Don wrote:

Hi,

I use a lot of external disk/tape/etc. enclosures or
my computer peripherals. These typically have ~60W,
dual output (5/12) supplies in them.

They are a "popcorn part" so, when one fails, it is usually
easier to grab a spare out of my junk pile and replace the
entire power supply than waste time trying to repair it.

However, I have one such supply that is dead AND has an
atypical form factor (long and skinny). So, finding a
suitable spare in my junk pile has been a problem :
(the supply in question is a Autec UPS65-2002) It is
functionally equivalent to the dozens of other supplys
that I have so I have temporarily replaced it with one
of those.

I figured it might be worth a few minutes to poke around it
and see if I can steal some components off another supply
to breathe new life into this one. (If not, I'll just pull
the disks/tape out of the enclosure and throw the whole
thing out in favor of another enclosure).

A quick look at the types of components on the PCB leads me
to make some guesses as to what the circuit topology is.

It looks like mains power passes through an input filter
(choke, snubber, etc.) and then rectified. Switching
transformer primary is chopped and controlled by a sense
winding on the xformer. "Center" tapped secondary (no doubt
assymetrically tapped) two legs are rectified and then LC
filtered to provide the final output. I assume some sort
of OVP watches one or both outputs as I see optoisolator
feedback across the transformer no doubt to shutdown the
chopper.

Can someone confirm my guesswork to be correct?

Nothing is visibly toasted. And, assuming this topology,
I'd guess the chopper is "opened". Of course, it is possible
that there is a failure elsewhere on the board/load but I
suspect it may have just opened from fatigue, etc.

I.e. is it worth hunting down a replacement part (out of the
scrap bin) for a "quick fix"? Or, are these a bit more
complicated to repair (in which case, tossing it all in the
hazardous waste recycling bin is more expedient).

Recall I am *not* particularly "attached" to this enclosure... :

Thanks!
--don

Circuit sounds about right, though there will likely be overcurrent
protection as well. As far as repair goes, just bin it, theyre often
sods to do.

NT