#1
I really hope my title kinda sums up the problem.

The amp is an 1972 Ampeg VT-22.

For the past couple jam nights, everyone's noticed a nasty electronic smell which we attributed to the new cheapo Behringer speakers we just got. Last night the smell got horrendously bad, my buddy shut the PA speakers off for a while because we all thought it was that. My amp has given off a bit of a scent ever since I've bought it around 10 months ago, but never this bad.

The volume started fading so I turned the amp on and off and it would recharge almost like it was a capacitor issue and then it just faded to a very low volume, distorted and shrill tone.
The tubes are either NOS or the original Magnavox and Westinghouse tubes. Caps seem original, but then again it could be a replacement. The guy I bought it from said it was his dads.
I tried using the polarity switch and whatnot, I'm running the unit through a power conditioner. The amp itself is ungrounded, something I've been meaning to fix.

So I took the head out of the combo, flipped it over on the bench and found out the output transformer(I'm assuming this because it's the larger one) was extremely hot, almost to the point where it hurt to touch. The smell was emanating directly from it.

So the first thing I suspect is my cabinet and a mismatched load. Turns out my cabinet was reading at 22 ohms on the multimetre, so I take the speaker grill off, and begin testing impedances. Blown speaker.

I guess overall what I'm wondering is, do you think it'd be safe to try out on another cab?
I'm thinking maybe if I turn it on again I might lose my chance at somehow saving the transformer, so I'm worried in that reguard.

Thanks for your time.
..I was watching my death.
#2
I don't see any reason not to try it. If the transformer isn't fried, you're not going to damage it further by testing it, and if it is fried of course it's too late. There's not really a scenario where you can "savie" the transformer anyway. A 'fix' is a complete re-wind, in which case you might as well just buy a different one. So, go for it. Nothing to lose.
#3
Quote by Roc8995
I don't see any reason not to try it. If the transformer isn't fried, you're not going to damage it further by testing it, and if it is fried of course it's too late. There's not really a scenario where you can "savie" the transformer anyway. A 'fix' is a complete re-wind, in which case you might as well just buy a different one. So, go for it. Nothing to lose.

Alright well that's good and bad to hear, thanks.

I'm having extreme difficulties getting speakers here, does anyone know a good Canadian retailer? There's only two speakers available locally, a Mesa Boogie Celestion V30 for 189 or there's a Garnet speaker for sale for 60 on the classifieds.
..I was watching my death.
#4
There's Long and McQuade, Guitar Centre at some Best Buys, and Strings and Things for retailers.

I had a similar problem with a guitar amp. It was smelling weird, then it just straight up stop working. The speaker was blown and the transformer was fried. I never found out why, the impedance was matched. Could be that you're pushing the amp too hard. Are you pushing it for volume?
#5
Have the transformer checked. The larger transformer is the power transformer, smaller one is output.

Can't tell you a thing about speakers in Canada...

Replace every capacitor in it before you use it any more, If you're lucky it hasn't already fried a transformer. Capacitors dry out after 25 to 30 years, or the electrolyte inside them actually. If one develops a direct short it can fry a transformer. That's what was wrong with my 73 Fender Super Reverb when I got it, one of the "orange drop" capacitors, as they are called, was bad and it did just what you described. After about 10 minutes the volume would drop as if you pulled a power tube, fizzy and distorted sounding, not good...I thought it was a bad output transformer, and while I waited for a good paying job ( trim carpenter) I started replacing capacitors, I knew they were over 30 years old and needed to be replaced. The last orange drop I replaced did the trick, it still works perfect today. I think those are called polypropylene capacitors.

Replace every electrolytic cap in it. Those are the ones that look like small oil cans. The polypropylene should probably be replaced too, most companies used the cheapest stuff they could fond, the 70's Fenders were known to be made with cheap blue or brown ones. The ceramic disk type usually lasts a long time, probably no need to worry about those.

If you work on it yourself, be very careful. The large electrolytics, filter caps, hold a high voltage charge for several months after being unplugged and shut down. It is literally deadly inside a tube amp...You'll need to use a well insulated jumper cable with a high wattage 2K resistor to drain them. Most tube amps use 350 to 500 volts. I think my Super Reverb has around 380V in some places, the Champ about 320 or so. Not healthy...

http://www.learningaboutelectronics.com/Articles/Types-of-capacitors
Hmmm...I wonder what this button does...
Last edited by Paleo Pete at Jan 24, 2016,