How to restart tube amp and pre in boxes for 2yrs

Running a tube amp for any length of time without output tubes installed, as Hifigeek suggests, can be very dangerous. The reduced current draw in the power supply will cause the B+ voltage to shoot up considerably, and may exceed the capacitor maximum voltage rating. On an older amp with marginal capacitors, this greatly increases the risk of capacitor failure. The Variac idea is a good one, but leave the tubes in place, or monitor the voltage on the capacitors to make sure it stays below their rated voltage.

Indeed Selectric, I even monitor AC ripple as I'm bringing the voltage up and carefully touch the caps to make sure they're not heating up!

Hifigeek1,

You are far braver than anyone I know when charging up questionable caps. A friend had a cap blow up when he turned on an old amp and he said the explosion was unbelievably powerful. He is a gun person so he knows what loud is, and he said the cap going up was louder than any gun he has fired.

Larryi I've been doing that kind of work for 25 yrs. Actually a cap will give you warning signs. At low voltage they can heat up and/or sizzle or tic from arcing. That's why you run the amp up slowly. Never bring an amp with caps that make noises up to full voltage. Also if the cap is leaking from the vent.

I'm too much of a chicken to be close by looking for warning signs. I lend my stuff to a friend who can power it up on a variac for me.