Stern S.A.M. System Repair
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1 Introduction
S.A.M. is the current board system used by Stern Pinball. The first full production game to use the S.A.M. Board Set was World Poker Tour in 2006. One of the features of the S.A.M. board set is that the software can be updated with a USB stick.
2 Games
- World Poker Tour
- Pirates of the Caribbean
- Family Guy
- Spider Man (Stern)
- Wheel of Fortune
- Shrek
- Indiana Jones 4
- Batman (Stern)
- CSI: Crime Scene Investigation
- 24
- NBA
- Big Buck Hunter Pro
- Iron Man
- Avatar
- The Rolling Stones (Stern)
- Tron
- Transformers
- AC/DC
- X-Men
- Avengers
- Metallica
3 Technical Info
3.1 The S.A.M. Board Set
The S.A.M. System board set consists of three boards in the back box. The CPU / Sound board, I/O Power Driver board, and the Display Power supply. Later SAM games which use LED dot matrix displays do not use a display power supply.
3.1.1 SAM CPU / Sound Board
- The various generations of the Stern SAM CPU board
Stern first generation CPU/Sound Board 520-5246-00 Revision H (up to Tron).
The adaptor is not part of the CPU. It's used in the Whitestar test fixture
Stern first generation CPU/Sound Board 520-5303-03 Revision H - Modified with Limited Edition Code(Tron LE) 
Stern second generation SAM CPU/Sound Board 520-5246-02 (Transformers and forward). The USB controller chip on this board changed to an FTDI VNC2-48L1B - Vinculum-II Programmable USB 2.0 Host. This is the AC/DC version of the board with 2 64 MBit flash roms 520-5337-00 
Another Stern second generation SAM CPU/Sound Board 520-5???-?? (Star Trek Pro). To make life for operators, repairmen and collectors easier Stern released another version of this CPU with Star Trek Pro. It seems to be identical to 520-5337-00 but only has one 64 MB flashrom.
Up till now there are five versions of the SAM CPU/Sound board. The first one had several minor revisions over it's lifetime but they can all be used in all games up to Tron. The first revision of this board used in World Poker Tour only has an USB 1.1 compatible USB controller. Finding USB sticks which work with this revision can be tricky. If you own this game see that you can find an old 32MB stick. They usually work fine. Second one uses the USB 2.0 revision of the Atmel AT43USB380 chip.
Starting with Transformers the USB controller became unavailable and was replaced with a different chip. That makes three. All these boards use a 32 MB flash rom. With ACDC space was running out and two 64 MB flash roms are used. To save a few bucks it looks like starting with Star Trek some Pro modells will be fitted with only one 64 MB flash rom.
The LE and Premium models use variations of these boards. The programmed chips on them are different. They are not interchangeable. Trying to use Premium software on the Pro or vice versa is not possible. A hardware mismatch message will be shown. For a complete list of games with their board numbers see Stern Service Bulletin 178. To make things worse the boards for 50 Hz countries are programmed differently to prevent cheaper direct imports from the US so this essentially doubles the variants. Thank you Stern. NOT!
The SAM system is now almost at the end of it's life. A completely new system has been developed, and it is believed that it is currently being used in the Stern home model pinball machines referred to as "The Pin". This new platform will eventually be used in all Stern pinball machines.
3.1.2 Power Driver Board
Power, fuses, bridge rectifiers. GI relay, coil and flasher drivers.
The adapter in the pic on the left is not part of the board and only used on the Stern White Star test fixture.
Starting with the LE and Premium edition games Stern now uses a new driver board. The lamp section in the lower left corner of the board has been replaced with a programmable Xilinx FPGA controlling the LED lamp boards. Due to this set up, 18vdc is no longer needed, nor is it present for controlled incandescent lamps. The 5V section has been completely overhauled also.
3.1.3 Display Power Supply
The SAM games equipped with gas plasma dot matrix displays use the same 520-5138-00 Display Power Supply as the Sega/Stern White Star games.
3.1.4 128 x 32 Dot Matrix Display
All US Stern SAM games up until, but not including all versions (Pro, Premium, and LE) of AC/DC use a 128 x 32 "standard", plasma dot matrix display (part # 520-5052-00). Because of the RoHS law European models from POTC to Family Guy use a modified Pin Led DMD. Later games use a 520-5052-05 Red LED DMD. Starting with Transformers, Stern games use a low voltage LED 128 x 32 dot matrix display (part # 520-5052-15). It's exactly the same as the -05 variant but uses brighter LED segments. The LED dot matrix displays are comprised of 64 discrete 8 x 8 LED matrix displays. With AC/DC, Stern also started to use LED DMDs in US models, completely phasing out the use of DMD Plasma Displays in their games.
- Stern Red 520-5052-05 LED DMD
- Stern-520-5052-05-Front.jpg
Front 
Back - Stern-520-5052-05-Segment.jpg
Close up view of the LED matrices used on the LED DMD
3.2 Recommended Documentation
As always, it is highly recommended to possess a game manual. Every game manual is full of detailed information regarding game specific switch, lamp, and coil assignments. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended pinball parts suppliers.
Since Avatar Pro Stern no longer includes printed manuals with it's Pro models. You usually get a few sheets of junk they call documentation but it's insufficient if you need to repair your game. The yellow section is mostly absent and schematics for newer boards are not included or useless photocopies (see AC/DC LE pdf files). Good luck if you have a problem here. You can only hope this changes again because the Pro modells are targeted to operators.
The Stern Pinball, Inc. website currently archives game manuals using the S.A.M. in part or in whole in PDF format at the time of this writing.
Stern Pinball also makes Technical Service Bulletins available on their website here. There is an option to search by game title. The archived service bulletins (pre-2009) are here.
3.3 USB Code Update
Note: this information can be found on the front inside cover of S.A.M. System Game Manuals, or at Stern's website here.
Step 1) Open the Back Box
Step 2) On the CPU/Sound board set Dip Switch #8 to "ON".
Step 3) Press the white Reset Button (S1 RESET) or power cycle the game.
Step 4) The DMD should show the current software version installed. Press the "SELECT" button on the inside of the coin door to continue.
Step 5) Highlight the "UPDT" icon on the display and press "SELECT".
Step 6) The game will prompt you to insert the USB Memory Stick.
Step 7) Pick the correct file on the USB drive and press the "SELECT" Button.
Step 8) Follow the directions on the display.
Warning: If you live in a country with a power line freqency of 50Hz like any one in Europe do not update your game code when turning the game on for the first time ever. As of today 2012/06/29 there is a bug in either the system or update code. Doing so will usually wipe out the country lock code from the game and the CPU needs to be exchanged. See Stern Service bulletin 170. Let it stay in attract mode a few minutes or play a few games with the old software first. This has been observed with a Batman Dark Knight and ACDC/LE.
3.4 Accessing Bookkeeping, Settings, and Diagnostic Modes
3.5 The New Stern LED Lamp System
Stern developed a new serial lamp control system for the release of Tron Limited Edition. This system uses a serial protocol to control playfield LEDs.
There are three components to the system
- the serial bus, which carries clock, data, power and strobe signals
- lamp boards, typically strips, which carry a serial LED controller for on-board LEDs and satellite LEDs
- LED satellite boards, which solder to the lamp boards.
The lamp boards daisy chain. Therefore, the controller can feed, say, 8 bytes of serial data to the lamp boards and strobe the data in, turning on or off 64 LEDs. This system is potentially expandable to hundreds of controlled lamps, breaking the constraints of the traditional lamp matrix. The lamp boards and LED boards can be assembled outside the game,simplifying the production and assembly of the wiring harness.
The controller used is an STP16DPS05. This device controls 16 LEDs, and uses a constant current output. Therefore, it needs no current limiting series resistors, although Stern has implemented series resistors on the satellite boards. [any ideas here?] The driver is also capable of reporting short and open LEDs, but it is unknown if Stern has implemented this feature.
In terms of diagnosis, one failed board could disable the entire system. The STP16DPS05 is a likely candidate for failure if an LED satellite board tangles with GI or other voltages. Replacing the chip is tricky as it has a full-contact heat transfer pad on the underside, which is difficult to heat properly without hot air or IR equipment.
It may also be useful to have a z-connector to hand to bridge out a failed board. This will result in incorrect light patterns, but will at least demonstrate that the system is driving the daisy chain.
4 Problems and Solutions
4.1 Power Problems
4.2 MPU boot issues
4.2.1 Relocating the battery from the MPU board
The Stern S.A.M. system uses a single 3v lithium CR2430 "button cell" for its memory backup. These cells have very long life and are not prone to electrolyte leakage so you do not need to do this.
4.2.2 Connecting a logic probe to the MPU
4.2.3 Using a PC Power Supply For Bench Testing
4.3 Game resets
4.4 Solenoid problems
4.5 Lamp problems
If you have a bulb not working, seat the wiring into the IDC type socket better. I've run into a lot of these where the wires aren't seated and making good electrical contact.
4.6 Switch problems
If a switch isn't working. The three most common things I've seen is. 1- crappy switch, even if new. 2- if wires go into a IDC connector nearby, be sure they are seated good and making electrical contact. 3- broken wire at switch, or inside casing or harness, easy to quick check continuity of wiring.
4.7 Display problems
4.7.1 DMD LED to Plasma conversion
Starting with Pirates of the Caribbean Stern replaced the normal Plasma Dot Matrix Display on European modells with an LED variant because of the RoHS law. They first used Pinled DMDs and later switched to a red DMD specifically made for them (520-5052-05). The debate which looks better will be going on for your remaining lifetime and continue right into you next few lives but here we show you what you need to replace your LED DMD with a standard Plasma Dot Matrix Display.
The following parts are needed:
- 1 x 520-5138-00 Stern Display Power Supply Board
- 1 x 036-5454-01 SAM DMD Display Cable
- 1 x 535-9769-00 PCB Metal Mounting Plate (Display)
- 1 x 830-6053-00 Plastic Cover Danger High Voltage
- 2 x 254-5000-05 1-1/4" x 3/8 Plastic Spacer Grey
- 2 x 237-5975-00 #8 x 3/8 SHWHSec (Zinc) Screw
- 2 x 02-4425-2 Machine Post/Stud standard metall threaded posts with #8 bottom and #8 top (for the gray spacers).
- 2 x #8-32 Nylon Insert Lock Nut
- 4 x #6 x 1/2" Wood Screw to mount the unit in the backbox
You can get all these parts from your favorite pinball dealer. I got them from Pinball Life. If they are not on the web page ask.
You need to first assemble the High Voltage unit. Assembled it looks like this one here:
- Stern SAM High Voltage Unit
View 1 
View 2 
View 3
Just screw it into the backbox of your Pinball over a ground strap:
The cable which goes into the left side is somewere hidden in the wiring harness of your pinball:
The LED DMD plugs into your wiring harness with a 2 pin connector. You need to remove the connector and connect the 5V line to you DMD HV unit. You should find the corresponding 2 pin plug which matches the one on the picture nearby. Warning: the wires should be red and black. At least in Family Guy and Shrek there is a similar connector with 2 brown or black wires with color stripes nearby. This one is for the optional knocker kit. Make sure you do not connect this one to your DMD 5V line. Doing so will take out the DMD and the SAM CPU beyond repair! If unsure measure the voltage on this connector first.
If your game uses a Pinled LED DMD a small pcb is connected to connector J5 on the SAM CPU. Take this one out and install the ribbon cable directly in J5 on the SAM CPU. Now you just need to replace the DMD with a standard plasma DMD and voila ist should work.
4.8 Sound problems
In early SAM games if you have the simulated knocker activated the sound may go to full volume after you get a replay. This is a bug in the operating system code part. Fixed in newer games but Stern didn't release updated roms. Observed in FG and Shrek. Workaround disable the simulated knocker and if you want the sound put a real one in (the games support it).
4.9 Flipper problems
Coils hum. The way they are power cycled causes some of this. I've also found that they get noisier with use. I then file the plunger end smooth, and the top of the coil stop smooth, where the plunger hits it. This helps a lot with noise.
4.10 Pop bumper problems
4.11 Opto problems
4.11.1 Opto board 520-5292-00
If you have trouble with you switch matrix check the little board. It's installed in at least Batman Dark Knight and AC/DC. In AC/DC a bad board can give you problems with at least the bell and the right pop bumper. If the pop bumper turns on when you shoot into the bell the board is bad.
Not much on the board. If you have general switch problems the likeliest candidate is Q1 a BSS123 in a SOT-23 case (small) transistor. Check it with you DMM. It's a Mosfet so can not be completely checked with your DMM. On the defective board the drain to gate pins were practically shorted.
If your opto interruptor just doesn't work you can replace it with a QVE11233 from Fairchild. It's the standard opto for WMS flipper boards so a replacement should be easy to get. Stern also used a chinese substitute OS92B4. Not much can be found about it.
5 References
SAM system schematics are available on the Stern Pinball website here: http://www.sternpinball.com/schematics.shtml
6 Game Specific Problems and Fixes
Stern opto boards at end of trough. And boards playfield optos plug onto. I've noticed when problems arise, to reflow the solder on the optos, and pins the connectors plug onto. This eliminates a lot of problems that arise with the optos. LTG :)
Pirates of the Caribbean. The spinning disc. Check your serial numbers with the service bulletin on Stern's website. Some of the early games need to have the bearings lubricated.
And if your artwork is worn off. I've found when you put on a new decal. To put clear non-slip bath tub stuff on top of it. It works just as good at flinging the balls. And doesn't wear off as fast and get messy all over the game like the original. And easily replaced. LTG :)
7 Repair Logs
Did you do a repair? Log it here as a possible solution for others.
If you have feature lamps not working. Check the wiring pushed into the lamp socket. I've seen more than a few where the wire isn't making good contact where it is pushed in. Easy to push in better. LTG :)