I sold a Williams type 1 sound board to a customer for use in his World Cup. It was a working board that I pulled from a Tri Zone. Other than re-flowing the solder on the header pins I didn't do anything to it.
Customer installed it, said he was seeing the same problem as before, just a loud hum. Here's what I had him do to troubleshoot it, and the results:
Checked to see if the two 4-pin connectors were installed correctly. They were.
Tried individually grounding the pins on the upper left connector (J3?) to see if it would produce sounds. Nope, just the loud hum.
Checked voltage at C29: 10.6 volts
Checked voltage at C30: -12.5 volts
Checked voltage at C27: 5 volts
Tried it with a different speaker and speaker wire, no change.

This game doesn't have a remote volume control so it has the jumper plug, and it is correctly installed.
Game has a new Rottendog power supply.

What in the hell am I missing here???

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