Firepower 2 (system 7) sound issue. So I was playing a game yesterday and mid game all the sounds started being wrong, not incorrect times, like weird not normal not typical sounds. In addition, the background sound went away completely. It was odd sounds I’ve never heard when the ball hit things, and they would linger forever until something else got hit and then that would be the incorrect sound too.

Things I’ve checked so far…...
Voltages are all correct and solid (I recently rebuilt the power supply if it matters), connections and plugs are good, sound board has been rebuilt recently by Eugene Mosh so it appears all the caps have been replaced and headers re-flowed, all grounds are good, and all the screws are in all the boards and tight. If I go through the sound test using the coin door the sounds are incorrect. If I disconnect 10J3 from the sound board, and push the test button on the board, the test sounds are correct. If I ground out the pins on 10J3 I get the correct sounds. So I’m assuming my sound board is good. So I moved on and checked continuity on the harness from the MPU to the board and it is good. I haven’t pulled the MPU to check for cracked header pins at 1J8 yet, and I’ll likely re-flow them regardless when I pull it just for GP.

So I’m THINKING, best case it’s cracked/cold solder joints on the MPU header pins at 1J8 (but I feel like wiggling it a bit would have made that apparent). Likely I think it’s PIA 5 or IC37 on the MPU.

I’m a system 11 guy so I’m kinda pulling at straws here, so can someone lead me a bit in the right direction?

Thanks!

Nice! Gonna dig into it tonite, gonna start simple hopefully that's all it is.

Update....everything suddenly came back to life for about one game and sounded correct and then crapped out again. Now all the tests with the mpu disconnected are the incorrect sounds too (grounding of the pins and the on board test button all produce the wrong or no sounds at all). So I'm leaning towards the sound board now......any suggestions? I usually like troubleshooting, but when it's this weird and inconsistent I'm starting to think about sending the board off vice shotgunning parts at it.

Turned out to be a bad 6802. Easy fix, up and running again!