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'72 Princeton Reverb problem... help!

pedrohead

Member
Messages
175
So I just picked up a Princeton Reverb this evening that had basically been sitting in a closet for 30 years (it's true, it really does happen).

I turned it on and once you get the volume above about 2-3, horrible static/farting bursts start blowing through the speaker. I was thinking (hoping) it was just a tube problem. You could tap on the pre tubes and occasionally that would start light static noise (or stop light static noise) and some it was like hitting a tuning fork and a shrill tone just shot out of the speaker (with the volume all the way off).

I swapped out the preamp tubes en masse with some that I know are working, and the problem was still there (not as much with the microphonic tapping, but loud bursts of static that were only there during playing over 2-3, especially with bassier notes). I plugged the speaker into another amp and the speaker seems ok.

I took some 6V6 tubes out of an old Deluxe that I have (these tubes are likely even older though...) and didn't help. And didn't have another rectifier tube like this amp had.

Does this sound like a power (likely not) but maybe rectifier tube problem?

Anything else I can do to try and diagnose? I don't have a good amp tech too near me and would like to eliminate some easy possibilities before paying a bunch to go get it fixed somewhere. Thanks.
 

hathisisfunnyha

Silver Supporting Member
Messages
1,990
take it in to amp tech. it sounds like it needs a thorough cleaning and checkup. also check to make sure the speaker is unharmed.

i just dropped my 65 princeton reverb off to get a full checkup, and hoping that it has minor issues versus major.

the more you play it in a dilapidated state the more damage you can cause
 

pedrohead

Member
Messages
175
take it in to amp tech. it sounds like it needs a thorough cleaning and checkup. also check to make sure the speaker is unharmed.

i just dropped my 65 princeton reverb off to get a full checkup, and hoping that it has minor issues versus major.

the more you play it in a dilapidated state the more damage you can cause
Yeah, I hear you. I'm just hoping to get anything obvious or cleaning out of the way first.

Any other ideas?
 

slider313

Gold Supporting Member
Messages
8,269
The electrolytic caps in the amp are 37 years old. You are in dire need of a cap job.
 

slider313

Gold Supporting Member
Messages
8,269
Thanks for the input. Do you have any idea what something like that typically runs on an amp this size?
Typically between $150 and $250 for caps and a complete service which would include cleaning tubes sockets,pots,grounds,input jacks,switches,checking for leaking coupling caps,bad tubes,solder joints and making sure all resistors are in spec.
 

Blue Strat

Member
Messages
30,192
Try cleaning all tube pins and sockets. Check the FAQ on my website under RESOURCES. Bad connections, sometimes tube related, are a very common cause of the symptoms you're experiencing.
 

pedrohead

Member
Messages
175
Thanks guys. I had actually gone in this morning and cleaned all the pots, input jacks, tube pins and tube sockets, and it seems to have gotten a little less noisy, but still the same loud bursts of static if playing a bass-ier chord or turning it up louder.

You mentioned checking or cleaning "grounds", what are you looking for there?
 

teleking36

Member
Messages
3,954
cap job needed. once you get that taken care of, along with a routine service of the amp, you'll be good to go. i haven't stopped playing my '68 PR since i got it a few weeks ago.
 




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