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Vintage tube amp resurrection with Variac?

I have acquired some vintage tube equipment that has not been turned on for several decades. I bought a Variac on eBay having read many times to be sure to "bring up" old tube gear "slowly on a Variac". What exactly constitutes "bring up slowly"? Is it some sort of staging perhaps? If so, what voltage at each stage, number of stages, how long per stage. Or does it mean to continuously, but very slowly, crank the Variac from 0 to 117 volts?
elunkenheimer

Showing 3 responses by dekay

dekay's avatar
dekay
5,349 posts
 
If using a variac on a unit with the tubes installed care needs to be taken if the item is tube rectified.

If it has a slow start rectifier installed it will NOT see a slow ramp up from the variac, but will eventually quickly see higher voltage, which is not good for reforming caps.

There are some quick start subs for a GZ34 (think I once used a 5Y3, but not certain as it's been awhile).

A local tech once used a SS (plug in) rectifier on one of my vintage amps with a GZ34 (he made made it in a manner of minutes), but I've seen them for sale online as well.
dekay's avatar
dekay
5,349 posts
 
Czarivey:

Your advice does nor gell with the tech that worked on my Pilot 232, nor the advice I received from the AA forums.

Basically I was told that a GZ34 will not start to pass current until it reaches 80-90 VAC (which is 4-5 times higher than one wants to start when reforming lytics).
dekay's avatar
dekay
5,349 posts
 
Czarivey:

Also forgot to mention that if using a 5Y3 (in place of a GZ34) it needs to be replaced with the proper tube once you get up to higher voltages (very important point left out).

Sorry, didn't notice the DC cap info.

I once used the light bulb method (think it was on a Pilot 240) and it worked well.
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