Response from Jonathan: Jeff,

It sounds like your monitor is experiencing an issue known as hum bar. This can be caused by a number of things including grounding issues with your monitor chassis/frame, bad caps, bad fuses/fuse holders, etc. We would start off by making sure that the monitor frame is connected to earth ground (i.e. the round prong (green wire) on your main power plug). You might also try Installing A Cap Kit as bad caps in the AC section of your monitor chassis can cause this issue. If this issue is in an older game such as Pac Man, Ms. Pac Man, Centipede then you might try replacing the fuse holder in the bottom of the game as this has been known to cause this problem as well.

In our experience, proper grounding in your arcade cabinet really seems to be the key to solving this issue. Start by solving your grounding issues then work from there. Hope that helps. Thank you for your question and good luck with your repair.