SF Twin Reverb Vibrato Hum on Speed Pot??

[marcumh]

I've been hitting a dead end on this. Hopefully someone can point me in a direction. 73ish SF Twin Reverb has hum (120hz?). The hum goes away if I turn the vibrato speed knob to "10". The hum seems to be unaffected by any other pot movements. It is relatively low in volume and mostly unnoticeable when playing,....but I know it's there

[Enzo]

That link doesn;t work.

Go here:
Fender Amp Heaven Schematics - Tweed Blackface Brownface Silverface Bassman Champ Deluxe Princeton Super Vibroverb Reissue

Pick out the Twin Reverb drawing that matches your amp, and post a link to it. For example:
http://www.webphix.com/schematic%20h..._100_schem.pdf

[marcumh]

Schematic Retry

Oops,....this one should work. This is the MV (no push/pull) variant. Amp was BF'd at some point.