Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tsquared on November 04, 2010, 11:06:31 am

Title: outside foil on unmarked PIO caps?
Post by: Tsquared on November 04, 2010, 11:06:31 am

I scored a giant bag of NOS Pyramid paper in oil caps from a serious hoarder's estate sale.

They aren't marked as to the outer foil like a lot of older caps.  I read that if you hold the caps so you can read the writing on the cap, the outer foil should be on the right end of the cap... but I'm still not 100% sure this is accurate. Is this true for the Pyramids?

I did see a cool jig for testing for the outer foil connection on Youtube using just the input to a guitar amp, a toggle switch and a couple alligator clips.

Any help would be appreciated.

Tod

Title: Re: outside foil on unmarked PIO caps?
Post by: FYL on November 04, 2010, 11:39:49 am

A large number of these old caps are leaky and thus unusable. They should be fully bench tested before any amp use.

Re. their orientation, check http://www.aikenamps.com/OutsideFoil.htm

Title: Re: outside foil on unmarked PIO caps?
Post by: Shrapnel on November 05, 2010, 04:21:07 am

Gabriel had an easy tester any of us could build that can plug into just about any working amp.

Here's the youtube link to the device: http://www.youtube.com/watch?v=VP6ZIHXq6Yg (http://www.youtube.com/watch?v=VP6ZIHXq6Yg)

Here's the article on it on one of his sites. http://www.soundgaragetales.com/amp-building/outside-foil-capacitor (http://www.soundgaragetales.com/amp-building/outside-foil-capacitor)