reforming caps

[charles w. morehouse]

Right on George, do the same with the Heathkit IT-11. Most useful tool
in the shop. 73.
Wayne;
W4GBW

George Maier wrote:
>
> Ken:
> Your'e on the right track with the Sprague. I have used a TO-6 here for the last ten
> years, and have developed some proceedures that work for me.  If you are going to check an
> old electrolytic, it's really wise to re-form it first.  I usually start with a very low
> voltage; if it's a 450V cap, I'll start at 50V, and wathc the leakage current.  Most of
> the time it settles down to microamps.  Every time this happens, I raise the voltage by
> 30V or so, until I get to the full value, or at least to the voltage that it will be
> operated at. Each time, you have to wait until the leakge current drops.  It works in
> about 80% of the cases.  Some are just beyond reforming.
> Once it's reformed, wait until the cap has completelty discharged, then do the value and
> power factor check.
> Vy 73
> George Maier - K1GXT
>
> Ken Ketner wrote:
>
> > Bruce and others:
> >
> > Thanks for info about reforming caps. I have been able to find axial
> > caps of new manufacture of any voltage up to 450 wvdc through antique
> > electronic supply (I have no interest in the company) in Tempe AZ for a
> > buck or 2.
> >         I have a Sprague cap analyzer in my shop which has an eye tube and a
> > bridge for determining value, a voltmeter and an ammeter built in, as
> > well a provision for putting up to 600 volts (variable) onto a cap. One
> > can watch the meter and see what the leakage current is. When I clip a
> > lead on an el cap and slap the Sprague on it, I find that no matter how
> > long I keep the voltage on most old caps, they still will come down to
> > leak around 3-10 milliamps, which is too much it seems to me. A cap will
> > settle down after 3 or 4 minutes on voltage, but almost never at an
> > acceptable leakage value. SO I have always thought that clipping in a
> > recently manufactured one from Antique el sp is the way to go. That
> > means I won’t have top be back in that particular chassis for some time.
> > I also routinely clip in interstage caps for the same reason. Am I
> > missing some part of the forming procedure? Does one have to leave them
> > on voltage for a week or a day or something?
> >         On can caps, Antique offeres new manufacture on those too, but they are
> > 20-30 dollars. So I get a tie strip, fix it to a bare spot on the
> > chassis, and using new axial lead caps, rewire the can leads. Same
> > effect for half or third of the money. And if one wants the can to stay
> > there for esthetic reasons, that is fine.
> >         We inquiring minds want to know
> >
> > Many thanks
> > --
> > Ken Ketner, KA5ELD
> >         Postal Address:
> >
> >                 Institute for Studies in Pragmaticism
> >                 Room 304A Main Library Building
> >                 Texas Tech University
> >                 Lubbock, TX 79409-0002
> >
> >         email:
> >                 Office  b9oky at ttacs.ttu.edu
> >                         Home    ketner at arisbeassociates.com
> >
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