1-slot from hell returns....

I got a 1 slot board that doesnt output any sound (just humming). I really dont know what the problem is. I mean, it cant really be a fried chip, otherwise I'd get an error message. Alot of people told me it's the sound amp, but I dont know... Is it easy to repair? I'm trying to either sell it or use it, but I'm not really willing to do either until it's working properly.
So can this be fixed?

Are you talking about the Mono sound from the JAMMA connector, or the separate stereo sound connection, or both?

I get no sound whatsoever, not from the jamma connector, or from the stereo/headphone pins.