No sound on Mortal Kombat II

[vizzinni]

 I've lost the sound on my Mortal Kombat II game. There's a bunch of posts here, at KLOV, and other places about sound problems with this game but none exactly like mine.  Here's the background and what I've tried.

It's a Williams DCS sound board (part# A-17319-40029), but it appears to be different from their pinball DCS board.

When I first brought it home a week or so ago there was some (weak) sound, but I had to max the volume (through the service menu; there's no vol pot) to hear it.  After a couple on/off cycles as I worked on other (monitor) issues, maybe a total of 30 minutes of running time, the sound disappeared completely. 

There's no hiss or any other sound coming from the speakers.

There's an LED on the sound board that is lit.

The voltages at the JAMMA harness/board connection are correct.  The speaker wires are tight at the JAMMA harness and run to the speakers without interruption.

The ribbon cable between the main board and the sound board tests OK.

The power harness between the main board and the sound board is good on voltages at the sound board side, except that the 12v lines are providing 13.95v or so.  The 5v and -5v are almost right on.

I've removed and reseated all the sound ROMS on the board.  Pins looked good, with no corrosion.  I haven't done anything with the main board.

I don't have a logic probe, so I'm limited to standard multimeter troubleshooting.

The fact that there was at least weak sound at first makes me wonder if something on the sound board, like a cap, gave up the ghost after getting powered up after a long break.  There's no obvious cap damage.

Any ideas? If not, who repairs these things?