T i m wrote
Clive Arthur wrote
T i m wrote


Long short, it looks like the 20A x 12V
'open frame' SMPSU has gone weak?

I'd check the rectifier bridge. One of the four diodes
blown and it becomes a half-wave rectifier.

I replaced the 4 output caps because of the blown one
and sorta as predicted it doesn't seem to have fixed it.

I can go round all the passive components and check the
smaller transistors but there are a couple of big devices
underneath (TO220 but bigger style cases), one 3 pin (FET
/ Transistor) and a 5 legged one (SMPSU controller device)?

I can probably check for the 400V or so on the input caps (and
any AC voltage present, suggesting those caps had gone dry?)
but there is little point spending too much time (or money)
on components, other than for the fun of possibly repairing it.

After changing the caps and powering it up with no load,
I saw a 'weak' (fluctuating) 12V on the DMM but it wouldn't
power up with a 5A load attached (it crowbarred).

Any thoughts?

More likely now that it's the main controlling ic that has gone flaky.