Fender Twin hum

[Chris Haston]

I just bought a used RI Twin Reverb a few days ago. It has worked fine until tonight. When I got home from work, I turned it on, and there was a deep hum. I figured out that it was the reverb. If I turn the reverb all the way down, it's not easily audible, but it's still there. I don't know much about these amps, so I don't know if this is a common problem, or what I should do. It has worked great for the last few days. I should also note that I made sure all of the tubes were well connected. Help anyone?

[John Daugherty]

Chris, we need to know if there was anything plugged into the input and was the input gain control at minimum or was it turned up.
Disconnect anything plugged into the input to eliminate that.
It has been mentioned many times here, to clean the plug that connects the reverb unit to the amp (apply contact cleaner and push plug in and out several times).
Check these first and get back to us. Good luck..........JD<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by John Daugherty on 02 January 2005 at 04:19 AM.]</p></FONT>

[Chris Haston]

Thanks John. I did what you said. Unplugged the connectors on the reverb, and it solved my problem. Thanks for the quick response
Chris

[Mark Herrick]

On older Twins (I have a '74 Silverface) and some other models (my '90's "Custom" Vibrasonic) there is a "hum adjustment" pot in addition to the bias adjustment (or balance) pot. You might check to see if your amp has this feature; seems like it should.

To adjust for minimum hum, you need an open plug (a 1/4" plug with nothing attached to it) in jack position 3 (first input in the second channel) with the second channel volume, mid and bass controls on 10, reverb and vibrato off and all channel one controls off. Then adjust the hum pot for minimum hum.

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<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Mark Herrick on 02 January 2005 at 03:12 PM.]</p></FONT>