fender reverb pot acting like drive pot?????

[texwest]

Hi Guys! Just got done recapping a vintage 65 princeton reverb. Turned it on for the first time and it sounds great except the reverb pot is acting like a drive knob when you turn it up.  It's like it creating more distortion as it goes up. Put it at about 3 and it sounds ok.  All the way down the amp sounds great.

Already tried different tubes in reverb driver and reverb return.

Any ideas what  is going wrong.  Thinking about replacing all the caps in the reverb circuit.  But wondering if it might be something like the reverb transformer.

I'm sure you can help me.   Thanks

[Latole]

Before working in the amp, how it sound ? Did the reverb pot is acting like a drive knob when you turn it up ?

[PRR]

Sure sounds like a new cap is bad or not really connected. Big reverb signal leaks through the RT into B+ and into a dry-signal stage.

[texwest]

Sure sounds like a new cap is bad or not really connected. Big reverb signal leaks through the RT into B+ and into a dry-signal stage.

I replaced the 22uf cathode caps on both the send and return tubes. Could it be one of those?

By RT do you mean return tube?

I was wondering about the .003 cap.  And the 470k is reading about 560k right now.  Definitely planning on changing that 470k.

I did not replace any of the signal caps.

[d95err]

I think PRR is referring to the powersupply filter caps.

[shooter]

signal leaks through the RT into B+

did not replace any of the signal caps.

[texwest]

I think I found the problem! This amp has always been wrong!!  Surprised no else caught it since 1965.

Fender put a 5000pf cap in the reverb feed instead of a 500pf.

Well that amp builder went dyslexic and thought .005 looked like 500. LOL

[Latole]

Congrat !

This answer to my question ( receive no answer ) september the 4th ;
"Before working in the amp, how it sound ? Did the reverb pot is acting like a drive knob when you turn it up ?"

[texwest]

Congrat !

This answer to my question ( receive no answer ) september the 4th ;
"Before working in the amp, how it sound ? Did the reverb pot is acting like a drive knob when you turn it up ?"

Latole,  I did not turn the amp on until I had replaced the filter caps, cathode caps and bias cap.  The owner reported very loud hum and terrible noises and I didn't want to turn it on and risk any damage without first replacing those electrolytics.

When I turned the amp on with the bias meters connected to both power tubes,  I immediately knew it needed new power tubes.  One meter spiked up to 100ma and the other did nothing at all and there was no sound, but terrible crackling and hum.  Replaced tubes and it worked great except the reverb.

On TDPRI they scolded me for taking this approach.  But even if I had turned it on just to see what happened, I still would have done the same thing.  I would have just turned it on and listened to it and immediately shut it down and never known about the reverb problem.

[Latole]

You have just to answer no.

I alway listen amps when receive in my shop and before work on.
It help to fix them with what I heard and with what owner said.

With the right fuse it is safe. Some vintage amp have a wrong fuse by last owners.
Never saw a amp damaged with old / bad filter caps. Amp just do hum.

[Latole]

Maybe the owner of the amp will not like the sound with the right capacitor ?
He will prefer the sound of the wrong "original "capacitor 0.005 ?

[shooter]

The owner reported

once I "understand the owner" I very seldom "jump" to power on, typically a really good visual, with magnifiers finds what the owner reports, even then I NEVER power up with PA tubes in before I verify bias volts on fixed bias.  then I typically put in my PA bench tubes to sacrifice, just in case.

[texwest]

You have just to answer no.

I alway listen amps when receive in my shop and before work on.
It help to fix them with what I heard and with what owner said.

With the right fuse it is safe. Some vintage amp have a wrong fuse by last owners.
Never saw a amp damaged with old / bad filter caps. Amp just do hum.

The owner reported

once I "understand the owner" I very seldom "jump" to power on, typically a really good visual, with magnifiers finds what the owner reports, even then I NEVER power up with PA tubes in before I verify bias volts on fixed bias.  then I typically put in my PA bench tubes to sacrifice, just in case.

Good advice Thanks!

[Latole]

My last asnwer is a very very short answer

Amp I don't know or I don't trust, I fired amp with bulb lamp limiter.
With Bias Probe on output tubes