I have an AFMr CE. It's newish to me....
I have a feedback/buzz that comes through the speakers. It seems to be in sync with the back of LEDs.
If I unplug the back box from the boars the noise goes away. But once plugged in the noise is back. I'm certainly not a pro, but seems to be electrical interference of some kind.
I tried putting the back box cable through a isolator thingy that I had but no change at all.(see pic) I tried unplugging each individual LED on the back box but no single one was the culprit.
Game is still playable - its just annoying to listen to.