How to safely power up a tube amp unused for years?

[stobro]

In addition to the way-too-many guitars I have laying around, I have five tube guitar amps. Only one has been powered up on a regular basis. The other four have been silent for over five years. What's the best way to power them up safely? I don't have a variac. Should I look for an amp tech with the proper credentials and equipment? For the record, the amps are a Trace Elliot Velocette SE (single ended), a Fender "30" from around 1980, a 1963 Fender Tremolux and a 1948-ish National/Valco amp (field coil speaker, octal preamp tubes).

[Jakeboy]

The only safe way and responsible way to fire up that Tremolux is TO SEND IT TO ME! I have always wanted to play a Blonde Trem.

If the amps were played 5 years ago and they played fine then, they will likely be fine....but 3 of the 4 are old. When were the filter caps last replaced?  If they are old I’d have a tech with a variac  bring them up slowly and give them the once over.

The Trace Elliott is the exception. It will likely be fine as it is a newer amp, right?

[Dutchman]

Find a tech and have all the caps inspected and tested before any juice to it. Replace any bad ones!! Have the tech Bring it up with a variac and watch the current draw. If there’s a lot of amps stop and look for shorts and burnt resistors. If you want it to look original hollow out the old caps and stick the new ones inside the old shells. A good tech know’s all this stuff!!

 

[stobro]

I'm pretty sure none of them have ever had their filter caps replaced- even the 72 year old Valco. I'm assuming the shiny aluminum cans are the main filter caps, correct? The last time I powered it up 5 or 6 years ago it worked fine. There are a few of what appear to be newer coupling caps inside, but the Mallory Type FP caps appear to be original.

[stobro]

I opened up the Tremolux to find that the filter caps have been changed- at least they look newer than the rest of the components.

[Jakeboy]

That Tremolux looks beautiful. The safe thing to do is to have a tech slowly bring them up on a variac.

[killerteddybear]

If capacitors are the issue, then wouldn't this advice (variac startup) apply to solid state amps as well?

Certainly lower operating voltages but dead caps are dead caps.

[stobro]

I decided to throw caution to the wind and fire up the Velocette SE. Initially there was a little more hum than what I would think is reasonable for such a low-power amp. Then it started howling, rather quiet, around an E flat over middle C. Guitar volume up, down, plugged in, unplugged, amp volume down made no difference. Now I remember why I haven't played through it in five years. It may be a bad tube somewhere. I did a lot of experimenting with different tubes as the SE version of the Velocette is made for tube experimentation. Many of the tubes were old stock, and there may be one or more bad ones in it. I need to get some that have been tested good. If known good tubes don't fix the problem, I'll take it to a tech.

[Jakeboy]

Def sounds like a bad tube....what tubes are in there? I may be able to hook you up....

[stobro]

I swapped out the vintage tubes I had in there for the tubes that the amp shipped with and that fixed the problem. So at least one of the vintage tubes is bad. Many years ago I got tubes from various sources to experiment with. I don't have any way to test them, or in the case of output tubes, to match them. I need to find someone who can go through all of them and cull out the duds from the keepers.

I called a local music store that has a service department and left a message asking about diagnosing my amps, and no one ever called back.