21 May
2012
21 May
'12
12:51 p.m.
Greetings;
I received a new (to me) MicroPDP11/23 that I was fiddling about with over
the weekend. After testing out the supply voltages, and then putting the
system together enough to get serial out of it, there was a pop, a whoosh
and a rather exciting ejected plume of smoke from one of the upper fans.
http://www.kiwigeek.com/misc/PDP1123_Cap1.jpg
http://www.kiwigeek.com/misc/PDP1123_Cap2.jpg
Yes, they do this from time to time. It's aprt of the mains filter
sircuit, and they often fail for no really good reason.
The capacitor is mounted on the sub-board in the PSU that the IEC
receptacle is on.
The markings on the back show this is a PME271M622, but I'm having trouble
sourcing a replacement. Most of the places I usually look about are
showing no stock or ridiculous minimum orders. On eBay (shudder) there's a
similar model, but it's marked as an "X2", and I'm not sure if
that's an
acceptable replacement.
Should be fine. From the fact that it;s 0.22uF (220nF), it's going to be
across the mains, not from either side of the maisn to protective ground.
In which case there are no special safety requirements 9Like it must not
be ablto fial short-circuit). OF ocurse the capacitor ahs to be able to
stant 250V AC continously.
An XT one would be fine.
-tony