Well I replaced the caps and amps and still have a problem. I do now have volume, so that part is fixed.
I attached a couple pics. The line I am pointing at on the soundboard goes to the MPU board where I am pointing in the other picture.
Anyway, if I unplug the wiring that I am pointing at on the soundcard or at the MPU, the buzz goes away, but of course it loses some of the sound effects (I was listening to it in attract mode).
Anyone have any ideas? Could the wiring between the MPU and soundcard be bad? Is there any way to test this easily? If it's not the wiring, could it be the amp on the MPU, or the caps right by where the wiring plugs into the header on the MPU?
Thanks again!
Edit: OK, for the ongoing saga... So I decided to try and run some jumpers from the MPU board to the soundboard. This seemed to get rid of most of the hum. I had plugged/unplugged the cable several times and I can't tell for sure, but I think it helped the humming. I suppose it could be corrosion on either the header pins or inside the female plugs. I will give them a good cleaning today and see if it helps anything. I am really thinking though, this has to either be corrosion on the headers/plugs or else the wires are getting feedback of some sort from the other wires, causing the hum. I will try cleaning contacts and if that doesn't work, I will have to seperate the wires from the other wires and see if that helps.
O.K. I think I got this figured out. I cleaned the headers and female connectors again, still had the hum. So, I took the wire out of the harness and ran it away from other wires. Hum stopped. So, if I am following the right logic here, the wire from MPU to soundboard is getting interference from the other wires.
So, any ideas what to do with this? Could I wrap the wires in foil tape or would that make it worse? I am thinking that would act as a RF shield and cancel out the interference.
Another EDIT: Yikes! Got to looking and this has no ground plug, somebody in it's past snipped it or pulled it out. That may have had something to do with it, but... not sure as the above stopped the hum.