IIe power supply problems

[kjhass@sandia.gov (Joe Hass)]

Wizards of the Net:

I'm trying to help a local elementary school keep their IIe's running and
have found what appears to be a bad power supply.

The machine will boot properly when it's warm but the power supply won't 
come up if it's cool.  When it's cool the +5 output is at about 1.1V, the
-5 is at about -1.1V and the +/- 12V outputs are proportionately low.
Sometimes, if it's not too cool, the voltages will slowly rise and then
the supply will suddenly come to life and be fine.  I know it's the supply
and not the motherboard because I've swapped them with another machine,
and I've tried heating the supply alone with a hair dryer. Also, when the
supply is cool but disconnected from the motherboard the positive voltages
are about 1% above nominal and the negative voltages are about 10% more
positive than nominal.

I can't see any cold solder joints or obviously bad components.  The
machine is of 1985 vintage and the supply was made by Astech.

Any diagnostic suggestions would be appreciated, as well as pointers to
a low-cost vendor for a new supply. I'm an EE so I have a passing
familiarity with switching power supplies, but I don't have the schematics
for this guy.

TIA,
Joe

-- 
Joe Hass               | library clever_sigs;          | My opinions are my own
kjhass@sandia.gov      | use rock_and_roll.verses.ALL; |   not Sandia's and
Sandia National Labs   | use lineprinter.art.ALL;      |   not the DOE's