CAPACITOR QUESTION

[TWRECKS]

Hello everyone,
I just want to start off by thanking everyone who contribute to this forum regularly. I have only been here for a couple of weeks. Reading some of the older posts has helped me to get past some of the road blocks associated with my first WRECK style amp. I have learned a lot from all of you, so THANKS!

I am new to tube amp building, however, I have been working on my amps for a while now.

My question: Is it possible to form new caps using the light bulb in series with an extension cord? Does this work as a solid alternative to a variac?
Using this method how long does it take before new caps are properly formed and the amp is ready to play?

Thanks,
Anthony

[geoffreysnow]

new caps don't have to be formed.

[mhuss]

+1 -- do you think Fender or Marshall have a long of variacs to soft start every amp that rolls off their assembly lines?

--mark

[Jimy]

The "re-forming" of electrolytic capacitors is something that's really only necessary when you're working with old electronics that haven't been used in years. When electrolytic caps sit idle for long periods of time, the dialectric (a microscopic layer of metal oxide) actually breaks down and disolves. As a result, the cap can fail (sometimes explosively) when full voltage is applied... wreaking havoc on the rest of your circuit. By applying the proper voltage through a resistance for the proper amount of time, you can re-form the cap and bring it back to a functional state. It's kind of an old-timer's trick from the ham radio guys. You don't see it much amongst guitar amp techs unless somebody finds a "closet classic" '59 Bassman that grandpa bought brand new and never used... you wanna fire it up and see if it works? ...ka-bam! ...hmm, shoulda used a Variac...

Bottom line, like everyone said, new caps are already formed and ready to go. Unless you're buying your caps Army surplus, you don't need to do anything.

[TWRECKS]

Thanks for the help everyone. I had read at one time where the new caps should be properly formed after installing them into the amp. I thought this was the way to go. Guess you can't believe everything you read. Amp Building is a relatively new to me. I can follow a schematic and put it together but I'm still learning the Why this works aspect.

Thanks Again,
Anthony