Twin reverb quiet

[pops]

I had a silverfaced twin come in that has had many mods, some good some not. Blackfaced, master disconnected, bias rebuilt to a true bias not the balanced. Anyway it was very quiet. While checking voltages and everything looking normal i touched the grid of the reverb channel preamp tube coming from the volume control and it came to life. I then noticed the grid wire was touching the cathode wire, enough to make a mark where it rubbed, i separated these two wires and it has been playing music with nice volume since. My question is, was the fact that these two wires touching even tho insulated causing the volume drop or was it something else that is now working? Thanks

[gui_tarzan]

My guess is there was probably a tiny hole worn through the insulation from rubbing together causing them to short. It doesn't seem like the grid voltage would be high enough to arc through but...

[Stevem]

I would make a more likely wager that the tube socket and or the pins need a good cleaning and then I would hit the tube pins with some Deoxit D100 on a Q tip swab.
Rock that tube around real good and make sure it's solid with no noise!

[pops]

Thanks for the replies. I rocked the tubes before it came back on and it was still quiet. No insulation gone, but a black spot on the white wire from the inside of the shielded grid wire. Played music thru it for 2-3 hours today and worked fine. Still wondering what it really was.

[Stevem]

Sounds like its fixed then Bro!

[DonMoose]

Thanks for the replies. I rocked the tubes before it came back on and it was still quiet. No insulation gone, but a black spot on the white wire from the inside of the shielded grid wire. Played music thru it for 2-3 hours today and worked fine. Still wondering what it really was.

A black spot in a spot where no black wire could touch sure sounds like an arc of some sort. I expect two insulation faults just happened to line up under 'favorable' conditions, and there was enough carbon between the two wires for the return signal to get swamped.

[Stevem]

Well pin 7 the grid is right next to pin 6 the plate, lucky that was not a pin 2 to pin 1 short on V1A when a guitar was plugged in, that will make your fingers move fast with no blocking cap in the circuit !

[gui_tarzan]

Given there is a black spot on the wire I'm still going with an arcing from one wire to something else. It doesn't take much.

[pops]

One wire is black the other is white, the owner plays LOUD so i'm thinking it was rubbing and caused the mark, but also caused the problem, since i am not finding anything else and is working now.