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Data East/Sega

2026-06-06T17:29:02Z

Diz: /* Data East CPU Board LED Flash Sequence at Boot Up When Working Properly - Potential CPU failure*/

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

==Introduction==
[[Stern_Pinball | Data East/Sega pinball]] used a board set with minor differences from 1987 to 1995. This boardset, like most hardware of this generation, is very derivative of [[Williams_System_9_-_11| Bally/Williams System 11 hardware.]]

[[File:De boardset.jpg‎|400px|thumb|left|Data East Standard DMD Board Set, this from a Star Wars]]
The following boards are typical of what you will find in a Data East backbox.
*RED - Power Supply
*BLUE - CPU
*YELLOW - Playfield Power Board
*GREEN - Sound Board

The first two games, Laser War and Secret Service, did not use a PPB board, and were equipped with a flipper power supply (very similar to the Williams System 7, 9, & early 11 flipper power supply). Secret Service used an MRB-1 (Mega Resistor Board) which was mounted to the back of the body of the cabinet. 
There can also be two additional boards, not including satellite boards which were used such as a shaker motor driver board, a magnet control board, etc.
*Games with solid state flippers will have a flipper control board name the TY-FFASI board. This board is located on the left side of the lower cabinet. Games which have more than three flippers, Baywatch and others, use two flipper control boards.
*Display controller boards are mounted behind the displays. DMD controller boards have a separate CPU and communicate to the main CPU via a ribbon cable.
 

==Games==

For an extensive list of games produced by Data East and Sega, see the [[List of Data East Games]].

The following table lists regular production games based on their circuit board (PCB) and system generations.

Clicking on the individual game name will open a new page dedicated to that particular game. Several of the games have their own coil assignment chart list on their page.

{| class="wikitable"
!colspan="9" |Game List and Board Version
|-
!Game (Manufacture Date)
!CPU
!Power Supply
!MRB/PPB
!Display
!Sound
!Flipper
!Transformer
!Notes

|-
|[[Laser_War |Laser War (3/87)]]
|DE-0262-2 or 520-5003-00 or 520-5003-01
|520-5000-00
|SMIG Board
|(1x) Master:520-5004-00 (2x) 7 Digit A/N:520-5005-00 (2x) 7 Digit N:520-5006-00 (1x) 4 Digit N:520-5007-00
|DE-0288-1A
|No PCB 3 lug coil and EOS switch. 520-5001-00 Flipper Power Supply
|010-5000-00
|

|-
|[[Secret_Service|Secret Service (2/88)]]
|520-5003-02
|520-5000-00
|MRB: 520-5015-00 
SMIG Board
|(2x) 7 Digit A/N 
(2x) 7 Digit Numeric: 520-5014-01 
|520-5002-01
|No PCB 3 lug coil and EOS switch. 520-5001-00 Flipper Power Supply.
|010-5002-00
|Start of four 7 digit A/N displays.

|-
|[[Torpedo_Alley|Torpedo Alley (8/88)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 7 Digit A/N 
(2x) 7 Digit Numeric: 520-5014-01 
|520-5002-01
|No PCB 3 lug coil and EOS switch. 520-5001-00 Flipper Power Supply.
|010-5002-00
|

|-
|[[Time_Machine|Time Machine (11/88)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 7 Digit A/N 
(2x) 7 Digit Numeric: 520-5014-01 
|520-5002-01
|No PCB 3 lug coil and EOS switch. 520-5001-00 Flipper Power Supply.
|010-5002-00
|

|-
|[[Playboy_35th_Anniversary|Playboy 35th Anniversary (5/89)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 7 Digit A/N 
(2x) 7 Digit Numeric: 520-5014-01 
|520-5002-01
|Deger flippers with 2 Lug flipper coil using a 1N4004 and 1N5404 diodes (except on 100 test games with 520-5033-00 SS flipper board).
|010-5002-00
|Start of single wound flipper coil with only 2 lugs.

|-
|[[Monday_Night_Football|ABC Monday Night Football (9/89)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 16 Digit A/N: 520-5030-00
|520-5002-02
|Deger flippers with 2 Lug flipper coil using a 1N4004 and 1N5404 diodes (except on 100 test games with 520-5033-00 SS flipper board).
|010-5002-00
|Start of two 16 digit A/N displays

|-
|[[Robocop|Robocop (01/90)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 16 Digit A/N: 520-5030-00
|520-5002-02
|520-5033-00 SS Flipper board 2 flippers with 2 Lug flipper coil and one 1N4004 diode
|010-5002-00
|First full game with solid state flippers

|-
|[[Phantom_of_the_Opera|Phantom of the Opera (4/90)]]
|520-5003-02
|520-5000-00
|PPB: 520-5021-00
|(2x) 16 Digit A/N: 520-5030-00
|520-5002-02
|520-5033-00
|010-5002-00
|

|-
|[[Back_to_the_Future|Back to the Future (6/90)]]
|520-5003-03
|520-5000-00
|PPB: 520-5021-00
|(2x) 16 Digit A/N: 520-5030-00
|520-5002-02
|520-5033-00
|010-5002-00
|First DE game to use a non-reflexive MPU board

|-
|[[The_Simpsons|The Simpsons (10/90)]]
|520-5003-03
|520-5000-00
|PPB: 520-5021-02
|(2x) 16 digit A/N: 520-5030-00
|520-5002-03
|520-5033-00
|010-5002-00
|

|-
|[[Checkpoint|Checkpoint (2/91)]]
|520-5003-03
|520-5047-00
|PPB: 520-5021-00
|128x16 DMD 520-5042-00
|520-5002-03
|520-5033-00
|010-5002-00
|First pinball machine with a DMD display

|-
|[[Teenage_Mutant_Ninja_Turtles|Teenage Mutant Ninja Turtles (6/91)]]
|520-5003-03
|520-5047-00
|PPB: 520-5021-00
|128x16 DMD 520-5042-00
|520-5002-03
|520-5033-00
|010-5003-00
|

|-
|[[Batman|Batman (8/91)]]
|520-5003-03
|520-5047-00
|PPB: 520-5021-00
|128x16 DMD 520-5042-00
|520-5050-01
|520-5033-00
|010-5003-00
|

|-
|[[Star_Trek_25th_Anniversary|Star Trek 25th Anniversary (9/91)]]
|520-5003-03
|520-5047-00
|PPB: 520-5021-00
|128x16 DMD 520-5042-00
|520-5050-01
|520-5033-00
|010-5003-00
|

|-
|[[Hook|Hook (5/92)]]
|520-5003-03
|520-5047-00
|PPB: 520-5021-00
|128x16 DMD 520-5042-00
|520-5050-01
|520-5033-00
|010-5003-00
|

|-
|[[Lethal_Weapon_3|Lethal Weapon 3 (8/92)]]
|520-5003-03
|520-5047-01
|PPB: 520-5021-00
|128x32 DMD 520-5052-00
|520-5050-01
|520-5033-00
|010-5003-00
|First DE usage of 128x32 display

|-
|[[Star_Wars|Star Wars (12/92)]]
|520-5003-03
|520-5047-01
|PPB: 520-5021-00
|128x32 DMD 520-5052-00
|520-5050-02
|520-5033-00
|010-5003-00
|

|-
|[[Rocky_&_Bullwinkle|Rocky & Bullwinkle (2/93)]]
|520-5003-03
|520-5047-01
|PPB: 520-5021-00
|128x32 DMD 520-5052-00
|520-5050-02
|3 flippers. 520-5033-03.
|010-5003-00
|Recommended replacement 520-5076-00 flipper board

|-
|[[Jurassic_Park|Jurassic Park (6/93)]]
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5050-02
|3 flippers. 520-5033-03
|010-5003-00
|Motor Control board mounted under playfield 
Uses a shaker motor 
Recommended replacement 520-5076-00 flipper board

|-
|[[Last_Action_Hero|Last Action Hero (10/93)]]
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5050-03
|520-5070-00
|010-5003-00
|Uses a 520-5068-00 magnet control board 
Uses a shaker motor 
Recommended replacement 520-5080-00 flipper board

|-
|[[Tales_from_the_Crypt|Tales from the Crypt (12/93)]]
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5050-03
|3 flippers. 520-5033-03
|010-5003-00
|Uses a shaker motor 
Recommended replacement 520-5076-00 flipper board

|-
|[[The_Who's_Tommy |The Who's Tommy (1/94)]]
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5077-00
|3 flippers. 520-5076-00
|010-5003-00
|Uses a servo motor board for the blinders 
Uses a shaker motor
|-
|WWF Royal Rumble (5/94)
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5077-00
|4 flippers. 520-5080-00 (2 used)
|010-5003-00
|Start of coil power interlock switch usage. 
Uses a shaker motor

|-
|Guns N' Roses (7/94)
|520-5003-03*
|520-5047-02
|PPB: 520-5021-05
|128x32 DMD 520-5052-00
|520-5077-00
|3 flippers. 520-5076-00
|010-5003-00
|Uses a 520-5068-00 magnet control board 
Optional shaker motor supported with latest software

|-
|Maverick (10/94)
|520-5003-03*
|520-5047-03
|PPB: 520-5021-05
|192x64 DMD 520-5075-00
|520-5050-03
|520-5076-00
|010-5008-00
|First usage of 'super' 192x64 DMD display

|-
|[[Mary_Shellys_Frankenstein | Mary Shelly's Frankenstein (1/95)]]
|520-5003-03*
|520-5047-03
|PPB: 520-5021-05
|192x64 DMD 520-5075-00
|520-5077-00
|3 flippers. 520-5076-00
|010-5008-00
|

|-
|Baywatch (2/95)
|520-5003-03*
|520-5047-03
|PPB: 520-5021-05
|192x64 DMD 520-5075-00
|520-5126-02
|4 flippers. 520-5080-00 (2 used)
|010-5008-00
|

|-
|Batman Forever (7/95)
|520-5003-03*
|520-5047-03
|PPB: 520-5021-05
|192x64 DMD 520-5075-00
|520-5126-02
|3 flippers. 520-5076-00
|010-5008-00
|
|-
|}

<nowiki>*</nowiki> Extra pins at CN3 for printer. See the [[Data_East/Sega#CPU|CPU section]] for more information.

==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.

The game manual includes detailed information such as:

*Lamp matrix mapping and location
*Switch matrix mapping and location
*Coil and flasher lamp mapping and location
*Game rules
*Unique playfield parts list including a rubber ring list and locator
*Game specific wiring connections, lamp, and coil diagrams
*Circuit board schematics
*CPU, display, and sound ROM locations
*Circuit board jumper settings
*CPU version compatibility amongst current and previous games
*Diagnostic and troubleshooting information
*Theory of operation of some specific boards

====Documentation Errors/Addendums====
* On the 520-5047-01 power supply schematic, Rev A has a labeling error for D10 & D11, noted in [[media:Sb38.pdf|Service Bulletin 38]]. This was corrected in schematic Rev B (published August 14, 1992).
* For Lethal Weapon 3, [[media:LW3Addendum.PDF|Manual Addendum]] had several part number updates and a revised flipper assembly diagram (published July 2, 1992).
* For Guns n' Roses, [[media:Data_East_1994_Guns_N_Roses_English_Manual_Addendum_and_Revised_Page_31.pdf|Manual Addendum No 2]] was released to add testing instructions for the magnet and laser kick, and add schematics for the magnet board (published July 18, 1994).
* For WWF Royal Rumble, the manual erroneously lists part # 500-5021-10 for the lockdown bar, but since WWF is a widebody game, it should instead be part # 500-5757-00.
* For Tales From The Crypt, in the list of rubber rings on page 37, it lists two 1-1/2" rubber rings, but in the diagram, it shows three used on the playfield.

===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
|-
|[[media:Sb88.pdf|Nr. 88]]
|1996-10-14
|All Games (General)
|Excerpt From Customer Fax
|Troubleshooting for when game settings do not save
|-
|[[media:Sb87.pdf|Nr. 87]]
|1996-09-04
|Laser War to The Simpsons
|FYI: Alphanumeric & 7-Segment Display Operation
|Alphanumeric display theory of operation; digit & segment identification
|-
|[[media:Sb85.pdf|Nr. 85]]
|1996-05-15
|Twister to Current
|New 2-Flipper Theory of Operation and Schematic
|
|-
|[[media:Sb83.pdf|Nr. 83]]
|1996-01-23
|Batman Forever
|Premature Failure of the New Style Flipper Pawl
|
|-
|[[media:Sb78.pdf|Nr. 78]]
|1995-10-02
|Laser War to Batman Forever
|A handy little CPU troubleshooting gimmick
|Digital logic troubleshooting with the CPU chip and scope
|-
|[[media:Sb77.pdf|Nr. 77]]
|1995-08-24
|Current Games
|"What is this pinball machine trying to tell me?"
|Explanation of new "Operator Alert" tech messages feature
|-
|[[media:Sb76.pdf|Nr. 76]]
|1995-08-23
|Checkpoint to Hook
|Testing Sm. Dot Matrix (128X16)...Display Glass
|Bench testing a 128x16 plasma DMD
|-
|[[media:Sb75.pdf|Nr. 75]]
|1995-08-22
|All Games
|CPU Board - Blanking Circuit Theory of Operation
|
|-
|[[media:Sb74.pdf|Nr. 74]]
|1995-04-28
|Baywatch
|Modification to Early Production Games
|Fix for issue where diagnostic menu icons immediately start scrolling without any user input
|-
|[[media:Sb73.pdf|Nr. 73]]
|1995-04-28
|Baywatch & Batman Forever
|New Portals Service Menu
|Overview of new software service menus.
|-
|[[media:Sb72.pdf|Nr. 72]]
|1995-02-17
|Mary Shelley's Frankenstein
|Creature: A Technical Overview
|Overview of the creature assembly
|-
|[[media:Sb71.pdf|Nr. 71]]
|1995-02-17
|Maverick
|Ball Trap
|Two ball trap issues & fixes
|-
|[[media:Sb70.pdf|Nr. 70]]
|1995-02-14
|Mary Shelley's Frankenstein
|Software Change Notice
|Version 1.03 CPU code and 1.03 display code must be installed as a matched set to ensure compatibility. This update should not be mixed with prior code updates.
|-
|[[media:Sb69.pdf|Nr. 69]]
|1995-02-14
|Maverick
|Software Change Notice
|Version 4.04 CPU code and 4.01 display code must be installed as a matched set to ensure compatibility. This update should not be mixed with prior code updates.
|-
|[[media:Sb68.pdf|Nr. 68]]
|1995-01-27
|Mary Shelley's Frankenstein (+ games hereafter)
|New Service Feature: Bi-Directional Aud/Adj/Diag.
|
|-
|[[media:Sb67.pdf|Nr. 67]]
|1995-01-19
|Maverick
|OPTO's A Techinical Overview
|
|-
|[[media:Sb66.pdf|Nr. 66]]
|1994-11-02
|The Who's Tommy
|New Ball Kicker Arm Assembly
|Shooter/Kicker arm assembly upgrade/replacement due to high failure rate
|-
|[[media:Sb65.pdf|Nr. 65]]
|1994-11-02
|Maverick to Baywatch
|F.Y.I. Maverick Display 64 X 192 Dot Matrix Intro
|192x64 DMD & EPROM compatibility
|-
|[[media:Sb64.pdf|Nr. 64]]
|1994-11-01
|Guns N' Roses
|Shooter Lane Ramp Mounting Modification
|Fix for multiple balls ending up in the shooter lane, and the auto-launch failing to clear them
|-
|[[media:Sb63.pdf|Nr. 63]]
|1994-10-04
|Guns N' Roses
|Auto Launch Failure
|Troubleshooting for multiple balls in the shooter lane, and the auto-launch failing to clear them. See Service bulletin 64 for fix.
|-
|[[media:Sb62.pdf|Nr. 62]]
|1994-08-22
|All Games (Gen.) & Laser War to Maverick
|Coil Designation with Part Numbers
|List of coil part numbers with (turn/gauge specs) used in Laser War through Maverick
|-
|[[media:Sb61.pdf|Nr. 61]]
|1994-08-03
|Wacky Gator (Redemption)
|Update Instruction
|Wacky Gator redemption game update kit for premature power supply, transistor, and lamp failures on games produced between 03-05-03 and 03-29-94
|-
|[[media:Sb60.pdf|Nr. 60]]
|1994-07-22
|Guns N' Roses (+ games hereafter)
|New Design: Cabinet Legs / Backbox Easy Access System
|
|-
|[[media:Sb59.pdf|Nr. 59]]
|1994-05-27
|The Who's Tommy
|Servo Motor Stripping Gears
|Blinder mech issues
|-
|[[media:Sb58.pdf|Nr. 58]]
|1994-04-15
|Multiple Games
|Solid State Flippers - Remains Energized
|Issue caused by cold solider joints
|-
|[[media:Sb57.pdf|Nr. 57]]
|1994-04-08
|Tales From the Crypt
|Solid State Flipper Board
|Issue with weak left flipper caused by wrong resistor value on flipper board
|-
|[[media:Sb56.pdf|Nr. 56]]
|1994-03-01
|Multiple Games
|Game Code Updates
|Announcement that all game code updates will be sent on floppy disks
|-
|[[media:Sb55.pdf|Nr. 55]]
|1994-02-28
|Multiple Games
|Game Resets
|Game resets as a result of 5V shorting to ground; add insulating material between area on sound board and backplane.
|-
|[[media:Sb54.pdf|Nr. 54]]
|1994-03-23
|Multiple Games
|Flipper / End of Stroke Failures
|Update kit for premature failure of EOS switch contacts
|-
|[[media:Sb53.pdf|Nr. 53]]
|1994-01-31
|Jurassic Park
|Common & Inherent Problems
|Coils firing at random, switch matrix issues, blown fuses; display indicates 6 balls missing; flipper does not energize; display blanks out for 15-30 seconds in game over mode
|-
|[[media:Sb52.pdf|Nr. 52]]
|1993-12-16
|Tales From the Crypt
|PPB - L/R Relay Failure
|On a small number games prior to serial number 101664, a 24v AC relay was installed on some PPB boards, instead of 24v DC relay.
|-
|[[media:Sb51.pdf|Nr. 51]]
|1994-01-17
|Tales From the Crypt
|Printer Interface Not Functional
|Incorrect DIP switch setting on DMD controller board causes Printer Interface error message
|-
|[[media:Sb50.pdf|Nr. 50]]
|1993-11-16
|Multiple Games
|Dot Matrix Display Glass - Theory of Operation
|
|-
|[[media:Sb49.pdf|Nr. 49]]
|1993-11-16
|Multiple Games
|Solid State Flipper - Theory of Operation
|
|-
|[[media:Sb48.pdf|Nr. 48]]
|1993-11-12
|Last Action Hero
|Lock Ball Assembly
|Early production/sample games experienced ball jams in 6 ball trough; replace compression spring to correct issue.
|-
|[[media:Sb47.pdf|Nr. 47]]
|1993-10-24
|Jurassic Park
|EPROM Rev. 5.10.
|Fix for DMD blacking out for 15-30 seconds
|-
|[[media:Sb46.pdf|Nr. 46]]
|1993-10-19
|Jurassic Park
|Flipper Return Springs
|Flippers wouldn't return to the rest position as a result of a broken return spring. See also Service Bulletin 44.
|-
|[[media:Sb45.pdf|Nr. 45]]
|1993-11-12
|Tales From the Crypt
|Captive Ball/Flat Rail Update
|On games prior to serial number 98741, slam tilt and switch issues surface when the captive ball hits the stand up target and shorts against a ball guide. Includes instructions to install mylar to act as an insulator.
|-
|[[media:Sb44.pdf|Nr. 44]]
|1993-06-17
|Jurassic Park
|Flipper Return Springs (Ltd. Dist. by Serial #)
|Issue with malformed return springs. See also Service Bulletin 46.
|-
|[[media:Sb43.pdf|Nr. 43]]
|1993-06-17
|Jurassic Park
|Failure of Switch #37 Center Scoop
|On games prior to serial number 87390, center scoop switch can fail to work, caused by broken diode. Replace diode and add silicone rubber for cushioning.
|-
|[[media:Sb42.pdf|Nr. 42]]
|1993-06-17
|Jurassic Park
|Left-Right Motor (Fails Prematurely)
|On games prior to serial number 87177, limit switches need to be adjusted for motor (note--referenced diagram is missing). Also fixed via code in version 5.00.
|-
|[[media:Sb41.pdf|Nr. 41]]
|1993-06-17
|Jurassic Park
|Up-Down Motor (Fails Prematurely)
|On games prior to serial number 87012, install a spring kit to help raise the dino assembly, and a spring loaded crank arm to prevent damage to the motor if the head is forced down manually.
|-
|[[media:Sb40.pdf|Nr. 40]]
|1993-06-17
|Jurassic Park
|Weak Kick on Dino Saucer Eject
|On games prior to serial number 87177, kicker assembly might not be aligned properly (note--referenced diagram is missing), or the wrong spring might be installed.
|-
|[[media:Sb39a.pdf|Nr. 39A]]
|1993-06-17
|Jurassic Park
|T-Rex Theory of Operation
|Theory of operation of T-Rex head, testing information, and troubleshooting information
|-
|[[media:Sb39.pdf|Nr. 39]]
|1993-06-17
|Jurassic Park
|ROM Rev. 5.00 for Early Jurassic Park Games
|Issues with T-Rex head grabbing the ball leading to possible damage to a coil. Suggested adjustment fix, and software fixes for the issue in version 5.00.
|-
|[[media:Sb38c.pdf|Nr. 38C]]
|1993-04-02
|Rocky & Bullwinkle & Friends
|Ball Draining (Orbit Shot)
|Fix for an orbit shot ball drain between the flippers
|-
|[[media:Sb38b.pdf|Nr. 38B]]
|1993-01-04
|Star Wars
|Display Controller EPROMS
|DMD controller jumper settings depending upon what EPROMs are used in 2 different versions of the board.
|-
|[[media:Sb38a.pdf|Nr. 38A]]
|1992-08-13
|Star Trek (and later)
|Stealth Coating Maint.
|Cleaning product advice for playfields with a new topcoat starting with Star Trek.
|-
|[[media:Sb38.pdf|Nr. 38]]
|1992-08-13
|Lethal Weapon 3
|Type Error on P.S.
|520-5047-01 power supply labeling error for D10 & D11 on Rev A schematic (corrected in Rev B schematic).
|-
|[[media:Sb37.pdf|Nr. 37]]
|1992-07-20
|Hook
|Erratic Play
|Erratic switch (and slam tilt) & solenoid behavior caused by shorted strobe line on left drop target bank.
|-
|[[media:Sb36a.pdf|Nr. 36A]]
|1992-07-06
|Lethal Weapon 3
|Possible High Voltage Failures on Power Supply Bd.
|On early Lethal Weapon 3 games, a bad batch of zener diodes was causing power supply failures; resistor added in order to reduce in-rush current. (note: referenced schematic is missing).
|-
|[[media:Sb36.pdf|Nr. 36]]
|1992-07-20
|Lethal Weapon 3
|Flipper Adjustment
|Flippers appear to be weak and are unable to make the ramp shots; make sure flipper bats are aligned with the inlane guides.
|-
|[[media:Sb35.pdf|Nr. 35]]
|1992-04-16
|Star Trek 25th Anniversary
|Game Program
|Various game issues/bugs fixed in version 2.00
|-
|[[media:Sb34.pdf|Nr. 34]]
|1992-02-06
|Star Trek 25th Anniversary
|Chase Light Update
|Chase lights intermittently fail, game blacks out momentarily, and blows F1 & F2; caused by shorting of lamp leads in the assembly.
|-
|[[media:Sb33.pdf|Nr. 33]]
|1991-12-18
|Star Trek 25th Anniversary
|Transporter FX Theory of Operation
|Backbox transporter effect theory of operation & troubleshooting
|-
|[[media:Sb32.pdf|Nr. 32]]
|1991-12-17
|Star Trek 25th Anniversary
|Ramp-Up Mechanism
|Issue where the up/down ramp doesn't always come back down.
|-
|[[media:Sb31.pdf|Nr. 31]]
|1991-12-06
|Star Trek 25th Anniversary
|Program Update
|Bug fixes in game code 1.17
|-
|[[media:Sb30.pdf|Nr. 30]]
|1991-09-19
|Batman
|Shooter Lane Update
|Issue with shooter lane switch getting stuck.
|-
|[[media:Sb29.pdf|Nr. 29]]
|1991-05-07
|Checkpoint / Teenage Mutant Ninja Turtles
|Wiring of Speaker
|Incorrect speaker wiring causes buzzing, popping, and distorted sound.
|-
|[[media:Sb28a.pdf|Nr. 28A]]
|1991-02-20
|Multiple Games (Checkpoint to Present)
|Modification to new P.S. Comp
|Modification instructions to make a newer power supply backwards compatible with older games.
|-
|[[media:Sb28.pdf|Nr. 28]]
|1991-02-20
|The Simpsons
|Cooling Tower Breakage
|Add a pair of washers to the cooling tower screw to better secure the tower and help prevent it from breaking.
|-
|[[media:Sb27.pdf|Nr. 27]]
|1990-10-23
|The Simpsons
|Ground Fault Problem
|On games with serial numbers 31788 to 32212, there is a problem with the power switch that may cause a short and a shock hazard.
|-
|[[media:Sb26a.pdf|Nr. 26A]]
|1990-09-05
|Back to the Future
|Program Error
|Workaround for power up game code bug prior to version 2.7
|-
|[[media:Sb26.pdf|Nr. 26]]
|1990-09-04
|Back to the Future
|Program Update
|Fix for power up game code bug in version 2.7
|-
|[[media:Sb25.pdf|Nr. 25]]
|1990-05-08
|Phantom of the Opera
|Solid State Update
|On games prior to serial number 27607, flipper board fixes for two flipper issues (weak flipper, and a held flipper comes down without releasing the flipper button)
|-
|[[media:Sb24.pdf|Nr. 24]]
|1990-03-22
|ABC Monday Night Football
|Weak Ball Trough
|Fix for ball not being ejected into shooter lane, or barely being ejected into shooter lane from ball trough.
|-
|[[media:Sb23.pdf|Nr. 23]]
|1990-06-29
|Robocop
|Solid State Update
|Flipper board fixes for flipper issues (weak flipper, double flip, or held flipper comes down without releasing the flipper button)
|-
|[[media:Sb22.pdf|Nr. 22]]
|1989-12-07
|ABC Monday Night Football
|Q54 Failure
|Q54 (Outhole kicker) fails. Fix for lug shorting on the coil stop bracket.
|-
|[[media:Sb21.pdf|Nr. 21]]
|1989-12-05
|ABC Monday Night Football
|Links on ABC Monday Night Football
|Green flipper mech links were breaking after several days of use due to faulty material manufacturing. The color of new links is now blue.
|-
|[[media:Sb20.pdf|Nr. 20]]
|1989-12-04
|All Games
|Solenoid Failure
|Pop bumper coil failures caused by stuck activation switch. On Monday Night Football games starting with serial number 17586, each pop bumper now has its own fuse. A new pop bumper design was introduced in the middle of producing Playboy.
|-
|[[media:Sb19.pdf|Nr. 19]]
|1989-08-31
|Slap Shot Hockey (Redemption)
|Slap Shot Updates
|
|-
|[[media:Sb18a.pdf|Nr. 18A]]
|1989-07-14
|Playboy 35th Anniversary
|Ball Catch
|On early sample games, fix for ball trap issue under center ramp
|-
|[[media:Sb18.pdf|Nr. 18]]
|1989-06-12
|Playboy 35th Anniversary
|Program Revision
|Game code A02-3 fixes timing issue of switches that have too long of a delay to activate a coil
|-
|[[media:Sb17.pdf|Nr. 17]]
|1989-05-26
|Playboy 35th Anniversary
|Bulletin & Replay Level
|Game adjustments to increase ball times and replay percentages.
|-
|[[media:Sb16a.pdf|Nr. 16A]]
|1989-01-05
|Time Machine
|High Score Settings
|New recommendation for high score replay levels in game settings.
|-
|[[media:Sb16.pdf|Nr. 16]]
|1989-05-26
|Time Machine
|Power Supply Modification
|The GI traces were insufficient for the current they were carrying and burning the board; the fix is to add jumper wires to help carry the load.
|-
|[[media:Sb15.pdf|Nr. 15]]
|1989-04-06
|Time Machine
|Ramp Modification
|On games prior to serial number 14092, the divider between the two ramps tends to break; the fix is to add metal protectors to protect the ramps and cover up any existing damage.
|-
|[[media:Sb14.pdf|Nr. 14]]
|1989-04-03
|Laser War
|CPU Update
|Procedure to modify the MPU to go from 2K RAM to 8K RAM (6116 RAM chip); this allows the MPU to be used on (some) later games.
|-
|[[media:Sb13.pdf|Nr. 13]]
|1988-09-09
|Secret Service
|Preventative Maintenance, E.O.S.
|Fix for issue with breaking EOS blades.
|-
|[[media:Sb12.pdf|Nr. 12]]
|1988-09-07
|Secret Service
|Fuse Change
|With a shorted transistor, solenoids being damaged due to overfusing; lower value fuse recommended.
|-
|[[media:Sb11.pdf|Nr. 11]]
|1988-06-16
|Secret Service
|Coil T.D. Chart
|Errors on coil identification chart.
|-
|[[media:Sb10.pdf|Nr. 10]]
|1988-06-15
|Secret Service
|Ball Eater Adjustment
|Recommended adjustments to ball eater assembly
|-
|[[media:Sb9.pdf|Nr. 9]]
|1988-05-27
|Secret Service
|Flipper E.O.S. Actuator
|Issue with heatshrink tubing wearing through too soon on EOS assembly; replaced with with stronger material.
|-
|[[media:Sb8.pdf|Nr. 8]]
|1988-05-12
|Secret Service
|Correction to Spinner Modification, SB 003
|Issue with no sound at power up caused by error in modification instructions in the original printing of Service Bulletin 3.
|-
|[[media:Sb7.pdf|Nr. 7]]
|1988-05-06
|Secret Service
|Flipper Assembly Change
|On games prior to serial number 10160, remove washer on flipper pawl to prevent screw from working loose.
|-
|[[media:Sb6.pdf|Nr. 6]]
|1988-04-27
|Secret Service & Laser War
|CPU Board Changeability
|How to identify 3 different versions of the MPU, and modify the Secret Service version to work in Laser War.
|-
|[[media:Sb5.pdf|Nr. 5]]
|1988-04-26
|Secret Service
|Up Post Adjustment
|Fix for issue where the up post won't latch down.
|-
|[[media:Sb4.pdf|Nr. 4]]
|1988-04-25
|Secret Service
|Ball Trap Modification
|Fix for ball trap issue near the ramp.
|-
|[[media:Sb3.pdf|Nr. 3]]
|1988-04-20
|Laser War
|Game Improvements
|Addresses several game issues & improvements. Note: an error in a modification in the original printing of Service Bulletin 3 caused a sound issue; the correction for the issue is in [[media:Sb8.pdf|Service Bulletin 8]].
|-
|[[media:Sb2.pdf|Nr. 2]]
|1988-04-18
|Secret Service
|Manual Correction
|Incorrect part numbers on Ball Saver Pop Up Post Assembly
|-
|[[media:Sb1a.pdf|Nr. 1A]]
|1988-04-12
|Secret Service
|Cross Playfield Plunger Shot
|Adjustments for shooter lane ball guide, ball trough, and kickbig (White House) area.
|-
|[[media:Sb1.pdf|Nr. 1]]
|1988-04-12
|Secret Service
|Ball Trap Modification
|Fix for ball trap issue on plastics above the White House.

|}

==Technical Info==
===The Data East Board Set===
Data East used several different board generations. It is important to be able to identify the different versions when performing diagnosis and testing. 

===The Wiring Color Code===
Data East / Sega never adopted a color coding system. Instead, the wire color was marked accordingly in the associated documentation, (ie. a white wire with a blue trace is referred to as WHT-BLU, yellow with red is YEL-RED, black is just BLK, etc.).
 

===Connector Designations===
Data East / Sega did not use a board numbering system to any of the specific boards used in a game. In other words, documentation referred to boards as the following:
*PS = Power Supply
*CPU = CPU
*PPB = Playfield Power Board
*Sound = Sound Board

The naming convention for the connector on each board is notated as CNxx followed by a consecutive number, starting with "1" (ie. CN1, CN2. . .CN10, etc.).

According to the Data East Star Trek 25th Anniversary Pinball schematics/manual pp44; there are two connectors which do not follow the CNxx designation. These are 2F1 and 2F2 which connect to the main transformer (secondary side) at the bottom of the cabinet.
====Burned Connectors====
There are several connectors which are known to go bad after 10s of years of repeated thermal cycling of the system. The connectors become fragile; connector resistance goes up and the pins either heat up and/or melt it's housing. These connectors become an intermittant issue which can cause unexpected malfunctions which are difficult to troubleshoot. Author's Star trek machine gave intermittent incorrect sound effects and display resets.

Check the secondary transformer side connector; 2F2 which is located at the bottom of the cabinet and contains 2 sets of 6.3VAC GI illumination circuits. An example of a burned connector:
[[File:DE_CN_2F2.jpg|300px|thumb|left|A Burnt 2F2 Connector]]

If this connector looks charred or looks like it got hot; replace it. At this time; a direct replacement for the connector is not known; however, A functional replacement can be purchased from Digikey under the following part numbers:

DigkeyPN MFG MFG PN ''Description'' 
[http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=A1453-ND A1453-ND] TE Connectivity 1-480703-0 ''CONN Cap 4POS 94V-2 UNI-MATE (female)'' 
[http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=A1452-ND A1452-ND] TE Connectivity 1-480702-0 ''CONN Plug 4POS 94V-2 UNI-MATE (male)'' 
[http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=A25375-ND A25375-ND] TE Connectivity 350551-3 ''CONN Socket 14-20AWG TIN Crimp'' 
[http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=A25375-ND A25375-ND] TE Connectivity 350551-3 ''CONN Socket 14-20AWG TIN Crimp'' 

You'll need 1 of each of the first two, and there is a minimum buy of 10ea of the last two of which you'll need 4ea.

 
[[File:DE_CN1_PPB.jpg|300px|thumb|left|A toasty "wafer" used at connector CN1]]
Check CN1 on the Power Supply (PS). A bad connector is shown on the left. Remove the connector. Check to ensure the rounded PCB pins are not blackened with oxidation. If the connector feels loose, it's time to replace it. An exact replacement is available. Molex part number 09-18-5121 can be acquired from Mouser.com as [http://www.mouser.com/ProductDetail/Molex/09-18-5121?qs=8D5JSrTcX2r4uVBkcKnbKA%3d%3d 538-09-18-5121] ''Pin & Socket Connectors PCB MIXTERM 12P''.

 

===Switch Matrix===

Data East uses an 8x8 switch matrix to control all switches except the test button switches and the special solenoid switches (only games which use [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Reflexive_Versus_Non-Reflexive_CPU_Boards reflexive CPU boards]). A general discussion of the switch matrix can be viewed [http://www.pinwiki.com/wiki/index.php?title=General#The_Switch_Matrix here].

===Power Supply===
Data East made several revisions to their power supplies during production to support different display (alphanumeric, small, medium, large) and flipper combinations (2, 3, 4). 

[[File:DE520-5000-00.JPG|300px|thumb|left|Data East 520-5000-00 power supply]]
[[File:DEPSSchematicMJE340MJE350.jpg|300px|thumb|right|Data East 520-5000-00 power supply schematics]] 
'''Part Number 520-5000-00''' 
This power supply was used on games with alphanumeric displays such as "The Simpsons". It creates both +100 and -100 volts to operate the plasma score displays. Typical problems with this board include:
*Burned general illumination connections and connectors.
*Pins on CN1, called a "wafer" connector, burn. You can safely exchange the unused pins at positions 5 and 8 for burned pins in a pinch.
*The fuse clips are brittle, and fracture easily or lose their tension, a common theme across all Data East power supplies.
*This power supply is compatible with the D-8345-XXX power supply from Williams and vice versa.
 

[[File:DESmallDMDPSOverview.jpg|300px|thumb|left|Data East 520-5047-00 Power Supply]]
[[File:DEPSSchematicSmallDisplay.jpg|300px|thumb|right|Data East 520-5047-00 Power Supply Schematics]]
 
'''Part Number 520-5047-00''' 
This power supply was used on the five games (Checkpoint, Teenage Mutant Ninja Turtles, Batman, Star Trek, and Hook) which used the small 128 x 16 DMD. One thing which makes this power supply stand out at a glance are the two large 10W power resistors installed on the unit. Other things which make it different from the power supply used with a "standard" 128 x 32 DMD are:
*The use of MJE340 and MJE350 high voltage transistors versus MJE15030 and MJE15031 transistors.
While compatible, the -00 should not be used as a replacement for the -01 power supply. The -01 is capable of delivering higher currents and is more robust.
 

[[File:Placeholder.jpg|300px|thumb|left|Data East 520-5047-01 Revision A Power Supply]]
[[File:500-5047-01.jpg|300px|thumb|right|Data East 520-5047-01 Power Supply Schematics]] 
'''Part Number 520-5047-01 Revision A''' 
Revision A High Voltage section:
*Has no resistor R17
*The Zener diode at D10 is a 1N4764 and is tied to ground
*Zener diode D11 is a 1N4743
*Connector CN7 has three pins to drive the GI relay on the power supply
 

[[File:DEPSRevB.jpg|300px|thumb|left|Data East 520-5047-01 Revision B Power Supply]] 
'''Part Number 520-5047-01 Revision B''' 
Revision B High Voltage section:
*Has a 1.5Kohm 1/2W resistor at R17
*The Zener diode at D10 is a 1N4743 <--- '''Note:''' Different from previous board revision
*Zener diode D11 is a 1N4764 tied to ground <--- '''Note:''' Different from previous board revision
*Connector CN7 has three pins to drive the GI relay on the power supply
 

[[File:DEPowerSupply-01RevisionC.jpg|300px|thumb|left|Data East 520-5047-01 Revision C Power Supply]] 
'''Part Number 520-5047-01 Revision C''' 
Revision C High Voltage section:
*Has a 1.5Kohm 1/2W resistor at R17
*The Zener diode at D10 is a 1N4743
*Zener diode D11 is a 1N4764 tied to ground
*Connector CN7 has three pins to drive the GI relay on the power supply
The -01 power supply is backwards compatible with games that use the -00 power supply. If the unregulated 12V on connector CN7 are not used (which is the case with most pins using the -02 power supply) it can replace the -02 too.
 

[[File:DEPowerSupply-02RevisionA.jpg|300px|thumb|left|Data East 520-5047-02 Revision A Power Supply]]
[[File:DEPSSchematic1503015031.jpg|300px|thumb|right|Data East 520-5047-02 Power Supply Schematics]]
 
'''Part Number 520-5047-02 Revision A''' 
*Has a 1.5Kohm 1/2W resistor at R17
*The Zener diode at D10 is a 1N4743
*The Zener diode at D11 is a 1N4764 tied to ground
*Connector CN7 has two additional pins that carry positive and negative unregulated 12 volts.
 

[[File:DEPowerSupply-02RevisionB.jpg|300px|thumb|left|Data East 520-5047-02 Revision B Power Supply]] 
'''Part Number 520-5047-02 Revision B''' 
The -02 power supply is backwards compatible with games that use the -00 or -01 power supply.
 

[[File:DELargeDMDPS-1.jpg|300px|thumb|left|Data East Large DMD Power Supply 520-5047-03 Revision B]]
[[File:500-5047-03.jpg|300px|thumb|right|Data East Large DMD Power Supply 520-5047-03 Schematics]] 
'''Part Number 520-5047-03 Revision B''' 
This power supply was used for Data East games with the large format DMD display. Since the large DMD displays had their own power supplies, this board did not contain circuitry to create the high voltages DMD displays require. It provides 5, 12, and -12VDC only.
 

===CPU Board===
*520-5003-00 and DE-0262-2 (Version 0) - '''Reflexive'''
[[File:DE_CPU_520-5003-00.jpg|thumb|300px|left|Data East 520-5003-00 CPU Board. The board in this pic has been modified to accept a 6264 CMOS RAM chip to properly function in a Secret Service. Note that the toroidal inductor on the +5v input has been removed.]] 

The version 0 MPU contains only 2K of CMOS battery backed RAM, that being a 6116. The board can not accommodate a larger memory chip like the 6264. Consequently, this board won't work in later production Data East games since they probably take advantage of the expanded memory.

The -00 MPU in this image has been heavily modified to accept a 6264 CMOS RAM chip. The "Data East Test PROM" does not work with this revision of the board either.
 

*520-5003-01 (Version 1) - '''Reflexive'''
[[File:DE-0262-2-CPU.JPG|thumb|300px|left|Data East 520-5003-01 CPU Board. This picture shows the first revision still labeled with "DE-0262-2". Compared to later boards marked with 520-5003-00 and 520-5003-01 part numbers, this revision has fewer jumpers.]] 
The version 1 MPU was used only for the early production run of Laser War. Later production of Laser War used the Version 2 board.
 

*520-5003-02 (Version 2) - '''Reflexive'''
[[File:De_cpu_520-5003-02.JPG|thumb|300px|left|Data East 520-5003-02 CPU Board from Time Machine]] 
This revision of the Data East MPU increased the RAM size to 8K by replacing the 6116 with a 6264 RAM. With this version, the MPU has no control over the switched solenoids (solenoids 17-22). In solenoid test, coils 17-22 will not even be noted or triggered at all. The only way to test these coils is to close each one's associated switched solenoid switches.
 

*520-5003-03 (Version 3) - '''Non-Reflexive'''
[[File:DE CPU 520-5003-03.jpg|thumb|300px|left|Data East 520-5003-03 CPU Board from Last Action Hero]] 
This revision of the Data East MPU added circuitry which could control the switched solenoids. This particular MPU board is noticeably thicker in construction than prior versions. 

[[media:DE-MPU-Schematics.pdf|520-5003-03 (Version 3) board schematics]].
 

*520-5003-04 (Version 4, a Version 3 with Version 4 label) - '''Non-Reflexive'''
[[File:De cpu 520-5003-04.JPG|thumb|300px|left|Data East 520-5003-03 CPU Board from Jurassic Park (note -04 label from factory)]] 
This revision of the Data East MPU also included circuitry which could control the switched solenoids. See the following section.
 

====Reflexive Versus Non-Reflexive CPU Boards====
Version 1 and 2 Data East CPU boards are reflexive. Simply stated, reflexive CPU boards are boards where the 6 switched coil drive transistors were enabled by a switched coil switch input. These coils were typically pop bumpers and slingshots. Each assembly had its own switch, which was not part of the switch matrix, and was responsible for enabling its associated coil when closed. This implementation is similar to Williams System 11 Special Solenoid, however, unlike System 11 hardware, the MPU has no control over the switched solenoids (solenoids 17-22). Note that with the reflexive boards, the switched solenoids were limited to the slingshots and pop bumpers. 

Version 3 boards are non-reflexive. Non-reflexive boards use 6 special coil drive transistors, however, the switches responsible for enabling these coils are part of the switch matrix. Also, the addition of a 7407 chip at 11C enables the MPU to control the switched solenoids. 

Version 3, non-reflexive boards are backwards compatible, and can be used in a game which would typically use a version 2 board. Conversely, version 2 reflexive boards are '''not''' forward compatible in games which use a version 3 board. Note that with the non-reflexive boards, the switched solenoids were not limited to just the slingshots and pop bumpers. 
 

===Mega Resistor Board (MRB-1)===
The Mega Resistor Board was only present in Data East's [[Secret Service]] to bring down the voltage from 25v from the coil transistors to 12v for the flash lamps. It was replaced by the Playfield Power Board (PPB-1) in later games.

[[File:Dataeast-mega-resistor-board.jpg|thumb|left|300px|Mega Resistor Board (MRB-1)]]
 

===SMIG Board===
On Secret Service, the MRB board did not control ground to the 50 volt coils. So on [[Laser Wars]] and [[Secret Service]] a small board called the SMIG board was used, mounted under the playfield. In addition, a backbox mounted 50 volt power board was installed. This board was identical to the 50 volt "flipper power board" used on System11 games prior to Williams' Big Guns.

===Playfield Power Board (PPB-1)===
The PPB-1 board is Data East's answer to Williams' auxiliary power supply and interconnect boards created during the System 11B era. The PPB board consists of the four GI string fuses, current limiting resistors for the flashers, up to (not all PPBs are fully populated) five TIP-36c transistors, the 50v bridge rectifier, an array of diodes and a relay for coil multiplexing, and several other 32v and 50v power fuses. Some versions added a varistor, while others didn't.

*50v coil board

*520-5015-00

[[File:PPB520-5021-00.JPG|300px|left|thumb|Data east 520-5021-00 PPB-1 Revision A board]]
[[File:DE_520-5021-00_RevB_PPB.JPG|300px|left|thumb|Data east 520-5021-00 PPB-1 Revision B board]]
 
*520-5021-00 
The only discernible difference between the 520-5021-00 Rev A and Rev B boards is the addition of a varistor on the revision B board. 

[[File:DE PPB-1 520-5021-05.JPG|300px|left|thumb|Data East 520-5021-05 PPB-1 Board]] 
*520-5021-05 
The 520-5021-05 has the addition of fuses F6 (32v flashers), F7 (32v coils and flashers), F8 (50v coils, except flippers), and F9 (50v flippers only). The source for both F8 and F9 originate from the bridge rectifier on the PPB. F5 is the fuse on the input side of the bridge. 

[[File:DEXPinPPBBoard.jpg ‎|300px|left|thumb|XPin replacement for the Data East PPB-1 Boards]] 
The XPin replacement for the OEM PPB boards uses FETs instead of TIP-36c transistors. A good replacement FET is the IRF9530, as pictured on the repaired board at left. 
 

===Sound Board===
====BSMT 2000 Sound Board Compatibility====
Other guides report that sound boards are not upwards or downwards compatible, this is not entirely true. Later boards that use the BSMT2000 DSP (520-5050-00 and later) have at least some backwards compatibility with previous BSMT2000 board versions.

For example, a 520-5077-00 board that was used in later games such as WWF Royal Rumble and has spaces for four music/speech EPROMs at U17, U21, U36, and U37 will work in an earlier game that came with version 520-5050-02 such as Jurassic Park, which uses two EPROMS at U17 and U21. All sounds and music play correctly.

An earlier board will work on later games that use more EPROMs, however some sounds will be missing since the earlier version does not have space for all EPROMs. For example, a version 520-5050-02 board used in Star Wars will work in a WWF Royal Rumble that came with later version 520-5077-00, but sounds will be missing since the 520-5050-02 only has space for two sound/music ROMs while WWF requires three music/speech ROMS for full sound capabilities.

Additional testing needs to be done to see if there are any addressing issues with earlier ROMs used in later games, or if ROMs from later games could be doubled up and used different/previous versions. But from a connectivity and electrical standpoint, there is some cross compatibility and maybe complete backwards compatibility.

'''Note:''' Despite the schematic documentation for games like Jurassic Park and Last Action Hero, all BSMT2000 based sound boards use a 10Kohm POT across pins 1, 2 and 3 of the connector labeled "POT".

[[File:DE-0288 sound board.jpg|300px|left|thumb|DE-0288-1A Sound Board]] 
DE-0288-1A Sound Board 
This sound board was developed for and used only in the early run of Laser War. 

*520-5002-01
[[File:DE 520-5002-01 Blue Sound.JPG|300px|left|thumb|Data East 520-5002-01 Earlier (Blue) Sound Board]]
[[File:DE 520-5002-01 Green Sound.JPG|300px|right|thumb|Data East 520-5002-01 Later (Green) Sound Board]]
 

[[File:LaserwarLateProductionSoundBoard.jpg|300px|left|thumb|Late production Laser War sound board ROM locations.]] 
This sound board can also be used in Data East's first electronic game, Laser War. The ROMs should be placed as shown in the image at left.
 

*520-5002-02
[[File:DE 520-5002-02 Sound.JPG|300px|left|thumb|Data East 520-5002-02 Sound Board]] 
*520-5002-03
[[File:DE 520-5002-03 Stereo Sound.JPG|300px|left|thumb|Data East 520-5002-03 Sound Board]] 

*520-5050-00
*520-5050-01
*520-5050-02
*520-5050-03

[[File:DE 520-5050-00 Sound.JPG|300px|left|thumb|Data East 520-5050-00 Sound Board]] 

[[File:DE 520-5077-00 Ebay 4-16-15.JPG|300px|left|thumb|Data East 520-5077-00 Sound Board]] 
*520-5077-00 - This board is similar to the 520-5050-0x series. It was redesigned to allow up to four 27040 EPROMs for voices and sound effects. It has a different pre-amplifier design than the 5050 series, but uses the same MB3730A power amplifiers. 

[[File:Sega_Sound_520-5126-02_Front.JPG|300px|left|thumb|Sega 520-5126-02 sound Board (Front)]]
[[File:Sega Sound 520-5126-02 Back.JPG|300px|right|thumb|Sega 520-5126-02 sound Board (Back)]] 
*520-5126-02 - This board is very similar to the 520-5077-00 design. The power amplifier section was redesigned. It is reported that it is interchangeable with the 520-5077-00. The sound section of the later White Star boardset is almost a 1:1 copy of this board. 

Starting with the 520-5050-00 DE used the BSMT2000 sound DSP. The two PAL chips on all these board revisions are identical and can be interchanged with the ones in the White Star CPU board.
 

===Solid State Flipper Board===

The solid state flipper board was used in many Data East games as well as the first two WhiteStar games, Apollo 13 and GoldenEye.

*520-5033-0x series
**520-5033-00
[[Image:DESolidStateFlipperBoard520-5033-00.jpg|300px|thumb|left|A two channel Data East Solid State Flipper Board, 520-5033-00]] 
 
*520-5033-03
This board has annoying design defect where the flippers would not work if the end of stroke switch was not making good contact. See [[Data_East/Sega#Solid_State_Flipper_Board_Issues | Solid State Flipper Board Issues]]
[[Image:DataEastFlipperBoard520-5033-03-RevisionC.jpg|300px|thumb|left|Data East 2nd Generation Solid State Flipper Board, 520-5033-03, as found on Jurassic Park]] 
 

*520-5070-00 
[[Image:520-5070-00.jpg|300px|thumb|left|Data East Solid State Flipper Board 520-5070-00]] 
The 520-5070-00 Solid State Flipper Board was supposedly only used on Last Action Hero. The board has 10 pins at CN1 as opposed to 9 pins on the more common 520-5033-00 flipper board.
 

*520-5076-00

*520-5080-00

[[Image:DEFlipperBoardRottenDogFLP023.jpg|300px|thumb|left|Data East Rottendog Aftermarket Flipper Board (FLP023)]] 
This board was re-engineered to use MOSFETs. It is compatible with a great many DE games via DIP settings.
 

===Display Board===

*DE-0264-1 Display Controller Board
[[File:DEDisplayController.jpg|thumb|left|300px|Data East Master Display Controller Board DE-0264-1]] 
This board was used exclusively for the first Data East game, Laser War. It was not used in any other game. It appears to be a direct copy of the Williams System 11 display controller board used in games like High Speed. It supports two 7-alphanumeric and two 7-numeric displays, along with the "ball in play/credit" display.
 

*520-5014-00
[[File:DE_Time_Machine_Display.JPG|thumb|left|300px|Data East 520-5014-00 Alpha-Numeric / Numeric 7 digit display]] 
520-5014-00 - Alphanumeric / numeric 7 digit display used on... Secret Service, Torpedo Alley, Time Machine, and Playboy 35th Anniversary only.
 

*520-5030-00
[[File:DE520-5030-00.JPG|thumb|left|300px|Data East 520-5030-00 Alpha-Numeric 16 digit display]] 
520-5030-00 - Alphanumeric 16 digit display used on... Monday Night Football, RoboCop, Phantom of the Opera, Back to the Future, and The Simpsons. 
 

[[File:DE 128x16 520-5042-00.JPG|thumb|left|300px|Data East 520-5042-00 128 x 16 "small" DMD Display (front)]]
[[File:DE 128x16 520-5042-00 Back.JPG|thumb|right|300px|Data East 520-5042-00 128 x 16 "small" DMD Display (back)]] 
520-5042-00 - Used for the 128x16 line dot matrix displays on... Checkpoint, Teenage Mutant Ninja Turtles, Batman, Star Trek, and Hook. 
 

[[File:128x32 DMD.JPG|thumb|left|400px|Data East 520-5052-00 128 x 32 "Standard sized" DMD Display (front)]]
[[File:DE 128x16 128x32 Comparison.JPG|thumb|right|300px|Size Comparison between 128 x 32 and 128 x 16 DMD Displays]] 
520-5052-00 - Used for the "standard" sized 128x32 line dot matrix displays on... 
Lethal Weapon 3, 
Star Wars, 
Adventures of Rocky and Bullwinkle and Friends, 
Jurassic Park, 
Last Action Hero, 
Tales from the Crypt, 
The Who's Tommy Pinball Wizard, and Guns N' Roses.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Sega 520-5075-00 192 x 64 "Large" DMD Display (front)]]
[[File:Sega_Large_DMD_Back.JPG|thumb|right|300px|Sega 520-5075-00 192 x 64 "Large" DMD Display (back)]] 
520-5075-00 - Used for the large 192x64 dot matrix display on... Maverick, Mary Shelley's Frankenstein, Batman Forever, and Baywatch. 
 

===DMD Controller Board===
[[File:Sega 520-5055-01 DMD Control Board.JPG|thumb|left|300px|Data East and Sega White Star Display Controller Board]]
[[File:AnnotatedDMDController.png|thumb|right|300px|Data East and 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]. 

520-5055-00 - Used with "standard" sized 128 x 32 dot matrix displays

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:SegaLargeDMDControllerFront.jpg ‎|300px|left|thumb|Data East Dot Matrix Controller Board used on Maverick, Baywatch, Mary Shelley's Frankenstein, and Batman Forever]]
[[File:SegaLargeDMDControllerBack.jpg ‎|300px|right|thumb|The solder side...]] 
237-0139-00 - Used with "large" sized 192 x 64 dot matrix displays. The two ceramic caps on the solder side of the board were added at the factory. Note that the populated fuse clips and installed 5A slo-blo fuse are not needed, nor are they installed on most boards.
 

===Satellite Boards===
====Shaker Motor Board====
[[File:DE Sega 520-5065-00 Shaker Motor Board.JPG|300px|thumb|left|Data East / Sega 520-5065-00 Shaker Motor Board]] 
Shaker motor board part number 520-5065-00. This single sided board is pretty simple. However, being a single sided board, it is subject to fractured solder joints on the large current limiting cement resistors. If your shaker motor is not shaking, remove this board and check for failed solder joints.
 

====Magnet Control Board====
[[File:DE 520-5068-00 Mag Board.JPG|300px|thumb|left|Data East / Sega 520-5068-00 Magnet Control Board]] 
520-5068-00 - Used on games such as Last Action Hero and Guns 'N Roses
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
Solid state pinball machines typically have a built in system for audits and adjustments. Data East/Sega used two types of auditing systems. The first system was Ease-A-Just and was used on [[Laser_War | Laser War]] through [[Mary_Shellys_Frankenstein | Mary Shelly's Frankenstein.]] The Portals system was first used in Baywatch and was used for all machines after.

====Ease-A-Just====
[[File:De_easeadjust.jpg‎|300px|thumb|left|The Ease-A-Just control panel]] 
The East-A-Just system is very similar to the menu system in Bally/Williams System 11 machines. The control panel is located in the cabinet just inside the coin door. The forward/reverse (green) button is an up/down positional switch and the step (black) button is a momentary switch. To enter the East-A-Just system press the step button. If the green button is in the down position the game will enter the diagnostics menu. If the green button is in the up position the game will enter the audits and adjustments menu. Diagnostics are game dependent so check your game manual for specifics. All games do have a switch test with the diagnostics section that can be used to [[Data_East/Sega#Switch_Issues | diagnose switch problems.]] To exit the Ease-A-Just system hold down the Step button. This will rapidly send you to the last setting and will put the game in attract mode.
 

=====Setting Free Play=====
Data East machines hide many adjustments under a 'Expand Adjustments' section, including the free play adjustment. To set free play enter the adjustments section of Ease-A-Just by pressing the black button while the green button is in the up position. This will put you in 'Audit' mode. Now put the green button in the down position (reverse) and press the black button (step). You are now in the adjustments section. The last adjustment is typically 'Expand Adjustments'. Change this adjustment to 'Yes' to see many more adjustments, including free play. Adjustment values are changed by pressing the game start button. See: [[Data_East/Sega#Expand_Audits_and_Expand_Adjustments| Expand Audits and Expand Adjustments]], below.
 

==== Portals ====
"Portals" is the name that Data East/Sega gave to what other manufactures called Audits and Adjustments. Typically, "portals" will provide "generic adjustments" along with game specific adjustments.

A brief explanation of the Portals system is in each game manual. 

===Setting the Level and Pitch of a Data East Game===
[[File:DE Apron Levels.JPG|300px|thumb|left|Bubble Levels Located Underneath the Left Apron Card]] 
The game pitch and "left/right" level indicator is sometimes located under the left apron information card.
 

==Problems and Fixes==

=== Entering Diagnostics or Audits ===

[[File:DEDiagnosticButtons.jpg|thumb|300px|left|Data East used only two coin door buttons to enter diagnostics or audits/adjustments.]] 
The two buttons pictured at left allow the operator to enter the Data East built in diagnostics or audits. The green button is an up/down latching button. When the button is latched in the down position, pressing the black button will cause the game to enter diagnostics. When the button is in the up position, pressing the black button will cause the game to enter audits & adjustments.
 

===Expand Audits and Expand Adjustments===
The Data East Audits and Adjustments settings are limited to a subset of the all that can actually be set. The "menu" can be "expanded" to review and/or change additional parameters by selecting the "Expand Audits" and "Expand Adjusts" option. When this option is presented, press the game start button. Additional Audits and Adjustments may then be accessed.

<center>
<gallery widths=400px heights=200px perrow=2 caption="Data East "Expand" Options">
File:DEExpandAudits.jpg|<center>The "Expand Audits" menu option.</center>
File:DEExpandAdjustments.jpg|<center>The "Expand Adjustments" menu option.</center>
</gallery>
</center>
 

===ROM Size and CPU Jumper Settings===
[[File:DE CPU ROM Jumpers.JPG|thumb|300px|left|Location of Jumpers J4 & J5 on Data East CPU Board]]
There is a '''simple rule''' of thumb for J4 and J5 jumper settings. This rule applies to all games which use either the version 2 or version 3 CPU board. If two game PROM chips are used at position 5B and 5C, jumper J4 must be installed and jumper J5 must be removed. This applies to games from Laser War to Batman. 

If a single game PROM chip is used at position 5C, jumper J5 must be installed and jumper J4 must be removed. This applies to games from Star Trek 25th Anniversary to Batman Forever. 

The exception to the rule is Laser War. If a version 1 CPU is used in Laser War, only PROM chip 5C is used. The jumper settings should be J4, J6a, and J7a installed, and J5, J6, and J7b removed. If a version 2 CPU is used in Laser War, and PROMs are used at positions 5B and 5C, jumpers J4, J5a, and J6a must be installed. Likewise, jumpers J5, J5b, and J6b must be removed.
 

====Burning Dual ROMs into a Single 5C ROM (aka "The EasyTM Button")====

There is an easy and convenient way to eliminate futzing with jumpers after the first the time. That is to install jumper J5, remove jumper J4, and burn the game's software into a single 27512 EPROM. The Data East "Test PROM" works with this configuration as does Leon's Test ROM.

The general command to accomplish this in a "DOS box" is...

*copy /b ROM-at-5B-Image.256 + ROM-at-5C-Image.256 SINGLE-ROM-at-5C-Image.512

For earlier games, like "The Simpsons", that used a 27128 at location 5B, simply double the 27128 image during the copy command to fill the entire 27512 image. That is...

*copy /b ROM-at-5B-Image.128 + ROM-at-5B-Image.128 + ROM-at-5C-Image.256 SINGLE-ROM-at-5C-Image.512

===Power Problems===

====Fuse Clips====
Data East used fuse clips on circuit boards as opposed to fuse holders. These clips are prone to cracking and causing intermittent connections. They cannot be repaired, and should be replaced when cracked. The clips do have a correct orientation. When installing them make sure the "tabs" on the portion that grasps the fuse is oriented outwards. Inserting a blown fuse between the clips when installing new ones helps with achieving the required spacing, and ensuring that the clips do not get installed "backwards". 

Fuse clips are located on the power supply, playfield power board (PPB), solid state flipper board, and some of the satellite boards. 

====PPB Board Issues====
Common issues include:

* Burnt GI connector [[#Burned_Connectors]]
* Dead or shorted TIP36C transistor
* Bad / broken fuse clips
* Cracked header pins (cold solder joints)
* Burnt board from overfusing fuse F5

=====Fuses on the PPB Board=====
The documentation for the PPB board in several Data East games is very lacking. In some cases, the fuse value is not illustrated, while in other cases, the fuses are not even shown in the schematics at all. The fuse values should be the following:

*F1 - 5A Slo-Blo (GI Lamp Circuit)
*F2 - 5A Slo-Blo (GI Lamp Circuit)
*F3 - 5A Slo-Blo (GI Lamp Circuit)
*F4 - 5A Slo-Blo (GI Lamp Circuit)
*F5 - 5A Slo-Blo (50V Coils - Pre Bridge Rectifier BR1)
*F6 - 5A Slo-Blo (32V Flashers - Post Relay)
*F7 - 3A Slo-Blo (32V Coils and Flashers - Pre Relay)
*F8 - 4A Slo-Blo (50V Coils - Post Bridge Rectifier BR1)
*F9 - 5A Slo-Blo (50V Coils - Including Flippers - Post Bridge Rectifier)

Early PPB boards did not have fuse designations at F7, F8, and F9

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:LaserWarBridges.jpg|right|thumb|300px|The two bridge rectifiers used on Laser War. Note that the left bridge has been replaced and that fuses have not been installed (yet).]] 
A design flaw copied from the Williams design was the lack of fuses on the two bridge rectifiers used for the solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow, but that's not always the case. If the primary power fuse fails to blow, the wiring from the transformer to the bridge becomes the fuse. The end result is not pretty!

Only Laser War and Secret Service are affected by this. For the solenoid bridge, interrupt one of the AC input lines and install a fuse holder with an 8 amp slo-blo fuse installed. For the controlled lamp bridge, install a fuse holder with an 8 amp slo-blo fuse on one of its AC lines too.
 

===Power Supply Issues===

====Voltage Selection Jumper Pinout====

The 9 pin connectors used are Molex 19-09-2099 (butterfly connection w/jumpers) and Molex 19-09-1099 (connection on transformer pigtail).
[[File:DEPowerSelectionJumpers120V.jpg|300px|thumb|left|9 Pin DE Transformer Power Configuration, configured for US 115V systems.]]
[[File:230VDEPowerSelection.jpg|300px|thumb|right|9 Pin DE Transformer Power Configuration, configured for European 230V systems. Pins 3 and 9 are jumped together.]] 
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
 

====Similarity to the Williams System 11 Power Supply ====

The Data East Power Supply is very similar to the Williams System 11 Power Supply. It creates (or passes on) all of the voltages necessary for the game to operate, including...
*5VDC for the MPU (12VDC is not used / needed with a Data East MPU board - no "on board" sound circuitry and reset circuit only uses 5VDC)
*5, 12, 68, -98, and -110VDC for the Dot Matrix Display (for games with a standard 128 x 32 or a small 128 x 16 DMD display)
*18VDC for the lamp matrix
*34VDC for coils
*6VAC (or so) for general illumination lamps
*5, 12, and -12VDC for the sound board
*5VDC for the DMD controller board (games which use a standard 128 x 32 DMD display)
*12VDC for the large 192 x 64 DMD display

The power supply also contains a 24VDC relay used to turn general illumination on/off.

The 5VDC power circuit explained...
*The board receives about 9VAC at CN1, pins 10 and 11.
*9VAC is full wave rectified into about 12 and -12VDC by the bridge rectifier at DB1.
*The 9VAC continues to capacitor C2, a 100uf/25V electrolytic cap that is used as part of a voltage doubler circuit that provides operating power for the LM723 5V regulator. D2, D3 and C3 comprise the remaining components of the Greinacher type voltage doubler. Failure of any of these four components will cut power to the LM723 regulator and affect 5VDC operation.
*Unregulated 12VDC is presented to the LM723 5V regulator at pins 11 and 12.
*R6 is used for short circuit detection. Under ideal conditions (output not shorted or overloaded), there should be a very small voltage drop across R6. If the power supply is shorted -- there will be a large voltage drop across R6. Pin 3 of the regulator will detect the difference and turn down the series pass transistor TR5 in the presence of a shorted output.
*R2 and R3 are connected to the LM723 in a voltage dividing configuration. R2 and R3 together with R4 establish the output voltage levels (5VDC)

==== "Arcing" on the 520-5000-00 Power Supply ====

[[File:DE-PS-520-5000-00-Rehabbed.jpg|300px|thumb|left|A rehabbed DE 520-5000-00 Power Supply that exhibited arcing due to a leaky electrolytic capacitor.]]
[[File:DEcorrodedPS.jpg|300px|thumb|right|The corroded DE 520-5000-00 Power Supply prior to rehab. The area where power arced is clearly burned (circled in yellow), and liquid electrolyte can be seen near the bottom of the board.]] 
A problem that might be unique to this particular version of the Data East power supply is that sometimes an electrolytic capacitor on the board will leak, arcing, and creating a short between the horizontal trace and a "via" circled at left. This shorts high voltage to the -12VDC power circuit and may result in C53 on the sound board being damaged. Sometimes, the electrolyte on the board will cause it to "sparkle" when power is turned on.

Note that in the picture, the trace has been partially removed, along with the through hole, and a jumper placed on the back of the board connecting the bottom (unbanded side) of D8 to the left side of the 680 ohm resistor at R13 (shown with the red line).

The electrolytic contents as well as any carbon created by the arcing must be completely removed, necessitating a radical traceectomy like this at times.
 

[[File:DEPSCloseUp.jpg|300px|thumb|left|A closeup of yet another 520-5000-00 power supply with a electrolytic cap at C7. The damage hasn't caused a problem on this board yet, but soon will.]]
 

====Missing 5VDC - Leaky C2====
[[File:DESmallDMDPSPartsIdentification.jpg|300px|thumb|left|An overview of the DE small DMD power supply components.]] 
An overview of the power supply.
 

[[File:Leaking5VPSCapacitorGodsEyeCaptioned.jpg|300px|thumb|left|God's eye view of capacitor C2, leaking.]] 
[[File:Leaking5VPSCapacitor.jpg|300px|thumb|left|A second view of C2, leaking.]] 
A common reason for the lack of 5VDC is failure of the capacitor at C2. This 100uf/25V cap sometimes fails and begins to leak it's contents onto the circuit board. After a period of time, the caustic contents of the cap begin to eat into the board's copper traces. Eventually, the 5V generation path is severed.
 

[[File:DEPSEatenTraceAtC2.jpg|300px|thumb|left|Closeup of trace completely severed at C2.]]
[[File:DEC2OnAlphaNumericBoard.jpg|300px|thumb|right|Closeup of trace completely severed at C2 on an Alphanumeric version of the power supply.]] 
These pictures show the 5VDC trace completely severed by the hungry caustic leakage from C2 (left) and enough damage to cause the circuit to open (right).
 

[[File:DEPowerSupply5VDCSectionCaptioned.jpg|300px|thumb|left|A portion of the DE Power Supply schematic, with C2 circled.]] 
Note C2, circled in the schematics at left, and it's position in the 5V generation path. It's failure interrupts the path.
 

[[File:DELM723Position.jpg|300px|thumb|left|The LM723 5VDC voltage regulator.]] 
Another common cause for loss of 5VDC power is failure of the LM723 regulator. Measure and compare the DC voltage at pins 4 and 5 of the regulator relative to board ground. If the voltages differ, the regulator has failed. Socket and replace the regulator.
 

====Low or Missing 5VDC====

If you have low or missing 5VDC, the game may reset or will generally not function properly. Several components could be the root cause for this condition. Ordered in probability of failure, examine...
*fuses at F1 and F2, both 7ASB fuses. Remove them and buzz them with an ohmmeter. If blown, replace and retest. If one or both blow again at power on, there is a good chance that the bridge rectifier is shorted.
*C2 (100uf 25v), C3 (47uf 63V), and C7 (330uf 25V). These caps tend to leak their corrosive contents on the PCB and kill the 5VDC circuit. Replacing these three caps is always recommended when 5VDC problems occur.
*bridge rectifier (DB1, CM3501). Test the bridge first. Lug style bridges are tough to remove while avoiding board damage.
*LM723 voltage regulator. If the DC voltage with respect to ground at pins 4 and 5 differ, the regulator has failed.
*TR5 (2N6057) on the power supply board (use 2N6059 or 2N6284 to replace obsolete 2N6057),
*C1 (1000uf 25V) can also be replaced when you have problems with the -12V supply too.

Another condition affecting the 5VDC power circuit is failure of the 18,000uf/25V smoothing capacitor at C4. This cap is probably way past it's spec life. Replacing it is advised. While the original capacitor was specified at 18,000uf, the more common 15,000uf/25V cap will work fine in this application.
 

====Burned Connector Pins====
[[File:BurnedPin10DEPowerSupply.jpg|300px|thumb|left|Burned 9VAC input pin. Often this pin is burned to a crisp. This one isn't too bad.]]
[[File:DEBurnedCN1.jpg|300px|thumb|right|A common "hack" was to cut the wire of the burned connector, then solder that wire directly to the back of the board. Ouch! Not recommended.]] 
The 12 position "wafer" connector (CN1), which provides AC power input from the transformer secondary, often ends up with burned pins. Complete replacement of this connector is recommended should it become burned. The female housing may be reused, but it's good practice to repin both sides of a burned connector.

In a pinch, "male" header pins on the CN1 wafer may be swapped with "male" header pins at CN2, pins 1, 2, 4, or 5, as those pins are never used.
 

[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at CN1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
 

[[File:GIOutputPinBurn.jpg|300px|thumb|left|Crispy General Illumination Power Connector. This connector should be replaced immediately.]] 
Data East general illumination power connectors, like many other game systems, tend to burn from long hours of continuous use at current levels higher than the connectors can handle. These connectors are caught in a death spiral of heat & tarnish which increases resistance, which increases current draw, which increases heat and tarnish, etc.

The only sure correction for these connectors is complete replacement of both the male and female connectors.
 

====PS 520-5047-01 - High Voltage Missing at the DMD display====
[[File:DESmallDMDPSMJE340Replacement.jpg|300px|thumb|left|A Small DMD display, with traces designed to use the MJE340 and MJE350 transistors. The MJE350 on the right (at TR4) has been replaced by an MJE15031, necessitating reversal of the part and heat sink.]] 
The following sections discuss using an MJE340/350 in place of an MJE15030/1 or vice-versa. While these transistors are interchangeable, if one is used to replace the other in a board specifically designed for one type, the part must be reversed. This will necessitate reversing the heat sink also, as shown at left.
 

[[File:DESmallDMDPSMJE340-350.jpg|300px|thumb|left|A Small DMD power supply, which uses MJE340 and MJE350 transistors at TR3 and TR4 (the parts screwed to heat sinks).]] 
The small DMD power supply uses MJE340 and MJE350 transistors to create the high voltages. Note the lack of the larger "tab" heat sinks that the beefier MJE15030 and MJE15031 parts feature.
 

=====Testing DMD HV Power=====

[[File:TestingDMDVoltagesAtTheDMDConnector.jpg|300px|thumb|left|Testing DMD Display 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|300px|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. This manifests as a "plasma" look on the display, as shown on the left. Note that this looks very much like an outgassed display. 

The dot matrix display needs three voltages to operate. You can find the specification for 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.

{| class="wikitable"
!Function
! Pin 
! nominal voltage 
!Notes
|-
|  Anode || <center>1</center> || <center>'''-110V'''</center> ||  
|-
|  12VDC Offset  || <center>2</center> || <center>'''-98V'''</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> ||
|-
|  12VDC || <center>7</center> || <center>'''12V'''</center> ||
|-
|  Cathode || <center>8</center> || <center>'''68V'''</center> ||  
|}

[[File:LowHVSupply.jpg|300px|thumb|left|Measuring for 68VDC, 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". Note: this is a Williams display but the procedure is identical for Data East games.]] 
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 power supply male header pins. If the voltages return to nominal DE 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 power supply 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 power with a known good display to isolate the fault to either the DMD power or to the display panel.

For the 68V and -110V circuits Data East copied their 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.
 

=====Missing +68V for DMD Display Power=====
'''Warning''' Be extremely careful not to touch anything when working on live High Voltage (HV) circuits.

Assuming it's not the transfomer, connectors or fuses then you should be able to measure a +DC High Voltage (HV) at the banded side of D5 with respect to GND.

If no voltage there, suspect fuses and then test D5 on the diode setting and replace D5 with a 1n4004 diode. Also test, and replace D7 with a 1n4004 diode at the same time for good measure as it's a penny part and probably stressed. Same procedure although it rectifies the a -DC HV.

'''Measurements are with respect to ground.'''
You should now have a HV +DC reading at the banded side of D5. Test for +68v output.
You should also have a HV -DC reading at the non-banded side of D7. Test for -110v and -98v DC output.

Do not be concerned if measured voltages are not exact without a DMD connected, they will read lower under load. It can also be that the DMD display itself is faulty and taking down the PSU.

Capacitors C10 / C11 are important, if you can't test then replace them. Especially if it looks to bulge at ends, old capacitors dry out and then fail. C10 and C11 are both 100uF @ 200v. You should be able to use 150uF at a higher voltage for these, so 150uF @250v is fine.
:'''''Observe the polarity of the capacitors you remove and mark with a Sharpie if not already indicated on PCB mask. This is very important for Electrolytic capacitors which have a polarity!'''''
D5 / C10 are for the +68v HV DC to the DMD Display.
D7 / C11 are for the -98v and -110v HV DC to the DMD Display.

: '''The circuit for +68 voltage is comprised of components under CN5 / CN6 of the Power Board (PSU).'''
{| class="wikitable"
!colspan="4" |+68v circuit
|-
!Part
!Description
!Location
!Equivalent
|-
|MJE340&dagger; || NPN transistor || TR3 || MJE15030
|-
|MPSA92 || PNP transistor ||TR1 || available
|-
|1n4760B ||68v zener diode ||D9 ||available
|-
|1n5228 ||3.9v zener diode ||D6 ||available
|-
|1n4004 ||diode 400v @ 1A ||D5 ||available
|-
|47K || resistor 1 Watt||R8 ||available
|-
|330K || resistor 0.5 (1/2) Watt ||R11 ||available
|-
|1.5K || resistor 0.5 (1/2) Watt||R12 ||available
|-
|500 ohm|| resistor 10 Watt Ceramic||R15 ||available
|-
|100uF @200v||Capacitor ||C10 ||e.g. 150uF @250v
|}

: &dagger; The MJE15030 is a heavy duty version of the MJE340 (TR3)

Check values of the above resistors. Any out of spec. (or showing open) will need to be replaced first. Test DMD again.
Then replace the 1N4760 68v and 1N5228 3.9v zener diodes and test DMD again.
Then work through the transistors, replacing TR1 then TR3 test the DMD.
If the 3.9v zener has failed it will take out TR1 and TR3. Trying to replace the transistors first will be a frustrating exercise as they will keep blowing.

=====Missing -110V or -98V for DMD Display Power=====
Follow a similar procedure to the one above. The plus and minus HV circuits are nearly 'mirror images'.

A missing -98v DC output only while reading -110v points to D11 (1n4742 12v zener diode) or R14 (4K @ 10W ceramic resistor) as faulty. Test resistor value R14 and replace if open or out of spec. Then replace D11 '''observing banded side for polarity'''.

'''The Circuit for -110 and -98 HV voltages are comprised of components under CN5 / CN6 of the Power Board (PSU).'''

{| class="wikitable"
!colspan="4" |-110v / -98v circuit
|-
!Part
!Description
!Location
!Equivalent
|-
|MJE350&dagger; || PNP transistor || TR4 || MJE15031
|-
|MPSA42 || PNP transistor ||TR2 || available
|-
|1n5379b ||110v zener diode ||D10 ||available
|-
|1n5228 ||3.9v zener diode ||D8 ||available
|-
|1n4004 ||diode 400v @ 1A ||D7 ||available
|-
|47K || resistor 1 Watt||R9 ||available
|-
|330K || resistor 0.5 (1/2) Watt ||R10 ||available
|-
|1.5K || resistor 0.5 (1/2) Watt||R13 ||available
|-
|100uF @200v||Capacitor ||C11 ||e.g. 150uF @250v
|}

: &dagger; The MJE15031 is a heavy duty version of the MJE350 (TR4)

Check values of the above resistors. Any out of spec. (or showing open) will need to be replaced first. Test DMD again.
Then replace the 1N5379B 110v and 1N5228 3.9v zener diodes and test DMD again.
Then work through the transistors, replacing TR2 then TR4, test the DMD.
Get the -100v output working first, then go after the -98v circuit.

{| class="wikitable"
!colspan="4" |-98v circuit only
|-
!Part
!Description
!Location
!Equivalent
|-
|1n4742||12v zener diode ||D11 ||available
|-
|4K || resistor 10 Watt Ceramic||R14 ||available
|}

===MPU Board Issues===

====Data East CPU Board LED Flash Sequence at Boot Up When Working Properly====
[[File:De cpu marked LEDs.JPG|thumb|300px|left|Data East CPU - Location of diagnostic LEDs]] 

Much like the Williams System 11 CPU, the Data East CPU performs a basic diagnostics procedure and produces a series of LED flashes to indicate potential boot issues. The CPU automatically tests the PIAs, RAM and EPROMs at each boot. 

With all tests passed, the LEDs illuminate in the following sequence at power-on:
* The PIA and +5V LEDs illuminate immediately
* Approximately 1/2-second later the PIA led is turned off and the Blanking LED illuminates
* +5V and Blanking LEDs are illuminated until the game is turned off.
* If a failure is detected on major board components, the PIA LED will display a flash code: 
{| class="wikitable"
!colspan="3" |PIA LED Flash Sequence
|-
!PIA LED
!Suspect Component
!Location
|-
|Stays On || One of the 6821 PIAs || various
|-
|Flashes 1 Time || 6064 RAM || 5D
|-
|Flashes 2 Times || EPROM || 5B
|-
|Flashes 3 Times || EPROM || 5C
|}
 
When the PIA LED stays on, do not assume that one of the 6821 PIAs is bad. A boot failure due to a completely unrelated error might just have occured. In fact, a bad CPU chip may cause a boot failure where the PIA LED stays on and the Blanking LED never illuminates. If the CPU chip is bad, the hard-to-find original 6808 CPU can be replaced with an easier to find 6802 CPU. The CPU board will disable the 6802's internal RAM since it ties pin 36 to ground, which effectively makes it work just like a 6808 CPU.
 
If you bench test the board you can also use WMS System 11A to 11C roms to check it out. The diagnostic routine is much superior to the one in the DE rom. If you use WMS U26 and U27 roms J4 must be set. You can combine both roms into a 27512 in which case J5 needs to be set on the DE CPU. Everything will work. Some of the special solenoids are connected to different pins but for bench testing who cares? V2 and later DE boards use a 8K ram. The WMS software will not be able to dectect errors in ram space above the 2K limit.
 

====Display Operation at Boot Up When Working Properly====

=====Alphanumeric Games=====
This is a stub.
=====Small 128 x 16 DMD Display=====
[[File:DE Sm DMD Boot Disp Ver.JPG|thumb|left|300px|Data East "small" DMD Display display code version]]
[[File:DE Sm DMD Boot CPU Ver.JPG|thumb|right|300px|Data East "small" DMD Display CPU code version]]
When a Data East game with a small 128 x 16 DMD display is powered on, the first thing shown on the screen is the display code version. Next, the CPU code version is displayed. This information is provided so the operator can verify the correct display and game software versions are installed. Once the display and game code versions have been displayed and the game has successfully booted, the controlled lamps should start to "dance". The game is now in attract mode.
 

=====Standard 128 x 32 DMD Display=====
[[File:DE Std DMD Display Version.JPG|thumb|left|300px|Data East Standard DMD Display display code version]]
[[File:DE Std DMD CPU Version.JPG|thumb|right|300px|Data East Standard DMD Display CPU code version]]
When a Data East game with a standard 128 x 32 DMD display is powered on, the first thing shown on the screen is the display code version. Next, the CPU code version is displayed. This information is provided so the operator can verify the correct display and game software versions are installed. Once the display and game code versions have been displayed and the game has successfully booted, the controlled lamps should start to "dance". The game is now in attract mode.
 

=====Large 192 x 64 DMD Display=====
TBD.

====Open the Door Message====
[[File:DE Sm DMD Open Door Message.JPG|thumb|left|300px|"Open the Door!" Message upon boot up (128 x 16 DMD)]]
Games with the smaller 128 x 16 DMD display will sometimes display a message at power up, which states "OPEN THE DOOR!". The game is requiring the user to open the coin door, before allowing the game to successfully complete the boot process. The purpose of the message is to alert the user, that the backup RAM memory has not been preserved since the last power down. Possible reasons for the memory not being preserved are: 
*Batteries are not installed.
*The batteries are providing insufficient power to retain the memory.
*The batteries are installed incorrectly and not providing power to the RAM memory.
*The battery holder is not functioning properly or has been compromised.
*The batteries have leaked.

[[File:DE Std DMD Open the Door.JPG|thumb|left|300px|"Open the Door" Message upon boot up (128 x 32 DMD)]] 
This message appears on some games with 128 x 32 standard DMD displays too (not 100% if all games have this or not). In addition to the message on the DMD, the controlled lamps will not strobe until the boot sequence has successfully completed.
 

You should be able to open the coin door then close the door, and the game will complete boot up.

If you've ruled out the batteries (as stated above) as the reason for seeing this message, there are other possible causes.

First, check diode D25 which is located just to the right of the batteries. You can remove the batteries and check the diode with your meter set to "diode check" the traditional way. Or, you could set your meter to DC volts, place the black lead on the ground TP at the top of the board, and place the red lead on the banded side of D25. Your meter should read about 4.2VDC. Now move the red lead to the non-banded side of D25. Your meter should read about 4.6VDC. The difference between 4.2VDC and 4.6VDC is the typical .5 to .7 VDC drop across the diode. If that voltage drop isn't measured, or the firs measurement was zero, then the diode has failed open and is not allowing battery backup current to flow.

Finally, measure for about 4.2VDC on the bottom right pin for the RAM at location 5D. RAM 5D is located just below the game ROM. If you measure 4.2VDC at D25 and not at RAM 5D, then there is a break in the PCB trace between the two, or the RAM socket has failed, or the RAM isn't seated well. The chip can sometimes be moved when the game ROM is changed due to their proximity on the board. If you've completed all these steps successfully and you still see the 'Open the Door' message, there is a good possibility that the RAM chip at location 5D has failed.

==== Relocating the Battery from the MPU board ====
[[File:DE_CPU_Battery_Damage.JPG|300px|thumb|left|The aftermath of batteries which leaked]]
[[File:DE CPU Battery Damage Marked.JPG|300px|thumb|right|A detailed view of the extent of damage done. Note that the area inside the yellow rectangle is potentially at risk]] 
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. 

[[File:DE CPU Remote Battery Holder.JPG|300px|thumb|left|Data East MPU Board with Remote Battery Pack]] 
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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D25 on the MPU board fails. Keep in mind that an added secondary diode to this circuit will decrease the voltage passing to the RAM memory, if D25 is still good. 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 bottom right pad and ground (black wire) to the middle right pad. 

[[File:DE CPU D23 D25 Battery TP.JPG|300px|thumb|left|D23 and D25 Diodes Highlighted on a Data East Version 3 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D25 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D25 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D25 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 RAM memory, if D25 is still good. 

Testing the D23 diode is a good idea too. The D23 (1N5817) diode is used to keep the backup batteries from powering the MPU board when the power is off. Evidence of a failed D23 diode are batteries which fail prematurely.
 

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 '''B+''' 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 Lithium "Button Cell" Battery====
[[File:DEButtonCell.jpg|300px|thumb|left|A CR2032 installed in lieu of the typical 3 AA batteries.]] 

Another option to replace the OEM three battery pack is to use a button cell battery holder and a CR2032 lithium battery. Lithium batteries deplete differently than alkaline batteries. They tend to hold their original 3V for their entire useful life rather than decaying slowly. Once they've been depleted, the 3V power falls off rapidly.

Some button cell holders are perfectly suited for Data East MPUs. The two connection points fit directly through the available connection points on the board. Solder the positive side of the battery holder to the lower connection point. When using a lithium battery, D25 must remain in place.
 

====Installing a Remote Battery on a Laser War MPU====
[[File:DELaserWarBattery.jpg|300px|thumb|left|A CR2032 installed in lieu of the typical 3 AA batteries, on the first revision of Data East MPU used ONLY in Laser War. Note the "zero ohm jumper" connecting upper left and lower left battery through holes.]] 
The MPU in Data East's first game, Laser War, used a WMS style 3AA battery holder with all batteries oriented in one direction. The traces on the board were identical to WMS MPUs, connecting positive to negative across the batteries. This necessitates different connections when remotely locating the battery or installing a coin cell battery, as shown in the image at left. An alternative when using a wired remote holder (for instance) is to connect the positive battery lead to the upper right through hole and the negative battery lead to the lower left through hole (B1 + to B3 -)
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:DE Mem Cap Installed.JPG|300px|thumb|left|Installation of an "H" Style Memory Capacitor, and replacing D25 with a wire jumper.]] 
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 or greater (Farad) 5.5v "H" style memory capacitor. Other styles of memory caps will work, but an H style fits perfectly into the existing "+" and "-" holes where the factory battery holder was installed. When using a memory cap, blocking diode D25 must be removed (or jumped), and a 0 ohm jumper should be installed. The purpose of removing the diode is to allow the memory cap to be charged when the game is turned on.
 

[[File:DESuperCapFront.jpg|300px|thumb|left|Installation of a "Pi" Style Memory Capacitor, component side of board.]]
[[File:DESuperCapBack.jpg|300px|thumb|right|Installation of a "Pi" Style Memory Capacitor, solder side of board.]] 
Another style of memory cap has both leads coming out the bottom, spaced about 1/4" apart, and looks like the mathematic symbol for "pi" when viewed from the side. The original holes for the positive battery connection on the PCB can be quite handy for installing this type of cap. Insert the positive lead of the cap through the small hole and the negative lead of the cap through the large hole. On the solder side of the board, cut the trace between the small and large holes, and add a jumper as shown in the picture on the right. The jumper connects the negative lead of the cap to board ground. The same jumper mentioned above, replacing D25, is also required.
 

'''Note:''' Installing a 120 ohm (or so) resistor in place of the jumper (where the D25 diode was originally installed) prevents the memory capacitor from being the equivalent of a dead short when it initially charges.
 

====Data East CPU Board Alkaline Damage Area====
[[File:DEAlkalineDamageImage-Wiki.jpg|thumb|300px|left|A handy guide to assist component replacement at alkaline damage ground zero.]] 
So...you didn't get those batteries off the MPU board...for shame...for shame.

The diagram at left shows the component parts you may need to clean up the board. Typical alkaline damage abatement methods should be used (vinegar wash, scrub with brass brush, rinse vinegar away with isopropyl alcohol or LOTS of water, sand as necessary). Be sure to check under the 6808 processor socket for damage also.

Note some component parts are a bit odd, like the 33.2K resistor. A 33K resistor may be safely substituted.
 

====Blanking Signal Stuck Low or Pulsing====
[[File:De cpu mark up.JPG|thumb|right|300px|Data East CPU Board - Key Circuits Identified. Image Courtesy of Jim Palson]]
The blanking signal is a fail safe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at 1J, 2J, 3J, and 4J).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:DE-C87.jpg|thumb|left|300px|C87, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]]
In rare cases, C87 can fail. C87 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C87 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C87.

When repairing the battery damage, sometimes R3 needs to be replaced too. Note: Be sure to use a 33K resistor (three orange rings). Due to age and fade, the resistor can appear to have 3 rings of red (a 2K2 resistor), but this is incorrect. A low resistor (such as 2K2) will also cause the blanking signal to pulse. 

[[File:BlankingSignalLogic.jpg|thumb|right|300px|Data East CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will update the displays by sending data to the display 6821 PIA at 11B at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The schematics call this signal "TG".
#The signal is inverted by the 7404 at 6F, in at pin 9, out at pin 8.
#The coupling capacitor at C130 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q14 and to pin 2 of the 555 timer at 1C.
#The 555 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 11B, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation"

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at 11B, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Data_East_CPU_Board_Repair Leon's Data East test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure the board is [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#ROM_Size_and_CPU_Jumper_Settings jumpered] to match the ROM configuration and ensure that the ROM images are valid. Those two possibilities are by far the most probable once Leon's ROM runs correctly.
 

====Reset Signal Stuck Low ====
[[File:De cpu mark up.JPG|thumb|left|300px|Data East CPU Board - Key Circuits Identified]] 
Normal operation of the reset signal at pin 40 of the 6802/6808 at 3D is to start low, then go high after a split second. Detection of this low to high transition isn't possible with the typical logic probe (ala Elenco LP-560). Reset signal failure is almost always caused by alkaline corrosion on the reset generator (IC1) or the resistors and traces in that area.
 

==== Clock Signal Detection====
The MPU's clock signal is provided by an 8Mhz oscillator at location 3C. The clock signal can be detected as a logic pulse at pin 12 of the 74LS107 at location 2F. While it would seem logical that the same pulse could be detected with a logic probe at pin 2 of the 74LS107 and at pin 39 of the 6802/6808, this isn't usually the case. A more sensitive oscilloscope can however detect the signal. Generally, if the signal is present at pin 12 of the 74LS107, unless alkaline corrosion is present, it can be assumed that the signal is also present at pin 39 of the 6802/6808.

====Connecting a Logic Probe to CPU Board====

[[File:De cpu 5v ground.JPG|300px|left|thumb|Data East CPU Board - 5V and Ground Test Points]]
[[File:De cpu power logic probe.JPG|300px|right|thumb|Data East CPU Board - Logic Probe and PC Power Supply Connected]] 
Data East CPU boards have the +5V and ground test points located just above the battery holder's upper right corner and to the left of connection CN17. Connections can be made to the appropriate pins on CN17, but it is much easier just to use the test points.
 

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

[[File:De cpu 5v ground.JPG|300px|left|thumb|Data East CPU Board - 5V and Ground Test Points]]
[[File:De cpu power logic probe.JPG|300px|right|thumb|Data East CPU Board - Logic Probe and PC Power Supply Connected]] 
The only voltage needed to power a Data East CPU on the bench is +5VDC. Data East CPU boards have the +5V and ground test points located just above the battery holder's upper right corner and to the left of connection CN17. Connections can be made to the appropriate pins on CN17, but it is much easier just to use the test points.
 

====Official Data East Test ROM====
[[image:YT.png]] A video showing the operation of the Data East Factory Test ROM can be found [https://youtu.be/_SCvqhe0YkQ?si=OHL0WHxp5wxv3GGn here]. 
With power off, replace the current CPU ROM chip with this diagnostic 27512 EPROM. Note the three LED lights in the center right of the board. The far right most LED will flash as the games powers up with this diagnostic EPROM installed.

Below are the flash codes.
Completion of a flash means the associated chip has passed the diagnostic test. For example, if the LED flashes four times then stays lit, chip 11D would be bad.

There is a long pause after flash one only. After all eight flashes, the EPROM will pulse all coils, lamps and flasher bulbs in the game, one at a time in succession.

The test ROM for Data East CPU boards has the following functions. When the Test ROM is installed into a CPU board and power applied, the CPU will perform power-up self tests and then immediately go into burn-in cycles with no intervention. It is not required that the Test button be pressed in order to initiate burn-in cycles.

The power up self-test will check major components on the CPU board and flash the LED as each one appears normal. If any fail, the LED will stay on. The tests consist of a checksum test of the ROM and read/write test of the RAM and the PIA's. The PIA test will NOT check both sides of all PIA's since certain PIA ports are designed to be inputs and the loading on those ports will determine the data seen by the CPU. However, those ports designed to be outputs will be written to and read from in order that basic go/no-go functionality can be checked.

Flash -- Chip Location Tested 
1 -- C5 (ROM checksum) 
2 -- D5 (RAM read/write) 
3 -- 5F (PIA1 solenoid read/write $2100) 
4 -- 8H (PIA5 switch read/write $3002) 
5 -- 11D (PIA2 lamp read/write $2402) 
6 -- 11B (PIA3 display2 read/write $2802) 
7 -- 9B (PIA4 display1 read/write $2C02) 
8 -- 7B (PIA6 sound read/write $3402) 

The burn-in test will cycle through the solenoids, lamps, display and sounds like the present burn-in, with the following exceptions.

*The solenoid cycling will go through all the solenoid matrix positions.
*The lamps will go through all the patterns of rows and columns, as well as individual lamps; any shorts or opens will be easily seen on a test set lamp matrix board.
*If any matrix switches become closed, the lamp patterns will stop for a time. The lamp(s) corresponding to the matrix position of any closed switch(es) will be turned on. This facilitates testing of the switch matrix. A short time after the switch matrix becomes clear the lamps will go back to patterns. This also means that if any switch matrix position appears closed on power-up, the corresponding lamps will be turned on after the power-on self tests for a visual indication of where problems are located.

Written by Neil Falconer of Data East, 1/6/93

===Lamp Issues===

====General Illumination Issues====
The single largest issue with general illumination lighting in Data East games, like Williams System 11 games, is burned GI connectors at the power supply. Repinning both sides of the connector is the best solution. Be sure to use "trifurcon" crimp pins in the female .156 9-pin connector housing.

{| class="wikitable"
!<center> Pin </center>
! Wire Color at CN8    
|-
|<center>1 (top)</center> ||  Brown
|-
|<center>2</center> ||  Yellow (yellow)
|-
|<center>3</center> ||  Green
|-
|<center>4</center> ||  Violet
|-
|<center>5</center> ||  Key
|-
|<center>6</center> ||  White-Brown
|-
|<center>7</center> ||  White-Yellow (yellow)
|-
|<center>8</center> ||  White-Green
|-
|<center>9</center> ||  White-Violet
|}

[[File:DataEastGIConnectonAtPS.jpg|300px|thumb|left|A nicely repinned General Illumination (GI) connector on a Data East Power Supply.]]
[[File:DataEastGIConnectonAtPPB.jpg|300px|thumb|right|This GI connection at the PPB Board shows heat stress. Both the male and female sides of this connector should be replaced.]] 
General illumination power is sourced at the power supply board located in the upper left side of the game head. AC power comes in via a 4-pin connection at CN9. A GI relay cube on the power supply is under CPU control to switch all GI power on/off during game play. Power leaves the board at CN8, a nine pin connector (4x GI circuits plus a keying pin) and is routed through the PPB board to add fuse protection. The circuitry on the PPB board does nothing other than add fuse protection. The power enters the PPB board at J5. Each of the 4 separate GI power lanes is fused on the board. GI power then exits the PPB board through the same connector (J5).

The male connector on the PPB board (J5) is subject to cracked solder joints since the board is single sided. If you are experiencing GI issues, in addition to checking for burned connectors, wiggling J5 on the PPB board will sometimes identify the source of the problem.
 

[[File:DEGIZConnector.jpg|300px|thumb|left|A Data East Z connector. This one in the GI circuit. The only thing missing here is some marshmallows.]]
[[File:DEBurnedGIHeader.jpg|300px|thumb|right|The burned header pins on this Data East power supply prevented some of the GI circuits from working.]] 
Data East also used "Z connectors" instead of the more typical "cube" molex connectors. The example at left shows an extremely toasty GI connector between the backbox and the backbox lamp insert panel. Correct this by removing the connector completely. Solder each wire directly together, using heat shrink tubing to insulate. This connector facilitated cheap/fast manufacture and serves no purpose now, unless the user wants to remove the lamp board insert, which is highly unlikely. 

====Controlled Lamp Issues====

====Using MOSFETs in the Lamp Matrix Circuitry====
Procedure by Marco Albus 
The original Data East (and Williams) lamp matrix circuitry dissipates a lot of heat through the 27 ohm current limiting cement resistors. Often, this part of the circuit board is badly heat damaged. Using modern MOSFETs (IRF9530 or IRF9Z34N), the heat (and power consumption) can be reduced substantially.

It is possible to replace the 27 ohm resistors with simple jumpers. However, the problem with this modification is that the FETs are driven by 18 VDC Source to Gate voltage which is dangerously close to the absolute maximum rating for this part of 20 VDC (this also holds for Williams System 11 MPUs). Typical uses for these MOSFETs drive them by about 10 VDC Source to Gate voltage (or -10V for P-Channel MOSFET's used here).

[[File:DEMOSFETSchematic.jpg|300px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 wat resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vsg. 

[[File:DEMOSFETComponentSide.jpg|300px|left|thumb|1K resistors installed on the component side of the board. Image courtesy of Marco Albus.]]
[[File:DEMOSFETSolderSide.jpg|300px|right|thumb|1K resistors installed on the solder side of the board. Image courtesy of Marco Albus.]]
[[File:WMSFETInstallFront.jpg|300px|left|thumb|1K resistors installed on the component side of the board. NOTE: Data East board shown. Image courtesy of Randy Boice.]]
[[File:WMSFETInstallBack.jpg|300px|right|thumb|1K resistors installed on the solder side of the board. Image courtesy of Randy Boice.]]
Parts Required 
*8 P-Channel MOSFETs (IRF9530 or IRF9Z34N)
*16 1K Ohm 1/4 Watt resistors

Procedure 
*Remove the TIP-42 transistors
*Remove the 27 Ohm resistors
*Remove the 2.2K ohm resistor network at RA8
*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. In the pictured implementation, the upper resistor is installed on the component side between the common connection from the resistor network that was removed and the gate.
 

===Switch Issues===
Data East machines have switch testing built into its diagnostics. If a switch has not been activated in a while (typically 50 games) the machine assumes the switch has failed and displays a message when powered on. Sometimes this message can appear because a working switch hasn't been activated during play. You can manually activate the switch to clear this message.

Data East uses a switch matrix to control all switches except the test button switches and the special solenoid switches. A general discussion of the switch matrix is [[General#The_Switch_Matrix | discussed elsewhere in the PinWiki.]]

====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. It may be placed remotely at tie points underneath the playfield or on the switch itself, but a diode must be used. 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.

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.

 

====Single Switch Issues====
#For micro-switches, make sure the switch lever still works. You should hear a faint "click" when the lever is moved and the switch is activated. You can sometimes form (bend) the switch lever to make the switch require less travel to activate a closure. Note that these switches can still be bad even when the click is audible. The best thing to do is put your machine in [[Data_East/Sega#Data_East_Diagnostics_Systems | switch test mode]] and manually actuate the switch. If the game does not report the switch closure 100% correctly, replace the switch and the diode. The micro-switch (180-5064-00) on the Vertical Up Kicker (VUK) can wear out. A replacement can be sourced from DigiKey as [http://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=480-2381-ND 480-2381-ND] from Honeywell Sensing (MFG PN# V7-1C17D8-048).
#You can use a multimeter instead of the machine's built in switch test to test the switch.
##Set your DMM to continuity.
##Place one lead on the common lug (it should have the banded end of the diode)
##Place the other lead on one of the other lugs.
##The continuity setting should change when the switch is activated.
##Move the DMM lead not on the common lug to the remaining lug.
##The continuity should change and work in the opposite manner.
##Note that this test only tests the switch itself, not the circuitry responsible for reacting to a switch closure nor the wiring between the switch and other components.
#For leaf switches, make sure the contacts are adjusted properly. You can clean the contacts with a business card by putting the card between the contacts, closing the switch, and quickly removing the card.
# Check the diodes for correct orientation and that they are connected correctly. Typically the banded end of the diode goes toward the lug farthest from the common lug. Check your game's manual to be sure. Diodes do fail, but rarely. 1N4001 diodes can be replaced with 1N4002 thru 1N4007 diodes.

==== Complete (or most of a) Column/Row of Switches Not Working ====
If a complete column or row of switches are not working, determine first if the problem is on the CPU or out on the playfield.

===== On Board/Off Board Switch Matrix Problem Determination =====

The first step in diagnosing a switch matrix problem is to determine whether the problem is on the MPU or somewhere in the game wiring.

[[File:DESwitchColumnPulseTest.jpg|300px|left|thumb|Testing Data East MPU column drive circuitry using a logic probe.]] 
Testing the MPU board's column drive circuitry can be done quickly with a logic probe. Connect your probe to the 5V and Ground test points at the top of the MPU. Probing through the back of the switch column connector (green wires) should result in an identical pulse with each position tested. Note that the higher columns may not be pulsed in games that don't use the full 8-by-8 switch matrix.
 

[[File:DataEastSwitchMatrixTest.jpg|300px|left|thumb|Testing a Data East switch matrix operation by connecting a row to a column. Note that a diode is NOT necessary for this test.]] 
Testing the complete MPU switch matrix circuitry requires a jumper wire with a conductor on each end (or at least bare wires). This test will verify both the column and row circuitry on the MPU.

#Remove CN8 and CN10 from the MPU.
#Power the game on.
#Place the game in switch test.
#Using a short length of wire with a clip on at least one end, jumper pin 1 to pin 1, then pin 2 to pin 1, etc.
#Each time you jumper a pin, a single switch closure should be reported.
#If the game reports only a single switch closure each time you jumper two pins, your MPU is working fine.
#If the game reports multiple switch closures when you jumper two pins, then your MPU switch matrix has been damaged, probably by shorting high voltage to either a switch matrix row or column on the playfield. Reminder...never risk shorting high voltage to the switch matrix by working on the game with power on.
 

===== Switches Not Working Due to Playfield Wiring =====

If the problem is on the playfield, then it is likely that the column/row wire is broken or the connector is at fault. Following are several techniques you can use to find the fault.

#If a complete row/column is out, then either the female connector is bad, or the wire is broken prior to the first switch as physically wired in the game. Note that "physical" wiring order will almost certainly differ from the schematics.
#If something less than a complete row/column is out, then a wire is broken between two of the switches. Track the wire color from one switch to another or use your DMM to "buzz" between switch solder lugs of two switches. This can help you narrow the search.

==== Multiple Switches Reported from a Single Switch Closure ====
[[File:DataEastSwitchMatrixShort.jpg|300px|left|thumb|A ball trough switch bent and shorting column and row wires together. The insulator has also slipped off of the green/red wire lug. This caused multiple switch closures to be reported when only a single switch was closed.]] 
If pressing a single switch in switch test causes the game to report multiple switch closures, determine first if the problem is on the CPU or out on the playfield.

If the problem is on the playfield, inspect the likely switches to ensure that none are shorted to themselves. Check to make sure that the leads do not touch or have not been bent together and that the diode is not shorted against the common lead, as shown in the picture at left.
 

==== Periodic "Random" Slam Tilts ====
[[File:PFHangerScrewCausingSlamTiltThanksCliffy.jpg|300px|left|thumb|A real hair puller. This screw is making contact with the switch lug, resulting in "slam tilts".]] 
Thanks to a couple of folks on RGP for posting this one and to Cliffy for the picture. 

Games with playfield hangers and elevated ball troughs (ball trough is located above the playfield) similar to Star Wars, Lethal Weapon 3, Hook, etc. may "slam tilt" unexpectedly. The cause of this is a playfield hanger screw that backs out, makes contact with the lower switch lug, and completes the path to ground for the switch. This causes a "sneak circuit path" in the switch matrix and results in slam tilts as well as other switch anomalies.
 

==== Switches Seemingly Inoperative or Registering "Late" ====
[[File:SegaRollerSwitch.jpg|300px|left|thumb|Ball lock mechanism switch designations for Sega Batman Forever.]] 
Data East/Sega designed the game software to "debounce" some switches over a longer time duration. For instance, the "lock" switches on Batman Forever will not register, even in switch test, until the switch is closed for approximately 1.5 seconds. Heads up!
 

===Display Issues===
Early Data East pinball machines used alpha-numeric score displays similar to those in Bally/Williams Machines. Data East was the first pinball manufacturer to use a dot matrix display (DMD) in a pinball machine, and had three different generations of the display. Starting with Checkpoint and running through Hook, Data East used a 128x16 score display. Williams first used the common 128x32 display in Terminator 2, and Data East soon switched to this display size for the majority of their machines, (from [[Lethal_Weapon_3 | Lethal Weapon 3]] until Guns N' Roses). Data East then switched to the larger 128x64 display. This display was used in only four Data East / Sega games including: Maverick, Frankenstein, Baywatch, and Batman Forever.

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

====Outgassing Displays====
[[File:OutGassedDMDDisplay.jpg|300px|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. 

==== 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 seen 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.]
 

==== Alphanumeric Issues ====
[[File:DE520-5030-00.JPG|thumb|left|300px|Data East 520-5030-00 Alpha-Numeric 16 digit display]]
The Data East #520-5030-00 Alpha-Numeric score display board uses two 16 digit alphanumeric display glasses. 
This display was used in:
*ABC Monday Night Football
*RoboCop
*Phantom of the Opera
*Back To The Future
*The Simpsons
 

Due to many inquiries to the factory from field technicians, Sega/Data East issued [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb87.pdf Service Bulletin 87] which explained the operation of alpha-numeric displays.

[[File:DEAlphanumericSegmentIDs.jpg|300px|thumb|left|The Data East segment identification scheme, which is identical to the Williams method.]] 

Connector CN1 is the segment select for the lower score display glass. This connector handles the a, b, c, d, e, f, g, and comma segments. ICs at U1 (CD4050), U5 (CD4050), U16 (UDN7180 operating on -100v), and U17 (UDN7180 operating on -100v) as well as resistors R1 through R8 (18k, 1/2 watt) all handle this portion of the circuit.

Connector CN2 is the digit select for digits D1, D2, D3, D4, D5, D6, D7, and D8. The circuitry handling this function consists of resistors R9 through R16 (18k, 1/2 watt), ICs U4 (CD4001), U3 (CD4001), U15 (UDN6118 for the lower display, operating at +90v), and U11 (UDN6118 for the upper display, operating at +90v).

Connector CN3 is the digit select for digits D9, D10, D11, D12, D13, D14, D15, and D16. The circuitry handling this function consists of resistors R17 through R24 (18k, 1/2 watt), ICs U9 (CD4001), U10 (CD4001), U18 (UDN6118 for the lower display, operating at +90v), and U14 (UDN6118 for the upper display, operating at +90v).

Connector CN5 (ribbon cable) provides the remaining segment selects for both displays. This controls segments h, j, k, m, n, p, r, and dot (lower display only) and a, b, c, d, e, f, g, h, j, k, m, n, p, r, dot, and comma (upper display only). The circuitry handling this function consists of resistors R25 through R32 (18k, 1/2 watt for lower display only), ICs U2 (CD4050), U1 (CD4050), U5 (CD4050) for the lower display, U16 (UDN7180 operating on -100 volts), U17 (UDN7180 operating on -100 volts) for the lower display, U6 (CD4050), U7 (CD4050), U8 (CD4050) for the upper display, U12 (UDN7180 operating on -100 volts), and U13 (UDN7180 operating on -100 volts) for the upper display.
 

Connector CN4 provides power. Note: Zener diode D1 (type 1N4740) on the board regulates the +100 volts down to +90 volts.
*Pin 1: -100 volts
*Pin 2: No connection
*Pin 3: +100 volts
*Pin 4: Key
*Pin 5: Ground
*Pin 6: +5 volts

The 16 digit alpha-numeric display glass is becoming very expensive. If it is too costly to repair your original display panel, quite a number of aftermarket displays are available. These are plug-n-play compatible with the original board and has the advantage of no longer requiring high voltages (+100/-100) from the power supply.
 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

==== Dot Matrix Issues ====
Although Data East board designs share many similarities between Bally/Williams, the score display CPU is implemented very differently. Data East has a separate board and CPU for controlling the dot matrix display (DMD). This board is mounted behind the DMD on the score panel. The main CPU and this daughterboard communicate through a ribbon cable. Because of this, it is important that your CPU and display roms are the same version, or are in sync with each other. Running different ROM versions can cause some strange display issues. Ribbon cables are known to have faults, so reseating or swapping the cable may fix some issues. 

===== 128x16 (Small DMD) issues =====
The 128x16 DMD was the first DMD used in a pinball machine and was used for five games. It was replaced by the much more familiar 128x32 display.

Sometimes this display will light but the display will appear garbled. The display will flicker and move but the output will not be readable. This can be caused by the R95 resistor on the DMD controller board going out of spec. It should be a 33k 1/2 watt resistor.

===== 128x32 (Regular DMD) Issues =====
The 128x32 DMD was used in the majority of Data East machines and was the only size used by Bally/Williams. The display glass is the exact same version for both Data East and Bally/Williams and can be used as a drop in replacement. However, you will still need the DMD controller board used by Data East machines. 

[[File:de-display-romupgrade.jpg|600px|thumb|left|Before and after shots of the display board after upgrading from the stock board with two 2MB ROMs. Notice the removal of the 0 ohm resistor(jumper) at R11]] 

Some games such as Lethal Weapon 3 and Star Wars sometimes used two 27020 EPROMs at locations U12 and U14. You can use one EPROM instead if upgrading to newer code. If one EPROM is used, R11 should be open (nothing installed). This part can simply be cut off the board. If two EPROMs are used, R11 should be jumpered with a zero ohm resistor or a jumper wire. Why Data East called this a resistor (R11) versus a jumper, is anyone's guess. This is discussed in [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb38b.pdf Service Bulletin 38b]. 

It is worth mentioning that if two 2MBit EPROMs are used, and the R11 zero ohm jumper is not installed, the DMD will remain blank.

If you only have the images for 2 MBit EPROMS you can combine them into a single 4 MBit EPROM using the DOS/Windows copy command:

copy /b display-rom-1.020 + display-rom-0.020 display-rom-combined-0.040

The old ROM 1 images goes into the lower half. Make sure R11 is cut or your combined EPROM will not work.

 

Connection CN2 on the DMD controller board can sometimes be problematic. This is a three pin connector, and only two of the header pins are used for the +5vdc and ground. It is always a good practice to upgrade the connector pins in this housing to Trifurcon connectors. Using Trifurcon connector pins will help ensure that a more solid connection is made at CN2. Unfortunately, the existing connector housing is not reusable, and will have to be replaced when the connector pins are upgraded.
 

DMD displays require high voltage to operate correctly. 
Testing high voltage is easy. The procedure is outlined [https://www.pinwiki.com/wiki/index.php/Data_East/Sega#Testing_DMD_HV_Power here].
 

===== 192x64 (Large DMD) Issues =====
The large 192x64 DMD was used in the last four Data East pinball machines. The display is a relatively expensive part to replace, costing several times as much as the more standard 128x32 DMD. The primary difference with these displays is that the high voltages required to light the display are generated on the display panel itself. The panel needs only a single 18v DC supply. On-board boost converters generate the voltages required, effectively making repairs to the HV circuits very difficult as there is no access to the back of the board.

One of the most common issues with this display is that it will periodically go blank or reset the CPU. These issues are typically due to the logic power needed to drive the DMD controller board chips dropping below the required +5vdc. As Stern mentions in their service bulletin, the controller board runs at +5vdc, and "'likes' its 5 volts or darn near close". To overcome the issue, Stern offers an optional wiring harness to increase the reliability of the +5vdc logic power by pulling the +5vdc from an otherwise unpopulated connector on the power supply. A detailed discussion of the kit can be found in [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb106.pdf Service Bulletin 106].

Another issue with this display is when working on the game (or MPU on a bench), the display controller needs to be connected to the MPU. Otherwise, the lamp driver section will show a strange behavior. This is caused by missing data going through the address bus. When the display controller board is not connected it will cause a row (or multiple rows) to blink at a full 18V for a 1/2 second every second (heartbeat) making the lamps burn very brightly (18V at 6V lamps) and burn them out.

The 4-pin PC/Computer style power connection on the back of the large DMD connects to the following voltages.
*pin 1 - 5VDC
*pin 2 - Ground
*pin 3 - Ground
*pin 4 - 18 to 24VDC (Cherry/Babcock/Dale were all slightly different)
 

===Solenoid Issues===

====Drive Transistor Manufacturers====
[[File:ST-TIP122.jpg ‎‎|300px|thumb|left| One of the choices of drive transistor used by Data East.]] 
Data East used several brands of drive transistors, with most of the parts being TIP-122s and sometimes BDX-53Cs.
 

====Knocker "knocks" in test but not in game play====
Adjustment 4 in some games can be set to CREDIT, EXTRA BALL, NONE, or SPECIAL. 
If set to NONE, the knocker will not "knock" when free games are earned.
 

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game.
 

==== Driver Transistor "Quick Check" ====
You can quickly test the TIP102/TIP122 transistors (Q8-Q13, Q23-Q30, Q39-Q46, Q72-Q79) on the MPU by...
* Turn the game OFF
* Set your DMM to Ohms/Continuity buzz
* Attach the black lead to one of the metal grounding straps (crocodile clips are helpful here), there should be one in the backbox you can use
* Touch the red lead to the metal tabs of the TIP122/TIP102's
* Any continuity indicates a shorted transistor that should be replaced. Should the game be powered on, the associated coil, flasher, motor, etc will be turned on.

[[File:YT.png]] A video demonstrating this technique on a Data East MPU can be viewed [https://youtu.be/VXiS04-yY58 here].

You may also need to replace the pre-driver transistor (2n4401) that the failed transistor is connected to. It is also wise to check the wiring and the coil before powering back on, otherwise you may blow the transistor you just replaced.

See [http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_coil Testing a coil]

====Flipper Issues====
[[File:DE_Early_Single_Wound_Flipper_Coil.JPG|300px|left|thumb|Flipper Coil using the earliest "Deger" design (Monday Night Football)]] 
Data East was the first company to use solid state flippers. Starting with Playboy 35 Anniversary, Data East flippers began using a single wound coil instead of the high/low windings found in earlier games and Bally/Williams games. This single wound flipper coil design was developed by Kurt Deger, and is commonly referred to as the Deger design. Although it has gone through some transformation over the years, it is found in most of the Data East games. [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb62.pdf Service Bulletin 62] contains a listing of flipper coil parts for Data East games and shows the evolution. 

The patent for the original Deger design can be viewed [http://www.google.com/patents/US4895369 here].
 

When a Data East flipper is energized, 50 volts is sent to the coil for the initial flip. The FFASI board then drops the voltage to 9 volts so that the flipper may be held up for a long period of time without burning the coil. This voltage drop occurs after 40 milliseconds, is CPU controlled, and cannot be adjusted. This is similar to the Bally/Williams WPC FlipTronics II design where the flipper hold is controlled by the FlipTronics II board. Still, many note a different feel between Data East and Bally/Williams flippers.

Data East eventually did add an EOS switch to its flipper design beginning with Jurassic Park. This does differ from Bally/Williams in that the switch is normally closed in Data East games. This was done because certain game features fired the ball quickly back to the flippers. If the ball hit the flippers and moved them 1/16 of a inch the EOS switch would open and 50 volts would again be delivered to the flipper. This is discussed along with the general theory of Data East flipper operation in [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb49.pdf Service Bulletin 49]. With this design if the hold voltage is broken and the EOS is badly adjusted, you may experience 'machine gun flippers'.

=====Solid State Flipper Board Issues=====
These flippers are controlled by the solid state flipper board (TY-FFASI board) which is mounted in the cabinet. The board is prone to a few failures, but it's a fairly simple circuit so fixing it is normally quite easy. You should see a red LED illuminate briefly when the flipper buttons are pressed.

Early Data East flipper boards had an annoying design defect where the flippers would not work if the end of stroke switch was not making good contact. It causes problems because a flaky or broken EOS would make the flippers not work at all. DE released [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb54.pdf Service Bulletin 54] to show how to modify the existing flipper board. Or you can use a later flipper board (such as 520-5076-00) as long as it supports at least 3 flippers.

To test the flipper board:

* Remove the board from the cabinet (it's much easier to work on)
* [[Beginner%27s_Notes#Fuses | Check all the fuses]] on the board, 4 in total (2 power, 2 hold). Also check the [[#Fuse_Clips| fuse clips.]]
* Check all transistors using a DMM
* Check tracks for continuity and corrosion
* Replace board back into cabinet and power on game
* Enter Diagnostics (so power is sent to the flippers)
* Check for 50VDC at the coil lugs (DMM set to DC volts, black lead on game ground, red lead on banded side of coil diode)
* Press flipper button and check for about 8VDC hold voltage
* Check power/hold voltage on flipper board (DMM set to DC volts, black lead on game ground, red lead on CN2 pins 6&7 (8VDC hold), CN2 pins 8&9 (50VDC power stroke)

If you have no voltage on CN2-8 and CN2-9, check the PPB board J7-1 and J7-5.

[[File: DE-SSFB-9VAC-Power.jpg|300px|thumb|Right|9VAC power split to supply both the SSFB and the backbox power supply at CN1.]] 
If you have no hold voltage on CN2-6 of the flipper board, check the Power Supply board CN1-10 and CN1-11. Also, ensure the power “T-Connector” that can be found in the cabinet as pictured at right is still connected and passing power. This connector can be dislodged when raising the playfield. 

If you have no hold voltage on the coil lugs, check the hold fuses on the TY-FFASI board.

Note: The newer 520-5080-00 (EOS) flipper board can be modified to work in games requiring the 520-5033-00 (non-EOS) flipper board. Steps to do this can be found in [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb103.pdf Service Bulletin #103.]

=====Pathetically Weak Flippers=====
One cause of very week flippers in games that use the solid state flipper board, is lack of good ground for the flipper cabinet switches.

A ground connection is daisy-chained through the flipper cabinet switches. This ground then proceeds to the solid state flipper board (where an IDC connector is used...something to investigate), and then onto the general game ground. Without a solid ground for the flipper cabinet switches, a weak power pulse may be all that is delivered to the flipper coils.

The fuse clips on many Data East boards are often weak and may snap if bent closer together. The fuse clips must mechanically hold the fuse very tightly, allowing maximum electrical current to pass. Replacing weak fuse clips is mandatory for improved game performance.

=====Flipper Stuck up (hold voltage)=====
If a flipper sticks up because of hold voltage; check the coil diode as referenced by [https://groups.google.com/forum/#!original/rec.games.pinball/3u5Oa8iQp7g/jwLzsL-scU8J Ray Johnson on 7/20/1998.] Symptom is one of the flippers (originally working ok) began to stick up. Ending game or turning off power; and the flipper returns to correct position.

The flipper rests fine; and when flipped after starting the game; the red led on the Flipper board flashes and the flipper moves - yet, +8VAC hold voltage never disappears at the COIL A or B connection.

Measure the diode at the flipper coil to make sure it's good ([http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Diode use a DVM in diode mode]). Ensure the diode leads haven't cracked due to age / vibration. Note that one leg of the diode will have to be removed from the coil to accurately test the diode.

=====Flipper Repair and Rebuilding=====

[[File:DEFlipperLinkHoggedOut.jpg|left|300px|thumb|Composite of a Data East Flipper Plunger and Link. Note how "hogged out" the large hole in the link is in the top image. The middle image shows the "slop" with the plunger pushed in. The bottom image shows the "slop" with the plunger pulled out. All three images are the same flipper plunger and link.]] 
A major contributor to weak flippers in any game, including Data East, is a damaged or "hogged out" flipper link. The picture at left shows a flipper link with about 1/8" of "slop" in it. When the flipper coil pulls the plunger in, the flipper crank doesn't begin to actuate the flipper until all of the slack caused by this slop is taken in. At the very least, replacing the link is warranted.
 

[[File:flipper-before.jpg|left|300px|thumb|Flippers at the hold position before a rebuild]]
[[File:flipperparts.jpg|right|300px|thumb|Data East Flipper Rebuild Parts - Return Spring, Plunger/Link Assembly, Coil Spring, EOS Switch, Coil Sleeve, Flipper Bushing, Coil Stop, Spring Washer]] 
A flipper rebuild is one of the easier things you can do to improve the playability of your machine. Over time the parts of a flipper will wear and need replacing. Signs of this include weak or slow flippers, flippers that do not return quickly, or flippers that travel too far. An experienced technician can just replace the needed parts but it is far easier to buy a flipper rebuild kit from a pinball supplier. These kits will contains all the parts needed for a general flipper rebuild. Flipper coils are not included in rebuild kits but are not typically needed for a repair. 

Some parts are interchangeable between Data East and Bally/Williams flippers due to the similarities in design. For example, coil sleeves, links, and plungers are the same. However the flipper bushings and coil stops, although appearing similar, are not compatible. Buying a complete flipper rebuild kit for your machine will ensure you get all the correct parts.
 

[[File:coilstops.jpg|left|300px|thumb|Used and new coil stops. Excessive wear has caused the coil stop to mushroom and allow the flipper to travel too far]]
[[File:flipperalign.jpg|right|300px|thumb|Aligning flippers on a Data East machine]] 
Below are the steps to rebuild an early Data East solid state flipper. This guide does not currently address the additional steps needed for replacing or adjusting EOS switches. 

# Remove the coil stop.
# Pull the coil away from the flipper assembly. Typically the coil does not have to be replaced, so desoldering the leads is not necessary. Remove the plastic coil sleeve from the coil. This should slide out somewhat easily, but a nut driver can be used to push it out. If you cannot remove the sleeve it may have warped due to heat issues. If this is the case, replace the coil. Always replace coil sleeves when rebuilding flippers.
# Remove the return spring.
# Loosen the allen screw that holds the flipper shaft in place. The flipper can now be removed from the top of the playfield. Remove the plunger and link assembly.
# Replace the rubber stopper where the link assembly rests.
# Clean the metal parts of the flipper assembly.
# If your existing flipper has one, remove the spring holder and put in on the new link assembly. Attach one side of the new return spring to the spring holder.
# Replace the flipper from the top of the playfield.
# Loosen the flipper bolt and replace the plunger/link assembly. Do not tighten this yet.
# Attach the other end of the return spring.
# Assemble the coil. Be sure to put the end with the lugs away from the coil stop.
# Replace the coil stop and the spring washer.
# Adjust the flippers from the top of the playfield. On Data East machines the guide holes align with the tip of the flippers. Tighten the allen screw on the link assembly to hold the flipper shaft in place.
 

[[File:WMSPlungerLinkCrankOnDEGame.jpg|300px|thumb|left|A Williams plunger/link/crank assembly and EOS switch, installed on a Data East Tales from the Crypt.]] 
As mentioned above, some Williams flipper parts can work in Data East games. In the picture at left, a Williams plunger/link/crank assembly and EOS switch have been substituted. To make this work, the EOS "finger" on the crank must be bent straight and the EOS switch position must be adjusted. It works surprisingly well. The feel is very solid.
 

[[File:DE Upper Flipper.JPG|300px|thumb|left|Upper Right Flipper on a Data East game (Jurassic Park)]] 
It is worth noting that Data East games which use a solid state flipper board, and have upper flippers, do not use EOS switches on these flippers. If an upper flipper appears to be missing the EOS switch, it actually is not. This is an intended design.
 

====Ball Trough Issues====
[[File:DE 6ball Trough.JPG|300px|thumb|left|Typical Ball Trough on Later Data East Games]] 
Starting with Jurassic Park, and continuing until Apollo 13, a different type of ball trough is used. This ball trough is mounted below the plane of the playfield versus the old style, which is mounted above the playfield. The main purpose of this trough is to allow the storage of more pinballs in the trough. However, there are a whole new list of potential problems that come along with this design. 
[[File:DE Trough Ball Lock2.JPG|300px|thumb|left|Lock Ball Assy. used on Later Data East Games Where sublevel ball trough is used]] This mechanism doesn't require a coil when the ball enters the outhole, but it takes two coils to release a ball into play. One coil above the playfield releases a ball to the second coil below the playfield; the second kicks the ball into the shooter lane. This second coil has an additional switch nearby to detect the ball. On some games this is a microswitch, but on later games it is an opto.
 This arrangement has similar geometry to the later (Apollo 13) trough, as well as the Williams trough that started with Indiana Jones, but the extra (ball release) coil makes it a little harder to work on, and not quite as reliable.
 
[[File:DE Ball Trough Divots.JPG|300px|thumb|left|Data East / Sega Ball Trough with Ball Divots (Jurassic Park)]] 
[[File:Sega_Baywatch_Opto_1.jpg|300px|thumb|left|Sega Baywatch ball trough opto]] 
When the VUK at the end of the ball trough pops over and over, the game thinks there is a ball in the end position, and is trying repeatedly to clear it. It's possible that the opto is not aligned properly, or that the solder joints at the connector have failed or are cracked. It is also possible that the solder joints for one or more SMD components on the opto board have fractured, which are very difficult to see, even under strong magnification. Reflowing the solder points can sometimes solve this problem. If reflowing the solder joints does not resolve the issue, replacement of the opto pair is recommended. When replacing the ultra brite red LEDs, replace both the transmitter and receiver, These can be acquired from GPE under part # MV8114.
 
Another issue with the switch next to the VUK is possible when the switch can't close. This switch must close for the game to detect the ball and kick it into play on cue. If the game goes through ball searches when it should be kicking a ball into play, it may be that this switch needs to be adjusted.

====Flasher Issues====
Data East games usually have 4 flash lamps wired in parallel off an individual coil driver circuit. It is critical that all 4 (or at least 3) flash lamps are working on each circuit, otherwise you run the risk of all of the bulbs on that circuit burning out quickly due to the increased load each working bulb has to bear. Frequently, you will pick up a Data East game where many of the flash lamps are burned out. A common mistake when checking and replacing flash lamps on these games is to replace a single burned out flash lamp, only to find out when testing it, that it will light once and burn out, because it was the only working flash lamp on that circuit. The solution is to check the manual for the location of all the flash lamps in that circuit and make sure at least two flash lamps (but preferably 3) on the circuit are working before testing.

=== Sound Issues ===

The Data East Sound board architecture closely resembles that of the later Sega / Stern Whitestar CPU / Sound board.

'''Note:''' Despite the schematic documentation for games like Jurassic Park and Last Action Hero, all BSMT2000 based sound boards use a 10Kohm POT across pins 1, 2 and 3 of the connector labeled "POT".

==== Boot Sound Clipped ====

Each Data East game will play a short sound clip when the sound board boots. On some titles, and maybe all titles, this sound is "clipped", or cut off. This is entirely normal and does not indicate a problem.

==== Missing or Broken Pins on the MPU-to-Sound Connector ====

[[Image:DESoundConnectorPinMissing.jpg|300px|thumb|left|Pin 19 header pin missing from the Sound Board Interface connector. This does not cause a problem.]] 
It is fairly common for the MPU board to have pin 19 missing from connection CN21. This is the ribbon cable connection between the MPU and the sound board. While this seems odd, it's not actually a problem, because the "E" signal carried on this pin is not used by the sound board.
 

==== Should the sound board be recapped? ====
[[Image:DataEast520-5002-01BlownC53.jpg ‎|300px|thumb|left|C53, clearly a major malfunction, has blown and spewed it's core across the board.]] 
In general, no. There are far too many caps and far too small potential benefit derived from recapping a Data East sound board. Some caps convey signals from the solder side to the component side of the board. Tearing the through-hole of of one of these caps can render the sound board inoperative.

Additionally, with the great many caps, it is fairly easy to install a cap with reverse polarity. Sometimes the cap reacts by exploding as pictured at left. Sometimes the cap simply doesn't do it's job correctly. In particular, a 4.7uf cap in the reset circuit, if installed with reverse polarity, will cause the board to boot intermittently.
 

==== Shorted 5V Circuit ====

[[File:DESoundC62Short.jpg|300px|thumb|left|C62 filters the 5VDC circuit and can short]] 
The power input section of all Data East sound boards is identical. The 5V power circuit includes a 100uf/35V filter capacitor. Later boards increased the spec on this capacitor to 1000uf.

This capacitor can fail in such a way as to cause a 5VDC short, blowing the power supply 5VDC fuse.
 

==== No Sound - 5077, - 5126 Sound Board and Others ====

No sound at all (other than possibly the clipped boot sound) can be due to failed RAM. If the RAM has failed, Pin 4 of the BSMT2000 chip will be stuck low when checked with a logic probe or scope.

6116 RAM can be replaced with 6264 if jumper W4 is moved to W5.

6116 RAM on the 520-5077-00 board may be prone to failure.

==== Sound Tests (alphabetical) ====
{| class="wikitable"
!Game
!Audio Demo Link
|-
| Playboy 35th Anniversary || [[file:YT.png]] [https://youtu.be/2qAVZqszEK0 Audio]
|}

==Game Specific Problems and Fixes==

Please see the [[Data_East/Sega#Games | game specific pages]] for some game specific problems.

=== Star Trek 25th Anniversary Edition blown switch matrix ===
[[File:DEStarTrekFlasherSwitchCollision.jpg|300px|thumb|left|The subject flashlamp, clearly touching this switch solder tab.]] 
The picture at left shows the flash lamp that is under the center shot to the subway, under the dilithium crystal "toy". In the picture, you can see that the flasher is touching one of the switch solder tabs. Not surprisingly, the switch matrix column driver for the green/orange column (switch drive 3) was blown. Luckily, the damage extended only back to the 2N3904 at Q53. Wrapping the flashlamp socket, or the switch solder tabs with a bit of electrical tape is a reasonable solution to prevent this potentially serious issue.
 

===Guns 'n Roses blows Q52===
If Guns 'n Roses has an issue with Q52 blowing repeatedly, check the left kicker and make sure that it is not making contact with the nearby lamp socket when it fires.

==Repair Logs==
[[Leon_Borre_Data_East_CPU_Board_Repair|CPU Board Repair]] 
[http://kcpins.com/archives/137 Data East Power Supply Rebuild] 
===Delayed or Missing Blanking Signal===
'''Time Machine CPU board''' - blanking signal would go high approximately after 7 seconds or more, (if it went high at all), after PIA diagnostic signal would go low (PIA LED would go out). For a properly functioning CPU board, the blanking signal should go high immediately after the PIA signal changes its state from high to low. 

'''Resolution:''' a bad '''AMI''' 6808 CPU chip. Beware of failing AMI chips. It is rumored that AMI chips have higher failure rates than most other manufacturers. This ultimately was a simple fix, but after extensive troubleshooting was performed first. This particular fix is more of an exception than the rule. Generally, a missing blanking signal should be isolated to the blanking generator circuitry (555 timer chip, 2N4403, etc.). 

===Incorrect Flipper Pawl Screw Installed===
'''Jurassic Park''', but applies to other games
[[File:DE Flippers Incorrect.JPG|300px|thumb|left|Data East Flippers with Extra Long Screws Used on Flipper Pawls]]
This falls under the "not too often category", but it is worth mentioning. The screws used to tighten the flipper pawls have a dual duty. They of course secure the flipper pawls to the flipper bat, but they also open the flipper EOS switch. 

There were two problems with flippers on this game, as can be seen in the pic on the left. First, the screws used were Phillips head screws. A Phillips head screw does not allow for enough torque to adequately secure the flipper pawl to the flipper bat shaft. The factory screws used are #10-32 x 3/4" hardened steel socket head hex Allen screws. In using an Allen screw, chances of stripping the head are minimized, and much more torque can be applied when tightening. The second problem was that the replacement flipper pawl screws were too long. By using a longer screw, it messes with the solid state flipper board's timing, because the EOS switch is opened prematurely. The end result was a weak spastic flipper.
 

'''Resolution: ''' Installed the proper #10-32 x 3/4" hardened steel socket head hex Allen screw on both flipper assys.
 

===Broken/Missing Backbox Latches===
'''Monday Night Football''', but also applies to other early Data East cabinets.
Machine came in with completely missing backbox latches. The Data East backbox latches are very flimsy and easily stripped out of the wood. 

'''Resolution:''' Use Williams parts instead. Use # 20-9347 Toggle Latch and # 01-8397 Toggle Bracket. They are wider and beefier which provide better securing of the backbox.
 

===CPU fails to boot with RAM installed===
'''CPU board''' - without the RAM the board runs perfectly with running Leons test ROM installed. However, installing the RAM prevents the board from booting. The PIA and +5V LEDs light. The blanking LED is off. 

'''Resolution:''' a failed '''AMI''' 6808 CPU chip can cause this behavior. Beware of failing AMI chips. It is rumored that AMI chips fail more frequently than other brands. While this behavior seems odd, the failed 6808 was tested using two different known good RAM modules.
 

===DMD missing, one player game score fonts===
'''Data East Star Wars - (1.02) roms, with Rottendog MPU004 - 3 board''' 
Game plays fine, except during one player games the animated score fonts are missing.
With two player games, the player one score fonts would not show, til player two was up.
Isolated the problem down to a bad Rottendog MPU004 - 3 board.
Tested continuity from CN22 to all associated components, etc.
Rotated all the PIA's W65C21N6TPG-14 and tested the MPU board, to no avail. 

'''Resolution:''' Replaced the PIA at 9B W65C21N6TPG-14 with a MC6821 PIA. The DMD now works correctly.

Williams System 3 - 7

2026-05-11T04:47:21Z

Diz: /* Boards - added other vendors */

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:
[https://web.archive.org/web/20171113074532/https://tuukan.fliput.net/wms_en.html Tukkan.fliput.net (archived link)]

=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 || Uses 50v Flipper Power Supply Board ||
|-
|[[Star Light]]|| 06-1984 || 530 || Type 2 Sound || Uses 50v Flipper Power Supply Board ||
|}

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] [[media:Williams_1980_Parts_Catalog.pdf|PDF]]
|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. The catalog has a black cover.

|}

==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]

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

The "official" ROM repository is at Planetary Pinball and can be found [http://www.planetarypinball.com/mm5/Williams/tech/roms.html here].

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 within the 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 2K EPROM (or 2732 4K if the image is doubled) 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 contained within the Flipper ROMs. 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.

Since production runs were so large, 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 relatively expensive in the 80's.

It is always 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. The old masked ROMs also ran hot, with heat scorching evident on the ROM labels in some cases. Also, many of the ROM sockets on the MPU boards will need to be replaced. Sockets bearing the words 'Scanbe', were of dubious quality to begin with. Thirty years later, they are long past their reliable lifetime. 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.

====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 at IC20 and a 2532 at IC17 (a 2732 can be used at position IC17 by moving jumpers).

=====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====
[[File:BlueFlipperROMsMislabeled.jpg|300px|thumb|right|Mislabeled Flipper ROMs shown in a factory Jungle Lord MPU Board. Image courtesy of PinSider rramstad]]
The blue fipper ROMs were used in all System 7 games, Black Knight (Dec '80) and later. Note that in some games like (at least) Black Knight and Jungle Lord, the factory labels on the flipper ROMs are incorrect. The labels on IC17 and IC20 are swapped as shown in the image at right.
*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===
[[File:MolexExample.jpg|300px|thumb|left|Molex Connectors used in Williams System 3-7 games]] 
* [[Media: Molex-Connectors-Firepower-1.1.pdf|Molex connectors used in Williams System 3-7 games]]
 

===Displays===
[[File:WMS3-7MasterDisplayBoard.jpg|300px|thumb|left|Williams System 3-6 master display board layout]] 
* [[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:Wms-sys3-mpu-layout.jpg ‎|left|thumb|300px|Board Layout Diagrams and Schematics]]
* [[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]]
 
[[File:S7Schematics.jpg ‎|left|thumb|300px|System 7 MPU Board Schematics]] 
* [[Media:Sys7-cpu-logic2.pdf|System 7 MPU Board Schematics]]
 

===Power Supply===
[[File:WMS3-7PowerSupplies.jpg|300px|thumb|left|Williams System 3-7 Power Supply board layout]] 
* [[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 Schematic]]

* [[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 Schematic]]

* [[Media:WMSSystem7PSDrawing.jpg ‎|System 7 Power Supply Board Assembly Drawing]]
* [[Media:WMSSystem7PSSchematic.png ‎|System 7 Power Supply Board Schematic]]
 

===Sound Board===

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

====Type 1 Sound Board====
[[File:WMS3-4RectangularSoundBoard.jpg|300px|thumb|left|Williams Rectangular Sound board layout]] 
[[Media:WMS_Sys3-6_Type_1_Sound Board.pdf|System 3-4 Type 1 Sound Board Assembly Drawing and Schematic]]
 

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

All of the following were crafted by Phil Butcher and Richard Harvey. Thanks gents! 
[[File:WMS6-7SquareSoundBoard.jpg|300px|thumb|left|Williams Square Sound board layout]] 
[[Media:Wms-sys6-7-soundspeech-assembly.pdf|System 6-7 Sound & Speech Boards Assembly Drawing]] 

[[Media:18-soundlogic.pdf | System 6-7 Sound Board Schematics]] 
[[Media: Speech-Logic-8226.pdf | System 6-7 Model 8226 Speech Board Schematics]] 
[[Media: Speech-Logic-8228.pdf | System 6-7 Model 8228 Speech Board Schematics]] 
 

==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 Williams IC chips are marked with proprietary Williams part numbers. 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 relay to control general illumination
* An improved 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. The remaining System 3 games and in all System 4 games, the sound board was located in the cabinet.

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

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

==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. 

==MPU Boards==

===System 3===
[[File:WMS sys3 MPU board.JPG|thumb|left|300px|Williams System 3 MPU Board]]
[[File:WilliamsSystem3MPURevisionA.jpg ‎|right|thumb|300px|System 3 MPU IC Locator. The System 4 MPU adds only IC26 on the left side of the board, just above IC22 where the odd looking solder pads are.
]] 
System 3 was a major step by Williams to digital pinball games. System 3 ushered in Solid State machines but there were problems with the acceptance of the new machines.

Williams used the driver board to drive solenoids on chime units 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 could still be found on location. Player scoring, credits remaining and the ball-in-play were all digitally displayed on high voltage seven-segment gas plasma displays.

Even after Williams removed chimes and 'noisemakers' (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 through System 7 sound boards. Operators rarely used this feature. Digital sound became more popular and soon gained greater player acceptance. 

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 board was used to drive the displays. All other peripherals, switches, lamps, solenoids, and sound, were 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 can use either a 6802 or 6808 microprocessor. A 6802 or 6808 can not be used in a System 3 or 4 board.
 

====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. This capacitor is located just below the 5101 RAM]] 
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, retaining the 6800 microprocessor. 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:WMSSystem6AMPU.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 34 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 (found [https://www.pinwiki.com/wiki/index.php/File:FPCOMBO.zip here]) 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 (Somewhere Between 6 and 7)===
[[File:WilliamsSystem679OddballMPU.jpg|thumb|left|300px|Williams System (unknown) MPU Board. Image courtesy of Jerry Clause]]
The MPU board pictured at left was installed in a working Williams BlackOut game. At this time, there is no information available about this board.
 

===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]]
 
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]]
[[File:WMSSystem6PSSchematic.jpg|thumb|300px|right|Williams System 3-6 Power Supply Schematic]] 
Power Supply Part Number: D-7999 
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.

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 when installed in later games. 

[[File:WMSSystem7PowerSupply.jpg|thumb|300px|left|Williams System 7 Power Supply (GI input connector modified from stock)]]
[[File:WMSSystem7PSSchematic.png|thumb|300px|right|Williams System 7 Power Supply Schematic]] 
Power Supply Part Number: D-8345 
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 with a vertical 12,000uf cap should have these jumpers. Type 1 sound boards with a horizontal 12,000uf cap do not require these jumpers as the modification they make has been picked up in the board silkscreen. Note: These factory installed jumpers take advantage of trace "vias" to accomplish these connections and removal of one tantalum cap.

#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 additional 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===
<gallery widths=400px heights=400px perrow=2 caption="Williams System 6-7 Type 2 Sound and Speech Boards">
File:JoustType2SoundBoard.jpg ‎|Williams System 6-7 Type 2 Sound Board. Note that the board pictured is jumpered for Williams Joust head-to-head pinball
File:HyperballType2SoundBoard.jpg ‎ ‎|Williams System 6-7 Type 2 Sound Board. Note that the board pictured is jumpered for Williams HyperBall
File:WMS Sys6-7 sound speech.JPG|Williams System 6-7 Type 2 Sound Board with Speech Board Connection. The board pictured is jumpered for games without speech. Removing the jumper at W1 would configure the board for games with a speech board. W1 is located just under the cut key pin on the top left connector. W1 is oriented horizontally
File:WilliamsType2SoundAndSpeechBoarfPair.jpg ‎|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.
</gallery>
 

====Type II Sound Board Jumpers====
Jumpers for each game are as follows:
*W2,5,7,9,10,15 - Gorgar, Blackout, Firepower, Black Knight, Jungle Lord, Pharaoh (games with a speech card).
*W1,2,5,7,9,10,15 - Defender, Solar Fire, Barracora, Stargate, Cosmic Gunfight, Varkon, Time Fantasy (games without a speech card).
*W1,3,5,7,10,14,15 - Hyperball
*W1,3,4,5,7,10,15 - Joust (Note that the jumpers listed here are different than listed on the schematic diagram. However, these jumpers have been verified as correct).

==Speakers==
With the exception of Hot Tip and Lucky 7, all Williams System 3-7 games use a single 6-1/2" speaker located on the cabinet. Some later games, like Firepower II, employed an elliptical speaker below the backglass instead). All speakers used were rated at 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 High Voltage Drive Transistors]]
[[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]]
 

==Drop Target Banks==
===First Generation Drop Target Bank===
[[File:WMS Horseshoe Drops.JPG|300px|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|300px|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|300px|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|300px|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|300px|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=

==Add Fuses Between the Transformer Secondary and Backbox Bridge Rectifiers==
[[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>
 

[[File:WMSSystem6ButtonBattery.jpg ‎|300px|thumb|left|Williams System 6 MPU Coin Cell Installation]] 
Coin cell installation on a System 6 MPU board is slightly different physically but exactly the same electrically.
 

[[File:System7CoinCellBatteryHolder.png ‎|300px|thumb|left|Williams System 7 MPU Coin Cell Installation]] 
Coin cell installation on a System 7 MPU board is slightly different physically but exactly the same electrically.
 

===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]]
[[File:WMSDiagSwitch.jpg|300px|thumb|Right|The internals of the diagnostic switches. These are single pole, double throw switches spring loaded to close one side of the switch]]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.

System 3 games require the diagnostic button (lower button) to be pressed to start diagnostics. Once that button is pressed, navigating through the diagnostic menu is identical to later game systems (see below).
 

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.

[[File:YT.png]] A video demonstrating System 6 and 7 game diagnostic entry can be found [https://youtube.com/shorts/9BEh5Qn_sWA here].
 

== 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>Replace all headers. Reflowing solder does not create a solid mechanical or electrical connection.</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. In practice, these chips don't fail due to the high temperature environment.</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==
[[file:WMSSystem3-6PowerSupply.jpg ‎|400px|thumb|left|Williams System 3-6 Power Supply Schematic]]
The power supply board (PSB) combines serval power circuits on the same board. They don't interact, and are:
* +18V for Lamps
* +28V Solenoids (and Flippers)
* Regulated +5V for digital logic and an unregulated +12v for CPU reset
* +/- 100VDC HV supply for the Displays.
* General Illumination (GI). Note: starting with System 7 games, the GI circuit added a relay, making GI power switchable under game software control.

Input AC power is supplied 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===
[[file:WMSLampPowerCapacitor.jpg ‎|300px|thumb|left|A typical 18,000uf/25V lamp power filter capacitor. These caps almost never require replacement]]
* The +18VDC Lamp voltage is filtered by a very large 'blue can' capacitor between the BR and the PSU board.
** 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.
 

===Solenoid Power===
The solenoid power circuit is shown below.

[[File:WMSSystem3-7PowerSupplySolenoidCircuit.jpg|1000px|thumb|left|A snippet of the 28VDC solenoid power circuit.]] 

C13 (100uf) and C14 (.1uf) remove residual noise from the DC power. 
VR1, a Metal Oxide Varistor acts as a surge suppresser. It is designed to blow (shorted) which will cause a fuse to blow. 
F2, a 2 1/2ASB fuse protects the solenoid power circuit should a solenoid become "locked on" for an extended period of time. 
Other than these additional components, the circuit is pretty simple.
 

===Flipper Power===
Flipper power is routed through the power supply for the sole purpose of protecting the circuit with either a 10 (2 flippers) or 15 (3 or 4 flippers) amp slo-blo fuse.

Flipper power is then routed to connector 3J3 pins 4 and 5.

===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 the 5V regulator (labeled X3) which is an LM323K or 75H05. Note that an ezSBC 5V regulator is a "drop in" replacement for the OEM 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.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 (replace with MJE15030, must cross legs) and SDS-202 (replace with MJE15031, must cross legs) 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 Zener diodes, at locations Z2 & Z4 to reduce the Display output to about+/-90v under load and extend display life.
* Repin of Headers at 3J1 and the used pins at 3J2, theory for using crimped TriFurcon 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. Note that ZR1 has not yet been removed in this image]] 
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).
 

[[File:System6ResetMod.png|left|thumb|300px|Williams System 6 MPU board stock reset circuit, annotated]] 
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. 

[[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
#Optionally, 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 jumper between the top pad of R42 and the "C" collector pad (top pad) where Q6 was installed (orange highlighted area in pic).
#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)
#Optionally, 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.

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. 

[[File:Wms drvr interconnect.JPG|left|thumb|300px|The 40 pin female connector on the driver board]]
Next, 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].
 

===Every-Other Digit Dim On All Displays===
[[File:EveryOtherDigitDim.jpg ‎|thumb|left|300px|Half of the digits, or every-other digit, are dimly displayed. This behavior was caused by a failed 4020 IC25.]] 
This rare failure is caused by the 4020 at IC25 (on a System 7 MPU) failing such that either pin 12, 13, or 14 is "dead". In this case, display interrupts occur too rapidly, and the 6800/6802 can't service those interrupts quickly enough to properly render display data.

[[File:YT.png]] A YouTube video demonstrating this failure, and the correction, can be found [https://youtu.be/_qOhzzwpbu0 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.

[[image:YT.png]] 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.

===Type II Sound Board Jumpers===
The following jumpers are installed for these games.
*W2,5,7,9,10,15 - Gorgar, Blackout, Firepower, Black Knight, Jungle Lord, Pharaoh (games with a speech card).
*W1,2,5,7,9,10,15 - Defender, Solar Fire, Barracora, Stargate, Cosmic Gunfight, Varkon, Time Fantasy (games without a speech card).
*W1,3,5,7,10,14,15 - Hyperball
*W1,3,4,5,7,10,15 - Joust (Note that the jumpers listed here are different than listed on the schematic diagram. However, these jumpers have been verified as correct).

===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.
[[File:SoundCardBR.jpg|300px|thumb|right|Loss of +12 or -12VDC could be caused by a failed bridge rectifier]]
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.

Another means to address noisy type 1 sound boards is nicely outlined "The Williams Guy" on YouTube. 
[[image:YT.png]] His YouTube video explaining these modifications can be found [https://www.youtube.com/watch?v=ENlTnL5Qgac here]. 

===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.

{| class="wikitable" 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:

{| class="wikitable" 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:

{| class="wikitable" 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:

{| class="wikitable" 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.

{| class="wikitable" bordercolor="#0" cellspacing="0" cellpadding="3" width="10%" border=2 style="text-align: center;"
|+'''DS1 Set correctly for Sounds and Speech'''
| SW 2
| ON
|-
| SW 1
| OFF
|}

 

{| class="wikitable" bordercolor="#0" cellspacing="0" cellpadding="3" width="10%" border=2 style="text-align: center;"
|+'''DS1 Set for Sounds only'''
| SW 2
| OFF
|-
| SW 1
| OFF
|}

You will also have to '''jumper W1''' if this is not in place.
 

===Excessive Hum from Type 1 Sound Boards===
A possible solution for excessive hum from the Type 1, rectangular, sound boards is discussed on PinSide, [https://pinside.com/pinball/forum/topic/williams-flash-speaker-hum#post-8637841 here].
 

==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. 

These days one or two of the MC1458 chips on the speech board go bad too frequently. This results usually in either no sound and/or missing speech. These should be replaced in any case while you are on it. Use good quality machine pin sockets when replacing. 

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].

[[image:YT.png]] A video of Leon's ROM working correctly in a Williams Sound and Speech Board pair can be found [https://youtu.be/NYG7AK0G838?si=Js-n_WkNQSONwS-X 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. A 2716 ROM can be used. Or a 2732 ROM can be used by doubling the image.

Here's a key tip: Divide and conquer. Install jumper W1, set SW1 and SW2 to OFF, and '''test without the speech board''' until sounds are working 100%.

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.

'''Game and Sound ROM checksums''' can be found [https://web.archive.org/web/20141208121800/http://pin-logic.com/early_williams_pinball_game.htm pinball here], originally published at Tom Callahan's pinlogic.com.

{| class="wikitable" cellspacing="0" cellpadding="3" width="50%" border="2"
|+ '''Williams Pinball Machines that use a Type 2 Sound Board and a Speech Board'''
!Name
!Sys
!Game
!WMS Sound ROM
|-
| Blackout
| <center>6</center>
| <center>495</center>
| Sound ROM 2
|-
| Gorgar
| <center>6</center>
| <center>496</center>
| Sound ROM 2
|-
| Firepower
| <center>6</center>
| <center>497</center>
| Sound ROM 3
|-
| Black Knight
| <center>7</center>
| <center>500</center>
| Sound ROM 5
|-
| Alien Poker
| <center>6A</center>
| <center>501</center>
| Sound ROM 3 confirmed
|-
| Jungle Lord
| <center>7</center>
| <center>503</center>
| Sound ROM 3
|-
| Pharoah
| <center>7</center>
| <center>504</center>
| Sound ROM 6
|}

One Williams video game used the Sound and Speech Board, Sinistar (cockpit front) and Upright VIDEO ROM 9

{| class="wikitable" cellspacing="0" cellpadding="3" width="60%" align="left" border="2"
|+ '''Williams Pinball Machines that use Sound Boards Only'''
!Name
!Sys
!Game
!WMS Board, Sound ROM
|-
|Flash
|<center>4</center>
|<center>486</center>
|Type 1 Board, ROM 1
|-
|Time Warp
|<center>6</center>
|<center>489</center>
|Type 1 Board, ROM 1
|-
|Stellar Wars
|<center>4</center>
|<center>490</center>
|Type 1 Board, ROM 1
|-
|Laser Ball
|<center>6</center>
|<center>493</center>
|Type 1 Board, ROM 2
|-
|Scorpion
|<center>6</center>
|<center>494</center>
|Type 1 Board, ROM 1
|-
|Algar
|<center>6A</center>
|<center>499</center>
|Type 1 Board, ROM 4
|-
|Cosmic Gunfight
|<center>7</center>
|<center>502</center>
|Type 2 Board, ROM 12
|-
|Solar Fire
|<center>7</center>
|<center>507</center>
|Type 2 Board,ROM 7
|-
|Hyperball (n)
|<center>7</center>
|<center>509</center>
|Type 2 Board, SPECIAL ROM 8?
|-
|Barracora
|<center>7</center>
|<center>510</center>
|Type 2 Board,ROM 4
|-
|Time Fantasy
|<center>7</center>
|<center>515</center>
|Type 2 Board,ROM 13
|-
|Warlock (pin)
|<center>7</center>
|<center>516</center>
|Type 2 Board,ROM 14
|-
|Defender (pin)
|<center>7</center>
|<center>517</center>
|Type 2 Board,ROM 15
|-
|Joust (2 player head to head)
|<center>7</center>
|<center>519</center>
|Type 2 Board,SPECIAL Snd_IC12.532 ROM
|-
|Laser Cue
|<center>7</center>
|<center>520</center>
|Type 2 Board,ROM 3
|-
|Firepower II
|<center>7</center>
|<center>521</center>
|Type 2 Board,ROM 13
|-
|Star Light *
|<center>7</center>
|<center>530</center>
|Type 2 Board, ROM 3 ROM 4 has been found in at least one game
|}
 
(n) Not a Pinball, a shooter game that shoots 1/2" balls. Similar to Bally's [https://www.ipdb.org/machine.cgi?id=3568 Rapid Fire].

* Quite a rare and beautiful pinball. Only 100 were produced, the last Williams System 7.

{| class="wikitable" 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 (2 player head to head) 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. In this example, IC stands for Integrated Circuit, and the 12 is the chip number (U12) found on the board. The file extension indicates the type and size of the EPROM (a 2'''716''', in this case).

===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.
 

====Theory of operation====

The trigger switch is connected to ground on one side. It is connected to 5V on the other side via a 4.7Kohm pullup resistor and also connected to one of the 4 NOR gate inputs of a 74LS02 IC. This holds the input of the 74LS02 at logic high until the switch is closed and thereby shorted to ground, changing the logic state to low.

A 74LS02 is a quad NOR gate. NOR gates require both inputs of the NOR gate to be logic low (0) for the output to yield logic high (1). If either of the 2 inputs to the NOR gate are high, the NOR gate output is low. For example, if input pins 11 and pin 12 are both low (logic "0"), then output pin 13 will be high (logic "1"). If either input pin 11 or 12 is at logic high, then output pin 13 will be low (logic "0").

This implementation allows the CPU to "disable" the special solenoids by simply holding one NOR input high, rendering the output low (logic "0") regardless of the switch being closed or not. The output from the 74LS02 drives a 2N4401 pre-driver transistor which is used to switch the TIP-122 (a TIP-102 or BDX-53C can be substituted) drive transistor on, and hence proved a path to ground for coil power and energizing the coil.
 

====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, then 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 ||Right PIA on Driver Board
|-
|4 ||II ||IC11 SW Matrix ||39 ||Right PIA on Driver Board
|-
|5 ||IV ||IC 5 Solenoids ||39 ||Left 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 ||7406(S) / 74LS06
|-
|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, now called W9-W16]]
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 W9-W16, 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 naphtha 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]
** [https://www.wolffpactech.com/product-page/williams-system-3-6-display-kit Wolffpac 6-Digit] (ships as a kit)
** [https://www.wolffpactech.com/product-page/williams-system-7-9-display-kit-orange-digits Wolffpac 7-Digit] (ships as a kit)
* MPU/Driver Combo
** [http://www.rottendog.us/?product=mpu327 Rottendog] (no longer supports System 7 games)
** [https://nvram.weebly.com/wms-3-7.html barakandl] (supports System 7)
* 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.

==Game will not come out of audit mode==
If a System 3-6 MPU will not come out of audit mode despite a quick power cycle with the coin door open, suspect a bad 5101 RAM. This probably also applies to System 7 MPUs but have not verified.

==Controlled lamps issue==
Problem: (System 6 Flash) In attract (game over) mode the controlled lights were lit most of the time, just kind of flickering. But, they all worked during lamp test mode and would all turn on and off at the same time.

Cause: The 5V regulator on the power supply board had failed and sent 12VDC to all of the boards. Part "X3", LM323K

Solution: Replaced the 5V regulator. Had to then replace these parts on the solenoid driver board: IC10 (PIA, 6821), IC12 & IC19 (7406), IC13 & IC14 (7408).
Note: 12VDC on the 5V line could potentially cause any chip to fail that uses the 5V.

American Pinball Repair Guides

2026-03-10T01:57:02Z

Diz: /* Games */

''For history of American Pinball see [[American Pinball]].''

{{WIP}}

== Introduction ==

Manufacturer's website: https://www.american-pinball.com/

American Pinball, Inc.
1448 Yorkshire Drive
Streamwood, ILL. 60107
Telephone: (847) 893-6800
info@american-pinball.com

== Games ==
{| class="wikitable"
!Title
!Date of Release
!Model #
!Notes
|-
|[[Houdini]] || 12-2017 || ||
|-
|Oktoberfest || 03-2019 || ||
|-
|Hot Wheels || 06-2020 || ||
|-
|Legends of Valhalla || 10-2021 || ||
|-
|Galactic Tank Force || 2023 || ||
|-
|Barry O's BBQ Challenge || 2024 || ||
|-
|}

== Technical Info ==

=== Game Code Updates ===

Game code updates can be downloaded here: https://www.american-pinball.com/support/updates/

There is a USB jack located near the service outlet in which a thumb drive loaded with the update can be plugged in.

=== Manuals ===

* Oktoberfest Game Manual: http://s4.american-pinball.com/img/support/2019-7/Oktoberfest-Manual-new.pdf

* Oktoberfest Assemblies Manual: http://s4.american-pinball.com/img/support/2019-7/Assembly.pdf

* Houdini Game Manual: http://s4.american-pinball.com/img/support/2018-10/AP_Houdini-Service-Manual_091018.pdf

* Hot Wheels Game Manual: http://s4.american-pinball.com/img/support/2020-7/Hot-Wheels-Manual-7-13-2020.pdf

* Legends of Valhalla Game Manual: http://s4.american-pinball.com/img/support/2022-3/Rampage-Manual-10-19-2021.pdf

* Galactic Tank Force Game Manual: http://s4.american-pinball.com/img/support/2023-11/Galactic-Tank-Force-Game-Manual-(Version-1.0_October-2023).pdf

* Barry O's BBQ Challenge Game Manual: http://s4.american-pinball.com/img/support/2024-6/Barry-O's-BBQ-Challenge-Game-Manual_English_Production-Release-1.0_June-2024.pdf

=== Boards ===

The "Add On Board" (PCB0021-01) on Houdini controls the Start Button LED (12 volts), Shaker Motor (12 volts), and Knocker Coil (48 volts). It can control a maximum of 7 devices.

American Pinball uses the MultiMorphic board sets.

* P3-ROC CPU (PCB0002-00)
* SW-16 board
* PD-16 board (PCB0004-00)
* PD-LED2 board (PCB0008-00)

=== Power Supplies ===

The power supply which operates the coils is a Mean Well model RSP-750-48 (48 volts @ 15 amps, 750 watts). Jameco Electronics has it as their stock number 2172148. Some machines may have a Velika (www.best-force.com) model S-800-48 (48v @ 16.7 amps) power supply installed.

=== Displays ===

Main monitor in backbox is 15.6" Monitor Assembly # MASM0026-00. It is an Astouch model A156-OPD01 which operates on 12 volts DC @ 4 amps. The Stage Monitor is 4.3" screen size.

[[File:Houdini_Astouch_monitor.JPG|200px|thumb|left|Astouch monitor in a Houdini]] 

 

=== Speakers ===

Houdini uses the following speakers:

*(2) midbass 4" backbox speakers # ELE005-00
*(2) midbass 3" backbox speakers # ELE004-00
*(2) tweeters 2" backbox speakers # ELE0003-00

There is no woofer speaker in the bottom cabinet of Houdini.

[[File:Houdini_no_woofer.JPG|200px|thumb|left|Houdini does not have a woofer]] 

 

=== Flippers ===

Houdini uses Williams WPC style flipper assemblies. The flipper coil is a lugless type with a connector already on it so no soldering is needed. Just plug/unplug the coil. American Pinball coil # COL0003-00. End of stroke switches are normally open when the flipper is at rest and closes when the flipper is energized.

=== Cabinet Parts ===

Ball shooter assembly is the common Williams shooter housing and sleeve combo, but the housing is powder coated to match the game it's installed on. Coin door is a Happ Controls door with the four pushbutton switches much like a Stern Spike system door. Caution note: Houdini uses 12 volt dc coin door LED bulbs. Power switch and service outlet are in the normal locations.

[[File:Houdini_menu_buttons.JPG|200px|thumb|left|Coin door diagnostic/menu buttons]] 

 

== Problems and Solutions ==

=== Power Supplies ===

[[File:Houdini_48v_power_supply.JPG|200px|thumb|left|Houdini 48 volt power supply]]
[[File:Houdini_service_outlet.JPG|200px|thumb|center|Houdini service outlet and power switch]] 

 

=== Solenoid Problems ===

Coil driver transistors are type IRL540N (N channel FET).

=== Switch Problems ===

=== Lamp Problems ===

==== General Illumination Problems ====

==== Controlled Lamp Problems ====

=== Display Problems ===

=== Sound Problems ===

Houdini uses a Lepy model LP-168S or Lepai LP-168HA (sold by Parts Express) super bass power amplifier. Specs are 2 X 40 watt amplifier and 1 X 68 watt subwoofer output. Owner's manual for the LP-168HA is located here:
https://lepaiaudio.com/docs/manuals/310-308--lp-168ha-manual.pdf

The Lepy LP-168S is a knockoff (counterfeit) of the Lepai LP-168HA:

https://lepaiaudio.com/counterfeit/

[[File:Houdini_Lepy_LP168S_amplifier.JPG|200px|thumb|left|Lepy LP-168S amplifier]] 

 

=== Flipper Problems ===

Williams WPC style flipper assemblies. End of stroke switches are normally open when the flipper is at rest.

A common problem is the flipper gets stuck in the up position. This can be due to a broken flipper return spring.

https://store.american-pinball.com/products/houdini-flipper-spring-set

=== Pop Bumper Problems ===

Houdini uses the black color Data East/Sega pop bumper assemblies.

== Optional Equipment ==

These are some of the optional accessory equipment available for American Pinball machines.

* Shaker Motor Kit # KIT0001-00 (plugs into "Add On Board" )
* Knocker Kit # KIT0002-00 (adds a real knocker, plugs into "Add On Board" )
* Add On Driver Board # PCB0021-01 (allows connection of accessory items such as shaker motor and knocker)
* End Of Stroke Switch Kit # KIT0004-00 (for Houdini flippers, corrects flipper problems)
* Houdini Power Supply Upgrade # MASM0132-00 (Houdini only, operates coils better than original power supply)
* Houdini Topper # MASM0071-00 (includes ac power adapter)

==== Bill Acceptors ====

* Houdini comes factory pre-wired for 120 volt AC power Mars bill acceptors.

* Oktoberfest comes factory pre-wired for 12 volt DC bill acceptors. Use ICT model A6-25SCP-USD4-II.

== Game Specific Problems and Fixes ==

Houdini weak or erratic odd feeling flippers: Early production Houdini machines did not have End-of-Stroke switches on the flipper assemblies. Order Kit # KIT0004-00 End Of Stroke switch kit.
https://store.american-pinball.com/collections/all/products/houdini-end-of-stroke-switch 

Houdini coils are weak: Early production Houdini machines need an additional 48 volt power supply for the coils. Order kit # MASM0132-00 Power Supply Upgrade Kit:
https://store.american-pinball.com/products/houdini-power-supply-upgrade
Also install Houdini Coil Performance Improvement Kit # KIT0006-00

=== Service Bulletins ===

* Houdini Scoop Adjustment: http://s4.american-pinball.com/img/support/2018-6/SCOOP-ADJUSTMENT.pdf

* Houdini Coil Performance Improvement Kit: http://s4.american-pinball.com/img/support/2020-8/Houdini--Coil-Performance-Improvement-Kit.pdf

* Houdini Dollar Bill Acceptor Fix: http://s4.american-pinball.com/img/support/2021-6/12v-DC-and-120v-AC-Dollar-Bill-Acceptor-connector.pdf

* Houdini Skill Shot Fix: http://s4.american-pinball.com/img/support/2018-5/Houdini-Skill-Shot-Fix.pdf

* Houdini Speaker Grill Installation: http://s4.american-pinball.com/img/support/2018-6/Speaker-Grill-Installation.pdf

* Houdini Stage Door Servo Installation: http://s4.american-pinball.com/img/support/2019-9/Stage-Door-Servo-Installation.pdf

* Houdini "Add On Board" (for connecting accessories): http://s4.american-pinball.com/img/support/2018-9/Add-On-Board.pdf

* Houdini EOS Installation (flippers): http://s4.american-pinball.com/img/support/2019-10/End-Of-Stroke-Switch.pdf

* Houdini Knocker Installation: http://s4.american-pinball.com/img/support/2019-9/Knocker-Installation.pdf

* Houdini Power Supply Kit (48 volts): http://s4.american-pinball.com/img/support/2018-10/Power-Supply-Kit-Installation.pdf

* Houdini Shaker Motor Installation: http://s4.american-pinball.com/img/support/2018-6/Shaker.pdf

* Oktoberfest Knocker Kit Installation: http://s4.american-pinball.com/img/support/2019-5/Knocker-Installation.pdf

* Oktoberfest Power Distribution Wiring: http://s4.american-pinball.com/img/support/2018-10/Power-Distribution.pdf

* Oktoberfest Shaker Motor Installation: http://s4.american-pinball.com/img/support/2019-9/Oktoberfest-Shaker-Installation.pdf

* Oktoberfest Bar Door Not Working: http://s4.american-pinball.com/img/support/2019-7/Bar-Door-Check.pdf

* Oktoberfest Dollar Bill Acceptor Installation: http://s4.american-pinball.com/img/support/2019-6/Wire-Diagram-DBA.pdf

* Oktoberfest Add On Board Wiring: http://s4.american-pinball.com/img/support/2019-5/New-Add-On-Board.pdf

American Pinball Repair Guides

2026-03-10T01:54:03Z

Diz: /* Technical Info */

''For history of American Pinball see [[American Pinball]].''

{{WIP}}

== Introduction ==

Manufacturer's website: https://www.american-pinball.com/

American Pinball, Inc.
1448 Yorkshire Drive
Streamwood, ILL. 60107
Telephone: (847) 893-6800
info@american-pinball.com

== Games ==
{| class="wikitable"
!Title
!Date of Release
!Model #
!Notes
|-
|[[Houdini]] || 12-2017 || ||
|-
|Oktoberfest || 03-2019 || ||
|-
|Hot Wheels || 06-2020 || ||
|-
|Legends of Valhalla || 10-2021 || ||
|-
|}

== Technical Info ==

=== Game Code Updates ===

Game code updates can be downloaded here: https://www.american-pinball.com/support/updates/

There is a USB jack located near the service outlet in which a thumb drive loaded with the update can be plugged in.

=== Manuals ===

* Oktoberfest Game Manual: http://s4.american-pinball.com/img/support/2019-7/Oktoberfest-Manual-new.pdf

* Oktoberfest Assemblies Manual: http://s4.american-pinball.com/img/support/2019-7/Assembly.pdf

* Houdini Game Manual: http://s4.american-pinball.com/img/support/2018-10/AP_Houdini-Service-Manual_091018.pdf

* Hot Wheels Game Manual: http://s4.american-pinball.com/img/support/2020-7/Hot-Wheels-Manual-7-13-2020.pdf

* Legends of Valhalla Game Manual: http://s4.american-pinball.com/img/support/2022-3/Rampage-Manual-10-19-2021.pdf

* Galactic Tank Force Game Manual: http://s4.american-pinball.com/img/support/2023-11/Galactic-Tank-Force-Game-Manual-(Version-1.0_October-2023).pdf

* Barry O's BBQ Challenge Game Manual: http://s4.american-pinball.com/img/support/2024-6/Barry-O's-BBQ-Challenge-Game-Manual_English_Production-Release-1.0_June-2024.pdf

=== Boards ===

The "Add On Board" (PCB0021-01) on Houdini controls the Start Button LED (12 volts), Shaker Motor (12 volts), and Knocker Coil (48 volts). It can control a maximum of 7 devices.

American Pinball uses the MultiMorphic board sets.

* P3-ROC CPU (PCB0002-00)
* SW-16 board
* PD-16 board (PCB0004-00)
* PD-LED2 board (PCB0008-00)

=== Power Supplies ===

The power supply which operates the coils is a Mean Well model RSP-750-48 (48 volts @ 15 amps, 750 watts). Jameco Electronics has it as their stock number 2172148. Some machines may have a Velika (www.best-force.com) model S-800-48 (48v @ 16.7 amps) power supply installed.

=== Displays ===

Main monitor in backbox is 15.6" Monitor Assembly # MASM0026-00. It is an Astouch model A156-OPD01 which operates on 12 volts DC @ 4 amps. The Stage Monitor is 4.3" screen size.

[[File:Houdini_Astouch_monitor.JPG|200px|thumb|left|Astouch monitor in a Houdini]] 

 

=== Speakers ===

Houdini uses the following speakers:

*(2) midbass 4" backbox speakers # ELE005-00
*(2) midbass 3" backbox speakers # ELE004-00
*(2) tweeters 2" backbox speakers # ELE0003-00

There is no woofer speaker in the bottom cabinet of Houdini.

[[File:Houdini_no_woofer.JPG|200px|thumb|left|Houdini does not have a woofer]] 

 

=== Flippers ===

Houdini uses Williams WPC style flipper assemblies. The flipper coil is a lugless type with a connector already on it so no soldering is needed. Just plug/unplug the coil. American Pinball coil # COL0003-00. End of stroke switches are normally open when the flipper is at rest and closes when the flipper is energized.

=== Cabinet Parts ===

Ball shooter assembly is the common Williams shooter housing and sleeve combo, but the housing is powder coated to match the game it's installed on. Coin door is a Happ Controls door with the four pushbutton switches much like a Stern Spike system door. Caution note: Houdini uses 12 volt dc coin door LED bulbs. Power switch and service outlet are in the normal locations.

[[File:Houdini_menu_buttons.JPG|200px|thumb|left|Coin door diagnostic/menu buttons]] 

 

== Problems and Solutions ==

=== Power Supplies ===

[[File:Houdini_48v_power_supply.JPG|200px|thumb|left|Houdini 48 volt power supply]]
[[File:Houdini_service_outlet.JPG|200px|thumb|center|Houdini service outlet and power switch]] 

 

=== Solenoid Problems ===

Coil driver transistors are type IRL540N (N channel FET).

=== Switch Problems ===

=== Lamp Problems ===

==== General Illumination Problems ====

==== Controlled Lamp Problems ====

=== Display Problems ===

=== Sound Problems ===

Houdini uses a Lepy model LP-168S or Lepai LP-168HA (sold by Parts Express) super bass power amplifier. Specs are 2 X 40 watt amplifier and 1 X 68 watt subwoofer output. Owner's manual for the LP-168HA is located here:
https://lepaiaudio.com/docs/manuals/310-308--lp-168ha-manual.pdf

The Lepy LP-168S is a knockoff (counterfeit) of the Lepai LP-168HA:

https://lepaiaudio.com/counterfeit/

[[File:Houdini_Lepy_LP168S_amplifier.JPG|200px|thumb|left|Lepy LP-168S amplifier]] 

 

=== Flipper Problems ===

Williams WPC style flipper assemblies. End of stroke switches are normally open when the flipper is at rest.

A common problem is the flipper gets stuck in the up position. This can be due to a broken flipper return spring.

https://store.american-pinball.com/products/houdini-flipper-spring-set

=== Pop Bumper Problems ===

Houdini uses the black color Data East/Sega pop bumper assemblies.

== Optional Equipment ==

These are some of the optional accessory equipment available for American Pinball machines.

* Shaker Motor Kit # KIT0001-00 (plugs into "Add On Board" )
* Knocker Kit # KIT0002-00 (adds a real knocker, plugs into "Add On Board" )
* Add On Driver Board # PCB0021-01 (allows connection of accessory items such as shaker motor and knocker)
* End Of Stroke Switch Kit # KIT0004-00 (for Houdini flippers, corrects flipper problems)
* Houdini Power Supply Upgrade # MASM0132-00 (Houdini only, operates coils better than original power supply)
* Houdini Topper # MASM0071-00 (includes ac power adapter)

==== Bill Acceptors ====

* Houdini comes factory pre-wired for 120 volt AC power Mars bill acceptors.

* Oktoberfest comes factory pre-wired for 12 volt DC bill acceptors. Use ICT model A6-25SCP-USD4-II.

== Game Specific Problems and Fixes ==

Houdini weak or erratic odd feeling flippers: Early production Houdini machines did not have End-of-Stroke switches on the flipper assemblies. Order Kit # KIT0004-00 End Of Stroke switch kit.
https://store.american-pinball.com/collections/all/products/houdini-end-of-stroke-switch 

Houdini coils are weak: Early production Houdini machines need an additional 48 volt power supply for the coils. Order kit # MASM0132-00 Power Supply Upgrade Kit:
https://store.american-pinball.com/products/houdini-power-supply-upgrade
Also install Houdini Coil Performance Improvement Kit # KIT0006-00

=== Service Bulletins ===

* Houdini Scoop Adjustment: http://s4.american-pinball.com/img/support/2018-6/SCOOP-ADJUSTMENT.pdf

* Houdini Coil Performance Improvement Kit: http://s4.american-pinball.com/img/support/2020-8/Houdini--Coil-Performance-Improvement-Kit.pdf

* Houdini Dollar Bill Acceptor Fix: http://s4.american-pinball.com/img/support/2021-6/12v-DC-and-120v-AC-Dollar-Bill-Acceptor-connector.pdf

* Houdini Skill Shot Fix: http://s4.american-pinball.com/img/support/2018-5/Houdini-Skill-Shot-Fix.pdf

* Houdini Speaker Grill Installation: http://s4.american-pinball.com/img/support/2018-6/Speaker-Grill-Installation.pdf

* Houdini Stage Door Servo Installation: http://s4.american-pinball.com/img/support/2019-9/Stage-Door-Servo-Installation.pdf

* Houdini "Add On Board" (for connecting accessories): http://s4.american-pinball.com/img/support/2018-9/Add-On-Board.pdf

* Houdini EOS Installation (flippers): http://s4.american-pinball.com/img/support/2019-10/End-Of-Stroke-Switch.pdf

* Houdini Knocker Installation: http://s4.american-pinball.com/img/support/2019-9/Knocker-Installation.pdf

* Houdini Power Supply Kit (48 volts): http://s4.american-pinball.com/img/support/2018-10/Power-Supply-Kit-Installation.pdf

* Houdini Shaker Motor Installation: http://s4.american-pinball.com/img/support/2018-6/Shaker.pdf

* Oktoberfest Knocker Kit Installation: http://s4.american-pinball.com/img/support/2019-5/Knocker-Installation.pdf

* Oktoberfest Power Distribution Wiring: http://s4.american-pinball.com/img/support/2018-10/Power-Distribution.pdf

* Oktoberfest Shaker Motor Installation: http://s4.american-pinball.com/img/support/2019-9/Oktoberfest-Shaker-Installation.pdf

* Oktoberfest Bar Door Not Working: http://s4.american-pinball.com/img/support/2019-7/Bar-Door-Check.pdf

* Oktoberfest Dollar Bill Acceptor Installation: http://s4.american-pinball.com/img/support/2019-6/Wire-Diagram-DBA.pdf

* Oktoberfest Add On Board Wiring: http://s4.american-pinball.com/img/support/2019-5/New-Add-On-Board.pdf

Williams System 9 - 11

2025-03-17T16:00:38Z

Diz: /* Blanking Signal Stuck Low or Pulsing - Adding component info for System 9 */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|500px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_WMS_System_9_Repair|here]] for System 9 and [[Leon_Borre_Williams_System_11_Repair|here]] for System 11.

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM =====
[[File:U25_Ram_Test.jpg|300px|thumb|right|System 11: Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

Note: The CMOS RAM chip is located at U18 for System 9 and U25 for System 11.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode at D3 for System 9 or D2 for System 11 - This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. This diode is a 1N4148.
#Failed diode at D2 for System 9 or D1 for System 11 - This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. This diode is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20 for System 11 or at U56, U57, U60, and U61 for System 9).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail (C12 for System 9). C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will update the displays by sending data to the display 6821 PIA at U51 for System 11 (and U5 for System 9) at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36 (U41 for System 9), in at pin 13, out at pin 12 (in at pin 11 and out at pin 10 for System 9).
#The coupling capacitor at C57 (C15 for System 9) can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 (Q6 for System 9) and to pin 2 of the 555 timer at 1C.
#The 555 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 U51 for System 11 (and U5 for System 9), the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51 for System 11 (U5 for System 9), pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound or missing completely =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C10 is 470pf in 11B, 1800pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C12 is 470pf in 11B, 1200pf in 11A 
    C13 is 4700pf in 11B, 4700pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.

Leon Borre WMS System 9 Repair

2025-03-16T19:45:19Z

Diz:

Repairing Williams system 9 cpu boards

[[Image:swash4.gif]]

'''First i would like to thank Scott Morash (U.S.A.) He did the testing of the new test eproms on his Williams 9 board. I did not find any board and it was time to correct and replace the old test eprom version. The new version has now a memory test and also a new extra test eprom for the " sound" section of the CPU board .'''

This type of cpu board is really the change between older types 3 to 7 towards the new system 11 board. Only 3 pinballs have been made with this type of board: "Space shuttle , Comet and Sorcerer " All circuits except the power circuits are on this cpu board. So the cpu circuits, drivers for solenoids and lights, and sound (which has sound and speech) are on it. (However there is a small extra board attached for the speech.) Because this model was too complicated and to be able to add some extra output chips (PIA's), Williams has split up the design and from this system 11 has been made.

When I first got a board of this type ,I used the schematics of " Sorcerer" The schematics for all System 9 boards are the same so find the schematics here,........... [[Image:pinaqua.gif|link=File:schem9.pdf]]

[[Image:swash1.gif]]

The goal of this article is to do basic repair on the cpu board itself and the 4 connected PIA's (6821). These PIA's pass all signals to the external circuits, displays, coils, lights, and via the switch matrix to all switches. The PIA on U15 is the source off the switch matrix. Afther these test are ok, we do a memory test. And if there is doubth about the sound section, there is now a second test eprom that checks the separated chips of the sound section. The sound section has his own CPU , extra PIA and memory. These the amplifier chip can be tested using the new added extra test eprom . If the cpu memory and PIA's are working, then it's almost sure that the pinball machine will start and you can repair the rest (if necessary) using the build-in tests. If he still doesn't start-up then you'll have to check the program chip . You first have to check if all voltages are ok, which you can do with your dmm.. Don't forget to do this first !!

[[Image:swash1.gif]]

Start

So your pinball machine does not start, but you checked all voltages and they're correct..

First remove the cpu board from the machine. If you're not sure where all connectors go, be sure to label them first ! Once the board is out of the machine, connect it to 5 volts. 

Gnd connected at J17 pins 1,2 or3

 5V at J17 pin 4,5 or 6

Additionally tie 5V from J17 pin 4,5 or 6 to anode of ZR1

[[Image:will9.jpg|200px]]

At the right side of the batteries you'll find the zener diode ZR1, and below it connector 1J17. Connect voltages to this connector, ground goes to pin 3, 5 volts goes to pin 4. You can also get 5 volts at pin 5 and connect this to the top of the zener diode. This can be seen on the picture. You also see a '0' on the display in the center off the board.

[[Image:swash1.gif]]

Usage. 

First you need my test eprom which you plug into U20. (remove the rom and keep it safe!) Like described in my other articles, the test eprom has a non-blocking test which brings all outputs of all 4 PIA's high ( 5) and then low (ground) again. Using a dmm or logic tester you're able to check all outputs and see if there's one not working. If none of the PIA's works then the problem is more general. The display is connected to the PIA in U5, while the test program runs it will show alternating a 0 and a 7.

NOTE: MAKE CERTAIN THAT JUMPER W11 IS REMOVED AND W12 IS INSTALLED. OTHERWISE, LEON'S TEST ROM WILL NOT RUN. Typically, Sorcerer is the only game that uses W11 for the second game ROM at U19. All others only use U20.

The test-eprom for the System 9 boards is an eprom 27128. The program for system 9 tests can be downloaded here, it is a zip file .. [[Image:pinaqua.gif|link=File:will9ver128.zip]] The checksum of this test rom is EDA2 . If you don't have an Eprom-programmer , find someone to burn the rom for you.

[[Image:swash1.gif]]

So if you're lucky then the display will show alternating 0 and 7 so you know the test is working correct. 

There are 4 PIA'S ( U15, U14, U4 en U5), all pins from 2 to 17 have to go from 0 to 5 volt, which can be seen with a dmm. There are however a few exceptions ! PIA U5 pin 9 is not moving , this pin is grounded by a jumper. On PIA U15 are PA0 to PA7 used as input (pins 2 to 9), to see these move you'll have to connect pins 1 to 9 of connector 1J10 to ground.. then you can see the outputs move. 

If one pin doesn't move, short it to the pin next to it. If they now both go up and down, then the PIA is broken, if they both don't move anymore, then or the PIA is broken, or there's a short on the exit which didn't move from the start. To know which of the two possibilities you have, you'll have to deconnect the output ( by cutting the trace (and repairing it afterwards again !!)) and check if he then goes up and down. If so then there's a short, if not then it's certainly the PIA which is broken.

......Worst case scenario...

If the program doesn't run then we'll have to start at the source, which is the CPU-chip-6802 itself. First replace the 6802, this is the fastest.. Use a 6802 of which you are sure it is working fine (or a new one). Same problem ? The jumper is at W12 and not at W11? Then check pins 2, 6 and 40, which have to be positive (around 4 volts). On pin 39 is a clock signal, on pin 4 IRQ; on pin 5 the VMA signal, and on pin 37 the E signal (synchro for external parts). These all have to be around 2 to 3 volts (measured with a dmm). They're alternating signals of which you can find some images below.

[[Image:clock.jpg|200px]] [[Image:vma.jpg|200px]]

The clock signal .....................and the VMA signal

[[Image:esig.jpg|200px]]

The E signal is almost identical to the IRQ signal..

If you find between these 7 signals not the right readings, then you have found the problem. Use the schematic to check where the signal comes from and trace it back to its source. This shouldn't be too hard, the circuits aren't complex. But you'll need the schematics....

The long road... or not!

What's left are the other outputs of the cpu, address lines (pins 9 to 25, except pin 21 which is ground!) and data lines (pins 26 to 33), but also the selection circuit off the test eprom U20 and the selection circuit of the pia's. If the program doesn't work this can be because the test-chip isn't being found by the cpu, or the pia's haven't been found.... How to solve this ? amazingly simple !!!!

It's useless to give you the signals which you would find if the cpu works, as this is not the case. There I found this solution for. Remove the test-eprom from the board and start the board again. The cpu will now work without a program, and run through all its addresses from 0000-0000-0000-0000 to FFFF-FFFF-FFFF-FFFF over and over again.. With this we can continue: all address lines should move. Measure pins 9 to 25 (except pin 21, which is ground), you should get 2 volts on each. Now we've checked all address lines. Now we're almost 100% sure the cpu works. If some pins don't move then it means they have a short. To test this, bend the pin up, plug the cpu chip back in and test.. if it works now then there's a short on this address line. Trace this by cutting the trace in several places until you find the chip which causes the error. The only thing which remains that can be wrong is the selection of the program chips or the PIA's, which we will check now.

The chip selection

We still work without prgram chip. Because the board goes through all addresses, every selectrion address of every PIA is also encountered. Selection pulses arrive on pins 22, 23, 24, 25, 35 and 36 of the pia's. You should find alternating signals, because the positive or negative side of the signals can varie in value, it's best to use the logical test-light which I have described in my page with " Tips and tricks " on my website. It's not always possible to check with a dmm, because some signals are very close to 5 volts, ( only a few milliseconds at 0 volt!!) so you don't see them alternate. With a test light however, both leds are working, one more then the other, but they have to light both.. 

The selection is being continued within the chips by the connected lower addresses, but we have already checked the address lines so we're sure about those.. 

A final case, if something is wrong with one or more data lines. If the above tests are ok, put the test eprom back in U20. The program will run but no data arrives at the pia's. Data lines of the 6802 pin 26 to 33 should move and measure 2 to 3 volts. Is one missing then check for a short. Don't forget that the 6802 has already been replaced so this can not be the source, so we have to have a short on a data line. Can be checked fast by bending the pin of the output upwards and check if the signal now is there on the pin.. If so then there's a short and the buffer is broken, because all data signals go through U23 which buffers them. Inputs are pins 11 to 18 and outputs pins 2 to 9. If the signals go in but don't come out, then the buffer is broken. If one or two signals don't exit, then probably there's a short on these outputs. If that's the case, you'll have to interrups a data line temporary and check which IC is the source of the short.. This takes a lot of time, but it really is the worst case...

Now we've finished and with this method you've got about 95% chance that the basic parts of the cpu work and the pinball starts-up .... good luck!!

Remark

Why don't we have to check the addresses when they arrive on the pia's ? same for data lines ? Because there are 4 pia's, the chance is almost 0 that none of the addresses arrive when we check if they leave the cpu.. same for the data lines.. there's only doubt in the address and data lines which arrive on the eprom in U20. This eprom is in a socket which may have bad contacts.. So do check the socket for bad contacts. 

Memory check: 

Added in June 2005.

To launch the memory test just push the SW1 located near 1J14. The alternating 0/7 on the display will stop ( can stop on 7 or on 0 depending at wich moment you push).Afther a short while it restarts 0/7/0/7..This means memory chip U 18 is ok.

If the display remains on a steady 7 or 0 the memory test indicates a memory fault. Nevertheless the memory test is running continously . We can check if the signals coming to the memory chip are ok. 

Testing the sound section:

The sound section on the CPU board contains a separated CPU chip ( U11) a PIA ( U13) a memory chip ( U12) the sound eprom at U49, the amplifier is U59 and the D/A converter at U48 .

To test this circuitry we place a new test eprom in U49 .

Find the image here , it is to burn into a 27128 ..... [[Image:pinaqua.gif|link=File:soundtest128.zip]] The checksum of this test eprom is FC3E. You can use this test eprom also to test the sound section on a Williams type 11 CPU board. ( see the pages for Williams type 11 repair) 

Before powering up the board, place back the normal game rom at U20 to avoid conflicts with the running test program. Afther power up check if the test is running at pin 15 of U11, the signal there is constantly changing from 0 to 5 volts. If not the program is not running. On the CPU chip ( U11) check the basic signals coming to the cpu chip , like the clock and reset are the same as the ones at the " normal" cpu so as that one was running ok , these signals must to be ok. 

Now we suppose the program is running , test the output pins of the PIA ( U13) pins 10 to 17 they have to " dance" between 0 and 5 volts. Pins 2 to 9 will not move they are hold at 0 volt by a direct connection to the outputs of PIA U4. If the pins 10 to 17 do not move ,check first the selection signal of the PIA ( U13) at pin 23, we need pulses there . If ok change the PIA . If not check the selection chip at U8. Inputs are at pins 1,2,3 and 4 you need pulses at all 4. The output is at pin 14. Only pin 14 can be at 0 volt all others have to be a steady 5. If there is another pin coming to 0 volt the input is bad , if all stay at 0 or 5 volt the chip is bad. 

I assume your PIA is working fine now, We now can proceed to check the amplifier and D/A circuitry.

To produce some sound, and test these we need 12 and -12 volt , Use an old PC power unit this tensions and the 5 volt are all coming from such a power unit. The following connections are needed

 12 at pin 9 of 1J17. -12 at pin 8 of 1J17, a loudspeaker ( 8 ohms) at pins 1 and 4 of 1J15, place jumper W10, and finally as we have no volume potmeter , jumper pins 1 and 2 of 1J16 , this will give us full sound. When connecting 12 volts always remove the temporally jumper between 5 and Z1.

At power up if all is ok you hear this ........ [[Image:pinorang.gif|link=File:toktak.wav]] Sound like a rapid heart-beat, that is the transistion from 5 to 0 volts ...

If not check first the amplifier, touch with your finger pin 2 of 1J16. A loud humm should be the result.

If not replace the amplifier U59.

If the amplifier is ok and still no sound replace the D/A converter at U48.

Checking the sound memory at U12.

Push the SW2 button once ( SW2 is near 1J16) . The outputs of the PIA come to an halt and the sound will stop for a short while, then restarts , this means the memory is ok. If the sound does not restart the test is running continously on the memory test. Check the signals at the memory chip. 

If the signals are ok , replace the 6810 memory chip.

Before placing back the board in the machine do not forget to remove W10 again !!!

Leon Borre WMS System 9 Repair

2025-03-16T19:26:15Z

Diz:

Repairing Williams system 9 cpu boards

[[Image:swash4.gif]]

'''First i would like to thank Scott Morash (U.S.A.) He did the testing of the new test eproms on his Williams 9 board. I did not find any board and it was time to correct and replace the old test eprom version. The new version has now a memory test and also a new extra test eprom for the " sound" section of the CPU board .'''

This type of cpu board is really the change between older types 3 to 7 towards the new system 11 board. Only 3 pinballs have been made with this type of board: "Space shuttle , Comet and Sorcerer " All circuits except the power circuits are on this cpu board. So the cpu circuits, drivers for solenoids and lights, and sound (which has sound and speech) are on it. (However there is a small extra board attached for the speech.) Because this model was too complicated and to be able to add some extra output chips (PIA's), Williams has split up the design and from this system 11 has been made.

When I first got a board of this type ,I used the schematics of " Sorcerer" The schematics for all System 9 boards are the same so find the schematics here,........... [[Image:pinaqua.gif|link=File:schem9.pdf]]

[[Image:swash1.gif]]

The goal of this article is to do basic repair on the cpu board itself and the 4 connected PIA's (6821). These PIA's pass all signals to the external circuits, displays, coils, lights, and via the switch matrix to all switches. The PIA on U15 is the source off the switch matrix. Afther these test are ok, we do a memory test. And if there is doubth about the sound section, there is now a second test eprom that checks the separated chips of the sound section. The sound section has his own CPU , extra PIA and memory. These the amplifier chip can be tested using the new added extra test eprom . If the cpu memory and PIA's are working, then it's almost sure that the pinball machine will start and you can repair the rest (if necessary) using the build-in tests. If he still doesn't start-up then you'll have to check the program chip . You first have to check if all voltages are ok, which you can do with your dmm.. Don't forget to do this first !!

[[Image:swash1.gif]]

Start

So your pinball machine does not start, but you checked all voltages and they're correct..

First remove the cpu board from the machine. If you're not sure where all connectors go, be sure to label them first ! Once the board is out of the machine, connect it to 5 volts. 

Gnd connected at J17 pins 1,2 or3

 5V at J17 pin 4,5 or 6

Additionally tie 5V from J17 pin 4,5 or 6 to anode of ZR1

[[Image:will9.jpg|200px]]

At the right side of the batteries you'll find the zener diode VR1, and below it connector 1J17. Connect voltages to this connector, ground goes to pin 3, 5 volts goes to pin 4. You can also get 5 volts at pin 5 and connect this to the top of the zener diode. This can be seen on the picture. You also see a '0' on the display in the center off the board.

[[Image:swash1.gif]]

Usage. 

First you need my test eprom which you plug into U20. (remove the rom and keep it safe!) Like described in my other articles, the test eprom has a non-blocking test which brings all outputs of all 4 PIA's high ( 5) and then low (ground) again. Using a dmm or logic tester you're able to check all outputs and see if there's one not working. If none of the PIA's works then the problem is more general. The display is connected to the PIA in U5, while the test program runs it will show alternating a 0 and a 7.

NOTE: MAKE CERTAIN THAT JUMPER W11 IS REMOVED AND W12 IS INSTALLED. OTHERWISE, LEON'S TEST ROM WILL NOT RUN. Typically, Sorcerer is the only game that uses W11 for the second game ROM at U19. All others only use U20.

The test-eprom for the System 9 boards is an eprom 27128. The program for system 9 tests can be downloaded here, it is a zip file .. [[Image:pinaqua.gif|link=File:will9ver128.zip]] The checksum of this test rom is EDA2 . If you don't have an Eprom-programmer , find someone to burn the rom for you.

[[Image:swash1.gif]]

So if you're lucky then the display will show alternating 0 and 7 so you know the test is working correct. 

There are 4 PIA'S ( U15, U14, U4 en U5), all pins from 2 to 17 have to go from 0 to 5 volt, which can be seen with a dmm. There are however a few exceptions ! PIA U5 pin 9 is not moving , this pin is grounded by a jumper. On PIA U15 are PA0 to PA7 used as input (pins 2 to 9), to see these move you'll have to connect pins 1 to 9 of connector 1J10 to ground.. then you can see the outputs move. 

If one pin doesn't move, short it to the pin next to it. If they now both go up and down, then the PIA is broken, if they both don't move anymore, then or the PIA is broken, or there's a short on the exit which didn't move from the start. To know which of the two possibilities you have, you'll have to deconnect the output ( by cutting the trace (and repairing it afterwards again !!)) and check if he then goes up and down. If so then there's a short, if not then it's certainly the PIA which is broken.

......Worst case scenario...

If the program doesn't run then we'll have to start at the source, which is the CPU-chip-6802 itself. First replace the 6802, this is the fastest.. Use a 6802 of which you are sure it is working fine (or a new one). Same problem ? The jumper is at W12 and not at W11? Then check pins 2, 6 and 40, which have to be positive (around 4 volts). On pin 39 is a clock signal, on pin 4 IRQ; on pin 5 the VMA signal, and on pin 37 the E signal (synchro for external parts). These all have to be around 2 to 3 volts (measured with a dmm). They're alternating signals of which you can find some images below.

[[Image:clock.jpg|200px]] [[Image:vma.jpg|200px]]

The clock signal .....................and the VMA signal

[[Image:esig.jpg|200px]]

The E signal is almost identical to the IRQ signal..

If you find between these 7 signals not the right readings, then you have found the problem. Use the schematic to check where the signal comes from and trace it back to its source. This shouldn't be too hard, the circuits aren't complex. But you'll need the schematics....

The long road... or not!

What's left are the other outputs of the cpu, address lines (pins 9 to 25, except pin 21 which is ground!) and data lines (pins 26 to 33), but also the selection circuit off the test eprom U20 and the selection circuit of the pia's. If the program doesn't work this can be because the test-chip isn't being found by the cpu, or the pia's haven't been found.... How to solve this ? amazingly simple !!!!

It's useless to give you the signals which you would find if the cpu works, as this is not the case. There I found this solution for. Remove the test-eprom from the board and start the board again. The cpu will now work without a program, and run through all its addresses from 0000-0000-0000-0000 to FFFF-FFFF-FFFF-FFFF over and over again.. With this we can continue: all address lines should move. Measure pins 9 to 25 (except pin 21, which is ground), you should get 2 volts on each. Now we've checked all address lines. Now we're almost 100% sure the cpu works. If some pins don't move then it means they have a short. To test this, bend the pin up, plug the cpu chip back in and test.. if it works now then there's a short on this address line. Trace this by cutting the trace in several places until you find the chip which causes the error. The only thing which remains that can be wrong is the selection of the program chips or the PIA's, which we will check now.

The chip selection

We still work without prgram chip. Because the board goes through all addresses, every selectrion address of every PIA is also encountered. Selection pulses arrive on pins 22, 23, 24, 25, 35 and 36 of the pia's. You should find alternating signals, because the positive or negative side of the signals can varie in value, it's best to use the logical test-light which I have described in my page with " Tips and tricks " on my website. It's not always possible to check with a dmm, because some signals are very close to 5 volts, ( only a few milliseconds at 0 volt!!) so you don't see them alternate. With a test light however, both leds are working, one more then the other, but they have to light both.. 

The selection is being continued within the chips by the connected lower addresses, but we have already checked the address lines so we're sure about those.. 

A final case, if something is wrong with one or more data lines. If the above tests are ok, put the test eprom back in U20. The program will run but no data arrives at the pia's. Data lines of the 6802 pin 26 to 33 should move and measure 2 to 3 volts. Is one missing then check for a short. Don't forget that the 6802 has already been replaced so this can not be the source, so we have to have a short on a data line. Can be checked fast by bending the pin of the output upwards and check if the signal now is there on the pin.. If so then there's a short and the buffer is broken, because all data signals go through U23 which buffers them. Inputs are pins 11 to 18 and outputs pins 2 to 9. If the signals go in but don't come out, then the buffer is broken. If one or two signals don't exit, then probably there's a short on these outputs. If that's the case, you'll have to interrups a data line temporary and check which IC is the source of the short.. This takes a lot of time, but it really is the worst case...

Now we've finished and with this method you've got about 95% chance that the basic parts of the cpu work and the pinball starts-up .... good luck!!

Remark

Why don't we have to check the addresses when they arrive on the pia's ? same for data lines ? Because there are 4 pia's, the chance is almost 0 that none of the addresses arrive when we check if they leave the cpu.. same for the data lines.. there's only doubt in the address and data lines which arrive on the eprom in U20. This eprom is in a socket which may have bad contacts.. So do check the socket for bad contacts. 

Memory check: 

Added in June 2005.

To launch the memory test just push the SW1 located near 1J14. The alternating 0/7 on the display will stop ( can stop on 7 or on 0 depending at wich moment you push).Afther a short while it restarts 0/7/0/7..This means memory chip U 18 is ok.

If the display remains on a steady 7 or 0 the memory test indicates a memory fault. Nevertheless the memory test is running continously . We can check if the signals coming to the memory chip are ok. 

Testing the sound section:

The sound section on the CPU board contains a separated CPU chip ( U11) a PIA ( U13) a memory chip ( U12) the sound eprom at U49, the amplifier is U59 and the D/A converter at U48 .

To test this circuitry we place a new test eprom in U49 .

Find the image here , it is to burn into a 27128 ..... [[Image:pinaqua.gif|link=File:soundtest128.zip]] The checksum of this test eprom is FC3E. You can use this test eprom also to test the sound section on a Williams type 11 CPU board. ( see the pages for Williams type 11 repair) 

Before powering up the board, place back the normal game rom at U20 to avoid conflicts with the running test program. Afther power up check if the test is running at pin 15 of U11, the signal there is constantly changing from 0 to 5 volts. If not the program is not running. On the CPU chip ( U11) check the basic signals coming to the cpu chip , like the clock and reset are the same as the ones at the " normal" cpu so as that one was running ok , these signals must to be ok. 

Now we suppose the program is running , test the output pins of the PIA ( U13) pins 10 to 17 they have to " dance" between 0 and 5 volts. Pins 2 to 9 will not move they are hold at 0 volt by a direct connection to the outputs of PIA U4. If the pins 10 to 17 do not move ,check first the selection signal of the PIA ( U13) at pin 23, we need pulses there . If ok change the PIA . If not check the selection chip at U8. Inputs are at pins 1,2,3 and 4 you need pulses at all 4. The output is at pin 14. Only pin 14 can be at 0 volt all others have to be a steady 5. If there is another pin coming to 0 volt the input is bad , if all stay at 0 or 5 volt the chip is bad. 

I assume your PIA is working fine now, We now can proceed to check the amplifier and D/A circuitry.

To produce some sound, and test these we need 12 and -12 volt , Use an old PC power unit this tensions and the 5 volt are all coming from such a power unit. The following connections are needed

 12 at pin 9 of 1J17. -12 at pin 8 of 1J17, a loudspeaker ( 8 ohms) at pins 1 and 4 of 1J15, place jumper W10, and finally as we have no volume potmeter , jumper pins 1 and 2 of 1J16 , this will give us full sound. When connecting 12 volts always remove the temporally jumper between 5 and Z1.

At power up if all is ok you hear this ........ [[Image:pinorang.gif|link=File:toktak.wav]] Sound like a rapid heart-beat, that is the transistion from 5 to 0 volts ...

If not check first the amplifier, touch with your finger pin 2 of 1J16. A loud humm should be the result.

If not replace the amplifier U59.

If the amplifier is ok and still no sound replace the D/A converter at U48.

Checking the sound memory at U12.

Push the SW2 button once ( SW2 is near 1J16) . The outputs of the PIA come to an halt and the sound will stop for a short while, then restarts , this means the memory is ok. If the sound does not restart the test is running continously on the memory test. Check the signals at the memory chip. 

If the signals are ok , replace the 6810 memory chip.

Before placing back the board in the machine do not forget to remove W10 again !!!

Williams System 9 - 11

2025-03-13T00:58:00Z

Diz: /* Steps for Repairing a Dead MPU */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|500px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_WMS_System_9_Repair|here]] for System 9 and [[Leon_Borre_Williams_System_11_Repair|here]] for System 11.

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM =====
[[File:U25_Ram_Test.jpg|300px|thumb|right|System 11: Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

Note: The CMOS RAM chip is located at U18 for System 9 and U25 for System 11.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode at D3 for System 9 or D2 for System 11 - This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. This diode is a 1N4148.
#Failed diode at D2 for System 9 or D1 for System 11 - This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. This diode is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail. C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will update the displays by sending data to the display 6821 PIA at U51 at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36, in at pin 13, out at pin 12.
#The coupling capacitor at C57 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 and to pin 2 of the 555 timer at 1C.
#The 555 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 U51, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound or missing completely =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C10 is 470pf in 11B, 1800pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C12 is 470pf in 11B, 1200pf in 11A 
    C13 is 4700pf in 11B, 4700pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.

Williams System 9 - 11

2025-03-13T00:57:07Z

Diz: /* Steps for Repairing a Dead MPU */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|500px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_Williams_System_9_Repair|here]] for System 9 and [[Leon_Borre_Williams_System_11_Repair|here]] for System 11.

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM =====
[[File:U25_Ram_Test.jpg|300px|thumb|right|System 11: Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

Note: The CMOS RAM chip is located at U18 for System 9 and U25 for System 11.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode at D3 for System 9 or D2 for System 11 - This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. This diode is a 1N4148.
#Failed diode at D2 for System 9 or D1 for System 11 - This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. This diode is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail. C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will update the displays by sending data to the display 6821 PIA at U51 at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36, in at pin 13, out at pin 12.
#The coupling capacitor at C57 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 and to pin 2 of the 555 timer at 1C.
#The 555 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 U51, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound or missing completely =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C10 is 470pf in 11B, 1800pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C12 is 470pf in 11B, 1200pf in 11A 
    C13 is 4700pf in 11B, 4700pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.

Williams System 9 - 11

2025-03-13T00:56:31Z

Diz: /* MPU boot issues - added link to Leon's repair notes for System 9 */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|500px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_Williams_System_9_Repair|here]]for System 9 and [[Leon_Borre_Williams_System_11_Repair|here]] for System 11.

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM =====
[[File:U25_Ram_Test.jpg|300px|thumb|right|System 11: Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

Note: The CMOS RAM chip is located at U18 for System 9 and U25 for System 11.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode at D3 for System 9 or D2 for System 11 - This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. This diode is a 1N4148.
#Failed diode at D2 for System 9 or D1 for System 11 - This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. This diode is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail. C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will update the displays by sending data to the display 6821 PIA at U51 at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36, in at pin 13, out at pin 12.
#The coupling capacitor at C57 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 and to pin 2 of the 555 timer at 1C.
#The 555 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 U51, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound or missing completely =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C10 is 470pf in 11B, 1800pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C12 is 470pf in 11B, 1200pf in 11A 
    C13 is 4700pf in 11B, 4700pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.

Williams System 9 - 11

2025-02-01T21:07:03Z

Diz: /* Testing for Battery Backup Power at the RAM (U25) */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|400px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_Williams_System_11_Repair|here]].

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM =====
[[File:U25_Ram_Test.jpg|300px|thumb|right|System 11: Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

Note: The CMOS RAM chip is located at U18 for System 9 and U25 for System 11.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode at D3 for System 9 or D2 for System 11 - This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. This diode is a 1N4148.
#Failed diode at D2 for System 9 or D1 for System 11 - This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. This diode is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail. C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will send data to the display 6821 PIA at U51 (pin 4) at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36, in at pin 13, out at pin 12.
#The coupling capacitor at C57 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 and to pin 2 of the 555 timer at 1C.
#The 555 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 U51, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C12 is 470pf in 11B, 1200pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C10 is 470pf in 11B, 1800pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.

Williams System 9 - 11

2025-02-01T20:56:51Z

Diz: /* Steps for Repairing a Dead MPU */

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

==Introduction==

[[File:Wms sys9 boardset.jpg‎|300px|thumb|left|Williams System 9 Board Set from Space Shuttle]]
[[File:System11NothingBackbox.jpg|thumb|right|300px|Williams System 11 (nothing) Board Set from High Speed]]
[[File:WMS Sys11 Boardset.JPG|thumb|left|300px|Williams System 11A Board Set from Pinbot]]
[[File:WMS Jokerz Boardset.JPG|thumb|right|300px|Williams System 11b Board Set from Jokerz! (Note that power supply is a prototype)]]
[[File:WMS Sy11B Boardset.JPG|300px|thumb|left|System 11b Board Set from Transporter the Rescue]]
[[File:WMS_Sys11C_Boardset.JPG|thumb|right|300px|System 11c Board Set from Rollergames]] 
The Williams system 7 boardset was replaced in 1984 with the system 9 boardset, and then again in 1985 with the system 11 boardset. Combining the driver board, sound board, and cpu directly onto one board eliminated several design deficiencies of the earlier 3-7 boardsets; mainly the 40 pin interconnector, and extra wiring harness inter-board connectors. Larger ROMs could be fitted directly onto the boards allowing for more complex rulesets and sounds.
 

The System 9 and System 11 board sets are not 100% compatible. With a fair amount of effort, a System 11 board could be made compatible with a System 9, but it is not worth the extended effort to change the jumpers. It's far easier to just modify the rom images so that they are plug and play when installed in a System 11 CPU. You can find them already on the ipdb. The primary differences between the System 9 and System 11 board sets are the sound system and rom space.
(add more info later)

As time went on, the System 11 board set underwent some changes too. The power supply, sound board, and CPU / driver board have minor changes. More apparent was the addition of circuit boards. Starting with the 11a board set, a more complex sound board was added (System 11 sound boards are strictly background sounds only). Later in the System 11 series, sound functions were partially (11B) or fully removed (11C) from the MPU, and eventually were solely handled by a dedicated sound board. Game-specific interconnect boards and auxiliary power driver boards were introduced in System 11B games. The interconnect boards acted as a pass-through for switch, lamp, flasher, and solenoid signal lines and circuits. It also allowed circuits with different voltages to share the same power source by using current limiting resistors to drop voltages to the appropriate levels. All general illumination fuses were moved to this board. The auxiliary power driver board has the AC relay, which finally centralized the location of it. Likewise, several fuses, beefier TIP36C transistors, and bridge rectifiers are centralized on the auxiliary power driver board.

 

==Games==
===System 9===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-

|Strike Zone|| 1984 || 1916 || unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Star Light|| 06-1984 || 530 || no speech || || 5610-09563-00 || only a few were made with System 9 boards inside
|-
|Space Shuttle|| 12-1984 || 535 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Sorcerer|| 03-1985 || 532 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|-
|Comet|| 06-1985 || 540 || C-10716 (Speech only) || || 5610-09563-00 and 5610-10355-00 ||
|}

===System 11===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Alley Cats|| 10-1985 || 1918 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|[[High Speed]]|| 01-1986 || 541 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Grand Lizard|| 04-1986 || 523 || C-11030 (Background sound only) || || 5610-10897-00 ||
|-
|Road Kings|| 07-1986 || 542 || D-11197-542 (Background music only) || || 5610-10897-00 ||
|}

===System 11A===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Other Boards
!Transformer
!Notes
|-
|Pinbot|| 10-1986 || 549 || D-11297-549 (Background Speech & Sound) || || 5610-10897-00 ||
|-
|Tic Tac Strike|| 11-1986 || 1919 || Unknown || || || This is a shuffle alley which uses some pinball boards
|-
|Millionaire|| 01-1987 || 555 || [[Media:WMS Sys11 Sound D-11298-555.JPG | D-11298-555]] (Background Speech & Sound) || || 5610-10897-00 ||
|-
|F-14 Tomcat|| 03-1987 || 554 || D-11298-554 (Used on 1st 5,000 games - Background Speech & Sound) / D-11581-554 || || 5610-12136-00 ||
|-
|Fire!|| 08-1987 || 556 || D-11581-556 || || 5610-12136-00 ||
|-
|Fire! Champagne Edition|| 09-1987 || 556 || D-11581-556 || || ||
|}

===System 11B===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Power Supply
!Aux Power Driver
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|Big Guns|| 10-1987 || 557 || D-11581-557 || D-8345-557 || D-11583-557 || C-11762 || Uses D-11814 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Space Station]]|| 12-1987 || 552 || D-11581-552 || D-8345-557 || D-11813-552 || C-11762-552 || Uses D-11814-552 Flash Lamp Resistor Board || 5610-12136-00 ||Uses special solenoid switches
|-
|Gold Mine|| 01-1988 || 1920 || None || D-8345-1914 || None || None || || || This is a shuffle alley which uses some pinball boards
|-
|Cyclone|| 02-1988 || 564 ||[[Media:WMS Sys11 Sound D-11581-564.JPG | D-11581-564]] || D-8345-557 || D-11813-574 || C-11762-564|| Uses D-11814-564 Flash Lamp Resistor Board || 5610-12136-00 ||Does not use special solenoid switches
|-
|Banzai Run|| 05-1988 || 566 || D-11581-566 || D-8345-566 ||D-12247-566 || D-12112 || || 5610-12136-00 ||Uses special solenoid switches
|-
|[[Swords of Fury]]|| 06-1988 || 559 || D-11581-559 || D-8345-557 || D-12247-559 || D-12313-559 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Taxi|| 08-1988 || 553 || D-11581-553 || D-12246-553 || D-12247-559 || D-12313-553 || || 5610-12136-00 ||Uses special solenoid switches
|-
|Top Dawg|| 11-1988 || 1921 || None || D-12246 || None || D-12313-1921 || || || This is a shuffle alley which uses some pinball boards
|-
|Jokerz!|| 12-1988 || 567 || D-12338-567 || D-12246 || D-12247-559|| D-12313-567 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Earthshaker]]|| 02-1989 || 568 || [[Media:System 11 Sound Board.JPG | D-11581-568]] || D-12246-568 || D-12247-559 || D-12313-568|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Black Knight 2000]]|| 04-1989 || 563 || [[Media:WMS Sys11 Sound D-11581-585.JPG | D-11581-585]] || D-12246 || D-12247-563 || D-12313-563|| || 5610-12136-00 ||Uses special solenoid switches
|-
|Transporter the Rescue|| 04-1989 || 2008 || D-11581-2008 || D-12246 || D-12247-2008|| D-12313-2008 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Police Force|| 08-1989 || 573 || D-11581-573 || D-12246 || D-12247-566 || D-12313-573|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Shuffle Inn|| 10-1989 || 1922 || None (assumed) || D-12246 (assumed) || None || D-12313-1922 (assumed)|| || || This is a shuffle alley which uses some pinball boards
|-
|Elvira and the Party Monsters|| 10-1989 || 2011 || D-11581-2011 || D-12246 || D-12247-2011|| D-12313-2011 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|Bad Cats|| 11-1989 || 575 || D-11581-575 || D-12246 || D-12247-566 || D-12313-575|| || 5610-12136-00 ||Does not use special solenoid switches
|-
|Mousin' Around!|| 12-1989 || 2009 || D-11581-2009 || D-12246 ||D-12247-2009 || D-12313-2209 || || 5610-12136-00 ||Does not use special solenoid switches
|-
|[[Whirlwind]]|| 01-1990 || 574 || D-11581-574 || D-12246 || D-12247-574 ||D-12313-574 || Uses a C-13287 Sound Overlay Solenoid Board to control 5 extra devices || 5610-12136-00 ||Does not use special solenoid switches
|}

===System 11C===

{| class="wikitable"
!Title
!Date of Release
!Model #
!Sound
!Master Interconnect
!Other Boards
!Transformer
!Notes
|-
|The Bally Game Show|| 04-1990 || 2003 || D-11581-2003 w/ 512K ROMS|| D-12313-2003 || Uses a C-13286 Sound Overlay Lamp Board || 5610-12136-00 || Does not use special solenoid switches
|-
|Pool Sharks|| 06-1990 || 2014 || D-11581-2014 w/ 512K ROMS|| D-12313-2014 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Rollergames]]|| 06-1990 || 576 || D-11581-576 w/ 512K ROMS|| D-12313-576 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Diner|| 09-1990 || 571 || D-11581-571 w/ 512K ROMS|| D-12313-571 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Radical!|| 09-1990 || 2015 || D-11581-2015 w/ 512K ROMS|| D-12313-2015 || || 5610-12136-00 || Does not use special solenoid switches
|-
|Dr. Dude|| 11-1990 || 2016 || D-11581-2016 w/ 512K ROMS|| D-12313-2016 || || 5610-12136-00 || Does not use special solenoid switches
|-
|[[Riverboat Gambler]]|| 11-1990 || 50007 || D-11581-50007 w/ 512K ROMS (assumed) || D-12313-50007|| || 5610-12136-00 || Does not use special solenoid switches
|-
|Bugs Bunny's Birthday Ball|| 01-1991 || 20009 || D-11581-20009 w/ 512K ROMS|| D-12313-20009 || || 5610-12136-00 || Does not use special solenoid switches
|}

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

==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.

====Documentation Errors====
* Error on the [[High_Speed#MPU_Schematics_Error_for_U21_.26_U22|MPU I/O signals for U21 / U22 of High Speed]].
* [[#Flipper_Circuit_Schematics_Error|Flipper Circuit Schematics Error]] in the manuals for High Speed, Grand Lizard, and Road Kings.

===Theory of Operation & Schematics===
Details for board and cabinet schematics System 9-11 games can be found in the game manual or parts catalogs. Some copies can be found on [http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK Planetary Pinball] or on [http://www.ipdb.org/ IPDB].

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

|-
|Williams
|Pinball Troubleshooting & Reference Manual
|69-8955 (April 21, 1986)
|[[file:placeholder.jpg|thumb|left|140px]]
|[[media:Williams-pinball-troubleshooting-reference-manual_16-8955_sys9.pdf|PDF]]
|Comet, High Speed, Sorcerer, Space Shuttle, Star Light
|System 9 games. Also includes Strike Zone shuffle alley game.

|}

===Schematics===
* [[media:Audio_schem_11581.pdf|D-11581 Sound Board]]

===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 (1986-1989)
|16-9064-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/rvsk/ Viewer] [[media:Williams-parts-catalog-blue-book_16-9064-B.pdf|PDF]]
|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
|

|-
|Williams
|Red Parts Catalog (1989-1992)
|16-9190-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/feme/ Viewer] [[media:Williams-parts-catalog-red-book_16-9190-B.pdf|PDF]]
|Bad Cats, Diner, Dracula, Fish Tales, Funhouse, The Getaway, Hurricane, The Machine, Riverboat Gambler, Rollergames, Slugfest, Terminator 2, Whirlwind, White Water
|

|-
|Bally/Midway
|Yellow Parts Catalog (1988-1992)
|16-9147-B
|[[file:placeholder.jpg|thumb|left|140px]]
|[https://online.fliphtml5.com/vrtyz/itjk/ Viewer] [[media:Bally-midway-parts-catalog-yellow-book_16-9147-B.pdf|PDF]]
|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
|

|}

===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
!Version
!Cover
!Source
!Games
!Notes

|-
|Williams
|Service Bulletin Book, 1989
|[[file:Williams-Service-Bulletin-Book-1989-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1989.pdf|PDF]]
|Cyclone, Bonzai Run, Taxi, Earthshaker, Truck Stop, Transporter
|

|-
|Williams
|Service Bulletin Book, 1990
|[[file:Williams-1990-service-bulletin-cover.jpg|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1990.pdf|PDF]]
|Diner, Police Force, Pool Sharks, Rollergames
|

|-
|Williams
|Service Bulletin Book, 1991
|[[file:Williams-1991-service-bulletin-book-cover.png|thumb|left|140px]]
|[[media:Williams-service-bulletin-book-1991.pdf|PDF]]
|Dr. Dude, Jokerz, Riverboat Gambler
|This book includes some WPC games

|}

==Technical Info==
System 9 eliminated a huge issue with the earlier system 3 through 7 boardsets, the 40 pin interconnect between the MPU and Driver boards. All circuitry previously separated into MPU, driver, and sound boards was combined into a single MPU board. Satellite boards were still used for displays, speech, and solenoid expansion.

Starting with '''Big Guns''', Williams introduced another weak link into their system, the interconnect board. Initial implementations were used to disperse the general illumination between the playfield and backbox. The connectors on interconnect boards were prone to overheating and failure just like prior implementations. At the same time, flash lamp resistor boards were being used. These were created to collocate all of the flashlamp current limiting resistors, and eliminate under playfield flashlamp resistor boards, which had proven themselves problematic in the high heat, high vibration environment under the playfield. Resistors often desoldered themselves and/or vibrated so much that the connection fractured. Flash lamp resistor boards were only used on three games: Big Guns, Space Station, and Cyclone. In addition to the interconnect and the flash lamp resistor board, the auxiliary power driver board made its appearance. The auxiliary power driver board housed all of the high current transistors (TIP36c), solenoid and flasher fuses (including discrete flipper fuses), the AC select relay, and the solenoid power bridge rectifiers. The auxiliary power driver board did go through some minor changes, but it was functionally equivalent through the last System 11C game.

Starting with Banzai Run, a more standardized interconnect board was created. This interconnect board merged the general illumination interconnect with the flasher driver board. Switch and lamp circuits passed directly through this board as a matter of manufacturing convenience. Later interconnect boards added 3 opto couplers to indicate when the flippers and AC relay were activated (the same circuitry as used in the flipper power section of the WPC-089 -1 Power/Driver board).

One of the largest advantages of the system 11 board set is its ability to switch one set of coil driver transistors between 2 sets of coils/flashers. This is accomplished via a relay on a separate board called the A/C select relay (the A/C select relay was eventually moved to the auxiliary power driver board starting with Big Guns). The theory is that coils that are less frequently activated will be on the A side of the relay, and that flashers will be on the C side of the relay. Most of the time during gameplay, the C side is active, enabling the flashers. If the driver transistor for the A/C select relay itself shorts, the relay defaults to the coil side, allowing the game to continue to operate in a reasonable fashion (usually the A side coils are the ball shooter lane, drop target resets, VUK - basically coils that don't need to be able to operate 100% of the time unlike a slingshot coil or pop bumper coil). Data East's board set was essentially a copy of the system 11 board set, but Data East programmed it the opposite way, so that the flasher side of the A/C select relay is active by default. Data East games, when the A/C relay doesn't operate, just sits there and flashes lamps instead of playing.

System 9 and early System 11 games do share a disadvantage with the earlier 3-7 board sets, they still utilize special solenoid circuitry. The pops and slings on system 9/11 games do not activate via a switch which is seen by the MPU's program which fires the coil. Instead, the switches directly fire their associated coils via logic gates on the main board. The main disadvantage with this system is that the solenoids fire continuously as long as their activation switch is closed. A locked on sling or pop will burn out components quickly. It is recommended to add a 1, 1.5, or 2 amp inline fuse to each coil on a directly fired system 11 game. Usually just the pops and slings are direct fired coils. However, other coils were designated to the special solenoids.

Later System 11 games did not use the direct fire solenoid switches. Switches on the switch matrix were used instead. To easily identify games which do not use direct fire solenoid switches, IJ18 on the MPU board will not have a harness connection attached to it. Likewise, the slingshots and pop bumpers will no longer have a set of scoring switches.

One way that System 9 games differ from the previous 3-7 board set is that the special solenoids are not controlled by the CPU at all. In other words, the special solenoids are not pulsed during solenoid test, as the physical board architecture does allow for this.

The software in system 9-11 games continued with the same machine architecture from system 6 and 7, except for the special solenoids as mentioned above. More ram became available, up to 2k, but no game used over 800 bytes. This is likely due to the lower cost of 6264 RAM than 6116 RAM as was used in early System 9-11 games more than any other reason. Additional diagnostics in the form of switch error checking appeared in system 11. Any switch not activated over 30 games (16 games for flipper switches) would cause an error to be called out at power on. The software was able to compensate for broken switches by designating another switch to perform the same function as the broken switch. 

===MPU Driver Boards===
[[File:WMSSystem9MPU.jpg |300px|thumb|left|System 9 MPU]]
[[File:System9MPUFactoryMod.jpg |300px|thumb|right|These high frequency filter capacitors were added at the factory, and are normal. Their purpose is the snub high frequency noise in the Advance and Auto Up/Down coin door button circuits.]] 
'''System 9 MPU'''
Williams used a single version of the System 9 MPU in all System 9 games. A few minor modifications to the board may have been made, but it's essentially the same board for the entire 3 game run of Space Shuttle, Sorcerer, and Comet. The picture at left shows an early board that featured two inductors (copper wound coils that "smooth" DC power) at L1 and L2, adjacent to connector 1J17. Later revisions of the board used "zero ohm" jumpers instead, presumably to reduce cost.
 

[[File:WilliamsSystem10MPUFront.jpg ‎|300px|thumb|left|Williams System 10 MPU component side. Image courtesy of Brian Johnson.]]
[[File:WilliamsSystem10MPUBack.jpg ‎|300px|thumb|right|Williams System 10 MPU solder side. Image courtesy of Brian Johnson.]] 
Williams released a single game using an MPU board designated '''System 10'''. The game "4-in-1" ([https://www.ipdb.org/search.pl?any=4-in-1&sortby=name&search=Search+Database&searchtype=quick IPDB link]) was released in 1985 and is more like Pachinko than pinball.

From the Internet Pinball Database:

"This game is known in Williams documentation as "4-IN-1" but that name never appears on the game itself. A total of 100 games were produced. Each came with four interchangeable playfield overlays for the themes of Baseball, Poker, Football, and Soccer. The operator could change the overlay and Instruction Card, re-option switches, and have a new game in the same cabinet."
 

'''System 11''' games used one of four different revisions of the System 11 MPU. The first version of the System 11 MPU was completely self-contained, able to make game sounds on the board. A simple background sound board was used to add some game sounds. Between the baseline revision of the System 11 MPU and the last revision of the MPU (System 11C) incrementally more of the sound processing and sound circuitry was removed from the board (not stuffed). None of the System 11 shuffle alley games use a separate sound board.

[[File:WilliamsSystem11CPU.jpg|300px|thumb|left|Early System 11 (nothing) MPU]]
[[File:System11NothingLater.jpg|300px|thumb|right|Later System 11 (nothing) MPU. Note extensive alkaline corrosion abatement, NVRAM install, and use of modern reset generator. Image courtesy of Chris Hibler]] 
'''System 11 (nothing) MPU''' 
This picture shows the early System 11 MPU. A later revision of this MPU, pictured at right, has an additional jumper W16 located between the 7 segment diagnostic display and the relay, and a 4.7K ohm resistor between the 7447 and the resistor DIP. The early PCB on the left has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.
 

[[File:System11ZenerDiodeAddition.jpg|300px|thumb|left|6.2V Zener Diodes added to the back of the System 11 (nothing) MPU. These zeners were added to the layout of the PCB in subsequent revisions of the board (11A, etc).]]
[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|right|6.2V Zener Diodes (ZR3-ZR8) incorporated into the board layout and stuffed at the factory on a later board revision. Note: in this image, ZR7 and ZR8 have been replaced]] 
The picture at left shows six 6.2V zener diodes added to the solder side of a System 11 (nothing) MPU. These zeners were left off the factory silkscreen of the board. Later revisions of the System 11 MPU added them to the component side of the board. Their purpose is to protect the special solenoid switch inputs. Either a ZPY6,2/ZD6,2/1N4735A (1 watt) or ZF5,2/1N5234B (1/2 watt) can be used. This mod is purely optional. In reality the diode doesn't help much if you short the switch input with the solenoid voltage. In this case the diode and the 7402 are usually damaged and need to be replaced.
 
Additionally, if the System 11 (nothing) MPU is used in a System 11A game or later, pins 6 and 7 of the adjacent connector (J18) must be tied to the ground plane at the edge of the board. These pins provide the ground for the special solenoids. Without the modification they do not work. Some early System 11A pins might not need the mod. If unsure just check if a cable is connected to pin 6 or 7 in your game.
 

[[File:CPUWilliamsSystem11A-PB.jpg|300px|thumb|left|A rare prototype System 11a MPU]]
[[File:System11aTransitionVersion.jpg|300px|thumb|right|Blanking, 5VDC, and Diagnostic LEDs factory installed in a "transition" vintage System 11a MPU. The prior version 7447 (U48) and resistor DIP (U47) has been replaced with a 7407, discrete resistors and LEDs.]]
[[File:System11TransitionTag.jpg|300px|thumb|left|A prototype System 11a MPU with original label]] 
'''System 11a ''Prototype'' MPU''' 
This MPU was only used in Pin Bot. It's actually a System 11 (nothing) MPU PCB layout, with the 7 segment LED display replaced at the factory with 3 LEDs as used in all later System 11 MPUs (11A/B/C). The latest trace revision of this board also has the ground mod (connect 1J18, pins 6 and 7 to board ground) allowing it to work in any 11A/B/C game without modification. According to a friend it was referred to by the name of 11a instead of 11A by distributors.
 

[[File:CPUWilliamsSystem11A.jpg|300px|thumb|left|A late production System 11A MPU.]] 
'''System 11A MPU''' 
The System 11A MPU can be used in all System 11 games. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and possibly the amplifier section must be stuffed. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board. On early production system 11A boards, the amplifier section was fully stuffed, just like the original System 11 board. Later in the production of System 11A boards, the amplifier section was not stuffed, just like an 11B board. But unlike System 11B boards, the System 11A board still has the same switch section layout as the original System 11 MPU, making it easy to identify.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:System 11 CPU Driver Board.JPG|300px|thumb|left|System 11B MPU. Note that a large portion of the sound circuitry, including the TDA2002 amp, was not stuffed in late System 11A boards or any System 11B MPU boards.]] 
'''System 11B MPU''' 
The System 11B MPU can be used in all System 11 games too. If used in one of the four first System 11 games (Alley Cats, High Speed, Grand Lizard, and Road Kings), connector 1J15 and all of the sound amplification components must be added to the board. System 11A, 11B, and 11C games don't use the amplifier section of the MPU board. Sound amplification is accomplished on the sound board.

'''Note:''' the sound mixing section of the System 11A MPU is stuffed with different resistor and capacitor values than that of the System 11B MPU. This may cause some sound quality differences as has been noted with EarthShaker.
 

[[File:CPUWilliamsSystem11C.jpg|300px|thumb|left|System 11C MPU. Note that none of the sound circuitry, including the 6802 processor and 6821 PIA, is stuffed in System 11C MPU boards. All sounds were generated by the sound board.]] 
'''System 11C MPU''' 
The System 11C MPU can be used only in System 11C games since none of the sound processing circuitry was stuffed. It can be used in games prior to 11C, if the sound section is populated. However, some of the components needed are rare and / or costly, and there are a fair amount to install. If there is no other choice but to use this board, it is possible.
 

[[File:RottenDogMPU9211.jpg|300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU]]
[[File:RottenDogMPU004.jpg ‎|300px|thumb|right|The RottenDog "MPU004" Aftermarket MPU with sound section overlay]] 
'''RottenDog MPU9211 and MPU004 Aftermarket MPUs''' 
The RottenDog aftermarket MPU9211 (shown at left) was designed to support all Williams System 9 - 11 games. How well the board works across that great breadth of games is somewhat questionable.

The CVSD used on this board is a CMX639D4 produced by CML Microcircuits. It replaces the 55516 (or 55536) CVSD used at U3 on original System 9 - 11 MPU boards.

The RottenDog aftermarket MPU004 (shown at right) was an earlier design thought to support all Data East and System 11 games. Again, how well the board accomplishes this for Williams games is questionable. A significant source of confusion on this board (like all RottenDog boards with DIP switches) is that the DIP switches are labeled opposite of traditional labeling. That is, set all switches to OFF for Williams games, ON for Data East games.
 
[[File:RDWilliams9211LaterRev.jpg |300px|thumb|left|The RottenDog "System 9211" Aftermarket MPU, later revision]] 
A later revision of the RottenDog 9211 MPU included a second trim POT to adjust the balance between 1408 DAC sounds and 55536 CVSD sounds.
 
====Lamp Matrix====
[[File:WMS Sys9 Lamp Column.jpg|300px|left|thumb|Picture of the lamp column portion of the lamp matrix of a System 9 MPU board. Note that the TIP42 drive transistors were removed from this board.]] 
The lamp matrix is made up of two parts - the lamp columns (drives) and lamp rows (returns). In most cases, the lamp row consists of eight 2N5060 over-current shunt SCR's and eight TIP122 drive transistors, while the lamp column consists of eight 2N6427 predrive transistors (WMS sometimes used MPS-A14 instead) and eight TIP42 or TIP42C transistors. However, there are some instances, as shown in the pic to the left, where the predrive transistors for the lamp columns are 2N6548s. It is unknown why Williams chose to use these transistors on occasion.

The over-current shunt circuit on the lamp row (returns) works by sensing the voltage drop across the 0.4 ohm, 3 Watt resistor on emitter of the TIP122 driver transistor. If a short circuit is present in the lamp row, the short circuit current will result in a higher than normal voltage drop across the emitter resistor. This voltage will trigger the gate of the 2N5060 SCR, causing it to turn on and shunt the base drive to the TIP122 transistor. This will turn off the driver transistor and prevent damage due to excessive current. Note that an RC circuit consisting of a 0.1uF capacitor and 1K ohm resistor is present on the gate of the SCR. This prevents a false trigger of the over-current shunt circuit due to an initial peak current from cold lamp filaments.
 

====Switch Matrix====
=====System 9 Switch Matrix Explained=====
[[Image:System9SwitchMatrix.jpg|300px|thumb|left|The System 9 Switch Matrix circuitry, as found in the Sorcerer manual.]]
General Description

At regular intervals, say 1 every msec or so, the 6808 microprocessor scans the switch matrix. This is done by pulling one switch column to ground, then sensing the switch row return state. Each row on which ground is detected means that the switch at the intersection of the column grounded and the detected row ground, is closed.

Hardware Detail

The 6808 writes the column data to the address location occupied by the 6821 at U15 on the board. This causes the 6821 output registers (PB0 – PB7) to propagate the data to a 74LS244 octal buffer at U45. The 74LS244 mirrors that same data at it's output pins. The data pattern on these output pins will have all bits set to logic “1” except one bit, which will be set to logic zero, or electrical ground. The ground is applied to the base of a 2N3904 transistor (which had been held high by a 4.7K SIP pull-up resistor SR8) where the ground is applied to the switch column (called switch matrix drives on the schematic). 

Closed switches connected to that column will then cause the normally high (via yet another pull up resistor, SR16) gate at a 74LS08 quad NAND gate (U51 and U52) to be pulled to ground. This NAND gate enables the circuitry to detect a switch closure returned via either connector 1J9 or 1J10.

The 6808 then “reads” the row returns by reading from the address space occupied by the same 6821 at U15 used to pulse the column strobes earlier. This time it reads 6821 registers PA0 – PA7.

Again, the processor knows which column it drew to ground, and it knows which rows were caused to be pulled to ground via closed switches attached to the column. From this information, the closed switches can be identified. Genius. Bania: “I'm tellin' ya Jerry, this switch matrix stuff is gold Jerry, it's gold!”.

The switch diode isolates the switch in the matrix. Without this isolation diode, multiple simultaneous switch closures will cause false returns and confuse the processor. A switch diode that is open will always prevent a switch from registering, in the same way that a broken wire or failed open switch would.
 

====Jumper Settings and Locations for System 9 & 11 MPU Boards====

Below are charts of the jumpers on System 9 & 11 boards. Rather than listing the boards by their platform (System 11A/B/C), each chart is listed by the numbers stenciled on the circuit boards.
 

'''5764-10749-00 REV. C (System 9)'''

Typically installed jumpers are W2, W5, W6, W7, W9, & W12.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1 / W2|| Below U12 || Microprocessor Internal RAM Enable. W1 IN, W2 OUT when using 6802, reverse when using 6808 || U12 RAM can be removed with 6802 and W1 installed.
|-
|W3|| || ||
|-
|W4|| || ||
|-
|W5|| Left of U49 || Country jumper. Remove for German factory settings, add for US factory settings ||
|-
|W6|| Below U5 || Along with W7, used to send +12V to opto rows || Typically installed, but not used
|-
|W7|| Below U5 || Along with W6, used to send +12V to opto rows || Typically installed, but not used
|-
|W8|| Below connector IJ9 || Ties resistor network SR15 to +12v ||
|-
|W9|| Below connector IJ9 || Ties resistor network SR15 to +5v ||
|-
|W10|| Below U50 || Installed - sounds from CPU board can be played without speech board attached || Typically not installed, except Strike Zone
|-
|W11|| Below U37 || Used when U19 game ROM 2 is used ||
|-
|W12|| Below U36 || Used to increase U20 game ROM 1 size from 2764 to 27128 ||
|-
|}
 

'''5764-10881-00 REV. - (Typically System 11)'''

Typically installed jumpers are W1, W2, W4, W5, & W7.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below U48 || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}
 

'''5764-10881-00 REV. B (Typically System 11 - Referred to as Prototype System 11a in text above)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Blanking signal to input "D" of U48 LED decoder chip || not present on first pcb revision
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12091-00 REV. - (Typically System 11A)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W12, W13, W14, W16, W17 & W18.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5|| Below U39 & U38 (PIA chip) || Used to apply +5v to SR14 resistor network ||
|-
|W6|| Below U30 & U27 || Used to apply +12v to SR14 resistor network ||
|-
|W7|| Below diagnostic LEDs || Country jumper. Remove for German text and settings, add for English text and settings ||
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| Below U23 || Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed
|-
|}

 

'''5764-12206-00 REV. A (Typically System 11B & 11C)'''

Typically installed jumpers are W1, W2, W4, W5, W7, W8, W11, W14, W16, W17 & W19.

{| class="wikitable"
!Jumper
!Location
!Purpose
!Notes
|-

|W1|| Below U15 CPU chip || Ties crystal to clock input (pin 39) of U15 CPU ||
|-
|W2 / W3|| To the right of U25 RAM chip || Used to increase the ROM size ||
|-
|W4|| Below U31 (to the right of U25) || Used to increase the ROM size ||
|-
|W5 || Above U25 RAM chip || Used with 2K x 8 6116 RAM at U25 ||
|-
|W6 || Above U25 RAM chip || Used with 8K x 8 6264 RAM at U25 || only 2K will be used from the factory
|-
|W7|| Below diagnostic LEDs || Remove for German text, add for English text || This jumper is not used in games with 16 digit score displays. Instead, install the U26 and U27 EPROMs for country and game.
|-
|W8 / W9|| Below U24 (sound CPU chip) || Used to choose what to use as /RST for U24 sound CPU ||
|-
|W10 / W11|| To the right of 3 radial caps in reset section|| Choice of +18v (W10) or +12v (W11) for sound amplifier ||
|-
|W12|| A resistor below U10 PIA || Pull down resistor for E1 (pin 1) and E2 (pin 19) of U11 & U13 address line buffer chips ||
|-
|W13|| A resistor below U16 data line buffer chip || Pull down resistor for /E (pin 19) of U16 data line buffer chip ||
|-
|W14 / W15|| Below U29 || 1ms IRQ signal (W14 in) or 2ms IRQ signal (W15 in) ||
|-
|W16|| Below U27 || Ties XTAL (pin 38) of U15 CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U15
|-
|W17|| To the left of U24|| Ties XTAL (pin 38) of U24 sound CPU chip to ground || Only cut when using Hitachi 6808 or 6802 MPU at U24
|-
|W18 || Below U23 || Used with 8K x 8 6264 RAM at U23 || only 2K will be used.
|-
|W19 || Below U23 || Used with 2K x 8 6116 RAM at U23 ||
|-
|DS1|| Left of U13 || || Marked as DS1 on board (lower of 2 jumpers) - leave out
|-
|DS1|| Left of U13 || || Marked as DS1 on board (upper of 2 jumpers) - leave out
|-
|DS2|| Left of U13 || || Marked as DS2 on board (lower of 2 jumpers) - keep installed up to 11B
|-
|DS2|| Left of U13 || || Marked as DS2 on board (upper of 2 jumpers) - keep installed up to 11B
|-
|}
 

====Combining the System 9 Sound ROM Images====
Pinside user, "Dumbass", has created replacement System 9 MPU boards. One of the new things that he implemented in the board design is a daughterboard that can be mounted to the main MPU, which handles the speech duties. Therefore, the speech board with its sometimes problematic ribbon cable no longer has to be used. However, the sound and speech chip code now has to be combined together on a 27256 PROM, which is used at position U49.

The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).
The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[File:Pad.zip]]. Below is how the code should be concatenated for it to work properly. It is very similar to what is done for the System 9 code to be modified for a System 11 MPU.

Space Shuttle 
Checksum = 0000h


copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Sorcerer 
Checksum = E67Fh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 



Comet 
Checksum = F9CCh


copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 + cpu_u49.128 = cpu_u49.256 

 

====Converting the System 9 ROM Images to work in a System 11 MPU====
It is easy to create System 11 compatible ROM images from System 9 ROMs. 
The DOS/Windows "copy" commands to accomplish this for the System 9 games, are shown below (space formatting added for clarity).

The file [https://www.pinwiki.com/wiki/index.php/File:Pad.zip pad.732] is a special file and is not part of the released ROM images. It is a 4K (4096 Bytes) binary file filled with 0xff. Create it using your favorite hex editor, or download the file here: [[file:Pad.zip]].

The System 11 CPU works out of the box with a 27128 EPROM at location U27. You may choose to double the ROM image, creating a 27256 image so that its size is consistent with the other System 11 U27 ROMs.

Remove jumper W8 and install jumper W9 on the System 11 CPU to enable sound to work properly. System 11 controls the sound reset via software.
 

=====Space Shuttle=====

copy cpu_u49.128 cpu_u21.128 
copy /b pad.732     + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 <=== This command doubles the 128K image into a 256K image

 

=====Sorcerer=====

copy cpu_u49.128 cpu_u21.128 
copy /b cpu_u21.128 + cpu_u21.128 cpu_u21.256 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u22.128 + cpu_u22.128 cpu_u22.256 
copy /b pad.732     + cpu_u19.732 + cpu_u20.764 cpu_u20.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 
copy /b pad.732     + cpu_u19.l2.bin + cpu_u20.l2.bin cpu_u20.l2.128 
copy /b cpu_u20.l2.128 + cpu_u20.l2.128 cpu_u27.l2.256 <=== This command doubles the 128K image into a 256K image 

Sorcerer is the only System 9 pinball game using 2 ROMs which make things complicated for repair. You can use the cpu_u20.128 image in a system 9 CPU jumpered for Space Shuttle or Comet. If you install W12 and remove W11 the CPU will be jumpered for a 27128 EPROM.
 

=====Comet=====

copy cpu_u49.128 cpu_u21.128 
copy /b spch_u7.732 + spch_u5.732 + spch_u6.732 + spch_u4.732 cpu_u22.128 
copy /b cpu_u20.128 + cpu_u20.128 cpu_u27.256 /b <=== This command doubles the 128K image into a 256K image 

 

===Sound Boards===

[[File:WMS Sys9 Speech 2532.JPG|300px|thumb|left|System 9 Speech Board Using 2532 PROMs (from Space Shuttle)]]
[[File:WMS Sys9 Speech Board.JPG|300px|thumb|right|System 9 Speech Board Using 2732 PROMs (from Comet)]] 
The speech board used in the three System 9 games, Space Shuttle, Sorcerer and Comet is essentially the same as the speech board used in System 6/7 games. However the speech board was enhanced during the Space Shuttle run. Four jumpers were added to accomodate either 2532 or 2732 EPROMs. When burning EPROMs, make certain which style of ROM is used. 

[[File:WMS Sys9 Speech Early Later.JPG|300px|thumb|left|System 9 Speech Board - Left unit is from early Space Shuttle, right is from later Space Shuttle]] 
Only the early Space Shuttles use 2532 EPROMs from the factory. Later Shuttles, Sorcerer and Comet use 2732 EPROMs. The later speech board is backward compatible. If using such a board, either 2532s or 2732s can be used for the first two System 9 games (or System 6/7 games), provided that the jumpers are set for the appropriate EPROM. 

In addition to the speech board generating speech sounds, it mixes the sound and speech signals via the potentiometer on the speech board.
 

[[Image:WilliamsSystem11BackgroundSoundBoard.jpg|500px|thumb|left|Background Sound board as found in High Speed]]
[[File:WMS D-11197 Road Kings Sound.JPG|500px|thumb|right|D-11197 Background Sound board as found in Road Kings]]
[[Image:WilliamsD-11297BackGroundSoundBoard.jpg|500px|thumb|left|D-11297 Sound board as found in Pinbot, fully populated]]
[[File:WMS D-11298 Pinbot Sound.JPG|500px|thumb|right|D-11298 Sound board as found in Pinbot. This version only has U4 populated (U19 is not). Uncertain why U19 is needed. Note that the CVSD "lane" of the board is not stuffed.]]
 
[[Image:System_11_Sound_Board.JPG|500px|thumb|left|D-11581 Sound board, not completely populated]]
[[Image:D-11581-F14.jpg ‎|500px|thumb|right|D-11581 Sound board, completely populated]]
[[Image:System11CSoundBoard.jpg|400px|thumb|left|D-11581 Sound Board, Completely Populated, with W10/W11 Jumpers. W10/W11 enable use of 512K sound ROMs as found in all System 11C games like Game Show, Dr. Dude, Pool Sharks, Rollergames, Diner, Radical, and Bugs Bunny]]
 
[[File:WMS D-12238 Jokerz Sound.jpg|500px|thumb|left|D-12238 Sound Board - specific to Jokerz! only]]
[[File:JokerzSoundBoardPinOut.png|700px|thumb|right|D-12238 Sound Board - specific to Jokerz! only - Connector PinOut]]
 
[[File:D11581SchematicIcon.jpg|300px|thumb|left|Use hyperlink at right to open D-11581 sound board schematics]]
[[File:D11581PartsDelta.jpg ‎|300px|thumb|right|Parts missing from partially populated D-11581 sound boards]] 
'''Link to:''' [[media:Audio_schem_11581.pdf|Schematics for the D-11581 sound board]]. 
'''Note:''' The parts shown at right represent the delta from a partially populated D-11581 to a fully populated D-11581. *The value of R13 will vary between 4.9Kohms (or 4.99Kohms) and 10Kohms. If R14 and R15 are 10Kohms, then R13 should be 4.9Kohms (or 4.99Kohms). If R14 and R15 are 20Kohms, then R13 should be 10Kohms.
 

===Power Supply===
[[Image:WMSSystem11PSPreBigGuns.jpg|300px|thumb|left|Pre-Taxi Power/Regulator Board. This power supply has had the header pins replaced and the 5V filter cap at C10 replaced. Note that this board has the 20A fuse for the GI still installed. This indicates that it is an early System 7 board. The fuse and it's holder should be replaced by a wire in all System 9 and 11 games]]
[[File:WMS_PS_5765-09466-01_rev_B.JPG|300px|thumb|right|WMS Power Supply - Revision B (Pinbot) Note that the top fuse holder just below the large 15000uF capacitor is broken on the left side]] 

These power supplies use obsolete parts at Q1 (SDS-201) and Q3 (SDS-202). The PCB print was used from Black Knight through Swords of Fury, with slight modifications. Up until and including Fire!, Q1 and Q3 were the obsolete SDS-201 and SDS-202. Starting with some Fire!, the board uses an MJE15030 at Q1 and an MJE15031 at Q3.

Part numbers printed on an SDS-201 at Q1 may be "6557" or "9057S".
Part numbers printed on an SDS-202 at Q3 may be "MDS60" or "9058S"
 

[[File:EarlyWMSPowerSupplyTraceRoutingErrorCloseUpAnnotated.jpg|300px|thumb|left|A closeup of the corrected trace routing error on a Fire! power supply board.]]
[[File:System11PSSchematic.jpg|300px|thumb|right|WMS Power Supply (High Speed) Schematics.]] 
There was a trace routing error on the original Fire! power supply pcbs. WMS cut the trace and used a jumper to correct the error. This error was corrected in the PCB layout at the start of "Big Guns" game production.
 

[[File:WMS_PS_5765-09466-01_rev_E.JPG|300px|thumb|left|WMS Power Supply - Revision E (Cyclone)]] 
With Big Guns and games after, the solenoid and lamp power power sections were no longer stuffed because they were relocated to the Aux Power board. The GI relay is also missing on these boards because discrete GI relay boards were placed under the playfield and/or behind the backbox lamp insert. By doing this, specific GI strings could be turned on/off versus "all or none" of the general illumination. This later board has the fuses only for display and 5V power. In a pinch, the unstuffed parts could be installed.

Starting with Big Guns, 2 100mA (1/10A) SB fuses are installed just to the left of the power supply in the backbox. These fuses protect the +100V and -100V circuits against shorts. Not all games used 1/10A slo-blo fuses. Some games used 1/8ASB fuses instead. This may have been due to 1/8ASB fuses being more readily available. 

The schematics for this power supply also list part numbers MPSD52 and MPSD02. The equivalent part number for an MPSD52 is a 2N5401. The equivalent part number for an MPSD02 is a 2N5551.
 

[[Image:System 11 Regulator Board.JPG|300px|thumb|left|Taxi and After Power/Regulator Board]]
[[Image:WMSPSSchematic1503015031.jpg|300px|thumb|right|Schematics for Taxi and After Power/Regulator Board]] 
This power supply was used from Taxi thru the remainder of the System 11 game production.
Note that Taxi used an early revision of the board. The placement of some of the resistors and zener diodes in the HV section of that board is different from later boards.
 

===50V Flipper Power Supply Board===
[[File:Williams50VPowerSupply.jpg|300px|thumb|left|50VDC power supply as used in System 11 (nothing) and 11A games (C-9939).]] 
System 11 (nothing) and System 11A games all used the 50V power supply board as pictured at left. This simple board takes 48VAC from the transformer secondary and uses a 35A/400V bridge rectifier to produce about 50VDC. The voltage is smoothed somewhat by a 100uf electrolytic capacitor. The transformer secondary is protected from a short in the bridge rectifier by either a 4ASB or a 5ASB fuse. Be sure to consult the manual for your game for the proper fuse value. Never overfuse a circuit.
 

===Auxiliary Power Driver Board===
At least two different revisions of the Aux Power Board were used in System 11B/11C games, pictured below.
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|400px|thumb|left|Auxiliary Power Board from Space Station (D-11813-552)]]
[[File:System 11 Power.JPG|400px|thumb|center|Auxiliary Power Board from Earthshaker (D-12247-568)]]
 

===Interconnect Boards===
[[File:WMS Space Station Interconnect.jpg|300px|thumb|left|Backbox Interconnect Board from Space Station]]
[[Image:System 11 Lamp Board.JPG|300px|thumb|right|Backbox Interconnect Board from Earthshaker]]
The interconnect board was essentially designed for ease of manufacturing and assembly. When Williams ultimately settled on using the same unit in all games, (give or take some parts here or there), modularity was apparent too. There was no longer a need to build complex, custom wiring harnesses between the CPU / driver board, backbox insert, and playfield. The interconnect board remedied this issue. 

[[File:BanzaiRunInterconnect.jpg|300px|thumb|right|Backbox Interconnect Board from Banzai Run]]Although the first four System 11B games, which include Big Guns, Space Station, and Cyclone use some form of an interconnect board, it wasn't until Swords of Fury when the interconnect board was used as a standard for the remaining System 11 games. The interconnect for Banzai Run (shown on the right) is completely different from anything else used by any game.

The interconnect board used in Swords of Fury uses a different part number, D-12185-559, compared to later System 11 games that used part number D-12313-x (x denotes the game's model number). They are not interchangable. Swords of Fury and Taxi had lane change switches still mounted on the cabinet. With later games lane change switches were removed and two optocouplers at position U2 and U3 (connected to the switch returns) were added to the board. The circuit is essentially the same as was used in early WPC games and enabled elimination of problematic physical lane change switches from the game. Starting with Jokerz, the third coupler at position U1 is used by the game software to check if the A/C relay on the aux power board is working. U1 transmits information back to the MPU as switch 2 on the switch matrix, provided that the A/C has energized.

The early versions of the interconnect board were located on the left side of the backbox and positioned vertically. The more common interconnect boards were located in the backbox positioned horizontally, just below the CPU board. The later board passes the following circuits:
*lamp general illumination circuits
*flipper power and ground
*lamp columns and rows
*switch columns and rows
*flash lamp power

What differentiates the board from game to game are the resistor values used for the flash lamp power circuits. In some cases, some of the resistors are left unpopulated and / or a zero ohm jumper is installed.
 

===Master Display Driver Board===
====System 9 (C-8363)====
[[File:WMS Sys9 SS Sorc Master Display.JPG|300px|thumb|left|C-8363 Early System 9 Master Display Driver Board]] 
This is the same master display that is used on all System 6A and System 7 games and is used on most System 9 games.
 

====System 9 (D-10749)====
[[File:WMS-D-10749.jpg|300px|thumb|left|D-10749 Late System 9 Master Display Driver Board]]
 

This master display board was introduced during the System 9 run and is mostly found in some of the later Comets that were manufactured. The major difference between this master display board (D-10749) and the previous master display board (C-8363) is the D-10749 board replaced the card-edge connectors used on the C-8363 with pin-type connectors.

Any System 9 machine that is wired with card-edge connectors to use a C-8363 master display board can be converted to use a D-10749 master display board by re-wiring to use pin-type connectors.

The following table shows the mapping of the connectors & pins from a C-8363 to a D-10749 to aid in this conversion:

{| class="wikitable"
!D-10749 Connector-Pin
!Function
!C-8363 Connector-Pin
!Notes
|-
|J8-1
|Strobe 16
|J5-14
|
|-
|J8-2
|Strobe 15
|J5-16
|
|-
|J8-3
|Strobe 14
|J5-17
|
|-
|J8-4
|Strobe 13
|J5-13
|
|-
|J8-5
|Strobe 12
|J5-12
|
|-
|J8-6
|Strobe 11
|J5-15
|
|-
|J8-7
|KEY
|
|
|-
|J8-8
|Strobe 10
|J5-2
|
|-
|J8-9
|Strobe 9
|J5-4
|
|-
|J9-1
|Strobe 8
|J5-3
|
|-
|J9-2
|Strobe 7
|J5-11
|
|-
|J9-3
|Strobe 6
|J5-10
|
|-
|J9-4
|Strobe 5
|J5-9
|
|-
|J9-5
|Strobe 4
|J5-8
|
|-
|J9-6
|Strobe 3
|J5-7
|
|-
|J9-7
|Strobe 2
|J5-6
|
|-
|J9-8
|KEY
|
|
|-
|J9-9
|Strobe 1
|J5-5
|
|-
|J10-1
|D1
|J7-4
|
|-
|J10-2
|C1
|J7-2
|
|-
|J10-3
|B1
|J7-1
|
|-
|J10-4
|A1
|J7-5
|
|-
|J10-5
|D2
|J7-8
|
|-
|J10-6
|KEY
|
|
|-
|J10-7
|C2
|J7-7
|
|-
|J10-8
|B2
|J7-6
|
|-
|J10-9
|A2
|J7-9
|
|-
|J10-10
|Comma 1 & 2
|J5-18
|
|-
|J10-11
|Comma 3 & 4
|J5-1
|
|-
|J10-12
|Blanking
|J7-3
|
|-
|J11-1
|GROUND
|J6-5
|
|-
|J11-2
|KEY
|
|
|-
|J11-3
| -100 VDC
|J6-6
|
|-
|J11-4
| +100 VDC
|J6-2
|
|-
|J11-5
|N.C.
|J6-4
|
|-
|J11-6
| +5 VDC
|J6-3
|
|-
|
| -100 VDC
|J6-1
|N.C. on D-10749
|}

====System 11 (Discrete Displays High Speed to Pin Bot and Banzai Run)====
[[File:WMS-D-10877.jpg|300px|thumb|left|System 11 Master Display Driver Board]]
[[File:D-10877WithAlternate7180.jpg ‎|300px|thumb|right|System 11 Master Display Driver Board with UDN7180 "daughter cards". Image courtesy of Aaron Gross.]]
The image at right shows "daughter cards" that replace UDN7180 chips, which were beginning to be become expensive and harder to obtain during the production run. The daughter cards use discrete transistors, much the same way as one version of the older System 3-6 Master Display Panel did. U9, U12, U13, and U14, originally UDN7180s, have been replaced on this board.
 

====System 11A (Millionaire / Early F-14)====
[[File:WMS-D-11414-1.jpg|300px|thumb|left|System 11A Millionaire Display Driver Board]]
This PCB actually came out of an early F-14 where they were recycled. Millionaire had it fully populated with additional lamp covers. The mounting brackets for the later D-11610 display changed so if you get a replacement for your F-14 first check which one is used in your game.
 

====System 11A/B (F-14 to Swords of Fury)====
[[File:WMS-D-11610.jpg|300px|thumb|left|System 11A/B 4 7 Digit Segmented Displays Driver Board]]
 

====System 11B (Taxi and Police Force)====
[[File:WMS-D-12232-2.jpg|300px|thumb|left|System 11B Display Driver Board D-12232-2 for 2 16 digit segmented displays + one external connector for a 7 digit display]]
Taxi and Police Force uses a D-12232-2 master display with J4 ribbon connector stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Taxi and Police Force. You would need to add U3 (6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connector J4. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display.
 

====System 11B (all other WMS 11B/C games)====
[[File:D-12232.jpg|300px|thumb|left|System 11B/C Display Driver Board D-12232-1 for 2 16 digit displays]]
 

====System 11C (Riverboat Gamber)====
[[File:WMS-D-12232-3.jpg|300px|thumb|left|System 11C Display Driver Board D-12232-3 for 2 16 digit displays and 2 connectors for 7 digit jackpot displays]]
Riverboat Gambler uses a D-12232-3 master display with all ribbon connectors stuffed. If it's missing from the game, any other dual 16 digit alphanumeric can be used to make it work with Riverboat Gambler. You would need to add U3 and U4 (both a 6118), resistors R10, 11, 12, 13, 15, 16, 17, 18 (10K) and connectors J4 and J6. Jumper W1 should be added to connect the two center segments g' and m' on the lower display to form one large center segment g'. Jumper W2 should be added to light the comma on the jackpot display. Remove resistors R54, 56, 57, 60, 62, 64, 65, 67. The removal is these resistors makes the lower display essential a numeric display. This display can also be used in Police Force and Taxi.
 

====System 11B/C (all Bally 11B/C games)====
[[File:WMS-Bally-L16-Display.jpg|300px|thumb|left|WMS Bally left side 16 digit Master Display Driver Board]]
 
[[File:WMS-D-12502-1.jpg|300px|thumb|left|WMS Bally right side 16 digit Master Display Driver Board]]
 

===Other Boards===
====Sound Overlay Board (C-13287)====
[[File:WhirlWindSoundOverlayBoard.jpg|300px|thumb|left|Williams "C-13287 Sound Overlay Solenoid Board" as found in WhirlWind.]] 
This relatively simple board was used on Whirlwind only to accommodate 5 additional solenoids (flashers or motors). The board logically sits between the System 11 MPU and the sound board, intercepting data normally sent directly to the sound board, and acting on that data only when specific codes are commanded. The board also relays data not specifically intended for it, on to the sound board.
 

====High Current Driver Boards====
[[File:WMS C-12493 High Current Driver Board.JPG|300px|thumb|left|Williams C-12493 High Current Driver Board from Earthshaker]] 
The high current driver board was used on Earthshaker to drive the shaker motor. It was used on several other Bally/Williams WPC games while designated different part numbers.
 

====Space Station Opto Position Board (C-11872)====
[[File:SpaceStationOptoBoardC-11872.jpg|300px|thumb|left|Williams C-11872 Space Station Opto Positioner PC Board Assembly]] 
This board is unique to Space Station. The "blobs" at Q1 and Q2 (both 2N3906s) in the picture at left are clear silicone caulk used to dampen vibration on the board. 
 

====Flash Lamp Resistor Board (Remotely Located)====
[[File:WMS Flasher Board Pinbot.JPG|thumb|300px|left|Flash Lamp Resistor Board (from Pinbot)]] 
The earlier design of flash lamp resistor board was mounted under the playfield within in the vicinity of the flash lamp circuit(s) that were powered by it. Each board had a maximum of 4 power resistors (2 per flash lamp circuit). The higher resistance resistor is 330 ohm 7 watt, while the lower resistance resistor is 5 ohm 10 watt. The purpose of the larger value resistor is to keep the flash lamp powered with minimal voltage. This keeps the flash lamp filament "warm", which puts less of a strain on the flash lamp. In turn, it is supposed to extend the life of the flash lamp. The smaller value resistor is used as a current limiting resistor which allows the solenoid voltage to be supplied to power the flash lamp. By powering the flash lamps with solenoid voltage, it eliminates the need for an additional, dedicated secondary transformer winding.

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.
 

====Flash Lamp Resistor Board (Centrally Located)====

<center>
<gallery widths=250px heights=380px perrow=3 caption="Flash Lamp Resistor Boards">
File:WMS Big Guns Resistor Board.jpg|<center>D-11814-557(Big Guns)</center>
File:CycloneBigGunsFlashlampBoardD-11814-564.jpg|<center>D-11814-564 (Cyclone)</center>
File:WMS_Space_Station_Resistor_Board_D-11814-552.JPG|<center>D-11814-552(Space Station)</center>
</gallery>
</center>
 

The flash lamp resistor boards were used on early System 11B games prior to the use of the "standardized" interconnect board. The board is located in a very awkward location. It is screwed to the back of the lower cabinet. Big Guns, Space Station, and Cyclone all have this board in this location. 

The resistors on the board "eat current" (limit current) since the 13V #89 flash lamps are wired to coil voltage (about 38VDC). When implementing this board, Williams chose to change the wire colors as the circuit passes through the board. Combined with the generally poor Williams System 11 documentation, this makes it tough to track down problems with non-working flash lamps. On the plus side, the wire wound cement resistors on the board do not fail often, probably due to the location of the board (resistor boards located under the playfield have high resistor failure rates due to heat and vibration). However, they obviously can fail. If there is power at the flash lamp, but grounding the flash lamp transistor does not light the lamp, the associated drive transistor may have failed. 

The flash lamp resistor boards were abandoned after Space Station. Flash lamp circuits and resistors became integrated into the "standardized" interconnect board.
 

====A/C Relay====
[[File:WMS Sys1WMS Sys11 Early AC Relay.jpg|300px|thumb|left|A/C relay board (early design ie. F-14, Pinbot)]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|right|A/C relay placed on aux power driver board starting with 11B games (later design)]] 
Starting with Road Kings, System 11 games make use of what is referred to as an A/C relay. The purpose of the A/C relay was to drive twice the amount of coils and flashers by using half the amount of drive transistors. This process is commonly referred to as "multiplexing". Typically, if the A/C relay was at rest, the "A side" solenoids would engage. When the A/C relay was powered, the "C side" flashers would engage. However, there were sometimes solenoids multiplexed with other solenoids. 

For example, High Speed, which does not use an A/C relay, uses 8 discrete drive transistors to drive solenoids / flashers 1-8. Pinbot, which does use an A/C relay, uses the same 8 discrete transistors to drive solenoids / flashers. However, a total of 16 solenoids and flashers (A side and C side) are driven. By employing the use of an A/C relay, the System 11 MPU / driver board could be used for many more years without a "drastic" redesign. 

Initially, the A/C relay was located on a small circuit board under the playfield for System 11/11A games. Likewise, this A/C relay board did not have Molex header connections. Wires were directly soldered to the circuit board. Once the Auxiliary Power Driver Board was introduced with the System 11B platform (starting with Big Guns), the A/C relay was moved to this board for all subsequent System 11B/11C games.

In the example of the A/C relay shown in the pic on the left, the only way to discern that the A/C relay is the highlighted relay board is due to the wire colors soldered to the board.
 

====Diode Board for Multiplexed Solenoids====
[[File:WMS Sys1WMS Sys11 Early Diode Board. As Found.jpg|300px|thumb|left|Diode board as found mounted to the bottom of the playfield (Pinbot)]]
[[File:WMS Sys1WMS Sys11 Early Diode Board.jpg|300px|thumb|right|Diode board from Pinbot]]
[[File:WMS Space Station Aux Power Driver D-11813-552.jpg|300px|thumb|left|Diodes from diode board moved to aux power driver board starting with 11B games]]

 

====Motor Control Board (D-12045)====
[[File:D-12045.jpg|300px|thumb|right|Williams "D-12045" as found in Cyclone, Jokerz!, Riverboat Gambler and Diner.]] 
This board is used in 4 Williams Games
* Cyclone ... for the random award wheel
* Jokerz! ... for draw poker (the wheel has various cards pictured on it),
* Riverboat Gambler ... for the backbox roulette wheel and
* Diner ... for the clock hands count time.

The board uses a single U-opto to detect the wheel at the "home" position. The MPU implements an "open loop control system" stepping the motor to the desired position while assuming that each step was successful. The game flags an issue with the PCB/motor assembly when the software thinks that the wheel should be at the home position but the opto beam hasn't been broken by the opto interrupter on the back of the wheel.
 

===Flipper Coils===
[[File:WMS Sys11 Flippers.JPG|thumb|left|300px|Serial wound flipper coils as seen on earlier (pre F-14 Tomcat) System 11 / 11A games (pic from Pinbot)]]
[[File:WMS Serial Flipper Schems.JPG|right|300px|thumb|Wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them.
 

[[File:Placeholder.jpg|thumb|left|300px|Placeholder for Parallel wound flipper coils as seen on later (post F-14 Tomcat) System 11A/B/C games (pic from xxxx)]]
[[File:Parallel_Wound_Flippers.jpg|right|300px|thumb|Wiring schematic for parallel wound flipper coils]] 
Later games (starting with F-14 Tomcat) used parallel wound coils, which have 2 diodes on them.
 

System 11 games use different parallel wound 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" |System 11 Flipper Coils
|-
!Part #
!Color
!Strength
!Notes
|-
|FL-11753 || Yellow || Weakest ||
|-
|FL-11722 || Green || Weaker ||24-600 series wound similar strength
|-
|FL-11630 || Red || Standard ||23-600 series wound similar strength
|-
|FL-11629 || Blue || Strongest ||
|}
 

===Accessing Bookkeeping, Settings, and Diagnostic Modes===
[[File:System11CoinDoorButtons.jpg|300px|thumb|right|Example System 11 Coin Door Buttons. The Advance button is missing it's black cap, and yes...that is a bit of soft drink spooge on the bracket.]]
The coin door buttons for system 9 and 11 games are shown at right. The function of the three buttons is (from left to right in the picture)...
*Reset High Score to Date
*Auto Up/Manual Down
*Advance

Function of the Reset High Score to Date is self explanatory.

The Auto Up/Manual Down (AUMD) button is interpreted by the game software in multiple ways. Starting from attract mode, if the AUMD switch is up, pressing the advance button causes the game to enter audits and adjustments mode. If the AUMD switch is down, pressing the advance button causes the game to enter diagnostic mode. With the AUMD button in the up position during many of the diagnostic tests, the next step in the test will be automatically entered. For example, display test will display each digit on the display in turn. Coil test will advance through each coil. A particular step of the test may be paused on by pressing the AUMD button down.

The Advance switch moves the diagnostic, audit, or adjustment to the next step (or previous step if the AUMD button is down, except in diagnostic mode).

When in adjustments mode, the credit button is used to zero, turn off, or turn on features. 
Note: One of the adjustment settings (adjustment 69 on High Speed for example) can be used to clear all of the game audits.

At the end of all diagnostic tests, the game will enter audits next, and then adjustments. To exit diagnostics, audits, and / or adjustments, either advance until the last adjustment, or simply turn the machine off.
 

===Transformer Power Selection Connector===
<center>
<gallery widths=350px heights=400px perrow=2 caption="System 11 Power Selection Jumpers">
File:WMS Sys11 Transformer Power Selection.JPG|<center>Typical power selection connection for a System 11 transformer - 115VAC (from Space Station)</center>
File:System11European220VSelection.jpg|<center>European power selection connection for a System 11 transformer - 220VAC. 1 - Black, 4 - White, 3/6 - Orange. ''Image courtesy of Chuck Sanderson''</center>
</gallery>
</center>
 

==Problems and Solutions==
===Sporadic Problems in General - System 9===
[[File:WMS Sys9 Headers.JPG|300px|thumb|left|Cracked Header Joints and Headers cut too deeply by factory on System 9 MPU]] 
Just like the previous Williams platforms, the System 9 platform is prone to cracked solder joints on the header pins. Likewise, Williams' board manufacturers had some tendencies to cut the header pins too short on the solder side. By cutting the pins too short, the cuts partially go through the solder meniscus. Cutting through the solder meniscus makes a solder joint less reliable, and it may prematurely fail over time. 

By having cracked solder joints and / or cut solder meniscus, sporadic issues may occur. To resolve a cracked solder joint issue, the best approach is to completely remove the old solder, and add new solder to the joint. Due to dirt and contaminants, simply adding solder to the existing joint is not sufficient. If the header pins are cut too short, an attempt to remove the solder and new solder can be made. However, in some instances the only resolution is to replace the header pin connector. It is recommended to use a [http://www.greatplainselectronics.com/Category-79.asp high quality replacement header].
 

===Power Problems===

====Bridge Rectifier Fuses====
[[File:WMS_Sys11_Fuses_Added_Before_Lamp_Solenoid_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. (Pinbot)]]
[[File:System11AdditionalFuses.jpg|right|thumb|400px|The updated schematic (from High Speed) showing placement of additional transformer secondary fusing for solenoid and controlled lamp bridge rectifiers.]] 
A design flaw carried over from the earlier systems was the lack of fuses between the transformer secondary and the bridge rectifiers used for solenoid and controlled lamp power. In theory, if either of these bridges short, the main power fuse in the game should blow. But that is not always the case. If the primary power fuse fails to blow, the wiring between the transformer secondary and the bridge becomes the fuse. The resulting melted wiring is not pretty!

For games before Big Guns, interrupt one of the AC input lines and install a fuse holder with an 8 amp fuse installed (Williams opted to use an 8A normal blo, while Data East chose to install 8A slo-blo fuses). For games after Big Guns, an 8A normal blo fuse is already present between the transformer secondary and the controlled lamp bridge. As for the solenoid bridge, the addition of the auxiliary power driver board added fusing to protect this circuit. The 25V and 50V solenoid bridges were added to this board. Both bridges are fused with 4A slo-blo fuses.

A nice solution for this problem in the Inkochnito Bridge Board.
Surf on over to http://www.inkochnito.nl. Click on the Bridge Board image for more information.
 

====Alternate to the 12 position wafer connection====
[[File:DE-WMS-System11PSCN1Alternative.jpg|300px|thumb|left|The severely burned wafer connector at Data East equivalent of J1 here has been replaced with parts currently available. Pins 5 and 8 are not populated as those connections are not used.]] 
The 12 position "wafer" connector (CN1 or J1 for Williams games), can be replaced with currently available parts, shown at left. The original "wafers" are difficult to find and pricey.
Part number for the alternate connector is Molex 03-09-2121 or 03-09-2122.
 

====Rottendog Power Supply Missing 5v Failure====
If an aftermarket Rottendog WDP011C power supply is missing 5v, and other common causes of a missing voltage have been ruled out, then it's likely that the 5v regulator at U191 has failed. An available replacement is the Texas Instruments PTR08060 5v regulator from [https://www.mouser.com/ProductDetail/Texas-Instruments/PTR08060WVD Mouser] or [https://www.digikey.com/en/products/detail/texas-instruments/PTR08060WVD/1698955 Digikey].

====Rottendog Power Supply - Big Guns & Cyclone GI Comes On, Game Doesn't Boot====
If using the now obsolete Rottendog WDP011A power supply for Williams Cyclone or Big Guns, the +12v jumper may have to be moved from the bottom jumper location to the top. If a Rottendog equipped Big Guns or Cyclone turns on the GI lights, but the game doesn't boot, (only the 5v light on the CPU is lit), this is most likely the reason.

===System 11 MPU Jumpers===
Normally, jumpers on the MPU board do not require modification. The default configuration works for all System 11 game ROMs. However, there are 5 exceptions as follows...

W7 - Language Select Jumper

W7 is used only in games up to Cyclone. Games with 16 digit alphanumeric displays do not use this jumper. If installed, the game automatically reverts to English after losing the content of the RAM. If a different language is preferred, the "adjustments" menu provides an option to change the default language. Only a few early System 11 game ROMs contained multiple languages. For these games, if W7 is removed, the game generally defaults to German text.

Later System 11 games used language specific ROMs at U26 and U27.

W16 and W17 - Hitachi CPU select
[[File:System11Hitachi6802.jpg|300px|thumb|right|A Hitachi processor, installed at U15, with W16 cut (lower right of pic)]]
The W16 jumper, on original System 11 boards, is in a different location and used for backwards compatibility with system 9 boards. There is no need to change it.

On System 11A and later boards:

*W16 is connected to pin 38 (XTAL) of the 6802/6808 at U15, the CPU responsible for most game operation.
*W17 is connected to pin 38 (XTAL) of the 6802/6808 at U24, the CPU for the sound subsystem.

These two jumpers are used to indicate the manufacturer of the 6802/6808 microprocessor since the clock circuit of Hitachi microprocessors is different from the clock circuit of other manufacturers.

If U15 is a Hitachi microprocessor, remove or cut W16.
If U24 is a Hitachi microprocessor, remove or cut W17.
Otherwise, W16 and W17 should remain installed.

A Hitachi microprocessor can be used in System 9 and System 11 (nothing) MPU boards by simply lifting pin 38 out of the socket. Cutting the pin is not recommended since there may be need for that IC in another board.

W5/W6 and W18/W19 - RAM Type Select ONLY FOR SYSTEM 11B AND 11C

System 11B and 11C MPU boards provide the ability to use either a 6116 or a 6264 RAM at locations U25 and U23 (sound subsystem).

For U25...
*install jumper W5, remove W6 to use a 6116.
*Remove jumper W5, install W6 to use a 6264.

For U23 (sound subsystem)...
*install jumper W19, remove W18 to use a 6116.
*Remove jumper W19, install W18 to use a 6264.

Note: Removing both W5 and W6 from a System ll (nothing) MPU or from a System 11A MPU prevents the switch matrix circuitry from working correctly. One instance of this being done resulted in all switches reporting closure, counting backwards from 64 to 1 while in switch level test. Reference [https://pinside.com/pinball/forum/topic/williams-system-11-switch-levels-all-active this] PinSide thread.
 

===MPU boot issues===
====Steps for Repairing a Dead MPU====
[[File:WMSClockandE.jpg ‎|300px|thumb|right|A scope trace of the 4Mhz crystal input at pin 39 of the microprocessor (blue), and "E", the external clock at pin 37 of the microprocessor (amber)]]
Following is an ordered, disciplined process for reanimating a dead MPU board.

#Inspect for Alkaline Corrosion. Abate all corrosion properly before continuing.
#Test for valid 5/12/-12VDC power to the board.
#Verify correct jumpers are installed (or not installed) for Hitachi 6802/8 processors. More info [[Williams_System_9_-_11#System_11_MPU_Jumpers|here]].
#Note and address any error messages displayed upon boot (if any).
#Validate the ROM images.
#Test socketed chips in a known working board or chip tester.
#Verify a proper (4Mhz) clock signal to the 6802/8 processor at pin 39.
#Verify a proper (1Mhz) external clock signal at pin 37 of the 6802/8.
#Verify the reset circuitry is providing a valid "low and then high" reset signal at pin 40 of the 6802/8. Note that replacing the original reset circuitry with a modern reset generator will lengthen the time until the signal transitions to high. This is normal, and helps with debugging as the signal can be seen much easier.
#Use a logic probe to test for activity on the IRQ (pin 4), Address and Data pins of the 6802/8.
#Use a logic probe to ensure that the following bus buffer chips are correctly mirroring the input signals to the output signals:
##System 9: U1, U2 and U3 (address, R/W, and external clock), and U23 (data)
##System 11: U11 and U13 (address, R/W, and external clock), and U16 (data)
#Install Leon's test ROM to ensure that each 6821 PIA is receiving the correct chip select and data to produce valid outputs at pins 2 through 17. More information regarding use of Leon's test ROM can be found [[Leon_Borre_Williams_System_11_Repair|here]].

====Normal Game Boot Behavior====
[[File:WMS Sys9 Boot Display.JPG|300px|thumb|left|The 7-Segment diagnostic display on a System 9 MPU]] 
Normal MPU boot behavior for System 9 is to show a "0" in the diagnostic display on the MPU. The "0" will light during boot up, and continue to stay lit, as long as the game is on. 

[[File:Diagnostic7Segment.jpg|300px|thumb|left|The 7-Segment diagnostic display on a System 11(nothing) MPU]] 
Normal MPU boot behavior for games with a 7-segment display on the MPU is to show a "0" in the display. The "0" does not go away. The "0" will continue to be displayed under normal boot conditions. 

[[File:DiagnosticLEDs.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs as found on a System 11A, 11B, and 11C MPUs]] 
Normal MPU boot behavior for games with 3 LEDs instead of the 7-segment display on the MPU is for the "+5 VDC" LED to light first and stay on, then a split second later, the blanking LED will light and stay on. At the same time that the blanking LED lights, the diagnostic LED will begin to blink at a fairly rapid pace with a 50% duty cycle (equal durations of the LED being on then off). The blanking LED will continue to remain on. 

[[File:LEDDiagnosticsIn7SegmentGame.jpg|300px|thumb|left|+5 VDC, Diagnostics, and Blanking LEDs driven by game software expecting a 7-segment display as in High Speed]] 
If a System 11 MPU with 3 LEDs is installed in a game whose original board contained the 7-segment LED diagnostic display first introduced with the System 7 board set, the status of the 3 LEDs won't help much. The game software is attempting to display a "0" (assuming your game boots correctly) on a 7-segment display. Since the board contains just the three LEDs, the MPU circuitry merely lights all three LEDs as shown in the picture at left.
 

====MPU Boot Error Codes====
MPUs used in System 9 and 11(nothing) games display a code on a 7-segment display if an error is detected during boot. MPUs used in System 11A, 11B, and 11C games use the Diagnostic LED to blink a "codes". 

=====System 9 Games=====

The following table lists the error codes displayed on the System 9 MPU 7-segment display. 

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U18 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6808 processor's ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U20 Game ROM 1 faulty
|-
|<center>3</center> ||  U20 Game ROM 1 faulty
|-
|<center>4</center> ||  U19 Game ROM 2 faulty
|-
|<center>5</center> ||  Blanking signal stuck, coin door closed, memory protect circuit faulty, or the U18 CMOS RAM faulty
|-
|<center>7</center> ||  System failure. Occasionally, the following components can contribute to this problem: U21 (4MhZ crystal), components in the IRQ circuit, broken leads or failed C9 (22uF) in the reset section, or loosely seated ICs on the CPU board. Note that boot code "7" is the hardware default and characteristic of the CPU "reset" signal not complying with the proper low-to-high spec at pin 40.
|-
|<center>Other or no indication</center> ||  U20 Game ROM 1 faulty
|}

If the game is locked up, there may be a bad power supply. The 5 volt logic supply is the first one to check. Then, check the 12 volt supply, which is used to reset the CPU chip. Test for both DC (correct voltages) and AC (too much ripple on the DC circuit).

=====System 11(nothing) Games=====
The following table lists the error codes displayed on the System 11(nothing) MPU 7-segment display. 

Note: These error codes assume that either High Speed, Grand Lizard, or Road Kings ROMs are installed since those were the only three games shipped with this version of the MPU board containing the 7-segment display. Later System 11 MPU boards replace the 7-segment display with 3 discrete LEDs that indicate 5V presence, diagnostics execution, and blanking status. While the System 11(nothing) MPU board works fine with other/later game ROMs, the 7-segment display with later game ROMs doesn't provide useful information other than some confidence that the software is running correctly. With later game ROMs installed and the MPU booting properly, the 7-segment display will appear to alternate rapidly between "0" and "7" (as fast as the "Diagnostics" LED would be flashing in a System 11A through 11C MPU board).

{| class="wikitable"
!Code
!Description
|-
|<center>0</center> ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  CPU board locked up. Possible cause is memory protect circuit and U25 CMOS RAM "stuck bits".  That is, an actual failure of the CMOS RAM chip or the 6802 processors ability to communicate error free with the RAM.
|-
|<center>2</center> ||  U27 Game ROM checksum failure
|-
|<center>3</center> ||  U26 Game ROM checksum failure
|-
|<center>4</center> ||  not used
|-
|<center>5</center> ||  Blanking signal "stuck", or the coin door is closed, or the memory protect circuit is faulty, or the CMOS RAM at U25 has failed.
|-
|<center>Other or no indication</center> ||  General system failure. Check the 5VDC power supply as well as the integrity of game ROM 2 at U26.
|}

A zero displayed during Memory Chip Test (using the CPU board switch SW2) indicates that the blanking circuit is NOT functioning properly. 

An eight displayed during memory chip test (using the CPU board switch SW2) indicates that the blanking circuit is functioning properly. 

=====System 11A, 11B, 11C games=====
The following table lists the number of blinks of the DIAGNOSTIC LED, the error message that might be displayed, and the explanation (Source: Williams System 11A game manual. with embellishment). 
[[File:YT.png]] A video demonstrating an MPU indicating a U10 failure (8 blinks) can be found [https://youtu.be/Rhho5nO3YLU here].

{| class="wikitable"
!Code
!Message
!Notes
|-
|<center>0</center> ||  no message ||  Normal game boot with no problems detected. The game should be in attract mode.
|-
|<center>1</center> ||  U25 RAM FAILURE  ||  The RAM at U25 could not be used properly. This means that the RAM failed a read/write test at power up.  The game will remain in the current state and no other tests are performed until the game is turned off, then back on.
|-
|<center>2</center> ||  MEM. PROT. FAILURE  ||  This message means that either:    a) the Coin Door may be shut,    b) the Memory Protect Switch may be stuck in the ON position,    c) the memory protect logic is protecting the memory, or    d) a U25 RAM failure is occurring.
|-
|<center>3</center> ||  U51 PIA FAILURE ||  The PIA at U51 has failed.
|-
|<center>4</center> ||  U38 PIA FAILURE ||  The PIA at U38 has failed.
|-
|<center>5</center> ||  U41 PIA FAILURE ||  The PIA at U41 has failed.
|-
|<center>6</center> ||  U42 PIA FAILURE ||  The PIA at U42 has failed.
|-
|<center>7</center> ||  U54 PIA FAILURE ||  The PIA at U54 has failed.
|-
|<center>8</center> ||  U10 PIA FAILURE ||  The PIA at U10 has failed.
|-
|<center>9</center> ||  IRQ FAILURE ||  The interrupt request line is not working normally. It may be missing, stuck, too fast, or too slow.
|-
|<center>10</center> ||  U27 ROM FAILURE ||  U27 failed checksum (test 11 is skipped).
|-
|<center>11</center> ||  U26 ROM FAILURE ||  U26 failed checksum.
|}

All of the above failures (except #9) may mean that the device has failed but it may also mean that the 6802 microprocessor is unable to communicate adequately or properly with the device. For example, if the CPU is attempting to checksum the game ROM at U27, but one of the 8 data lines leading to U27 has been severed, the wrong data will be received by the microprocessor and the checksum test will fail even though the ROM is perfectly fine.

An U25 RAM failure can occur without actual 6116 RAM failure. One of the most common reasons why U25 RAM failure occurs is lack of power to the RAM chip. If the D1, 1N5817, diode shorts open, logic power will no longer have a pathway to the U25 RAM. However, if the D2, 1N4148, blocking diode is fine, and the battery holder and batteries are fine, power will be retained by the U25 RAM. Although, the batteries will die prematurely if D1 has shorted. Another reason why U25 is no longer powered by the +5VDC logic power is due to a severed trace either caused by a blunt object or battery corrosion.

An interesting side effect to the U25 RAM failure blink code is that the blanking LED will blink 10 times after the single blink from the diagnostic LED.

===== U51, U27, and possibly other boot message causes =====
[[File:System11SocketWornOut.jpg|300px|thumb|left|This OEM System 11 MPU socket is tired, worn out, and no longer provided solid contact with the ROM chip legs.]] 
System 11 MPUs booting with error codes, blinks, or messages on the display may need new sockets for the game ROM(s). In the picture at left, it's easy to see light right through the socket holes (note the brown background vs the white background). The metal female connections have fatigued over time and are no longer providing a solid mechanical connection to the ROM chip legs. Removal and replacement with a quality dual wipe or machine pin socket is advised.

This situation can cause a wide variety of boot problems including complete failure to boot, "U27 ROM failure" message, "U51 failure" message, etc.

Of course, the root cause could be due to many other reasons. The fairly complicated chip select logic outlined on sheet 4 of the System 11 MPU schematics could be the cause. The best way to attack the problem is with a logic probe, ensuring that the various chip select gates are yielding the intended logic states.
 

=====Five "Knocks"=====
Sometimes when turning a system 11 game on, the knocker will fire 5 times, causing most folks to wonder, "what the hey"?. All that knocking is designed to call the operators attention to a potential switch issue. Like the "credit dot" in later Williams games, including System 11 games that support the dot character, these 5 knocks mean that the game hasn't detected the closure of a particular switch (or switches) in a certain number of games. A message will be displayed indicating which switch or switches to examine.

Usually, this is an indication of a failed switch. Most switches get closed during the normal course of game play, long before the game's software counts up to the limit of "games played without closing each switch" and issues this indication.

To address this issue, use the coin door diagnostic panel buttons to enter switch edge test. Manually close the switch. If a switch closure is indicated, either normal game play failed to close the switch (you're not a very good player), or the switch is dirty. Closing a switch with your finger is different than closing a switch with a ball. Your finger generally pushes more firmly on the switch contacts. Clean the switch by dragging an old business card or piece of paper between the switch contacts while pinching the switch blades together with your fingers.

Caution: do not attempt to adjust switches with anything metal while the game is turned on. You will eventually short coil or lamp power to the switch matrix, damaging the MPUs switch matrix circuitry.

If closing the switch manually doesn't register in switch edge test, see the "switch problems" section of this Wiki.

=====System 11 "Adjust Failure" and "Factory Setting"=====
[[File:AdjustFailureMessage.jpg|300px|thumb|left|The typical "Adjust Failure" message on a System 11 game, coin door closed.]] 
The "Adjust Failure" message seen in the picture at left occurs when the game software can't make sense of the information contained in the battery backed RAM at U25. This could be because the RAM has failed, but this is unlikely. The vastly more common reason is that battery backup power has been interrupted to the games battery backed RAM because either the batteries are not installed, dead, or dying. Hopefully, they haven't made a mess of the board by leaking alkaline. See below. "Adjust Failure" is displayed under these conditions when the coin door is closed. 

Note that on some games (not certain if all) which use two 16-digit alpha-numeric displays, the message displayed will actually read "AJSTMENT FAILURE".
 
[[File:FactorySettingMessage.jpg|300px|thumb|left|The typical "Factory Setting" message on a System 11 game, coin door open.]] 
If the coin door is open under these conditions, the message "Factory Setting" is displayed.
 

=====Testing for Battery Backup Power at the RAM (U25)=====
[[File:U25_Ram_Test.jpg|300px|thumb|right|Game off. Meter set to DC volts. Black lead on game ground. Red lead on RAM pin 24.]] 
Testing for power at the RAM chip is easy.

#Set DMM to DC volts (or on less than 20V if not using an auto-ranging meter)
#Game off
#Black lead on backbox ground
#Red lead on pin 24 of the RAM as shown at right

Three AA batteries normally provide 4.5VDC. If you are reading some voltage, but not quite 4.5VDC, the batteries need to be replaced...and don't forget to move them off of the MPU board while you are at it.

Other causes for low or no battery backup power to the RAM chip are:

#Failed diode D2. This blocking diode normally prevents the 5VDC source from "charging" the alkaline batteries. D2 is a 1N4148.
#Failed diode D1. This blocking diode normally prevents the 5VDC battery backup power from powering parts of the board other than the RAM chip. In this case, the batteries will deplete rapidly. D1 is a 1N5817.
 

==== 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!]] 
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 board.

For System 9 MPUs cross-connected, the damage can include, but is certainly not limited to, U41, U9, the game ROMs, and one or more 6821s. 

For System 11 MPUs cross-connected, the damage can include, but is certainly not limited to, U11, U31, U34, U35, U36, U44, the game ROMs, and possibly the 6821s.

[[image:YT.png]] A YouTube video demonstrating the repair of a System 9 MPU that was damaged in this way can be found [https://youtu.be/uoYKRJFnm-I here].

[[image:PinSideLogo.png]] An excellent disciplined approach to repairing a System 11 MPU damaged in this way can be found on PinSide [https://pinside.com/pinball/forum/topic/i-fried-my-system-11-cpu-board-now-what#post-7564730 here].
 

==== Relocating the battery from the System 9 MPU board ====
[[File:Leaking_Battery.jpg|200px|thumb|right|Yikes! What a pity...]]
Relocating the 3 AA batteries used to retain settings across power cycles to a location far away 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" in the credit/match display is seen when the game is turned on, the game is in audit mode versus attract mode. Below are several reasons why the game has defaulted to audit mode.
* The batteries have failed and need replacing.
* The battery voltage is not reaching the U18 (5517-2) RAM. Check pin 24 of U18 for approximately 4.3v with the power on and 3.9v with the power off. Lack of battery backup power could also be due to an open D3 (1N4148) blocking diode. This diode is used to keep the CPU's logic power from charging the batteries.
* Blocking diode D2 (1N5817) has shorted, and the batteries are trying to run the MPU board when the game is off.
* There are other problems, such as a faulty 5517-2 RAM.

Simply removing the batteries will not allow a game to 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 (obtained by setting maximum credits to 0), or high scores. However, a System 9 game will boot, and is still playable with the lack of batteries. To complete the boot sequence into attract mode, open the coin door, switch the game off, and then quickly back on. The game should leave audit mode, and go into attract mode. Credits would need to be added from the coin door, and if necessary, settings would need to be changed before starting a game.

The best 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) components of the MPU board. 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. You can easily remove the battery pack from the board. Plus, if the batteries are forgotten, and do leak, the MPU board will 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. This will prevent the batteries from being charged and 'cooked' by the game if blocking diode D3 on the MPU board fails. Keep in mind that adding a secondary diode to this circuit will decrease the voltage passing to the RAM memory by .5 to .7 volts (the typical voltage drop across a diode) if D3 is still good. 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. 

[[File:WMS Sys9 remote bat.JPG|300px|thumb|left|Williams System 9 MPU Board]] 
On the System 9 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" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save you some headaches.
 

[[File:WMS Sys9 D2 D3.JPG|300px|thumb|left|D2 and D3 Diodes Highlighted on a Williams System 9 MPU Board]] 
Since the MPU board is already out, another good practice is to check the D3 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 prematurely, (rather quickly). In worse cases, the new batteries can even leak or explode if charged. Testing the D3 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D3 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 5517-2 RAM memory, if D3 is still good. 

==== Relocating the battery from the System 11 MPU board ====
[[File:RemoteBatteryHolderSystem11.jpg|300px|thumb|left|A remote battery holder installed on a System 11 MPU. The purple wire is positive.]]
 

==== Installing NVRAM instead of batteries ====
[[File:NVRAM DIP.JPG|300px|thumb|left|RAMTRON DIP NVRAM installed on a System 11B board (Cyclone)]]
[[File:NVRAM SMT Adapter.JPG|300px|thumb|right|SMT adapted NVRAM installed on a System 11B board (Transporter The Rescue)]] 
Like most other pinball mpu boards, the battery-backed RAM can be replaced with a non-volatile memory RAM (NVRAM). Replacement RAM that can replace existing 6116 or a 6264 SRAM will be needed. DIP versions are becoming scarce, but there are other solutions available that use surface mount equivalents on a small circuit board that plug into the RAM's socket. Unfortunately, U25 is soldered in on System 11 boards from the factory, and would need to be removed to replace with NVRAM.

If installing any version of 6264 NVRAM on an 11B or 11C board, jumper W5 (located just above U25) needs to be moved to jumper W6. This jumper has a completely different purpose on 11 and 11A boards. 6116 NVRAM will have to be used with 11 and 11A boards, or else modification with wire wrap will be necessary. If 6116 NVRAM is used on 11B or 11C boards, jumper W5 does not have to be chaged.

There are several vendors who sell surface mount NVRAM on an adapter board. The adapter in the picture shown on the right was purchased from [http://www.pinitech.com/products/cat_memory.php Pinitech].
 

It has been documented that some variants of DIP NVRAM may need to have diode D1 replaced with a jumper or jumped around the diode, in order for the game to boot successfully. D1, a 1n5817 diode, has a very low forward voltage drop (about 0.2 volts) vs. the normal 0.4-0.6 volts most other diodes have. If replacing U25 with the memory RAM, some memory RAM will not unlock and allow writes until the voltage is 4.8 volts or so. The 1n5817 D1 diode is just enough to prevent some memory RAMs from allowing writes. To solve this, solder a jumper wire around the D1 terminals, or remove D1 entirely and replace with a jumper. Surface mounted NVRAM on an adapter board is not susceptible to this problem.
 

====Installing a Memory Capacitor Instead of Batteries====
[[File:WMS Sys11B Mem Cap.jpg|300px|thumb|left|Memory Capacitor Added to a System 11B MPU Board. The circled areas show an added jumper for the cap's negative terminal to ground and a jumper added in place of the blocking diode.]]
[[File:System11SuperCapInstalled.jpg|300px|thumb|right|An alternate method of adding a SuperCap. This style cap has two leads on the bottom of the cap. The negative lead of the cap is connected to battery ground via the red jumper wire. The necessary jumper across D2 is circled.]]
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 greatly reduced compared to a rechargeable battery. When the game is turned on, it is charging the capacitor. When the game is turned off (this is where the memory cap slightly differs than a rechargeable battery) 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. 

When installing a memory cap, two things will have to be done. It will be necessary to add a jumper to tie the negative lead of the cap to ground or positive lead to the non-banded side of the blocking diode. The picture to the left shows a jumper added to tie the negative lead of the cap to ground on a System 11B MPU board. Installation on System 11, 11A, and 11C boards is similarly performed. Secondly, the 1N4148 blocking diode (D2) will have to be removed, and replaced by current limiting resistor. A value from 100 ohms to 270 ohms will work. Once the capacitor is installed, and the board installed back in the game, it is a good idea to leave the game on for 15-20 minutes to allow the game to initially charge the capacitor to full capacity. After that, turning the game on monthly for about 10 minutes to allow the cap to recharge is a good idea. 
Note: Both photos show a jumper installed in place of the blocking diode. It is recommended that a limiting resistor be installed instead. 

Note: It has been determined that memory capacitors are not the most effective way to retain memory on System 11 games, if the game will not be turned on for long lengths of time.
 

==== Repairing Alkaline Corrosion ====
[[File:System11MPUDelicateTraces.jpg|300px|thumb|left|Closeup of the delicate traces under the battery holder of a System 11 MPU. Luckily, these cleaned up nicely.]]
[[File:System11CorrosionCropped.jpg|300px|thumb|right|Closeup of traces under the battery holder. Corrosion (darkened spots) has invaded beneath the solder mask (green coating) and is beginning to eat away at the copper traces.]] 
As can be seen at left, the traces on System 11 MPUs are very small. Not much alkaline damage is required to eat completely through these delicate traces. Unfortunately, there are a great many of these traces under the battery holder, and in a very vulnerable position to alkaline damage.

Also, to the left of the battery holder is the reset section of the MPU. That section is, on balance, much easier to repair than the delicate traces under the battery holder and at the 6821 PIAs immediately under the battery holder.

The advice often dispensed to deal with alkaline corrosion is to scrub the affected area with an acid such as vinegar, rinse with water, and then rinse again with isopropyl alcohol. This might work for light surface alkaline corrosion.

Unfortunately, often the alkaline will eat into traces beneath the solder mask or beneath chips. This dictates desoldering affected chips to remove the corrosion and repair traces. The alkaline interacts chemically with the solder making it very difficult to heat. Desoldering from the (presumably undamaged) back side of the board is much easier. Scuffing the alkaline damaged solder with a wire brush to remove the surface layer of damage is also helpful.

Once all damaged components have been removed, sand the affected area carefully with your choice of fine grit sandpaper. 220 grit works well. The objective is to remove the corrosion completely without destroying additional traces. All corroded areas must be addressed.

Next, rebuild traces as necessary. Corrosion tends to sever traces where the trace meets the solder pad of a part. Strong magnification and bright lighting helps. Either tin or conformal coat the bare copper and then reinstall parts.

[[File:WMSSystem11AlkalineDamage-1-Annotated.jpg|300px|thumb|left|Another closeup of the delicate traces near the battery holder of a System 11 MPU. These traces are too far gone for a repair to be considered reliable.]]
[[File:ReplacingSRCPartsSystem11.jpg|300px|thumb|right|A 9 pin, 4.7K bussed resistor network replacing SRC5. Pin 1 is on the right]]
[[File:System11AlkalineCorrosion.jpg|300px|thumb|left|A closeup of alkaline damage that has crept under the solder mask (the darker traces). Eventually, this corrosion will eat completely through the trace, making the board unreliable.]]
[[File:TypicalSRC.jpg|300px|thumb|right|The OEM resistor/capacitor network.]]

At the top of the board are a few "SRC" parts. These are 10 pin resistor/capacitor SIPs. The OEM part connects each driver line to a 4.7Kohm pull-up resistor connected to 5VDC. This guarantees that the signal is held at logic high until the PIA grounds the signal. The OEM part also connects each driver line to a high frequency noise filter capacitor (470pf). These parts are no longer available. A completely acceptable substitute is a 9 pin bussed, 8 resistor network (4.7Kohms) at positions SRC1 - SRC5 and SRC7 - SRC9. This part provides the pull-up resistor. In practice, the high frequency filter capacitor does not impact the displays.

The part is installed as shown in the picture at right, with pin 1 of the part connected to the right side which is labeled pin 1 in the board silkscreen. A 10 pin (9 bussed resistors) part may be used ONLY if the left most pin is clipped and not connected to ground.

An image of the original OEM part is shown at right.

Another example of alkaline corrosion can be seen in the picture on the left. This damage can be cleaned up, retinned, and the board placed back in service.
 

====Blanking Signal Stuck Low or Pulsing====
The blanking signal is a failsafe interlock with critical game functions including the display, sounds, lamp matrix, and solenoids. It prevents operation of each of these game features to protect the game circuitry in the event of a system failure. For instance, if the MPU is not running, and the lamp matrix is stuck on at a particular row or column, those parts will heat up quickly, and at the very least damage that circuitry. Coils remaining locked on could cause even larger damage to the game.

Each of the game functions listed above require the blanking signal to be high (not pulsing but always high) to operate. As an example, the solenoid driver circuitry logically "ands" the blanking signal with solenoid commands using a 7408 AND gates (at U17, U18, U19 and U20).

Lack of blanking, with the blanking LED never lighting, means that the game program is not running. It either never started running, locked up due to an invalid ROM image or a problem with the data, address, control, or chip select signals on the MPU, or detected a problem with the RAM memory. 

[[File:System11Blanking.jpg ‎|thumb|left|300px|C58, a timing element for the 555 timer. Image Courtesy of Chris Hibler.]] 
In rare cases, C58 can fail. C58 holds the input to the 555 timer high between pulses from the display circuitry. This causes the blanking signal to pulse. A pulsing blanking signal can manifest in missing digits on the display, some lamp columns not being turned on, and possibly other issues. C58 is a 1uf tantalum capacitor. If the blanking signal is pulsing, replace C58. 

[[File:WMSSystem11Blanking.jpg|thumb|right|300px|Williams System 11 CPU Blanking Circuit. Image Courtesy of Chris Hibler.]]

The blanking circuit explained

#A properly executing CPU will send data to the display 6821 PIA at U51 (pin 4) at regular intervals (every 2.8 msec).
#This action causes PA2 at pin 4 of the 6821 to pulse high periodically. The DE schematics call this signal "TG". It is merely called "blanking" in WMS schematics.
#The signal is inverted by the 7404 at U36, in at pin 13, out at pin 12.
#The coupling capacitor at C57 can be ignored. These ceramic caps rarely fail.
#The signal is applied to the base (pin 2) of a 2N4403 at Q50 and to pin 2 of the 555 timer at 1C.
#The 555 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 U51, the output of the 555 timer at pin 3 (and 7) will go low, which invokes blanking and protection of the system circuitry.

For the longer, more detailed explanation, [http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb75.pdf Stern service bulletin 75] provides the "Blanking Circuit Theory of Operation" for Data East MPUs which are identical to Williams MPUs with respect to the blanking circuit.

When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
#low
#pulsing at the same rate as the 6821 PIA at U51, pin 4
#high
#high
#pulsing very rapidly. i.e. "ticking"
#high
#high

If [https://www.pinwiki.com/wiki/index.php/Leon_Borre_Williams_System_11_Repair Leon's System 11 test ROM] runs correctly on an MPU, this guarantees that all data, address, and control signals are working correctly. If blanking doesn't go high with a game ROM installed, ensure that the ROM images are valid. This is by far the most probable once Leon's ROM runs correctly.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (System 9)====
[[File:System9ResetGenerator.jpg|thumb|left|300px|Reset section of a System 9 MPU board.]]
[[File:WMSSystem9ResetSection.jpg|thumb|right|300px|The image above shows the single jumper and the exact minimum parts required when using a reset generator on a System 9 MPU. The three electrolytic caps (all 100uf/25V), two inductors, and 5 ceramic caps (all .001uf labeled "102") are part of the 5, 12, and -12 volt power filtering circuitry. The D2, 1N5817 diode isn't needed if an NVRAM is used instead of a SuperCap or remote batteries. However, a jumper must be installed at D2 to power the NVRAM.]] 
The reset section of the System 9 MPU is almost identical to the System 11 reset section. As such, a modification similar to the mod outlined below can be performed on System 9 boards too.

#Remove resistors R6, R8, and R12. Really, all but R6 can simply be clipped off. One through hole at R6 will be used later.
#Remove transistor Q4
#Install a reset generator (MCP120-460GI/TO) where Q4 was removed. Orient the reset generator the same way that Q4 was oriented, matching the PCB silkscreen.
#Add a jumper from the upper leg of where R6 was removed (oriented as shown in the picture, upside-down from game installation) to the via that is about 1/4" southeast of the R6 connection.

That's it. Most of the rest of the reset circuit can be removed, but this provides no advantage since those parts are already "out of circuit" with this modification. After this modification is performed, the MPU board will no longer need the +12v to successfully boot. However, +12v is still necessary to power the sound amplifier on the board.

[[File:System9ResetMinimum.jpg|thumb|left|300px|Another image of the bare minimum part requirement when using a modern reset generator. The three electrolytic caps are all 100uf/25V. Note that the right most electrolytic cap is oriented backwards from the other two. The 5 ceramic caps are all .001uf and are labeled "102". These are sometimes called 1000pf ceramic caps.]] 
The MCP130 reset generator variant, with an internal 4.7K ohm resistor can be used too, but it isn't necessary. This is because the resistor at R170 provides an external 4.7K ohm pull up for the /RESET line.

Note that the reset generator has a longer reset delay than the OEM circuitry. At boot, the 7 segment LED will seem to show a "7" for a fraction of a second. It will turn to a "0" and remain "0" after that, assuming that the board is booting properly.
 

[[File:System9Inductor1.jpg|thumb|left|300px|Factory installed "zero ohm jumpers" where inductors are normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]]
[[File:System9Inductor2.jpg|thumb|right|300px|Factory installed "zero ohm jumper" where an inductor is normally installed on a System 9 MPU board. Image courtesy of John Wart Jr.]] 
Note that some System 9 MPUs shipped from the factory with zero ohm jumpers installed instead of inductors (see images left and right). When repairing alkaline corrosion, it's completely acceptable to replaced damaged inductors with jumpers.
 

====An Alternative to Rebuilding the Reset Circuit / Using a Reset Generator (All versions of System 11)====
[[File:WMS Sys11 Reset Section.JPG|thumb|left|300px|Reset section of a System 11A MPU board. Components to be removed are circled.]]
[[File:WMS Sys11 Reset Gen.JPG|thumb|right|300px|Reset section with reset generator and jumper installed.]] 

There is an alternative to the stock reset circuit on all versions of the System 11 MPU boards. A reset generator can be installed. Since the reset section of all versions of the System 11 MPU board is susceptible to battery damage, this is a very easy, and minimalistic way to rebuild the reset section. To do so, 4 components will need to be removed and a jumper installed. The following work will have to be done.

#Remove the Q39 transistor.
#Remove the following resistors - (from top to bottom as installed on the board) R58, R60 (these two are just below the Q39 transistor), and R69.
#Add reset generator MCP120-460GI/TO (also used on Data East MPUs) where Q39 was. Orient the reset generator in the same manner Q39 was oriented (pin 1 of reset generator will install in the bottom through hole). In other words, the "flat" side of the reset generator will face to the right.
#Add a jumper between the right pad of R58 and the right pad of R60 (both resistors have been removed).
 

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. However, +12v is still necessary for the sound section of the MPU on most boards, except the 11B and 11C variants. Likewise, any of the other components in the reset circuit can be removed if desired. Please consult the System 11 MPU board BOM and schematics to determine exactly what components can be removed. The MCP120-460GI/TO reset generator can be purchased from Great Plains Electronics. The MCP130 variant with an internal 4.7K ohm resistor can be used, but it is not necessary. This is because resistor network SR19 pin 3 is an external 4.7K ohm resistor used to pull up the /RESET line.

Below is a prime example of where a reset generator is very handy. The amount of components replaced are reduced from 15-20 to 1. Note that because this was an 11B board (also true for 11C boards), there is no sound amplifier on the board. Hence, the +12v is not needed at all, and none of the parts related to the +12v were repopulated. If this were an 11(nothing) or an 11A board, the +12V inductor (can be replaced by a simple jumper), the W10/W11 jumper, and associated capacitors (C27, C28, and C29) would need to be populated.

<center>
<gallery widths=330px heights=210px perrow=3 caption="A Prime Candidate for Using a Reset Generator (11B MPU Board Shown)">
File:Sys11 Battery Rot.JPG|Battery alkali leeched into the reset section.
File:Sys11 Battery Rot WIP.JPG|Components removed, affected traces and pads cleaned and treated.
File:S11ResetSectionAnnotated.png|Components repopulated. The image above shows the single jumper and the exact minimum parts required when using a reset generator.
</gallery></center>

[[File:System11MinumunResetSection.jpg|thumb|right|300px|Another image showing the single jumper (string tied to it) and the exact minimum parts required when using a reset generator (System 11B/11C). System 11 (nothing) and System 11A must retain a few more parts.]] 
In the above gallery pics, note that some components in the reset area had to be reinstalled. These components are in the area of the reset section, but are not part of the reset circuitry. They are actually related to the game RAM, enabling CMOS power to reach the RAM and to control pin 18, the chip enable pin of the RAM. Without these parts, the MPU will not successfully boot. Instead, there will be a '''single blink code''' from the diagnostic LED indicating a U25 RAM error (a "1" will display on boards with the 7-segment display). If the game display is connected to the MPU board, a "U25 RAM ERROR" message will be displayed.
*D1 - 1N5817 diode
*Q40 - 2N3904 transistor (a 2N4401 was used in this case)
*R64 - 1 Kohm 1/4 watt resistor
*R65 - 10 Kohm 1/4 watt resistor
*R68 - 4.7 Kohm 1/4 watt resistor

And, once again, for a System 11 (nothing) or a System 11A MPU, both of which have onboard amplifiers in the upper left corner and require 12VDC power, be sure to retain or replace the following parts:
*L2 - 4.7uH inductor (or a simple jumper)
*C27 - .001uf/50V ceramic capacitor
*C28 - .001uf/50V ceramic capacitor
*C29 - 100uf/25V electrolytic capacitor
 

====Connecting a logic probe to the MPU Board====
[[File:WMS Sys9 Logic Probe.JPG|300px|thumb|left|Logic Probe connected to System 9 MPU Board]]
[[File:WMS Sys11 Logic Probe.JPG|300px|thumb|right|Logic Probe connected to System 11 (11A) MPU Board]] 

Of course, +5v and ground can always be acquired at any one of the bypass capacitors, which are located at most every chip, and simply labeled as "B".
 

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

[[File:WMS Sys9 comp PSU.JPG|300px|left|thumb|System 9 MPU connected to a PC power supply]]
[[File:WMS Sys11 comp PSU.JPG|300px|right|thumb|System 11 MPU connected to a PC power supply]] 
The 1J17 power connection is essentially the same for System 9 and all variants of the System 11 MPU boards. The ground connection can be attached to pins 1 through 3. The +5vdc connection can be connected to pins 4 through 6. -12vdc gets connected to pin 8 and +12vdc gets connected to pin 9.
 

===Game resets===
System 9/11 games are far more tolerant of low line conditions vs. the newer WPC games. Some things to check if the game is resetting are the usual culprits for this type of thing: connectors, filter capacitors, slam switches, bad chip sockets, etc. It is good preventative maintenance to replace the +5 volt filter capacitor on the power supply with a new one; most of these are 25+ years old and might be getting to the point of wearing out. Certainly replace them if you are getting resetting on your system 11 game. 

Most system 11 games give an indication that they've been slam tilted; if you're getting a "game reset" but you get a noise and/or a message on the displays beforehand, it is probably a slam switch issue vs. a true reset issue. Check all the slam switches in the game (usually the coin door is the main one, and also the ball roll tilt if present). 

===Solenoid problems===

====A/C solenoid/flasher problems====
[[File:System11AuxDriverBoard.jpg|400px|thumb|left|Williams System 11 Auxiliary Power/Driver Board, showing the A/C select relay, the clear "cube" at the top, center of the picture.]] 
The A/C select relay is a dual "make/break" (DPDT, double pole, double throw) relay that supplies power to either the "A-Side" or the "C-Side". It is located on the Auxiliary Power/Driver Board for games that use the board which was introduced with Big Guns and used on all subsequent games. For games prior to Big Guns, like F-14 Tomcat, the relay is probably located under the playfield. There are exceptions. High Speed and Grand Lizard do not use an A/C select relay. Road Kings uses one for a handful of solenoids, but this game did not follow the 1-8 solenoid convention which games after it adopted.

There are a couple ways that the A-Side / C-Side (A/C after this) relay circuit can fail. If the driving transistor (Q8 for Big Guns and later, Q7 for games prior to Big Guns, and located on the MPU board) shorts, the A/C select relay will be constantly energized, resulting in flashers firing when coils should have fired. If the driving transistor never switches the A/C select relay on, coils will fire when flashers should have fired.

Testing this behavior is easy. Use the diagnostic buttons to select solenoid test, and watch carefully to see what fires. The display will show the coil/flasher under test. The first 8 drive circuits tested will have an "A-Side" and a "C-Side". That is, circuits will fire in the following order: 1A, 1C, 2A, 2C, ... 8A, 8C. If the A/C select circuit is not working correctly, the same coil or flasher will fire twice in a row, once for the A side and once for the C side.

The A/C select relay is generally solenoid 12 in coil test. Placing the "Auto Advance" button in the up position, to repeatedly test solenoid 12, should allow you to hear the A/C relay clicking on and off.

If all of "one side" of the A/C select circuit is not working, the fuse supplying the voltage to that side may be blown. F2 (DC side of BR1) and F8 (AC side of BR1) fuse the 25V circuit. F4 (DC side of BR2) and F7 (AC side of BR2) fuse the 50V circuit. Another suspect is fractured solder joints on the A/C select relay. Reflowing these solder joints is simple. The A/C select relay is relatively heavy and it's weight puts stress on the solder connection at the printed circuit board.
 

[[File:System11A-CRelay-OKOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing normal, working switch contacts.]] 
It is rare for the A/C relay itself to fail. A possible source of trouble are the miniature contacts on the relay wipers. These are high power, high current, contacts that can be filed with a small point file to restore proper current carrying capacity. Under no circumstances should you ever use contact cleaner on these contacts, as this could cause a spark or fire to occur. Be careful to not mangle the contact wipers in an attempt to adjust them. Adjust with care. 99% of the time, these switch contacts need no maintenance at all.
 

[[File:System11A-CRelay-WeldedOnBothSides.jpg|300px|thumb|left|Williams System 11 Auxiliary Power/Driver Board A/C Select Relay showing "welded" switch contacts.]] 
Pictured at left is a disassembled A/C select relay with both the A Side and the C Side connected at the center contact pads. It's rare for one of these relays to "weld" itself to both sides. In this particular instance, the game would fire both the A-side coil and the C-side flasher at the same time.
 

Other failure points are the connectors and headers connecting the aux driver board to the main cpu/driver board. Fractured solder joints can affect the proper operation of the relay. It is good practice to replace, or at minimum, reflow the header pins, and to replace connector pins in their housings with new pins. System 11 games use .156 connectors in most locations.

And finally, the solder joints holding the A/C select relay to the board may fracture and cause loss of connectivity.

On a related note, if the flashers never illuminate during game or test, but the A/C relay physically engages, likewise the flasher lamps are good, and power is present at the lamps, suspect potential failure of the U1 (4N25) U1 optocoupler on the interconnect board. Starting with Jokerz, the U1 optocoupler on the D-12313 interconnect board was used to identify whether or not the A/C relay has engaged. Under normal operation, if the A/C relay has engaged, the voltage on the "C" side passes back to the optocoupler. In turn, there is a switch on the switch matrix, typically switch 2, which receives the signal from the U1 optocoupler. Note that U1 is on some previous games like Taxi, but it was not used.

====Special solenoid problems with RottenDog MPU board====
[[File:RottenDogMPUDIPSwitches.jpg‎|300px|thumb|left| RottenDog MPU with a red switch bank for selecting either Williams or Data East special solenoid implementation.]]
[[File:RDMPU004DIPSwitches.jpg ‎‎|300px|thumb|right| These DIP switches on this RottenDog are configured for a Williams game, even though they do not seem to match the PCB silkscreen.]] 
The RottenDog aftermarket MPU board can accommodate both Williams and Data East special solenoid implementations. This is accomplished with an 8 DIP switch bank, pictured at left. If set to the wrong game system, special solenoids will not operate properly in your game. Note: The DIP switch positions should be set the opposite of what you might think, based on the PCB silkscreen.
 

====Special solenoid problems====
[[File:SpecialSolenoidCircuit.jpg|500px|thumb|right|A typical special solenoid circuit]] 
Special solenoids on system 11 games are similar to the earlier variants used on all previous Williams' board sets. During gameplay/test modes the primary switches on the special solenoids (usually the pops and slings) are active, allowing actuation of those switches to fire the solenoids. This is done by grounding an input to a 7402 logic chip which in turn pre-drives a 2n4401 pre-driver transistor which drives a TIP122 Darlington transistor to fire the solenoid.

During solenoid test mode only, the secondary path to the 7402 is utilized instead to fire the solenoids. Since there are 2 paths to fire the solenoids, it is possible for a special solenoid to work in game/test mode, but fail the solenoid test due to a failed PIA or 7402 chip, and vice-versa.

'''Note:''' The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the primary switch associated with the special solenoid device. Therefore, System 9 special solenoids are not activated during solenoid test.

If a special solenoid actuation switch locks on, the solenoid itself will lock on as well, (hopefully) blowing the associated fuse before blowing all or some of the TIP122/2N4401/7402 circuit. An inline fuse holder can be added to all special solenoids with a 1 amp fuse installed to help prevent this situation.

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.

Most system 11B games do not use the special solenoids in the same way. Special solenoid switches were added to the switch matrix instead, keeping all or some of the solenoid pulses under CPU control. It is easy to identify whether a game has CPU controlled special solenoids by inspecting the activation switches on the special solenoids. If there are both a primary and a secondary switch installed, the game operates via the direct-fire special solenoid setup. (Note that a secondary switch in the case of slingshots does not mean the normal 2nd switch all slings shots employ. Rather, it refers to a switch that only activates when the sling activates. It is installed near the pivot point of the sling arm underneath the playfield.) Also the secondary switches go to CPU connector J18. If nothing is connected to J18, then the special solenoids are CPU controlled. In games like BK2K only the kickers are CPU controlled while the pop bumpers still use the secondary switches. There was no rhyme or reason (no definitive start / stop point) which System 11B titles used special solenoid secondary switches, and which did not. Please refer to the game list [http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#System_11B above] to determine which did / did not use the secondary switches.

[[File:WMSSystem11Zener1N5234.jpg|300px|thumb|left|6.2V Zener Diodes (ZR3-ZR8) that "protect" the board logic from shorts between the sense switches and coil power. Note: in this image, ZR7 and ZR8 have been replaced]] 
The usual cause of special solenoid circuit failure is a stuck switch that locks the associated solenoid on, causing the TIP-122 transistor to fail and the coil to get so hot that the winding insulation melts (causing a reduction of coil resistance, eventually approaching zero ohms). The zener diode (pictured, left) in the circuit may fail shorted as well. This will cause the associated coil to lock on even after repair of the other damaged circuitry since the zener is connected directly to ground. The shorted zener diode causes the 7402/2N4401/TIP122 circuit to react identically to a switch closure. Gack!

Note: If your game doesn't use the special solenoid switch inputs as in most System 11B games and all System 11C games (i.e. no connection at 1J18), then these zeners serve no purpose and may be clipped off.
 

====Unusual Solenoid Problems====
[[File:WhirlwindPinchedWire.jpg|300px|thumb|left|A pinched wire (white/brown) that causes a tough to find solenoid problem.]] 
The System 11 method of securing boards sometimes causes odd problems. The securing screws must be removed completely to remove a board vs the improved WPC method of sliding the board off the screw head via a "keyhole".

When securing the boards, it's important to ensure that wires aren't pinched behind the board. If a wire is pinched severely enough, the insulation will be displaced and the conductor will contact the backbox ground plain, which can cause a wide range of odd problems.

The wire in the picture shown at left happened to be the ground path for coil #1, the outhole kicker on Whirlwind. When the game was powered on, the coil would lock on until the blanking circuit became active. Pressing the diagnostic/audit coin door button would also result in the coil locking on. This was actually the A/C relay flipping to the coil side for diagnostics and providing power to the coils. The outhole coil had a path to ground via the pinched wire and would lock on. A game could be started and the coil appeared to work properly until any of the 1 through 8 coils were activated (when the A/C select relay would energize again). At that time, the outhole coil would fire at the same time as the other 1 through 8 coil.

This one was a real head scratcher!
 

===Flash Lamp Problems===
[[File:System11WarmingBoard.jpg|300px|thumb|left|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 wired 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.]]
System 9/11 flash lamps 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: Warming boards are not shown in any of the System 11 documentation.

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.
 

===Lamp problems===
This may seem painfully obvious, but with any lamp problem, where all lamps in the same circuit are not lighting, first see if the associated fuse is blown.
 

====General Illumination Issues====
As a rule of thumb, general illumination (GI) lamp issues with System 9 or 11 games are dependent on the era of the game. The reason for this is GI circuits passed through different boards over the years. And, the majority of GI issues are typically due to the circuit board. Not so much the circuit board itself, but the junction between the header pin connections on the circuit board and the connector pins located in the female housings. 

It is extremely common for the header pins and / or the female connections related to the GI circuit to heat up, and in worse cases char or burn. When some of these games were in operation earning money, they could potentially be turned on for 8, 12, or more hours every day. If the connectors were compromised at some time in the game's life, the issues become compounded. 

The problem is a vicious cycle. If either side of the connector heats up, it creates more resistance. If it creates more resistance, it draws more current. If it draws more current, it heats up. This cycle continues until the connector blows the circuit's fuse (provided the proper fuse is installed and not by-passed), the connectors are so bad that the circuit no longer has continuity, or the connectors are replaced with new ones. It is recommended that both the male header pin connector be replaced and the associated pin connectors which connect to it. Replacing only one side of the connector is only asking for repeat problems down the road. Header pins rated for 7 amp are highly recommended as a replacement. If the 7A headers are used, the likelihood of the connector failing due to heat is greatly reduced. Likewise, the use of Molex Trifurcon connector pins are recommended. 

Another prevalent problem is the failure of the relay board or the relay board connectors. GI relay boards are typically found under the playfield and on the back of the lamp insert panel. The job of the relay board is to switch the GI lamps on/off for special lighting effects. Over many years of operation, the solder joints on the connector may fracture. Although it is more common for the male/female connectors to burn badly. Repinning these connectors, as is typical for GI connectors, is the prescribed fix. 

=====Games From Space Shuttle to Fire!=====
[[File:WMS Sys11 GI Circuits.JPG|300px|thumb|left|Typical System 9/11 Power Supply with GI Drivetrain Notated]] 
During this time period, general illumination entered the power supply [1 / 2], was parsed, and exited the power supply as 4 separate circuits [4]. Although there were 4 discrete GI circuits with 4 separate fuses [5], all 4 circuits were turned on/off via one relay [3] located on the power supply. 

Note that the factory connection on the power supply for System 9 games differs than what is shown in the picture. Connections [1 / 2] do not exist on System 9 games, and only two wires are used to input the general illumination instead of four.
 

=====Games From Big Guns to Swords of Fury=====
[[File:Cyclone Interconnect.JPG|300px|left|thumb|The interconnect board from a Cyclone mounted to the left side of the backbox]] 

With all the games mentioned in this particular section, there were some design growing pains. Williams was creating a preliminary interconnect board, however, it was very different from game to game at first. Therefore, GI issues may occur at the power supply connections, the interconnect board connections, and / or at one of the discrete GI relay boards used. Since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.

A shown at the pic on the left, the general illumination headers, connectors, and connector housings have been changed out due to fatigue / failure. This is a common failure point on games such as Big Guns, Space Station, and Cyclone.
 

=====Games From Taxi to Bugs Bunny's Birthday Ball=====
The games included during this era used a somewhat standardized interconnect board located below the CPU board. The GI circuits coming directly from the transformer enter the board on the right side at connector J6. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. In actuality, the GI wires are only 4 wires, instead of 8 wires. Once the upper 2 wires reach the board, each of them are daisy-chained through the insulation displacement connector (IDC). Equally, the bottom 2 wires are connected in the same fashion. This was presumedly done to reduce cost, and decrease the life expectancy of the connection as a whole. 

[[File:WMS Interconnect BK2K GI Marked.JPG|left|300px|thumb|Williams Interconnect Board with general illumination wire colors marked. Interconnect board is from a Black Knight 2000]]
The most typical header connections that fail on the interconnect board are J6 (the GI input and return) and J7 (the GI output and return lines to the backbox insert). The purpose of the picture to the left is to easily identify what GI circuits pass through what connections. This will aid in attempting to check the continuity of your rework, whether only replacing just one of the header connectors or both. 

Please note that the wiring color codes for J6 in the pic are not the incoming wire colors. The wiring codes in the pic are illustrated this way to determine where the GI circuits disperse throughout the board. The game's schematics in the manual include this information too.
 

Keep in mind that discrete GI relay boards were still used during this time period. Dependent on the game, there may be one to three discrete GI relay boards used. Again, since single-sided circuit boards were used for the GI relay boards, cracked solder joints where the relay is soldered to the board is possible in addition to the header pins.
 

======Repairing the General Illumination Input Connector / Wiring======
[[File:WMS_Sys11_Butterfly_GI.jpg|thumb|300px|left|General Illumination input connector with looped (butterfly) wiring]]
[[File:Sys11 Interconnect GI Connection.jpg|thumb|300px|right|One method for repairing the GI input connector]]
From the factory, only 4 wires total were connected to the GI power and return input connector, which is located on the right hand side of the interconnect board. With only 4 discrete connections per wire from the transformer, 8 wires are needed to connect to the interconnect board. The top 4 wires are yellow and the lower 4 wires are yellow with a white trace. To increase 2 wire connections to 4 wire connections, the wires connect to the IDC connector via one connector pin, pass through that connector pin, and loop back to another connector pin. In doing this, the life expectancy of the connector and the header pins on the interconnect board are reduced (too much current for these connections to maintain over their lifespan). The end result is typically burnt connector pins, housings, headers, and in some cases, the interconnect board too.

To resolve the burnt connection issue, the header pins on the interconnect board should be replaced with new ones. Preferably 7A higher current rated header pins. As for the harness side, the housing should be replaced too, and Molex Trifurcon crimp pins used within the housing. To compensate for the extra wires needed, each of the input wires will need a "Y" junction soldered in place. To do so, take a small piece of wire approximately 4" - 5" long. In the middle of the small piece of wire, carefully strip the insulation, leaving about 1/4" of exposed wire. Place a piece of heatshrink on the single incoming wire. Then, bend the small piece of wire at its center where the insulation is stripped, until both ends leads are nearly parallel with one another. Take the incoming wire, and solder it to the exposed wire in the center. The end result will look like a rudimentary "Y". Pull the heatshrink over the junction, and that's it. This needs to be done for the remaining 3 wires.

In addition to the wire modifications, you can also do a board modification. The J6 connector on the right side can be burned to a crisp. Often lifting pads under the printheader. To repair this you can add a jumper wire to the top 4 traces, connecting pin 1-2-3-4 together. This can also be done for the bottom 2 traces, connecting pin 6-8 together, but you are still missing pins 5 and 7 to be connected to 6 and 8. Turn the board over and solder a jumper over pins 5 thru 8. The same can be done for pins 1 thru 4. Now you have the best possible connection.
 
<center>
<gallery widths=300px>
file:Bally_interconnect_board_Dr_Dude_1.jpg|Dr Dude Interconnect Board with Modification
file:Bally_interconnect_board_Dr_Dude_2.jpg|Dr Dude Interconnect Board modification details (front)
file:Bally_interconnect_board_Dr_Dude_3.jpg|Dr Dude Interconnect Board modification details (back)
</gallery>
</center>
 

====Controlled Lamp Issues====
=====Lamp Columns or Rows from n to 8 Inoperative=====
[[Image:BrokenSIPResistorLampMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing lamp matrix columns 5, 6, 7 and 8 to fail.]]
[[Image:BrokenSIPResistor.jpg ‎|300px|thumb|right|The same broken SIP resistor after removal.]] 
 

=====Lamp Sockets=====
Failed lamp sockets are not very common with System 9-11c games. If a specific lamp will not illuminate, spinning the lamp socket canister or solder tab can resolve the issue in some cases. One thing to keep in mind is that all controlled lamp sockets have a diode soldered to two of the lamp socket tabs. Due to this, the legs of the diode can get pressed against other leads on the lamp socket resulting in an electrical short. The end result may be a lamp which shines more brightly than other lamps in the same column or row, or a whole lamp column or row will illuminate dimly when they shouldn't be lit at all. The resolution is to inspect all associated lamps in the column or row, and look for solder tabs or diode legs touching where they should not be. 

=====Lamp Boards=====
Starting with Pinbot, Williams introduced lamp boards. Lamp boards were used in areas where lamp inserts were positioned too closely together, and it did not make logical sense (or it was not physically possible) to use individual lamp sockets. With subsequent games, lamp boards were used whenever lamp inserts were "nested" in groups. This trend was presumedly done to save on assembly and production costs. One benefit of lamp boards is that bulb replacemnt became easier in most cases. A simple turn of the twist lamp socket (WMS # 24-8767), and the 555 bulb could be removed. 

[[File:WMS Sys1WMS Sys11 Early Lamp Board.jpg|300px|thumb|left|Early direct solder lamp board as seen on Pinbot - the large color matrix below the top and right colored targets]] 
The first generations of lamp boards had the lamp column and row wires soldered directly to the board. On one hand, this is beneficial, because there is one less mechanical connection used in the lamp circuits. On the other hand, it makes it more difficult to remove the lamp boards completely from the game to clean and / or service. On the plus side, very little goes wrong with the direct wired lamp boards.
 

[[File:PCBMountLampDivot.jpg|300px|thumb|left|"Divots" in the connection pad of a "twist in" lamp.]] 
Two things that can fail 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.
 

[[File:WPCPCBLampBoardHeaders.jpg|300px|thumb|left|The solder on these header pins has been reflowed nicely.]] 
With Fire!, 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. This style of lamp board is susceptible to the same issues (bad diodes and divots) as mentioned in the direct wired lamp boards section above.
 

===== Adjacent Columns or Rows Lighting Simultaneously =====
[[Image:WilliamsS11ShortedLampColumnDrives.jpg|300px|thumb|left|Column drive transistor tabs touching, shorted together. Here, lamp columns 3 and 4 would light at the same time.]] 
A problem seen fairly often is the tabs of either column drives or row returns touching, and therefore shorted and causing more than one column (in the picture at left) or row to light at the same time. If you have this issue, it's easy to quickly examine the column drive and row return transistors.
 

===== Lamp Matrix Row and Column Testing =====
The CPU logic for the lamp matrix can be tested by connecting a spare lamp using a jumper wire. The following sections show the separate procedures for testing the lamp matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.
 

'''Testing the lamp matrix columns:'''

[[Image:lamp_matrix_test_sys11a_columns.jpg|600px|thumb|left|Jumper connection for testing lamp matrix columns.]]
 

Use the following procedure to test the TIP42 transistors that drive the lamp matrix columns. Note that a diode is not needed for these tests since it's function is to prevent interaction between the lamps in the matrix. In this test we are only connecting a single lamp at a time.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J6 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J7 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 1J7. There is no pin 5 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>1J7-1</center> || <center>Yel-Brn</center> || <center>1</center> || <center>Q66</center>
|-
|<center>1J7-2</center> || <center>Yel-Red</center> || <center>9</center> || <center>Q64</center>
|-
|<center>1J7-3</center> || <center>Yel-Orn</center> || <center>17</center> || <center>Q62</center>
|-
|<center>1J7-4</center> || <center>Yel-Blk</center> || <center>25</center> || <center>Q60</center>
|-
|<center>1J7-5</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J7-6</center> || <center>Yel-Brn</center> || <center>33</center> || <center>Q58</center>
|-
|<center>1J7-7</center> || <center>Yel-Blu</center> || <center>41</center> || <center>Q56</center>
|-
|<center>1J7-8</center> || <center>Yel-Vio</center> || <center>49</center> || <center>Q54</center>
|-
|<center>1J7-9</center> || <center>Yel-Gry</center> || <center>57</center> || <center>Q52</center>
|}

'''Testing the lamp matrix rows:'''
[[Image:lamp_matrix_test_sys11a_rows.jpg|600px|thumb|left|Jumper connection for testing lamp matrix rows.]]
 

Use the following procedure to test the TIP102/122 transistors that drive the lamp matrix rows.

#Remove the backglass and open the insert to get access to CPU board connectors 1J6 (row) and 1J7 (column).
#Unplug connectors 1J6 and 1J7 (lower right corner of CPU board)
#Turn the game on and go to the "All Lamps" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 2
#Clip one end of the test jumper to 1J7 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J6 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 1J6. There is no pin 4 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>1J6-1</center> || <center>Red-Brn</center> || <center>1</center> || <center>Q80</center>
|-
|<center>1J6-2</center> || <center>Red-Blk</center> || <center>2</center> || <center>Q81</center>
|-
|<center>1J6-3</center> || <center>Red-Orn</center> || <center>3</center> || <center>Q82</center>
|-
|<center>1J6-4</center> || <center>Key Pin</center> || <center> </center> || <center> </center>
|-
|<center>1J6-5</center> || <center>Red-Yel</center> || <center>4</center> || <center>Q83</center>
|-
|<center>1J6-6</center> || <center>Red-Grn</center> || <center>5</center> || <center>Q84</center>
|-
|<center>1J6-7</center> || <center>Red-Blu</center> || <center>6</center> || <center>Q85</center>
|-
|<center>1J6-8</center> || <center>Red-Vio</center> || <center>7</center> || <center>Q86</center>
|-
|<center>1J6-9</center> || <center>Red-Gry</center> || <center>8</center> || <center>Q87</center>
|}

=====Using MOSFETs in the Lamp Matrix Circuitry=====
Procedure by Marco Albus 
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. Using modern MOSFETs (IRF9530, IRF9Z34N or FQP17P06), the heat (and power consumption) can be reduced substantially.

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).

[[File:DEMOSFETSchematic.jpg|200px|left|thumb|Typical "Zero Ohm Jumper" implemenation (left), "Voltage Divider" implementation on right. Image courtesy of Marco Albus.]]
The schematics shown at left compare the widely used "Zero Ohm Jumper" implemenation with the "Voltage Divider" implementation that uses two 1K, 1/4 watt resistors to divide the source 18 VDC in half. Doing so drives the MOSFET with a 9 VDC Vgs. 

======MOSFETs Installed in a System 9 MPU Board======
[[File:WMS Sys9 Lamp Column FET Front.jpg|300px|left|thumb|1K resistors and IRF9Z34N FETs installed on the component side of the board.]]
[[File:WMS Sys9 Lamp Column FET 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 Q23-30
*Remove the 27 Ohm resistors R101, 103, 105, 107, 109, 111, 113, 115
*Remove the 2.2K ohm resistor network SR5
*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.
 

======MOSFETs Installed in a System 11 MPU Board======
[[File:WMS Sys11 Lamp FETs Front.jpg|300px|left|thumb|1K resistors installed on the component side of the board.]]
[[File:WMS Sys11 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 Q52, 54, 56, 58, 60, 62, 64, 66
*Remove the 27 Ohm resistors R82-89
*Remove the 2.2K ohm resistor network SR16
*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:System11_mosfet.jpg|300px|left|thumb|A very clean alternate implementation with resistors on the component side. ''Image courtesy of PinSider DumbAss''.]] 
Shown at left is a very clean installation of all parts on the component side of the board. Note that the 1K resistors are situated such that the "body" of the resistor passes between the MOSFETs instead of the legs, thereby eliminating the possibility of a short.
 

===Switch problems===

====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 Columns or Rows from n to 8 Inoperative====
[[Image:BrokenSIPResistorSwitchMatrixColumn.jpg ‎|300px|thumb|left|A broken SIP resistor, causing switch matrix columns 5, 6, 7 and 8 to fail.]] 
 

====Switch Matrix Row and Column Testing====

The CPU logic for the switch matrix can be tested by simulating switch closures using a jumper wire on both System 9 and System 11 (all revision levels) MPUs.

[[Image:WMSSystem9SwitchMatrixTesting.jpg|300px|thumb|left|Testing the System 9 switch matrix, but jumpering from pins on 1J8 to pins on 1J10.]] 
As seen at left, testing the switch matrix rows and columns on a System 9 MPU is identical to testing on a System 11 MPU except for which connectors to use. The switch columns on the System 9 MPU at 1J8 are numbered right to left. The switch rows at 1J10 are numbered left to right. 1J9 is available (sometimes not stuffed) for opto switch processing, although this feature may never been used.

The System 9 switch matrix operates on 5VDC. The switch columns at 1J8 are "strobed" by being pulled to ground successively by the 6821 PIA. The switch columns are normally pulled high via a pull-up resistor. If the switch at the intersection of the column and row is closed, when the column is strobed, the row will be pulled low too. In this way, the processor knows which column it strobed, and which rows return that strobe.
 

The following sections show the separate procedures for testing the system 11 switch matrix columns and rows. The example is on a Sys11A PinBot, but applies to all Sys11 CPU boards.

'''Testing the switch matrix columns:'''

[[Image:Sys11_switch_matrix_test_col.jpg|600px|thumb|left|Jumper connection for testing switch matrix columns. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J10 pin 9, the leftmost pin on the connector
#Touch the other end of the jumper to 1J8 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated. The test may report the switch name, refer to the switch matrix table in the manual to correlate the name to the switch number.
#Move the jumper to 1J8 pin 2 and check the reported switch by comparing to row 1 in the switch matrix table
#Continue to test the rest of the pins on 1J8. There is no pin 6 as it is the key.

The following table shows the switch number that should be reported for each of the column pins.
{| class="wikitable"
!   Pin   
! Wire Colors 
! Switch number 
|-
|<center>1J8-1</center> || <center>Grn-Brn</center> || <center>1</center>
|-
|<center>1J8-2</center> || <center>Grn-Red</center> || <center>9</center>
|-
|<center>1J8-3</center> || <center>Grn-Orn</center> || <center>17</center>
|-
|<center>1J8-4</center> || <center>Grn-Yel</center> || <center>25</center>
|-
|<center>1J8-5</center> || <center>Grn-Blk</center> || <center>33</center>
|-
|<center>1J8-6</center> || <center>Key Pin</center> || <center></center>
|-
|<center>1J8-7</center> || <center>Grn-Blu</center> || <center>41</center>
|-
|<center>1J8-8</center> || <center>Grn-Vio</center> || <center>49</center>
|-
|<center>1J8-9</center> || <center>Grn-Gry</center> || <center>57</center>
|}

'''Testing the switch matrix rows:'''
[[Image:Sys11_switch_matrix_test_row.jpg|600px|thumb|left|Jumper connection for testing switch matrix rows. This picture shows a diode which is not necessary for this test.]]
 

#Remove the backglass and open the insert to get access to CPU board connectors 1J8 (column) and 1J10 (row).
#Turn the game on and go to the "Switch Edges" test in the Test/Diagnostic Menu. This is done by opening the coin door an pressing: MANUAL-DOWN, ADVANCE, AUTO-UP, ADVANCE x 6
#Unplug connectors 1J8 and 1J10
#Clip one end of the test jumper to 1J8 pin 1, the rightmost pin on the connector
#Touch the other end of the jumper to 1J10 pin 1, the rightmost pin on the connector
#The display should report that switch 1 was actuated
#Move the jumper to 1J10 pin 2 and check the reported switch by comparing to column 1 in the switch matrix table
#Continue to test the rest of the pins on 1J10. There is no pin 4 as it is the key.

The following table shows the switch number that should be reported for each of the row pins.

{| class="wikitable"
!   Pin   
!Wire Colors
!Switch number
|-
|<center>1J10-9</center> || <center>Wht-Brn</center> || <center>1</center>
|-
|<center>1J10-8</center> || <center>Wht-Red</center> || <center>2</center>
|-
|<center>1J10-7</center> || <center>Wht-Orn</center> || <center>3</center>
|-
|<center>1J10-6</center> || <center>Wht-Yel</center> || <center>4</center>
|-
|<center>1J10-5</center> || <center>Wht-Blk</center> || <center>5</center>
|-
|<center>1J10-4</center> || <center>Key Pin</center> || <center> </center>
|-
|<center>1J10-3</center> || <center>Wht-Blu</center> || <center>6</center>
|-
|<center>1J10-2</center> || <center>Wht-Vio</center> || <center>7</center>
|-
|<center>1J10-1</center> || <center>Wht-Gry</center> || <center>8</center>
|}

====Shorted or non-working switch column====

One or more failed switch columns can be caused by a failed column drive transistor (Q42 through Q49, all 2N4401s) or a failed 1K SIP resistor pack at SRC6.

The column drive transistor part was changed with the system 11B MPU. System 9 to 11A MPUs use 2N3904 transistors at location Q42 to Q49 with 1.5Kohm inline resistors (R71 through R78). These column drive transistors fail quite often as these MPUs age. These 2N3904 transistors can be replaced with 2N4401s.

When System 11B was introduced, the switch column drives were changed to 2N5550s with 470 ohm inline resistors. The more commonly found, and beefier 2N5551, is a good substitute for the 2N5550. Before replacing the transistor, be sure which kind the board uses. Some early system 11B MPUs were stuffed with 2N3904s despite the schematics indicating otherwise.

A broken SIP can also cause a switch column not to work. This usually happens with System 11 and 11A CPUs. With 11B WMS also changed the switch section layout and eliminated most of the SIPs. The likely candidates are SRC6 and SR11. In the case of SRC6, measure resistance between pin 1 and 2 to 9. If it's broken it's usually open after pin 3 or 4. This is a bussed 1K SIP with additional 470pfd capacitors connected to ground and practically NLA. Fortunately the caps are not needed because they are also mounted on the board so it can be replaced with a standard 9-8 1K SIP. Pin 10 which is the common ground for the caps is not used here. SR11 is a standard bussed 560 ohm 10-9 SIP. Here you measure resistance between pin 1 and pin 2 to 10. Be aware that two types of SIPs are used on the board: bussed and isolated. If you suspect a different SIP has failed check the schematics for the pin layout.

[[File:WMS-Brokensip.jpg|300px|thumb|left|A broken resistor SIP.]] 
Pictured at left is a broken resistor package similar to SRC6 but out of a System 11 master display. As can be seen, the part may look solid to the naked eye, but it's actually fractured.
 

====Ground Row Shorts====
[[File:WMSSystem11CrackedSR11.jpg|300px|thumb|left|Note the fracture in the SIP at SR11. The fracture became apparent only after desoldering the part.]] 
A possible cause for one or more ground row shorts (indicated by the game software on the score display during switch test) is a fractured resistor SIP at SR11 (a 560 ohm 10-pin bussed resistor network). SR11 is a pull-up resistor that is connected between each switch row return and 5VDC. If the return is not pulled up, that return will look like a low signal continuously, which the MPU interprets as a row ground short. Visual inspection of the SIP might or might not identify the cause of the problem. A better test is to remove the switch row return connector (J10) and probe each pin with a logic probe. The logic probe should indicate "high" for every pin.

Specific to the board pictured at left, a logic probe indicated that J10 pins 1, 2, and 3 were all high but the remaining pins had no signal at all. The fracture can easily be seen between pins 5 and 6 of the SIP (pin 4 isn't used) meaning that pins 6 through 10 were not connected to 5VDC and therefore not pulling the switch row return to logic high. Hence, the MPU declared a row ground short for rows 1 through 5. Note that the actual fracture can rarely be seen prior to attempted removal of the resistor network from the MPU board.
 

==== 4N25 Opto Couplers in the Switch Matrix====

[[File:4N25System11InterconnectBoard.jpg‎|300px|thumb|left|Three 4N25 Opto Couplers on a Williams System 11 Interconnect Board]]
System 11 games that include an Interconnect Board may use 4N25 Opto Couplers to detect power being applied to the flippers or to detect 28VDC being applied to the A/C relay (as in Rollergames). Pre-Fliptronic WPC games that use the -1 power/driver board also use 4N25 Opto Couplers.

These opto couplers are connected to the game switch matrix. Detecting these switches is most often used for lane change and for entering HSTD initials. If one of these functions no longer works, the 4N25 opto couplers should be considered suspect.
 

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.

<center>
<gallery widths=300px heights=300px 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</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>
 

====Opto Switches Not Registering with a Rottendog MPU / Driver Board Installed====
[[File:R-D_11C_Opto_Before.jpg|300px|thumb|left|Older Style Rottendog MPU Board]]
[[File:R-D_11C_Opto_After.jpg|300px|right|thumb|Modified Older Style Rottendog MPU Board]] 
If the opto switches are not registering at all in a game, and a Rottendog MPU board is being used, suspect that it is an older style board. This board can easily be upgraded though. U2 will have to be switched from a 74HCT240 to a 74HC240 chip, and RA5 will have to be changed from a 9-pin 4.7K ohm bussed SIP resistor network to a 9-pin 560 ohm bussed SIP resistor network.
 

===Display problems===
System 9/11 High Voltage Section Repair 
WARNING: This circuit uses high voltages. Don't continue, unless you are confident in your diagnostic abilities.
====High Voltage Issues With the Power Supply====
=====Check Voltages=====
If all displays are blank, your high voltage (HV) section may not be working.
On the Power Supply Board, use a DMM set to DC volts with the - lead grounded, probe the following connector
pins to determine if the HV section needs repair. If the display fuse, F1 is blowing,
you should remove the applicable display connector (with power off) before testing the voltages. Note that these are "loaded" voltages. If you are testing on the bench, or without displays connected, your measurements may vary.
 
If you have Power Supply D-11883 or D-12246: 
3J2 pin 1 = -100 volts DC 
3J2 pin 3 = +100 volts DC 
If you have Power Supply D-8345-xxx: 
3J5 pin 3 = -100 volts DC 
3J5 pin 4 = +100 volts DC 
If the test points are more than about 5 volts out of spec, then your HV section may
be malfunctioning (if you or a previous owner replaced Z2/Z4 with 1N4763A diodes to purposely reduce the display voltage, test readings in the 90's range would be normal). 

Check the table below for a solution.

=====Troubleshooting table=====
{| border=1
| Symptom
| Possible Cause
| Replacement
|-
| 0V ON BOTH +100/-100 lines
| Check F1
| 1/4 Amp SB
|-
| rowspan=5 | 0V on +100V line
| Open Diode D3
| 1N4004
|-
| Open Q2
| 2N5401
|-
| Shorted Zeners ZR1, ZR2
| 1N4730A and 1N4763A
|-
| Open Q1
| MJE340
|-
| Open R1
| 39k ohm, at least 1 watt
|-
| rowspan=5 | 0V on -100V line
| Open Diode D4
| 1N4004
|-
| Open Q4
| 2N5551
|-
| Shorted Zeners ZR3, ZR4
| 1N4730A and 1N4763A
|-
| Open Q3
| MJE350
|-
| Open R4
| 39k ohm, at least 1 watt
|-
| rowspan=4 | F1 1/4 Amp Fuse Blows
| Bad Capacitor at C1 and C3
| 100uF,150V
|-
| Shorted Display
| Display Glass*
|-
| Shorted UDN7180
| UDN7180*
|-
| Shorted UDN6118
| UDN6118*
|-
| +118V on +100V line
| Shorted Q1
| MJE340
|-
| -118V on -100V line
| Shorted Q2
| MJE350
|-
| colspan=3 | * located on display board
|}

 Displays Test With no Shorts Once the displays are tested and shorts are eliminated, we can proceed with the HV section repair.
 Replacing the components in the HV Section Since there are not that many components, if you are having problems isolating the
fault, a quick solution is to replace all the components in
the HV section. If only one side (+ or -) is failing, it is possible to rebuild only the failing side.
Check the parts section of the wiki to find suppliers, and get the replacement parts for one or both failing sides:
 
{| border=1
| align='center' | Part
| align='center' | +Side Part
| align='center' | -Side Part
| align='center' | +,-Location
|-
| Transistor
| MJE340 (or MJE15030)
| MJE350 (or MJE15031)
| Q1,Q3
|-
| Transistor
| 2N5401
| 2N5551
| Q2,Q4
|-
| Zener diode
| 1N4730A
| 1N4730A
| Z1,Z3
|-
| Zener diode
| 1N4763A**
| 1N4763A**
| Z2,Z4
|-
| Resistor
| 39k Ohm,1W
| 39k Ohm,1W
| R1,R4
|-
| Resistor
| 680 Ohm,1/4W
| 680 Ohm,1/4W
| R2,R5
|-
| Resistor
| 330k Ohm,1/2W
| 330k Ohm,1/2W
| R3,R6
|-
| Capacitor
| 0.1uF,250V metal polyester
| 0.1uF,250V metal polyester
| C2,C4
|-
| Capacitor
| 100uF,150V
| 100uF,150V
| C1,C3
|-
| colspan=4 | **This is a 91V Zener to reduce the voltage to prolong display life
|}
[[File:System11PSPartIdentification.jpg|500px|thumb|right|A visual depiction of the parts in a System 11 high voltage section. Note that the legs of the MJE15030/MJE51031 are crossed as this power supply originally used OEM parts SDS-201 and SDS-202]]
Remove and replace HV components<ul><li>Clip the old components from the board (make sure you have new ones first).
<li>Use one of the desoldering methods to remove solder from the holes.
<li>Stuff board with new components.
<li>Check for correct orientation on transistors, diodes and the large capacitor if you replace it.
<li>Leave a little space under components for air flow.
<li>Bend leads on components so they won't fall out when board is inverted for soldering.
<li>Double check that all the correct parts are in the correct places and properly oriented.
<li>Solder the parts to the board
<li>Clip excess off leads
</ul>
 

=====Note on installation of MJE340/MJE350 replacement transistors=====
The MJE340/MJE350 is the heat-sinked transistor. On most Williams boards, this transistor pin configuration is not the same as the original part. It will need to be installed vertically with heat sink attached to the transistor only. The transistor will sit at about a 45 degree angle so the legs can be lined up to fit in the correct holes.

Check your board and insure correct orientation before soldering in place. Late versions of the System 11 series boards were designed to use the pin configuration of the MJE340/MJE350 transistors.

Do not mount vertically if the power supply is designed to use the pin configurations of the newer transistors!

[[Image:MJEInstall.png]]

=====Note on installation of MJE15030/MJE15031 replacement transistors=====
[[File:WMSSys11MJELegsCrossed.jpg|300px|left|thumb|High Voltage section with MJE15031 installed. Note the crossed legs on the left transistor.]]
[[File:WMS Sys11 PS Alt HV Transistor Pads.JPG|right|thumb|300px|Power supply with pads for both styles of HV transistors]]
The MJE15030/MJE15031 are rated for higher power and can be used instead of the MJE340/MJE350 (the MJE340/MJE350 are well within design specifications and are suitable replacements at 1/3 the cost of the MJE15030/MJE15031).

The MJE15030/MJE15031 pin configuration has the Base and Emitter reversed as compared to the MJE340/MJE350. In the image at left, the left transistor (MJE15031) shows one method of crossing the legs safely. The transistor's two left legs are shifted right on position. The third leg is then jumpered to the boards left through hole position. If you prefer not to cross legs, this transistor can also be mounted vertically, but this transistor would be facing the opposite direction as compared to the MJE340/MJE350 pictured above. 

There are some power supplies which have pads for both the SDS-201/SDS-202 or the MJE15030/MJE15031 style of transistors. In the pic to the right, the MJE15030/MJE15031 transistors are installed from the factory, but there are solder pads just below for installation of the SDS-201/SDS-202 transistors. If installing ME15030/MJE15031, the upper pads are used, and no leg crossing is required.
 

Ready to test 
To test the rebuilt power supply, return to the "Check Voltages" section of this guide. 
 
'''Other Resources''' 
The System 9-11 HV section of the PSU is very similar in design to the earlier System 3-7. So it will be worth reading through the [[Williams_System_3_-_7#Power_Supply_Issues|Sys 3-7 PSU Problems]] section entitled '''+/-100v Display HV Section of PSU''', for more detail. It also provides links to source complete HV rebuild kits which will normally cost under $10 shipped.

====Display Panel Problems====
=====Segment Identification=====
[[File:SegmentLetters.jpg|300px|left|thumb|Alphanumeric and Numeric Segment Identification.]]
 

=====Display Will Not Light=====
[[File:PlasmaBallTest.jpg|300px|left|thumb|Testing a high voltage plasma display with an inexpensive plasma ball]] 
If power to the display is correct, and the display was moved to a known working display panel position (if possible), it is possible that the display has outgassed. A plasma ball can be used to determine if a display glass is outgassed. 
[[File:YT.png]] A Youtube video demonstrating the use of an inexpensive plasma ball for this purpose can be found [https://youtube.com/shorts/GGftl3S_OWg?si=T5Cdzyovtar6_Han here]. 

=====Segments Light "In Sympathy" With Other Segments=====
[[File:ShortedSegments.jpg|300px|left|thumb|In this image, segment "b" and segment "k" light simultaneously, even though only one segment should be lit. The last two characters illustrate the issue clearly. Image courtesy of PinSider Pinball50.]] 
Internal shorts within a display glass can cause segments to light "in sympathy" with other segments. That is, segment "b" and segment "k", for example, will both light, when only one of the segments should be lit. Segment "b" will light whenever segment "k" is lit and segment "k" will light whenever segment "b" is lit. This is caused by an internal short within the glass. The short can be confirmed by removing the leads of the associated segments from the PCB and measuring resistance between them. The resistance should be infinite, or open.

In this case, there is no way to repair the glass and it should be replaced.
 

=====Commas stuck on (Players 1&2 or 3&4)=====
System 9: Check IC36 on the MPU (6821 PIA)

Pin 16 = Players 1 & 2
Pin 17 = Players 3 & 4

With the game in attract mode, check these pins with a logic probe. They should go low each time the displays turn off. if they stay high, the PIA is likely bad and will need to be replaced.

=====Display Fuse F1 Blows=====
Testing the UDN Chips 
If the display fuse is blowing, you should check the display board for shorts before connecting
a new or rebuilt power supply to the display board, as a shorted display or chip can damage a good power
supply. Remove the display board from the system. The display characters are driven by the two types
of UDN chips, the UDN7180 & UDN6118 (or UDN6184). Locate these chips (there are several)
on the board and test them with your DMM set to diode check. Clip your + (RED)
lead to the ground trace of the board. Probe the UDN chips as shown in the diagram.
If any shorts are read in the tested pins, the display should not be connected to the power
supply until the shorts are corrected.
[[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 pins labeled 'dont care'), 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.

=====Replacing Display Glass=====
[[File:WMS 7Digit glass change1.JPG|300px|left|thumb|Replacement glass installed with glass nipple in proper location]]
[[File:WMS 7Digit glass change2.JPG|300px|right|thumb|Replacement glass installed after circuit board was drilled to allow for glass nipple in different location]]
All plasma displays have a finite life expectancy. Display glass replacements were and are offered in several configurations. The differences in these configurations are mainly the placement or lack of a display "nipple" on the back of the glass. The glass nipple is what can pose as somewhat of a problem, when replacing a display glass. Williams did place a rather large hole in the display circuit board. However, the placement of the glass nipple has changed. To overcome this issue, a hole can carefully be drilled through the circuit board to allow for the glass nipple. When drilling, drill successive holes, starting with a small drill bit first, rather than drilling one large hole. This will reduce the chances of the circuit board "splintering". 

At one time, [http://www.pinballpcb.com/Displays.html pinballpcb.com] did offer replacement displays and / or just the replacement display circuit boards. Neither of these products are available anymore.

[[File:WMS 7Digit Repair.JPG|300px|left|thumb|Replacement glass installed]] 
Original display glass was secured to its circuit board with double-sided, high tack, foam tape. If this cannot be acquired, a simple method to secure an existing or new display glass is to use silicone caulk or RTV caulk. However, in following this method, the glass must be supported on the board until the caulk cures. Wrapping the glass with rubber bands is a great way to do this. Once the caulk is cured, just cut off the rubber bands.
 

====Logic States of Display Output Signals for a Working MPU Board====
These logic states were recorded from a System 11A board. This board was running Swords of Fury code in display test mode manually paused with all characters / digits on "8". This is for games with a 4 x 7 display board.

L=LOW, H=HIGH, P=PULSE

{| class="wikitable"
!IJ3 (pin)
!Logic State
|-
| 1 || L
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || None (Key)
|-
| 7 || P
|-
| 8 || P
|-
| 9 || P
|-
| 10 || L
|-
| 11 || L
|-
| 12 || H
|}

{| class="wikitable"
!IJ2 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || None (Key)
|-
| 8 || P
|-
| 9 || P
|}

{| class="wikitable"
!IJ1 (pin)
!Logic State
|-
| 1 || P
|-
| 2 || P
|-
| 3 || P
|-
| 4 || P
|-
| 5 || P
|-
| 6 || P
|-
| 7 || P
|-
| 8 || None (Key)
|-
| 9 || P
|}

{| class="wikitable"
!IJ22 (pin)
!Logic State
!IJ22 (pin)
!Logic State
|-
| 2 || L || 1 || L
|-
| 4 || L || 3 || L
|-
| 6 || L || 5 || L
|-
| 8 || L || 7 || L
|-
| 10 || L || 9 || L
|-
| 12 || L || 11 || L
|-
| 14 || L || 13 || P
|-
| 16 || L || 15 || L
|-
| 18 || L || 17 || L
|-
| 20 || P || 19 || P
|-
| 22 || P || 21 || P
|-
| 24 || P || 23 || P
|-
| 26 || P || 25 || L
|-
|}
 

===Sound problems===
====System 9 Sound Problems====

=====Jumper Settings for a newer System 9 Speech Board=====
[[File:WMS Sys9 Speech Board jumpers.JPG|300px|left|thumb|Jumpers Circled on a Comet System 9 Speech Board]] 
As mentioned above, the System 9 speech board is essentially the same as the System 6/7 speech board. However, the newer speech board has jumpers added to increase the flexibility of EPROMs used. Either 2532 or 2732 EPROMs can be used. If using 2532 EPROMs, install jumpers W2 and W4, and remove jumpers W1 and W3. If using 2732 EPROMs, install jumpers W1 and W3, and remove jumpers W2 and W4.
 

=====Missing Sound or Speech Calls=====
To start a sound test, simply press the SW2 momentary switch at the bottom of the CPU board located between connections 1J16 and 1J17. Once SW2 is pressed, the CPU will cycle through all of the sound / speech calls continuously. Each System 9 game has a chart located in the manual, which lists the speech and sound calls made during test. The benefit of the chart in the manual is that it lists the ROM where a particular call originates. If a particular sound / speech call is not heard, the associated ROM listed for that call may be bad. 

Another result of speech calls missing is possibly a bad U2 or U3 on the speech board. Both of these chips are 1458 op-amps.
 

=====Isolating the CPU Sound from the Speech Board=====
Some of the sound / speech calls originate from the CPU board, while the remaining calls originate from the speech board. If after running a game through sound test by pressing SW2, and some sounds are missing or very low in volume, a good idea is to isolate the CPU board from the speech board. All of the sounds originated on the CPU board, leave the board via the 40 pin ribbon cable, and go to the speech board for mixing. Once mixed, all of the sounds and speech are then returned to the CPU board, amplified, and sent out to the speakers. 

Much like the System 6/7 sound and speech boards, the sound can be isolated from the speech board for testing purposes. The System 6/7 Type 2 sound board uses a jumper at position W1. When jumper W1 is installed, the sound board can be diagnosed without the speech board installed. The equivalent with the System 9 CPU board is jumper W10. This jumper is typically not connected. However, when it is connected, the sounds originating from the CPU board can be heard. 

Locate jumper W10 on the CPU board. W10 is located to the right of SW2 on the board. There should be two very small wires clipped on either side of W10, as if W10 was installed and removed. Connect an alligator test lead across the short leads of W10. If the short leads are not present, a short light gauge wire or wire wrap can be tack soldered to the solder pads of W10, or use a jumper wire to connect the lower legs of C32 and R76 which are just right of W10 (see pic, below). With a jumper installed at W10, some sounds should be heard when SW2 is pressed. Sound test, via the coin door diagnostic button is likely to provide sounds for all but sound 7, which is a voice call. If no sounds are heard, further troubleshooting must be performed. 

<center>
<gallery widths=350px heights=350px perrow=3 caption="Adding W10 to a System 9 CPU Board">
File:WMS Sys9 W10 Jumper.JPG|<center>Locating jumper W10</center>
File:WMS Sys9 W10 Jumped.JPG|<center>Temporarily jumpering W10</center>
File:System9JumperTemporary.jpg|<center>Alternate for jumper W10</center>
</gallery>
</center>
 

====System 11 Sound Problems====
System 11 games are known to "hum" a bit. The "hum" is caused by electromagnetic interference from the lamp matrix insinuating itself on the sound circuit. To minimize the interference, ensure all boards are screwed tightly to the backbox ground plain, with all screws installed. This improves grounding and will help minimize "hum". 

Another cause of hum could be an inconsistent +5DC volts from the power supply. An indicator of this being the cause of hum would be the game occasionally resetting as well. Replacing caps C8 and C10 on the power supply may correct this issue. 

Depending on the version of System 11 board, an 11C board or anything else (nothing, 11A, and 11B), sounds and music are handled with different specifics. With the first 3 generations of MPU boards, the sounds originate from the MPU board and the background music originates from the sound board. With the 11C board, both sounds and music are on the sound board, as the MPU no longer has a sound section populated on it. 

=====Volume POT value=====
Some System 11 games shipped with a 5K linear volume POT. Others shipped with a 10K linear volume POT. Both POT values work fine and either can be used to replace a failed volume POT.

Some System 11 games shipped with a 50 ohm resistor soldered to the volume POT. It is thought that this resistor was included so that the volume could never be turned to zero. For route games, at least some sound was thought to increase game earning potential. This resistor can be removed or jumpered around to enable turning the sound volume completely off.

=====Boot Up Diagnostic Tones for the D-11297, D-11298, and D-11581 Sound Boards=====
The D-11297, D-11298, and the D-11581 sound boards all provide diagnostic tones ("bongs") at power on. A single "bong" means that the sound board is operating properly.

Lack of a bong indicates a problem with the sound board or it's connections. The possible causes for failure are numerous, including a failed amplifier, missing or incorrect connector placement, missing or noisy (AC ripple) power for a required voltage (-12VDC), failed speakers or the connection to the speakers, etc.

If the sound board is healthy enough to perform it's own self-diagnosis, it will attempt to indicate the problem by playing a specific number of bongs, as shown in the tables below.

D-11297 & D-11298 Sound Boards
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U3 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem

|}

D-11581 Sound Board
{| class="wikitable"
!"Bong" Count
!Description
|-
|<center>1</center> ||  Normal sound board boot with no problems detected.
|-
|<center>2</center> ||  U5 RAM Problem
|-
|<center>3</center> ||  U4 Sound ROM Problem
|-
|<center>4</center> ||  U19 Sound ROM Problem
|-
|<center>5</center> ||  U20 Sound ROM Problem
|} 

=====Sound Diagnostics Via the MPU Board for Games Prior to 11C=====

Pressing the upper switch of the two switches on the side of the MPU board will test both the CVSD and DAC on the MPU board. The first sound is typically sound ROM (on the MPU) specific, and it is a test of the CVSD chip. The second sound is described as a "twing", and it is a test for the DAC. If no sounds are heard, refer to the potential issues listed above in the previous section. If one "ring" is heard, it denotes that the U23 RAM chip has failed. Two or four rings denotes that there is a problem associated with U21 ROM. Three or five rings denotes that there is a problem associated with U22 ROM.

 

=====Connecting the Speaker and Volume Connections for a System 11 MPU Board on the Bench=====
[[FILE:WMS Sys11 Speaker Volume Connection.JPG|300px|left|thumb|Speaker and Non-adjustable Volume Control Connected on a System 11 MPU Board]] 
To test the sound on a System 11 MPU on the bench, a speaker and volume control must be connected to connectors 1J15 and 1J16 respectively.

The speaker should connect to pins 2 and 3 of 1J15.

In the adjacent pic, a 470Kohm resistor was used in lieu of a volume pot. Other resistor values can be used, but 470Kohm allows the sound to be set to a comfortable audible level. Alligator clips can be used, but if the intentions are to test sound boards in the future, a resistor can be crimped into a .156" housing as shown. This resistor/connector set up can be used on all Williams sound boards from System 3 through System 11.

If using alligator clip leads to power the board, use special care as to not send +12v down the -12v line (the pins are adjacent to one another). Sending +12v down the -12v bus will most definitely destroy the 1408 DAC chip (if populated).
 

=====Sound Is Very Faint Even at Maximum Volume =====
[[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, 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 it is not, then the CVSD has failed.
 

=====Some Sounds Lower Volume Than Others =====
[[Image:System11DACChannel.jpg|300px|thumb|left|The sound section of a System 11 MPU and the 2N3904 amplifying transistor.]] 
Another sound anomaly manifests as some sounds being more faint than others is a failure in the 1408 DAC sound lane channel. In High Speed, for example, "Sound Test" exercises both the 1408 and 55536 sound lanes. Sounds 1, 3, and 5 are all made via the 1408 DAC lane. If those sounds are faint, the issue could be the 10uf capacitor (C8), the 2N3904 transistor (Q1) that is used as a pre-amplifier, the 3.3K resistor (R7), or the 1408 DAC. Eliminating the easy possibilities first, replace the 10uf capacitor. If that doesn't fix the issue, replace the 2N3904. The 2N3904 may "diode test" as failed, but not always. If the issue still remains, replace R7. Lastly, replace the 1408 DAC (U2). An equivalent part that may be used is the DAC0808.

A video, showing the problem and resolution can be viewed [https://www.youtube.com/watch?v=G7fk3PtwvtE here].
 

[[FILE:WMS_Sys11_1408_flipped_lid.jpg|300px|thumb|left|The 1408 in the sound section of a System 11 MPU lost its top!]] 
In another instance, Pin*Bot, all of the sounds were faint, except the last two in test. This ended up being a bad 1408 DAC. The last two sounds were unaffected, because the 55516 CVSD chip handled them. With a visual inspection, the 1408 in the pic could not be determined it was bad, until it was in the midst of being desoldered from the circuit board.

 

===== Voice callouts are much softer than music/sound =====
The sound mixing section on the System 11A and 11B MPU boards were populated with different resistor and capacitor value parts. If an 11A MPU is installed into an 11B game (F-14 into an Earthshaker for instance), it is possible that the voice callouts will be noticeably softer than the other music/sound. The following table details the difference between the two sound mixing sections ''(Thanks to Pinsider "Mneubey")''.

[[Image:System11_11n_sound.jpg|500px|thumb|left|System 11 (nothing) sound section. ''Image courtesy of PinSider "DumbAss"'']] 
  Resistors

    R21 is 12K in 11B, 15K in 11A 
    R22 is 22K in 11B, 27K in 11A 
    R19 is 56K in 11B, 27K in 11A 
    R16 is 180K in 11B, 56K in 11A 
    R17 is 270K in 11B, 220K in 11A 
    R15 is 180K in 11B, 43K in 11A 
    R20 is 12K in 11B, 27K in 11A 

  Capacitors

    C12 is 470pf in 11B, 1200pf in 11A 
    C11 is 100pf in 11B, 180pf in 11A 
    C10 is 470pf in 11B, 1800pf in 11A 

[[Image:System11_11b_sound.jpg|500px|thumb|left|System 11B sound section. ''Image courtesy of PinSider "DumbAss"'']]
 

===== Sound Board D-11581 Mixer Section Resistor Values =====
[[Image:D11581ResistorValues.jpg|500px|thumb|left|"Mixer" section resistor values across D-11581 sound board games. ''Data courtesy of PinSider "DumbAss"'']] 
The sound mixing section on the System 11A through 11C sound boards were populated with different resistor values. The table shown at left details the differences between the sound mixing sections for each game.

Note that the value of R13 will change also. It should be 4.99K for "Fire!" through "Police Force", and 10K for all other games.
 

=====Missing Some Music or Garbled Music with a D-11581 Sound Board and 5 Bongs=====
A sound board booting with 5 bongs indicates a failure of the U20 ROM. While U20 could, in fact, have failed, 5 bongs could also mean that the software can't access U20. In one such case where 5 bongs were heard, during music test, tests 4 and 6 would play music but the music was garbled and/or incorrect. The root cause was W10/W11 jumper settings on the sound board that didn't match the ROM size. W10/W11 should be set to the left for 27256 ROMs; to the right for 27512 ROMs.
 

=====Modifying a pre-System 11C Sound Board to use 27512 ROMs (D-11581)=====

[[Image:System11BSoundBoardW2W3.jpg‎|300px|thumb|left|D-11581 sound board jumpers W2 and W3. Note that W3 is "always IN". The solder mask over the W3 jumper trace has been removed for clarity. Normally the trace is covered by a dashed white silkscreen line.]]
[[Image:System11BSoundBoardW2W3Modified.jpg‎|300px|thumb|right|D-11581 sound board jumpers W2 and W3. W3 has been cut to enable use of 27512 ROMs.]]

Some revisions of the D-11581 sound board will not accept 27512 sound ROMs without modification. By the time that revision C was manufactured, jumpers W10 and W11 were added above U20 to enable use of larger ROMs. Prior to that, jumpers W2 and W3 were implemented, but were of little use since both jumpers tied A15 (pin 1) of each EPROM to +5VDC. Making the modification pictured at right, then installing jumper W2, enables the use of 27512 ROMs.
 

=====Jokerz specific sound issue=====
A special case of interference is present on the Jokerz game, which uses a unique stereo sound board. A deficiency in its design prevents all of the noise from being eliminated from the board. Details can be found in the original Williams service bulletin here: [http://www.ipdb.org/files/1308/Williams_1988_Jokerz_William_Service_Tip_For_Audio_Hum.pdf Jokerz service bulletin at IPDB.org]

=====Whirlwind Doesn't play Sound 7 During Test=====
This particularly annoying issue appears to have no impact during gameplay. The only manifestation is that "Sound Test", sound 7 doesn't play. The normal sound is an explosion.

This issue is caused by old game ROM versions at U26 and U27. Revision PA1 doesn't send the command to the sound subsystem to play sound 7, even though sound 7 is displayed on the alphanumeric display. Updating U26/U27 to "LA3" as can be found at www.ipdb.org will correct this issue.

[[file:YT.png]] Correct Whirlwind sounds are demonstrated in a YouTube video found [https://www.youtube.com/watch?v=fy_GXp3Bfzg here].
 

=====Sound Board Theory of Operation (D-11581)=====

[[Image:System11CSoundBoard.jpg|500px|thumb|right|D-11581 Sound Board, Completely Populated and including jumpers W10 and W11]] 

Major components of the D-11581 sound board are:

*68B09E externally clocked CPU, which is also used in all WPC MPU and pre-DCS sound boards
*68B21 Peripheral Interface Adapter, capable of running at 2Mhz
*Up to 3 ROMs. All boards can accommodate 27256 ROMs. Some later boards can be jumpered to accommodate 27512 ROMs.
*6116 RAM (2K bytes). Some later boards can be jumpered to accommodate a 6264 RAM (8K bytes)
*YM2151 sound synthesizer paired with the YM3012 DAC (outputs channel 1 and channel 2)
*55516 CVSD (continuously variable slope delta) audio encoder, which provides a 3rd audio channel
*1408 DAC (digital to analog converter), which provides a 4th audio channel
*Various 74XX ICs that perform address decoding and chip selection logic
*1458 pre-amplifiers and TDA2002 amplifiers

The D-11581 sound board shares a lot of board design and architecture of the pre-DCS sound board that was introduced with WPC games.

Power

Power requirements for the board are supplied via connector J3. The typical sound board power levels are required, 5VDC, 12VDC, -12VDC, and Ground. Three 100uf capacitors reduce noise on the power busses along with several small ceramic caps which filter high frequency noise.

Reset

The on board 68B09E is reset via the external reset signal provided by the MPU board, via connection J4, pin 18. If attempting to operate the board without the MPU board connected, the processor must be manually reset via momentarily grounding pin 37 of the 68B09E.

Clocking

The clocking signal for the board originates at the 8Mhz crystal oscillator. U16, a 74LS74 Dual D-Type FlipFlop divides the clock signal yielding both the "E" and "Q"clock signal. E and Q are phase shifted by one half clock cycle.

Chip Select Logic

Chip select is accomplished via the normal "memory mapped I/O" method, using U14 (74LS139) and U15 (74LS138).
*Chip select for all three ROMs (U4, U19, U20) is implemented by U14.
*Chip select for the RAM (U5), YM2151 (U3), and the 6821 (U12) is implemented by U15.

How sounds are produced

Sound select signals are provided via J4, a dual row .100 connector of 20 pins. These sound selects are held "normally high" via a 4.7K/470pf 10-pin bussed SIP pull-up resistor/capacitor (SR1) tied to 5VDC. These SIP resistor/capacitor parts are no longer available. A bussed 4.7K 9-pin resistor network can be used as a replacement. The capacitor feature of the original part filtered high frequency noise from the communication lines. In practice, noise doesn't impact the interface significantly enough to be of concern.

The MPU board will pull the appropriate sound select signals to ground via the 6821 PIA at Uxx. When the appropriate signals are pulled to ground, the PIA is programmed to interrupt the 68B09E processor via the FIRQ and NMI signals. The 68B09E then reads the sound select signals presented at the 6821s input port (PB0 through PB7) via the processor data bus (D0 through D7).

The processor then employs the 4 sound channels available to it, along with encoded sound files contained in the ROM images, to create the intended sounds.

====Where Do The Sounds Come From?====

The following sections can be used to ensure that all sounds are played by the Williams combined MPU and Sound Board System.

=====System 9 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Comet|| [[file:YT.png]] [https://youtu.be/-2m7vKCeg2A Audio]
|-
| Sorcerer || [[file:YT.png]] [https://youtu.be/pXacwGqv5C4 Audio]
|-
| Space Shuttle || [[file:YT.png]] [https://youtu.be/B-gsuEw1jgU Audio]
|}

=====System 11 Games (alphabetical)=====
{| class="wikitable"
! style="text-align:left;" | Game
! style="text-align:left;" | Audio Demo Link
|-
| Bad Cats || [[file:YT.png]] [https://youtu.be/-JJKPvMBplg Audio]
|-
| Bally Game Show || [[file:YT.png]] [https://youtu.be/vwA4FST62ug Audio]
|-
| Banzai Run || [[file:YT.png]] [https://youtu.be/6D87Z2iUsv0?si=x8BKbDsxHFI_yodb Audio]
|-
| Black Knight 2000 || [[file:YT.png]] [https://youtu.be/uyJlxc2ewtY Audio]
|-
| Cyclone || [[file:YT.png]] [https://youtu.be/pEdSxFu1Zio Audio]
|-
| Diner || [[file:YT.png]] [https://youtu.be/rwCLpG5jU2I Audio]
|-
| Earthshaker || [[file:YT.png]] [https://www.youtube.com/watch?v=eH0FVvbBQUQ Audio]
|-
| Elvira & the Party Monsters || [[file:YT.png]] [https://youtu.be/OS_SRCNaMwg?si=6Wop4YLK2wa6Mco4 Audio]
|-
| F-14 Tomcat || [[file:YT.png]] [https://youtu.be/rG26I-oDK6E Audio]
|-
| Fire! || [[file:YT.png]] [https://youtu.be/dXKRw1GqUcQ Audio]
|-
| High Speed || [[file:YT.png]] [https://youtu.be/yAmJzD9EAZA Audio]
|-
| PinBot || [[file:YT.png]] [https://youtu.be/CoVvhwggLfU Audio]
|-
| Police Force || [[file:YT.png]] [https://youtu.be/Em63v0-zJKk?si=gt3qD2jLsqJFdwlW Audio]
|-
| Pool Sharks || [[file:YT.png]] [https://youtu.be/gceZEgLMaDQ Audio]
|-
| Rollergames || [[file:YT.png]] [https://youtu.be/tN-Ns9eh8Pg Audio]
|-
| Space Station || [[file:YT.png]] [https://youtu.be/9XERXpVGCsY?si=jSNjikeN1nM6GeQy Audio]
|-
| Swords of Fury || [[file:YT.png]] [https://youtu.be/u6baQrse5LI?si=3Y85cpAXqDF5_Qis Audio]
|-
| Taxi || [[file:YT.png]] [https://youtu.be/P7DIs5djK-E Audio]
|-
| Whirlwind|| [[file:YT.png]] [https://www.youtube.com/watch?v=fy_GXp3Bfzg Audio]
|}
 

===Flipper problems===

==== Flipper Circuit Schematics Error ====
[[File:WMS Serial Flipper Schems.JPG|left|300px|thumb|Correct wiring schematic for serial wound flipper coils]]
[[File:WMS Serial Flipper Schems Incorrect.JPG|right|300px|thumb|Incorrect wiring schematic for serial wound flipper coils]] 
Early System 11 and 11A games used serial wound coils. These coils only have a single diode on them. Some of the early System 11 manuals show incorrect wiring for the EOS switch. One of the EOS switch wires should be soldered to the center lug of the coil. However, the other wire should be soldered to the lug with the non-banded side (anode) of the diode, not the lug with the banded side (cathode) of the diode. Manuals which have this misinformation are High Speed, Grand Lizard, and Road Kings. Millionaire and Pinbot appear to be fine.
 

==== Flipper Electrical Problems ====

System 11 (nothing) and System 11A games derive 50VDC flipper power from the "50V Flipper Power Board".
System 11B and 11C games derive 50VDC flipper power from the "Aux Power Supply" board that was introduced with these games.

System 9 and 11 flipper circuitry is identical to all prior Williams System 3-7 games. The design had not changed from even the old electro-mechanical flipper implementation when the End of Stroke switch was introduced.

Yes, Williams used serial wound coils from High Speed to Millionaire and then converted to parallel wound coils beginning with F-14 TomCat and throughout the rest of the System 11 run and into the WPC run. But the basic operation of System 9/11 coils remained "EM-like" whether serial or parallel wound.

There are only three switches that can affect the electrical operation of a System 11 flipper, including strength.

#Switches inside the Flipper Enable relay (K1), located on the MPU board.
#The cabinet flipper button switches.
#An End-of-Stroke (EOS) switch associated with each flipper coil and integrated into the flipper mechanism assembly.

====Series Wound Flipper Coil Operation====
When the flipper enable relay (K1) switches close, a path to ground is provided for the flipper coil. The EOS switch is closed, creating a short across the low power windngs, that removes resistance of the low power windings from the circuit. Only the smaller number of high power windings are "in circuit" with the EOS switch closed.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at the low resistance high power windings of the coil. The coil plunger is pulled into the coil and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, removing the short across the low power windings, and placing them in series along with the high power windings. Together, the total resistance of the coil becomes the sum of both the low power and the high power windings. With more windings, the coil will have higher resistance and hence, lower power. The combined high resistance windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.

====Parallel Wound Flipper Coil Operation====
[[File:ParallelWoundFlipperDiagram.jpg|left|400px|thumb|Parallel Wound Flipper Coil Operation. Diagram courtesy of Chris Hibler.]]
When the flipper enable relay (K1) switches close, a path to ground is provided for the low power windings of the flipper coil. And, since the EOS switch is closed, the high power windings also have a path to ground.

When the flipper cabinet switch is closed by pressing the flipper button, this is the final switch in the path to ground for the waiting power at both of the coil parallel windings. Since electrical current "takes the path of least resistance" the lower resistance high power winding takes most of the current and the flipper "flips". Near the end of the flipper's mechanical stroke, a pawl (a tab that sticks up) on the flipper crank mechanism will open the EOS switch, breaking the path to ground for the high power windings. The high resistance low power windings remain in circuit, and provide "hold" power to the flipper coil. The high resistance low power windings act like a "hold" or "coin door lockout" relay coil, able to withstand being energized for extended periods of time. Without the mechanization of the EOS switch, the high power windings would overheat quickly and damage the coil. For this reason, EOS switch adjustment, and a clean EOS switch, are critical.
 

==== Flipper Mechanical Problems ====

*Return springs
*Fractured nylon bushing
*Insufficient gap between nylon bushing and crank
*Heat damaged coil
*Damaged coil sleeve
*Damaged coil stop
*Flipper shaft slipping within crank
*Others?

===Pop bumper problems===

==Repair Logs and Game Specific Problems and Fixes==
Did you do a repair? Log it here as a possible solution for others.

===System 11 Display Single AlphaNumeric Character Won't Light===
[[File:Sys11B Bridged Header.jpg|300px|left|thumb|A solder bridge on the "digit strobe" connector.]] 
In the category of "things that will make you crazy", the solder bridge pictured at left shorted pins 8 and 9 on the connector that carries the digit strobes to a System 11 display. This prevented one of the digits on the display from ever lighting. It's always a good idea to examine prior work closely. Assuming the prior tech knew what they were doing is not always valid. 

===Using a System 6/7 Speech Board in a Comet===
[[File:WMS Sys9 CPU with 2732 Speech.JPG|300px|left|thumb|A Modified System 6/7 Speech Board Functioning with a System 9 CPU]] 
Should the need arise, a System 6/7 speech board can be [http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Modifying_the_System_6.2F7_Speech_Board_to_Use_2732_EPROMs modified to use 2732 EPROMs] for a Comet.
 

===Using a Data East MPU Board in a System 11 Game===
Whaaaat?!?! Yes, a Data East MPU can be used in a Williams or Bally System 11 game. However, this is limited to System 11C games only, and only a DE 520-5003-03 (Version 3) MPU can be used. The reason for this limitation is because games previous to 11C have some or all of the sound section circuitry on the MPU board populated, the 11C does not. Likewise, DE boards do not have any sound section circuitry located on them by design. The board swap is not a simple drop in replacement though. Some minor modifications have to be performed for the DE board to function properly in an 11C game.

The first hurdle is to properly power the DE board. Connection 1J17 is where power originates on the 11C board. The complimentary connection on a DE board is CN17. The problem is that these connections are keyed differently between the two boards. 1J17 has a key at pin 7, while the key on CN17 is at pin 8. The safest way to make a connection to CN17 with the 11C game harness is to remove pin 7 on the DE board. This will have no ill effect, if the DE board is to be placed back into a DE game. The worst case scenario if pin 7 is removed and the board placed back into a DE game is that the CN17 connector housing could be installed off by one pin, thus shorting the +5v to ground, and blowing the logic voltage fuse. 

[[File:DE MPU Jumpers for 11C.JPG|300px|thumb|left|Correct jumper setting on DE MPU for 11C game ROMs]]
[[File:DE MPU Special Solenoid Wire Swap for 11C.JPG|300px|thumb|right|Addition harness and Z-connector installed to correct special solenoid drive outputs]]
Next, the game ROM jumpers have to be set correctly. Since all 11C games use dual ROMs, jumper setting J4 must be in on the DE MPU, while J5 is out. Install the 11C game ROMS in the following positions. U27 (ROM 1) is to be inserted into the 5C socket, while U26 (ROM 2) is installed into the 5B socket. Notch on the chip / socket is facing to the right. There is an alternative method. The code for the dual ROMs can be burned into a [http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Burning_Dual_ROMs_into_a_Single_5C_ROM single 27512 EPROM.]

Finally, there is a problem with how DE boards poll the special solenoid drivers differently than 11C boards. Two of the drivers are correct (solenoids 17 and 21), while the four others are mismatched. To overcome this problem, either a harness can be created (DE board to 11C harness) with a Z-connector installed between 1J19 and the game harness, or the 7-pin housing (the 9-pin housing at 1J19 is split with a 2-pin housing and a 7-pin housing) at 1J19 can be repinned. The benefit of building a harness and adding a Z-connector is that it is easily reversible, if an 11C board is to be placed back into the game at a future time. 

The following wires will have to be connected to 1J19 / CN19 on the DE board for the game to function as intended.

{| class="wikitable"
!Pin Connection
!Stock Wiring
!Swapped Wiring
!Notes
|-
|1 || ORG-VIO || ORG-VIO || No change. This is for the flipper enable.
|-
|2 || ORG-GRY || ORG-GRY || No change. This is for the flipper enable.
|-
|3 || BLU-ORG || BLU-YEL ||
|-
|4 || BLU-RED || BLU-ORG ||
|-
|5 || Key || None ||
|-
|6 || BLU-YEL || BLU-BLK ||
|-
|7 || BLU-BRN || BLU-BRN || No change.
|-
|8 || BLU-GRN || BLU-GRN || No change.
|-
|9 || BLU-BLK || BLU-RED ||
|-
|}
 

=== Ball Will Not Kick Over to Shooter Lane at Game Start (Pinbot) ===
Trough and shooter lane switches test alright in switch test. Ball feeder coil from trough to shooter lane tests fine in solenoid test. If the motor for the visor is disconnected, and the visor does not cycle at the start of the game, the ball will not kick to the shooter lane. This may be an issue if one or both of the visor switches are not recognized too. Not certain what code revision this particular game was running.

=== Ball Will Not Kick Over to Shooter Lane and Drop Target Will Not Reset (Cyclone) ===
[[File:Cyclone UnderPF Fuse 1A 5A.jpg|300px|thumb|left|Fuse under the playfield of a Cyclone, which powers solenoids 1A and 5A]] 
Both the outhole solenoid (1a) and drop target reset solenoid (5a) are the only multiplexed 24v coils in Cyclone. The power wires for these coils are brown. For some reason, Williams decided it would be a good idea to put a fuse under the playfield for these coils (which is not included in the documentation). The fuse/fuseholder is located just to the right of the spook house subway.
 

===Special Solenoids Are Not Pulsed During Solenoid Test on System 9 Games===
The System 9 circuit board architecture provides no physical way to control the special solenoids other than via the enabling switch associated with the special solenoid device.

===CPU energizes a coil 5 times===
'''Police Force''' - After the pinball is switched on the ramp diverter coil engages 5 times. After the game start the diverter coil engages 5 times again. Diverter mechanism doesn't hold in position. So after the coil is energized the mechanism falls back and so the switch is closed again. Then the software tries another 4 times to resolve the problem. 

'''Resolution:''' Clean the diverter mechanism and in particular the plastic. Lubricate the plastic lanes!

===Elvira and the Party Monsters drop target reset coil blows the lamp matrix===
The drop target reset coil should be mounted with the solder tabs down. If mounted with the solder tabs up, (toward the playfield) the solder tabs can contact the J-A-M lamp sockets. This blows the lamp matrix ICs on the MPU board by sending coil voltage through the lamp matrix.