fender stage 100 amp buzzing

[Rev]

I've got a fender stage 100 amp thats buzzing when you power it up. You plug a guitar in it still buzzes but you don't hear guitar any ideas.

[Andrew58]

could just be a broken ground connection on an input jack, or some other open ground connection. something that simple. Is it like a sharp buzz or low frequncy hum as in shorted filter caps? when you knock on the amp does the buzz change some how like there could be a lose/broken componet or a cracked soder joint.

[Enzo]

Or broken solder on the main filter caps.