11 Nov
1997
11 Nov
'97
12:19 p.m.
On Tue, 11 Nov 1997, Tim Shoppa wrote:
A clamp-on AC ammeter is one choice - and its something that everyone
with minicomputers should own or be able to borrow :-). You can buy them at
Radio Shack, among other places.
That reminds me... I really must start seriously looking for a Tektronix
current probe for my 'scope.
A series light bulb is another trick. With all the loads removed from the
outputs of the regulators, the PSU shoulds run with (say) a 200W light
bulb (or enough smaller ones in parallel to equal this). The bulb should
be dim/out. If it's glowing brightly you can be sure that there's a short
somewhere.
This trick is more use on SMPS's where faults don't just trip the
breaker/fuse, they also blow expensive chopper transistors. I never power
up a repaired SMPS without some kind of limiting...
[...]
1) A short somewhere on the secondary side (in one of
the regulators,
say). This will obviously cause too high a current to flow in the primary
circuit
How do I check that? I've never played with voltages over 24V before. It also won't hurt to do a continuity check on the
breaker. If the
connections aren't what you think they are, you've got a problem!
Unless it's one of those breakers with a separate connection for the trip
element (used in the RX01/RX02 I believe), I can't see how misconnecting
the breaker will cause it to trip only when the load is plugged in.
Tim.
-tony