Quoted from mark9:
Yes,the toggle switch that's labelled "Mute,Disable,Enable".
I've tried removing the Pinnovator board from the coin door to make sure the jack is seated properly. Also tried the ethernet cable connections at both ends and between the main metal box and the sound board.
The volume buttons on the board seem to function in that they turn the leds on and off as they should, and you can hear a small pop through the headphones when you press them.
The only thing I can think of is to bypass the headphone jack in the door.
Plug headphones directly into the headphone jack on the back of the computer, Its probably blue where as the speaker mains are probably green if they havent been bypassed.
Also check if all of the RCA cables are fitted correctly on the computer.
Some cables also run thru the silver computer cabinet onto the sound board on the PC. Check those also by unplugging and then reinserting. Make sure all of the cables are firmly seated in all areas while you are there, Both on the outside of the case and on the inside on the boards.
If you can get sound in headphones directly off of the computer headphone jack but not at the door panel then its a wire problem or a problem with the fitting on the door.
The pinnovator door board plugs into the computer also. You can trace the wire back to the PC.