silverface twin problems

[Chris Erbacher]

135 watt ultralinear version...haven't plugged it in in two years...sat in a van for all that time...tubes fire up look good...but it makes a nasty sounding groan like noise that doesn't sound like a 60 cycle hum sound...ground lift in the back does nothing to help it...reverb circuit doesn't seem to affect it...i'm not an amp tech but don't have the flow to make a trip downtown...what do i do, where do i look and what's goin on with this puppy? i have a soldering iron and basic skills so i'm hoping for a quick fix so to speak...any ideas? thanks in advance...

[Kevin Hatton]

You really need to take it to a qualified tube amp tech. You can kill yourself poking around in there.

[Tony Prior]

haven't plugged it in in two years...tubes fire up look good...

What Kevin said..

what do bad tubes look like ?

This could be as simple as a bad tube..but do not plug in that soldering iron and go poking around,you have in excess of 450DC in this puppy and unless you know what NOT to touch and poke you may be in for the shock of your life ! These are fine amps and very easy to bring back to life but please do not attempt a repair unless you are familiar and experienced.

t

[Jim Kennedy]

Two years in the back of a van would probably kill any amp. Extremes of temperature and humidity are not the friends of electronic equipment, not to mention the salt air in your area. IF it were me, the first thing I would do is take it apart and clean it really well. Look for corrosion on components, in tube sockets, on the chassis, everywhere. I once got a Peavey PA head that sat in an abandoned motor home for three years. It did some pretty strange things until I cleaned it up, especially the pots and the power transistors. As always, be aware of high voltages in the amp.

[David Mason]

I'm afraid I wouldn't even turn it on again, if you have to ask this question. A dead capacitor can equal a murdered amp, and if you knew how to tell, you would have? It's (potentially) close to a perfect steel amp, be a shame to... BZZZT!

Even besides dying, I mean.

[Dave Hopping]

Too cool of an amp not to bite the bullet and get it thoroughly gone over.

[Al Szwarc]

Since you aren't used to electronics, You can still look at it. Unplug the power cord. remove the amp from the cabinet. Look for mis shaped capacitors and the like. The main caps are under the metal box mounted to the chassis topside among the tubes. You may discover some parts or problems that are obvious. This may give you an idea of what is wrong. But the actual repair should be handled by an experienced tech. Plan B. Sell it as is for cheap and avoid the possible problems you may have. You will have some cash and some tech will have a good project. Al

[Kevin Hatton]

If you touch those caps before they are drained you will wish you hadn't. Not a responsible thing to go near them from a safety stand point without the experience to know what you are doing. Thats how bad things happen.

[Raybob Bowman]

Sitting in a van two years has probably corroded the tube pins/sockets. You can't hurt yourself by pulling tubes, and cleaning the pins with brass brush or 0000 steel wool. DON'T try to clean the sockets or you can see 450 volts in your hand holding the tool (with the amp unplugged).

When you put the tubes back in, you can run it with just power tubes and PI to see if the noise is there. Then add the preamp tubes. If the noise is back, pull one preamp tube at a time to see if the problem is there.

Also try unplugging the reverb tank. If you still have noise, take it to someone qualified to go in there.[/u]