Early Gibson GA 40 Foot Switch Wiring

[plexi50]

I have a mess of a 1952-4 Gibson GA 40 amplifier that i am attempting to get up and up and running again. So far i am just tacking in new Xicon replacement caps before using Sozo Capacitors. It is a mess. But i have the Microphone channel running but squeeky.I have no Instruments channel so far. I have traced and pulled my hair out for 1 month so far. I am using the attached schematic. This thing makes no sense in a way. A real odd ball. The tremelo functions with the speed rate. But i can not turn it off so far. I am partially going by the parts that are in place when i got it and replacing them one by one now that i found this schematic.
The foot switch leads are wired to the Tremelo 6V6GT tube pin 8 & 6SN7 pin 8 as i found them. I'm thinking that's wrong and should be a grounded connection.   

[sluckey]

Wish I could see that schematic.

[sluckey]

6SN7 pin 8 is a filament connection.

[plexi50]

GA 40 Pic's

[plexi50]

Pic's

[plexi50]

I removed tremelo switch wire from 6SN7 Filament as i found it and grounded it. THE SWITCH IS WORKING NOW. I get instrument channels to work if i press my hand on the tremelo switch wire. WTF?

[rafe]

I'm almost ready to adress the tremolo in my 53 ga-40 (Les Paul) I recapped it and changed out the out of spec. resistors , bu never adressed the tremolo. It looks like the switch is between the cathodes of the power tubes and the cathode of the 6v6 tremolo .....I am just a little gunshy on doing that .....I see no evidence of where they cut the footswitch out ......Great sounding amp for sure

[rafe]

will this work for footswitch?

[sluckey]

Yes. But notice that R30 (1K) is connected directly across the switch. IOW, the cathode of V7 connects directly to the cathodes of V5 and V6 through the switch or through R30 when the switch is open.

[plexi50]

The foot switch acts like it should be in a shielded cable type wire. The instruments channel will only work when i press my hand on the foot switch wires. This is beyond weird. Remove the foot switch all together and no instruments channel at all. I have been all over V2 and through the PI 6SN7 and it is wired correctly. At this point i dont care anymore if i get it working or not.It's just the calling to find the problem that's got me  This ain't rocket science!

[rafe]

Plexi, I don't know if you have this one too....I may have another I'll check .....I am having a similar brain- F^(K With a Ga5 that was working fine but had some out of spec resistors that I changed and bow I've been at it way too long and can't solve it ....I know it's right in front of me .....BUT....

[rafe]

The lay-out is useless unless seen or printed in color..

[tubemaster]

Just a note that the GA-40 Layout drawing shows the the cathode bypass capacitors for V1 and V2 reversed. The positives of the caps should be connected to the cathodes of the 6SJ7's.

[rafe]

Amp is still working fine, never did hook up tremolo. It's got to go back on the bench for socket rubbers at some point.......My next big project is the GA-50T (1952) it gathering dust in my amp crypt room....

[Platefire]

I had a 1961 GA-40 Les Paul Amp. Never did get the trem working. I always wondered what the trem sounded like as compared to Fenders I was familiar with. I did have the
original wooden footswitch.

The rest of the amp worked fine. Gave it to my Son.