[Gllug] Power Supply loaner in West London?

[Russell Howe]

On Thu, Sep 23, 2004 at 06:56:37PM +0100, Phil Reynolds wrote:
> Purely random - totally different styles of use. It is often due to
> actually defective capacitors - Abit boards are particularly prone but
> two of the ones I have dealt with were Jetway.

DISCLAIMER: I don't know what I'm talking about (nothing new there,
then...)

An electrical engineer friend of mine (well, boyfriend of my flatmate)
waxed lyrical about electrolytics when I was telling him about my dead
KT7-RAID.

He said that electrolytics were often the first components to go, due to
leakage and drying out of water-based dialectrics.

Looking at the specs for the caps which failed on my board, they were
only rated for a few years, so they lasted their expected lifespan.

If you are looking to replace switching power supply capacitors (and
someone is *bound* to tell me I'm talking about of my arse here), then
you generally want low impedance, high ripple current electrolytics with
a voltage rating a bit higher than you would expect to put across it.
Instinct tells me double, but I'm no EE.

Also, go for the higher temperature ratings - apparently, the
temperature rating is basically a life expectancy, expressed in degrees
C - the higher the rating, the longer it's expected to last. Oh, and
avoid water-based dialectrics.

The above is reproduced from my somewhat hazy memory, so is probably
totally inaccurate, so don't assume it's exactly what I was told in the
first place :)

To give you some idea of the ripple currents you're looking to handle,
the caps which died were rated at well over an amp.

ISTR various websites selling "capacitor kits" for boards known to be
notorious for dying capacitors. I think one was badcaps.com, but google
should find them.

As an aside, he also told me about some trains (he used to work for
Alstom, before he went freelance). There were some large electrolytics
in these trains for some reason or other. They were located in the sides
of the cars, behind the panelling. Every now and again, they'd die, with
a nice bang, but the panels could never be found.

Turns out that the farmers bordering the railway were taking them and
using them to patch up animal shelters and feed troughs!

-- 
Russell Howe       | Why be just another cog in the machine,
rhowe at siksai.co.uk | when you can be the spanner in the works?
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