1973 Twin Reverb Vibrato Issue

[plexi50]

I have a 1973 twin reverb. The reverb knob is interacting with the vibrato. The vibrato works fine.But when i increase the amount of reverb vibrato come full through the reverb foot switch and is loud! I have never seen this before.I have moved wires around and the board is severely warped.

[Latole]

Layout

[Latole]

Schematic

[plexi50]

Between both schematics they are using different resistor values.V3 Cathode is 470 ohm in one and 2700 in the other. So their are multiple schematics for this amp with the PP Master Volume?

[stratomaster]

Aged bypass caps can do some VERY weird stuff.  I had one even test as a diode on my little M-Tester unit.  Given the ground scheme in the area around the reverb send/return and foot switches--I'd be hesitant to judge the amp before making sure the caps are either healthy or replaced with healthy ones.

[plexi50]

Aged bypass caps can do some VERY weird stuff.  I had one even test as a diode on my little M-Tester unit.  Given the ground scheme in the area around the reverb send/return and foot switches--I'd be hesitant to judge the amp before making sure the caps are either healthy or replaced with healthy ones.

The amp has new PS Capacitors / Vibrato Caps / Bias Caps / Cathode Bypass Caps etc. New reverb tank arriving today. I just have never seen where a reverb pot has any effect on the vibrato. This is as weird as it gets.

[SEL49]

Is the footswitch an original Fender? Try a different real Fender type footswitch.

[stratomaster]

Aged bypass caps can do some VERY weird stuff.  I had one even test as a diode on my little M-Tester unit.  Given the ground scheme in the area around the reverb send/return and foot switches--I'd be hesitant to judge the amp before making sure the caps are either healthy or replaced with healthy ones.

The amp has new PS Capacitors / Vibrato Caps / Bias Caps / Cathode Bypass Caps etc. New reverb tank arriving today. I just have never seen where a reverb pot has any effect on the vibrato. This is as weird as it gets.

Those white Mallory caps terminating at the RCA jacks in your photo are electrolytic cathode bypass caps.  These are specifically the ones I'm talking about.

Your photos show the board mounted bypass caps have been changed, but these remain. Did you replace them after you took the photo?

[plexi50]

Aged bypass caps can do some VERY weird stuff.  I had one even test as a diode on my little M-Tester unit.  Given the ground scheme in the area around the reverb send/return and foot switches--I'd be hesitant to judge the amp before making sure the caps are either healthy or replaced with healthy ones.

The amp has new PS Capacitors / Vibrato Caps / Bias Caps / Cathode Bypass Caps etc. New reverb tank arriving today. I just have never seen where a reverb pot has any effect on the vibrato. This is as weird as it gets.

Those white Mallory caps terminating at the RCA jacks in your photo are electrolytic cathode bypass caps.  These are specifically the ones I'm talking about.

Your photos show the board mounted bypass caps have been changed, but these remain. Did you replace them after you took the photo?

You were right on the cathode bypass caps on the RCA jacks. Changed them out and Presto! No more chirping with the reverb pot. You learn something new everyday no matter how long you have been doing anything in life daily. It's just i overlooked them and expected it being something much worse. Confession Day! Thanks much for all your help! Im 68 now and my mind is slipping more everyday. It Suks.

[Willabe]

Nice catch stratomaster. 

[plexi50]

Nice catch stratomaster. 

This board has little wax on it and looks like a roller coaster in the middle.