http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Useful_Sound_Board_Repair_Links. Could be a lot of different problems. if you hear a hum from speaker than its probably ok you can try turning the volume control to see if you hear anything, turn the speech sound mixer to see if it changes anything (usually it's set somewhere in the middle) reseating connectors to see if it changes, check female ends of wire connectors for bad/worn crimp contactors, while on and game playing press on connectors while plugged in to see if their is any change, could have cold solder joints on boards. Check out the link for a bunch of suggestions.