Well...
I put back the original resistors and, after some testing, found the first
problem.
The dummy load I used was not enough to drive the PSU.
So I connected an old MB, and the PSU came up with the correct voltages...
but...
-5V and -12V were 0 !
Removing the P9 connector, results in the -12V back.
I noticed, this morning, that the LM340T12 had a desoldered pin, and I
soldered it back.
After less than a minute, with the PSU running connected to the MB, the
LM340T12 were volcano-like hot. It's mounted back to back to the
LM7905, so they were both hot. But the LM340T12 was desoldered again.
I replaced the LM7905 with a spare (its pins were rusty, oxydated, corroded
and burnt :P ) but have only a doubt: can I substitute the LM340T12 with a
MC7812?
Lookin' at the datasheet it seems they're equivalent (BTW, the
LM340T12 has another marking, 7812).
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The R1 and R2 resistors are dummy load, but not enough to let the PSU
start without any external load. I found a similar behaviour in some IBM
original PSU (5150 and 5155).
R1 is slightly burnt, I think, because of the 23V on the +12V, when the
PSU was malfunctioning...
Now the area around R1, R2 is warm, not hot...
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