Arcade Collecting > Pinball
Anyone here have experience in repairing williams pinball machines?
dansoftcore:
I mite order that after I take the board out and check out the solder joints and such I believe the 12v for the cpu board is the top plug? Above the heatsink
gibbous:
12V is coming in to the CPU board at 1J17 I think, near the battery and the sound diagnostic switch. I think the two pins closet to the batteries are 12V, furthest out is +, next one in is -.
I've got a Space Shuttle with similar problems. But on mine the 7 never goes away, and I've ruled out the PS as a problem. Verified the ROMs (which is the other thing the repair guide says could be wrong) and I've found a bad chip at U3. Have to get a replacement and see what happens from there. If I'm reading the schematics right (still new to this), U3 tells U23 to pass the ROM data to the CPU, which would account for a ROM error if it didn't work.
dansoftcore:
Maybe mineis the rom... I'm getting 12v on the cpu board and powersupply... Where do you plan on ordering your roms?
gibbous:
I'm lucky I have a buddy that did it for me. Didn't help though. :(
http://www.hobbyroms.com/ might be a good place to go.
At least part of my problem seems to be that I'm loosing a volt going from pin 14 to pin 13 on U3, and they should be the same voltage. As I understand it, this is the CPU trying to read the ROMs. Swapping the chip at U3 did nothing. I'm tracing the problem to all the other chips it touches now looking for something that's bringing the voltage down. There's a bunch of them.
BTW - Ed at EdCheung.com will sell you working System 9 boards or fix yours. I'm going to try to fix mine first (hopefully not doing more damage!), but it's nice to know the option is there.
dansoftcore:
I noticed mine is dropping voltage as well it isn't much just about .4 off.
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