Sound board and cable are known to be good. When I power up, I get a loud hum, and volume changes when I adjust the pot. I get no game sounds in test or in game play. I believe that the sound that is present and changing volume rules out the speaker and the pot as cause for the problem. Is that a valid assumption?

I think the next step is to rebuild the female connectors on the lower part of the board.

OK, confession time. Yes, I'm aware of the issues with connections between the sound board and MPU on early Sterns. If you have one big connector, you have to rotate 180 degrees to get the pins to line up right. With two connectors, it can be confusing, and if you have an alltek board in, it's even more confusing, because there are extra pins. I KNOW all that, that's why I was so careful to make sure I connected everything correctly.

So, when rebuilding the lower connectors didn't fix it, I went back to check the thing that I was 100% sure of...

To make a long story sligtly longer, someone clearly monkeyed with the MPU connectors, because they were not aligned correctly.

I blame ISIS. Or El Nino.