Apple II Power Supplies

[pbauer@ATHENA.MIT.EDU (Paul H Bauer)]

For those of you that have had power supply problems!
 
        This week-end I descided to clean up my work bench and either
repair or throw out a few AII power supplies I had in various states of
disrepair. I made an interesting discovery on two supplies, one an aztec
(?) unit, and the other a dead unit from a late model platinum 2e. The
supply from the platinum unit was dead. After checking almost all of the
semi-conductors and finding them good I finally started looking at the
resistors and found a 100k 1 watt
unit that kick starts the supply was open. Replacing this resistor fixed
the supply. I then looked at the aztec unit. This unit woul sometimes
start but most of the time it would not. I looked at the same resister
(R3) which is a 150k 1 watt resister. I changed this to a 100k 1 watt unit
and the supply works like a champ.
 
        If you have a dead supply you might check these resisters as they
could be the culprit. The resister goes from the + rectified line side to
low voltage oscillator that drives the power switching transistor.
 
        pbauer@mit.edu