Any idea what's wrong with my 5150?

[Stones]

I've got a 5150II with a strange (fatal) problem. Whenever I turn it on, it powers up, all the valves light up, then about 10 seconds later they all turn off again. The amp does function for those 10 seconds, but it never has time to get up to volume anyway. All the power lights on the front will stay on regardless.

Any idea what this could be? Power tubes are brand new, pre amp tubes are pretty old. I just hope it's not the transformer

 

[Revson]

Bad capacitors maybe? Disconnect the power, take out the chassis and give it a look. See if the tops of any caps are bulging or even exploded, instead of being nice and flat. If you do this be careful not to touch anything on the solder side of the board as some of the caps could still be holding charge and shock the hell out of you if you happen to short one out with a finger. If you don't have any experience with tech work then I would just say take it in to someone who knows what they're doing.

 

[jeid]

Take it to a tech, could be any number of things. Worth getting a service.

 

[Stones]

I work in a music shop and have taken it to a qualified Peavey tech a couple of times now. We're in the process of eliminating possible faults, but as far as he can see there's nothing obviously wrong on the circuitboard (including the caps). Anything else it could possibly be? Thanks for the advice so far!

 

[jeid]

I'd have him check screen grid resistors

 

[MetalSound]

it´s broken. you can give it to me.

 

[guitarguru777]

Plug a cable into the FX Loop both inputs. Go in and out 3 or 4 times then fire the amp backup. The FX Loop tends to get corrosion on it. If its not that I think Screen Resistors are the issue.