If I may go back to the original post topic for a moment, what model is that line printer
that is pictured? I'm on the lookout for a DEC LP32 to go with my 11/730.
Now on the topic of capacitors: The only component type that I replace on sight at this
point are the Rifa paper-dielectric EMI suppression caps. Had one go incendiary on me so
far, and I do a replace-on-sight routine on them because my hypothesis of the failure
mechanism(*) leads me to believe that they're all likely to burn up once the plastic
shell has developed any cracks. They're easy to recognize: Rectangular, with
transparent yellow plastic housings, which are usually crazed with fine cracks. Different
caps which should not be subject to the same failure mechanism are easily available.
(*) Paper dielectric is said to absorb moisture from the atmosphere if not sealed. So, I
presume that once the yellow plastic shell cracks from old age, moisture gets in, and then
the caps break down under power. I replace these with poly film safety-rated caps with
suitable ratings, since the poly film shouldn't absorb significant moisture even if
the housing seal fails.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/