Re: Power supplies

[<JCA31@MAINE.MAINE.EDU>]

After trying all the "obvious" checks, it looks like it may indeed be time
to desolder some caps. Here are the current facts:
- since that 'globar' resistor is in series with the main AC line, and
  since the resistance across the line looks the same as in good supplies,
  it seems a safe assumption that that piece is good.
- since the IIe's in question operated just fine when other, known-working
  supplies were connected, it seems that the motherboard is fine, and the
  problem must be in the power supply
- all the caps, when checked with an ohm-meter, looked like caps should look,
  but these were checked *in circuit* (yes, after being suitably discharged!)
- like the caps, the main switching transistor measured the way one would
  expect an in-circuit, functional transistor to look.

I'm not so sure about these last to checks being terribly valid, though,
with things in-circuit. Since the supply is divided roughly in half by
the transformers (one large, one small) in the middle of the board, a
logical thing to do would be to isolate which side of the supply the fault
is on. One way to do this would be to check the activity at certain points,
say, the transformer taps. This was the sort of arcane technical detail
i was hoping to find. (Stuff like "18kHz ramp from 0 to 20V from ground to
tap 4".. or something. The example is pure fiction)

The only way i know that i can get this sort of info is to (*shudder*) open
up a known-working unit and get the probes ..

thanks!
-j