Power supplies

[<JCA31@MAINE.MAINE.EDU>]

I now have in my posession several II's that have dead power supplies.
All the supplies appear to be the same design internally, and all
exhibit the same symptoms: No juice. The main switch is good, and when
the resistance of the input of the supply is measured, it starts at
about 1.1 or 1.2 megohms, (as soon as the switch is turned "on"), and
then climbs slowly, like you get with caps charging up. Btw, this
1.2M impedance seems to be the same on power supples that *do* work.
I decided to trace the schematic out, for the hell of it, until i got
to where the transformers are, and abandoned that for lack of info on
the taps. In any event, all the components "look" good, with visual
inspection.

Since they all seem to be the same design, and about the same age, i'm
suspicious that there's something that typically goes wrong in these
beasties. If anyone can provide hints on what that might be, not only
could i repair the supplies (and thus the machines) i do have, but when
the others inevitably go, it won't be an irreversible loss.

Further, to show my gratitude, if anyone does help me with this, (and even
if they don't), and i can solve the problem, i will gladly write the
solution up, and contribute to the entire community, hopefully in a form
suitable for inclusion in a faq. I will waive all "rights" to the
contributed material, so long as it is known that i will assume no
responsibility for the use of the material. (You get what you pay for,
but that doesn't mean i wouldn't try to make it right!) .. Maybe,
just maybe, we'll someday have a faq that the faq-keeper undestands is
not something that can be held hostage in a petty personality war.

thanks.
-j