Princeton Reverb RI volume cutting in and out

guitarblaster

Hey guys, I noticed yesterday the volume on my Princeton Reverb RI was cutting out every now and then, like a big volume drop and then it comes back in. It can the be fine for a few mins and then do it every 20 seconds or something. So quite random! I did a quick google and it seems it might be the power tubes? I've tried changing cables and going straight into the amp - same thing! 

Any held appreciated! Thanks! 

ICBM

The one thing it's pretty certain not to be is power valves! If one was intermittent then you would notice a *small* volume drop, not that large unless the amp was really cranked up. It won't be both with the same fault at the same time.

It could be a preamp valve problem though. To test that you need one spare 12AX7 - it won't be the 12AT7, which is just the reverb driver.

Does it cut in and out instantly, or fade in and out over several seconds?

If it's quick, check the speaker connections - they use push-connectors which in my experience can be unreliable. Not usually on newer amps, but still occasionally. Also give the speaker plug into the back of the amp a wiggle, sometimes the contacts can get dirty.

If it's not that, or if it's a slow fade-out, it's likely to be a connection problem inside the amp, probably one of the connectors from the power amp to the PCB.

guitarblaster

Thanks so much - it's amazing you share your knowledge so freely. 

I would say it fades in and out rather than a cut out completely - like I could play for 5 seconds at a reduced volume kind of thing. 

I just pulled out the speaker plug and put it back in and randomly touched the speaker connectors because they look fine - I played for about 15 mins and no cutting out! The past 3 times I've played it it's been cutting out! So ... despite being a fade in and out over several seconds thing, maybe it has been cured?

Hah I'll find out tomorrow, a bit late to be playing now!

Thanks for the help!