Prophylactic replacement of electrolytic capacitors?

From: Rob Kapteyn <>
Date: Mon Jan 14 15:52:22 2002

I have not yet tried this yet --
In theory, electrolytics can be re-formed.
There is a very thin aluminum oxide layer that disappears after a long time.
Running current through the cap will rebuild the insulating layer until current will no longer go through it.

I want to reform the original capacitors in my Altair "in place" -- i.e., without unsoldering them.

I have the following setup in mind:

1. Insulate the computer from the world -- unplug it and put it on a rubber table.
2. Use ultra mini test clips to connect to both leads of a capacitor.
3. Connect the test leads to one of those lab power supplies that have adjustable DC voltage and a milli-ammeter.
4. Connect + on the lab power supply to + on the capacitor (very important).
5. Start at zero voltage and increase slowly while looking at the ammeter.
6. Stop increasing the voltage when the ammeter reads anything more than a few milliamps.
     (If it draws too much current, the capacitor will heat up and may blow up)
7. Wait for the current on the ammeter to drop to zero.
8. Continue to increase the voltage, and wait for the ammeter to drop until you reach the rated voltage limit of the capacitor.
9. Repeat for every electrolytic cap in the computer.

Has anyone done this ?
Will it work ?

Received on Mon Jan 14 2002 - 15:52:22 GMT

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