Star Wars Power Supply

Hey all,

        Here's one from the Twilight Zone.....

        My Star Wars power supply has died twice in the past week or so,
both times with the same symptom....

        That Symptom: No +5V. The continuity of all fuses (and
fuse holders) is good. Tracing back uncovers wierdness with the
+10.6 VDC unreg. With the connector unplugged from the RA/II board, the
+10.6 VDC unreg will SLOWLY climb to around +10.6 VDC. When I say SLOWLY,
I mean over the period of time of about a minute or two. It climbs more
or less linearly from 0. When I plug the RA/II board in, the +10.6 VDC
unreg line doesn't get above a volt or so.

        This sounded like a leaky cap, so I replaced the big blue cap in
the power supply. That fixed it....for a little while at least. Now I
have the same problem again. My only guess would be the bridge rectifier.
  It, however, tests out OK using the "standard" diode test. I suppose a
possible explanation would be a weak bridge rectifier that can't deliver
the necessary current to charge up the big blue cap. I also thought it
might be a problem with some of the connectors, but they look clean and
check out with good continuity.

        So, has anyone run across a "weak" bridge rectifier before? It
seems to be an odd failure mode. Usually these things either open up or
short out, but I guess every once in a while they could do something in
between....

Joe
Received on Mon Aug 16 21:30:08 1999