On Jun 1, 2021, at 4:16 PM, Steve Maddison via cctalk
<cctalk at classiccmp.org> wrote:
After a few years in storage I'm finally getting to play with my PDP-11
stuff again. Figured I'd start small so rolled out the 11/23. PSU looks
fine, pulled all the cards and checked voltages, no problem. Shortly after
however, some magic smoke was released from the block in the back where AC
comes in and the power switch is mounted. The only other thing in there is
a big old line filter. Judging by the smell, I suspect a filter capacitor
has given up the ghost. I'd check, but the whole thing is soldered shut so
not exactly easily serviceable. Would I be correct in thinking such filters
aren't entirely necessary and could just be bypassed? It looks like the
manufacturer (JMK) is still going so a new replacement might not be out of
the question. Whether I could find one with the same mounting holes etc. is
another question I've not looked into yet.
I'm not sure if you're talking about the same sort of device I had trouble with,
so FYI: the Pro power supply is a box the size of an old-fashioned Bible, with a CEE power
inlet at one end. That inlet is actually part of a sealed metal box containing a power
Mine decided to let out its magic smoke, in quite spectacular fashion, stinking up the
workshop and leaking evil looking black tarry stuff over the insides of the power supply.
But the supply appeared to be intact in other respects.
I couldn't find a matching filter, so instead I found a functionaly similar filter
that's physically smaller. I then created an adapter plate with a hole to accept the
new filter, and a flange sized to match the old one. My sheet metal skills aren't
great so it doesn't look all that professional but it's plenty good to get the job
FYI, the new filter is this one:
-- about half
the size of the one it replaces.