On Fri, 18 Apr 1997 22:17:11 -0400 Steve Bookout <sbookout@mnsinc.com>
writes:
>Are there any good guidelines for reforming electrolitic caps???
>
Hi Steve, et al
I have used a similar type of bench supply for over 30 years to reform
electrolytics. In the supply here there are current and voltage meters
plus a 0 to 500V adjustment. I start at 0 volts and slowly bring up the
voltage while watching the current meter. An arbitrary leakage current of
10ma maximum is used as a guide (That was a value given to me 30 years
ago and it seems to be OK) and the voltage is continued to be brought up
to the maximum capacitor ratings.
The final phase is to parallel them all...takes a ample supply of clip
leads...and bring them up slowly again to max voltage. Then let them cook
for an hour or so. Ideally, the current should go down to only a few ma.
per cap. Discard any that show heat above what is expected of a new cap.
A problem with electrolytics is that they develop a chemical memory based
upon the voltage they were used at. It may be hard to get them to reform
at higher voltages.
When used in a series string the equalizing resistor value should be
selected so that the voltage drop across any one cap does not exceed 5%
of the group. Use one R value throughout; typically 50K to 100K depending
on how well the capacitance values are matched.
Any other ideas out here....if we can get off of power regs long enough?
73....Carl KM1H
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