69 Ampeg gv22 ch1 not working

[the#9]

Hi,
I've recently acquired a 69 Gemini GV22. Excellent clean sounding amp. I've sprayed all the pots ,switches, and tube sockets also dressed the tube posts with 400 sandpaper. But only ch 2 is working. The amp is dead quiet no pops, hissing etc. even after being on for a couple of hours.
When pushing it at above 6 or 7in volume, I did notice some distortion at hard attack moments. Otherwise very clean and good sounding amp.
Problem is Channel 1 is completely dead as if not even hooked up. You turn the volume up and hear nothing- no hum or hiss etc.
I would love to get this up and running again to hear that nice vibrato and reverb.
The original tank and foot switch are ,both look good too.

Any help to know where to start would be very helpful.
Thanks,

[Hangman]

Hey the#9, welcome to the VintageAmpeg.com forums!

The GV-22 is an awesome amp. I like to think of it as the big brother to the gemini-1 which is my favorite amp. I was surprised the first time I played one because I wasn't expecting it to be as clean as it was. The G12 tends to break up a little more. I still drool over ever GV-22 I see them at guitar shops. I do have the guts from one that went through a fire. maybe some day I"ll piece one tougher.

anyway... have you tried simply swapping the preamp tube for channel 1? it would be the fifth tube from the left, when looking at the amp from behind. i.e. the first tube would be a 6L6, second another 6L6 then a 7199, followed by a 12ax7 (for channel 2) and the fifth tube would be the 12ax7 for channel 1.

[jjmt]

Just to build on what Hangman has already mentioned, dead silence usually means something has died. You either have a dead tube, or an open resistor (probably a plate resistor, or a shorted resistor (particularly one that goes to ground). The thing is, looking at the schematic, there are no fewer than 3 preamp tubes in channel 1, so it is going to take some debugging. The first question is: do all the tubes light up? Fixing a dead tube is by far the easiest thing to do.