From: cctalk-bounces at classiccmp.org
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
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) . I find that the
printset is always the best manual to look at first :-)
 As you all know by now, looking at on-line documentation is rather
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
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
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
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
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
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
found a generic plug from the local electroncis shop
was a perfect fit as
replacement for a broken one in an HP9820 calcluator
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
Inch size (to fit USA built stuff mostly). And I need odd sizes like
Metric sizes (needed on just about anything modern-ish, and everything
BA sizes. BA is a strange thread used mostly on older British stuff. You
BA spanners to work on Creed teleprinters, for
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.