; Left Ramp Repair Kit. [https://www.ipdb.org/machine.cgi?id=3915 IPDB]
* Service Bulletin #99 (5/97): NBA Fastbreak; Ball trap fix. [https://www.ipdb.org/machine.cgi?id=4023 IPDB]
* Service Bulletin #101 (12/97): Cirqus Voltaire; Disappearing jet bumper assembly not releasing. [https://www.ipdb.org/machine.cgi?id=4059 IPDB]
* Service Bulletin #102 (12/97): Cirqus Voltaire; Installation instructions for Upgrade Kit #A-22270. [https://www.ipdb.org/machine.cgi?id=4059 IPDB]
* Service Bulletin #104 (4/98): Cirqus Voltaire; Adjustment Sheet Update. [https://www.ipdb.org/machine.cgi?id=4059 IPDB]
* Service Bulletin #107 (12/99): Champion Pub; Arms breaking prematurely. [https://www.ipdb.org/machine.cgi?gid=4358 IPDB]

===Documentation Errors===
* Schematic errors in Addams Family & Addams Family Gold Manuals for the [[#TAF & TAFG Extra Flipper Power Supply (A-15416)|Extra Flipper Power Supply Board (A-15416)]].
* WPC SChematic Manual 16-9473 to 16-9473-2: Switch row 7 & 8 are reversed from what is printed. Row 7 should be pin 5 of U19, and row 8 should be pin 7 of U19.

==Technical Info==
At the heart of the WPC MPU is the Motorola 68B09EP microprocessor, running at 2Mhz. Note that the "E" suffix indicates externally clocked and is necessary to work in a WPC MPU. The "P" suffix merely indicates a "plastic" chip case. 6809 processors lacking the "E" suffix will '''not''' work in a WPC MPU.

The 68B09EP is a 2Mhz, 8-bit/16-bit CPU, with a 64KB address space. Bank switching is required to address more than 64KB. Bank switching is accomplished by the ASIC in WPC systems. The game ROM size varies from 128KB to 8MB, depending on the game. 8KB of battery backed RAM is available to the processor.

For more information, see [https://web.archive.org/web/20110122183733/http://www.oddchange.com/freewpc/manual/The-WPC-Hardware.html The FreeWPC Manual (Archive.org link)]
===WPC Parts List Lookup===
A really nice utility has been put together by Øyvind Møll, enabling lookup of WPC parts. The utility can be used to see which games used particular parts. The utility can be found [http://www.moll.no/pinball/parts/ here].

===WPC System Generations===
====WPC CPU====
[[File:WPC-089_MPU.jpg|200px|thumb|right|WPC-089 CPU, this one from Twilight Zone, with battery holder removed.]]
The WPC CPU was the cornerstone of the new WPC pinball system, introduced by Williams in 1990.

The board has the following features:
* Motorola 68B09E processor
* Switch matrix inputs
* 8k of CMOS battery-backed memory
* A single EPROM, sized from 128K (1 megabit, 27C128) to 1M (8 megabits, 27C080 / 27C801)
* Watchdog circuit and master reset
* Three digital I/O ports - general-purpose; display; auxiliary (labeled "display")
* WPC ASIC - an 84-pin PLCC that has decoding, watchdog, and real-time clock circuitry.

'''What Goes Wrong'''

'''Loose Chips''' - resets and strange behavior

The natural heating and cooling cycle, and vibration, in a pinball machines causes the socketed chips to slowly walk out of their sockets. This loosening can cause mysterious behavior and resets. Firmly pressing each socketed device - including the ASIC - and listening for a small click can solve many odd problems.

'''Battery Corrosion''' - rows of switches failing

When batteries reach old age, they always leak electrolyte. In WPC boards, this electrolyte drips onto the switch matrix circuits. There, it causes extensive corrosion. The corrosion will eat up traces under the green solder mask, creating a lumpy appearance. This corrosion is extremely destructive. It must be caught early, and gently washed with vinegar. Damaged components must be replaced, and damaged traces cleaned with a fiberglass brush and carefully tinned with a soldering iron. Battery corrosion can render a board unrepairable, or undesirable.

''' The Switch Matrix ''' - assorted switch problems

The WPC system, like many pinball machines, uses a switch matrix to read the switches. The matrix is 8 rows by 8 columns, and can read 64 switches with just 16 wires. Under the playfield, the wires snake between the lights, creating strings of rows and strings of columns. The lights are isolated with diodes.

The root cause of switch matrix problems on the WPC CPU is often a voltage short to the switch matrix. This can happen with residual charge from the solenoid or flasher supply, so the machine does not have to be on for damage to occur. One easy way to do this is to touch a coil lug while adjusting slingshot switches. The row detectors - the LM339s - are quite safe from everything but the 70V solenoid voltage, and will often survive that. The column drivers, however, are directly exposed to the wiring. So many shorts - from the GI; lamp matrix; flashers; or solenoid wiring can destroy the driver. A solenoid wiring short will often destroy the 74LS374 at location U14 ahead of the driver as well.

The symptom of a bad driver is a column short that does not go away when the playfield is disconnected. A bad driver may also be confused by neighboring columns, so switches may register twice.
 

[[File:TheCapacitorToNowhere.jpg|200px|thumb|left|This "missing" bypass capactor isn't missing at all.]] 
The WPC CPU is stuffed with a "bypass capactor" to the right of the ULN2803. Bypass capacitors filter high frequency noise from the 5VDC power at each integrated circuit (generally). This one...in some revisions of the PCB, isn't connected to anything on one side. It can safely be removed, or more likely, simply not be replaced when abating alkaline corrosion.
 

===== WPC-089 Signal Map (pinouts) =====
[[File:WPC89 CPU compnt-side ZAZ FEB2017-10.jpg|200px|thumb|left|Component Side.]][[File:WPC89 CPU solder-side ZAZ FEB2017.PNG|200px|thumb|right|Solder Side.]] 
The two diagrams (left and right) show the signal pinout for the entire WPC-089 MPU, both front and back side view. ''Images provided by Sascha Voskuil.''
 

===== WPC-089 Bare PCB Images =====
The following images are provided for reference.

<center>
<gallery widths=250px heights=200px perrow=4 caption="WPC-089 OEM MPU PCB Traces">
File:WPC-089-U1.JPG|<center>U1</center>
File:WPC-089-U2.JPG|<center>U2</center>
File:WPC-089-U3.JPG|<center>U3</center>
File:WPC-089-U4.JPG|<center>U4</center>
File:WPC-089-U5.JPG|<center>U5</center>
File:WPC-089-U6.JPG|<center>U6</center>
File:WPC-089-U7.JPG|<center>U7</center>
File:WPC-089-U8.JPG|<center>U8</center>
File:WPC-089-U9.jpg|<center>U9</center>
File:WPC-089-U11.JPG|<center>U11</center>
File:WPC-089-U12.JPG|<center>U12</center>
File:WPC-089-U13.JPG|<center>U13</center>
File:WPC-089-U14.JPG|<center>U14</center>
File:WPC-089-U15.JPG|<center>U15</center>
File:WPC-089-U16.JPG|<center>U16</center>
File:WPC-089-U17.JPG|<center>U17</center>
File:WPC-089-U18.JPG|<center>U18</center>
File:WPC-089-U19.JPG|<center>U19</center>
File:WPC-089-U20.JPG|<center>U20</center>
File:WPC-089-U21.JPG|<center>U21</center>
</gallery>
</center>

====WPC-S CPU====
[[File:WPC-SCPU.jpg|200px|thumb|left|WPC-S CPU]]
[[File:WPC-SMPU.jpg|260px|thumb|right|WPC-S CPU with daughter card intalled. Battery holder replaced with coin cell battery.]]
The WPC-S CPU is the second generation of WPC CPU board. The designer switched to a remote battery holder, located on a daughter board that clips to posts on the lower half of the board. This approach mostly eliminated the PCB damage caused by battery leakage. The next version of the board, the WPC-95 CPU board, switched to a plastic battery holder that doesn't provide quite as much alkaline corrosion protection to the board.
The board also has different switch matrix connectors than WPC and WPC-95.

The digital I/O connectors remain unchanged from the WPC CPU.

The most significant difference was the introduction of the security PIC. This devices contains a serial number and a handshake mechanism. The serial number is displayed at startup, and allowed the manufacturer to identify the dealer who sold a machine into a particular region. This approach was necessary when substantial price differences were common across Europe, to prevent grey imports.

To prevent simple removal of the PIC, the device also controlled the switch matrix, and would not operate without a correct machine code from the WPC CPU. Therefore, there is one PIC for each machine. An incorrect or defective chip will result in a "G13 error" or "U22 error" at startup.

When buying a used WPC-S MPU, the battery holder is often missing. If connecting a battery pack, a Molex housing and 2 crimp contacts is needed. The part number for the 5 pin housing is 50-57-9405 (Digikey WM2903-ND). The crimp contacts are part number 16-02-1125 (WM2554-ND).
 

====WPC-95 CPU====
[[File:WPC95CPU.jpg|200px|thumb|left|WPC-95 CPU Board]] 
The WPC-95 CPU is the third generation of the WPC CPU design. It includes the security PIC added in the WPC-S system, and returns to an on-board battery holder. The new battery holder has a large plastic shell, designed to shield the PCB from any battery leakage. The pinout of the switch matrix connectors changed again from WPC-S.
 

===== WPC-95 CPU Factory Modification =====
[[File:WPC95FactoryMod.png|200px|thumb|left|WPC-95 CPU Board factory mod. Drawing by Sascha Voskuil.]] 
CPUs manufactured for Jack*Bot and Congo sample games before 12-15-95 have a factory modification that includes one cut, an additional diode, and an additional resistor. Williams [http://www.planetarypinball.com/mm5/Williams/tech/sb86.html Service Bulletin 86] details the reason for the mod, premature loss of backup battery voltage.
 

===WPC Power/Driver Board Generations===
====WPC-89 Power/Driver Board====
The WPC power-driver board converts AC power from the transformer; drives the solenoids; drives the lamp matrix; drives the GI lamps; and detects flipper switch operation in non-FlipTronics machines.

There are three known variants of the WPC-89 driver board: A-12697-1, A-12697-3, and A-12697-4.

The power-driver board has the following functions:
[[File:WPC089 power summary.png|240px|thumb|left|Summary schematic of WPC '89 Power Driver board showing test LED's and test points. A PDF of this image can be viewed [[Media:WPC089 power summary.pdf|here]]]]
[[File:WPC_Power_-Driver_Board.jpg|200px|thumb|right|WPC Power-Driver board with Flipper Relay, or the -1 version.]]
[[File:WPCPowerDriverBoardWithoutFlipperRelay.jpg|200px|thumb|right|WPC Power-Driver board without Flipper Relay, or the -3 version.]] 

*AC rectification and smoothing for 70VDC solenoid voltage
*AC rectification and smoothing for 20VDC flasher voltage
*AC rectification and smoothing for 18VDC lamp matrix voltage
*AC rectification and smoothing for unregulated 12V supply
*AC rectification and smoothing for 5VDC flasher voltage
*Regulated 12V supply
*Regulated 5V supply
*6.3VAC supply for GI circuits
*Power control for high power solenoids (drives 1 - 8, Q64 through Q82), with clamping diode connected to 50VDC
*Power control for low power solenoids (drives 9 - 16, Q44 through Q58, with clamping diode connected to 50VDC
*Power control for flashers (drives 17 - 20, Q36 through Q42), without a clamping diode at all
*Power control for "special" solenoids (drives 21 - 28, Q20 through Q34), with clamping diode that must be connected to the power source driving the device. In practice, this is always the 50VDC power source.
*Power control for lamp matrix
*Power control for pre-FlipTronics flippers (not on all boards)
*Sense optos for pre-FlipTronics flippers (not on all boards)
*Power control for 5 6.3VAC GI channels using four-sector triacs
*Zero crossing sense for AC line in
*Logic interface to WPC CPU
 

[[File:Dash-1Conversion.jpg|300px|thumb|right|A -3 WPC Power/Driver board retrofitted with the minimum parts required to add -1 functionality. Note: R210 and R211 still need to be populated on this board.]] 
The newer generation -3 and -4 boards can be converted to -1 board configuration by populating the following components:
*D39 - 1N4004
*U7/U8 - 4N25 (or 4N35)
*R210/R211 - 3.3K/5W Resistor
*RLY1 - 6VDC 4PDT Relay
*J110 - 9-pin .156 header
*Q99 - 2N5401 transistor
*R208 - 270 ohm 1/4W resistor
*R209 - 4.7K ohm 1/4W resistor

In the image at right, some components remain unpopulated. Those components are part of the line level voltage circuitry that drives LED2 and LED3. The line level voltage circuitry does not work very well and can not be relied upon. Hence, there is no reason to populate those components.

=====WPC Power/Driver Board Layout Errors=====
======C9 Connection Error======
[[File:WPCPowerDriverBoardC9Correction.jpg|200px|thumb|left|WPC Power/Driver board with C9 connection corrected.]]
[[File:WPCPowerDriverBoardC9CorrectionSchematic.jpg|200px|thumb|right|Image of WPC Power/Driver board schematic, showing LM323K 5VDC regulator and C9.]] 
At the time that this PCB was laid out and manufactured, a small tantalum capacitor, located at C9, was connected to the wrong side of the LM323K 5VDC regulator. While it should have been connected to Vin, it was in fact connected to Vout. The picture at left shows a method to correct the board so that it matches the schematics, also shown at left. In this picture, an additional "tab" was added to the top bolt of the regulator and soldered to ground, creating a redundant path to ground for the regulator.

Note that while the schematics show this capacitor as .33µF, it is listed as 2.2µF in each game's parts listing, matching the capacitor that is actually installed.

This change isn't generally considered necessary and not thought to be a significant contributor to game resets. The original purpose of the cap was to filter high frequency noise. According to the LM323K datasheet, a 1 to 2µF tantalum capacitor should be added to the input of the LM323K if the regulator is more than 4" away from the main filter capacitor. The regulator is just inside of 4" from the 15,000µF filter capacitor at C5. As it sits on Vout, it causes no harm, but does no good either.
 

======J122/J124, pin 1 Connected to Board Ground======
[[File:WPCPowerDriverBoardLayoutError.jpg|200px|thumb|left|Two power/driver boards showing the factory corrected trace routing (bottom) and a later version of the board with the correction incorporated into the PCB mask (top).]] 
Some revisions of the WPC power/driver board, were manufactured with J122 and J124, pin 1, connected to board ground. This would cause whatever is connected to those connector positions, to be turned on constantly. For the game Twilight Zone, this would result in the left mini-playfield magnet being powered constantly. The picture at left shows a factory modification to the power/driver board to rectify the problem.
 

====WPC-95 Power/Driver Board====

The WPC-95 Power/Driver board performs all of the same functions as it's WPC predecessor, and also integrates flipper power circuits into the design, eliminating the need for the FlipTronics board present in WPC FlipTronics I & II games as well as WPC-S games. The bridge rectifiers are replaced by ganged 6A2 diodes and the filter capacitors were spec'd down from 15,000µF to 10,000µF. While the WPC P/D board supported brightness control of 5 general illumination circuits, the WPC-95 P/D board can control brightness of only 3 general illumination circuits. The two remaining GI circuits are used for backbox illumination.
[[File:WPC095 power summary.png|240px|thumb|left|Summary schematic of WPC '95 Power Driver board showing test LED's and test points. A PDF of this image can be viewed [[Media:WPC095 power summary.pdf|here]]]]
[[File:WPC-95PowerDriverBoard.jpg|200px|thumb|right|WPC-95 Power/Driver board. This is the later model, with zero ohm jumpers installed in the GI circuit, lower left.]]
 

===WPC Alphanumeric Display Driver Board===
The Alphanumeric display driver board was used in Funhouse, Harley Davidson, and The Machine: Bride of Pin*bot. The board still contains the high voltage handling ICs, UDN6118 and UDN7180. It also has its own high voltage generation circuit that is a carryover from earlier Williams high voltage display circuits.
[[Image:WPCAlphaNumericDisplayDriverFront.jpg ‎|250px|thumb|left|WPC Alphanumeric Display]]
[[Image:WPCAlphaNumericDisplayDriverRear.jpg ‎|250px|thumb|left|WMS A-12739-1 WPC Alphanumeric Display Driver PCB]]
 

===WPC Dot Matrix Controller board===

[[Image:WPC DMD Controller.jpg|200px|thumb|left|WPC DMD Controller board]]
The WPC DMD display and DMD controllers are common features in Williams 1990's era pinball machines. The display is a high-voltage plasma system that has scanning electronics built in. The WPC dot matrix controller board, or WPC-95 AV (Audio/Video) board in later machines, provides the power for operation, and maintains the display dot images in its memory. The CPU loads these pages ahead of time, then instructs the display controller to "flip" the images onto the screen.

Note that sometimes U12 is stuffed on this board and sometimes it is not. There is no functional difference whether U12 is stuffed or not.

Clive at the Coin-Op Cauldron has written an excellent article detailing some of the nitty gritty of the DMD controller. The article can be found [http://coinopcauldron.com/dotarticle.html here]. 

===WPC Sound Boards===
====WPC pre-DCS Sound Board====
[[Image:WPC Sound Board.jpg|200px|thumb|left|WPC pre-DCS Sound Board, sound ROMs removed]]
The pre-DCS sound board uses a single LM1875 amp and can accommodate up to 3 sound ROMs. With a single "sound lane" and amp, stereo sound is not possible. The three speakers are connected in series, each of them attempting to accentuate different bands of the audio spectrum. A broken wire to any of the three speakers will result in no sound at all.
 

====WPC DCS Sound Board====
[[File:WPC DCS Sound Board.jpg|200px|thumb|left|The WPC DCS Sound Board]]With Indiana Jones: The Pinball Adventure, Williams introduced the DCS sound system. Its DSP architecture was a significant improvement on earlier systems, and it allowed Williams to use recorded music from EPROM rather than synthesizer music. The board also introduced dual amplifiers and an electronic crossover. DCS allowed Williams to use compressed sound samples, significantly improving the sound quality of the games.

The board dropped the microprocessor controlled synthesizer chip and sound bite system of earlier WPC machines, and replaced them with the still in production Analog Devices ADSP-2105 DSP. For its time, this was an extremely fast device (40MHz), and is capable of providing all of the sound processing needed in a WPC pinball machine. The ADSP-2115 can also be used as a replacement for the 2105. It adds a second serial port which is not used in WMS pinballs. Williams also upgraded the chip amp. The new chip amp operates at a lower voltage, and forced a corresponding change in the transformer voltage (12VAC + 12VAC). Therefore, DCS machines have different transformer winding to previous WPC machines. The system has an electronic crossover, separating high frequencies to the backbox and low frequencies to the cabinet.

The card connects to the WPC CPU through the I/O port. It shares the port with the Fliptronics board and the display board.
 

'''What's on the Board?'''

The DCS sound board has the following subsystems:

* Rectifier and fused power supply for +/-16VDC amplifier power [check - WPC was 35V?]
* Dual-channel power amplifier with electronic crossover
* DSP-based sound synthesizer
* One EPROM for DSP code storage
* Other EPROMS for sound storage
* High-speed program memory for the DSP
* Mailbox interface for WPC-CPU

On power-up, the board runs a diagnostic and sounds a bong. It does this without any help from the WPC CPU. If there is no bong, the board has a problem.

'''What Goes Wrong'''

The smoothing capacitors C20 and C21 are often at the end of their useful lives. The chip amp, like the Honey Badger, really doesn't care, and will accomodate capacitor variance. However, replacing them will make even the pre-DCS sound much richer.

The coupling capacitors at C32 and C41 can fail.
 

====WPC-95 AV Board====
[[File:Wpc95AV.jpg|200px|thumb|right|WPC-95 AV Board]]
The WPC-95 AV board integrated the sound and video system into a single board, siginifcantly reducing power and space.

The board has the following major subsystems

'''ASIC'''
The ASIC is a 208-pin flatpack device. It incorporates the following functions:
*Interface registers to CPU
*Memory control and display output logic for the diaplay subsystem
*Memory interface for the AD2105 DSP

The ASIC has a tendency to fail in such a way that the sound disappears. New ASICs are available, but replacing them requires skill with surface mount devices.

'''Audio DSP'''
The audio susbsystem uses the same part as the DCS sound board the Analog Devices DSP part ADSP-2105 and an AD1851 DAC. For its time, this was an extremely fast device (40MHz), and is capable of providing all of the sound processing needed in a WPC pinball machine. The AD1851N in DIP package was discontinued 2010 but the DSP is still available at Digikey and many other stores (ADSP-2105BPZ-80 ).

Location: lower center of board

'''Serial Port'''
The serial port is rarely populated. Its uses include: machine debugging; machine linking ([[NBA Fastbreak]]); ticket printers

Location: lower left of board

'''Audio Amplifier'''
The audio amplifier is a dual-channel TDA 2030A operating at X volts. The system has an electronic crossover, separating high frequencies to the backboox and low frequencies to the cabinet.

Location: lower right of board

'''DMD Power'''
The DMD nominally requires 62, -100 and -112VDC to operate. The board uses a temperature-compensated design to supply these voltages.The -112VDC line is built as a 12V offset from the -100VDC line.

Location: upper right of board.
 

===WPC FlipTronics I & II Boards===
Beginning with The Addams Family, Williams implemented the FlipTronics flipper power and switch sensing system. The Addams Family and The Addams Family Gold were the only two games which used the FlipTronics I board. Subsequent games until the WPC-95 board set debuted used the FlipTronics II board. FlipTronics II boards are backward compatible with the FlipTronics I board. The three FlipTronics II board revisions (A-15472, A-15072-1, and A-15472-1) are interchangeable. The WPC-95 board set integrated the flipper electronics into the driver board.

[[File:WPC_Fliptronics_I_Board.JPG|200px|thumb|left|WPC Fliptronics I Board]]
[[File:WPC Fliptronics II.jpg|200px|thumb|right|WPC Fliptronics II Board]] 
Prior to the FlipTronics system, flipper circuit design had essentially been the same simple circuit. This circuit consisted of power to two flipper coil windings (the "power stroke" and "hold" windings). When the flipper cabinet switch was closed, the power winding and hold winding were both energized. As the flipper plunger was pulled in, the flipper EOS switch opened, interrupting power to the "power stroke" winding, leaving only the "hold winding" energized to hold the flipper in the up position. Flipper coil systems were designed this way so a flipper could be energized indefinitely (in theory). A failed EOS switch could result in weak flipper performance (poor EOS switch conduction) or result in burned flipper coils (EOS switch that never opens). 

The FlipTronics system ended reliance on properly operating EOS switches. While FlipTronics systems still have EOS switches, they generally are not used to control power to the coil windings. The EOS switch provides feedback to the MPU that the flipper has completed a stroke. A failed EOS switch will not cause damage to either the coil or to the switch circuitry. If the MPU doesn't receive feedback that the flipper has completed a full stroke within a specific time (milliseconds), the "power stroke" winding power will still be interrupted.

There is a special case where a properly operating EOS switch comes into play. The EOS switch on FlipTronics games helps to keep the flipper bat in the up position when a fast moving pinball strikes the flipper. When the ball strikes the flipper, moving it toward the "at rest" position, a properly operating EOS switch will open. The FlipTronics board will then provide a path to ground for the "power stroke" winding until the flipper completes the upward stroke, closing the EOS switch again. Games with broken or malfunctioning EOS switch(es) may allow the flipper bat to drop all the way to the "at rest" position when struck by a rapidly moving ball, with possible loss of ball, and a great deal of "what the @#$% just happened".
 

'''FlipTronics game flipper operation: '''
#Flipper power is always present at the flipper coil lugs. For the flipper to actuate, that coil power needs to find a path to ground.
#The FlipTronics board switch sensing circuitry recognizes closure of a flipper cabinet switch.
#The FlipTronics board communicates closure of the flipper cabinet switch to the MPU.
#The MPU commands the FlipTronics board to provide ground for the "power stroke" winding of the flipper coil (via a circuit passing through a 2N5401, TIP-102, and TIP-36C). This process is similar to how high powered coils are controlled by the power driver board.
#A few milli-seconds later (thousandths of a second), the MPU commands the FlipTronics board to interrupt the ground path for the power stroke winding and to provide ground for the hold winding portion of the coil (via a circuit passing through a 2N5401 and a TIP-102).
#The FlipTronics board switch sensing circuitry recognizes close of the flipper EOS switch, and communicates that switch closure to the MPU. Again, this switch closure isn't used to control power to the flipper coil windings. It's merely information.
#When the player releases the cabinet flipper switch, the FlipTronics board again senses that open switch, communicates the change in state to the MPU which then commands the FlipTronics board to interrupt ground to the hold winding also, and the flipper returns to it's at rest position.

WPC-95 games use the exact same methods. However, the WPC-95 board set integrates the capabilities of the FlipTronics board into the power driver board.

The FlipTronics II board also rectifies AC voltage sourced from the game transformer, and relayed to it from the Power/Driver board to create the 70VDC flipper power (the FlipTronics I board relies an an "extra flipper power supply" to rectify the flipper voltage). A FlipTronics board can sense 8 switches, and control up to four flipper power and hold windings. In some games, spare flipper cabinet switches, EOS switches, and coil drive circuits are used for other game features.

Note that sometimes C2 is installed on this board and sometimes it is not. The board pictured does not have C2 installed. Since C2 is a 100µF/100V capacitor, it can't be doing too much AC smoothing of the full wave rectified flipper power. Some RGP discussions indicate that C2 may have been designed in originally to reduce EMI (electro-magnetic interference) from the board. Installing C2 will have a negligible affect on flipper power. Some report that installing C2 fixes a "jittery gate" symptom on BSD's "mist" assembly.

More information about bench testing FlipTronics board is available [[Leon_Borre_WPC_Fliptronics_board_repair | here]].
 

===Miscellaneous WPC Boards===

====WPC 7 Opto Board (A-14977, A-15576, A-15595)====
[[File:7OptoBoard.jpg|300px|thumb|left|Example WPC 7 Opto Board, as found in AFM and many other WPC games.]]
This board is a typical example of a WPC opto board.

The connector on the lower left (as pictured) provides the power for seven IR emitters. The emitters are powered from the 12V supply through a 260 ohm resistor (the large blue resistors adjacent to the connector). Williams runs the opto emitters at about 40mA, which results in the resistors becoming hot. The opto boards are often darkened by the heat, as this one is.

The connector on the upper left carries the signals for the photo-transistors. The photo-transistor collector connects to 12V, and its emitter connects to ground through two 2KOhm resistors connected in series. When the transistor is illuminated by the emitter, it passes more current through the resistors, raising the input voltage on the LM339. The other pin on the LM339 is set to about 2.8V buy a 100K/22K voltage divider. Therefore, when the voltage at the junction of the two 2K resistors and the LM339 input is above 2.8V, the switch will read as closed. This happens at 1.4mA.

The two left side connectors can be used for optical trough switches. The connector on the right hand side provides the the row/column switch matrix interface to the MPU. 

'''What Goes Wrong?'''

The resistor discoloration is cosmetic, and rarely causes problems. The biggest problem for these boards is switch matrix shorts. If any of the power lines hits the switch matrix, it can easily destroy the LM339 and possibly its output diode. This issue will manifest as a ground short on one or more rows. It can be tested by removing the switch matrix connector. If the problem goes away, the associated LM339 and possibly its diode need to be replaced.

If the short was from the 70V supply, multiple LM339s may be damaged.

Replacing LM339s on these boards needs to be done carefully, as it is easy to lift traces and pull the through-hole plating. Always socket replaced ICs.

====WPC 10 Opto Board (A-15430, A-18159, A-20246) ====
[[File:WMS 10 Opto.jpg|300px|thumb|left|Example WPC 10 Opto Board.]]
The 10 opto board was used in Bram Stoker's Dracula, Dr. Who, Indiana Jones, Pinball Circus, Popeye, Cactus Canyon, Corvette, Monster Bash, Medieval Madness, Revenge From Mars, SafeCracker, SWE1, Shadow, Congo, Indianapolis 500, and World Cup Soccer.

The connector on the upper left carries the power for seven of the IR emitters. The emitters are powered from the +12V supply through a 260 ohm resistor (the large blue resistors adjacent to the connector). Williams runs the opto emitters at about 40mA, which results in the resistors becoming hot. The opto boards are often darkened by the heat, as can be viewed in the adjacent picture.

The connector on the lower left carries the signals for the photo-transistors. The photo-transistor collector connects to +12V, and its emitter connects to ground through two 2KOhm resistors connected in series. When the transistor is illuminated by the emitter, it passes more current through the resistors, raising the input voltage on the LM339. The other pin on the LM339 is set to about 2.8V by a 100K/22K voltage divider. Therefore, when the voltage at the junction of the two 2K resistors and the LM339 input is above 2.8V, the switch will read as closed. This happens at 1.4mA.

These two connectors can be used for optical switch troughs. The three connectors on the right hand side each carry signals for one transmitter/receiver pair. These connections are often used for ramp entrances, and sometimes the pair is mounted on a single bracket.

The connector on the bottom provides the the row/column switch matrix interface to the MPU. 

=====WPC 10 Opto Board Problems=====
'''What Goes Wrong?'''
[[File:10OptoBoardCorrosion.jpg|300px|thumb|right|The leaky capacitor removed and shown in this picture, spewed enough electrolyte to completely eat through the power trace, causing the board fail.]]‎
The resistor discoloration is cosmetic, and rarely causes problems. The biggest problem for these boards is switch matrix shorts. If any of the power lines hits the switch matrix, it can easily destroy the LM339 and possibly its output diode. This issue will manifest as a ground short on one or more rows. It can be tested by removing the switch matrix connector. If the problem goes away, the associated LM339 and possibly its diode need to be replaced.

If the short was from the 70V supply, multiple LM339s may be damaged.

Other symptoms of failed LM339's can include:
* Intermittent ground shorts on one or more switch matrix rows. Sometimes this can be mistaken for a connector issue since the ground short warning message and row(s) of closed switches in the edge switch test may appear and disappear at random.
* Sometimes the switch edge test can show one or multiple opto switches flickering open and closed. This can sometimes be mistaken for a connector or individual opto issue, as it can come and go at random.
* In switch edge test, one opto switch can activate an entire row of opto switches, but might not actually show the ground short warning.

Replacing LM339s on these boards needs to be done carefully, as it is easy to lift traces and pull the through-hole plating. Always socket replaced ICs.

Another common issue is the 100uf/35V electrolytic capacitor at C1 will leak corrosive liquid that eats through the traces under it. This interrupts the power supply.

====WPC Custom 10-Opto Board (Twilight Zone)(A-16807)====
[[File:TZ10OptoBoard.jpg|300px|thumb|left|Twilight Zone specific 10 Opto Board.]] 
This 10-Opto board appeared only in Twilight Zone. As can be seen, it differs in pinout (at the very least) from the more ubiquitous 10-Opto board above.

'''What Goes Wrong?'''

See "[http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#WPC_10_Opto_Board_.28A-15430.2C_A-18159.2C_A-20246.29 WPC 10 Opto Board (A-15430, A-18159, A-20246)]", above.
 

====WPC 16 Opto Board (A-16998, A-17223)====
[[File:16OptoBoard.jpg|300px|thumb|left|WPC 16 opto boards, both versions]]This board is used in at least Star Trek: The Next Generation, Junkyard, and Champions Pub. Note the two different "versions". The bracket on one side is believed to be part number 5768-13739-00 while the bracket on the other side is believed to be part number 5768-13739-01. The boards are identical in layout and components. The only difference is bracket mounting, some silk screening, and one version has holes in the PCB which are not used.
 

====8 High Power PCB Assembly (A-16116)====
[[Image:A16116-8-HighPowerPCBAssembly.jpg|300px|thumb|left|A 8 High Power PCB Driver Board as used in ''Twilight Zone'']] 
The 8 High Power PCB was used only on Twilight Zone. It has the capacity to drive 8 high power coils if fully populated. Instead, it drives 5 high power coils as populated for Twilight Zone. This simple board is merely an extension of the power/driver board solenoid drive circuitry designed to accommodate the extra coils incorporated into the Twilight Zone design. It replicates the power/driver board circuitry of the TIP-36c transistors.
 

====Auxiliary 8-Driver Board (A-16100)====
[[Image:8 driver board.JPG|300px|thumb|left|An example 8-Driver board]]
[[Image:A-16100-8DriverBoard.jpg|300px|thumb|right|A-16100 Schematics]] 
The auxiliary 8-driver board sits in the top right of the backbox in a handful of WPC machines. The board is designed to run flashers, low-power solenoids, and perhaps motors.

The connector labeling is tricky as the 8-Driver board is controlled by a ribbon cable that is connected to the "Display" connector on the WPC CPU board (J204). The "Display" label is a historical artifact and refers to the alphanumeric display used in Funhouse. 

The board has 8 outputs, driven by TIP-102 transistors with a 2N4403 pre-driver, similar to the WPC power/driver board (which uses a 2N5401 as a pre-driver). The board is used in the following games:
*Demolition Man
*Indiana Jones
*Road Show
*Star Trek: The Next Generation
*Twilight Zone

The board circuitry can be jumpered to add one or two more columns to the switch matrix. This makes the board more flexible but also may require different jumpers to use the board in different games (i.e. the boards are not completely interchangeable between games "as is").

Jumpers to be installed for Demolition Man and Roadshow should be...
*PW1, PW3, PW5

Jumpers to be installed for Twilight Zone, Star Trek: The Next Generation, and Indiana Jones should be...
*SW2, SW4, SW6

Indiana Jones, Star Trek: The Next Generation and Twilight Zone use Q12 via the J5-1 connection to add this column. Although Twilight Zone adds the column, the column isn't displayed during switch test (T.1). The column is used to read the 8 optos in the clock mechanism.

=====Auxiliary 8-Driver Board Problems=====
What Goes Wrong? 
This is a pretty simple board. Generally, the problem is going to be a blown transistor, or rarely, a failed 74ALS576 latch.

A problem which may occur are locked-on coils or flashers. This can be caused by the ribbon cable not being firmly seated. This can happen during the game or in attract mode and is caused by floating data line signals to the 8 Driver Board. A remedy has been found to solve this problem. This involves soldering a 10K resistor from the CLK to 5V and a resistor array 8x10K to pull down all data lines to GND. More information about this modification can be found under the [[Star_Trek:_The_Next_Generation#Diode_.22Tie_Back.22_missing_causes_8-Driver_Board_transistor_to_fail|"Diode Tie Back Missing Causes 8-Driver Board Transistor to Fail" section on the Star Trek: The Next Generation page]]

[[Image:STTNGDiodeTieBackAtCoilPower.jpg|300px|thumb|left|Diode tie-back at the single drop target assembly. Note the small purple/green wire soldered to the target reset coil's power side (two larger gauge purple/green wires).]] 
Another thing to watch for is a "diode tieback" connection to the board for games like Star Trek: The Next Generation. Without this "diode tieback", transistors on the 8-Driver board WILL be damaged. The diode tie-back wire is purple/green and connects from the coil power side of one of the drop target assembly coil lugs to J4 pin 1 on the 8-Driver board. If the solder connection at the coil lug is solid, suspect the wire connection at the IDC connector. Repinning this connection with good a quality crimp-on TriFurcon pin is advised.
 

====Sound Overlay Board (A-13502)====
This board acted as a power supply for a small subset of Funhouse and Dr. Dude games during the transition from System 11 to WPC in cases where the WPC boardset still included the [[Williams_System_9_-_11#Sound_Boards|System 11 D-11581 sound board]].
[[File:Placeholder.jpg|300px|thumb|left|Sound Overlay Board (A-13502)]] 

====Attack from Mars "Strobe" Board (A-20669)====
[[Image:AFMStrobeBoard.jpg|300px|thumb|left|A-20669 Attack From Mars Strobe Board]] 
The strobe board at left is unique to Attack from Mars. Williams used underrated 100µF/100V non-polarized caps on the board that often fail with the telltale "bulge" at one end. The "transformer" on the board (blue rectangular box, lower/right in the picture) has very fine legs which can break due to vibration at the back of the playfield.

Excellent repair information for this board can be found [http://www.iobium.com/fixing_the_afm_strobe_board.htm here] and a possible replacement for the overloaded non-polarized capacitors [http://kcpins.com/archives/63 here].
 

====Trough Opto Boards====
When WIlliams moved to the gravity trough, they also switched to optical switches to detect the ball. The trough is covered by a Williams patent.

There are two generations.

[[File:WMS A-17982 WPC Trough Transmitter.JPG|thumb|300px|left|WMS A-17982 Trough Transmitter Board - First Generation]] 
[[File:WMS A-17981 WPC Trough Receiver.JPG|thumb|300px|left|WMS A-17981 Trough Receiver Board - First Generation]] 
The first generation (Judge Dredd - Indiana Jones ???) used a receiver board with all of the switch logic on the board. The vibration in the trough makes extra components subject to failure. The second generation (xxx -) uses a regular opto board, and the trough receiver just has phototransistors.

As with all Williams opto circuits, the transmitters are driven to the very limit, and the series resistors overheat. This overheating destroys the solder joints.

Also, the continued vibration makes the resistor legs crack, and weakens the pins in the IDC connectors.

Later versions used rubber grommets to isolate the boards from the trough. 

=====Trough Problems=====
'''What Goes Wrong?'''

======Broken Parts Leads======

[[File:WMS WPC Trough Transmitter Reworked.JPG|thumb|left|300px|Typical Trough Opto Transmitter Boards after resistors have been replaced or soldered multiple times]]

The resistors on the emitter board are subject to cracked legs. Wiggle them to see if they are good. replace the resistor if there are any signs of trouble. On earlier receiver boards, inspect all components.
 

======Trough Divots======
[[File:WMS_WPC_Gravity_Trough_Dimpled.JPG|thumb|300px|left|Typical Trough Divots Caused by Balls]]
Balls make great hammers and, over time, they will beat divots into the trough floor. Then, they will then rest in the divots and cause all kinds of ball count problems. The problem is exacerbated with slightly magnetized balls.

The fix is to file them out, and then sand the metal smooth. A dremel tool with grinding stone works great for this.

Installing a shim that slides over the divots is also a fix for this issue. There use to be both [https://www.pinballlife.com/williamsbally-trough-shimprotector.html metal versions (now PETG)] and [https://www.marcospecialties.com/pinball-parts/03-16809 PETG plastic versions] on the market. Only the PETG plastic versions are available now, as far as we know. The shim eliminates the ability of balls to rest in the divots as well as breaking any magnetic connection, especially with the PETG plastic version.
 

====WH2O Chaser Lamp Board (A-15761)====
[[File:A-15761ChaseLampBoard.jpg|300px|thumb|left|A-15761 Chase Light Board]]
[[File:A-15761Schematic.jpg|300px|thumb|right|A-15761 Chase Light Board Schematic]] 
This board is used for the chaser lamps on Whitewater. It is a simple lamp sequencing board that causes the lamps to "chase".

The board rectifies 16VAC via BR1 and BR2 to create approximately 12VDC to power the chase lamps. The board also receives 12VDC from the power/driver board and regulates it down to 5VDC via an LM7805. This 5VDC is used for the logic level ICs on the board.
 

====CFTBL Chase Light II Board (A-15541)====
[[File:5768-13221-02.jpg|300px|thumb|left|A-15541 Chase Light II Board]]
[[File:A-15541Schematic.jpg|300px|thumb|right|A-15541 Chase Light II Board Schematic]] 
This board is used for the chaser lamps located around the ramps and whirlpool bowl in Creature From the Black Lagoon. 

Eight BT138 triacs, which are pre-driven by 2N4403 transistors, control eight discrete lamp strings. In addition to the lamps chasing, the lamp strings can be dimmed for effect. 

====High Current Driver Board (C-13963)====
[[File:C-13963HighCurrentDriverBoard.jpg|300px|thumb|left|C-13963 High Current Driver board as used in NBAFB and Funhouse.]]
[[File:HighCurrentDriverBoard.jpg|300px|thumb|right|C-13963 High Current Driver board Schematic]]
This board drives the jaw motor for the playfield heckler Rudy in the game Funhouse.

The circuitry is identical to the "Corvette/Road Show Dual H-Drive Motor Control Board" in the next section except that this board controls a single motor only. 

==== Corvette/Road Show Dual H-Drive Motor Control Board (A-19159/A-19242-1)====
[[File:WMSMotorDriveBoard.jpg|300px|thumb|left|Dual H-Drive Motor Control Board (A-19159/A-19242-1)]]
[[File:A-19159DualHDriveMotorControllerSchematic.jpg|300px|thumb|right|Dual H-Drive Motor Control Board Schematic]]
The "Dual H-Driver Motor Control Board" is used on Corvette and on Road Show. For Corvette, it drives the two small motors that animate the two car race track on the right side of the playfield. For Road Show, it controls both Red and Ted's mouth motors.

While the board has two different part number designations, they are, in fact, identical.

Note: Parts enclosed by "Block A" and "Block B" in the schematics are not stuffed.

Operation 
The board is powered by either 12VDC (J118/2, Roadshow) or 20VDC (J107/6, Corvette) from the power/driver board. 
Each "channel" receives a direction and an enable signal. The signal is either grounded or floating. 
Four transistors on the power/driver board provide these signals (three transistors for Corvette as both motors always run in the same direction in game operation, either forward or reverse). 
Grounding the "enable" pin for a channel enables power to the associated motor. 
Grounding the "direction" pin (or leaving it floating) for a channel causes the motor to turn either clockwise or counterclockwise. 
Each channel can be controlled independently. Hence the name, Dual H-Drive.

=====Dual H-Drive Motor Control Board Problems=====
What Goes Wrong? 
Most failures are caused by the two 100uf/35V electrolytic capacitors on the board. They sometimes leak and destroy the power traces beneath them. After that, the TIP102/TIP-107 transistors can fail. These are easily tested using the "diode test". The LM339 is relatively beefy and rarely fails but of course, this is possible.
 

====Bi-Directional Motor Board (A-15680)====
[[Image:A-15680BiDirectionalMotorBoardSchematic.jpg|300px|thumb|left|A-15680 Bi-directional Motor Board]]
[[Image:TraceCloseup-A15680.jpg|300px|thumb|right|Close up view of traces under A-15680 filter capacitor]] 

This board is used in Cirqus Voltaire, Dr Who, Party Zone and White Water.

One problematic aspect of the board's design is that the 100µF electrolytic cap is mounted over the trace that carries 12VDC power to the drive transistors. If the electrolytic cap fails and leaks it's corrosive contents, it will eat through the trace and the board won't work correctly. If this happens in WH2O, Big Foot will not turn his head during game test at boot up. The board pictured at left exhibited this problem and was repaired.

Note that this cap, C2, was sometimes not stuffed at the factory. It's purpose is to filter noise from the 12VDC power, but the power is clean enough that this cap isn't really necessary. Note also that the schematics for the board are in error, designating this 100µF/25V cap as C1 instead of C2 as is silkscreened onto the board.

Another seemingly prevalent issue with this board is failure of the diodes. If either D8 or D9 fail, the associated motor will turn ONLY counter-clockwise.

The board is controlled by two transistors on the driver board. One transistor "enables" movement of the associated motor. The other determines whether the motor moves clockwise or counter-clockwise.

[[Image:A-15680Schematic.jpg|300px|thumb|left|Schematic for A-15680 Bi-Directional Motor Drive Board.]] 
 

====Double Flipper Opto Switch Board (A-15894) (Type I)====
[[File:Placeholder.jpg|300px|thumb|left|A-15894 Flipper Opto Board Mounted on the Cabinet Wall]] 
This board is used in early WPC games which used the Fliptronics II board starting with Doctor Who (please confirm first game).

Please note when testing these boards, the right flipper board has to be plugged in for the left board to function. This is due to the +12v and ground connections being daisy-chained through the right board PCB to the left board. The manuals will typically claim the opposite. And in some cases, the +12v is daisy-chained via the right opto board, while the ground is daisy-chained via the left opto board.

It is always best to check the wiring in the game. If two gray or orange wires are connected on one side of the cabinet, the +12v and / or ground are daisy-chained to the the opposite side.
 

====Flipper Opto Board Assembly (A-17316) (Type II)====
[[File:A-17316.jpg|300px|thumb|left|A-17316 Flipper Opto Board]] 
This board is used in later WPC games which used the Fliptronics II board starting with Indiana Jones (verify) and was used until Pinball 2000.
 

====HSII & CFTBL Triac board (A-13088-2)====
[[Image:WMS_A-13088-2_Triac_Board.JPG|300px|thumb|left|A-13088-2 Triac Board]] 
This board is used in High Speed 2: The Getaway (for the beacon motor), CFTBL (for the hologram motor), and Hot Shot (basketball redemption game). This triac board was also used in the System 11B game, Whirlwind, under board number C-13088. It was used to control the topper fan.

Since the board is single sided, fractured solder joints are frequently a problem with this board, especially at C1 for some reason. The other failure point on this board is the MOC 3031 otpoisolator.
 

==== 24 Inch Opto Board (A-15646) ====
[[Image:24InchOptoBoard.jpg|300px|thumb|left|WPC 24 Inch Opto Board as used on BSD and Shadow]] 
Note: This board is sometimes referred to as the "24 Switch Opto PC Board".

This board is used on Bram Stoker's Dracula to sense the "Mist Ball" and on Shadow to sense when the ball is at the bottom of the mini playfield. The board is also used in Star Wars: Episode 1, NBA Fastbreak, Judge Dredd, and Hot Shot (basketball redemption game). The usual problem with this board is that the large inductor (marked "106C" in the picture) vibrates off the board. The circuitry on this board is similar to a television remote control circuit. It senses a particular signal frequency.
 

====TAF & TAFG High Power Board (A-15139)====
[[File:WPC A-15139 High Power Board.JPG|300px|thumb|left|A-15139 High Power board as used in TAF and TAFG]] 
This board (aka magnet board) drives the three under playfield magnets used on The Addams Family and The Addams Family Gold. It is located under the bottom left of the playfield. 

====TAF & TAFG Extra Flipper Power Supply (A-15416)====
[[File:WPC A-15416 Extra Flipper PS.JPG|300px|thumb|left|A-15416 Extra Flipper Power Supply board as used in TAF and TAFG]] 
This board powers the upper flippers and the playfield magnets for The Addams Family and The Addams Family Gold. It is located just to the right and just above the driver board in the backbox. 
 
The schematics for this board are incorrect in the Addams Family manual. Specifically J903 is shown incorrectly. J903 Pins 1 and 2 supply 50v for the magnet board under the playfield. Pins 3 and 4 are ground for the magnet board under the playfield. The bridge rectifier diagram is also incorrectly rotated by 90 degrees. 

==== The Shadow Five Switch and Diode P.C.B. (A-13940) ====
[[File:TheShadowDiodeBoard.jpg|300px|thumb|left|This board was used only on "The Shadow" to provide lamp matrix diode isolation for the 4 "Ring Grain of Wheat" lamps, in-situ.]]
[[File:TheShadowDiodeBoardBare.jpg|300px|thumb|right|The bare board.]] 
This board was used only on "The Shadow" to provide lamp matrix diode isolation for the 4 "Ring Grain of Wheat" lamps. Yes, that's really it's name. 

====Coin Door Interface Board====
[[Image:CoinDoorInterfaceBoardAnnotated.jpg|300px|thumb|left|WPC/WPC-95 Coin Door Interface Board]] 
The coin door interface board provides signal connection between the coin door switches and the WPC switch matrix and dedicated switches like the "diagnostic" and volume control buttons. The coin door interface board also creates the "always closed" switch 24 by bridging column 2 and row 4 with a diode. WPC games use this "always closed" switch to identify switch matrix power issues.

If the coin door interface board gets dusty from flipper parts wearing, clean it. That dust is conductive and may cause odd coinage issues. There really isn't much that can go wrong with this board.
 

====WPC Alphanumeric Plasma Display Board====
[[Image:FHDisplayComponentSide.jpg|300px|thumb|left|The component side of the Funhouse / Bride of Pinbot WPC alphanumeric display.]]
[[Image:FHDisplayGlassSide.jpg|300px|thumb|right|The display glass side of the Funhouse / Bride of Pinbot WPC alphanumeric display.]] 
Funhouse and The Machine: Bride of Pin*Bot used dual 16-Alphanumeric displays, and a special (specific) high voltage power supply/logic board. The high voltage circuit is similar, if not identical, to late System 11 high voltage power circuits. 

Harley Davidson also used dual 16-alphanumeric displays, however, they were placed side by side on separate boards, instead of being "stacked" on one board.
 

====Scared Stiff Crate Board====
[[Image:ScaredStiffCrateBoard.jpg|300px|thumb|left|The "Scared Stiff" Crate Board]] 
This simple board mounts to the top of the Scared Stiff crate. It creates the "eyes" that look out the top of the crate. It contains 8 LEDs, 4 current limiting resistors, and 4 diodes, which isolate the LED "lamps" in the lamp matrix. Very little can go wrong with this board other than fractured solder joints, since it lives in a high vibration area of the game.
 

====DC Motor Control Board (A-16120)====
[[Image:A-16120DCMotorControl.jpg|300px|thumb|left|A-16120 DC Motor Control Board]] 
This board is used in Cactus Canyon, Demo Man, Monster Bash, No Good Gophers, The Shadow, Twilight Zone, Theater of Magic, World Cup Soccer.
 

====Bridge Driver PCB Assembly (A-15946)====
[[Image:A-15946DCMotorControl.jpg|300px|thumb|left|A-15946 Bridge Driver PCB Assembly]] 
This board is used in Indiana Jones and Hot Shots Basketball. The board is close in design to the A-16120 DC Motor Control Board (above). For Indiana Jones, it controls the Path of Adventure motor, which must turn both clockwise and counter-clockwise.

This simple assembly receives 12VDC power and ground, along with two solenoid connections to the driver board. Grounding one pin of the connection causes +12VDC to be output at the motor power pins. Grounding the other pin will cause -12VDC to be output at the motor power pins.

Indiana Jones uses solenoid 22 to move the POA left and solenoid 23 to move the POA right.
 

==== Indiana Jones Path of Adventure (POA) Opto Board ====
[[Image:IJPOAOptoBoard.jpg|300px|thumb|left|The Indiana Jones POA opto board. The optos are identical to those used on cabinet flipper switch opto boards.]] 
This simple board is used in Indiana Jones to provide "travel limit" feedback to the MPU for the POA. Typical problems include fractured solder joints, since the board experiences a lot of vibration from the POA motor, as well as simple opto failures.
 

==== Corvette Z5 Master (A-18532) and Slave Boards (A-19625)====
[[File:Bally Corvette A-18532 Motor Driver Master.jpg|300px|thumb|left|Bally Corvette A-18532 Motor Driver Master]]
[[File:Bally Corvette A-19625 Motor Driver Slave.jpg|300px|thumb|right|Bally Corvette A-19625 Motor Driver Slave]] 
This pair of boards work together to "rev" the ZR1 LT5 engine toy on the upper left side of the playfield. The master board senses the position of the motor unit using a Hall Effect sensor located below the engine toy assembly. The slave board uses 20V power and four TIP-102s to control four coils below the playfield on the ZR1 LT5 assembly.

Debugging information for the ZR1 LT5 assembly can be found [https://www.pinwiki.com/wiki/index.php?title=Corvette#LT-5_Engine_Electronics_issues here].
 

==== WPC A-13901 / A-17402-3 (and variants) Opto Ramp Switch Board (3 Opto Controller) ====
[[File:WMS A-17402 3-opto.jpg|300px|thumb|left|WMS 3 Opto Controller Board (as shown under playfield of Indiana Jones)]]
[[File:WMS A-13901 A-17402-3 Schems.png|300px|thumb|right|Schematics for A-13901 / A-17402-3 3 Opto Controller Board (*Note: R10 value was changed to correct 22K value in schems)]] 
There are several variations of the A-13901 / A-17402 3 opto controller board used on several games. Games such as Indiana Jones, CFTBL, Fish Tales, High Speed 2, Hurricane, Slugfest, Funhouse, and Hot Shot all used some version of this board. The part numbers used are:
*A-13901-1-AI
*A-13901-1
*A-13901-2
*A-13901-3
*A-13901-AI
*A-13901
*A-17402-3
 

==== WPC A-19043-1 Stepper Motor Driver Board ====
[[File:A19043-1.jpg|300px|thumb|left|WMS Stepper Motor Driver Board)]]
[[File:Placeholder.jpg|300px|thumb|right|Schematics for A-19043-1 Stepper Motor Driver Board]] 
The Stepper Motor Driver Board is used only in WhoDunnit (Slot Machine Reels). Three of these boards are used to drive the three slot machine reel stepper motors.
 

==== Coin Doubler Board ====
[[Image:WPCCoinDoublerInSitu.jpg|300px|thumb|left|An Aftermarket "Coin Doubler" Board, shown attached to a WPC MPU.]] 
This aftermarket add-on board connects atop the direct switches connector on the WPC MPU. It intercepts the coin switches and, for each switch closure it sees, sends the computer two closures. This "hack" effectively halves game pricing. This was done because Williams removed the one-coin-per-play pricing for some games to try and force a price increase.

These are still for sale from [https://gameboardsusa.com/shop/ols/products/coin-doubler-board-for-wpc-games-turns-50-cent-play-into-25-cent-play Game Boards USA].
 

===Flipper Coils===

WPC games use different flipper coils dependent on flipper placement and application. Below is a chart of the flipper coils used, their wrapper color, and strength.

{| class="wikitable"
!colspan="4" |WPC Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||
|-
|FL-20867 || White || See notes || Used only in Safecracker
|-
|FL-11630 || Red || Standard ||
|-
|FL-15411 || Orange || Stronger ||
|-
|FL-11629 || Blue || Strongest ||
|}

Notes:

The FL-20867 flipper coil (white wrapper) was used only on Safecracker. The FL-20867 flipper coil is thought to be between an FL-11722 and an FL-11630 in strength.

Williams also produced an FL-17636 flipper coil (blue wrapper) for use in Star Trek: The Next Generation. This coil is somewhat stronger than the FL-11629, and was used on the prototype games - and some number of production games - to facilitate shots to the Delta ramp. At some point during the ST:TNG production run Williams switched back to FL-11629 coils, perhaps because the Delta ramp shot can be made with an FL-11629 coil with new condition flipper mechs, or due to operator reports of breakage. Still, a large number of games seem to show up with FL-17636 coils, leading one to suspect operators may have swapped out the FL-11629 coils to the stronger FL-17636 coils as the flipper mechs wore. (There is probably an increased chance of breaking playfield plastics and other parts with the FL-17636 coils in place.)

[[File:ParallelCoilWindings.jpg|300px|thumb|left|Note the windings of this typical WPC coil. The larger wire is the high power winding, the smaller wire is the hold winding. Both wires are soldered to the lug on the left.]] 

===WPC Transformers===

{| class="wikitable"
|+Transformers
!| Part Number    || Description           || Distinguishing Features || Games
|-
|5610-12718-00 || WPC, 115/230v || (18VAC sound) alphanumeric || BoP, FH, HD
|-
|5610-12835-00 || WPC3, 115/230v || (18VAC sound) || BoP, BR, BSD, CFTBL, DW, FH, FT, GI, HD, HS2, Hot Shots Basketball, Hurricane, PZ, Slugfest, T2, TAF, TAFG, TZ, WH2O
|-
|5610-13491-00 || WPC Power || (12VAC sound) || IJ, JD, Pinball Circus, Popeye, STTNG
|-
|5610-13953-00 || WPC94 || (female line input) || Corvette, DH, DM, FS, RS, Shadow, WCS
|-
|5610-14515-00 || WPC Wide Mount || || AFM, Congo, I500, JB, JM, NF, SC, SS, ToM, TOTAN, WD
|-
|5610-14515-01 || WPC Wide Mount || || AFM, CC, CP, CV, Congo, I500, JB, JM, JY, MB, MM, NBA, NF, NGG, SC, SS, ToM, TotAN, WD
|-
|5610-15930-00 || transformer p2000 || || RFM
|-
|5610-15930-01 || transformer p2000 || || SWE1
|}

====Primary Voltage Selection Jumpers at the Transformer====
On all WPC games, there are either a 9 pin or 12 pin Molex connector used to change the primary voltage setting fed to the transformer. 9 pin connectors were connected to a pigtail off the transformer itself. Later units used a 12 pin connector on the power source metal box located inside the cabinet floor on the right just inside the coin door. Depending on the placement of the jumpers, common configurations are 115v (typical domestic setting), 230v (European setting), and 100v (Japanese setting). 

It is common to change the voltage setting (220 to 120 volt conversion) if a game is re-imported back into the US. Although probably more common at the moment is to convert a domestic game to 220 volts (more games are currently being exported from the US than imported).

All voltage selection pins are .093 molex pins. Removal of the pins requires a special molex tool. See [http://www.pinwiki.com/wiki/index.php?title=General#Headers.2C_Housings.2C_and_Crimping "Headers, Housing, and Crimping].

'''Important Notes:'''
#When jumpered for 120V operation, the line fuse is an 8ASB, and a 130V Varistor is used.
#When jumpered for 230V operation, the line fuse is a 5ASB, and a 260V Varistor is used.
 

====Early WPC Transformers (9 pin connection)====
The 9 pin connectors used are Molex 19-09-2099 (butterfly connection w/jumpers) and Molex 19-09-1099 (connection on transformer pigtail).
[[File:WPCPowerSelectButterfly.jpg|300px|thumb|left|9 Pin WPC Transformer Power Configuration, configured for US 115V systems.]] 
Jumper settings for 115V should be as follows:
*Pin 1 - black - 115v "hot" input
*Pin 7 - white - 115v "neutral" input
*Pins 2 and 3 jumped together
*Pins 8 and 9 jumped together
 

[[File:230VLineVoltageConfiguration.jpg|300px|thumb|left|9 Pin WPC Transformer Power Configuration, configured for 230V systems.]] 
Jumper settings for 230V should be as follows:
*Pin 1 - black - 230v "hot" input
*Pin 7 - white - 230v "neutral" input
*Pins 3 and 9 jumped together
 

====Later WPC Transformers (12 pin connection)====
[[File:Plug2.JPG|300px|thumb|left|12 Pin WPC Transformer Power Configuration, configured for US 120V systems]]
[[File:Plug1.JPG|300px|thumb|right|12 Pin Connector as Found inside later games]] 
'''Jumper settings for 120v should be as follows:'''
*Pins 1 and 11 jumped together
*Pins 2 and 3 jumped together
*Pins 7 and 10 jumped together
*Pins 8 and 9 jumped together

The 12 pin connector used is Molex 19-09-1129.
 

[[File:WPCEuropeanPowerSelectSascha12Pin.jpg|300px|thumb|left|12 Pin WPC Transformer Power Configuration, configured for European 240V systems]] 
'''Jumper settings for 240V should be as follows:'''
*Pins 1 and 11 jumped together
*Pins 7 and 10 jumped together
*Pins 3 and 9 jumped together
 

===Unused Connectors===
[[File:FactoryTestConnectorOrDeletedFeature.jpg|300px|thumb|left|An example of a "leftover connector". This one appears on "No Fear".]] 
Some WPC games have connectors in the backbox or under the playfield that are unused in the production configuration. These connectors were originally installed to support features that were deleted when the game went to production or perhaps were installed as test connectors that could be used during assembly to ensure all features were operating correctly.
 

==Problems and Solutions==
=== Jumpers, RAM and ROM size ===
[[Image:WPC089Jumpers.jpg|300px|thumb|left|Closeup of WPC-089 MPU that uses a 6264 RAM and a 4M game ROM. Note jumpers W1, and W2 to set ROM size as well as W3 (out) and R93 (in) to set RAM size.]]
[[Image:WPC089MPUwith62256RAM.jpg|300px|thumb|Right|Closeup of WPC-089 MPU that uses a 62256 RAM and a 4M game ROM. Note jumpers W1, and W2 to set ROM size as well as W3 (in) and R93 (out) to set RAM size.]]

RAM Size 
The WPC-089 MPU can be configured for two different RAM sizes. This is done with jumper W3 and resistor R93 as shown below.
*6264 RAM - W3 out, R93 in (a 1.5K 1/4W resistor)
*62256 RAM - W3 in, R93 out
Both RAM sizes work fine in all games. Williams probably provided this flexibility to allow use of whichever RAM was cheaper or more available. Note: Most NVRAM replacements are 6264 replacements.

[[Image:WPC95RAMSizeJumper.jpg|300px|thumb|left|Closeup of WPC-95 MPU that uses a 62256 RAM. Note jumper W3 is installed to set the RAM size for a 62256 RAM.]]

The WPC-95 MPU can be configured for two different RAM sizes. This is done with jumper W3 (only) as shown below. R93 is always installed.
*6264 RAM - W3 out
*62256 RAM - W3 in
Again, both RAM sizes work fine in all games and most NVRAM replacements are 6264 replacements.
 

ROM Size 
The MPU can also (and needs to be) jumpered for different ROM sizes. This becomes important when upgrading ROMs or swapping a CPU (and ROM) into a different game. Games like Funhouse shipped with a 1M ROM, jumper W2 in, and jumper W1 out. Updating the Funhouse ROM to a larger size ROM requires W1 in and W2 out.

The official Williams ROM size/jumper settings are shown below.
* 512K/1M - W1 out, W2 in
* 2M/4M - W1 in, W2 out
 

===Test ROMs===
Test ROMs are available from [http://www.planetarypinball.com/mm5/Williams/tech/testroms.html Planetary Pinball], but they should only be used in conjunction with a [http://pinballrehab.com/1-articles/solid-state-repair/board-rework-test/243-building-a-wpc-test-fixture test fixture] and not installed in an actual game, as per the official recommendation.

=== Country DIP Switch (or jumper) Settings ===
[[File:WPCCountryCodeJumperMessage.jpg|300px|thumb|left|Country Code Jumper message.]] 
The message shown at left occurs sometimes when the game software seems to want the "country code" jumpers to be configured in a certain way. The simple solution (for English speaking users) is to remove the jumpers noted in the message by cutting them off. This sets the board to "AMERICA2". Twilight Zone, and perhaps game ROM version 9.4H, seem to prefer the "AMERICA2" country code. Other country code jumper configurations are shown below.
 

[[File:WPCCountryCodeJumpersExample.jpg|200px|thumb|left|Two WPC-089 MPUs, one configured with DIP switches, the other with "zero ohm resistors" (jumpers).]] 
Two WPC-089 MPUs are shown at left. Early versions of the MPU used "zero ohm resistors" or jumpers to figure the country code. Later versions of the MPU (as well as WPC-S and WPC-95 MPUs, used DIP switches. 

Note: If a dip switch is installed, always leave W11 and W12 in the OFF position. If both are set on ON, the undervoltage detection circuit on the WPC Power/Driver will not work and both LED2 and LED3 will always remain on.
 

[[File:WPCCountryCodeJumperTable.jpg|400px|thumb|left|WPC-089 Country Code Jumper Table]] 
The complete WPC-089 country code jumper table is shown at left.
 

[[File:WPC95CountryCodeJumperTable.jpg|400px|thumb|left|WPC-S/WPC-95 Country Code Jumper Table]] 
The complete WPC-S/WPC-95 country code jumper table is shown at left. WPC-S/WPC-95 MPUs do not have an "AMERICA2" configuration.
 

===Power-On LEDs and Sound Tones (Bongs)===
When the game is booted, several LEDs in the backbox will light, and the game may provide sound "bongs" to indicate diagnostic status.

A properly booting WPC game will show a "progress bar" on the DMD along with a "ticking" sound which results from a series of reset signals being sent to the sound board. After a successful boot, the sound board will create a single "bong" tone.

==== LEDs on the MPU ====

Note: WPC and WPC-S games label the MPU and Power/Driver board LEDs as "Dxx". WPC-95 games label these same LEDs "LEDxxx".
*D19 (LED201) - "Blanking". This LED should light when power is applied, then after about 1 second, go off and stay off. If D19 remains on, this is an indication that the blanking circuit is turned on which prevents the game from powering coils. The blanking circuit was implemented to eliminate the possibility of damaging the game due to locked on coils when the CPU isn't operating properly.
*D20 (LED203) - "Diagnostics". Once the blanking LED turns off, this LED should begin blinking and remain blinking as long as the game is turned on. This LED is a simple "I'm working" indication from the MPU. This LED is toggled from pin 35 of the ASIC (DLED signal). D20 will also indicate basic issues with the MPU by blinking as such...
**One blink - problem with the game ROM.
**Two blinks - problem with the game RAM (or accessing the RAM, i.e. open traces).
**Three blinks - problem with the ASIC (WPC) or a problem with the security chip (WPC-S and WPC-95).
*D21 (LED202) - "5VDC present". This LED provides a simple indication of the presence of 5VDC. This LED isn't CPU controlled. It's illuminated as long as 5VDC is present.

[[image:YT.png]] A YouTube video of an MPU blinking D20 twice, indicating a RAM issue, can be found [https://youtu.be/7ZEYIVXgDTo here].

'''Note:''' It is possible for the switch column IC, U20, to be blown and the damage continuing upstream to U14. In this case, it is possible that the data signals become corrupt and prevent the MPU from booting. D19 and D21 will light but D20 will never light.

[[File:WPCLEDBehavior.jpg|800px|thumb|left|Graphic provided by Ingo Kramer. Used with permission.]] 
[[File:WPCLEDBehaviorUpdated.gif|800px|thumb|left|Graphic provided by Sascha Voksuil. Used with permission.]] 
 

==== LEDs and test points on WPC-089 Power/Driver Boards ====

{| class="wikitable"
! LED/Test Point 
!Explanation
|-
|<center> '''LED1-TP3''' </center> || Normally lit. Indicates presence of regulated 12VDC (12VR). AC voltage is rectified to about 18VDC by BR1 and smoothed by C6 and C7 (this power is tapped for the lamp matrix). D1 and D2 are used to drop the voltage by 1.0 to 1.4V and then the voltage is further regulated down by the LM7812 at Q2. This 12VDC power is shown as "+12V Digital" on the schematics. This power is fused by F114. If LED6 isn't lit, LED1 won't be lit either.
|-
|<center> '''LED2-no TP''' </center> || If installed, provides an indication of high/low line voltage. This LED isn't very useful as it will flicker as power consumption by the game fluctuates.
|-
|<center>  '''LED3-no TP'''  </center> || If installed, provides an indication of high/low line voltage. This LED isn't very useful as it will flicker as power consumption by the game fluctuates.
|-
|<center> '''LED4-TP2''' </center> || Normally lit. Indicates presence of regulated 5VDC. AC voltage is rectified by BR2 and smoothed by C5. The voltage is regulated down by the LM323K at Q1. This 5VDC power is shown as "+5V Digital" on the schematics. This power is fused by F113.
|-
|<center> '''LED5-TP7''' </center> || Normally lit. Indicates presence of unregulated 20VDC. AC voltage is rectified by BR4 and smoothed by C11. The voltage is used to power the flash lamps. Note that beginning sometime during production of Twilight Zone in 1993, a "coin door interlock" switch was added. This switch interrupts power to both the 20VDC and 50VDC circuits when the coin door is opened, providing a measure of safety against higher voltage shocks. If the coin door is opened with power applied, this LED will fade to off. It will not light with the coin door open. This power is fused by F111.
|-
|<center> '''LED6-TP8''' </center> || Normally lit. Indicates presence of unregulated 18VDC. AC voltage is rectified to about 18VDC by BR1 and smoothed by C6 and C7. This 18VDC power is used to power the lamp matrix lamps. This power is fused by F114.
|-
|<center> '''LED7-TP1''' </center> || Normally lit. AC voltage is rectified to about 12VDC by BR5 and smoothed by C30 to provide unregulated 12VDC power. This 12VDC power is shown as "+12V Power" on the schematics. It is used to power motors, optos, and other game features that do not require a precise 12VDC. This power is fused by F116.
|-
|<center> '''TP4''' </center> || Zero Cross. By using an oscilloscope, this test point allows testing of the "zero cross" circuitry. "Zero cross" is when the AC sine wave crosses through the zero voltage point relative to ground. Zero cross is important for the proper operation of the general illumination lamp circuit.
|-
|<center> '''TP5''' </center> || Ground. This test point stud may be used to measure all DC voltages against.
|-
|<center> '''TP6''' </center> || 50VDC power. This test point will actually measure 70 - 75VDC, which is normal and expected. This power is used for all coils in the game including the flippers. This power is fused by F112. Individual coil power circuits are fused by F101 thru F105. F112 protects both BR3 and the bridge rectifier circuit on the FlipTronic II board. Should F112 blow, remove J104 (or J105). Replace the fuse. Power on. If the fuse blows, BR3 has probably failed. If it holds, the bridge rectifier on the FlipTronics II board has probably failed.
|}

[[File:WPC089 power summary.png|800px|thumb|center|Summary schematic of WPC-89 Power Driver board showing test LED's and test points. A PDF of this image can be viewed [[Media:WPC089 power summary.pdf|here]]]]
 

==== LEDs and test points on WPC-95 Power/Driver Boards ====

{| class="wikitable"
! LED/Test Point 
!Explanation
|-
|<center>  '''LED100-TP100'''  </center> || Normally lit. Indicates presence of regulated 12VDC. AC voltage is rectified to about 18VDC by D11-D14 and smoothed by C11 and C12. D1 and D2 are used to drop the voltage by 1.0 to 1.4V and then the voltage is further regulated down by the LM7812 at Q2. This 12VDC power is shown as "+12V Digital" on the schematics.
|-
|<center> '''LED101-TP101''' </center> || Normally lit. Indicates presence of regulated 5VDC. AC voltage is rectified by D7-D10 and smoothed by C9. The voltage is regulated down by the LM317K at Q1. This 5VDC power is shown as "+5V Digital" on the schematics.
|-
|<center> '''LED102-TP102''' </center> || Normally lit. Indicates presence of unregulated 18VDC. AC voltage is rectified to about 18VDC by D11-D14 and smoothed by C11 and C12. This 18VDC power is used to power the lamp matrix lamps, and is subsequently regulated to 12V for use in the switch matrix.
|-
|<center> '''LED103-TP103''' </center> || Normally lit. AC voltage is rectified to about 12VDC by D3-D6 and smoothed by C8 to provide unregulated 12VDC power. This 12VDC power is shown as "+12V unreg" on the schematics. It is used to power motors and other game features that do not require a precise 12VDC.
|-
|<center> '''LED104-TP104''' </center> || Normally lit. Indicates presence of unregulated 20VDC. AC voltage is rectified by D15-D18 and smoothed by C10. The voltage is used to power the flash lamps. Note that a "coin door interlock" switch is present on all WPC-95 games. This switch interrupts power to both the 20VDC and 50VDC circuits when the coin door is opened, providing a measure of safety against higher voltage shocks. If the coin door is opened with power applied, this LED will fade to off. It will not light with the coin door open.
|-
|<center> '''LED105-TP105''' </center> || Normally lit. Indicates presence of unregulated 50VDC. This test point will actually measure 70 - 75VDC. This power is used for all coils in the game. AC voltage is rectified to about 75VDC by D19-D22 and smoothed somewhat by C22.
|-
|<center> '''TP106''' </center> || Zero Cross. By using an oscilloscope, this test point allows testing of the "zero cross" circuitry. "Zero cross" is when the AC sine wave crosses through the zero voltage point relative to ground. Zero cross is important for the proper operation of the general illumination lamp circuit.
|-
|<center> '''TP107''' </center> || Ground. This test point stud may be used to measure all DC voltages against.
|}
[[File:WPC095 power summary.png|800px|thumb|center|Summary schematic of WPC-95 Power Driver board showing test LED's and test points. A PDF of this image can be viewed [[Media:WPC089 power summary.pdf|here]]]]

==== Power on Sound Tones (Bongs) ====

After a successful boot, the game should make a single "bong" sound. The game provides a sound board problem indication with the following number of bongs.

Pre-DCS Sound Board Games.
*1 - No issues...enjoy a game.
*2 - U9 RAM failure.
*3 - U18 ROM failure.
*4 - U15 ROM failure.
*5 - U14 ROM failure.

DCS Sound Board Games.
*1 - No issues...enjoy a game.
*2 - U2 ROM failure.
*3 - U3 ROM failure.
*4 - U4 ROM failure.
*5 - U5 ROM failure.
*6 - U6 ROM failure.
*7 - U7 ROM failure.
*8 - U8 ROM failure.
*9 - U9 ROM failure.
*10 - U10-U12 RAM failure. Note: DCS sound board RAM failures are indicated by a message on the display, "U10-U12 RAM error".

Audio/Video Board Games (WPC-95).
*1 - No issues...enjoy a game.
*2 - S2 ROM failure. Note: Two bongs also occur if jumper W3 is IN, and the RAM size is 6264. If an NVRAM was just installed, check this jumper. See the section on [[Williams_WPC#Jumpers.2C_RAM_and_ROM_size | jumpers]].
*3 - S3 ROM failure.
*4 - S4 ROM failure.
*5 - S5 ROM failure.
*6 - S6 ROM failure.
*7 - S7 ROM failure.
*10 - U9, U10, or U11 RAM failure (see below)

[[File:WPC95U9-U11Error.jpg|200px|thumb|left|WPC-95 boot time RAM error message, accompanied by 10 very annoying bongs.]]
[[File:WPC95U10U12Message.jpg|200px|thumb|right|WPC-95 boot time RAM error message, accompanied by 10 very annoying bongs.]] 
A/V sound board RAM failures are indicated by a message on the display, either "U9-U11 RAM error" or "U10-U12 RAM error". This is apparently game software dependent. A/V RAM are, in fact, U9-U11. Apparently, this message wasn't updated in the software with the introduction of the A/V board. 

===Fuses===

Fuses are used to protect the various game circuits when a problem arises and the circuit begins to draw more current than originally designed to draw.

The best way to test a fuse is to remove it from it's fuse holder and "buzz" it with a DMM set to continuity. This method will prevent false positives via "sneak circuits". When removing fuses from a RottenDog aftermarket power/driver board should be done with extreme care as the fuse clips are easily bent and damaged.

====WPC/WPC-95 Fuse Tables====

[[File:WPCFuseList.jpg|200px|thumb|left|WPC Fuse Table from Twilight Zone.]]
[[File:WPC95FuseList.jpg|200px|thumb|right|WPC-95 Fuse Table from Monster Bash.]] 
A typical WPC fuse table is shown at left, WPC-95 fuse table at right.
 

==== F111 Blows, Testing BR4 With Board Still Installed====

[[File:TestingWPC-BR4-InSitu.gif|200px|thumb|left|Click this image for an animation showing how to test BR4 without removing the power/driver board. Animated gif provided by Sascha Voksuil, aka PinSider ZaZa. Used with permission..]] 
Fuse F111 sits between the transformer secondary and BR4. BR4 recitifies AC power for the flash lamps. If BR4 failes shorted, F111 will blow, protecting the transformer secondary winding.

BR4 can be tested "in situ" using the method shown in the animated gif at left. 
Note: This test requires a good fuse to be in place at F111 for the test to work properly.
 

===Testing DC Voltages on the Power/Driver Board===
[[File:YT.png]] A YouTube video showing how to test each of the voltages on the WPC-089 Power/Driver board can be found [https://www.youtube.com/watch?v=uz6bnFiCki0&lc=UgwKkBxANoJnz3Xjr3Z4AaABAg here].

===Removing or Installing the ASIC===
[[File:ASICRemovalTool.jpg|200px|thumb|left|Using a PLCC puller to properly remove the ASIC. Grip firmly, and "rock" the chip out gently.]] 
Should ASIC need to be removed from a WPC MPU, it is strongly advised that tthe proper tool is used, as shown at left. The tool is called a PLCC puller. 
[[File:YT.png]] A video showing the proper technique for removing the WPC ASIC can be found [https://www.youtube.com/watch?v=qKmlsTlagfg here].
 

[[File:DamagedWPC-ASIC.jpg|200px|thumb|left|This ASIC was damaged by not using the proper removal tool.]]
[[File:WPCCrackedASICSocket.jpg|200px|thumb|right|This cracked ASIC socket caused intermittent operation of the game.]] 
Using a jewelers screwdriver or other such tool can fracture the ASIC chip carrier socket as shown at right. Since these are 84 pins sockets, replacement is non-trivial. Using the incorrect tool may also irreparably damage the ASIC itself by permanently fracturing leg joints, as shown at left.
 

[[File:WPC89ASICOrientation.jpg|200px|thumb|left|Correct orientation relative to the PLCC socket, shown here for a WPC-089 or WPC-S MPU board.]] 
The ASIC must be oriented correctly when installed. Pin 1 of the ASIC is marked with a dot impression on the top of the chip. Pin 1 of the PLCC socket is marked with an arrow pointing to pin one. This is true for all versions of WPC MPUs. Orient the ASIC as shown in the picture at left relative to the arrow in the socket, center the chip over the socket, and press firmly on the chip center.
 

=== WPC ASIC Pinout ===
[[File:ASICIcon.jpg|200px|thumb|left|WPC ASIC pinout and board connections|link=https://www.pinwiki.com/wiki/index.php?title=File:WPCASICPinOutRevisionA.pdf]] 
Clicking on the thumbnail at left will open a .pdf file containing pin connections for the WPC (in work) and WPC-S MPUs.
 

[[File:ASICPinOutSmall.jpg|200px|thumb|left|WPC ASIC pinout and board connections|link=https://www.pinwiki.com/wiki/images/e/e1/WPCASICPinoutviaZaza.jpg]] 
Clicking on the thumbnail at left will open a .pdf file containing a graphic image of the ASIC pinout, ''provided courtesy of Sascha Voskuil''.
 

===Game blows power line circuit breaker immediately===
[[File:WPCPowerBoxInside.jpg|200px|thumb|left|Underside of power box showing varistor and thermistor]]
Had a thunderstorm roll through or a power surge from the electric company recently?
The varistor in the power box may have done it's job protecting the rest of the game's circuitry from the possibly tremendous power surge. 

Signs of a failed varistor are typically black, charred discoloration throughout the "button" portion (green in the case of the adjacent picture) of the varistor. Likewise, varistors can blow rather violently, and there may be charred or burnt remains in the area surrounding the varistor. 

Over time, the rating of a varistor will lower, causing "occasional" blowing of the mains fuse. The varistor will visually appear to be OK. A good hint is how violently the fuse blows. Likely varistor problems will cause the fuse to totally obliterate.

Varistors can be purchased from [https://www.greatplainselectronics.com/products.asp?cat=76 Great Plains Electronics]. Order the 130V variant for 120VAC (typically games in the US), and the 275V variant for 240VAC (typcailly games in Europe).
 

===Credit Dot===
[[file:Credit dot sttng.jpg|200px|left|thumb|Example credit dot on Star Trek The Next Generation]] 
The credit dot is a decimal point (a single, lit pixel on the display), that appears after the number of credits or after the words free play on the DMD display on WPC games. It is a quick indicator used to tell the operator or owner that there may be an issue with the game. Most commonly, there is a switch or multiple switch problems with the game. However, a credit dot will appear for other reasons, such as when the date and time are not set. 

If, after 30 balls or 10 games, a particular switch hasn't registered, the credit dot is posted to alert the user to check the diagnostics. Some high usage switches will trigger the alert earlier. The credit dot may or may not indicate a real problem. For the example shown in the pic, it's simply reporting a switch that is hard to hit in the game. So, the credit dot is actually saying "Play Better". :-)
 

===Battery Issues===

====Relocating the battery from the MPU board====
[[File:WPC CPU Bat Damage.JPG|left|thumb|200px|An example of worse than usual battery damage]] 
Relocating the 3xAA battery pack from the MPU board is always a good idea. Leaky alkaline batteries are the #1 killer of MPU boards. Simply removing the batteries is not an option with WPC games as a message stating "Factory Settings Restored" will be received when the game boots.
 

There are several options other than allowing the battery pack to remain on the MPU board. Below are the two most common methods. 

The first, most common, and most economical option is to remotely locate the battery holder off the MPU board and somewhere below all other boards. This ensures that even if the remotely located batteries leak, they won't leak onto (or even drip onto) any circuit board. Replace the batteries annually, dating them with a Sharpie. Connections are as follows. With the CPU oriented as it would be in the game, solder the red (positive) wire to the upper right battery pack position. Solder the black (negative) wire to the lower left battery pack position. Note: most battery packs do not come with wire leads long enough to allow the battery pack to rest in the backbox bottom. Lengthen the wires as necessary. As can be viewed in the adjacent picture, a male / female .093" Molex connector was added to easily remove the battery pack from the MPU board should the need arise.
<center>
<gallery widths=200px heights=200px perrow=3 caption="WPC, WPC-S, and WPC-95 Remote Battery Holder Connections.">
File:WPC MPU Battery Relocate.JPG|<center>WPC-089</center>
File:WPC-SMPUBatteryConnections.jpg|<center>WPC-S</center>
File:WPC95RemoteBatteryHolder.jpg|<center>WPC-95</center>
</gallery>
</center>
 

====Installing an external battery on a WPC-95 CPU using the Auxiliary Battery header (J213)====
[[File:WPC95AuxBatteryHeader.jpg|200px|thumb|left|Installed Remote Battery Connector]]
[[File:WPC95RemoteBatteryOption.jpg|200px|thumb|right|An alternate, but equivalent method. Positive and Negative are clearly labeled.]] 
The WPC-95 CPU board has an unused external battery connector just above the battery holder. The connector is labeled J213 AUX BAT. The 4 pads can be seen in the above picture of the CPU with the old holder removed. Installing this 4-pin connector is a good and clean way to get the batteries off the board and prevent alkaline damage. The Molex part number for the C-Grid® SL™ 70543 4 pin connector is 70543-003 (Digikey WM4802-ND). Crimp pins for the female side are 16-02-1125 (WM2573-ND) and the housing is 50-57-9404 (WM2902-ND). The WPC-S CPU uses a 5 pin version of this connector.
 
Warning: Do not use both the internal and external connector at the same time. Doing so will likely damage the batteries.
 

====Settings Not Held or Battery Depletes Rapidly====
[[File:WPC MPU D1 D2.JPG|left|thumb|200px|A WPC MPU board with D1 and D2 circled. D1 and D2 are in the identical location on the WPC-S MPU]]
[[File:WPC-95MPUD1D2.jpg|right|thumb|200px|A WPC-95 MPU board with D1 and D2 shown in the middle of the picture, just below the battery holder]]
During the process of installing a remote battery holder, it is a good practice to check the diodes utilized in conjunction with the battery power. Diode D2, a 1N4148, is used to keep the MPU board's logic power from charging the batteries in the battery pack. Diode D1, a 1N5817, is used to keep the battery pack from powering the entire MPU board when the games's power is turned off. 
*If D2 fails shorted, 5VDC power will be applied to the batteries while the game is turned on. The end result is batteries which die prematurely, possibly leak, and/or possibly explode (alkaline batteries do not like to be charged).
*If D2 fails open, the batteries will not power the static RAM, and the "FACTORY SETTINGS RESTORED" message will be displayed when the game boots.
*Should D1 fail, the batteries would more than likely just deplete prematurely.
 

[[File:TestingForPowerAtRAM.jpg|left|thumb|200px|Probing pin 28 of the WPC-95 MPU RAM IC for Vbb (battery backup power)]]
[[File:6264RAMPinout.jpg|right|thumb|200px|Pinout of the 6264 RAM. Note Vcc, upper right, pin 28]] 
Testing to see if battery backup power is reaching the RAM with sufficient voltage is easy.
*Set your DMM to DC Voltage
*Connect the black probe to game ground (in the picture at left, a clip lead is attached to the ground screw)
*Use the red lead to probe pin 28 of the RAM
Measuring in this way should yield over 3.5 VDC. If measuring shows 0 VDC, either the batteries are dead, or D2 has failed (see above).

Ideally, this measurement should yield 1.5 VDC * 3 - .6 VDC = 3.9 VDC. This calculation represents the nominal voltage delivered by a single AA battery, times 3 (batteries), less a typical .6 VDC drop across diode D2. Remember that nominal voltage drop across a typical diode is .5 to .7 VDC.
 

===Replacing the CPU RAM with non-volatile RAM===
[[file:WPCR93.jpg|300px|left|thumb|A WPC-089 MPU board with 6264 RAM, jumper W3 removed, and R93 in place.]] 
A second option is to replace the 6264 static RAM with an NVRAM such as the RAMTRON FM1608 (or FM16W08). NVRAMs in the standard DIP package are becoming hard to find but several pinball parts vendors sell a nice 6264 replacement NVRAM based on these parts.

This method requires desoldering the OEM RAM from the board, and installing a socket on the MPU. Using NVRAM also has the down-side of not maintaining the Real Time Clock. This is meaningless in some games. But some games use the Real Time Clock, like Twilight Zone which moves the playfield clock to the current time of day during attract mode, and Who?Dunnit which has a "Midnight Madness" feature. Note: the WPC MPU is designed to accept either a 6264 or a 62256 static RAM. See: [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Jumpers.2C_RAM_and_ROM_size Jumpers, RAM and ROM size] for a description of jumpers required when installing a new RAM or NVRAM.
 

====Special note Concerning Early RottenDog WPC-TH MPUs and NVRAM====
[[file:EarlyRDMPU.jpg|300px|left|thumb|A RottenDog WPC-TH MPU. Note PCB date code of "0701", circled in yellow.]]
Most RottenDog MPU boards shipped with a 62256 RAM installed vs the 6264 RAM typically installed in Williams OEM boards. Early versions of the RottenDog board marked with "0701" on the silkscreen, as pictured at right, require the use of a 62256 NVRAM. The reason for this is that the address lines to the RAM position are not JEDEC "standard". Pins 9 and 10 (normally A0 and A1) are tied to ground as can be seen in the image at left. Clearly this scheme will not work with a standard 6264 pinout. But with a 62256, which has two extra address lines mapped as they are on the RottenDog board, will work perfectly fine. 
<gallery widths=200 heights=400 class=center>
File:RD62256NVRAM.jpg ‎| A RottenDog WPC-TH OEM installed 62256 RAM
File:RD62256Socket.jpg ‎| The RottenDog WPC-TH MPU RAM position. Note connection between pins 9, 10, and 14 (ground), which corresponds to the Cypress 62256 RAM pinout.
File:CypressCY62256.jpg | The pinout of the Cypress 62256 RAM, which matches the PCB design of the WPC-TH board
</gallery>
 

=== Repairing Alkaline Corrosion ===
[[file:WPCCorrosion.jpg|200px|left|thumb|A WPC-089 MPU board, after a couple hours of alkaline corrosion abatement.]]
[[file:AlkalineCorrosionCleanupWithLampSocketCleaner.jpg|200px|right|thumb|Using a "lamp socket cleaning stick" for precision removal of alkaline corrosion. These can be acquired at The Pinball Resource.]] 
Alkaline damage abatement on WPC MPUs is generally more difficult than Bally -17/-35 or Stern MPU-100/200 or Gottlieb System 80 MPUs. The traces on WPC MPUs are finer, and more abundant than on any of those boards. And, the "banks" of resistors and ceramic capacitors below the ULN-2803 and LM339s provide numerous hiding places for alkaline damage. The small traces under these components implement the switch matrix on the game.

If alkaline abatement is attempted, and if the ULN-2803 or LM339s are damaged, using any technique other than cutting them off the board, heating the alkaline damaged pads, and pulling the leftover legs out, WILL damage the board further. The alkaline adheres to the component legs and through-holes very strongly, making it near impossible to remove the component using typical desoldering tools, no matter how skilled the individual is.

As is normally done during this process, sand with fine grit sandpaper (or use an abrasive stick as shown on the right for precision work) until bare copper can be seen, treat the board with 50/50 white vinegar/water to neutralize the alkaline, then rinse thoroughly with isopropyl alcohol or other favorite cleaner. Re-tin the exposed traces.
 

<center>
<gallery widths=200px heights=200px perrow=3 caption="Replacing an Alkaline Corroded LM339 on a WPC-089 MPU">
File:LM339-1.jpg|<center>A corroded LM339</center>
File:LM339-2.jpg|<center>After cutting one side off, then bending repeatedly to break the other side off</center>
File:LM339-3.jpg|<center>Socket installed. All done</center>
</gallery>
</center>

[[file:RottenDogAlkalineCorrosion.jpg|200px|left|thumb|A Corroded WPC-089 Aftermarket RottenDog MPU board.]] 
The RottenDog WPC-089 MPU board pictured at left is an extreme example of corrosion creep. Corrosion moved all the way up the remote battery holder wires and onto the MPU. Abating alkaline corrosion on RottenDog MPUs is particularly difficult as the traces and vias are very, very small.
 

'''WPC-95 MPU Alkaline Corrosion Zone''' 

[[file:WPC95MPUCorrosionAreaParts.jpg|300px|left|thumb|Part identification in the WPC-95 MPU corrosion zone.]] 
Williams located the batteries for the WPC-95 MPU in an even worse location than on WPC-089 and WPC-S boards. With the batteries located above the ASIC socket, there is a substantial probability that severe damage could occur from leaky batteries. The usual alkaline abatement process should be followed.

'''Key:''' 

   Resistors - Blue 
   Capacitors - Yellow 
   Diodes - Red 
   Integrated Circuits - Green 
   Headers/Jumpers - Black 

Note that at least two revisions of the WPC-95 MPU board were produced, each with a slightly different part layout.
 

=== Slam Tilt ===

[[file:WPCSlamTilt.jpg|200px|thumb|left|A WPC game (STTNG) that has been "slam tilted".]] 
WPC games incorporate a slam tilt switch on the back side of the coin door. When closed, the game immediately stops, and the display fills with diagonal lines, as pictured at left. Note that this is not a power problem like a "game reset", below.
 

===Stuck Menu Settings (WPC-95)===
* Clear all the audits and reset to factory defaults.
* If using a battery for the RAM, remove/disconnect the batteries for a few minutes. Power up and check the settings to verify whether or not settings have become unstuck, then power off and reconnect the batteries.

====Stuck Language Setting (WPC-95)====
[[file:WPC95CountryCodeJumperTable.jpg|400px|thumb|right|DIP Switch language setting chart]]
If the MPU language can't be changed via the settings menu, it is possible that the DIP switch bank has failed.
* Be sure that the DIP switch language switches are set correctly as detailed in the table at right.
* Ensure that a DIP switch hasn't failed by buzzing for continuity across a closed switch.
* Use test T.15, "Dip Switch Test", to ensure that the MPU is reading the switches correctly. If the physical DIP switch settings do not match the T.15 test indications, then either the DIP switch has failed, or U11, a 74LS240, has failed.
[[file:Wpc95-dip-switch-test.jpg|400px|thumb|right|Test T.15, "DIP Switch Test"]] 

If there is a bad flipper opto board, this may also cause the language to get stuck (possibly in Spanish) and prevent the language from being changed in the menu settings or by using the MPU's DIP switches. Be sure to replace/repair the bad flipper opto board, then the language should then be able to be changed ([https://pinside.com/pinball/forum/topic/wpc-95-stuck-on-spanish-language-setting Discussion on Pinside])

=== Power Problems with the RottenDog aftermarket power/driver board ===
====Fuse Clips====
[[file:RottenDogFuseClips.jpg|300px|thumb|left|Fuse clips on a RottenDog WPC power/driver board.]] 
The fuse clips used on the popular RottenDog aftermarket power/driver boards are a bit brittle and do not snap back into position if too much bending force is applied to them, much like Data East power supply fuse clips. Once the fuse clip has been bent too much, it will not snap back into position to create a solid mechanical connection to the fuse. This can cause one of the various power voltages to be missing or intermittent.
 

====5V Regulator====
[[file:RottenDog5VRegulator.jpg|300px|thumb|left|The PTR08060WVD, used on RottenDog WPC Power/Driver Boards.]] 
Since the LM323K 5V regulator has been obsolete for many years, RottenDog Power/Driver boards were designed to use a DC-to-DC converter manufactured by Texas Instruments, part number PTR08060WVD. The part can be found [https://www.mouser.com/ProductDetail/595-PTR08060WVD here] and possibly at other vendors.

Note: This part is installed on a RottenDog Power/Driver board with the inductor (copper coil) facing the top of the board. Equivalently, pin 1 of the device should be installed into the left-most PCB through-hole.
 

===Game resets===
One of the more annoying faults exhibited by WPC machines is the chronic reset problem. The game will restart, often when both flippers are used at the same time. Note that game resets are a power issue. "Slam Tilts" are something completely different (see above).

There are several possible reasons for game resets. Before doing '''''any''''' work on the circuit boards, it is recommended that a number of much easier to fix, and just as probable root causes, be examined.

Possible causes are listed below, in the recommended order of examination. This order is a derived from a combination of "ease of examination" crossed with "probability of root cause". The standard advice dispensed on RGP to change BR2 and C5 is often wrong and unnecessary. If BR2/C5 are changed out and the game no longer resets, some will conclude that, sure enough, BR2/C5 was the problem. What is being missed is that along with replacing those components, at the very least, the connectors on the board are being reseated, the solder on the cap and bridge is being reflowed, and the board ground to the backplane is perhaps better due to torquing the screws better. Any of these changes can improve voltage/current enough to reduce the frequency or eliminate resets.

==== The "Replace BR2 and C5 Mantra" ====
And now, a word on the classic "BR2/C5 mantra".
[[File:NutAFingaS.jpg ‎|left|200px]]A long time ago…in a pinball galaxy far, far away…a kindly fellow was playing a nice game of pinball, hitting all the shots, and earning multiball after multiball. Just as he was about to beat the game’s high score to date, the WPC game MPU reset. "Not-A-Finga" he yelled in some ancient, dead, language.

A visitor from the neighboring planetary system noted that, "I once fixed that by replacing BR2 and C5". And lo, the mantra was born.

Fortunately, through advances in both our knowledge of these game systems, and the application of clearer thinking, we’ve come to realize that leaping to the “solution” of replacing components before doing real testing is not advisable. Most pinball owners do not possess the skill, experience, and tools that would allow them to work on circuit boards without damaging an expensive, and sometimes irreplaceable board. 

Still, with regular frequency, a post will be read on RGP or PinSide that goes something like this…"My game was resetting so I replaced BR2 and C5 and the resets vanished." This logical construct is known as [https://www.logicalfallacies.info/presumption/post-hoc/ "Post hoc, ergo propter hoc"] (after this, therefore because of this), an insidious logical fallacy that states "Since that event followed this one, then that event must have been caused by this one". Clearly, this is an invalid assumption. The fallacy lies in coming to a conclusion based solely on the order of events, rather than taking into account other factors that might rule out the connection.

In reality of course, when components are removed and replaced on a circuit board, the attendant "changes" to the state of the game system include…

# reseating connectors and possibly improving electrical conductivity
# possibly changing the connectivity through fractured solder joints which may be flexed differently
# reseating the entire board in the backbox and possibly improving ground for the board
# reflowing solder joints on both components possibly improving electrical conductivity
# possibly improving heat dissipation from the bridge to the heat sink by replacing thermal grease
# perhaps an air conditioner, refrigerator, or heater has shut off thereby increasing available electrical current

So please, hold off on heating up the soldering iron until methodically working through the disciplined process in the following section.

==== WPC 5VDC Power Derivation Path ====
Following is the nominal path from the wall plug to eventual consumers of the clean 5VDC power supplied by the Power/Driver board.
[[file:WPCPowerSelectButterfly.jpg|300px|thumb|right|WPC Transformer Power Configuration Plug, configured for US 120V systems.]] 

#120VAC/60Hz power is nominally provided at the wall plug. Different voltages are accommodated also (see below)
#An RFI (radio frequency interference) filter, which is seldom a contributor to game problems.
#Line power is connected to a service outlet sometimes incorporated into the metal "power box" and made available to the tech via a short, uniquely plugged, extension cord. Line power is wired in parallel and does not require the power switch to be in the ON position.
#Both sides of the AC power pass through the double pole/double throw (DPDT) game power switch
#The "black" side of the AC power passes through an 8A FB fuse housed in a bayonet style (screw in) fuse enclosure.
#The "black" side of the AC power then passes through the thermistor, which limits current inrush into the system.
#"Butterfly" voltage select connector used to accommodate typical voltage systems used around the world (120VAC in US, 230VAC abroad, low line voltage, etc). When configured for 120VAC in the US, the connector and wiring resemble a butterfly.
#Transformer Primary windings
#Transformer Secondary windings
#Yet another Molex connector, mating with the harness that will eventually lead to the Power/Driver board.
#Some games incorporate a "coin door interlock switch" which interrupts coil and flasher power when the coin door is open. If the game is equipped with this switch, there will be an extra Molex connector necessary to implement this switch.
#J101 on the Power/Driver board (WPC-95: J129)
#Full Wave AC rectification and smoothing via BR2 and C5 (WPC-95: D7 through D10 and C9)
#Regulation to 5VDC via the LM323K at Q1 (WPC-95: LM317 at Q1))
#Lighting LED4... (WPC-95: LED101)
#And finally, delivery to 5VDC power consumers via J114, J116, J117, and J118 (WPC-95: J101, J138, J140, and J141)

[[file:WPC95LM317VoltageAdjustResistors.jpg|300px|thumb|left|WPC-95 Voltage Adjust resistors R1 and R1]] 
Note that the LM317 is an adjustable voltage regulator where the LM323K is a 5V specific regulator. The LM317 is "programmed" to 5.108V using precision resistors R1 (750 ohms) and R2 (243 ohms), located just to the right of the LM317 heat sink. It is possible, although not advised, to adjust the output of the LM317 regulator to something other than the nominal 5.108 volts.
 

==== Possibly Skip Steps ====
If the game is resetting only within the first minute or two, and plays fine after that, skip to [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Failed_Thermistor Step 8, Failed Thermistor]. If the thermistor turns out to not be the cause, return to step 1.

==== The "Quick" but Temporary "Fix" ====
[[file:WPCJ101InSitu.jpg|300px|thumb|left|Connector J101 In-Situ (bottom of picture)]]
A quick but temporary fix might be to reseat (remove and then reinstall) J101 and J114 on the Power/Driver board and J210 on the MPU board several times. This might help in two ways.

First, the tarnish that builds up on the male/female connections might be removed slightly. This might be enough to return your game to service quickly. But this is not a long term repair. The proper repair is to repin both the male and female sides of the connectors.

Second, the physical point where the male/female pins meet becomes "welded" over time. That is, the pins develop micro-divots or irregularities that detract from a perfect connection. Reseating the connection may smooth out the defects that have formed and also might move the physical point of contact to a different part of the pins.

Again, reseating these connectors is a temporary fix that might work for a day, a week, or a month.

[[File:YT.png]] A Youtube video of this procedure being performed on a Bram Stoker's Dracula can be found [https://www.youtube.com/watch?v=8Pf7gRSlKo4 here].
 

==== Low Line Voltage ====
''Step 1: measure line voltage''
[[file:TestingLinePower.jpg|300px|thumb|right|Measure line power at the wall plug that the game is plugged into (not on the bench, as shown here). Almost 118VAC...Nice...]]
Low line voltage can occur for several different reasons...

*Peak summer usage may cause a drop in line voltage (at the wall). Nominal voltage should be 115VAC minimum.
*Too many games or "power hungry" devices on the same circuit. This is common when numerous devices are plugged into a power strip.
*Game(s) plugged into an extension cord or power strip with too small of wire gauge. If the game is plugged into an extension cord, make sure that it carries all three conductors and is constructed of '''at least''' 16 gauge wire, or specified as 16/3. Using a beefier 14/3 extension cord is better, and advised if more than one game is plugged into the cord.

If the machine is resetting, open the coin door and measure the AC voltage at the auxiliary socket with the machine turned off, and then with the machine turned on. If the voltage at the auxiliary socket is over 105VAC, the problem is most likely inside the game. If the voltage is below 105VAC, there is a line voltage problem and the local electricity company's help will be needed to correct the problem. 

==== Poor Ground Connection for Power/Driver Board ====
''Step 2: Make sure the power/driver board is screwed down tightly''

[[file:PoorWPCDriverBoardConnection.jpg|300px|thumb|left|As my friends in Texas might say, "that dog won't hunt". All backbox boards must be securely screwed down.]] 
A poor ground connection from the power/driver board to the backbox ground plane can reduce 5VDC by as much as .3 volts. Ensure that the screws that hold the power/driver board down, secure it tightly. 

==== Cracked Power or Ground Header Pins and Cracked Solder Joints at the 5V Fuse ====
''Step 3: Examine the header pins at J101, J102, and J103 as well as at the LM323K regulator (WPC-95: J136 and J137)''

[[file:WPCGroundHeaders.jpg|300px|thumb|left|Cracked header pin solder joints at J103 in a Twilight Zone, causing game resets.]] 
Similar to step 2 above, cracked header pins where the power enters the board or at the ground connections on the board can cause game resets. In the picture at left, cracked header pins at J103 (ground) in a Twilight Zone caused game resets. Either reflow the solder, or better yet, replace the headers with new pins.
 

[[file:FracturedSolderJointLM323K.jpg|300px|thumb|left|Fractured solder joints at the LM323K 5V regulator (WPC-95: LM317), causing game resets.]] 
Another place to examine for fractured solder joints is on the solder side of the board, where the LM323K (WPC-95: LM317) 5VDC regulator is placed. This area is subjected to very high temperatures that sometimes causes the solder to crystallize. If the solder joint is in any way suspect, remove the old solder and reflow new solder on the joint. Ensure that a nice solder "meniscus" is created (a volcano shaped solder joint) versus a "doughnut" around the wire lead.
 

[[file:F113CrackedSolderJoint.jpg|300px|thumb|left|Fractured solder joints at fuse F113.]] 
Fuse F113 (WPC-95: F105) fuses the 5V power for the game. Fractured solder joints here may cause the DMM to read near 5V, yet the joint doesn't allow enough current to pass. This can cause game resets and even cause the game to not boot. Reflowing the solder at these joints is prudent.
 

==== Missing diodes, open diodes, or cold solder joints at the Flipper coils ====
''Step 4: Examine flipper coil diodes''

[[File:ParallelCoilWindings.jpg|300px|thumb|left|Example flipper coil diodes shown on a FL-15411 flipper coil.]]
 
WPC flippers are, in general, the only coils in the game that should have diodes across the coil lugs. While diodes seldom fail, sometimes the pounding environment that flipper diodes must live within causes solder joints to fail. Ensure that each flipper coil has the required two diodes, that the diodes are good, and that they are soldered to the coil lugs with a quality solder joint. 

==== Poor Connections between the Transformer Secondary and the Power/Driver Board ====

''Step 5: Examine the "cube shaped" molex connector in the cabinet''

[[file:WPCTransformerSecondaryConnection.jpg|300px|thumb|left|The 15-pin Molex "cube" connector. The red wires carrying 9VAC to the Power/Driver board can be seen here.]] 
The connections from the transformer secondary to the Power/Driver board can degrade over time, a natural result of hours and hours of "power on" time. Try re-seating each connector. If the reset frequency is reduced or disappears, then the root cause has probably discovered. These connectors should be repinned at a minimum with at least new pins (the connector housings may be salvageable) for a long term solution. It is especially important to re-pin the red 9VAC wires that carry power to the Power/Driver board as this is converted to the 5VDC logic voltage.

Note: the molex pin extractor for these "round" pins is relatively expensive but there is no other good way to remove the pins.
 

==== Poor Connection at J101 on the Power/Driver Board ====
"Step 5.5: Examine both male and female connectors at J101 (WPC-95: J129)"

[[file:WPCJ101InSitu.jpg|300px|thumb|left|Connector J101 In-Situ (bottom of picture)]] 
J101 (WPC-95: J129) connects the transformer secondary supply of both 9VAC (solid colored red wires, ultimately used to create 5VDC power) and 13VAC to the power/driver board. This connector often becomes tarnished, increasing resistance and reducing the effectiveness of the circuit. Reseating the connector may temporarily reduce reset frequency. This is an indication that this connector should be repinned. As always, it's best to repin both the male and female connectors.
 

==== Poor Connections between the Power/Driver board, the CPU, and other PCBs ====
''Step 6: Examine other wiring harnesses and the connectors''

[[file:WPCPickingUpGround.jpg|300px|thumb|left|A convenient location to find ground in a WPC backbox.]]
[[file:WPCTesting5VDCatTP2.jpg|300px|thumb|left|Measuring DC voltage at the 5VDC test point, TP2.]] 
Measure DC voltage at TP2 (WPC-95: TP101) on the Power/Driver board.
#DMM set to DC volts (if not an auto-ranging meter, expect to measure 5VDC)
#Black lead secured to game ground (the ground braid in the head is a good place to pick up ground)
#Red lead on TP2 (WPC-95: TP101). Remember the reading.
 

[[file:WPCTesting5VDCatGameROMPin32.jpg|300px|thumb|left|Measuring DC voltage at pin 32 of the game ROM]] 
Measure DC voltage at the CPU board.
#Again, DMM set to DC volts
#Black lead in the same place
#Red lead on pin 32 of the game ROM, or on pin 2 (center pin) of the MC34064 under voltage watchdog at U10
#Record this reading

Compare the two readings. ANY difference indicates voltage loss between J114 on the power/driver board and J210 on the MPU board. Some voltage loss is expected/natural since no circuit path can provide zero resistance. A difference of .1VDC is enough to warrant examination of the connectors between J114 (WPC-95: J105) on the Power/Driver board and J210 on the CPU board.

Reseating the wire harness that connects the power-driver board to the CPU board may identify the root cause (but reseating is not a long term solution).
 

[[file:WPCZConnector.jpg|300px|thumb|left|The "Z" connector, as used in Twilight Zone, etc.]]
[[file:WPCZConnectorHarness.jpg|300px|thumb|right|The entire harness containing the "Z" connector in Twilight Zone can be removed from the game for easier repinning.]] 
Some games use an interceptor harness to power extra boards (IJ, TZ, WH20, STTNG, FT, etc). There is a inline splice connector (commonly called a Z-connector) between the driver board and the CPU board. The Z-connector can become loose and/or oxidized, contributing to a poor electrical connection between the female connectors. The Z-connector can be replaced with a new one, or more robustly, eliminated by splicing the wires together, soldering, and heat-shrinking. This entirely removes the Z-connector as a contributing factor to game resets.

At least on Twilight Zone, the wire harness that contains the "Z" connector can be removed from the game entirely, as shown at right. This harness has been repinned and the "Z" connector eliminated.
 

[[file:PoorIDCConnections.jpg|300px|thumb|left|A poorly "repunched" IDC connector. This connection was probably "punched" with a small flat-blade screwdriver. Note the bare wires where the insulation has been damaged. Yikes!]] 
Some field techs will "repunch" IDC connectors in an attempt to make a better connection. Without the correct punch tool, sometimes an even worse connection is created, as pictured at left. If the decision is to use IDC connectors, at least use the correct tool to punch the wires.
 

[[file:WPCWornPowerConnectionJ210.jpg|300px|thumb|left|MPU connector J210. This connector has had the plating worn off right where the female connector mates with it. When mated with a worn female connector, increased resistance results in reduced voltage, causing resets and possibly failure to boot.]] 
Tarnished, heat damaged, or damage to header pin plating creates resistance and can sometimes be a contributor to game resets. If the male header pins are tarnished, their female mates are probably tarnished also. If tarnished pins are found, now might be a good time to remove that aspect as a contributor to game resets.
 

If following this step-by-step process, now is the first time that a soldering/desoldering station will be needed.

Replace the male header pins, remembering to clip the correct "key" pin before reinstalling the board into the game.

Replace the female connector and pins with good quality Trifurcon crimp-on pins. IDC (Insulation Displacement Connectors) connectors as found originally on the game were used by the OEM to speed the manufacturing process and do not provide the level of robustness that can be achieved using Trifurcon crimp-on pins and good technique.

Another possible contributor to poor power connections is cracked header pin solder joints. Although, with WPC double-sided PCBs and the relatively large header pin through-holes, this is rarely seen. Should you identify cracked header pin solder joints, it's best to remove as much of the old solder as possible before reflowing new solder at the joint.

Be sure to check the power connections on the display as well. One documented repair involved a Funhouse with a reset issue. The game had a strong +5V signal on the MPU/CPU, a new BR2/C5 and digital voltage regulator. It would play perfectly until someone nudged the machine causing it to reset. During troubleshooting, it was noted that the game would reset (even in attract mode) when the display was lifted out of the backbox or placed back in it. It was then observed that the 2 wire/3 pin power connector had a loose IDC connection. The ground short through vibration was resetting the CPU! Repinning both the male and female ends of this connector with a proper molex housing resolved the issue.
 

==== Using a Multimeter to Test the Bridge Rectifier and Capacitors ====
''Step 7: Bridges and Caps in circuit''

[[file:WPCTestingBR2RectifiedDCVoltage.jpg|300px|thumb|left|Measuring "un-smoothed" DC voltage output from BR2. The voltage is smoothed later by C5. This bridge is functioning properly.]] 
There's one last test we can do before disassembling parts of the machine. This test can clearly identify a bad bridge rectifier or capacitor. You will need a clip lead.

#With the machine off, clip the lead onto the top left lead (positive) of BR2. You will have to do this by feel, as you cannot see the lead. This clip point is the output of the bridge rectifier, and is connected to the smoothing (filter) capacitor and LM323K regulator input. It should be at 9V DC.
#Next, place the other clip on the red (+) lead of your meter.
#Connect the black lead to ground by tucking it under the braid. Check your installation to make sure that nothing is shorting.
#Set your meter to DC volts.
#Turn on the game.

The meter should read about 9V. This will be true whether C4/C5 are working or not. If the bridge rectifier is bad, it will read about 7V.

For the capacitor, turn your meter to AC volts. Note that inexpensive meters may give false readings here. Ideally, your meter should be a true RMS meter. Good capacitors will read about 300mV AC. Bad capacitors will read up to 2VAC. Anything over 1VAC indicates a failed/failing filter capacitor at C5 which should be replaced.
 

==== Failed Thermistor ====
''Step 8: Examine the Thermistor''

[[file:WPCPowerBoxInside.jpg|300px|thumb|left|A look inside a typical WPC power box. This particular box was from a Fish Tales. The Thermistor is grey, the varistor is green.]] 
The thermistor is (generally) a black or grey disk, about the size of a dime. It is located inside the power box which is found just inside the coin door and to the right. If your game has one (and not all WPC games do), it will be connected in series between the power box fuse and the black side of AC power. Note that the power box may also contain a "varistor", or MOV, which is essentially a surge protector. The varistor will be wired in parallel with (across) the AC power. The varistor is not a factor in game resets.

The thermistor's job is to limit current inrush into the capacitors when the game is first powered on. This reduces stress on the bridge rectifiers or diodes in the game's power circuits (which is the primary cause of bridge rectifier failures). After a few seconds, the thermistor heats up and drops to a very low resistance. Failing thermistors pass less current and have to get hotter to work. This heating takes time, so the game will often reset in the first 30 minutes of operation, and then be fine afterwards. Obviously, a cold environment will make the symptoms worse, and a warm room may appear to cure the problem. 

Resetting while the game warms up is therefore a key indicator of a failing thermistor. Note also that DCS and WPC-95 A/V boards may reset independent of the MPU. If this is the case, you'll hear the characteristic same "bong" as when the game boots. 

'''***Safety Warning***''' Unplug the game '''AND''' turn the game off before conducting the following test.

Sometimes, the thermistor may be visibly damaged. However, it may look good and still be bad. An easy test of the thermistor is to jumper across the legs of the thermistor with a heavy gauge wire. If the game resets no longer occur, replace the thermistor with the correctly rated part. The original Williams part number is 5016-12978-00. A replacement is available from [http://www.greatplainselectronics.com/search.asp?pg=1&stext=5016-12978-00 Great Plains Electronics].

While you have the box open try wiggling the connectors (the game '''''IS''''' unplugged!) you probably will find at least one that is loose - this can contribute to reset issues. The fix is to solder all the crimp quick connect ([http://www.pinwiki.com/wiki/index.php?title=File:DSCF0810.JPG examples on coil]) wires to the pins they were connected to in the box: cut the quick connects off, one at a time, and then solder the wires directly. Insulate the connections with Heat-Shrink or a good grade of electrical tape.

==== Questionable Prior Rework ====
''Step 9: Examine prior rework''

The printed circuit boards used in pinball machines sometimes have traces on both sides of the board. Most WPC boards are manufactured in this way. The traces are joined through the board by a thin layer of copper, plated to the inside of the hole. This plating is delicate. Without great care, the plating can pull out or crack when components are removed, especially alkaline damaged components as found on MPU boards (after batteries have leaked) and "snap caps" as found on OEM WPC Power/Driver boards (at C5 for instance).

Extreme care as well as good technique must be exercised when removing these components as it is very easy to lift traces or damage through-holes on the board. If the component is known to be bad, it is sometimes easier to snip the component from the board with a flush cutter and remove each leg of the component individually.

An excellent way to repair a lifted trace or cracked through-hole is to create a [http://www.pinwiki.com/wiki/index.php?title=General#Repairing_traces_or_creating_a_.22solder_stitch.22 solder stitch] between the traces on each side of a two sided board. Some PCB repairmen will install jumpers as a "repair" for cracked through-holes or to "guarantee" connectivity between components. Some PCB repairmen will avoid the use of jumpers in favor of better looking rework.

==== Failed Capacitors ====
''Step 10: Power smoothing capacitors at end of life''

[[file:WPC-C4InSitu.jpg|300px|thumb|left|C4, shown "in-situ" on a typical WPC Power/Driver Board. A new C4 cap has been installed on this board (100µF/10V). Nice job by the installer orienting the cap so that its value is in easy view!]] 
Electrolytic capacitors do not last forever. They are designed to operate for about 1,000 hours at their full rating. Capacitor life is a function of temperature: the cooler the capacitor operates, the longer the life. The system designer must select higher voltage and capacitance ratings to achieve the design life, which can be as short as 5 years in a pinball machine operated continuously in a warm environment.

The WPC Power/Driver board uses a 15,000µF, 25V capacitor at C5 to smooth the full wave rectified AC from BR2. When this capacitor is no longer smoothing the rectified AC well enough to produce a clean 5VDC, the voltage may drop below the threshold enforced by the watchdog circuit on the MPU (an MC34064 at U10). When this happens, resets sometimes result.

Note that commonly available replacement capacitors are rated to 35V, and will work fine for this application. In general, you may use a capacitor rated for higher operating voltages but the capacitance specification (µF, or micro-farads) should not be changed.

C4 (spec'd at 100µF, 10V, axial) can sometimes fail and cause the game to reset also. If you've gotten this far and are replacing C5, you might as well replace C4 too.
 

[[file:PulledThroughHole.jpg|300px|thumb|left|A good view of a 15,000uf cap, with a pulled through hole still on the left lead (the brown donut looking object)]]
[[file:DomedFilterCap.jpg|300px|thumb|right|C5 (lower) and C11 (upper) on a WPC-089 power/driver board. C11 is clearly "domed", a physical indication of it's failure.]] 
Removing the big 15,000uf capacitors on a WPC-089 power/driver board is a bit tricky. More often than not, an amateur will damage the through hole that connects one side of the board to the other, either severing the connection completely, or badly enough to cause intermittent reset issues. Should the through hole be pulled, a [http://www.pinwiki.com/wiki/index.php?title=General#Repairing_traces_or_creating_a_.22solder_stitch.22 solder stitch] needs to be installed, or "jumpers" need to be installed connecting the associated bridge rectifier to the capacitor.

Advice: Without the experience, tools, and technique to accomplish this task, most hobbyists would be well advised to send the board to a pro for rehab.

[[File:YT.png]] A video demonstrating an excellent technique for removing snap caps can be found [https://youtu.be/rs90-UMtCww here].
 

==== Failed Bridge Rectifier ====
''Step 11: Test Bridge Rectifier #2 (BR2)''

The thermistor protects the bridge rectifiers from inrush current. Still, bridge rectifiers will occasionally fail.

''Testing a bridge rectifier is simple.''

[[File:TestingABridgeRectifierFourSteps.jpg|300px|thumb|left|Four Connections to Test a Bridge Rectifier. Black/Red dots represent test lead positions.]] 
The picture at left illustrates the 4 readings to be taken when testing a bridge rectifier.

'''Procedure:'''

#Place your DMM into "diode test".
#Put the black lead of your DMM on the "oddball" lead of the bridge rectifier. This will be the lead that isn't oriented the same as the others (as with the "spade" type of bridge) or the lead that prevents the four legs from forming a square (as with the "wire lead" type of bridge). This will also be the DC positive lead of the bridge.
#Place the red lead of the DMM on each of the adjacent legs, one at a time.
#A reading nominally between .5 and .7 should be seen (this represents the voltage drop across the bridge's internal diodes).
#Swap locations of the red and black leads. A reading of "null" should be seen.
#Now place the red lead of the DMM on the lead opposite of the "oddball" lead, or the DC negative lead of the bridge
#Place the black lead of the DMM on each of the adjacent legs, one at a time.
#Again, a nominal reading between .5 and .7 should be seen.
#Swap locations of the red and black leads. A reading of "null" should be seen.
 

[[File:TestingBridgeRectifier.jpg|300px|thumb|left|Testing a Bridge Rectifier in circuit. This part of the bridge is good.]] 
Readings outside of these ranges indicate a failed or failing bridge. Note that these readings are not "hard and fast". For instance, a reading of .462 is probably acceptable. We are looking for an "open" or a "short". Note also that this test is not conducted "under load" and it is possible for the bridge to test "good" when it will in fact fail under load (this is also true when testing diodes, transistors, etc).
 

[[File:WPC Brdg 1and2 Removed2.JPG|300px|thumb|left|Applying heat transfer grease (heat sink compound) to the new bridge rectifiers.]]
[[File:WPC Brdg 1and2 Removed3.JPG|300px|thumb|right|New bridge rectifiers screwed to heat sink before placing on driver board.]] 
Should you decide to replace the bridge, it is best to screw the heat sink to the bridge before soldering it in place as the heat sink is shared between BR1 and BR2. A small amount of heat sink compound between the bridge and the heat sink is necessary. This compound improves conduction of the heat away from the bridge and into the sink. 

Some repair tips suggested cutting the heat sink in half, separating it into two parts, one part for each bridge. This technique is no longer considered to be a best practice.

Solder both the top and bottom solder pads of the bridge. Should the through-hole of the bridge leads be cracked or otherwise damaged, use the "[http://www.pinwiki.com/wiki/index.php?title=General#Repairing_traces_or_creating_a_.22solder_stitch.22 solder stitch]" technique noted above or install jumper wires between the DC outputs of the bridge and the terminals of C5. When clipping the leads of the wire bridge, do not cut into the solder "meniscus" (the "volcano" of solder around the wire lead). Cutting into the solder meniscus can cause cracked solder joints later. 

[[File:WPC Brdg 1and2 Removed.JPG|300px|thumb|left|Bridge rectifiers 1 and 2 removed elegantly with a desoldering iron.]]
[[File:WPC Brdg 1and2 Reinstalled.JPG|300px|thumb|right|New bridge rectifiers installed, and replacement date noted.]] 
With proper desoldering tools, like the Hakko 808 or Hakko 470D, removal of bridge rectifiers and other components is greatly simplified. After replacement of bridge rectifiers is made, it's not a bad idea to mark the replacement date. In doing this, you or anyone else will know when these were replaced, and more importantly that they were replaced. 

==== Failed Voltage Regulator ====
''Step 11: When all else fails...''

The LM323K 5V regulator is a robust device, but it can drift over time to below the design requirement of 4.8VDC. If your 5VDC reads less than 4.8VDC at the test point, or less than 4.75V on the CPU board, you have to replace the regulator. Note that these voltages are compliant to the LM323K's spec. However, at the lower end of this spec, this lower voltage may be the cause of resets.

[[File:EZ-SBC-PS5.jpg|300px|thumb|left|The EZ-SBC PSU5 modern adjustable switching voltage regulator]]
If you decide to replace the LM323K regulator you may wish to consider using an [http://www.ezsbc.com EZ-SBC PSU5] instead. The PSU5 is a 5V 3A high-efficiency switch-mode regulator that is a direct replacement for the LM323K in terms of form factor and current capacity; it is superior to the LM323K due to its reduced power dissipation. When using the PSU5 be sure to replace the KEPS nuts (nuts with captive lock washers) originally used to mount the LM323K with discrete #6 split lock washers and #6-32 hex nuts; the external tooth lock washer of the KEPS nut can contact one of the surface-mounted components on the PSU5.

Note: The EZ-SBC PSU5 has one side affect that may be annoying. At power off, instead of the customary "pop", the speakers emit a loud volume "machine gun" or "fart" sound. While this might be unnerving, it is perfectly harmless. An updated version of the PSU5, identified by a yellow solder mask, does not have this side effect at power off. It is otherwise identical to the original PSU5. 
[[File:YT.png]] An example of the sound can be heard [https://youtu.be/L4MDGddZanI?t=80 here] near the end of the video.
 

==== Failed Electrolytic Capacitor on the MPU ====
''Step 12: Failed C31 on the MPU''

[[File:FailedC31onWPCMPU.jpg|300px|thumb|left|C31 on the MPU. This Philips capacitor has most likely failed.]]
There is one more possibility. C31 acts as a filter on the WPC-089 MPU. It is a 100µF, 10V capacitor, connected between incoming 5VDC and ground. Williams used two primary suppliers for this capacitor, Philips and Illinois Capacitor. If the capacitor is grey with black markings and has the logo "iC" on it, then it is from Illinois Capacitor and is likely ok. However, if the capacitor is blue and shows the manufacturer as Philips, you should replace it as it is most likely bad. The small Philips capacitors in particular have shown an increasing failure rate as these machines get older. This does not only apply to their use on the CPU but anywhere else in the machine. Which means the same rule applies to C4 on the power driver board - if it's a Philips capacitor replace it. If it's an iC capacitor it is likely OK. If you have a spare CPU, swapping the suspect one with a known working CPU is a good diagnostic step.

When replacing this capacitor it is best to use a 100uf 25v capacitor. You should note that by the time Williams got to the WPC-95 system, any place where they used to use a 100uf 10v filter capacitor they now had a 100uf 25v capacitor instead.
 

[[Image:BSDcaprs.jpg|300px|thumb|left|Failed C31 from a BSD CPU.]]
[[Image:FHcaprs.jpg|300px|thumb|right|Failed C31 from a Funhouse CPU.]]
Determining whether or not C31 has failed is a challenge without an ESR meter. A simple visual inspection will not indicate whether the part is good or bad. Here are two C31s, one from a Funhouse and one from a BSD. Both of these are bad. Both should have an ESR reading of less than 2 ohms and a capacitance reading, out of circuit, of 100uf if not slightly more. Both the boards these were installed in would boot successfully on the bench hooked up to a dedicated power supply. Without an ESR meter, one might think these capacitors were fine. In fact, if this was the only thing wrong in the machine on the 5v circuit, chances are the game would operate fine with these capacitors as-is. But if the game is resetting, it is probably best to replace C31.
 

==== The Absolute Last Resort ====
''Step 42: We really didn't want to get to this point!''

'''There is a method of absolute last resort.''' 

The LM323K is an adjustable linear regulator. However, Williams provided no means to adjust the output of the LM323K. As such, the LM323K will deliver a voltage anywhere within the spec range of the device. The spec output voltage range for the LM323K is 4.75 to 5.25 VDC. Some percentage of LM323Ks will fall into the lower range of that spec, which is at, or just above the trip point voltage of the MC34064 voltage watchdog on the MPU board.

The following procedure will increase the output voltage of the LM323K slightly. This procedure is not a substitute for addressing all of the considerations mentioned in previous steps, and should be used cautiously.

[[File:LM323KHackComponentSide.jpg|thumb|300px|right|Ground Trace severed leading to C9.]]
The LM323K draws a small current to operate, which it passes to ground. We can use that current to raise the voltage of the whole LM323K, pushing the output closer to 5V. 
'''Procedure:'''
#Isolate the LM323K's metal case from board ground by cutting the ground traces that run left and right from the nut on the back of the board that bolts the LM323K to the board. The neater you make these cuts, the easier it to reverse this hack.
#Some versions of the Power/Driver board include a ground trace on the component side of the board that provides a ground to the tantalum capacitor at C9. This trace must be cut on the component side of the board.
#Add a 1/2W resistor in series, from the LM323K ground to the board's ground trace.
 

[[File:LM323KHackSolderSide.jpg|thumb|300px|left|LM323K case isolated from ground, and a 25ohm resistor added. This raised the nominal voltage by .2VDC.]] 
A 12 ohm resistor will nominally raise the LM323K voltage output by .1 VDC. 
A 24 ohm resistor will nominally raise the LM323K voltage output by .2 VDC. 
 

==== The Conductive Grease Hack ====
[[What is a "Hack"?]]
Some techs will recommend the use of conductive grease to improve conductivity at a connector. While some techs will "swear '''by''' the stuff", other techs will "swear '''at''' the stuff", and as such, this is not considered a best practice. The grease can extend the life of new header pins, and protect against hostile environments that would cause corrosion. However, when used on header pins that are already damaged, grease can only slow further deterioration. Worse, the heat in the connector will turn the grease to gunk. If you find a flaky connector with gunk in it, you've been "greased" and you will want to re-pin it.

Damaged/burnt connectors should always be [http://www.pinwiki.com/wiki/index.php?title=General#Electrical_Tools replaced]. [http://http://www.dowcorning.com/applications/search/products/details.aspx?prod=01903128&type=prod Dow Corning #4] grease can't help them.

On the other hand [http://http://www.dowcorning.com/applications/search/products/details.aspx?prod=01903128&type=prod DC#4] Electrical Insulating Compound Grease does a superior job reducing friction and corrosion on contacts and that would be considered a net benefit to any game. JRR's shop and others have also found a decrease in the temperature of power contacts using [http://http://www.dowcorning.com/applications/search/products/details.aspx?prod=01903128&type=prod DC#4] along with reduced resistance which should increase the life of the connector. This product is also good to use on EM pins for the interconnect plugs/sockets as it reduces friction and improves conductivity.

Note that [http://http://www.dowcorning.com/applications/search/products/details.aspx?prod=01903128&type=prod DC#4] is stable from -57C to 204C (-70F to 399F). If your game has contacts at the high end of those temperatures then certainly, the [http://en.wikipedia.org/wiki/Magic_smoke smoke] would be getting out...

If other products are used, investigate carefully to ensure they are a proper dielectric grease suitable for high temperature applications. There is a time and place to use this type of product, mostly as a preventative measure on newly replaced contact surfaces. Applying it after the plating has burned off is a questionable practice and no substitute for proper connector replacement.

===Check fuses F114 and F115 message===
[[File:CheckFusesF114andF115.jpg|thumb|300px|left|Check Fuses F114 and F115 Message]]
This message is sometimes displayed when the game boots and a game cannot be started. Most of the time, F114/F115 will be found to be just fine.

The game issues this message because it cannot read the switch matrix normally. The crafty designers at Williams inserted an “always closed“ switch into the matrix as switch 24. Switch 24 isn’t a switch at all, but instead provides the game software with a “known closed” switch matrix return. Switch 24 is actually a diode across column 2, row 4 of the switch matrix and is located on the coin door interface board.

Since the WPC switch matrix circuitry on the MPU uses 12V to determine switch state, the game assumes that the 12VDC power has been interrupted. F114/F115 fuse the 12V generation circuit; F114 on the AC side of BR1; F115 on the DC side of BR1. Hence, the game assumes that one of these fuses is blown and the message is displayed.
 
'''Diagnosing the problem'''

Start by checking DC voltage at TP3. You should see about 12VDC. If not, follow these steps.

#Actually check fuses F114 and F115 using the procedure [[General#Testing_fuses| here]]. If a blown fuse is found, replace it. If F114 immediately blows again, then BR1 is probably shorted. Skip to the paragraph below to test the bridge.
#Check LED6. If not lit (indicating the absence of 18V at TP8), then suspect BR1 or the filter caps for BR1, C6 and C7. If BR1 had failed shorted or if C6 or C7 where shorted (rare) then you would expect to see F114 blown. BR1 can be tested using the procedure below.
#Check LED1. If not lit (indicating the absence of “digital” 12V at TP3, then test D1 and D2 (both 1N4004 diodes that can be tested with the game off or board removed using the standard "diode check" on your DMM).
#If D1/D2 test good, then check continuity from pin 2 of the 7812 voltage regulator at Q2 to J114, pin 5. This verifies the path to ground.
#Next, check continuity from pin 3 of the 7812 to J114, pin 2. This verifies the path through F115 to the 12V power header at J114.
#If this all checks out, yet 12VDC is still not at TP3, then suspect the 7812 voltage regulator at Q2. Q2 is in a TO-220 package (like a TIP-102) and has a small heat sink attached.

'''Alternate Problem Determination Method: Test Power Across the Driver Board'''

[[File:WPC12VRegulatedCircuit.png|center|(The regulated 12VDC circuit, diagram by by Sascha Voksuil aka Zaza)]] 
The diagram above shows the simple path for the 12VDC power regulation circuit. Power may be tested across the circuit, as follows.
#Turn the game on.
#Set your meter to DC volts. If your meter isn't an auto-ranging meter, expect to see less than 20VDC.
#Clip the black lead of your DMM to game ground, or tuck it under the backbox ground braid.
#Probe TP8 with the red lead of your DMM. It should measure about 18VDC. If not, suspect F114.
#Probe the banded side of D1. It should measure about 18 minus .5 to .7 volts, (the typical voltage drop across this kind of diode), or about 17.4VDC. If not, suspect D1.
#Probe the banded side of D2. It should measure about 17.4 minus .5 to .7 volts (again), or about 16.8VDC. If not, suspect D2.
#Probe the top leg of the 7812. It should measure about 16.8V. If not, suspect the trace between D2 and the 7812 or a fractured solder joint at the 7812.
#Probe the bottom leg of the 7812. It should measure about 12VDC since the job of this regulator is to produce 12VDC. If not, suspect the 7812 regulator.
#Probe the right side of fuse F115. It should measure about 12VDC. If not, suspect the trace between the lower leg of the 7812 and fuse F115. In particular, suspect that C2 has leaked and corroded the trace carrying the 12VDC. See: "Leaky Capacitor C2 corrodes trace", below.
#Probe the left side of fuse F115. Again it should measure about 12VDC. If not, suspect F115 is blown or the fuse block has a poor mechanical connection to the fuse or to the PCB.
#Finally, probe pin 2 of J114. It should read about 12VDC. If not, suspect the trace from fuse F115, the connection of the F115 fuse block to the PCB, or a fractured pin at J114.

The only circuit path remaining to test is the path to the ground pin of J114 (pins 5 and 7) from the 7812. This is easily accomplished with power off.

#Set your DMM to continuity and "buzz" between the tab of the 7812 to J114, pin 5 and 7. If no continuity, suspect a fractured solder joint at the center pin of the 7812, or corrosion under C2 that has compromised the trace.

'''Short on the MPU causing F115 to blow'''

There is one more way for the 12VDC power to be lost and for F115 to blow. A shorted IC on the MPU that uses 12VDC can cause F115 to blow. To help isolate the problem to the MPU, replace F115, disconnect power going to the MPU at J210, and turn power to the game on. If the fuse does not blow, the problem is almost definitely on the MPU board. Any of the LM339s (theoretically) or the ULN2803 (definitely) can fail and short 12V to ground, causing F115 to blow.

'''Leaky Capacitor C2 corrodes trace'''

[[File:WPCFailed12VRCircuit.jpg|thumb|300px|left|Filter capacitor C2 (removed), leaking it's corrosive electrolytic contents, eating through traces]]
[[File:WPC12VFilterCapLeakDamage.jpg|thumb|300px|right|Filter capacitor C2 (removed), showing damage caused by a leaky cap.]]
 
Yet one more way for the 12VDC regulated power to be lost is shown in the picture at left. In the picture, the electrolytic cap at C2 has failed and leaked corrosive electrolytic contents onto the board. The lower trace from Q2 (7812 voltage regulator) to C2 (+ side), that goes on to connect to F115 on the solder side of the board, has been eaten away, no longer providing a path for the regulated 12VDC power. Corrective action here is the same as alkaline damage abatement.

Shown on the right is another shot of the damage caused by a leaky cap at C2. This one resulted in reducing the 12V power to about half of spec. 

[[File:WPC12VCorrosion.jpg|thumb|300px|right|Corroded parts in the 12V/Zero Cross circuitry]]
The corrosion resulting from a leaky cap at C2 can be quite extensive. Often, the parts immediately left of C2 are damaged and must be replaced. The part list is as follows:
*R206 - 27K ohm
*R198 - 10K ohm
*R199 - 1K ohm
*C1     - .001uf ceramic (or 1000pf, marked 102)
*R204 - 270 ohm
*C12   - .001uf ceramic (or 1000pf, marked 102)
*R205 - 270 ohm 

If TP3 does, in fact, have 12VDC present, then we need to dig deeper.

#First check for 12VDC on the CPU board to ensure that the 12V is getting to the board via the 2 (and possibly 4 if your game has a “Z-Connector”) connectors that carry the 12VDC. An easy place to measure 12VDC on the CPU is at pin 10 of the ULN2803 (U20). Pin 10 is on the bottom row of pins, furthest left. Note that this connection (and also the 12VDC connection to pin 3 of the LM339s) is not shown on the schematic.
#If the CPU is receiving 12VDC, and you still have the “Check fuses F114 and F115” message, then the problem lies within the CPUs switch matrix logic circuitry.
#Prime candidates for CPU switch matrix failure are U20 (a ULN2803), the two LM339s at U18 and U19, the 74LS374 at U14, and the 74LS240 at U13. All of these ICs are in the “corrosion zone” caused by leaky alkaline batteries. If your CPU exhibits the “blue/green fuzzies”, address the alkaline damage first.
#Testing the 74LSXXX ICs is simple using the procedure [[General#Testing_an_integrated_circuit| here]].
#If coil power, flasher power, or even lamp power was somehow shorted to the switch matrix, there is a near 100% probability that the ULN2803 at U20 has been damaged. There is no good way to test the ULN2803 other than using a logic probe with the game powered on. Both the input side and the output side of the ULN2803 should be toggling between logic 0 and logic 1. If not, socket and replace the ULN2803.

[[File:TestingBridgeRectifier.jpg|300px|thumb|right|Testing a Bridge Rectifier in circuit]]
'''Testing a bridge rectifier is simple.'''
#Place your DMM into "diode test".
#Put the black lead of your DMM on the "oddball" lead of the bridge rectifier. This will be the lead that isn't oriented the same as the others (as with the "spade" type of bridge) or the lead that prevents the four legs from forming a square (as with the "wire lead" type of bridge). This will also be the DC positive lead of the bridge.
#Place the red lead of the DMM on each of the adjacent legs, one at a time.
#A reading nominally between .5 and .7 should be seen (this represents the voltage drop across the bridge's internal diodes).
#Now place the red lead of the DMM on the lead opposite of the "oddball" lead, or the DC negative lead of the bridge.
#Place the black lead of the DMM on each of the adjacent legs, one at a time.
#Again, a nominal reading between .5 and .7 should be seen.

Readings outside of these ranges indicate a failed or failing bridge. Note that these readings are not "hard and fast". For instance, a reading of .462 is probably acceptable. We are looking for an "open" or a "short". Note also that this test is not conducted "under load" and it is possible for the bridge to test "good" when it will in fact fail under load (this is also true when testing diodes, transistors, etc).
 

'''Testing BR1 "InSitu"'''

It is possible to test BR1 while the power/driver board is still installed in the game. Thanks to PinSider "Zaza" for the procedure and animation.
#Power the game off
#Ensure fuse F114 is good
#Remove connector J101 on the right side of the power/driver board
#Set your DMM to "diode check"
#Probe as indicated in the animated gif pictured below

[[File:TestingBR1InSitu.gif|Testing BR1 "InSitu".]] 

[[File:Wpc-br.jpg|300px|thumb|left|The heat sink covering BR1 and BR2 on a WPC-board]] 
Take special care when replacing a bridge rectifier. It is easy to lift the traces of the plated through holes when removing these. After removing the heat sink, cut the old bridge rectifier off of the board close to the top leaving as much of the lug as possible. Then add a small amount of solder to the connection on the solder side to improve heat transfer. Finally apply the iron to the solder side to heat the joint and remove the remaining lug with small pliers.

When replacing the new bridge rectifier you should remove the old thermal compound and apply a new thin layer. The old compound can be removed with a little rubbing alcohol. Apply the thermal compound to the top of the bridge rectifiers and reattach the heat sink with the screws [[#Failed_Bridge_Rectifier | (see above)]]. It is much easier to replace the heat sink before resoldering the new bridge rectifier. Make sure that the heatsink is sitting flush with the tops of the bridge rectifiers and that you leave about a 5/8" gap between the bridge rectifier and the board to improve air flow.

Splitting the heat sink between BR1 and BR2 was at one time thought to improve reliability. This is no longer considered a best practice and is not recommended. 

[[File:Wps-diodes.jpg|300px|thumb|left|Diodes replaced BR1 and BR2 on WPC-95 boards]] 
In WPC-95 games, BR1 and BR2 were replaced by a series of diodes. D11-D14 replaced BR1. D7-D10 replaced BR2. These are much less prone to failure. Still, they do fail on occasion. If one or more fail, it's best to replace all four in the "gang". These diodes were originally 6A2 diodes. Replace them with 6A4 diodes (6 amp 200V vs 6 amp 400V). See the "Check Fuses F106 and F101" section below for the equivalent WPC-95 message.
 

===Check Fuses F115 and F116 Message===
[[File:WPC Check F115 F116.JPG|thumb|300px|left|Check Fuses F115 and F116 Message]] 
Similar to the "Check Fuses F114 and F115" above, games like Demolition Man will display this message at power up if the trough optos are seen as closed (remember, the opto switch open/closed logic is inverted). Debug this issue by checking the 12v connectors at the lower left corner of the driver board and the connectors on the trough opto transmitter and receiver board.
 

===WPC-95 Check Fuses F106 and F101 Message===
[[File:CheckFuses106And101.jpg|thumb|300px|left|Check Fuses F106 and F101 Message]] 
If a WPC-95 game detects loss of 12VDC power by not seeing switch 24 as closed, "Check Fuses F106 and F101" will be displayed at power up. This could obviously mean that F101 and/or F106 are blown. It might also indicate failure of the LM7812 12VDC regulator at Q2 in which case LED102 will be on and LED100 will be off or, failure of one or more of the 6A2 diodes that rectify the AC power (D11-D14). In the latter case, both LED102 and LED100 will be off. Use these LED indicators, as well as testing for 18VDC at TP102 and 12VDC at TP100 to guide your repairs.
 

===Line Voltage Detection - LED2 & LED3===

LED2 and LED3 on the Power Driver Board are indicators for the line voltage detection circuit. On on-board comparator circuit uses +5V and +18V to check the line voltage. The comparator consists of a resistor voltage divider and an LM339 comparator.

The following table shows how to interpret the LED states. Note that other problems with the +18V or +5V supply could cause a high or low line voltage indication.

Line Voltage Indicator Chart
{| class="wikitable"
!LED2
!LED3
!Voltage
|-
|<center>On</center> || <center>Off</center> || <center>OK</center>
|-
|<center>Off</center> || <center>Off</center> || <center>High</center>
|-
|<center>On</center> || <center>On</center> || <center>Low</center>
|}

===Exploding or Damaged 15,000uf Capacitor at C11 (C10 on WPC-95)===

A smoking, domed, or in the worst case exploded filter capacitor at C11 can result from cross connecting J124 and J128 on the power/driver board. Doing so creates a circuit that routes 70VDC coil power through C11 which is typically rated at 25VDC and is meant to filter the 20VDC flash lamp circuit. This is made possible since J124 and J128 are identically implemented. Both are 5 pins wide, both keyed at pin 4. This is possible on WhiteWater, Dr. Who and Bram Stokers Dracula at least, and may also be possible on other games. It is possible on any WPC or WPC-S game that uses J124, whether or not J128 is used.

[[File:J106ConnectedToJ132BlowsC11.jpg|thumb|left|300px| J106 flash lamp power connector with red/white wire incorrectly connected to J132 on a Gilligan's Island, perhaps by Gilligan himself. Image courtesy of FB "Pinball Repair Group II" member Criss King]] 
Another very effective way to blow C11 is to connect the flash lamp power connector at J106 to high power coil grounding circuits at J132. The connectors are the same width and keyed identically. This connects 72VDC coil power to the 20VDC flash lamp power which is filtered by C11, a 15,000uf/25V capacitor, with the same results as mentioned above. 

Other possible causes for a damaged C11 are a shorted flipper coil diode, a shorted drive transistor on the FlipTronics board, or installing backbox ribbon connectors incorrectly (bottom female housing row to top male header row).

[[File:J124J128ErrorBlockingDiode.jpg|thumb|left|300px| A 1N4004 blocking diode installed in series with R224. Image courtesy of John Wart Jr.]] 
An effective method of preventing damage to C11 in the event that one of the conditions above is met, is to install a blocking diode in series with the large sand resistor at R224. Install a 1N4004 (for example) with the banded side facing the PCB as pictured at left.
 

===WPC and WPC-S Games With No Solenoid, Flasher or Feature Lamps, A Blanking Signal Issue===
[[File:SeveredBlankingSignal.jpg|300px|thumb|left|The trace emanating to the right from pin 1 in this picture has been severed by corrosion as it passes between pins 19 and 20.]] 
The blanking signal from the MPU is connected to pin 1 of each of the 74LS374 buffers (U1 thru U5 and U18) that drive general illumination, flash lamps, coils, and feature lamps. Normally, this signal is pulled low by the MPU board, indicating that no faults have been detected and the system is running as expected. Without a low blanking signal, none of the game features implemented by the driver board will be enabled.

As these games begin to age, the 12V filter cap located at C2 begins to leak it's corrosive contents onto the PCB. As noted in the section titled "[https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Check_fuses_F114_and_F115_message Check Fuses F114 and F115 Message]", the corrosion often damages adjacent parts and sometimes invades the solder mask to sever critical signals, like the blanking signal or even data signals. If continuity can not be "buzzed" between the blanking and data pins of U1 and U2, and C2 has been leaking, then there is a good chance that the signal trace has been severed under or around U1. Corrosion seems to accumulate under the chip and between the legs frequently. To address this issue, cleanly remove the chip, clean up the corrosion, rebuild traces as necessary, install a socket, and replace the 74LS374 if necessary.
 

===Solenoid, Flasher, and Motor problems===

Flashers, solenoids, and motors in WPC games are turned on via transistors on the driver board and in some games, transistors on the [[Williams_WPC#Auxiliary_8-Driver_Board_.28A-16100.29| Auxiliary 8 Driver Board]].

Before proceeding to diagnose solenoid or flasher problems, see this section: [[General#How_coils.2C_flashers.2C_and_motors_are_turned_on| How Coils, Flashers, and Motors are Turned On]].

The general logic for providing a path to ground for a coil, solenoid, flasher or motor (subsequently, we'll refer to coils only, but this is true for coils, flashers, and motors) via the driver board is as follows. Operation of the [[Williams_WPC#Auxiliary_8-Driver_Board_.28A-16100.29| Auxiliary 8 Driver Board]] is similar but control is accomplished via the long ribbon cable from the MPU to the 8-Driver Board.

#The MPU places the appropriate bit pattern on the data bus to control a "bank" of 8 transistor circuits. The data bus is extended to the power/driver board via the interboard ribbon cable.
#The MPU/ASIC "clocks" the appropriate [http://www.datasheetcatalog.org/datasheets/90/375622_DS.pdf 74LS374], an "octal latch" on the power/driver board, to latch data on the data bus into the 74LS374.
#The outputs of the 74LS374 turn on a 2N5401 transistor.
#The output of the 2N5401 turns on a TIP-102 transistor.
#The TIP-102 transistor either provides the path to ground for the waiting coil power or, for higher powered coils, turns on a TIP-36c transistor which provides the path to ground.

The reason that (up to) 3 transistors are used in the circuit is to "amplify" the power. A 2N5401 transistor can handle a comparatively small amount of current. A TIP-102 transistor can handle a much greater current load. The TIP-36c in 8 of the WPC power/driver board circuits can handle an even greater current load.

Note: With the exception of flipper coils and coils driven through the "special solenoid" drivers, diodes used to [http://en.wikipedia.org/wiki/Snubber snub] the reverse current caused by the collapse of the coil's electromagnetic field, are located on the driver board. High power and low power playfield and backbox coils (solenoids 1 through 16) should not have a diode on them. This convention eases the tech's job in that he/she doesn't need to be careful with diode orientation on the coil.

Note: Coils driven by a Flash Lamp drive (solenoids 17 through 20) or by special solenoid drives (solenoids 21 through 28) require a "tie back diode" connection. When a flash lamp drive is used, a diode must be added to the circuitry, as was done with the Terminator 2 single drop target for example, as the power/driver board doesn't include this diode. When a special solenoid drive is used, a connection from the coil, back to the appropriate pin on the driver board which leads to the on-board tie back diode, must be made. See the section [[#Blown / Failing Q20 Transistor on the Driver Board and the Tieback Diode|Blown / Failing Q20 Transistor on the Driver Board and the Tieback Diode]] below for more information

====Transistor "Quick Check"====
[[File:QuickTransistorCheck.jpg|300px|thumb|left|Testing TIP-102s quickly on a WPC power/driver board.]] 
A quick check of the TIP-102s on the driver board can save time. Set your DMM to "continuity check". Place the black lead of your DMM on board ground. Touch the tab of each TIP-102. If the meter indicates continuity, then that TIP-102 is shorted. This quick test works only with TIP-102s and NOT with TIP-36c transistors since the tab of a TIP-36c is connected differently.

For WPC power/driver boards, the lamp matrix TIP-107 transistors can also be checked using this method if the black probe is touched to the 18V test point on the right edge of the board.

[[File:YT.png]] A video demonstrating this technique on a Data East MPU can be viewed [https://youtu.be/VXiS04-yY58 here].
 

===="Help" Info Provided by WPC Games====
[[File:WPCHelpSequence.jpg|300px|thumb|right|WPC games provide help during coil test.]] 
During coil test, pressing the credit button provides a bit of information helpful in debugging your game.

With coil test "stopped", pressing the credit button sequences through the following information.
*Solenoid power and ground (drive) wire colors
*Solenoid power and ground (drive) connections
*The fuse that protects the circuit
*The sequence of cascading transistors that provide a path to ground for the solenoid. In the picture at left, Q82 (TIP-36), Q81 (TIP-102), and Q71 (2N5401) provide the path to ground.
 

====Failed TIP-36c====
[[File:WPCSolenoidGroundTraceBlownAndRepairedAnnotated.jpg|300px|thumb|left|A blown trace (inside the yellow circle) caused by a shorted TIP-36c transistor. The damage has been nicely repaired with a solid core jumper, soldered to through hole components versus "tack soldered" to the trace, making a stronger solder joint. Note: solder flux visible on replaced TIP-102 and TIP-36c later removed with isopropyl alcohol.]] 
When replacing shorted transistors, examine the traces connected to the transistor for further damage. In the picture at left, a shorted TIP-36c was replaced. During test, the first time the TIP-36c was called upon to provide a path to ground for the associated coil, the TIP-36c failed shorted again. This was caused by the blown trace. 

====Blown / Failing Q20 Transistor on the Driver Board and the Tieback Diode====
[[Image:Terminator2DiodeTiebackWireAnnotated.jpg|300px|thumb|left|The violet/orange "diode tieback" wire, attached to the power side of the drop target reset coil in Terminator 2. Photo Credit: John Wart Jr.]]
[[Image:Terminator2-Q20ViolentExposionCropped.jpg |300px|thumb|right|Q20, with a major malfunction, due to the diode tieback wire connection being missing. Photo Credit: John Wart Jr.]] 

Several games (Star Trek the Next Generation, Funhouse, Terminator 2, Indiana Jones, and The Addams Family to name a few), employ the use of a "diode tieback" system on a specific coil or motor. A diode tieback is the use of a clamping diode between the drive transistor ground and the voltage source to accommodate the reverse voltage spike induced when a coil's magnetic field collapses. While Williams moved most clamping diodes to the power/driver board, the flashlamp circuits (drives 17 through 20) don't include a clamping diode. Flash lamps don't create the same reverse voltage spike and hence, don't require a clamping diode. A tieback diode must be added to the game wiring when one of these flashlamp drives are used to turn on a coil or a motor.

The "Special Solenoid" drive circuits (drives 21 through 28) do include a clamping diode but that diode isn't connected to a voltage source. Presumably, Williams did this to provide flexibility in voltage levels used to drive a special solenoid. When one of the special solenoid drives is used to drive a coil or motor, a connection must be made from the power side of the coil or motor back to the associated power/driver board clamping diode via the appropriate header pin at connectors J122 through J126.

If the tieback diode connection is lost, the associated drive transistor on the driver board (as pictured on the right) WILL be damaged. Also, the associated coil is likely to be held on continuously and melt. In the example pictured at left from a Terminator 2, the diode tieback wire is the thin violet/orange wire. It connects from the coil power side on the drop target assembly coil lug to J122 pin 9 on the driver board and then to clamping diode D5. If the solder connection at the coil lug is solid, suspect the wire connection at the J122 IDC connector. Repinning this connection with a good quality crimp-on Trifurcon pin is advised.

The Addams Family uses Q20 for the "Swamp Release" coil, Q22 for the "Bookcase Motor", Q24 for the "Thing Eject Hole", and Q26 for the "Thing Motor", all requiring a tieback diode.

Star Trek: the Next Generation drives the subway diverters via the 8-Driver board in the upper right side of the head. These also require a tieback diode as discussed [http://www.pinwiki.com/wiki/index.php?title=Star_Trek:_The_Next_Generation#Diode_.22Tie_Back.22_missing_causes_8-Driver_Board_transistor_to_fail here].

====Coil Locks On====
This is the most prevalent problem observed (versus coil not firing). When a coil locks on, this means that the power that is present at the coil at all times has found a path to ground. Normally, a path to ground is provided via a controlled transistor set on the driver board. In rare cases a frayed wire or a wire with an insulation gap/failure will touch ground and the coil will lock on.

Most of the time, the drive transistor on the driver board has shorted internally and is acting as if it's been turned on. Should this be the case, the following steps will isolate the problem transistor.

#Use the "Solenoid/Flasher Table" at the front of the game manual to identify the likely failed transistor(s).
#Remove the driver board from the game.
#Test the drive transistor (TIP-102 or TIP-36c).

Testing a TIP-102 transistor
#Set the DMM to diode check
#Place the black lead on the center leg
#Place the red lead on each of the flanking legs in turn
#A measurement between .5 and .7 should be displayed
#Readings outside of this range (generally dead shorts) indicate the part has failed.

Testing a TIP-36c transistor
#Set the DMM to diode check
#Place the red lead on the center leg
#Place the black lead on each of the flanking legs in turn
#A measurement between .5 and .7 should be displayed
#Readings outside of this range (generally dead shorts) indicate the part has failed.

If the drive transistor tests failed, remove the part using this [http://www.pinwiki.com/wiki/index.php?title=General#Desoldering_Printed_Circuit_Board_Through_Hole_Components procedure] being very careful with the delicate traces and through holes.

Most of the time, the last transistor in the cascading transistor chain is the only one to have failed. But, it's important to test the upstream transistors before placing the board back into service. If a TIP-102 has been found to have failed, test the upstream associated 2N5401 predriver. If a TIP-36c has been found to have failed, test the upstream associated TIP-102 and 2N5401 predrivers.

[[Image:Terminator2-Q20ViolentExposionCropped.jpg |300px|thumb|left|A failure involving other parts connected to the failed transistor Photo Credit: John Wart Jr.]] Sometimes, additional parts connected to the failed transistor will have been damaged too, as pictured at left. It then becomes necessary to replace those parts, remove carbon (it's a conductor) and to rebuild burned traces as necessary.

When a coil has locked on for an extended period of time, the coil wire insulation heats up, melts, and begins to short together. Left locked on for long enough, the coil becomes a dead short. It's important to test the resistance of the failed coil to ensure that it hasn't been damaged. A resistance measurement less than 2 ohms certainly means that the coil is damaged, but comparing the coil's resistance to other known good coils is the best and easiest test. WARNING: If the coil has become a dead short and remains in circuit, and the game is powered on, the associated driver transistor WILL be damaged. 

====Coil Fails to Work====

Before proceeding, see this section: [[General#How_coils.2C_flashers.2C_and_motors_are_turned_on| How Coils, Flashers, and Motors are Turned On]].

Possible causes for coils failing to fire include:
*The switch associated with the coil is not being sensed by the MPU, and hence the MPU doesn't command the coil to fire.
*The coil doesn't have power
*One/both of the coil wires are not solidly soldered to the solder lug
*The coil winding is open
*The coil power is not finding a path to ground
*Interlock switch is not activating when pressed

=====Associated Switch Failure=====
If the MPU isn't commanding the coil to fire, obviously it won't. For instance, if a slingshot switch isn't being "made" or some other switch matrix problem prevents proper switch sensing, then the MPU won't command the slingshot coil to fire. This type of failure is easy to isolate merely by placing the game in switch test and closing the switch. Also, if during game play, points are scored when the switch closes, clearly the switch is being made. If a coil fires in solenoid test but not in game play, then the root cause is a switch problem versus a coil problem.

=====No Power to the Coil, Coil Wire not Solidly Soldered, or Coil Winding Open=====
Testing for power to the coil is easy.
*Set the DMM to DC volts. If not an auto-ranging meter, expect less than 200VDC.
*Turn the game on.
*Place the black lead on a convenient game ground like the ground braid or side rail.
*Place the red lead on the coil lug with the "fat" wire(s). The fat wire carries power to the coil.
*The appropriate voltage should be read (75VDC for coils, 20VDC for flashers)

If the appropriate voltage is not seen, there are two primary reasons. Either the power circuit fuse has blown or there is a discontinuity in the power wiring from the driver board to the coil. Turn the game off. Remove the associated fuse and "buzz" it with a DMM set to continuity test. While the fuse is out of the board, make sure it's rated at the proper amperage. Generally, WPC coil and flasher circuits are fused with a 3ASB fuse. If the fuses tests good, the next test is to ensure continuity from that fuse to the coil power lug. With the DMM still set to continuity, "buzz" between the fuse and the coil power lug. If continuity isn't proven, the task is then to find the break in continuity between the driver board connector and the coil power lug. Remember that power is "daisy chained" through several coils in the game. That is why some coils will appear to have two power wires soldered to one lug.

If the appropriate voltage is seen, then test for a break in the coil windings. With the game still powered on...

*Place the red lead on the other coil lug.
*Again, the appropriate voltage should be seen.

If the appropriate voltage is not seen, then either the coil winding has a break in it or the winding is not solidly soldered to the coil's solder tabs.

=====Coil Power is Not Finding a Path to Ground=====
The smaller wire attached to one of the coil lugs connects the coil to the driver board. The driver board has a drive transistor allocated for each coil in the game. The smaller wire must have a solid connection back to the driver board. There are two ways to test the path to ground.

#Use a DMM set to continuity to "buzz" the connection of the smaller wire between the coil and the female connector on the driver board. Ensure that the connection of the wire at the IDC connector is solid. If the coil is driven by a TIP-102 transistor, buzzing between the smaller wire on the coil and the transistor tab should show continuity.
#With the game powered on, and a short length of wire stripped on both ends, touch one end of the wire to the ground braid in the head. Touch the other end of the wire BRIEFLY to the tab of the associated TIP-102. If the coil pulls in, then the path to ground has been proven and the failure is likely the TIP-102 itself. NOTE: This test can be performed ONLY when a TIP-102 is the drive transistor. TIP-36c transistors are configured differently. The tab of a TIP-36c is not connected in the same way.

Once the wiring and connector have been verified to be in order, the next step is to test the associated drive transistor. Unlike when a coil locks on and the driver transistor has shorted on, in this case the drive transistor may have failed "open". Test the transistor using the same procedure outlined in the prior section. Replace as necessary.

If the drive transistor tests failed, remove the part using [[General#Desoldering_Printed_Circuit_Board_Through_Hole_Components|this desoldering guide]] being very careful with the delicate traces and through holes.
 

=====High Voltage Interlock Switch Failure=====
On later WPC games (beginning sometime during production of Twilight Zone in 1993), there is a push button switch used for disabling high voltage circuits (20VDC and 50VDC) when the coin door is opened, providing a measure of safety against higher voltage shocks.

Sometimes, this interlock switch can get worn or dirty (or there are problems with the movement of the internal parts), and the switch doesn't always form a closed circuit properly. So, while the coin door is closed, the interlock switch may fail to activate the 20VDC and/or 50VDC circuits.

Note that there is a separate push button switch responsible for reporting to the MPU whether or not the coin door is open in order to display the "high voltage disabled" message. So, if the high voltage interlock switch fails to complete a high voltage circuit, the MPU will have no idea about this failure, and thus not display a notification message.

To test for the issue, turn the game off, and use a digital multimeter in continuity mode across the appropriate switch lugs for the two circuits (20VDC and 50VDC) on the interlock switch. If the lugs are dirty, they may need to be cleaned. If there is black gunk that looks like it may be baked onto the lugs, it may need to be sanded or filed off to reach the bare metal of the switch lug. Once the lugs are clean and the multimeter is attached, then slowly press in the switch button. If a switch closure is not detected, there may be a problem with one of the switch's circuits. If there is only a switch closure at a certain point where the button is only pressed part way, then fails again after being pushed all the way in, there is likely a problem with the internal parts of the switch.

The switch can be opened up and inspected for issues, and possibly cleaned and repaired. Or, it can simply be replaced with an E79-00A momentary switch or E79-30A0 momentary pull-on switch (both are DPDT, 10A, 125/250v).

====Low Coil Voltage====
[[File:WPC-C8.jpg|300px|thumb|left|C8, located near the 50VDC test point, can cause reduced coil power.]] 
Coil power for WPC games is nominally about 70VDC. Very little can reduce this voltage. If the game is delivering significantly less than 70VDC, suspect BR3.

It's also possible for C8 to cause reduced voltage. C8 is a 100uf/150V (sometimes installed as 100uf/100V) capacitor.
 

====Q26 Transistor & Coil Locking On with Rottendog Driver Board====
[[File:Rottendog-wdb089-masking-error.jpg|300px|thumb|left|Masking error on Rotendog WDB089 Rev. 2]]
If the Q26 transistor (and associated coil) keeps locking on with a Rottendog WDB089 driver board, there may be an erroneously exposed trace on the back of the PCB near one of the screw mount notches that is causing a short. It is located at the bottom edge of the board near connector J122. The exposed trace is next to the grounding pad for the screw mount, and excess solder may be bridging them together.

The issue was noticed on a revision 2 board. It is not currently known if other board revisions are affected by the issue.

To address the issue, first remove any excess solder that may be bridging the connection between the exposed trace and the grounding pad. Then, seal the exposed trace with a PCB solder mask material (ie, an overcoat pen would work) or clear nail polish.
 

===Lamp problems===

Lamps (or globes for those of you in the UK) fall into two categories. "General Illumination" and "Controlled Lamps". Your game probably has other lamps which are actually "flashers" that require an 89 or 906 bulb. Flashers are covered elsewhere in this Wiki.

General illumination lamps (GI) provide the ambient lighting for the playfield, backbox, and coin door. These lamps are lit most of the time. The only "controllable" aspect of these lamps is their brightness, which of course, includes off.

Controlled lamps (sometimes called "feature lamps") are under complete CPU control via the 8-by-8 lamp matrix. These lamps illuminate the various "features" of the game such as mode inserts, pop bumper lamps, inlane/outlane insert lamps, etc.

====General Lamp Problems====
[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
WPC and WPC-95 systems employed "lamp boards" to ease the manufacturing process. These lamp board PCBs used "twist in" sockets, each with a 555 lamp. Over time, the pads on these sockets develop "divots" which sometimes results in a poor connection to the twist in socket. This can be easily corrected by removing the lamp board from the game and reflowing the solder on the pads.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
Another problem with lamp boards is the header connections. The solder joints at the connection pins often fracture due to connector insertion pressure, heat, fatigue, etc, and due to being a single sided PCB. The fix for this is again to reflow the solder around the header pins.
 

[[File:FracturedSolderJointLampBoard.jpg|300px|thumb|left|Fractured solder joints on this lamp socket caused intermittent operation.]] 
One of the less reliable designs Williams used was to "cantilever" lamp sockets over the end of lamp boards. This was done on a great many games such as Twilight Zone, Judge Dredd, etc. The repeated pressure needed to insert a new lamp into the socket causes the solder to fracture. This can be corrected easily by simply reflowing the solder at the joint. 

However in some instances, the socket has become damaged beyond the simple repair of just soldering the legs to the lamp board. Replacement sockets are available from most pinball parts vendors.
 

If after repairing the lamp board divots, reflowing the header connectors, the lamp socket is still completely intact, (the contacts do break off of the socket sometimes), and the bulb is good, suspect that the diode associated with the particular lamp may be bad.
 

====General Illumination Problems====

'''Background'''

[[File:WPCGIConnectors.jpg|thumb|300px|left|WPC/WPC-S General Illumination Connectors J119 (cabinet), J120 and J121 (repinned)]] 
The WPC power/driver board provides 5 GI circuits under CPU "brightness control". The WPC-95 power/driver board provides 3 GI circuits under CPU "brightness" control and 2 circuits that are always powered. Those two circuits are always connected to the backbox lamps. 

GI power is provided by the transformer in the form of 6.3VAC at power/driver board connector J115. Although there are five pairs of wires, they are all connected together at the transformer. One side of the AC GI circuit on the power/driver board is fused by F106 through F110 which are all 5ASB fuses. This side runs to the GI lamps, and carries 6.3VAC to the backbox, playfield, and coin door via power driver board connectors J120, J121, and J119 respectively. J119 is a 3-pin header that is always connected to the coin door lamps. J120 and J121 are electrically and physically identical (keyed at pin 4) and therefore can be connected to either the female playfield GI connector or the female backbox GI connector without care. The other side of the GI AC feed is connected to ground. 

The GI power is controlled by a triac in the return line from the playfield. When these triacs are off, no current passes and the lamps are off. When the triac is turned on, the GI lamps glow. The triac is a slightly special part - it must be a "four sector" triac. This means that it can switch both positive and negative sides of the AC cycle with only a positive signal. 

Each triac is switched on/off by a 2N5401 transistor which is controlled by U1, a 74LS374, an octal D-Type Flip-Flop with three state outputs (a fancy way of saying that the device is an 8-bit data buffer). 

U1 is "clocked" by the ASIC via the /TRIAC signal. If you have AC power present at J115, and no GI at all, it's possible that the /TRIAC signal is not getting through to U1. A logic probe applied to pin 11 of U1 will prove that the signal is getting through. If the signal is not present, try (after turning the power OFF)...
*Pressing firmly on the MPU ASIC to "reseat" it.
*"Reseating" the ribbon cable between the MPU and the Power/Driver board.
*Use your logic probe to track the signal from pin 66 of the ASIC, across the MPU to the MPU connector, across the ribbon cable, then across the Power/Driver board to U1 pin 11.

The CPU can dim the GI by switching on the GI for only parts of the AC waveform. To do this, the CPU uses a zero crossing signal on the driver board keyed from the AC that feeds the 5V circuit, diodes D3 and D38, and the LM339 at U6.

[[image:YT.png]] A video further describing operation of the General Illumination circuit can be found [https://youtu.be/RcAHeP_iTBU here].
 

[[File:WPCJ115.jpg|thumb|300px|left|WPC General Illumination Connector J115 (AC power in). Note wire colors, beginning on the bottom with a yellow/white, then three (looped) yellow, then three (looped) yellow/white.]]
[[File:WPC-GI-RepinAlternative.jpg ‎|thumb|300px|right|WPC General Illumination Connector J115 "dongle" that provides an alternative to looping wires. Two wires are crimped into 4 of the 7 .093 pins, which is much easier than crimping two wires into a .156 crimp pin. Note wire colors, with red connected to yellow/white wires and black connected to yellow wires through the connector. The center pin is used for the "ground reference". This method is identical to the method Williams used in late model WPC games, but this connector is added and moved closer to the Power/Driver board.]] 
Wire colors to J115 during the early WPC games were always yellow (AC) and yellow-white (AC return) as pictured at left. Pin 1 of J115 provides the "ground reference". Later WPC games used different wire colors at J115 and instead of "looping" power through the connector at J115, connected two wires to the same pin at the 9-pin connector between the transformer secondary and J115 (note picture at right that implements the same concept for earlier model games.

The colored wire connections for this era of WPC game are yel-wht connected to pin 1, yellow connected to pins 2-6, yel-wht connected to pins 7,8, 10, 11, & 12. Pin 9 is the key.
 

J119 is always keyed at pin 2, with a white-Violet wire at pin 1 and a Violet wire at pin 3

J120 and J121 are 11 pin connectors. Wire color/positions (when used) are identical for all WPC games and are shown in the table.

{| class="wikitable"
!<center> Pin </center>
! Wire color at J120/J121    
|-
|<center>1</center> ||  Brown
|-
|<center>2</center> ||  Orange
|-
|<center>3</center> ||  Yellow (yellow)
|-
|<center>4</center> ||  Key
|-
|<center>5</center> ||  Green
|-
|<center>6</center> ||  Violet
|-
|<center>7</center> ||  White-Brown
|-
|<center>8</center> ||  White-Orange
|-
|<center>9</center> ||  White-Yellow (yellow)
|-
|<center>10</center> ||  White-Green
|-
|<center>11</center> ||  White-Violet
|}

'''Common GI Problem Causes''' (listed by probability/ease of testing and correction)

'''GI Bulbs Not Lighting'''

Let's start by determining if the problem is "off board", i.e. not on your power/driver board, or "on board".

#Take note of the wire color of the GI string that is not working.
#Set your DMM to AC voltage. If your DMM is not an "auto-ranging" model, expect to measure about 7 volts AC.
#Turn the game on.
#Insert one probe of your DMM (either one) into the rear of the female connector position with the same wire color as noted earlier. Make sure you make contact with the conductor.
#Insert the other probe into the rear of the female connector with the white wire that has the same color "tracer" as the color noted earlier.
#You should be measuring 6 to 7 VAC.
#If there is voltage at the connector, then the problem is "off board".
#If there is no voltage at the connector, then the problem is "on board".

'''Off board GI problems'''

#'''All lamps blown.''' Don't laugh. Just for giggles, put a known working lamp into one of the lamp sockets of the suspected GI string. I've seen it more than once. Usually the result of operators never changing a bulb, or somehow connecting higher voltage to the circuit.
#'''"Open" in GI wiring.''' The GI wires leading from J120/J121 may be cut/broken between the connector and the GI lamp sockets. Remove both of the female connectors at J120/J121. Use your DMM to check continuity between the lamp socket and the appropriate wire/pin at J120/J121.

'''On board GI problems'''

#'''Blown fuses.''' This is also the easiest problem to fix. Check each GI fuse following this [[General#Testing_fuses| procedure]]. Don't trust your eyes.
<ol start="2">
<li>'''Loss of "Cross Board" Connectivity.''' This problem is generally caused by burned header pins, traces, or in some cases, poor prior repairs. Use the following table to check cross board connectivity with J120/J121 as your target. Buzz between the pins/parts shown in the table or use the diagrams below.
{| class="wikitable"
!<center> GI Connector/pin </center>
! Connects to 
! ...and to fuse 
! associated circuit wire color 
|-
|<center>J120-1</center> ||  Triac Q18 tab    ||  ||  Brown
|-
|<center>J120-2</center> ||  Triac Q10 tab  ||   ||  Orange
|-
|<center>J120-3</center> ||  Triac Q14 tab  ||   ||  Yellow (yellow)
|-
|<center>J120-4</center> ||  Key pin  ||  ||  
|-
|<center>J120-5</center> ||  Triac Q16 tab  ||   ||  Green
|-
|<center>J120-6</center> ||  Triac Q12 tab  ||  ||  Violet
|-
|<center>J120-7</center> ||  J115-3  || <center> F110 </center> ||  White-Brown
|-
|<center>J120-8</center> ||  J115-4  || <center> F109 </center> ||  White-Orange
|-
|<center>J120-9</center> ||  J115-6  || <center> F108 </center> ||  White-Yellow (yellow)
|-
|<center>J120-10</center> ||  J115-5  || <center> F107 </center> ||  White-Green
|-
|<center>J120-11</center> ||  J115-2  || <center> F106 </center> ||  White-Violet
|}
{| class="wikitable"
!<center> GI Connector/pin </center>
! Connects to 
! associated circuit wire color 
|-
|<center>J115-7</center> ||  Triac Q10 pin 1  ||  Orange
|-
|<center>J115-8</center> ||  Triac Q18 pin 1  ||  Brown
|-
|<center>J115-9</center> ||  Key pin 
|-
|<center>J115-10</center> ||  Triac Q16 pin 1  ||  Green
|-
|<center>J115-11</center> ||  Triac Q14 pin 1  ||  White-Yellow (yellow)
|-
|<center>J115-12</center> ||  Triac Q12 pin 1  ||  Violet
|}

<center>
<gallery widths=140px heights=180px perrow=5 caption="WPC-089 Power/Driver Board GI Buzz Diagrams provided by Sascha Voskuil">
File:GIBuzzBrown.jpg|<center>Brown GI String</center>
File:GIBuzzOrange.jpg|<center>Orange GI String</center>
File:GIBuzzYellow.jpg|<center>Yellow GI String</center>
File:GIBuzzGreen.jpg|<center>Green GI String</center>
File:GIBuzzPurple.jpg|<center>Violet GI String</center>
</gallery>
</center>
<center>Click on the thumbnails above for the full sized GI buzz image</center>
 
<center>The clickable images above, in an animated gif...</center>

[[File:AnimatedGIConnections.gif|center|An animated diagram of WPC-089 GI connections]]
 

[[File:J120-J121SolderPads.jpg|thumb|300px|left|Critical PCB traces for the brown and orange GI circuits that are often compromised with amateurish attempts to replace J120.]] 
Regarding poor prior rework, sometimes when J120 is replaced, the through holes at pins 7 and/or 8, are pulled causing a loss of connectivity from the board front to the board rear. This will prevent the brown and/or orange color GI circuit from working properly. Additionally, the through hole at J121, pin 6, that routes power to the 3-pin connector at J119, if pulled, will cause the cabinet GI (violet) to not light (coin door lights).
 

<li>'''Burned connectors.''' 
Over long periods of time, both the male and female GI connectors at J115, J120, and J121 often burn. 
This was especially prevalent in early WPC games like Terminator 2. 
[[File:WMS WPC Burnt GI Typical.JPG|thumb|300px|left|Typical burned connector on the output (female) side of the backbox GI on the driver board]]
[[File:BurnedJ120-121.jpg|thumb|300px|right|These female housings for J120/121 are burned so much that they are "welded" to the male headers.]]
[[File:BurnedJ120-121Rwmoved.jpg|thumb|300px|left|The connectors after removal. Get your marshmallows ready.]]
Numerous "hacks" have been employed over the years by well meaning repairmen but the only real way to fix burned connectors is to replace both the male header pins and the female housings/pins. "Trifurcon" phosphor-bronze crimp-on pins are recommended to provide a better connection at the female connector. Note that these must be phosphor-bronze (7A rating, as original). Don't buy them unless the supplier calls that out as the brass version looks the same but is only rated at 5A. If you replace burned female connectors, the male connectors are probably burned too and should be replaced. The damaged surface of the male pins will generate heat, and cause early failure of the replacement connector. Plus, the GI will be dimmer than it should be. J115 is a special case. The black Panduit connector that Williams used on many machines is far superior to any crimp pin, with a 12A rating (compared to 7A for phosphor-bronze Trifurcon pins). These, however, can be hard to find. Fortunately, they rarely burn and therefore rarely require service. Another alternative for high current connections is to use Molex MarKK series contacts (Molex part number 45570-3050) along with Molex 41695 series plugs. Although they cost more than the Trifurcon style contacts, these contacts are rated for a current load up to 13 amps.
 
WPC-089 Power/Driver Board J120/J121 connector repair parts list...

{| class="wikitable"
!<center> Qty </center>
! Part 
! Product ID 
|-
|<center>2</center> ||  11 pin .156 male header (cut to size) ||  26-48-1245
|-
|<center>2</center> ||  Connector, .156 Plug, 11 pin (Molex 41695 series) ||  09-50-8111
|-
|<center>10</center> ||  .156 Trifurcon crimp contacts for the larger gauge wires ||  08-52-0113
|-
|<center>10</center> ||  .156 Trifurcon crimp contacts for the smaller gauge wires  ||  08-52-0125
|-
|<center>2</center> ||  "Keying Pins" for Molex 41695 series plugs ||  15-04-0297
|-
|<center>1</center> ||  Crimp tool ||  1028-CT (or equivalent) 
|}
Note: Product IDs shown above can be found at http://www.greatplainselectronics.com/Category-80.asp. Other vendors may carry these same parts.
 
<li>'''Burned AC power input connector.''' There is also a 9-pin (3x3) connector between the transformer secondary and J115. This connector/pins sometimes burn and may require replacement. Check to ensure that AC power is being delivered to the power/driver board at J115.</li>
[[File:WPCGICabinetConnection.jpg|thumb|300px|left|WPC General Illumination power connection between the transformer secondary and J115 (AC power in). This picture is from a Twilight Zone, which used the newer, multicolored wires between this connector and J115 on the power/driver board.]]
*Set your DMM to AC voltage. If your DMM is not an "auto-ranging" model, expect to measure about 7 volts AC.
*Turn the game on.
*Insert one probe of your DMM (either one) into the rear of the female connector at J115, pin 3.
*Insert the other probe into the rear of the female connector at J115, pin 11.
*You should be measuring 6 to 7 VAC.
*If no voltage is present, examine the 9-pin connector between the transformer secondary and J115, pictured at left.
 
<li>'''Burned traces.''' Usually, this is a secondary problem created after the connectors burn. Visual inspection of the traces might uncover the problem, but "buzzing" them for continuity is the best practice.</li>
<li>'''Failed 2N5401.''' These don't fail very often, but are easy to test following this [[How_to..._(solder,_desolder,_"stitch",_test_transistors,_test_ICs,_etc)#Testing_a_Transistor.2C_Silicon_Controlled_Rectifier_.28SCR.29_or_Field_Effect_Transistor_.28FET.29| procedure]].</li>
<li>'''Failed resistors.''' Again, these don't fail very often but are easy to test with your DMM. Keep in mind that "in-circuit" measurements may not be reliable.</li>
<li>'''Failed 74LS374.''' This is rare too but easy to test following this [[How_to..._(solder,_desolder,_"stitch",_test_transistors,_test_ICs,_etc)#Testing_an_integrated_circuit | procedure]]. You can also test the outputs of the LS374 by probing pins 2, 5, 6, 16 and 19 with your logic probe. At full GI brightness (8), these pins should test as solid "low". At the dimmest GI brightness (1), the above referenced pins should all be pulsing "high". Additionally, pin 1 of the LS374 should always test low and pin 11 should always be pulsing "high".
</li>
<li>'''Failed Triac.''' These rarely fail. But, if you've gotten to this step in the procedure, it's time to replace the Triac. Remember, you need a 4-sector triac.</li></ol>

As these boards age it is easy to pull out the little copper hole liners that connect traces from one side of the board to the other. If you install new connector pins, be sure to check continuity from the new pins onto the board somewhere. This only takes a couple minutes and can save you a lot of time.

=====GI Lamps Not Dimming=====

[[File:WPC089BlankingTraces.jpg|thumb|300px|right|Small traces leading from the through holes of BR2's AC solder pads (pads circled) can be easily damaged, causing GI lamps to not dim. On this board revision, the upper/right through-hole has a small trace on the solder side of the board that connects to the "via" visible to the left of the through-hole. These traces lead to vias which can be seen just SouthWest of R194.]]
The primary cause of GI lamps failing to dim is broken traces at BR2, usually caused when BR2 was replaced. These traces lead to D3 and D38. Both of these traces must be intact for dimming to work as they supply the power to generate the signal to the Zero Cross circuit (ZC) which is key to dimming.

Before you go too far diagnosing the hardware, if your WPC game will not dim the general illumination, make sure that Standard Adjustment #25, "Allow Dim Illum.", is set to "YES". If set to "NO", then the GI will never dim, even during General Illumination test.

General dimming "theory of operation"...
*The driver board generates the ZC signal with the BR2, D3/D38 and U6 circuitry (different resistors).
*The ZC signal is connected to the ASIC (across the driver board, the ribbon, and then across the MPU).
*The ASIC uses the ZC signal to determine when to send the /TRIAC signal to U1 pin 11 (an 74LS374 buffer IC) as it simultaneously presents GI string enable data on the data bus.
*U1 latches GI string enable data from the MPU's data bus.
*The output of U1 forms signals T0 thru T4, which enable the TRIAC circuitry.
 

[[File:ZC_broken.jpg|thumb|300px|left|This is the ZC signal from a Doctor Who with a broken trace between the two 270 ohm resistors after D3. Dimming did not work in this example.]]
[[File:ZC_ok.jpg|thumb|300px|right|This is the ZC signal from a properly working Twilight Zone with General Illumination dimming working correctly.]] 
It is possible that D3, D38 (1N4004 diodes) or the LM339 at U6 have failed. If the ZC test point on the power/driver board is not strobing (which can be seen with a logic probe), something upstream of the test point has failed.

U6 is an LM339 comparator. The resistors around it (R16 and R17, both 230 ohm 1/4 watt) help generate the correct ZC signal. If a resistor is burned or out of spec, or if a trace is broken in the circuit (there are several "vias"), then ZC may still strobe but in an incorrect way which the ASIC doesn't recognize as the zero cross signal.

The ZC may be strobing, yet the GI still won't dim. Use a logic probe to test both sides of diodes D3 and D38 as it is necessary for both the positive going and the negative going portions of the AC sine wave to be detected. If the traces buzz out back to BR2, then suspect one side of BR2 being open. Incredibly, it is possible for the game to work correctly in all regards other than GI dimming with half of the bridge open. Odd...but it happens.
 

====WPC-95 General Illumination Problems====
[[File:WPC95GIToast.jpg|thumb|300px|left|The GI section of a WPC-95 driver board with 6A2 diodes installed. Note the significant burn around the diodes as well as the melted connectors and burned pins.]] 
The General Illumination circuit for WPC-95 games is very similar to WPC games. When the WPC-95 system was implemented, Williams reduced the number of "dimmable" GI circuits from 5 to 3, with 2 of the circuits being lit at all times. Within the two "always on" GI circuits, Williams placed 8 large 6A2 diodes, to create a voltage drop in the circuit which would dim the lamps slightly and presumably lengthen lamp life. However, these big 6A2 diodes create a great deal of heat. Without a heat-sink like those used on the TRIACs, the high heat they produce causes the printed circuit board and traces to burn. Later versions of the WPC-95 driver board replaced these 6A2 diodes with zero ohm jumpers.
 

[[File:WPC95GIJumpers.jpg|thumb|300px|left|The back side of a WPC-95 driver board with jumpers installed across the GI circuit.]] 
You can (and probably should) remove the 6A2 diodes, and either replace them with zero ohm jumpers, or, more easily, implement the solution pictured at left. This solution bypasses the diodes completely, by installing the following jumpers.

*J103 pin 11 jumped to J105 pin 5
*J103 pin 12 jumped to J105 pin 6
 

<center>
<gallery widths=160px heights=280px perrow=5 caption="WPC-95 Power/Driver Board GI Buzz Diagrams provided by Sascha Voskuil">
File:Wpc95PinWikiGI-String1-Brown.png|<center>Brown GI String</center>
File:Wpc95PinWikiGI-String2-Orange.png|<center>Orange GI String</center>
File:Wpc95PinWikiGIString3-Yellow.png|<center>Yellow GI String</center>
File:Wpc95PinWikiGI-String4-Green.png|<center>Green GI String</center>
File:Wpc95PinWikiGI-String5-Purple.png|<center>Violet GI String</center>
</gallery>
</center>
<center>Click on the thumbnails above for the full sized GI buzz image</center>
 
<center>The clickable images above, in an animated gif...</center>

[[File:Wpc95PinWikiGI-1-5.gif|center|An animated diagram of WPC-95 GI connections]]
 

====Controlled Lamp Problems====

===== Twist Socket Lamp Not Lighting =====
[[file:wpc-lamp-board-twist-sockets.jpg|thumb|right|300px|A lamp board with twist sockets found in Terminator 2]]
Two things that can fail on lamp boards are individual lamp circuit diodes or the solder pads can develop "divots", where the twist sockets make physical contact with the board. To overcome the divots, simply add a little solder, and carefully reflow the solder pads. Make certain not to apply too much heat...just enough to evenly flow the solder.

With Fire!, a system 11 game, Williams started using lamp boards with .156" header connections for the lamp column and row lines. This allowed for easy removal and service of the lamp boards. However, it introduced some new problems. Because the lamp boards used were single-sided, (this was presumably a cost analysis decision), the .156" header pins can develop cold solder joints and crack due to vibration. The problem can easily be rectified by removing the old solder from the header pins and applying fresh, new solder.
 

<center>
<gallery widths=300px heights=300px perrow=2 caption="Typical issues with lamp board sockets and headers">
File:PCBMountLampDivot.jpg|<center>"Divots" in the connection pad of a "twist in" lamp.</center>
File:WPCPCBLampBoardHeaders.jpg|<center>The solder on these header pins has been reflowed nicely.</center>
</gallery>
</center>

The following actions can help debug an individual socket failure:
# Move the non-working twist socket to another spot that is working. This will test that the bulb and socket itself are working. If not, replace the bulb, try to adjust the socket's contact legs, try to clean off the contact points if they are dirty, and if all that fails, replace the twist socket.
# Move a working twist socket into the position that is not working. If the socket works, the original socket may have been the problem. If the working socket also does not work in the non-working position, there is likely a problem with that position.
# Check the connector, especially if it is an IDC connector. Sometimes a wire can pop out and lose connectivity.
# Remove the lamp board. Check the header pins for cracked solder joints and reflow the solder as necessary. Reinstall and test.
# [[General#Testing_a_Diode|Test the diodes with a multimeter]]. If any are bad, replace them. Make sure to orient the diode the same way that is indicated on the silkscreen. It's sometimes possible that a previous owner installed a diode the wrong way.
# Sometimes the pads on the lamp board that the socket makes contact with get dirty or worn enough to put a divot in the metal. Clean off the contacts, and if that doesn't improve anything, tin the pads with a thin layer of solder.
# If none of this was successful, test for continuity between the lamp board and the driver board.
# If wiring continuity checks out, [[#Controlled_Lamp_Operational_Description|troubleshoot the issue like any other controlled lamp]].
 

===== Controlled Lamp Operational Description =====

WPC feature lamps are controlled from the WPC MPU and ultimately enabled via the driver board. The control signals are as follows.
#The 68B09EP places a data bit pattern on the data bus. This represents the lamp column to be strobed.
#The bit pattern is conveyed to the driver board via the ribbon cable between J211 on the MPU and J113 on the driver board.
#U9 on the driver board (a 74LS240) buffers the column bit pattern for U18 (a 74LS374).
#The ASIC on the MPU asserts the /LMP COL signal which "clocks" the data into U18 by pulsing pin 11.
#U18 outputs are connected to the ULN2803 at U20, which inverts the signal and enables one of eight TIP-107 Darlington transistors (Q91 thru Q98) that enable 18VDC to flow to the enabled column. This completes the column "strobe" portion of lamp matrix operation.
#The 68B09EP places a data bit pattern on the data bus. This represents the lamp rows to be strobed.
#The bit pattern is conveyed to the driver board via the ribbon cable between J211 on the MPU and J113 on the driver board.
#This bit pattern data is presented to four 74LS74s (Dual D-Type Flip-Flops) at U10 thru U13. This sets up a path to ground for the 18V lamp matrix power for each row enabled by the bit pattern
#The ASIC on the MPU asserts the /LMP ROW signal which "clocks" the data into U10 thru U13 via their "reset" signal inputs.
#The (not) Q signal of each 74LS74 enables one of eight TIP-102 Darlington transistors (Q83 thru Q90) that provide the actual path to ground (through a .22 ohm 1 watt resistor) for the 18V lamp matrix power.
#At this point, current flows from the enabled column circuitry, through the game wiring to the lamps, then through the row circuitry to ground for the rows that are enabled.
#The row enable signal is switched off when the LM339 comparators at U15 and U16 detect a voltage rise above the reference voltage present at pins 5, 7, 9, and 11 of both LM339s, via the "set" signal of each 74LS74 (U10 thru U13).

This process repeats itself over and over with the MPU cycling through columns 1 thru 8 while enabling specific rows, lighting lamps at the intersection of the enabled column and the enabled rows.

[[Image:WPC089AlkalineDamagedLampMatrixEnable.jpg|300px|thumb|right|The column trace between the J211 dual row header and the ASIC chip socket (pin 63) clearly corroded away. The lamp row trace is immediately below the column trace and unaffected.]]
There are many possible causes for lamp matrix malfunctions. Some reasons, in order of probability are:
#Lack of 18V lamp matrix power. If LED6 is not lit, or TP8 shows other than 18V, "buzz" F114 for continuity with your DMM. If F114 is blown, test BR1 using the method specified [http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Bridge_Rectifier here].
#Failure of the row (TIP-102) or column (TIP-107) drive transistor. Both of these are easily diode tested and compared to the other 7 row/column drive transistors.
#For a column failure: Failure of the ULN-2803 at U19. U19 works the same as U20 in the switch matrix, providing a periodic pulse to all columns.
#For a row failure: Failure of a 74LS74 at U10/11/12/13. Again, these parts can either be diode tested for, better yet, use a logic probe to see if they are delivering the necessary pulses. Compare the operation of similar pins.
#Failure of the associated .22 ohm 1 watt resistor in the path between 18VDC lamp matrix power and ground (R150 for example).
#Poor connections between J211 on the MPU and J113 on the power/driver board. Sometimes, reseating the ribbon cable on both ends will "fix" the issue. Replace the ribbon cable and examine the dual row headers if the problem becomes chronic.
#Prior work on the power/driver board. The data bus runs completely across the power/driver board, stopping in at several 74LS374s (U1 thru U5) along the way. The signals pass through the board from component side to solder side at U9. If the same column and row of the lamp matrix are not lighting (i.e. column 5, row 5), it's a good bet that the signal for that row/column is compromised in the area of U9. The traces at each IC are delicate and it's tough for most hobbyists to remove a 20 pin IC without damaging the traces. It's particularly vexing to encounter a problem where a data signal is held low or high by one of the 74LS374s since each data signal is connected to all of them and even using [diode test] sometimes can't identify the faulty IC. Some techs will cut the data signal pin close to the PCB for a 74LS374, using the process of elimination to identify the culprit (not recommended). Enough said, but it's easily seen that power/driver boards can be damaged quite easily by the novice. Send it to a pro.
#Fatigued connections between the ASIC on the MPU and it's chip socket. Since the ASIC provides critical enable signals for the lamp matrix, reseating or [https://www.greatplainselectronics.com/Information.asp?region=139 retensioning] these pins is reasonable course of action. [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Removing_the_ASIC Use a PLCC removal tool] to safely remove the ASIC without damaging the socket.
#Failure of any of the ICs noted above. Each of these ICs can be tested with a DMM set to [http://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit diode test]
#Corrosion on the MPU that might have compromised the enable signals, as seen in the picture at right. Corrosion can and will attack under the header pins at J211 on the MPU.
 

'''Quick Test of Lamp Column Transistors'''

[[Image:CheckingLampColumnDriveTransistors.jpg|300px|thumb|left|"Quick Test" for a shorted lamp column transistor.]]
If the game has an entire column of lamps locked on, there is a good chance that a lamp column transistor has shorted. Testing for this condition is very simple. Set your DMM to continuity. Touch one probe to the 18V lamp matrix test point as pictured at left. Touch the other probe to the tab of each of the TIP-107 transistors. Any that "buzz" are shorted and will need to be replaced.
 

'''General Lamp Matrix Testing'''

The control logic for the WPC lamp matrix can be tested by connecting a spare lamp using two jumper wires. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example applies to WPC-089 power/drive boards. The procedure is the same for WPC-95 power/driver boards, but the connector designations and transistor numbers differ. Images authored by Sascha Voskuil, used with permission)

 
<center>Testing a working lamp matrix circuit on a WPC-95 Power/Driver board
[[File:LampMatrixGeneralTesting.gif|center|General testing of the lamp matrix circuit on a WPC-95 Power/Driver board. All columns operating normally.]]

 
Column 4 shorted in the lamp matrix circuit on a WPC-95 Power/Driver board
[[File:LampMatrixColumn4Shorted.gif|center|Testing the lamp matrix circuit on a WPC-95 Power/Driver board that has column 4 shorted.]]

 
Column 4 inoperative in the lamp matrix circuit on a WPC-95 Power/Driver board Note: In this animation, columns 4 and 2 are inoperative. 
[[File:LampMatrixColumn4Inop.gif|center|Testing the lamp matrix circuit on a WPC-95 Power/Driver board that has column 4 open (inoperative).]]
</center>
 

We provide this section for completeness knowing that WPC games offer independent lamp row and column tests as part of the diagnostics. 

'''Testing the lamp matrix columns:'''

[[Image:Placeholder.jpg|300px|thumb|right|Jumper connection for testing lamp matrix columns.]]
Use the following procedure to test the TIP-107 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to block current flow and prevent interaction between the lamps in the matrix. In this test we are connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to power/drive board connectors J133/134/135 (row) and J136/137/138 (column).
#Unplug all connectors with red or yellow wires leading to them. These are the lamp matrix connections (lower right corner of power/driver board)
#Turn the game on and start "All Lamps" test in the Test/Diagnostic Menu.
#Clip one end of the test jumper to J137 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to J133 pin 1, the rightmost pin on the connector
#The test lamp should flash to indicate that the column driver is working.
#Repeat the test for the pins 2 through 9 on J137. There is no pin 8 as it is the key.

If a column doesn't light or is stuck on, reference the lamp matrix table in the manual to identify the transistor to test.

The following table shows the lamp number and driving transistor for each of the column pins.
{| class="wikitable"
!   Pin   
!Wire Colors
!Lamp number
!Transistor number
|-
|<center>J137-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q98</center>
|-
|<center>J137-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q97</center>
|-
|<center>J137-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q96</center>
|-
|<center>J137-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q95</center>
|-
|<center>J137-5</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q94</center>
|-
|<center>J137-6</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q93</center>
|-
|<center>J137-7</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q92</center>
|-
|<center>J137-8</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>J137-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q91</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:Placeholder.jpg|300px|thumb|right|Jumper connection for testing lamp matrix rows.]]
Use the following procedure to test the TIP-102 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to power/drive board connectors J133/134/135 (row) and J136/137/138 (column).
#Unplug all connectors with red or yellow wires leading to them. These are the lamp matrix connections (lower right corner of power/driver board)
#Turn the game on and start "All Lamps" test in the Test/Diagnostic Menu.
#Clip one end of the test jumper to J133 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to J137 pin 1, the rightmost pin on the connector
#The test lamp should flash to indicate that the column driver is working.
#Repeat the test for the pins 2 through 9 on J133. There is no pin 3 as it is the key.

If a row doesn't light or is stuck on, reference the lamp matrix table in the manual to identify the transistor to test.
The following table shows the lamp number and driving transistor for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Lamp number
!Transistor number
|-
|<center>J133-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q90</center>
|-
|<center>J133-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q89</center>
|-
|<center>J133-3</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>J133-4</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q88</center>
|-
|<center>J133-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q87</center>
|-
|<center>J133-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q86</center>
|-
|<center>J133-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>J133-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q84</center>
|-
|<center>J133-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q83</center>
|}

===== Lamp Issue Caused by Connecting "Growth" Connectors =====
[[File:WPCErroneousConnection-1.jpg|300px|thumb|left|A misplaced connector on Judge Dredd. Image courtesy of Chuck Sanderson, CP Pinball]]
[[File:WPCErroneousConnection-2.jpg|300px|thumb|right|The connector, not connected, as it should be.]]
[[File:LampMatrixHeadache.jpg ‎|300px|thumb|left|Lamp Matrix failure "map" created when J136 is erroneously connected on Judge Dredd]]

An issue that seems to come up fairly often is caused by literally placing a square peg into a round hole.

The images shown here from a Judge Dredd shows a "growth" connector wired from the factory that was never used during production. It happens to be in the proximity of J136, a lamp matrix connector and the wires are lamp matrix wires (colored red and colored yellow). One could almost be forgiven for forcing the female housing onto J136 even though the connector types are different.

With this connector in place, all kinds of lamp matrix havoc ensues as shown in one lamp matrix "error map" shown at left.

The solution is simple. Remove the connector.

All images provided by Chuck Sanderson, [https://cppinball.com/ CP Pinball]
 

===Switch Problems===

Switches in WPC games fall into two categories, those within the switch matrix, and "direct" switches.

====Diode and Switch Matrix Wiring Orientation on a Microswitch====
[[File:Submicro Switch Wiing.jpg|300px|left|thumb|Typical wiring for any Microswitch]]
First and foremost, all switches located in the switch matrix MUST have a diode. Secondly, the diode has to be installed in the correct orientation. If a diode is installed "backwards", the end result my be that all of the switches in that particular row get triggered or even stranger issues occur. Finally, the diode legs must not be connected to any of the other wires or terminals of the switch, or the switch will funk up the switch matrix.

Here is the correct orientation for the wiring and the diode on a microswitch. The white wire w/ trace and non-banded side of diode is connected to NC terminal. The banded side of diode is connected to common terminal. Finally, the green wire w/ trace is connected to NO terminal.
 

====Built-in Switch Testing====
WPC games monitor switch closures as the game is played. If a switch is not activated after a certain number of balls (usually 30, but will vary depending on the switch in question), the game will show the "credit dot", an indication to the operator that a switch may be faulty. Some switches are not often closed (like switch 55 located in the White Water pop bumper garden) and some switches simply aren't hit by rookie players (like the upper exit to the Twilight Zone mini playfield). Some switches will be marked non-operational immediately after a certain event where the switch is known to have been activated (switches related to The Shadow's brick wall drop target are one example; any error in the lock sequence causes the credit dot to light immediately). 

There is a table held in RAM that contains counters for all monitored switches. Each ball served decrements the counter for each switch; as soon as that switch is hit on the playfield, the counter is reset to the initial value. The credit dot gets lit when any counter for any monitored switch goes to zero. Switches such as flipper optos are set to very low initial values, as flippers are hit on every ball. It would have been possible to have higher values set for switches that would occasionally be activated but not often by novice players as noted above, however this aspect of the programming was rarely if ever used. 

When a credit dot is lit, often the game will offer "switch compensation", which was a Williams' patented feature, that allowed a nearby or alternate switch to achieve the same result as hitting the original, marked non-operational, switch. This enabled a game with faulty switches to still be played close to the original gameplay. Sometimes the faulty switch will auto-clear itself when activated, but more often than not, the fault would have to be cleared manually. To clear a switch manually, enter the "Switch Edges" test (as described below), and manually activate the switch. If the switch in question is functioning properly, activating the switch will remove the credit dot. 

The first action to be taken is to enter diagnostics. The game will indicate the reason(s) for the credit dot on the display, upon pressing the enter button on the coin door to receive a test report. 

Since the normal switch matrix is 8 by 8, games like Twilight Zone, Star Trek: The Next Generation, and Indiana Jones employ a 9th column of switches. These switches are tested via a dedicated switch test tied to the playfield feature. An example is the Star Trek: The Next Generation cannon switches. 

=====T.1 Switch Edges Test=====
[[file:WPCSwitchTestExample.jpg|400px|thumb|left|An example switch matrix display, this one from Twilight Zone. Note the opto switches in column 7 (for example) are shown as boxed dots.]]
Switches can be tested by entering Test T.1, Switch Edges. Switch Edges Test presents an 8 by 8 switch matrix grid with one or two switch columns outside of the matrix. The additionally columns are for dedicated switches. The left column is for switches located on the coin door (all WPC games), and the right column is for flipper cabinet and flipper EOS switches (WPC games which use a Fliptronics board - Addams Family and newer). Open switches show as a simple dot on the DMD. Closed switches show as a boxed dot on the DMD. Microswitches and leaf switches will show as a dot when open. Optos will show as a boxed dot when the opto beam is not being broken. The last closed switch name and number will be shown on the display along with the two wire colors that are connected to that particular switch. While in switch edges test, manually closing properly operating switches will be shown on the display. 

=====T.2 Switch Levels Test=====

====Direct Switch Problems====

'''Direct switch operation'''

Direct switches include:
*Left coin chute
*Center coin chute
*Right coin chute
*4th coin chute
*Service Credits/Escape (referred to as "escape" here)
*Volume down/Down
*Volume up/Up
*Begin Test/Enter

Direct switches are not part of the WPC switch matrix. All of the direct switches are located on the coin door, and connect to the MPU at J205. The MPU senses these switches individually, and apart from the switch matrix. Therefore, isolation diodes are not used with direct switches.

Normally, with the switch open, the LM339s at U16 and U17 compare 12V (supplied on the MPU to both the switch and to the LM339) with 5V (as a comparison level) and signals the 74LS240 at U15 that the switch is open. When the switch closes, it shorts the 12V to ground and the comparison at the LM339 then indicates to U15 that the switch is closed. U15 is "clocked" by pin 48 of the ASIC (SW DIR), causing U15 to present its data to the data bus. The 6809/ASIC "debounces" the switch. Debouncing is not a factor to be considered here and doesn't factor in switch testing at all.

'''Direct Switch Pinout at J205 for both WPC and WPC-S MPUs''' 
Notes: 
:J205, pin 5 is the "key" pin.
:J205, pin 10 provides ground (black wire)
:J205, pin 11 is unused
:J205, pin 12 is an "enable" back to the coin door interface board 

{| class="wikitable"
!Signal
!Wire color at J205
!MPU pin
!Diode
!LM339 & input pin
!U15 input pin
|-
|Left chute || <center>orange/brown</center> || <center>J205-1</center> || <center>D15</center> || <center>U17-5</center> || <center>11</center>
|-
|Center chute || <center>orange/red</center> || <center>J205-2</center> || <center>D16</center> || <center>U17-7</center> || <center>13</center>
|-
|Right chute || <center>orange/black</center> || <center>J205-3</center> || <center>D17</center> || <center>U17-11</center> || <center>15</center>
|-
|4th chute || <center>orange/yellow</center> || <center>J205-4</center> || <center>D18</center> || <center>U17-9</center> || <center>17</center>
|-
|Escape || <center>orange/green</center> || <center>J205-6</center> || <center>D11</center> || <center>U16-9</center> || <center>2</center>
|-
|Down || <center>orange/blue</center> || <center>J205-7</center> || <center>D12</center> || <center>U16-11</center> || <center>4</center>
|-
|Up || <center>orange/violet</center> || <center>J205-8</center> || <center>D13</center> || <center>U16-7</center> || <center>6</center>
|-
|Enter || <center>orange/gray</center> || <center>J205-9</center> || <center>D14</center> || <center>U16-5</center> || <center>8</center>
|}

'''Debugging direct switch problems'''

To discover the problem as quickly as possible, we'll divide the problem into smaller pieces. We must first determine if the problem is on the MPU board or the problem lies with the wiring to the coin door and/or the specific switch. If your MPU has obvious alkaline damage at U15, U16, or U17, address the alkaline damage first.

Begin testing with the game OFF.

'''Isolate the problem to the MPU or to the game wiring/switch '''
#Remove connector J205 from the MPU.
#Build a jumper wire with alligator clips on both ends.
#Clip one end of the jumper wire to the game's ground braid in the game head.
#Turn the game on
#Carefully touch the other end of your jumper wire to the appropriate pin on J205 as shown in the table.
#If the MPU carries out the function of the switch, the problem is not on the MPU.
#If the MPU does nothing, the problem is on the MPU.
#Skip to the appropriate section below.

'''Identifying problems NOT on the MPU '''

'''Test the direct switch's path to ground '''
#Your game should still be turned off.
#DMM set to continuity.
#Clip the black lead of your DMM to any game ground, like the lockdown bar or ground braid.
#Red lead on the solder joint between the switch and the black wire that provides ground.
#You should hear "tone". If not, further diagnose the break in the black wire between the solder joint and game ground.

'''Test the direct switch itself '''
#Black lead of your DMM still clipped to game ground.
#Red lead on the solder joint opposite the black wire (or bare wire jumper) of the switch under test.
#Depress the switch. You should hear "tone". If not, the switch is defective and not "making". See the section below that describes cleaning these switches.

'''Test the signal path to the MPU '''
#Clip the black lead of your DMM on the solder joint opposite the black wire (or bare wire jumper) for the switch under test.
#Remove the connector plug at J205 from the MPU.
#Red lead on the appropriate pin of J205 for the switch under test. See the table above. It's easiest to access the pin through the rectangular hole in the back of the connector where the pin's "tang" snaps in.
#You should hear "tone". If not, there is a discontinuity in the wire between the direct switch and J205. Note that the coin door interface board is between these two points. The coin door interface board is a "pass-through" for these signals and rarely causes a problem. Still, reseating connectors J1, J3, and J4 on the coin door interface board might uncover the problem. More likely, the wire between J1 on the coin door interface board and J205 has a break in it.

'''Identifying problems on the MPU '''

'''Test the signal path through J205 and onto the MPU '''
J205 is right below the battery holder and as such, sometimes receives the unwanted gift of dripping alkaline from depleted batteries. Carefully examine both the male and female connections of J205 for alkaline "greenies". Assuming no alkaline damage... 
#Begin with your game turned off.
#Connect J205 to the MPU.
#Clip the black lead of your DMM to the solder joint opposite the black wire (or bare wire jumper) for the switch under test.
#Red lead on the banded end of the appropriate diode shown in the table above.
#You should hear "tone". If not, there is either a problem with the physical connection at J205 or the alkaline "greenies" are sneakier than you gave them credit for. Re-examine J205 and the surrounding area of the board for alkaline damage. The traces from the switch connectors are very small and it takes very little alkaline damage to compromise them. You may also re-pin the female side of J205.

At this point, a logic probe would be the best tool to use. You can pick up 5V power for your probe across the electrolytic cap at C31 which is immediately to the right of the battery holder. Black lead on the negative side (top of the cap). Red lead on positive side (bottom). The board is silkscreened with polarity markings. Set the logic probe to "CMOS" test mode, as you will be measuring 12VDC.

If you don't already have a logic probe, you should. Although for this test, you can still get by with your trusty DMM. Clip the black lead of your DMM to game ground. The ground braid in the head is a good place to pickup ground at this point. Set your DMM to DC volts.

'''Test the LM339 inputs '''
#Start with the game turned off.
#Again, set your logic probe to "CMOS"
#Clip one end of your jumper wire to the appropriate pin of J205. Leave the other end of your jumper wire unconnected, but handy as you'll touch it to ground later.
#You now need to turn the game ON.
#Measure the signal at the appropriate LM339's appropriate pin shown in the table above. Either place your logic probe on the pin or place the Red lead of your DMM on the pin. The signal should measure high (or about 12VDC with your DMM).
#Now, with your other hand, touch the free end of your jumper wire to the ground braid in the backbox as you observe the results.
#You should see the signal transition to low. If you still measure high, then the pin isn't being grounded correctly. Candidates are a failed diode/resistor in the circuit, the board trace between the diode and the LM339 is compromised, or a badly failed LM339.

'''Test the LM339 outputs/74LS240 (U15) inputs '''
#Set your logic probe back to TTL as you will be measuring 0 - 5V signals
#Measure the signal at the appropriate pin (see table) of U15. The signal should measure high (or about 5VDC with your DMM).
#Touch the free end of your jumper wire to the ground braid in the backbox as you observe the results.
#You should see the signal transition to low. If you still measure high with the jumper wire grounded, then either the LM339 outputs have failed, the board trace between the LM339 and U15 is compromised, or the 74LS240 has failed and is corrupting the signal. You can test U15 using the procedure in the "How to..." section of PinWiki, [https://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit here].

The output side of U15 can't be tested effectively since that is the processor/ASIC data bus and should be constantly and irregularly changing states.

If you've followed this process step-by-step, you should have identified the problem with the signal and will be able to effectively perform the appropriate repair.

'''Cleaning direct switches'''

Coming soon...will describe disassembly and cleaning...
Sometimes, several rigorous open/close cycles will "clean" corrosion from the switch.

====Switch Matrix Problems====

'''Isolate the problem to the MPU or to the game wiring/diodes/switches '''

Follow these steps to determine if the switch matrix problem is on the CPU or somewhere in the game wiring.

#Remove connectors J206/J207, J208/209 and J212 from the bottom of the CPU (J206 and J207 are electronically the same and J208 and J209 are electronically the same).
#Clip one lead of a test jumper to pin one of J207 making sure you don't touch any of the nearby pins on J207.
#Power the game on, and enter Switch Edge test (you've left J205 on the CPU so the diagnostics switches still work).
#Touch the other end of the jumper to pin one on J209, then pin two and so on. You should see (and hear) the CPU indicate that switches #11, #12, #13, etc. are being "made" as you touch the pins of J209. You should *never* see multiple switches being made.
#Move the jumper from J207 pin 1 to pin 2. Re-test to every pin on J209, listening for the machine to read every switch as closed. Continue in a similar manner testing each pin of J207 to every pin in J209.

The following images, provided by Sascha Voksuil, grapically depict the above tests of the on-board switch matrix circuitry with a jumper wire. A diode is not required since the test jumpers directly from a single pin to a single pin. Remember, the purpose of switch diodes is switch isolation. Also, have no fear conducting this test. Unless you connect one end of the wire to high voltage, nothing can be damaged.

[[File:Switch matrix test ROWs1-8 with COL1.gif|left]][[File:Switch matrix test COLs1-8 with ROW1.gif|right]]
 

If only one switch shows on the Switch Edge test for each pin combination, then the CPU's switch matrix is working properly and you can confidently assume that any switch problems lie elsewhere. Possibilities include a shorted wire, bad/broken/shorted diode, bad under playfield opto board, bad coin door interface board, etc. If the problem is observed with row 2 of the switch matrix, and you're game has a "-1 Power/Driver" board installed (the one with the flipper power relay), it is possible that one/both of the 4N25 opto-isolators on the power/driver board have failed. These opto-isolators communicate flipper switch closures for pre-FlipTronics games.

If multiple switch closures are reported when you touch one pin of the connector, or if the CPU reports a row or column short, then there is a fault with the switch matrix circuitry on the CPU board itself. Be aware that an additional fault may still be present on the playfield. Switch matrix chips do not simply blow for no reason!

<center>
<gallery widths=200px heights=200px perrow=3 caption="Blown ULN2803 (U20) Examples">
File:BlownULN2803.jpg|<center>An obviously blown ULN2803 (U20) caused by shorting 50V coil power to the switch matrix. Ouch!</center>
File:WPCBlownULN2803.jpg|<center>Another obviously blown ULN2803...happens all the time...Don't work on your game with power on.</center>
File:WOCBlownU14.jpg|<center>Another obviously blown ULN2803...the HV jolt also took out U14, a 74LS374 which buffers the ULN2803 from the processor data bus.</center>
</gallery>
</center>

Catastrophic Failure of ULN2803 or Other Switch Matrix Parts

[[Image:CoilLugShortedToMetal.jpg|200px|thumb|left|Example jumper connection for testing the switch matrix. Image courtesy of PinSider "sturner".]]
[[Image:CoilWrapperRubAE-23-800.jpg ‎|200px|thumb|right|A coil wrapper that has rubbed through to the copper windings due to long term vibration against a loose screw used to secure the coil bracket. This coil is from the "Thing Kickout" in The Addams Family. It electrified the entire "thing" mechanism box and caused the ULN2803 to be destroyed. Image courtesy of JT Amusements.]] 
One fairly common reason that a ULN2803 or other switch matrix circuitry may blow is a short to coil power. In the picture at left, the coil that actuates the "Bridge Diverter" on the game Twilight Zone, is touching the coil bracket on one side. Since coil power is present at both coil lugs (which is normal), a coil lug touching metal will conduct coil power to that metal. In this case, the coil bracket touches the bridge diverter piano wire and then the coil diverter and then the entire wireform. If a switch matrix solder tab or switch blade metal shorts to the wireform, poof! Get ready to replace the ULN2803.

Another way for HV to destroy the ULN2803 and other switch matrix circuitry is shown at left. Here, the coil wrapper has worn through, and then the enamel coating on the coil winding rubbed away, causing a short of coil power to the coil bracket. Just as the instance above showed, this places coil power onto the coil bracket and anything touching it, including switches.
 

===== MPU Circuitry Switch Matrix Problem Diagnosis =====

====== Quick Switch Column Strobe Testing ======

[[File:WPCSwitchColumnStrobeBenchTest.jpg|200px|thumb|left|Testing the switch column strobes quickly with a logic probe. The picture also shows a convenient place to connect logic probe power leads.]] 
A quick way to test that switch column strobes are working properly, is to use a logic probe as shown in the picture at left. Each pin of J206/J207 (all WPC MPU versions) should be pulsing high. 

====== Further MPU Circuitry Diagnosis ======

The following image (authored by Sascha Voskuil, used with permission) will help diagnose particular ICs at fault on the MPU.
[[File:WPC-089MPULayout.jpg|200px|thumb|left|Color Coded Switch Matrix Circuitry.click image to enlarge]] 

Let's use the diagram above to walk through a simple "on board" switch matrix issue.

A board presented with very slight alkaline damage to U20, the ULN2803. After socketing, and replacing the ULN2803, column 3 still failed to strobe. We used out logic probe to determine that pin 16 of U20 was strobing. Therefore, there MUST have been an on board fracture of the trace. Setting our DMM to continuity, and buzzing between J206 pin 3 (marked with a gray "3" in the diagram) and U20 pin 16 failed. Moving our probe from J206 pin 3 to the junction of R69 and C13 (also marked with a gray "3" in the diagram) succeeded. However, buzzing between the junction of R69/C13 and U20 pin 16 succeeded. Using this information, we must conclude that the discontinuity in the trace was between J206 pin 3 and the junction of R69/C13.

[[File:WPCSwitchMatrixCorrodedTraceAnnotated.jpg|200px|thumb|left|A look under connector J206 showing alkaline corrosion damage. This caused column 3 of the switch matrix to malfunction.]] 
The picture at left shows the problem. Once the J206 header was removed, we could see that alkaline had dripped onto the connector and leached down to the solder joint. The corrosion etched enough of the trace away to prevent connectivity.
 

[[File:WPCSwitchMatrixHeaderCorrosion.jpg|200px|thumb|left|A different board, with a similar problem at the header pins...]]
[[File:WPCSwitchMatrixConnectorCorrosion.jpg|200px|thumb|right|...and the matching female housings.]] 
The picture at left shows another WPC-089 MPU board with a similar problem, but much worse. This board was the victim of dripping alkaline which invaded the trace which runs under the "C17" label to J206-9 and J207-9.

The picture at right shows the female connector housings that were the victim, and transportation medium, for the alkaline corrosion. The connector on the left required repinning. The connector on the right showed only light damage which was cleaned up with a vinegar swab.
 

[[File:ImprovedSwitchMatrixDiagram.jpg|200px|thumb|left|Switch Matrix Circuit Operation. Note: Colors are coordinated with the prior diagram (authored by Sascha Voskuil, used with permission). Click image to enlarge.]]
 

===== Switch 11 or Switch 12 Reported as Closed With All Switch Matrix Connectors Removed =====
A seemingly impossible behavior can be caused by a failed 4N25 Opto Isolator on a "-1" version of the WPC Power/Driver board including RottenDog Power/Driver boards. After removing all switch matrix connectors (not the direct switch connector) from the MPU, switch 11 and/or switch 12 will be reported as closed. This can also lead to all of column 1 being reported closed when any switch is closed outside of column 1. All of the column that switch is in will also be reported as closed.

The 4N25s can be tested as described below.

Another quick test is to remove the ribbon between the MPU and the Driver board. This prevents the driver board from reporting closed switches.

===== Cabinet Flipper Switch Detection Problem Diagnosis for Pre-FlipTronics Games =====

[[File:WPCOptoIsolators.jpg|200px|thumb|right|Dual 4N25 Opto Isolators on the "-1" version of the WPC Power/Driver board can be seen in the top center of this picture (two 6 leg ICs at U7 and U8).]] 
Pre-FlipTronics games detect closure of the flipper cabinet switches via two 4N25 Opto Isolators on the "-1" version of the power/driver board. If the "cursor" can't be moved during entry of HSTD initials or if the cabinet flipper buttons don't control video mode correctly, there is a good chance that one/both of the 4N25 opto isolators is shot. Games that shipped with the "-1" Power/Driver board include:
*Funhouse
*Harley-Davidson
*The Machine: Bride of Pin*Bot
*Gilligan's Island
*Slugfest
*Terminator 2: Judgement Day
*Hurricane
*Party Zone
 

[[File:WPCEarly-1PowerDriverBoard4N25.jpg|457px|thumb|left|Illustration provided by, and used with the permission of, Sascha Voskuil aka "Zaza"..]] 
The image at left illustrates the switch matrix connection between the 4N25 Opto Isolators on the Power/Driver board and the MPU board.
 

[[File:WPCSwitchRowSchematicError.jpg|457px|thumb|left|Illustration provided by, and used with the permission of, Sascha Voskuil aka "Zaza".]] 
Note that some revisions of the WPC schematics contain an error, as illustrated by the image at left.
 

Fortunately, testing an opto coupler is simple using the diode test function provided by most DMMs. Set the DMM to diode test, compare results against those pictured below (this test conducted on a 4N25 contained on a System 11 Interconnect Board).

<center>
<gallery widths=200px heights=200px perrow=4 caption="Testing a 4N25 Opto Coupler">
File:4N25Internal.jpg|<center>The internal schematic of the 4N25. Pins 1 and 2 connect to an internal diode (LED). Pins 4 thru 6 connect to a PNP photo transistor.</center>
File:4N25Test3.jpg‎|<center>Testing the diode connected to pins 1 and 2. Red on pin 1, black on pin 2</center>
File:4N25Test2.jpg‎|<center>Testing part of the photo transistor. Black on pin 5, red on pin 6</center>
File:4N25Test1.jpg‎|<center>Testing part of the photo transistor. Black on pin 4, red on pin 6</center>
</gallery>
</center>
 

====== Special Note regarding RottenDog Power/Driver boards manufactured prior to February, 2012 ======

[[File:WPCRottenDog4N25Error.jpg|300px|thumb|left|Illustration provided by, and used with the permission of, Sascha Voskuil aka "Zaza".]] 
RottenDog aftermarket power/driver boards manufactured prior to February, 2012 contain a trace layout/connection error that exchanges the function of the two 4N25 Opto Isolators on the board. That is, the 4N25 that should report a left flipper closure actually reports a right flipper closure, and vice-versa. This error can be corrected via two cuts and two jumpers, as illustrated in the image at left.
 

[[File:WPCRottenDog4N25ErrorCorrected.jpg|300px|thumb|left|Image provided by, and used with the permission of, PinSider "troxel".]] 
Shown at left is the correction implemented by PinSider "troxel".
 

[[File:WPCRottenDog4N25ErrorCorrected1.jpg|300px|thumb|left|Image provided by, and used with the permission of, PinSider "troxel".]] 
The same image, annotated by Pinsider "zaza", calls out the need for caution when making this mod. As can be seen, 75VDC is present in the area. A better implementation might be to route the jumper wires around the 4N25 instead of under it.
 

==== WPC95 Flipper Cabinet Switch Processing====

[[File:WPC95CabinetSwitchCorrosion.jpg|200px|thumb|left|Corrosion between pins 9 and 10 on this WPC-95 MPU caused a short between cabinet flipper switch circuits resulting in both flippers actuating when either cabinet switch was closed.]]
[[File:J212Corrosion.jpg|200px|thumb|right|Corrosion on some of these pins caused erratic cabinet switch operation.]] 
The WPC-95 system implementation moved the cabinet flipper button and EOS switch sensing from the FlipTronics II board to the MPU board. Simple voltage level comparison via LM339s senses shorts to ground for those switches. The connector that cabinet switch wiring is connected to (J212) is directly below the battery holder where leaky batteries can "drip" onto the connector, corroding both under the connector and the pins on the connector. Corrosion can cause many odd problems. If this happens, the corrosion can cause the flipper buttons to be sensed intermittently and/or incorrectly.

Pictured at left is one case of corrosion impacting flipper operation. The corrosion caused the circuit to sense that both of the cabinet flipper buttons had been pressed when only one had been pressed. Standard alkaline corrosion cleanup takes care of this issue.
 

====Opto Switches====

=====Basic Operation=====
Williams opto switches are comprised of a "transmitter" and a "receiver" opto, which are each unique parts. This is different from later Sega and some Stern game systems where the optos that serve as transmitter and receiver are identical.

The transmitter opto is housed in a white plastic frame. It is powered by unregulated 12VDC. If the opto is good, measuring either solder joint of the opto should read about 12VDC as long as the game is turned on.

Note that the ball trough uses these opto transmitters also. Orient the ball trough transmitter flat side as is silkscreened on the board.
{| border="0"
|[[file:OptoTransmitter.jpg|200px|thumb|left|The solder side of a typical Williams opto transmitter.]]
|[[file:OptoTransmitterLED.jpg|200px|thumb|right|The component side of a typical Williams opto transmitter. When replacing the opto, orient the flat side toward the "K" (equivalently, orient the "short" leg of the opto toward the "K")]]
|}

The receiver opto is housed in a black plastic frame. This "IR detector" opto conducts the 12VDC supplied to it, as long as the transmitter's "light" is cast upon it. Once the transmitter light is removed, the opto no longer conducts the 12VDC. Typically, circuitry on an "opto switch board" interprets the lack of 12VDC using an LM339 comparator, and indicates that the switch is open. Remember that the "sense" of opto switches is reversed from regular "hard" switches such as leaf switches and micro-switches.

Note that the ball trough uses these opto receivers also. Orient the ball trough receivers flat side so that the leg on the flat side is furthest away from the "ear" that is silkscreened on the board.
{| border="0"
|[[file:OptoReceiver.jpg|200px|thumb|left|The solder side of a typical Williams opto receiver.]]
|[[file:OptoReceiverLED.jpg|200px|thumb|right|The component side of a typical Williams opto receiver with an aftermarket receiver LED. When replacing the opto, orient the flat side toward the "C" (equivalently, orient the "short" leg of the opto toward the "C"). OEM LEDs have an "ear" that matches the silkscreen on the board]]
|}

=====Opto Testing=====
[[file:OptoTestingWithDigitalCamera.jpg|200px|thumb|left|Testing an opto "sending" unit with a digital camera. This opto pair senses "Rudy Hits" in Funhouse. The white opto housing can be seen (upside down)]] 
The "sending side" or transmitter side of an opto pair, which should be housed in a white plastic frame, can be tested with just about any digital camera. In the picture at left, an iPhone camera was used to clearly see the purplish glow of a working opto sender.

The "receiving side" of an opto pair, which should be housed in a black plastic frame, can be tested with just about any strong incandescent flashlight. Note that an LED flashlight does not typically work too well for this test. Place the game in switch test. Block the sending opto that would normally illuminate the receiver under test. Shine your bright incandescent flashlight on the reciever opto. The switch state as shown on the display should change.
 

=====7 Opto Board Testing=====
[[File:7OptoBoard.jpg|300px|thumb|right|An example WPC 7 Opto Board, as found in AFM, WH2O, and many other WPC games.]]
The 7-Opto Board (A-14977, A-15576, A-15595) pictured at right, can be tested "in-situ" with a simple jumper wire and a DMM.

'''Procedure''' 
Test the LM339 comparators

#Place the game into switch test (T.1)
#Remove the balls from the game to prevent them from crashing down on the playfield (or stuff a rag into the ball loading hole)
#Place the playfield in the vertical position
#Remove the J2 connector on the 7 opto board
#Clip one end of a jumper to J2/pin 10
#In turn, touch the other end of the jumper to pins 1 through 7 of J2
#With each connection, a opto switch activation should be enunciated on the display
#If all 7 switch activations are enunciated, this proves that all of the LM339 comparator circuits are working.

Test the 12VDC power supply circuits
#Set a DMM to DC volts (less than 20 if not using an auto-ranging DMM)
#Remove the J1 connector
#Clip the black lead of a DMM to J1/pin 10 (ground)
#With the DMM red lead, measure DC voltage at pins 1 through 8 (excluding pin 4)
#Each pin should measure about 12VDC
#If all 7 pins measure about 12VDC, this proves that each of the 12V power circuits (and the 270 ohm current limiting resistors) are working.

If a game opto pair fails to function properly, yet both of the above tests pass, then either the opto transmitter or receiver has failed or the wire/connector connection between the opto board and one/both playfield optos has failed.

==== "Jittery" Opto Switches ====
It is possible for all opto switches in the game to act erratically. This can be difficult to diagnose because the problem can manifest itself in various ways during game play. For instance, the bulldozer blade in "Roadshow" may occasionally be unable to find it's home position. Or, the auto launcher in "Twilight Zone" may seem to want to launch a ball when none is present. Since the cabinet flipper switches are sometimes optos as well, the game's flippers may also behave strangely.

The first step is to check the optos in switch edge test. If the optos appear to blink on and then off, when the actual physical state of the opto is open, suspect an issue with the unregulated 12VDC voltage.

Measure for about 12VDC at TP1 on the power/driver board. If the voltage is significantly below 12VDC (i.e. around 10VDC) then there may be a problem with the bridge rectifier at BR5 or the 15,000uf filter capacitor at C30. Examine the solder joints at C30, especially if that capacitor has been replaced in the past. A damaged through hole may effectively remove the filter cap from the circuit, AC voltage will remain in the power circuit, and the optos will be flakey.

Use your DMM to [http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Bridge_Rectifier test the bridge rectifier] and to "buzz" between the solder joints at the cap and the appropriate legs of BR5. If this connection is flakey, repair it using a [http://www.pinwiki.com/wiki/index.php?title=General#Repairing_traces_or_creating_a_.22solder_stitch.22 solder stitch] or connect jumpers from the C30 to BR5.

====Other Switch "Jitter" Reasons====

[[File:WPC-C2-Leaking.jpg|200px|thumb|left|A leaky electrolytic cap at C2 caused the "digital" 12V to drop to about 10.5VDC.]] 
The electrolytic cap C2 in the regulated 12VDC circuit leaks quite often, eroding the traces, sometimes severing the connection completely and sometimes reducing the 12VDC power output to something lower. This can wreak havoc on the switch matrix as the regulated 12VDC is used by the LM339 comparators on the MPU board to detect switch closures. Normal cleanup procedures can be used; wipe clean, sand as necessary, retin traces, and replace the cap with a 100uf/35VDC cap (an upgrade).
 

==== Sub-microswitch Issues ====

[[file:WPCMicroSwitch.jpg|200px|thumb|left|A typical micro-switch and wireform.]] 
Some WPC games have an issue with micro-switches that are heat damaged during game assembly. When soldering the wire lead(s) onto the switch, flux leaches into the switch body and, over time, causes the switches to become "sticky".

Game switches from smoky environments often become intermittent or fail. You may be able to repeatedly actuate the switch with your finger and get it to work for a game session, but when you return to the game later, the switch will have failed again.

Tightening the screws too tightly on the switch can damage the switch internals making the switch intermittent.

The switches in games that were played on location for many years simply wear out.

When micro-switches are damaged or past their useful lifetime, there is nothing to repair, adjust, or clean inside them. Simply replace them for reliable operation. You can purchase generic switch bodies and transfer the wireform carefully to the new body.
 

====Switch Wiring====

[[File:SwitchWiringSchematic.jpg|left|thumb|200px|Williams Individual Switch Connection Schematic. The green wire is the switch column. The white wire is the switch row.]] 
Williams switches are always wired the same. The white (plus tracer) colored wire (row) always attaches to the same solder lug as the NON-banded end of the diode. The green (plus tracer) colored wire (column) always attaches to a lug by itself. The banded end of the diode always attaches to a lug by itself. This creates the following circuit, shown schematically at left.
 

The picture gallery below provides an example of correct wiring for different types of switches.

<center>
<gallery widths=300px heights=300px perrow=3 caption="Connections for Various Types of Williams Switches">
File:StandUpSwitchWiring.jpg|<center>Slingshot Switch. The Green and White wires go off-frame to the other slingshot switch in the pair.</center>
File:StandUpSwitchWiring-A.jpg|<center>Standup Target</center>
File:PopBumperSwitchWiring.jpg|<center>Typical Pop Bumper Switch</center>
File:MicroSwitchWiring.jpg|<center>Older Style Micro Switch</center>
File:SubMicroSwitchWiring.jpg|<center>The Pervasive Sub-MicroSwitch</center>
File:ReedSwitchWiring.jpg|<center>Reed Switches, as found in Cactus Canyon and NBA Fastbreak. The diodes are located elsewhere.</center>
</gallery>
</center>
 

===Display problems===
Display problems are usually the result of failing dot matrix displays themselves, flakey ribbon cables or connectors, ribbon cables installed "one row off" (or even one column off), failing high voltage sections of the dot matrix controller board, and rarely logic IC problems on the dot matrix controller board.

Start by checking the easy things first...

#Reseat the narrow ribbon cable between the DMD controller board and the DMD.
#Reseat the wide ribbon cables from the MPU to the DMD controller.
#Ensure each ribbon cable is correctly mated, and not "one row off" or even "one column off".

====Display Panel Problems====

The display panel itself may have problems. The glass component has a limited life. The continued electrical discharge releases gases inside the display, which eventually stop the pixels from glowing, and the dots will slowly fade over time. If the voltages are too high, the panel will show sparkles, clouds or ghosting.

====DMD Repair Warnings====
'''''Be careful when repairing the DMD Controller Boards, you are dealing with High Voltages when the boards are running'''''.
A good safety measure is to put one hand in a back pocket (or behind your back) when testing voltages.

It's also fairly easy to lift traces on the PCB or ruin the 'through holes' when removing components. If this happens, you may have to check continuity and 'stitch' the component hole with a thin wire strand. It's a good idea to practice on some useless PCB boards first, before taking on the DMD Controller Boards. For details on a stitch see the [[General#Repairing_traces_or_creating_a_.22solder_stitch.22| "How to Stitch"]] section of the Wiki.

'''If you do not have decent soldering and de-soldering skills, DMD HV work should be left to a professional.'''

'''HV Repair Kits and advice are available from''':
[http://www.greatplainselectronics.com Ed at Great Plains Electronics]
*[http://www.greatplainselectronics.com/proddetail.asp?prod=WPC95-HVP-KIT WPC-95 HV REPAIR KIT]
*[http://www.greatplainselectronics.com/proddetail.asp?prod=WPC-HVP-KIT WPC HV REPAIR KIT]
* ''GPE kits do not contain capacitors, which can be ordered separately as needed''.

'''HV Repair Kits and advice are also available from''':
[http://LockWhenLit.com Rob Anthony at Pinball Classics]
* [http://LockWhenLit.com/Products.aspx WPC-95 or WPC HV REPAIR KIT]
* ''Indicate in the notes section of the order if you need the WPC or the WPC-95 HV kit, Pinball Classics kits do contain the 150µF 160V capacitors''.

Bally/Williams and Data East have similarities with the 128x32 display and the display itself is interchangeable between manufacturers. DMDs have a limited lifetime and will eventually outgas. Please see the [[Data_East/Sega#Score_Display_Issues | information about outgassing displays]] in the Data East section.

====Testing DMD Controller Power====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|200px|thumb|left|Testing DMD Controller voltages at the display]] 
After you've checked the easy things, measure the voltages supplied by the DMD controller to the DMD display panel. To test the DMD controller voltages, first open the backbox, and rest the DMD panel face down on the glass. The simplest place to test the voltages provided by the DMD controller is at the display end of the power wire bundle as shown in the picture. SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you! 

[[File:OverDrivenDMDDisplay.jpg|200px|thumb|left|A manifestation of overdriving a DMD with too much voltage.]] 
Most high voltage problems are lack of the proper voltage levels. This results in no display at all. It is possible however, for the high voltage circuitry to fail in such a way that too much voltage is supplied. Or, a game might be jumpered for a lower expected voltage but connected to higher voltage. This manifests as a "plasma" or "cloudy" look on the display, as shown on the left. Note that this looks very much like an outgassed display. 

[[File:WPCDotPowerTest.gif|200px|thumb|left|Testing AC input voltages to the DMD Controller board. Click on the image to show the animation. Image provided by Sascha Voksuil aka Pinsider Zaza.]] 
If the display image has a "plasma" affect or a "cloudy" look, it's a good idea to test the input voltage to the DMD Controller board, as depicted in the animated image at left. Nominal voltages are 80VAC and 100VAC. If measurements indicate voltages significantly higher than the nominal voltages, ensure the voltage select jumpers are correct, as discussed [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Primary_Voltage_Selection_Jumpers_at_the_Transformer here].
 

The dot matrix display needs three voltages to operate. Williams designed the DMD controller to drive the the DMD display panel just a bit below its specified voltages, presumably to extend the life of the panel. You can find the specification of a panel [http://www.vishay.com/docs/37006/apd128g.pdf here].

Place the black lead of the DMM under the ground braid in the game's head or use clip leads to secure the black lead to ground. Remember, you are working one-handed, so this becomes a necessity. Place the red lead of your DMM on each of the pins supplying power as shown in the picture. At some point in the production of DMD controllers, Williams changed the Anode and offset voltages from about -124VDC and -112VDC to about -112VDC and -100VDC. As long as there is a 12VDC difference between the Anode and 12VDC offset voltages, your DMD controller is providing correct voltage levels.

{| class="wikitable"
!Function
! J604 Pin 
! Spec 
! nominal WPC voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>-110V</center> || <center>'''-112V'''</center> ||  -124V in early DMD machines
|-
|  12VDC Offset  || <center>2</center> || <center>-98V</center> || <center>'''-100V'''</center> ||  Must be 12V less than anode voltage. Will be about 20V less than anode voltage if display not connected
|-
|  Key || <center>3</center> || || ||
|-
|  Ground || <center>4</center> || || ||
|-
|  Ground || <center>5</center> || || ||
|-
|  5VDC || <center>6</center> || <center>5V</center> || <center>'''5V'''</center> ||
|-
|  12VDC || <center>7</center> || <center>12V</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>75V</center> || <center>'''62V'''</center> ||  Williams runs this voltage low
|}

If the high voltages are off by more than a few volts, turn the game off, disconnect the power connector at the DMD controller, and test the voltages at the DMD controller male header pins. If the voltages return to nominal WPC voltages, the zener diodes on the DMD controller are probably OK but the resistors and transistors around them are suspect. As shown in the table above, if DMD controller power is not connected to the display, the nominal 12VDC offset will be about 20VDC.

Note that a failing or failed DMD display glass can drag these voltages down. Before you begin any work on the DMD controller board, perform the above test with the DMD display power disconnected. If the voltages return to nominal WPC voltages, it's possible that your display is the culprit. Test the DMD controller with a known good display to isolate the fault to either the DMD controller or the display panel.

[[File:LowHVSupply.jpg|200px|thumb|left|Measuring for 62VDC, and finding only 19.95VDC. The result of this low component of the high voltage trio can be seen in the picture. The manifestation is similar to an outgassed display. The display is showing "FREE PLAY".]] 
For the 62V and -112V circuits Williams used a relatively sophisticated regulator circuit. The problem is, the resistors and diodes dissipate quite a lot of heat. In a warm operating environment, this leads to burned components and circuit boards. The board traces are often weakened. Repair in the area is tricky.

Here's a description of the function of the parts in the -112V circuit.

Q1 is an output buffer. It just follows the voltage set at the top of zener diode D2.
Q2 and Q3 form a constant current 5mA driver for the diode.
Q2 is a current control for D2. By pulling on the base of Q2, the zener current can be reduced to compensate for the diode leaking as it
warms.
Q3 is a current sensor for D2. Note the very low 120 ohm resistor. If D2 passes more than 5mA, Q3 will start to turn on, and reduce the current through the diode by pulling on the base of Q3. So the zener diode always operates at 5mA.

The transistors can be tested in circuit, just watch out for the 120 ohm resistors across the base and emitter of Q3.

The board is subject to transistor shorts, which can also blow out the resistors. Open resistors are a common problem if Q2 and Q3 are bad.
 

====Slow Animations====
[[File:Pre-DCSSoundCardSolderBridge.jpg|thumb|200px|left|A solder bridge formed on a pre-DCS sound card, affecting speed of display animations.]] 
Slow animations along with sound synced to the animation is a very unusual problem. It is caused by a manufacturing defect in pre-DCS sound boards. As shown at left, an imperfect solder mask led to a solder bridge connecting pins 31 (R/W, read/write) and 34 (FIRQ) on the solder side of the sound board. By connecting the FIRQ signal and the R/W signal, the whole system slows down due to extraneous FIRQ interrupts to the MPU ASIC. The correction for this is straightforward, remove the solder bridge. 

[[File:TZSlowAnimations.jpg|thumb|200px|left|A screen shot from the YouTube video showing slow animations on a Twilight Zone.]] 
[[File:YT.png]] A YouTube video of this problem can be found [http://www.youtube.com/embed/gThgBHVuwio?autoplay=1&rel=0 here].

A PinSide thread leading to this solution can be found [http://pinside.com/pinball/forum/topic/tz-slow-dmd-animations-and-parts-suggestions here]. 

===="SuperScript or SubScript" Characters====
One of the more interesting display failures is the appearance of characters on some display formats that appear to be shifted up/down 1/2 character or SuperScripted/SubScripted. The cause of this failure is not the display or the dot controller. This failure is caused by a poor connection between the ASIC on the MPU board and it's socket. Reseating the ASIC generally solves this problem. You can "retension" the ASIC leads using this [http://www.greatplainselectronics.com/tech_wms_asics.asp method] provided by Ed at GPE.
<center>
<gallery widths=300px heights=200px perrow=2 caption="Super/Subscripted Characters">
File:DisplaySuperScript.jpg|<center>Superscripted characters...</center>
File:SubscriptNoFear.jpg|<center>No Fear subscripted characters...</center>
File:DisplaySubScript.jpg|<center>Subscripted characters...</center>
</gallery>
</center>
 

==== "Rolling" Horizontal Line on WPC-95 Display ====
This problem resembles an old CRT with a vertical hold problem. A wide horizontal line "rolls" through the display from top to bottom.

This problem is easily rectified by replacing C28 and C42 on the Audio/Video board. The original value of these radial capacitors was 150µF/160V. If the original valued capacitors can't be located, the more common 220µF/160V cap is a good replacement.
 

==== Outgassing Displays ====
[[File:OutGassedDMDDisplay.jpg|200px|thumb|left|An "outgassed" display on a Williams FishTales during display test (all pixels should be on except the single vertical line). This display took several minutes to "warm up". The plasma seemed to "float" with various portions at the top of the display appearing dark.]] 
:DMDs will eventually fail. It is important to replace an outgassing display as they place extra strain on the power supply, and will eventually damage the power supply. One sign of an outgassing display is that areas of the display need to 'warm up' before becoming fully bright or that the display will remain completely blank for a few seconds and then appear normal.

Outgassing displays look very much like a display that is being overdriven by too much voltage. The acid test is to measure the high voltage using the technique described later in this section. 

==== Display is "delayed" after turn on ====
There are cases of import machines incorporating an aftermarket circuit that delays the DMD display from appearing for a fixed amount of time after the game is booted. This was done by some operators so that serial number and location information could not be ween when the machine is powered on, thereby preventing identification of a game and potential sales/operation outside a given geographic area. This circuit will not damage anything but is not standard. More information about this can be found in a [https://groups.google.com/d/topic/rec.games.pinball/Q7_FezXgJ7Y/discussion rec.games.pinball discussion.]
 

===="Snow" on Display====
"Snow" in this case means rapidly flowing, left to right, "sprays" of dots, almost like can be seen when "spraying" the gun while moving it left to right in Attack from Mars video mode, but much faster.

The cause of this in at least one case was found to be a failed 74HC74 (dual D-Type Flip-Flop) at U4. Pin 5 is the "serial clock" signal to the DMD display. Diode testing indicated that the gate had failed. Replacement of the IC returned the board to normal service.

====Fuse F601 or F602 blows====
[[File:WPCDMDControllerBridgeTestingStep1.jpg|200px|thumb|left|Testing the bridge, step 1, red lead on negative.]] 
The WPC DMD controller rectifies AC voltage via two small 1 amp bridge rectifiers. If a bridge shorts, generally the associated fuse will blow. Sometimes the current draw on the other side of the bridge is so great that the fuse blows too. Whatever the reason, the bridge can be easily tested using the same general bridge testing technique.

The pin layout for these small bridges is different from the larger 35A bridges on the power/driver board.

Begin with your DMM set to diode check, and the red probe on the leg marked with a negative sign as shown in the picture at left. Placing the black lead on each of the AC legs in turn should yield a reading between .5 and .7 volts. If your measurements fall outside of this range, replace the bridge.
 
[[File:WPCDMDControllerBridgeTestingStep2.jpg|200px|thumb|left|Testing the bridge, step 2, black lead on positive.]] 
Next, move the black probe to the leg marked with a positive sign as shown in the picture at left. Placing the red lead on each of the AC legs in turn should yield a reading between .5 and .7 volts. If your measurements fall outside of this range, replace the bridge.
 

[[File:ArcToGroundBlowsF601.jpg|200px|thumb|left|The circled area clearly shows where this trace arced to ground.]] 
Another reason for F601 to blow is shown at left. Some revisions of the DMD Controller routed the trace from one side of BR1's AC power to F601 too close to the lower right screw that secures the board to the backbox ground. If the star washer for this screw bites through the solder mask, this creates a direct path to ground, blowing F601, as it should. This can be corrected by either leaving the screw out, using a nylon washer, or using a nylon screw. Any of these three methods will work fine.
 

====Schematic Diagram for WPC and WPC-95 DMD Controller Board====
This link explains my experience repairing a Twilight Zone ('93 WPC) DMD Controller Board.
Also repaired the actual display PCB, which was damaged from a from a faulty +62v circuit:

[http://www.firepower.2ya.com/4-TZ-dmd-repair.html TZ DMD Controller Board Repair]

Schematic for DMD HV section WPC only (adapted from TZ manual):
[http://firepowerpinball.com/2ya/tz/wpc-dmd-hv-tz.pdf WPC DMD HV]

Schematic for DMD HV section WPC95 only (adapted from AFM manual):
[http://firepowerpinball.com/2ya/tz/wpc95-dmd-hv-afm.pdf WPC95 DMD HV]

Here’s a schematic with a list of the parts needed for both WPC and WPC-95 high voltage section repairs. the two boards are similar in the high voltage regulation sections.

[[File:DotControllerHVIcon.jpg|200px|thumb|left|Click on the hyperlink at right for the .pdf of this circuit.]] 
http://www.pinwiki.com/wiki/images/e/e6/Wpc-dmd-hv-all.pdf
 

[[File:WPC-089-HV-CheatSheet.jpg|200px|thumb|left|Click on the hyperlink at right for the .pdf HV section cheatsheet.]] 
http://www.pinwiki.com/wiki/images/c/cd/WPC-HV-Section.pdf
 

Another area which will help with troubleshooting the DMD Controller Board can be found in the DE section of the PinWiki (DE copied the Williams board designs), [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#PS_520-5047-01_-_High_Voltage_Missing_at_the_DMD_display Data East High Voltage Repair].

The following images of a fairly crispy WPC-089 DMD controller will assist you in ensuring that all traces are repaired.

<center>
<gallery widths=300px heights=200px perrow=2 caption="DMD Controller, High Voltage Section Parts removed">
File:DMDControllerFrontSideTraces.jpg|<center>Front side traces. The yellow line shows where a trace had burned off of this board.</center>
File:DMDControllerRearSideTraces.jpg|<center>Rear side traces.</center>
</gallery>
</center>
 

==== Heat Damaged Trace Under R9 ====
[[File:WPCDotControllerRoastedTrace.jpg|200px|thumb|left|The burn spot in the center of this picture obliterated the trace that runs from R3/C4 to R11, indicated by the yellow line.]] 
Resistor R9 eats a lot of current and becomes very hot, especially as the associated circuit components age. This damages the trace and PCB beneath it, sometimes to the extent that the trace is severed. "Buzzing" the connection between C4 and R11 is a simple test to ensure continuity of this trace.
 

====Failed RAM====
Most failures of the DMD controller that are not attributed to the high voltage section are caused by failed 6264 static RAM at U24. Since the RAM is very susceptible to electrostatic discharge, they are often damaged by improper handling. Sometimes, they just fail. Failure of this RAM manifests in many ways, including some shown below. At the very end of "display test" the MPU performs a read/write test of the RAM. If the MPU is able to communicate properly with the DMD controller, writing to and reading from the 6264 at U6, then the message "RAM TEST OK" is shown on the display. Any other message indicates a failure of the test. Test failure may be due to the I/O buffers on either the MPU or the DMD controller, the ribbon cable, or the actual RAM.

[[File:YT.png]] A YouTube video of a successful display test can be found [https://www.youtube.com/watch?v=-IK6PZL8I5o here].

====Page Errors====
There are 2 pages of 16 memory locations (0 to 15) stored in RAM on the DMD controller board. In the Display diagnostics it will run the page test and display any possible faults on either the low page or the high page (page 1 and 2 respectively) If you are only seeing errors on page 1, look to change out U33, most likely at least one output stuck high (pins 2,7,10,15). Page 2 errors the likely culprit is U35. Both devices are 74LS175. If you are seeing the same errors on both page tests, most likely it will be U16, a 74LS157, which is the A/B selector between the two page addresses.

Page errors will also throw up a RAM address error. The RAM is not at fault, just how it is addressed by the page selectors. It should clear after attending to the above

'''Note:''' the coin door buttons for advance/go back can be held down to quickly move through display test. 

<center>
<gallery widths=350px heights=100px perrow=2 caption="Various display issues resulting from failed 6264 RAM on the WPC-089 DMD Controller board.">
File:BadRAM-1.jpg|<center>Example 1</center>
File:BadRAM-2.jpg|<center>Example 2</center>
File:BadRAM-3.jpg|<center>Example 3</center>
File:BadRAM-4.jpg|<center>Example 4</center>
File:BadRAM-5.jpg|<center>Example 5</center>
File:Blown6264.jpg|<center>This random pattern caused by a blown 6264 RAM. It was blown by sending Flipper Coil power (nominally 70VDC) down the data lines (D0-D7).</center>
File:BadRAM-7.jpg|<center>Example 7</center></gallery>
</center>
 

====Failures of Various Logic ICs on the DMD Controller====
The following images represent various failures associated with specific ICs on the DMD Controller board. Of course, the specific way that an IC fails will influence what is displayed. That is, your mileage may vary. 

[[File:WPCDotControllerU1Failure.jpg|400px|thumb|left|]] 
U1 - 74HCT138 - evenly distributed non-moving "snow"
 

The display works in the game and attract-mode but in the test menu it shows nothing. U31 and/or U32 was defective. Think the opposite when the display shows nothing its worth to go into the test because possible it shows only the test.

When the display shows nothing but the data between U31 and U32 seems to be good and also there is data on BD0...BD7 to U29. Test Pin 2 of U29. If there is no clock then follow the line in the schematic to U20. There must be a clock at Pin 1. If no clock coming out from U17 Pin 9 the display shows nothing. After replace U17 the clock signal was there but corrupted from IC U4. After replace U4 too the DMD controller works.

The display shows nothing. The following lines send data to the display SERIAL_DATA SERIAL_CLOCK COLUMN_LATCH ROW-WRITE but ROW-DATA is static High or Low. U13 was defect.

 

===Sound problems===

Before going any further, check all of the basics in the [http://www.pinwiki.com/wiki/index.php?title=General#Basic_Sound_Troubleshooting Basic Sound Troubleshooting] section. 

==== Sound Board Interface Error ====

A "Sound Board Interface" error occurs when the MPU board can not communicate properly with the sound board at boot up. There could be several reasons for this problem.

#Ribbon connector not properly seated. The ribbon to the sound board(s) originates at J202 on the MPU board, goes to the FlipTronics board, then to the sound board (whether pre-DCS or DCS), then on to the DMD controller board.
#Failed ribbon cable. Due to over-flexing, the ribbon may have failed.
#Mismatched ROMs between the MPU and sound board. This isn't as big of an issue as with Data East games, but updating the game ROM to a newer version while leaving the sound ROMs at an older, even prototype version, could cause this problem.
#Solder bridges, or corrosion under the ribbon connector.
#Failed I/O buffer ICs on either the sound board or on the MPU board

On '''DCS sound boards''', U18 buffers data '''from''' the MPU. U19 buffers data '''to''' the MPU. Testing these ICs using the [http://www.pinwiki.com/wiki/index.php?title=General#Testing_an_integrated_circuit this method] should yield similar results to the values listed below. Note that this test method can't identify either a good or a bad integrated circuit with 100% certainty but using this test is preferable to removing chips unnecessarily. These readings were taken using a Fluke 179 DMM. Different meters, different manufacturers chips, and even individual variation in manufacture will probably cause your readings to be slightly different, yet consistently different. i.e. If the table shows .657 and your meter yields .630, then every pin listed at .657 should read close to .630 with your meter.

Probe pin 10 with the DMM red lead. Probe each of the other pins with the black lead.

{| class="wikitable"
! Pin 
! Diode Test Value U18 
! Diode Test Value U19 

|-
| <center> 1 </center> || <center>.583</center> || <center>.580</center>
|-
| <center> 2 </center> || <center>.519</center> || <center>.659</center>
|-
| <center> 3 </center> || <center>.657</center> || <center>.510</center>
|-
| <center> 4 </center> || <center>.657</center> || <center>.516</center>
|-
| <center> 5 </center> || <center>.511</center> || <center>.656</center>
|-
| <center> 6 </center> || <center>.511</center> || <center>.656</center>
|-
| <center> 7 </center> || <center>.657</center> || <center>.510</center>
|-
| <center> 8 </center> || <center>.657</center> || <center>.510</center>
|-
| <center> 9 </center> || <center>.511</center> || <center>.656</center>
|-
| <center> 10 </center> || <center>Red Lead</center> || <center>Red Lead</center>
|-
| <center> 11 </center> || <center>.580</center> || <center>.580</center>
|-
| <center> 12 </center> || <center>.510</center> || <center>.657</center>
|-
| <center> 13 </center> || <center>.657</center> || <center>.518</center>
|-
| <center> 14 </center> || <center>.657</center> || <center>.516</center>
|-
| <center> 15 </center> || <center>.519</center> || <center>.656</center>
|-
| <center> 16 </center> || <center>.517</center> || <center>.578</center>
|-
| <center> 17 </center> || <center>.657</center> || <center>.517</center>
|-
| <center> 18 </center> || <center>.578</center> || <center>.509</center>
|-
| <center> 19 </center> || <center>.517</center> || <center>.657</center>
|-
| <center> 20 </center> || <center>.398</center> || <center>.398</center>
|}

[[File:WPCSoundBoardInterfaceErrorCorrosion.jpg|200px|thumb|left|Corrosion in the area of a critical signal caused a "Sound Board Interface Error".]] 
The root cause of a "Sound Board Interface Error" on a Star Trek:The Next Generation game is shown at left. The corrosion on the trace leading to pin 28, created a conductive bridge to pin 29, which is a critical signal to the sound board (WDEN).
 

[[File:WPCpreDCSSoundBoardSolderBridgeatU16.jpg|200px|thumb|left|A solder bridge at the circled location (U16), connecting pin 7 of the IC (ground) to the via and hence connecting pin 2 to ground, manifested as a "Sound Board Interface Error".]] 
Another physical PCB problem pictured at left (but repaired), caused a "Sound Board Interface Error". The sounds on this board operated fine since the error was in the hardware that talks back to the MPU.

A similar problem can be the cut component lead just left above the yellow circle. If it is bend towards the printed trace and making contact, it can also manifest itself as the "Sound Board Interface Error".
 

==== Shorting the Speaker Leads or a Shorted Speaker ====

[[File:BlownTDA2030.jpg‎|200px|thumb|left|Clearly, a major malfunction.]] 
A blown sound amp will cause a loud buzz when the game is powered on. Generally, amps blow due to reduced impedance (aka resistance, ohms) in the speaker(s). If a speaker shorts, the associated amp(s) will blow. Or, if the drive connection (not ground) to a speaker breaks free of the speaker connection lug and touches ground with the power on, the associated amp(s) will blow. Note that the speaker metal housing is connected to ground.

The image at left shows two amps from the same WPC-95 AV board that were blown when the non-ground speaker wire broke free and touched the speaker housing. It is good practice to solder the speaker wires onto the speaker connection lugs to prevent this from every happening.

Diode testing is an effective method of determining that an amp is blown. Place the red lead of your DMM on the center leg of the amp and test each of the remaining four legs. Compare results to a known good amp of the same type. Generally, readings between .5 and .8 should be observed.

==== Lowering the Minimum Volume ====
By default the game volume can be set no lower than '8' to prevent an operator from setting the volume too low. This can be overridden by entering the adjustments menu and setting Adjustment 1.28 (Minimum Volume Override) to yes. You can now set the volume as low as you like.

====High Frequency Sound Only====
This applies to pre-DCS and DCS sound boards. Uncertain if AV boards apply or not.

There is a situation where only the tweeter / high frequency sound can only be heard. This will result in the game sounding much quieter than usual. Most speaker systems are parallel circuits. However, the woofer on a pre-DCS sound system is in series with the midrange speaker. The high frequency speaker is in a parallel circuit to the mid and low range speakers. If there is no sound from the woofer in the bottom of the cabinet, there will be no midrange from the speaker panel.

First, make certain that the speaker output wiring from the sound board is connected correctly. Also, there is a bullet connection located inline which must be connected. This bullet connections ties the low and midrange speakers in series. Finally, check the connections at the woofer in the bottom of the cabinet to make certain the female spade connectors are secured to the speaker terminals. If all connections are secure, there is a chance that the woofer speaker is blown.

====Pre-DCS Sound Board Issues====

The blue Philips 47µF 35v axial electrolytic capacitors on these sound boards are prone to failure, often testing with no capacitance or extremely high equivalent series resistance.

===== Power on Sound Tones (Bongs) =====

After a successful boot, the game should make a single "bong" sound. The game provides a sound board problem indication with the following number of bongs.

Pre-DCS Sound Board Games.
*1 - No issues...enjoy a game.
*2 - U9 RAM failure.
*3 - U18 ROM failure.
*4 - U15 ROM failure.
*5 - U14 ROM failure.

=====No Sound at all=====
The highest probability reason for the complete lack of sound is connections to the speakers. The IDC connectors at J504 and J505 carry the sound to all speakers in the game. Since the speakers are connected in series on a pre-DCS game, any break in the speaker signal loop will cause loss of all sound. First check the small gauge wires at connectors J504 and J505. Since they are IDC connectors, they are prone to breaking free from the connector. Next ensure that all speaker connections are solid.

It is possible for a speaker to fail, commonly called "blown". You can test a speaker by applying anything from an AA battery to a 9V battery to the speaker terminals. You should see the speaker cone react when the battery is touched to the terminals.

=====Unbalanced Sound=====
Pre-DCS sound boards are not 100% interchangeable across games. Games from Funhouse to Party Zone (including Funhouse, Harley Davidson, Bride of Pinbot, Slugfest, Gilligan's Island, Terminator 2, Hurricane, and Party Zone) use different resistor values at R23/R24 than the remaining games that used the pre-DCS sound board (games from Hot Shots basketball through The Addams Family Gold). If you find the sound "unbalanced" between background sounds and voices, for instance, check the following resistor values.

R23/R24 values for... 
::Funhouse through Party Zone - 150K ohms 
::Hot Shots through TAFG - 56K ohms 

Note that the resistor value indicated in the schematics for pre-DCS sound boards at R22 and R25 are wrong. The schematics indicate 150K ohms. The correct value is 120K ohms.

=====No Sound or Low Volume Sound from Right Speaker=====
[[Image:WPCSpeakerAndCap.jpg|300px|thumb|left|The 10uf non-polarized capacitor on the "Tweeter" (right) speaker of a pre-DCS game (Twilight Zone).]] 
As Joe "Tony" Dziedzic discusses [http://www.dziedzic.us/wpc_speaker_sound_info.html here], "the back box speakers are wired in parallel, with a 10uf non-polarized capacitor in series with the right speaker (the tweeter). The capacitor is used to block lower frequency sounds from being reproduced by the speaker. Technically, the capacitor forms a first-order high-pass filter with a crossover frequency of 4000 Hertz. This configuration presents an effective impedance of around 4 ohms."

If the 10uf capacitor fails "open", then the signal to the speaker is open and the speaker will remain silent.

The repair is simple...replace the capacitor.
 

=====Distorted or slightly "off" sounds=====
[[Image:PreDCSSoundBoardC38NotStuffed.jpg|300px|thumb|left|C38 is not stuffed on some pre-DCS sound boards.]] 
The pre-DCS sound board uses 47µF capacitors as filters in the sound circuit; C15, C36, and C38. If one or more of these caps fail, certain sounds may not be as loud or as clear as intended. The game will just sound "off" with perhaps slightly unbalanced sounds. An amazingly high percentage of these caps fail. It is recommended that if your sounds are a bit "off" that you replace all of these caps.

'''Note:''' as shown at left, C38 is sometimes not stuffed at the factory. It appears that audio channel 1 and channel 2 (in C38s path) from the Yamaha YM3012 are redundant, making this cap unnecessary.
 

[[Image:preDCSSoundBoardCapComparison.jpg|300px|thumb|left|C49, implemented in two different ways on the pre-DCS sound board.]] 
Also, some pre-DCS sound boards looked to have been "hacked" to add a ceramic capacitor just below the clock crystal X1. This is not in fact a hack. It appears to "fix" the omission of C49 on some versions of the PCB. C49 is located at the edge of the board, just above the crystal.
 

=====Popping, Scratchy Sound, Very Hot LM1875 Heat Sink, or Shorted Speakers=====
Sometimes, the tantalum/ceramic caps in the amp circuit fail too. This can result in too much AC "ripple" feeding the amp as well as DC output to the speakers, which they do not like. The following components are all suspect...

*C20 (10µF, 20V tantalum)
*C46 and C47 (both 1µF, 35V tantalum)
*C22 (22µF, 35v electrolytic)
*C23 (.22µF, 10V, ceramic)

Normally, the positive side of the tantalum cap at C26 will measure about 50mv of AC referenced to game ground. Anything more indicates a problem with these tantalum caps. You will also be able to measure DC voltage across the speaker outputs. There should normally be no DC voltage across the speaker outputs.

The LM1875 may also run very hot. Normally, you can grasp the heat sink without burning your hand. It will be hot, but not so hot that you can not squeeze it or grasp it very long. '''Note:''' this assumes that the volume is set to about 8. Setting the volume to 18 will require the heat sink to dissipate more heat. The heat sink will be too hot to grasp (for very long). If at "normal" volume levels and the heat sink is so hot that you can not grip it, failing tantalum caps should be suspected. If after replacing the tantalum caps the popping and scratchiness persist, the LM1875 amp may have been damaged.

=====Volume Not Adjustable and/or Stuck at Low Volume=====
This problem manifests as a very low volume from the speakers, equivalent to the lowest sound level setting. The volume setting may be adjusted from the coin door, and the DMD volume "thermometer" will move normally, but the speaker volume will not change. While the cause of this issue could be a failed digital POT as discussed [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Volume_Suddenly_at_Maximum here], a failed MC3340 electronic attenuator may also be the cause. You may be able to identify the MC3340 as the problem by comparing "diode test" results with a known good MC3340.

In one such case, pins 7 and 8 of the device where shorted together, causing the symptoms described. The failed MC3340 may also have caused the amp to become very hot, but this has not been conclusively proven.

Take care to ensure the MC3340 is actually at fault as this obsolete part is pricey and hard to find.

=====Wrong sounds being played=====
Generally, this problem boils down to a communication problem between the MPU and the sound board. Possible failure points are:

*Ribbon cables
*Male header pins on both MPU and sound board
*74LS374 data buffer ICs on the sound board used to communicate between the MPU and the sound board.
*Rarely, a failed 6264 RAM can cause this. The RAM is "tested" by the MPU. Sometimes it will pass the test, yet fail in game play. Odd...I know.

=====Volume Suddenly at Maximum=====

If the volume suddenly jumps to full volume and control of the volume via the coin door buttons does not work, check C18, a 47µF 35v axial electrolytic capacitor. The blue Philips capacitors on these sound boards are prone to failure and can cause this issue if bad. If that does not solve the problem there is a good chance that the digital POT (volume control) on the sound board has failed. The part is located at U5 and is an X9503. The X9503 is obsolete but it's successor the X9C503 works fine here.

=====Blown 1uF or 10uF Tantalum Capacitor=====
[[Image:WPCpreDCSBlownTantalumCap.jpg|300px|thumb|left|C46 blew up and burned quite spectacularly on this pre-DCS sound board.]]
[[Image:Wpc_pre-dcs_cap-failure-c28.jpg|300px|thumb|right|C28 failed on this pre-DCS sound board.]] 
The pre-DCS sound board uses 1uf tantalum caps in the amp circuit. Sometimes, for no good reason than simply being old, one of these caps will explode and burst into flames at game power on. C46 on the board shown at left did just that. In the great majority of instances, simply replacing the cap returns the board to service. This "burning into flames" can also happen to the +12V and -12V section with C26 and C28.

When the 1uF tantalum at C27 or C29 shorts internaly, it will cause the +12V or -12V to disapear. The LM7812 (U4) or LM7912 (U3) will run very hot. The tantalum draws all the current. The LM7812 and LM7912 have a limit of 1 Amp. The voltage will drop to zero when this happens, leaving the amplifier without power.

Other tantalum caps have been documented to explosively fail, including C28 and C47.

A tantalum capacitor can be tested by desoldering one leg and using a DMM (in diode check) to check for a short. Simply replacing the tantalum will solve the problem.

A contributing factor to these explosive failures was that the voltage rating on the capacitors that were used was too close to the operating voltage running through them (undersized components were typically used as a cost saving measure). As a general rule of thumb, the operating voltage should be 50% of the voltage rating of the tantalum capacitors. So, for a 12V circuit, at least a 25V capacitor should be used; a 50V minimum rating would be better.

All the tantalum capacitors used on the pre-DCS sound board are below:
* C20,C21: 10uF axial tantalum capacitor (original rating was 10V; use at least 35v instead).
* C26,C27,C28,C29,C37,C46,C47,C48: 1uF axial tantalum capacitor (original rating was 35V; use at least 50v instead).

Note that the tapered end is the positive side and also has a "+" symbol near it (however, with a burnt part, this might be impossible to see). Since the board was not silkscreened with any indications of component polarity, make note of the direction on the original part before removing it.

[[Image:Wpc_pre-dcs_tantalum-cap-polarity.jpg|250px|thumb|center|Diagram showing the tantalum capacitor locations and polarity]] 

After replacing one blown tantalum capacitor, it is possible that a second power up might blow a different one. Therefore, it might be a good idea to preemptively replace all the tantalum capacitors, especially if one has already experienced an explosive failure.
 

[[File:Failed1ufTantalumCap.jpg|300px|thumb|left|Another failed 1uf tantalum capacitor.]]
[[File:ReplacementCapForTantalum.jpg |300px|thumb|right|The replacement 1uf electrolytic capacitor installed, with the lead insulated to prevent the unlikely short to the heat sink.]] 
The tantalum caps on this board can be replaced with the same rated (1uf) electrolytic caps. The two caps adjacent to the large heat sink need to be positioned to allow space for the large 4700uf caps also adjacent to the large heat sink.
 

=====Sound Is Very Faint Even at Maximum Volume (CVSD Failure)=====
[[Image:55536-CVSD.jpg|300px|thumb|right|Two hard to find 55536 CVSD ICs.]] 
While most techs would suspect either a TL082 or a TL084 amplifier (on a pre-DCS sound board) or a 1458 amplifier (on a System 11 MPU) as the cause of this issue, the 55516/55532/55536/55564 CVSD (Continuously Variable Slope Delta-Modulator) can also cause this issue.

Isolation to the CVSD is pretty simple.

*Place the game into sound test.
*Use an oscilloscope to probe pins 9 and 12. A scope must be used since the signals are too subtle for a logic probe to detect.
*Pin 9 is a clock signal.
*Pin 12 is a data signal.

When the game is making sounds that use the CVSD (generally voice calls), both pin 9 and pin 12 should show "off nominal" signals. If the CVSD is working correctly, the output at pin 3 should be showing signal also. If pin 3 is not showing signal, then the CVSD has failed.
 

[[Image:CVSDReplacementFront.jpg|300px|thumb|left|A "daughter card" used to replace the 55536 CVSD (front).]]
[[Image:CVSDReplacementBack.jpg|300px|thumb|right|A "daughter card" used to replace the 55536 CVSD (rear).]]
During the run of the pre-DCS sound board, it is suspected that the 55536 CVSD part (and it's close cousins) was becoming hard/expensive to acquire. Williams created a "daughter card" to use in lieu of the CVSD. The daughter card used an MC3417 CVSD along with additional "tuning" resistors and capacitors. The sound quality result is indistinguishable from a 55536. Williams used a closed frame machine pin socket to accept the daughter card. The "chip notch" should be oriented just as you would the CVSD. That is, more of the card will be south of the chip socket than north of it.

While it might seem like a good idea to duplicate the design of this Williams card (part number 5768-14714-00) to replace the even harder to find 55536, the main part used, the MC3417, is equally hard to find today.

[[File:YT.png]] Jeri Ellsworth reverse engineered the 55564 (55536 equivalent) and posted [https://www.youtube.com/watch?v=2FRGwuxFDE4 this video] in October, 2011. She makes it seem "intuitively obvious to even the most casual observer"...

====DCS Sound Board Issues====

The DCS sound board was used in 18 games including:

*Indiana Jones: the Pinball Adventure
*Judge Dredd
*Star Trek: The Next Generation
*Demolition Man
*Popeye Saves the Earth
*World Cup Soccer
*The Pinball Circus
*The Flintstones
*Corvette
*Red & Ted's Road Show
*The Shadow
*Dirty Harry
*Theatre of Magic
*No Fear: Dangerous Sports
*Indianapolis 500
*Johnny Mnemonic
*WHO Dunnit
*Jack*Bot

===== Power on Sound Tones (Bongs) =====

After a successful boot, the game should make a single "bong" sound. The game provides a sound board problem indication with the following number of bongs.

DCS Sound Board Games.
*1 - No issues...enjoy a game.
*2 - U2 ROM failure.
*3 - U3 ROM failure.
*4 - U4 ROM failure.
*5 - U5 ROM failure.
*6 - U6 ROM failure.
*7 - U7 ROM failure.
*8 - U8 ROM failure.
*9 - U9 ROM failure.
*10 - U10-U12 RAM error. Not always identified from the main CPU board program. DCS sound board RAM failures are indicated by a message on the display, "U10-U12 RAM error".

=====Very Loud Humming at Power On=====
The DCS sound board uses two 10,000µF caps at location C20 and C21 to smooth rectified AC power. The negative side of C21 and the positive side of C20 are connected to analog ground at header J4, pins 6 and 7. This connection is fragile. If the game hums really loudly, immediately at power on, test for continuity between these points as shown in the pictures below. Often this loud hum is diagnosed as a failing cap when the real problem is simply a fractured trace. If the caps have been replaced previously, there is a good chance that the PCB through holes have been damaged.

<center>
<gallery widths=300px heights=300px perrow=3 caption="DCS Sound Board Filter Capacitor Connections. Continuity is shown as a zero ohm connection.">
File:DCSCapThroughHoleBungled.jpg|<center>The remains of through holes heinously ripped from a DCS sound board PCB. These "brown donuts" are still attached to the 10,000uf filter capacitor.</center>
File:DCSCapConnection1.jpg|<center>The first of two tests ensuring continuity between the filter capacitors and analog ground.</center>
File:DCSCapConnection2.jpg|<center>The second of two tests ensuring continuity between the filter capacitors and analog ground.</center>
</gallery>
</center>
 

=====U10-12 RAM ERROR=====
[[File:WPC95U10U12Message.jpg|300px|thumb|left|A DCS game boot time RAM error message, accompanied by 10 very annoying bongs.]]
Replacement RAM ICs for the DCS sound board are becoming harder to find. The board uses three, 2Kb skinny dip 6116 cache rams with an access time of 35nS or better. These are obsolete and long gone. The good news is that the board has jumpers for 6264 type 8Kb cache rams. Jumper W4 is installed for 2Kb rams. Jumper W4 should be removed and jumper W5 installed to use 8Kb rams. All RAM ICs need to be replaced at the same time for this configuration to work.

A relatively inexpensive, and still in production replacement, is the IDT 7164S20TPG.

RAM testers are not able to detect chips that do not meet the speed requirement. While slower RAM may pass chip test, it may fail on the board and cause the "10 bongs" error indication. 

===== Muffled Sound and Speech/No Sound =====
[[File:DCSSoundBoardCaps.jpg|300px|thumb|left|C32 and C41, both electrolytic caps, are in series in the sound amplification circuit of the DCS sound board.]] 
Muffled audio can be caused by failure of the two 1uf/63V electrolytic capacitors that are in the audio circuit for each amplifier. Simply replacing them may clean up the audio. A typical 1uf/50V axial electrolytic capacitor will work fine.
 
It is also possible for one or both of these capacitors to fail completely open. In that case, no sound at all will come out of that capacitor's channel since they are in series with amplifier (C32 for the cabinet speaker and C41 for the backbox speakers.) Replacing the appropriate capacitor can restore sound to the silenced channel.
 

===== Scratchy Audio or mumbled speech =====

[[File:DCSSoundBoardCeramicCaps.jpg|300px|thumb|left|C37 and C45, both ceramic caps, sometimes cause scratchy audio.]] 
During production of WPC-95 games, Williams removed two small ceramic caps (C47 and C51) from the A/V board to clean up the sound. This update should also be applied to the DCS sound board. On the DCS board C37 and C45 are the equivalent caps to be removed. Simply clip the caps from the board. You do not need to desolder them. This cleans up the sound and speech on some games like Demo Man quite well.
 

====WPC-95 A/V Board Sound Issues====

The WPC-95 A/V Board was introduced, along with the WPC-95 system, with Congo and was used through the end of the WPC game system run. WPC-95 games using the A/B Board are listed below. The sound ROM part number is shown in parenthesis.

*Congo (5343-50050)
*Attack from Mars (5343-50041)
*Safe Cracker (5343-90003)
*Ticket Tac Toe (not a pinball)
*Tales of the Arabian Nights (5343-50047)
*Scared Stiff (5341-15191)
*Junk Yard (5341-15403)
*NBA Fastbreak (5341-15418)
*Medieval Madness (5341-15451)
*Cirqus Voltaire (5341-15584)
*No Good Gofers (5341-15591)
*The Champion Pub (5341-15703)
*Monster Bash (5341-15931)
*Cactus Canyon (5341-15191)

Always check the speaker connections to the A/V board (J504 and J505) and the wiring at the speakers before assuming there is a problem with the board. The speakers themselves can go bad; you can do a quick "click test" with a D-cell battery and a set of jumper leads to rule out dead speakers. Disconnect the speaker connections at the A/V board and connect your battery jumper leads to the pairs of wires in the J504 and J505 connectors; you should hear a click from the speaker if it is good. If you don't hear the click try the connection at the speaker itself to rule out wiring issues.

The analog output of the A/V board feeds into a TLO84 op-amp (U1) that is configured as a pair of low-pass and high-pass filters; these are used to separate the low-frequency sounds (destined for the cabinet speaker) and the high-frequency sounds (destined for the back box speakers). These two channels - signified on the schematic as AUDIO_R (cabinet) and AUDIO_L (back box) feed into a pair of TDA2030AV amplifiers; U5 drives the back box speakers and U6 drives the cabinet speaker.

The outputs of U1B and U1C (pins 7 & 8) can be briefly connected with a jumper lead to help narrow down issues when one of the two channels is not working or has weak/distorted output. When the two pins are jumpered you should be able to hear approximately the same level of sound from the cabinet and back box speakers. (Use the T.7 diagnostic test to play sound clips for the game during your testing.)

===== On Board Voltage Regulation =====
The WPC-95 A/V Board "digital" side is powered by the same 5VDC that is regulated by the power/driver board. The "analog" side of the A/V board, specifically the two TL084s and the AD1851 D-to-A converter, all use +5VDC and -5VDC that is regulated by the 78L05 and 79L05 respectively. Four rectifying diodes provide about +/- 17VDC to these regulators. If the sound is low or scratchy, check these two voltages first. Both +5VDC and -5VDC can be easily measured at pins 4 and 11 of either TL084.

===== Power on Sound Tones (Bongs) =====

After a successful boot, the game should make a single "bong" sound. The game provides a sound board problem indication with the following number of bongs. Note that if more than one sound ROM exhibits a checksum error, only the first failed ROM will be indicated. Once that failed ROM is replaced, the next failed ROM will be indicated upon subsequent boots.

[[File:SoundROMChecksumError.jpg|300px|thumb|Right|WPC-95 boot time Sound Board ROM error message, accompanied by three bongs.]]

Audio/Video Board Games (WPC-95).
*1 - No issues...enjoy a game.
*2 - S2 ROM failure. Note: Two bongs also occur if jumper W3 is IN on the MPU board, and the installed RAM size is 6264. If an NVRAM was just installed, check this jumper. See the section on [[Williams_WPC#Jumpers.2C_RAM_and_ROM_size | jumpers]].
*3 - S3 ROM failure.
*4 - S4 ROM failure.
*5 - S5 ROM failure.
*6 - S6 ROM failure.
*7 - S7 ROM failure.
*10 - U9, U10, or U11 RAM failure (see below)

[[File:WPC95U9-U11Error.jpg|300px|thumb|left|WPC-95 boot time RAM error message, accompanied by 10 very annoying bongs.]]
[[File:WPC95U10U12Message.jpg|300px|thumb|right|WPC-95 boot time RAM error message, accompanied by 10 very annoying bongs.]] 
A/V sound board RAM failures are indicated by a message on the display, either "U9-U11 RAM error" or "U10-U12 RAM error". This is apparently game software dependent. A/V RAM are, in fact, U9-U11. Apparently, this message wasn't updated in some of the software with the introduction of the A/V board. 

===== Loss of One Channel =====

[[File:WPC95AVBoardSoundIssue.jpg|300px|thumb|left|C38 and C39, which can cause loss of a single channel]] 

If one channel is out or weak/distorted try the jumper at U1 pins 7 & 8 noted above. If no change is detected in the sound output it is likely the associated TDA2030AV amplifier (U5 or U6) has failed. Before replacing the amplifier jumper a 1 MFD 63 volt capacitor across C38 and C39 in turn (observe polarity!) to rule out a defective coupling capacitor. If jumpering pins 7 & 8 of U1 significantly improves the sound levels it is likely that U1 itself has failed.
 

===== Scratchy Audio =====

[[File:AVBoardCapsRemoved.jpg|300px|thumb|left|A later production Williams WPC-95 AV Board, with C47 and C51 intentionally unstuffed at the factory]] 
Williams removed two small ceramic caps (C47, C51, pictured at left) later in the production run of AV boards. If your game's audio is just a bit scratchy, and these caps have not been removed, you may be able to improve audio quality by removing them. Simply clip both sides of the cap. There is no real need to desolder them.

 

===== Really Loud buzzing sound for a second or two =====

If your game sometimes produces a really loud buzzing sound at random, check the version of your S2 sound rom. This problem was fixed with the latest S2 sound ROM for Attack from Mars, Congo, Safe Cracker and Tales of the Arabian Nights. Scared Stiff might also be affected but no version history for sound 1.1 exists for this game. Later games are not affected.
 

===Flipper Problems===

In most instances, an inexperienced tech will immediately blame the flipper coil itself for weak or non-functioning flippers. It is logical to blame the coil for the source of the problem. The flipper coil is, after all, the end reason why a flipper becomes engaged. However, its failure is the least probable reason that a flipper is not working. 

====Flipper does not work====
In this case, you've started a game, you press the flipper cabinet switch, and nothing happens.

The first thing to do is inspect the wire connections to the flipper coil lugs. The most common reason a WPC flipper does not function is that either one of the wires broke from the game to the lug, or one of the coil winding wires, has broken away from the coil lug and is no longer connected to the coil. This is a pretty simple fix. Make a clean cut to the wire, strip or sand 1/4" to 3/8" of insulation back, and make a nice solder joint on the coil.

[[Image:WPC95FlipperSpadeConnectors.jpg|300px|thumb|left|A good reason to nip spade connectors off and solder directly to the coil lug. This spade connector simply fell off the coil lug. Luckily, it didn't come to rest on an adjacent lug.]] 
Some WPC-95 titles used "spade connectors" (also known as FASTON connectors) to attach wires to the coil lugs. This was done for ease of manufacture and for that reason only. Similar to a wire breaking free, these spade connectors sometimes do not provide a solid connection and sometimes simply fall off. In that case, cut the spade connector off and solder the wire directly to the coil lug. This makes a much better connection that is also much more reliable. Should a spade connector fall onto an adjacent coil lug, it's very possible that a short circuit will be created, possibly damaging the FlipTronics board. 

=====Mechanical Reasons=====
There are a couple of mechanical reasons a flipper may not be working, including:
*Broken flipper link
*Flipper crank not "biting" flipper shaft (this would most likely manifest as a flipper that continues to move backwards, out of adjustment)

Simple inspection of the flipper mechanism should guide your corrective actions.

=====Pre-FlipTronics Games Electrical Reasons=====
*Failed flipper power supply - make sure that DC flipper power is present at the coil using your DMM. Place the red lead on a coil lug, the black lead on game ground (siderail or ground braid anywhere in the game). You should read about 70VDC.
*Flipper cabinet switch not "making" or fouled so badly that it doesn't conduct flipper power
*Fouled or missing flipper end-of-stroke switch. Pre-FlipTronics games relied on EOS switches in the same way that older games do. That is, power is routed to the power stroke winding of the coil via the EOS switch. If the EOS switch is fouled, only the hold winding will receive power; perhaps inadequate to move the flipper at all.

=====FlipTronics Games Electrical Reasons=====
*Failed flipper power supply. Flipper power originates at the transformer. It is routed through the power/driver board (which does nothing to it) and then to the FlipTronics board. The FlipTronics board rectifies the AC power via an onboard bridge rectifier. Power may be interrupted anywhere along this path, including a failed bridge rectifier or blown fuse.
*Failed flipper coil "power stroke" winding
*Flipper cabinet switch not "making" or flipper opto board not working
*Damaged connection between flipper cabinet switch and FlipTronics board
*FlipTronics board not recognizing flipper cabinet button switch closure
[[File:MissingPinFlipTronics.jpg|300px|thumb|left|A missing pin in the FlipTonics-to-MPU interface. The missing pin prevented transmission of the F8 signal (D7), which is the upper left flipper switch closed signal.]] 
An unusual reason for the flipper switch closure signal not being sent to the MPU is shown at left. 
*Failed logic path on the FlipTronics board including the transistors. See: [[Williams_WPC#WPC_FlipTronics_I_.26_II_Boards| WPC FlipTronics I and II Boards]] for a description of the signal path.
*Improperly seated or failed ribbon connectors between MPU and FlipTronics board

====Flipper is weak====
In this case, the flipper makes a stroke, but it's a weak stroke, not striking the ball with normal force.

=====Mechanical Reasons=====
*Not enough vertical movement in flipper bat (crank tightened too close to bushing)
*Cracked, broken or egged flipper bushing
*Mushroomed coil stop and plunger (replace coil sleeve too)
*Missing link bushing or oval link "eyelet"
*Tired flipper crank (will not tighten on bat shaft)

[[File:WPC Flipper Link Plunger.JPG|thumb|left|300px|An Example of an Egged Flipper Link and Mushroomed Flipper Plunger - Lower Link and Plunger Shown in Picture is new]]
 

=====Pre-FlipTronics Games Electrical Reasons=====
*Flipper cabinet switch not "making" or fouled so badly that it does not conduct
*Failed flipper end-of-stroke switch

=====FlipTronics Games Electrical Reasons=====

*Dirty flipper cabinet switch optos
*Power stroke winding of coil failed

====Flipper locks on or fails to fall to resting position====
In this case, the flipper locks in the up position, either at game power on or when the flipper cabinet switch is pressed.

=====Mechanical Reasons=====

=====Pre-FlipTronics Games Electrical Reasons=====

=====FlipTronics Games Electrical Reasons=====
*Flipper cabinet switch opto interupter not returning to proper at rest position
*Sticky flipper buttons, which can lead to opto interupter not returning to at rest position.

=====Fodder (may be useful to complete this section)=====
*Fouled or broken "normally closed" EOS switch
*Fouled or broken flipper cabinet switch
*Flipper relay not enabled
*Fouled / dirty or non-functioning flipper opto switches
*Upper flipper switch closures in switch test, when there aren't any upper flippers on game

==Parts Substitutions & Replacements==
===Boards===
====MPU====
* "Ewe 22" Security PIC chip replacement for WPC-S/WPC-95: http://www.shiftedbit.com/products.htm

==Repair Logs and Game Specific Problems and Fixes==
Since WPC games are overwhelmingly the most popular pinball titles at the moment, and there are a vast amount of titles with so many game specific issues, please refer to the [http://pinwiki.com/wiki/index.php?title=Williams_WPC#Game_List Game List] section of this guide. Click on the specific game, and a new page will open regarding repair logs and game specific problems and fixes for that particular game title.
 

=== World Cup Soccer locks on Right Sling and both Left and Right Kickout Holes at Power On ===
[[Image:WPCDriverBoardKeying.jpg|400px|thumb|left|Board layout diagram showing identical connector and keying at J124, J128, and J132)]] 
[[Image:WPCJ124J128Keying.jpg|400px|thumb|left|Image showing identical connector and keying at J124, J128, and J132)]] 
<ul>Problem</ul>
Upon power on, and with the coin door closed (defeating the high voltage interlock switch), the right slingshot as well as the left and right saucer kickout hole coils lock on.

<ul>Cause</ul>
The flash lamp drive connector that should be connected to J124 is instead connected to J128.

<ul>Discussion</ul>
Connecting the female plug to the wrong header pins is entirely possible since the connectors are the same width and are keyed identically. In World Cup Soccer (at least), the wire bundle is long enough to be connected (properly) to J124 or (improperly) to J128 or J132.
 

===S2 Sound ROM Failure on WPC-95 After a Successful Boot===
If game is turned on and has a successful boot, but after a few minutes, the game bongs twice indicating an S2 sound ROM failure and becomes unresponsive, try reseating the ASIC chip on the MPU. Make sure to use the proper removal tool, rather than a screwdriver--an improper tool will damage the chip.