Response from Jonathan: Bob,

While this kind of sounds like a monitor issue, it’s probably a good idea to check some other things before making that assumption. We recommend starting off this repair by checking your power supply to make sure that the voltages are correct. Strange issues like this are common when the board is not getting the correct voltage. Check out our posts on Checking And Replacing A Power Supply and Checking A Classic Power Supply for more information.

Also, check out your wiring to make sure there are no loose wires or pins that might be making contact with your cabinet and creating a short. Best way to do this is to start at the AC wire and make sure all of the subsequent wires are connected properly. If the problem continues to occur after you’ve checked the voltages and wires then the problem probably lies in either the board or the monitor.

I’m really leaning towards a monitor issue at this point because you said the game continues to play with sound even when the monitor goes off. This is a phenomenon we call “playing blind.” This is a very common issue with arcade games and we discuss it in our post on Troubleshooting Games That Are Playing Blind. While our post goes into some detail on different parts to replace, it sound like you just have a cold solder joint on your monitor chassis. You might try just touching up the solder on the monitor board to see if that makes a difference.

Hope that helps. Thank you for your question and good luck with your repair.