28 May
2013
28 May
'13
2:46 a.m.
Cant help with the pulse transformers but Iv sucsesfully used 4 x 2N2222's
on a dil header to replace the quod transitor packages on a Dec core driver
for my Lab 8.
Dave
----- Original Message -----
From: "Josh Dersch" <derschjo at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, May 27, 2013 7:31 PM
Subject: Re: Sourcing DIP Transformer replacements
On 5/27/2013 2:33 AM, Dave wrote:
On 27/05/2013 00:38, Josh Dersch wrote:
Right, they're not logic chips, I misspoke :).
I've started looking at what it's going to take to get the memory in the
Imlac running again. There are two core assemblies in this machineand
they're both in pretty bad shape as they were exposed to moisture for a
long enough period that they accumulated quite a bitof corrosion on the
control logic. (The cores themselves seem to be OK).
I went over the better of the two assembliesand cleaned the legs of
every socketed IC. In the course of doing so I found maybe 10 chips
with legs that were falling off. I took alook at a random sampling of
chips from the worse of the two assemblies and every single one of them
has legs that are corroded through. So I'm going to be replacing a lot
of chipsif I want to get these running again.
Most of these are 7400-series logicand aren't hard to find. However,
there a set of components that I'm not too familiar withand I'm not
having much luck finding replacements. Now that I have the schematic I
at least know what they are(had no luck looking them up based on the
labels on the chips), they're described as "Transformer, 60uH",
"Transformer, 6uH" and "Transformer, Square Loop" and have part
numbers
of 517A0024, 517A0023, and 517A0021.
The chips themselves that are in my machine are labeled as follows (for
the 60uH variant):
14201
NPIPA-2581
<date code>
These are in 16-pin DIP packages. I'm going to need to replace quite a
few of them.
Any ideas of a modern replacement? (Any idea where to source NOS or used
ones?) I can provide pictures if that'll help.
Thanks,
Josh
These are almost certainly pulse transformers, not "chips" as such,
so
real miniature transformers. Try a google search on "core memory pulse
transformer" here are two I found usefull.
http://www.dtic.mil/dtic/tr/fulltext/u2/045016.pdf
https://sites.google.com/site/wayneholder/one-bit-ferrite-core-memory
Given that I wonder if its possible to salvage the original "innards" and
mount them on a 16-pin dip carrier. Have you tried opening one up or are
they fully encapsulated in a solid material. If they are solid is there
enough material left to solder to a 16-pin carrier. I think photos would
help. Finding modern replacements sounds fun and expensive (about $5
min).....
They're fully encapsulated in plastic / resin. For some of these it may
be possible to solder to a new carrier, but some are pretty far gone and
it might be more of a challenge to get a good connection.
I've put up a picture at:
https://plus.google.com/u/0/photos/117997069161125071032/albums/58769649993…
And yeah, $5/each is not going to be cheap. And I also need to replace a
number of multi-transistor packages (Q2T3725's) which seem to go from
$7-$10 (if I can even find them). I'm definitely going to try the repair
route first, but it would be good to have a source for replacements just
in case.
Thanks,
- Josh
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