How to find ground wire on monitor?

[pcm2a]

I am trying to pinpoint a ground loop issue causing buzzing in my speakers, in a devil zone cocktail. If I unplug my monitor the issue goes away. I am not sure which wire is the ground wire that I need to be testing with my multimeter.

[lilshawn]

all that which is metal surrounding the tube and chassis is ground. it should be connected directly to the ground pin of the plug. in fact ANY metal should be grounded...the metal doors, the hinges, all of it. this is from a safety standpoint. you don't want live voltage from a crunched wire in the hinge to make the hinge charged to 120 (or 220 depending where you live) volts and killing you when you touch it.

i think you have an induction issue. in that, the high voltage currents flowing through the monitor are causing noise "wirelessly" to be generated in the audio system.

ensuring the audio wires are properly connected and shielded are a good first step. check any wires routed to a volume knob (as well as the knob, are as far away from the monitor as possible.

[pcm2a]

The audio board plugs into the game board, which is mounted on the cocktail door. As you close the door the audio board gets closer and closer to the monitor and once closed it is real close. I tried various suggestions from KLOV, like a faraday cage, with no success. In the end it cost $7 for this ground loop isolator, which has removed 95% of the buzz.

The ground wire of the plug connects and jumps around to every piece of metal in the cocktail. However, I never was able to pinpoint a jumped wire to the monitor chasis. There are quite a few areas that I am unable to see, so it's possible it's there and just not visible.