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From: ian field on 6 Jul 2010 09:21
Just in case anyone else is having problems with one of these, I've just
fixed mine by doing a full PSU recap.

Yesterday when I went to use it, it switched on and immediately froze.
Unplugging for 30s and plugging back in - the 7-seg display ran through the
Klingon alphabet and then went blank.

All but 3 of the electrolytics looked cheap & nasty but read lower ESR than
I was expecting - but evidently not low enough for the PSU to work
correctly.

One of the electrolytics on the primary side is the error voltage smoother,
its very important that this is in good condition - as its only 1uF it
wasn't difficult to find a non-electrolytic replacement.

The 3 electrolytics directly on the cathodes of the 3 rectifiers were decent
quality with low ESR (I couldn't find any replacements with lower) I added
10uF multilayer ceramic chip capacitors on the print side.


From: Meat Plow on 6 Jul 2010 10:10
On Tue, 06 Jul 2010 14:21:44 +0100, ian field ǝʇoɹʍ:

> Just in case anyone else is having problems with one of these, I've just
> fixed mine by doing a full PSU recap.
>
> Yesterday when I went to use it, it switched on and immediately froze.
> Unplugging for 30s and plugging back in - the 7-seg display ran through
> the Klingon alphabet and then went blank.
>
> All but 3 of the electrolytics looked cheap & nasty but read lower ESR
> than I was expecting - but evidently not low enough for the PSU to work
> correctly.
>
> One of the electrolytics on the primary side is the error voltage
> smoother, its very important that this is in good condition - as its
> only 1uF it wasn't difficult to find a non-electrolytic replacement.
>
> The 3 electrolytics directly on the cathodes of the 3 rectifiers were
> decent quality with low ESR (I couldn't find any replacements with
> lower) I added 10uF multilayer ceramic chip capacitors on the print
> side.

I shot-gunned a PC Coolmax PSU, 650 watts. Just up and quit one day.
Could here a little snap has I plugged the 3 pin mains plug indicating
a current inrush on that side of the PSU. But replacing several caps
with new ones rated at 65c brought it back to life.

Next project is an Intel 915 mainboard that gave up after a year of use.
It had been used to begin with. It was in my son's PC and his PC just
froze. After that, no boot, no POST. I read somewhere that Intel was
notorious for using caps that lacked stability over time especially when
placed near heat sources. The new motherboards like the Asus MT4 series
advertise solid polymer caps that last 57 years at 65c. We'll see about
that :)
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