Thread: Faulty SMPSU.
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legg legg is offline
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Default Faulty SMPSU.

On Wed, 19 May 2021 21:13:02 +0100, T i m wrote:

On Mon, 17 May 2021 15:43:12 -0700 (PDT), whit3rd
wrote:
snip

I assume the 3 legged device on the LV side is a switching transistor


TNo, that has to be the low-voltage rectifier (if it really IS rated for 20A, it has to
be heatsinked); if it's leaky it would be a quasi-short-circuit, and that will deliver
AC to the capacitors you replaced, which would kill 'em soonish.

That's the likely culprit, probably will need to be desoldered to find the part
number, and will be easy-ish to test. Sometimes there's two diodes, center
pin common, in this form factor.


Update: Whilst waiting for the smaller components to turn up I've de
soldered the two devices on the rear of the board to check the part
numbers and (as you say), the three legged one is a rectifier, a
'30H150C' and I've tested it with my DMM (diode test) and it checks
out ok on that (centre pin to both outsides, both ways round etc). I
hope it's good under load as they don't look as easy to find as the
switcher, a KA1M0800?

Cheers, T i m


Any change in performance with ANY of these part subs?

RL