Re-Forming Electrolytics

[Bob Groh WA2CKY]

Yes, that is capacitor reforming.  The general principle is to increase the voltage gradually while keeping the dc current at a low level (less than a couple of mA).  When you reach the maximum operating voltage, you let it sit there and the current should drop off to near zip. If, at any voltage level, the current does not back off or it starts to increase, you have bad capacitor.  I have some sources on this whole process but I am not home right now so I don't have them readily available. 

73
Bob, WA2CKY


----- Original Message ----
From: Rinkie & Ron Pollack <rinkies at ROADRUNNER.COM>
To: HEATH at LISTSERV.TEMPE.GOV
Sent: Friday, May 18, 2007 8:08:50 PM
Subject: [HEATH-TEMPE] Re-Forming Electrolytics


There has been quite a bit of discussion on reforming electrolytics with a
variac, milliammeter,  transformer, and rectifier.

I have a couple of old Heathkit Capacitor Checkers which work quite well.
In addition to the bridge circuit for checking capacitance, they have a
feature for checking leakage using variable voltage up to 600V (I think).
It is current limited using a resistor, and a "magic eye" tube to indicate
leakage.  I've found that old electrolytics initially show leakage,  but
often show no leakage after a few minutes at a lower voltage, the eye opens,
indicating no leakage.  By increasing voltage incrementally, many times the
cap will show no leakage after a few minutes.

I'm not sure if this qualifies as reforming the capacitor.  I'm not much of
a technical guy;  does anyone have any thoughts on this?

Ron K2RP

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