I have a 1976 silver face Princeton Reverb on the bench. Cap job, new power string resistors, updated bias circuit with adjustment. Got it working and sounding quite good. Played it a few days, no issues. Was just waiting on new power tubes.
New JJ 6V6GTs arrived, put them in, set bias, zipped it back up...very low sound, distorted output. Pulled it back out, three hours of troubleshooting later, can't figure out what's wrong.
Trouble seems to be in cathodyne PI. I should have ~200v on plate, ~50v at cathode. Instead, I've got about 110v on plate, cathode and grid. Tried new tubes, resoldered all connections, measured component values. All other voltages near spec.
Stuck.
1976 Fender Princeton Reverb trouble
Moderators: pompeiisneaks, Colossal
1976 Fender Princeton Reverb trouble
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I build and repair tube amps. http://amps.monkeymatic.com
Re: 1976 Fender Princeton Reverb trouble
Never f-ing mind. I put in a THIRD PI tube, and this one works fine.
I build and repair tube amps. http://amps.monkeymatic.com
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Stevem
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Re: 1976 Fender Princeton Reverb trouble
You'll get a better clipping tone out of it if those big ass .1 coupling caps are dropped back to .47 if the low end stays fat enough for the owner when played at low volume, better dynamic range too!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 1976 Fender Princeton Reverb trouble
True, Steve. But I wasn't hired to make mods!
I build and repair tube amps. http://amps.monkeymatic.com
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Stevem
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Re: 1976 Fender Princeton Reverb trouble
I hear Ya!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 1976 Fender Princeton Reverb trouble
I was impressed by this amp. It was the quietest at idle I've ever heard from a Princeton, and the reverb was exceptionally hum free. It had a cheap, no-brand AlNiCo 10" in it, which sounded crappy when dimed, but thru an external cabinet it was very good when cranked. I measured about 10 watts clean power.
I build and repair tube amps. http://amps.monkeymatic.com
Re: 1976 Fender Princeton Reverb trouble
I gotta say, Princetons have great tone. I dare say I prefer them to the Deluxe Reverb.
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
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Re: 1976 Fender Princeton Reverb trouble
I gotta kind of agree on that, I like the way that PI is never 100% clean!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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dorrisant
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Re: 1976 Fender Princeton Reverb trouble
I see I'm not the only one to get stuck on stupid sometimes... No slight to you Xtian, I go there myself too. Makes us feel human. Glad you got it fixed!
Tony
Tony
"Education is what you're left with after you have forgotten what you have learned" - Enzo
Re: 1976 Fender Princeton Reverb trouble
Did u mean .047?Stevem wrote:You'll get a better clipping tone out of it if those big ass .1 coupling caps are dropped back to .47 if the low end stays fat enough for the owner when played at low volume, better dynamic range too!
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 1976 Fender Princeton Reverb trouble
Yes, I left out that zero, sorry!
Some folks even like a .022 in there and it's a good thing to fool around with if you play the amp opened up past 5.
Some folks even like a .022 in there and it's a good thing to fool around with if you play the amp opened up past 5.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!