DEC H777 PSU

Adrian Graham binarydinosaurs at gmail.com
Thu Feb 25 03:51:15 CST 2010


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



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