Pro Tube reverb buzz

[Jmast6662]

HI all,
I have a Fender Pro Tube/Pro Reverb 1x12 combo.
Problem.

When ever I turn on the reverb using the foot pedal , its quiet when reverb off,I get a buzz which increases and decreases when I turn the Reverb Vol up and down. If I unplug the footswitch the buzz is also there.

I've isolated the problem to the reverb circuit and have changed out all the valves to see if its a valve problem but no change.

Opening the chassis R69, the grid resistor to V5, was microphonic when tapped, changed this out but still making a noise when tapped and buzz still there.

Any ideas?

[Blindog]

Welcome to the Garage!

Try checking the cables from the reverb tank to the chassis. I seem to remember a similar problem I had with a Super Reverb, and it was cable related...at least for my situation anyway

Good luck!

Mark

[xtian]

OP said buzz is still there if ftsw is unplugged.

Has the reverb EVER performed as you want? I mean, is this a new issue?

[Blindog]

OP said buzz is still there if ftsw is unplugged.

Has the reverb EVER performed as you want? I mean, is this a new issue?

Right on xtian, my issue was with the braided RCA send/return cables on my amp...If I recall, one of the the outside shields had become hot! It didn't matter if the verb switch was engaged or not...definitely weird!

Mark

[JazzGuitarGimp]

Try removing the reverb tank from the cabinet, and move the tank around while listening. If you have the "return end" of the tank near the PT, it will induce hum into the reverb pickup coil.

[Jmast6662]

Thanks for the thoughts Guy, its not my amp but a friends who says this is a new issue. I'll try with new RCA cables and see what happens. I'll let you know.

Cheers