Re: Electrolytic caps and Apple analog circuits (semi on topic)

["Paul G." <carbide@egine.com>]

On Jul 8, 4:21 pm, winston19842005 <bjjlya...@bellsouth.net> wrote:
> On 7/8/07 3:20 PM, in article
> 1183922400.107788.278...@q75g2000hsh.googlegroups.com,"jsnos...@cimmeri.com" <j...@cimmeri.com> wrote:
>
> ...
>
>
>
> > ALL THAT SAID... what's the deal with electrolytic cap failures?
> > Anyone have any perspectives on the topic?
> > - Why do some apparently seem to last forever -- I have some here from
> > the 1950's that are still working -- and some fail some damn quickly?
>
> > - Are there any patterns to be discerned -- such as the smaller ones
> > last longer, or lower voltage ones.. etc?
>
> > - Are some brands better than others?
>
> > This is all very useful info to have when making repairs.    I
> > occasionally repair Apple power supplies or other analog circuits, but
> > haven't had enough experience to draw any generalizations.
>
> > If this topic has been covered previously, please alert me and I'll
> > search archives more carefully.
>
> > Thanks!
> > ~ J
>
> Www.badcaps.net
>
> Caps of course go bad over time, but the failure rate among the more recent
> caps (from the 90's up to now) is utterly ridiculous.
>
> Dell has had a lot of failures due to bad caps within the past couple of
> years, and the place I work at has seen a lot of them ourselves.
>
> Strange, like you said, how older caps were so much longer lasting. I have
> computers 20 years+ that still have good caps, no sign of leaking or bloated
> caps...

The RECENT flurry of failures is apparently due to the use of a faulty
electrolyte by Taiwanese capacitor manufacturers. See:
http://www.niccomp.com/taiwanlowesr.htm
That one is costing computer manufacturers big bucks in warranty
failures.

I'd guess the GENERAL trend might be due to things like the move to
switching supplies from transformers, using 85 degree C parts instead
of 105 degree C parts next to hot components, the compactness of
modern parts compared with old ones, etc.

-Paul