I'm working on a project Centaur and it has several bad chips. The previous owner said it was working then quit one day. On the MPU it had a bad processor, both PIA chips and 6810. The ROMS were already replaced. On the lamp board 2 chips were bad. I'm thinking the 5V was spiked. Any ideas on what could cause this? The voltages all check out good on the rectifier board. I do not have the solenoid driver board that was in the game when this happened but it went bad too.
Normally when someone puts 12v down the 5v rail in a bally game U15 on the MPU explodes, maybe the eproms and RAM fail, but the fuse usually blows before it is catastrophic. U15 seems to always go, so if your MPU u15 is bad, I would really suspect over voltage got on the 5v supply.
The 43v is also one 0.1" connector pin away from +5v on the J4 plug. Corrosion will fester there giving a slow arcing burn out.
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Boise, ID