Hello, we have an Apollo 13 pin. The left slingshot solenoid went bad so I replaced it and the Q12 mosfet was shorted so I replace it as well. When I put the power board back in, the blanking light was blinking which I believe means the CPU board could not talk to the power board. I pulled and reseated the 20 pin ribbon cable, powered up and the shaker motor was going nuts. I then physically manipulated the ribbon cable a bit. Sometimes the shaker motor would go, sometimes teh left sling would fire and sometimes the moon would go round and round. I tried a different ribbon cable and the same result. I tested for other mosfet shorts and didn't find any, just q12 which we replaced. This seems like something on the CPU board, not the I/O board??? If I disconnect the ribbon cable all together, everything powers up okay (other than the blanking light blinking). I can't find details on the protocol between the boards. Could it be the upstream buffers??? What should I try next?

Tom

Yes, for the most part. I actually started having some strange behavior a while ago when I removed the CPU board to install a remote battery holder. When I replaced it, at first the blanking light was blinking. I bought a new ribbon cable, installed it and the led was solid and the game played fine for a while and then the sling solenoid blew and the bad q12 mosfet. The machine is at a lake house so I can’t look at it now. I believe ther is some corrosion on the male headers for the 20 pin connections. Best way to clean it? Do we think that is the root cause?