Hi --

We have a 3036 in our university which is loved (and feared) by our
students. Our problems started two years ago when we relocated it from
one room to another, and the 24v leg of the power supply failed shortly
thereafter. We had it repaired -- 3 Darlingtons and a capacitor, to the
tune of $300 -- but it failed again within a week.

Then last year when the 18v leg started failing, I got some great help
from this forum. I think I chased down some possible shorts, and the 18v
leg is good again. But I wasn't able to figure out the 24v problem. Now
that it's summertime and the students are gone, I'm ready to take it on
again.

The technician who fixed it the first time seems knowledgable, but is
suggesting putting in a 24v switching power supply on just the 24v leg.
Does that make sense? It seems wrong to me.

It's been a long time since I went through the 24v supply, but it seemed
to me that I got 24v from the transformer, but not from the next link in
the chain (the huge capacitor?). The tech mentioned something about a
diode bridge, and of course the Darlingtons. (Yes, we now have 2" of
clearance on all sides, but that hasn't helped the 24v supply.)

Any suggestions of a plan of attack?

Matt