RogerAF

Has anyone encountered this? My 50W head has been working fine, so I thought. I run all tones and presence at 10. Someone came to look at it and played with the tone controls. Bass and Mid seem to do nothing--no change in tone. When he tried turning down the treble the volume went away. We didn't really hear any change in tone, it acted like the volume pots. I don't know when this may have started. The amp has a real nice dirty sound, but the tone controls used to work.
Help Please!

starcitysongs

I'm not sure without playing around in the amp but in a Deluxe Reverb copy I built last year I had accidentally grounded one of the legs of the bass pot and it acted similarly. If it is circuit board based one of the solder joints on one of the legs could have gone cold and caused a similar effect. As stated elsewhere in the forum be sure to discharge filter caps before playing around in there though.

RogerAF

Thanks, I got the Treble control working again. I'm not sure what the exact problem was, but I pulled the PC Board up to get at the solder side and found several cold joints. I re-soldered all the connections that were questionable and everything began working again, except for the Presence. I checked all the values of all the components in the chain and they all checked out. The connections all have good continuity, but the control does absolutely nothing. I wonder if the tube it connects to may be faulty, but I have no tube tester anymore and since the tube passes signal, I don't want to screw around too much. If I had a spare tube, I'd try replacing it, but I don't, so I'm living without it. (I never set the tone or presence below 10 anyway.) The amp sounds great, so I'm not going to mess with it anymore.
Thanks for your reply,
Roger

mike sicowitz

Man there are some great old Gibson amps that are great exactly because the pots bleed into each other at high volume. The pricey new store down the block, Creamcity, has a 59 Gibson invader that I remember the trem boosting the volume like a preamp. I swear that amp got twice as loud when you turned the reverb and trem up to 10. That fault in design makes the amp worth over $1000, and my buddy is coming in from Cal just to see the thing. A grand is a lot to spend on a little old Gibson with bad wiring. But it's worth five times more than a skylark because pots other than volume add volume, I'm thinking it must be common.
Mike