17 Jul
2015
17 Jul
'15
2:10 p.m.
What I am wondering about, though, is the extra current they draw while
they are forming up while the power supply is running. The capacitor
might survive it (not get so hot that it fails), but the things supply
the higher than ordinary current to it might not. Killed a bridge
rectifier on a PDP-12 that way.
JRJ
On 7/17/2015 1:31 PM, tony duell wrote:
It is generally a good idea to re-form
electrolytic capacitors in power
supplies, and to bench check the power supplies (under some kind of
load) before actually applying power to the whole unit.
I am not sure either would have done much good here. The OP said it
ran OK for an hour or so, when you test a PSU on dummy load you
typically do it for a lot less time than that, Incidentally, DEC PSUs
of this type run fine with no load in my experience
Also I have found the capacitors in these units to be very reliable. They
can fail, of course, but virtually all the DEC bricks I have are on their
original capacitors. I think I've replaced more chopper transistors than
capacitors in these.
-tony