Trying to troubleshoot low-output issue on my Bandmaster...

[MarkSimpson]

This one just arrived last week, when I fired it up the output is exremely low - like a half watt. Swapped in a set of power tubes I know are good; problem persists.

Any possible scenarios that could cause this? I'm not an amp tech of any kind, just trying to get an idea as to problems that could cause this. Last time this happend with one of my amps (tweed Princeton), it turned out to be the output transformer according to my former tech.

[Fretts]

My 64 Super Reverb had that same problem. It COULD be any of 50 things, but on mine...
The tag board had become very wavy.. so wavy that it snapped one of the uninsulated, silver ground wires that go from the tag board to ground. Check that and see. You may have to look really close, or try to move each one with a pencil or chopstick to see if it broke loose.
Also it could be inaudibly high frequency parasitic oscillation, those are hard to trace down. Or a blown tranny, or a bad solder joint, etc
But check for that snapped wire first, it's a cheap repair if that's all it is.
BTW if you are really not an amp tech of any kind and you haven't been poking around inside amps for awhile, better to hand this off to somebody that is comfortable with these things. The high voltage stored up inside an amp can bite you so hard it will make you break out in a sweat and burn a hole in your skin, if doesn't kill you first. I've done the first two.

[MarkSimpson]

My 64 Super Reverb had that same problem. It COULD be any of 50 things, but on mine...
The tag board had become very wavy.. so wavy that it snapped one of the uninsulated, silver ground wires that go from the tag board to ground. Check that and see. You may have to look really close, or try to move each one with a pencil or chopstick to see if it broke loose.
Also it could be inaudibly high frequency parasitic oscillation, those are hard to trace down. Or a blown tranny, or a bad solder joint, etc
But check for that snapped wire first, it's a cheap repair if that's all it is.

Snapped wire/broken solder joint is easy enough to look for, thanks for the idea!

[Fretts]

Good luck! Work with one hand and keep the other in your pocket.