John, N9JG wrote:
Your advice is elegant in its simplicity.

And OPTIMISTIC in it's generality.
While one might imagine situations where this technique is
useful, it would be better to define a strategy that takes
into consideration the exact configuration of the PS in
your unspecified amplifier.

If your caps don't need reforming, any technique will work.
If they do, you're gonna have some current flow. It's not
hard to imagine a scenario whereby you have 25W or more
dissipated in your caps. I don't call this safe. A 100W
light bulb will keep you from blowing up the rectifiers while
you're blowing up the caps.

Assuming you have solid-state rectifiers, go back to the
variac and transformer. Depending on the value of the high voltage,
There may be issues if you just turn off the tube filaments.
The series lamp can still be helpful, but isn't the whole story.

It's always helpful to disclose the parameters of the situation
when asking for advice. Otherwise, you'll get 10 different
solutions based on 10 different assumptions, none of which will be
correct.
mike

"Andrew VK3BFA" wrote in message
oups.com...

wrote:

I want to reform the electrolytics in an amp I'm bringing back to life.
It runs high power, 220 volts ac only.

Can I use my 110 volt variac in conjunction with a 110V to 220V step-up
transformer to power up the amp? Obviously I'd not go key-down, but I
do want to ultimately get to the full B+ on the tubes.

How would I wire-up the variac / transformer, assuming it's possible?

Thanks in advance for the help, guys.

73,
Jeff
W8KZW

Its relatively simple and easy. Connect a 100w light globe in series
with the ac power input - this will limit current to a safe level. Run
for 10 hrs or so, will give caps a chance to reform....start with the
tubes in so the filament current draw limits cap voltage, then later
remove tubes to get virtually full voltage across caps....

Andrew VK3BFA.