Might be some kind of coin pulse multiplier or for a custom coin setup or for counting coin drops with hardware counter or something like that.

Gottlieb schematics are pretty well labeled. I would just try and reverse whatever they did back to factory setup.

coming soon

I have been busy on the computer =D. The first prototype actually boots and plays. That is a first for a board that complex, I usually screw at least something up, but also a testament to how good the original documentation was. I really like this system 3 hardware and learned some things from it I can apply elsewhere.

Heads-up about the mini fit jr connectors Gottlieb uses... they come in two PCB foot print row spacing sizes 4.2mm and 5.5mm. Gottlieb used 5.5mm row spacing. Make sure you don't buy the wrong ones *doh*.
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Driver board replacement is for sale $150 + ship.
https://nvram.weebly.com/gtb-system-3-driver-ma-1358.html
ebay.com link: itm

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You may have noticed Gottlieb put coil flyback diodes on the driver board much like WMS WPC games did. Except they did not stuff the diodes on the PCB and instead put the diodes on the coils. If you ever get curious, don't add them back in if your game uses the filter board. The diode and capacitor on the filter boards cause a voltage differential and all the filtered coils pull in you flip or other coils fire. Filtered coils in my soccer game was both VUKs and saucers.

replacement system 3 MPU $180

https://nvram.weebly.com/gtb-system-3-mpu.html
ebay.com link: itm

Some of those traces look like they could be severed.

I would knock off some of the corrosion with a wire brush to see where you are and then make a choice if you want to start patching traces or not. It is probably not worth the effort if a bunch have corroded open.

Your non booting game is probably not connected to the battery damage on the display board.

Knock off the corrosion. Get the schematic if possible. Dmm set to continuity buzz and check traces in areas of corrosion.

Good visual inspection goes a long way too.

Maybe try audit 18 to novelty mode. I am guessing this game does not have the tournament mode switch? That is normally how you turn off extra balls.

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15 balls per game sounds like the memory is corrupt, that should be impossible.

Open the coin door. Push the diag button on the left side. You will get a list of options on the dmd. i forget which one you want to pick exactly, but I think the first step of adjustments will ask if you want to do a restore factory settings. Say yes.

Then get back into the test mode and you can choose your options. It will probably default to three ball.

his new driver board should have a yellow voltage indicator LED in the top middle, make sure that is turning on.

The LEDs on the driver board are just voltage indicators. I think you have one for logic, lamps, and solenoids.

If you have tried two driver boards and new ribbon cables with the same result, the game is likely not communicating properly to the driver board. I think I received your exact symptoms once by bad ribbon cable between the MPU and driver. Game would boot, display showed stuff, but nothing worked, no switches because they drive them from the driver board. In that case it was the ribbon cable was bad. I put a new one in and it started working again.

On the MPU side inspect the ribbon cable pins. Make sure none are bent over. No solder joints are cracked. If you have a logic probe, power up the game and check that every data bit and signal at the MPU ribbon cable pulses like it should, having a spare MPU helps to compare to if you are unsure exactly what each signal should be doing. BD0 - BD8, LDATA, LTSB, LCLR, !MR, LDS important signals leaving MPU J2. I think is !MR signal is floating the driver board will act dead. MPU U14 enabled MPU U7 to send all BD signals to the driver board. I would make sure that is working.

Yes they use the mini fit Jr connector system. These connectors are quite robust. I have some i have cycled hundreds of times and still seem to be okay. Unless you have some plugs cut off, smashed or burnt they are probably okay. Same kind of connectors used on computer mother board and some vlideo card power connectors

If you do replace the pcb socket side keep in mind they are sold in two row spacing, 5.5 vs 4.2mm. You want 5.5mm. The wire side plugs are all the same sized and universal.
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System 3 audio amp aux power supply. MA1722 has an op amp and some extra circuitry that MA1605, the same board, does not. JP2 and JP3 jump over the missing op amp. This board could have stereo, but pretty sure for all games they just mix both channels together (JP1) before the two amplifiers.

Made a replacement pcb. Haven't tested it yet as a MA1605, but it MA1722 should replace MA1605 if you just change the jumpers an remove the op amp. I think the rest of the parts can stay in.

Quite a few dc blocking caps are jumped out on the original board. I suppose they decided it was not needed.
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