At 10:39 AM 12/18/02 +1300, you wrote:

>Normally I'd have not worried about it, as Spehro
>suggested, but I just happened to come across a web page the other
>day that traced faulty operation of a piece of equipment to electrolytic
>caps de-forming

It simply isn't a problem under the conditions you describe; we have
direct experience with hundreds of thousands of electrolytics under
similar conditions. *If* a cap is stored for 20 or 30 years and then
suddenly subjected to high voltage then you might see this kind of
problem, but CERTAINLY not with 50mV, which is essentially the same
as leaving them in the shipping bag from an electrochemical POV.

As to the life of electrolytic capacitors, if your item is line-powered,
the power supply capacitors will typically fail a couple of times before
small signal parts fail- due to the higher temperatures present from ripple
current and proximity to the transformer and regulator components.
20 year life is not at all unusual for this kind of part. Most likely
the product will be discarded by then. If you're really concerned, buy
quality brand name parts, but with few exceptions (like the ones we got
directly from the China factory in which about 5% had the ENTIRE RUBBER
BUNG MISSING, they are generally pretty decent (those particular ones
dried out pretty fast though).

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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