Folks,
Got a PDP 11/04 on the bench here at work with an H777 (54-11599) PSU in
with a sticker on it that says 'pop, bang & smoke'. I've downloaded the
maintenance printset from Manx (yay Manx) but before I even begin I've
noticed a terminal block on the transformer that indicates a jumper between
terminals 1&2 and 3&4 for 115V and an additional jumper between 2&3 for
230V.
I've not checked the prints, but I would have thoguht it was jumper 1-2
and 3-4 for 115V and jumper 2-3 _only_ for 230V. As you've worded it, it
suggest you mean to jumper all 4 terminals for 230V (which I suspect
whould chort out the mains!).
This third jumper is missing so have the owners of this PDP just put 230V
across a PSU jumpered for 115V?
Well, if they plugged it into 230V, it sounds like it. But 115V outlets
are not totally unheard-of in UK factories, etc, so it's possible it was
strapped for 115V and used on 115V
Incidnetally, there's at least one DEC PSU -- and I think it might be
this one -- that has an inrush limiter resistor that's shorted out by a
relay once the supply has got going. If this relay doesn't make properly,
the resistor gets left in circuit, and gets hot and bothered as a result.
-tony