PVX P12 Loud Hum Issue

[Denny740]

I have a powered Peavey Speaker - PVX P12
It has a very loud sound constantly coming out of it - like an open ground hum - no way to alter the sound - it’s always there if it’s on.

When I unplug the Input PCB, the sound goes away. I’m thinking there is a problem with the Input PCB, but don’t see anything obvious and no way to troubleshoot it without a schematic.

Obviously, the Speaker, Horn & Power Amp are all working since the sound is loud.

1) Is there a way to get a schematic? OR
2) Should I just order & Replace the Input PCB? OR
3) Should I find a Service Center? OR
4) Any other ideas?

Thank you in advance,
Denny

[Pappy B]

sounds like a bad capacitor or maybe a bad solder joint. Most of the time bad capacitors look fine but sometimes they can be spotted by the top of the can bulging or even split.