Smoke From PSU Socket

[Rob Jarratt]

> -----Original Message-----
> From: cctalk-bounces at classiccmp.org [mailto:cctalk-
> bounces at classiccmp.org] On Behalf Of Tony Duell
> Sent: 28 March 2011 20:10
> To: cctalk at classiccmp.org
> Subject: Re: Smoke From PSU Socket
> 
> > > If a properly-funcitoning DELNI draws anyhting like 10A from the
> > > mains, I will eat one :-). I am sure it would be fine.
> >
> >
> > I am absolutely sure it will be fine in this respect.
> 
> I have now dione what I should have done ages ago amnd looked at the
> DELNI printset on bitsavers (under dec/ethernet IIRC) [1]. I find that the
> printset is always the best manual to look at first :-)
> 
> [1] As you all know by now, looking at on-line documentation is rather
more
> work for me than for most people, which is why I didn't instnatly look at
> bitsavcers to see if there was anything useful.
> 
> Anyway, I was somewhat suprised by the PSU. It's not an SMPSU. At least
> one of the regulators looks to be a switching type,, but the power supply
> starts with a mains transformer (running at 50Hz or 60Hz). The primary
> windings of that transformer go to the nromal series/parallel switch and
> then to the mains input. Oh yes, there's a fuse in series with the live
wire.
> 
> Now, 10A, even at 110V is over 1kW. a 1kW (more correctly 1kVA)
> trransformer is a big lump of iron. I doubt one would fit in the DELNI
case.
> So I am sure a 10A filter will be fine.
> 
> When you replace it, make sure that the wire that goes to one end of the
> fuseholder goes to the live output tag on the filter. It's very clear from
the
> schematic.

Thanks, I will make sure I follow your instructions on this.


> 
> [Modifying the case]
> 
> > > And if it isn';t, a file will take care of the problem :-)
> >
> > Hmm... I definitely don't want to do that. From the pictures on the
> 
> Well, agreed, I'd rather mont have to do it, but it's better to slightly
enlarge
> the hole than have a non-working device, isn't it?

Of course, I just want to minimise alterations and will try to find a better
alternative before making alterations.


> 
> > Schaffner site it *looks* like it will fit the cutout just fine. I'd
> > like to
> 
> I think it will, these things come in fairly standard sizes.
> 
> Admittedly it was just an IEC320 plug, not one with a built-in filter, but
I
> found a generic plug from the local electroncis shop was a perfect fit as
a
> replacement for a broken one in an HP9820 calcluator made over
> 25 years earlier. No cutting, filing or drilling needed.
> 
> > measure the old one, but I can't get the damn thing out at the moment.
> > One of the nuts holding it in is in an awkward position, annoyingly, I
> > don't have the 1/4" spanner you need to undo the nut and pliers won't
> > reach. I am going to have to find a suitable spanner first.
> 
> SInce when have pliers been a substitue for a spanner??? 


When I don't have a suitable spanner :-) Don't worry, a suitable spanner is
now on its way.



> Darn it, I don't
> even like using adjustable spanners if I can avoid it.

I don't like them either, but in this case I don't even have an adjustable
one that will reach into the awkward spot where the nut is.


> 
> Incidentally, I find I need 3 sets of spanners to work on classic computer
> stuff :
> 
> Inch size (to fit USA built stuff mostly). And I need odd sizes like
11/32"
> sometimes.
> 
> Metric sizes (needed on just about anything modern-ish, and everything
> European).
> 
> BA sizes. BA is a strange thread used mostly on older British stuff. You
need
> BA spanners to work on Creed teleprinters, for example.

Gosh, I remember BA sizes when building my KeilKraft kits as a kid and
wanting to put engines and radio control in them I never had the money for.


> 
> AAnd yes, open-end, ring (box end?) and nutdrivers are all useful.
> 
> -tony