Prophylactic replacement of electrolytic capacitors?

From: Gary Hildebrand <ghldbrd_at_ccp.com>
Date: Mon Jan 14 09:39:24 2002

Louis Schulman wrote:
>
> Old computer power supplies generally have big old electrolytic capacitors. When these go bad, they can
> cause real problems, and damage other components.
>
> The literature indicates that many of these only have a working life of 2000 hrs., or a shelf life of ten years.
> Obviously, this will be exceeded in old computers.
>
> So, should these be replaced if they exceed a certain age? For the screw terminal type, is it necessary to
> use "computer grade" capacitors, which can be fairly expensive? If one can't find the right value in the right
> size package, how much extra capacitance is acceptable? And any higher working voltage rating is OK?
>
> Enquiring minds want to know.
>
> Louis

IMHO, it depends mostly on who made the electrolytics. I have large
"computer grade" electrolytics from the 60's, salvaged from Ampex VTR's
that are still 100%, and have never failed in over 30 years.

OTOH, the cheap electrolytics found in consumer grade electronics seem
to dry out and fail on a yeary or biannual basis. One of the worst
failure rates I've seen is the teeny tiny 160VDC electrolytics; I just
replace then no matter what and usually that cures the problems.

The best way to check those #$%#$%^# caps is to use an ESR meter. And
only then should yo buckshot them. And replace them with good grade
Spraggue or CDE if possible. I've had mixed to poor resutls with
Nichion, or other cheap Japanese caps sold by MCM Electronics.

Gary Hildebrand
Received on Mon Jan 14 2002 - 09:39:24 GMT