USR quad modems... (ontopic - really!)

Don THX1138 at dakotacom.net
Fri Aug 18 13:53:47 CDT 2006


Billy Pettit wrote:
> Don <THX1138 at dakotacom.net> wrote:
> 
>> TIP:  An embroidery hook works wonders for fishing wirewrap wires
>> out of a nest without too much damage!  ;-)  (but you have to
>> find the right size hook to ensure a "good grab" on the wire)
> 
> For those of us who go back to the dawn, there was the spring hook, a
> beautifully functional tool used on the relay machines.  They worked great
> on the thick wire mats.  I still have all of mine and even today find the
> spring hook to be one of the most useful tools around the shop.

Yup.  I have a nice assortment of similar telco tools (including
armature adusters, etc.).  Unfortunately, MaBell used heavy
gauge wire on most of those things --whereas most of the
wirewrapped devices I have worked with used 30AWG kynar
or teflon wire.

I also have a really neat pair of needle nose that have the
jaws machined to act like no-niks.  You learn early on that
these are *only* to be used for stripping wire or holding wire
and NEVER to carry any "load"!  :-/

(I wish I could find a commercial source for these)

> Another tool I found useful was a jewelers device to hold rings for
> soldering.  It looks like a pair of tweezers with the ends bent out so they
> can't touch.  You squeeze it, stick it in the wire mat, and release.  The
> tension holds the wires apart.  We made a bunch of copies using piano wire
> and put shrink tubing over the ends.

You can use the pliers that are used for *outer* clip rings
to do this -- with a rubber band around the handles.  (i.e. the jaws
OPEN as the handles are drawn together).

> If you get a chance, look at the 6600 or 7600 in the Museum.  Seymour loved
> those dense wire mats - he used wire lengths to tune his systems.  If you
> worked on one of his machines, you spent a significant part of your working
> hours buried in wire up to your forearms.

The same was true in the "tester" -- you had to resolve time to
1ns resolution so lots of wirelength issues, loading devices
to get the right transition times, etc.

For a one-of-a-kind machine (I think we *might* have built
two!), it wasn't too bad.  But, I would dread having to do this
in a production environment!

> The worst was the Cyber 170 machines.  They were twisted pair 30 gauge wire
> mats.  If you weren't careful, the pins bent and touched.  And there was
> what we called "tingles".  The broken piece off the end of a wire would
> disappear into the wire mat and eventually short two pins out.  Even more
> fun, if you were tuning clocks, the power was on, so you could watch the
> path of the tingle by the little sparks.  Always happened on a Friday night,
> of course.

If you only *partially* unwrap the wire (i.e. take the "tension"
out of the coil) and then deliberately *break* the wire where
it connects to the insulated portion (this is where the wire
typically *wants* to break) you can fish out the insulated
tail and then carefully lift the expanded wire coil off of the
WW pin (using the fancy needlenose pliers mentioned above).

OTOH, if you *pulled* on the insulated portion before breaking
the wire *or* tried to pull the "coil" (tingle?) off, you were
almost guarantees to end up with tiny bits of bare wire
suspended in the ratsnest!  :(

> One of the worst nightmares I worked on was a machine that the engineers
> working on, had set their coffee cups on top of the cabinet and forgot about
> them.  This was before the styrofoam cups, just waxed paper.  It soaked
> through and dumped the coffee down into the wire mat.  We tried for a few
> days to fix it but finally had to scrap the entire chassis. Per the Peter
> Principle, the chief suspect was later promoted to be my manager.

Ha!  And later ran the company, no doubt!  :-(



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