I got an old kustom charger amp for free, when powered up it hums and squeals if you try to turn up the volume or eq controls. I pulled the head unit, opened it up and found it has been soldered on in places. The power cord and switch seems to have been replaced, when I have my hand on the switch and chasis or swich and strings this goes away and it sounds fine. The amp has a power switch that says polarity then on in 2 directions. My thought is aground concern with the switch. What if I replaced it with a modern simple on/off switch and grounded it and the chasis?
