24 Feb
2010
24 Feb
'10
3:39 p.m.
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.
This third jumper is missing so have the owners of this PDP just put 230V
across a PSU jumpered for 115V?
Thanks!
--
Adrian
www.binarydinosaurs.co.uk
24 Feb
24 Feb
9:26 p.m.
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
25 Feb
25 Feb
9:51 a.m.
On 24 February 2010 21:26, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
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!).
You are indeed correct, there's 2 windings in the transformer that 2&3 join
together. After I'd dismantled it and worked this out someone told me it's
a 115V box anyway!
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
Yup.
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.
I'll check tomorrow. Didn't have a chance to do much else with it yesterday
other than a visual to check for obviously blown components of which there
appear to be none, certainly nothing that looks like it's let the magic
smoke out...
--
adrian/witchy
Owner of Binary Dinosaurs, the UK's biggest home computer collection?
www.binarydinosaurs.co.uk
7:02 a.m.
other than a visual to check for obviously blown
components of which there
appear to be none, certainly nothing that looks like it's let the magic
smoke out...
I think this supply ios a mains-side switcher. So check the chopper
transsistor and mains rectifier diodes before you go too much further.
-tony
5420
days inactive
5421
days old
3 comments
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participants (2)
-
ard＠p850ug1.demon.co.uk -
binarydinosaurs＠gmail.com