wrote in message
ups.com...
Thanks again for the pointers. I checked the .2ohm resistors, and
although I wasn't able to check all of them, one may have been shorted.
It's in a tough spot to get at with the DMM probe (which may have been
grounding out somewhere else), so I'll remove everything from the
chassis. That looks to be a pain, but I think if I'm going to end up
replacing components, I'll have to do that anyways.


Just a point. The 0.22's *should* read short circuit or thereabouts - 0.22
ohms is almost a piece of wire ... What you are looking for with those is
them having gone open circuit, which they often will if the transistors
attached to them, are short circuit ( path = "+" rail, Tr C-E s/c, 0.22R,
0.22R, Tr C-E s/c, "-" rail ) = lots of current between rails, = blown
emitter resistors.

As far as your meter probes go, I keep a piece of silicone rubber sleeving
over my probes, so that only the last 1mm is exposed. I also keep them filed
up to a needle point, which helps to stop them slipping.

Arfa