Fender 6G14A Concert tremolo stops working at maximum settings

[booj]

the beautiful warble is there at lower settings. The speaker really moves a lot while it is modulated and there is an undertone whump whump sound besides the guitar signal that is very noticeable at higher intensity settings. At maximum intensity, the trem just stops working altogether at the highest speed setting, even if I bring the speed up gradually. Right at max, it dies. This is THE Fender trem circuit using 21/2 12AX7's. I've got to get this working right just to hear it!
Concert Amp 6G12-A K-FJ Schematic.pdf

[Jazz P Bass]

At the point where the Trem stops working, run a continuity check across the pot, from the .002 cap end to the wiper.
I'll bet it's going open.

[booj]

Nope JPB. Not going open. Guess I'll start by changing the caps in that area.

[Justin Thomas]

I'll assume you tried new tubes & checked voltages, resistors, etc? I've got one that wworks just fine if you want me to compare any measurements voltages... I know schematics can have errors on them, too. Only thing with mine is that someone did a "cap job" and replaced ALL the caps! The amp saw water damage at some point, but I find it hard to believe none of the carbon comp resistors went bad too.

Hope you get it fixed; it IS worth it!

Justin

[Chuck H]

Maybe check the .1 cap to ground from the max setting end of the intensity pot. It may be leaking or shorted.

[booj]

Fixed it. The excessive whump whump sound was caused by me replacing the 4.7uf cathode cap with a 25 uf. in the mixer section. The 12AX7 was bad in the V3 oscillator position. Looked to be a brand new looking NOS GE too. Thanks much for your help! It prevented me from replacing massive amounts of caps. This thing looks brand new inside. The sound is indeed gorgeous.

[Jazz P Bass]

And you gotta wonder how we where supposed to know That.

Glad you got er.