I've got voltage on the chassis

[C Moore]

OK -
I have 35VAC on the chassis of a 1968 Twin Reverb. It belongs to a friend of mine. She has had it for quite a long time, but never really played it. After i got into I found it had been heavily modified. There was a MV added (of all things), the vibrato channel was used for an extra gain stage of some kind, and there were a lot of component value changes, caps in parallel, etc. etc..
Anyway... I git rid of all that and returned it all to BF specs, including the bias circuit, did a cap job, etc.
Everything seemed to work OK, the bias adjusted fine, but the chassis is hot in reference to ground. Do you guys have any idea where I should start looking?
Thank You
I installed a 3 prong cord. I wired it o the existing 2 position ground switch. Hot and neutral to the g switch. From there the hot goes to center fuse, top fuse to tranny. Neutral goes to stand by. Ground to one of the screws that hold tranny to chassis.

[Wayne]

If you're still using a 2 prong plug for power, check your "death cap".

Even better, switch to a grounded power cord.

W

[M E 5000]

Maybe i'm missing something, but didn't he just say that he installed a three prong cord with the ground?

[Jana]

I installed a 3 prong cord. I wired it o the existing 2 position ground switch. Hot and neutral to the g switch. From there the hot goes to center fuse, top fuse to tranny. Neutral goes to stand by. Ground to one of the screws that hold tranny to chassis.

Neutral going to standby?

I would not use the ground switch at all.

Hot from power cord>center of fuse > side of fuse > power switch > other side of power switch > tranny.

Neutral from power cord > other leg of tranny.

ground from power cord > chassis.

Nothing connected to ground switch = longer lifespan.

[jaysg]

Neutral (wht) does not go to any switch, unless it's a 220/240 unit with a dual pole On/Off switch. Run Hot to the fuse first, then to the power switch.

[Wayne]

Maybe i'm missing something, but didn't he just say that he installed a three prong cord with the ground?

Ooops! Missed that first time through. Will try not to shoot from the hip next time.

That being said - with the ground switch still being in play, the death cap is still suspect. I'd be interested to know if excluding it cures your problem.

W

[Phil_S]

Clip the death cap. Wire it like the picture says. Unsure of that switch, but you need it to work as if it is off-on and nothing else.

[C Moore]

Maybe i'm missing something, but didn't he just say that he installed a three prong cord with the ground?

Ooops! Missed that first time through. Will try not to shoot from the hip next time.

That being said - with the ground switch still being in play, the death cap is still suspect. I'd be interested to know if excluding it cures your problem.

W

First of all, my apologies to you Wayne. I edited my post after you asked about a 3 prong cord. And yes, the death cap has been removed.

I will take a look at the schematic that has been posted concerning my ground switch situation.

With that said, I no longer have any VAC on the chassis. After looking at the layout again I found that pin#7 of the reverb tube was not connected. That is now as it should be and this amp sounds fine. Don't know where I was getting that AC on the chassis from. But after chop sticking a bit, and correcting my reverb mistake, the AC problem is gone. I am happy about that, but I wish I knew exactly what happened. Oh Well!!
Thank You Everybody

[Alexo]

Just to be safe, were I you, I might get one of those little plug-in units from the hardware store that lights up if your outlet is wired incorrectly.

[mlp-mx6]

Just to be safe, were I you, I might get one of those little plug-in units from the hardware store that lights up if your outlet is wired incorrectly.

Excellent suggestion.

[Structo]

Also don't these amps circuit boards frequently go conductive?
The fish paper boards?

[jaysg]

Also don't these amps circuit boards frequently go conductive? The fish paper boards?

Not sure about frequently, but yeah. I've never been clear on just what the Fender material is and just what exactly fish paper is, except I think they're different. QSC uses fish paper in their power amps, so it must have its place.