I have just picked up an X-Files with no sound. I have checked voltages going into board and all ok, and the voltage reg chip that the +5V and -5V are there. Looks like someone has tried to repair it as the chip socket had been replaced. If you put your finger on the capacitors next to the Amp's you hear a loud hum from the relevant speaker so confident this part of the circuit is ok. Have ordered new sound / music / speech ROM's so waiting on those in case they are the problem. Any other pointers or testing help much appreciated, I do have a scope; logic probe and meter to do testing.
Cheers
Brian