5 Nov
2013
5 Nov
'13
10:01 a.m.
At 12:00 -0600 11/5/13, <Cory> wrote:
After further investigation: The PSU does seem to be
giving 12V and -12V
where it should, and on the board there is continuity between 12V on the
power commector and 12V on the molex...so nothing went completely open
there.
Cory,
Caution, wild-ass debugging guesses based on insufficient
data follow. Fred's was the correct response, "what is it doing?"
That said, I had trouble with one of these machines, and
finally traced it to the power-on-reset mechanism. There are a
capacitor and resistor in parallel, holding the CPU in reset long
enough for power to get up and stable. The resistor was fine, the
surface-mount capacitor was intermittent (grr!) short. So the machine
would run for an indeterminate period before the capacitor would
short, pulling it back to reset state.
Replacing the cap fixed the problem, though I have not played
with the machine much since. I think at least some of this story is
in the archives, not sure.
YMMV of course, but this sounds like a possible analog to
your trouble; if your equivalent cap is dead short, the CPU would
never get out of reset and the machine would look "dead" even with
power. Let me know if you need more info, I can pull the box out of
storage and try to look it over and test again.
Good luck!
--
- Mark 210-379-4635
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