[GreenKeys] Model 28 Typing Reperf repair notes

[Nick England]

Now please don't exaggerate, George - repairing a 28LPR is surely no more
difficult than popping the lid off an integrated circuit and rewiring a
bunch of transistors with your Weller 200 watt soldering gun. While
standing on your head. Underwater. During an earthquake.
Seriously the 28LPR is the mechanical equivalent of an IC - All that stuff
is just crammed in there in totally inaccessible ways.

Info for the archives, helpful hints division -
Today was a banner day for me as I resurrected not one but two of these
beasts that I had previously set aside as hopeless. The culprit in both
cases were the eccentric assemblies that determine the movement of the
typewheel. If these things are misbehaving, the push bars will misbehave,
and if the push bar ain't behaving, then the associated bell crank, pulse
beam, and transfer lever won't behave either - and if the transfer lever
ain't behaving, your punch slide won't slide and so the tape doesn't get
punched. The shin bone is connected to the knee bone, the knee bone is
connected to the leg bone, and so forth......

The net result is that a failure in the typewheel positioning mechanism can
travel back upstream to infect the punch. Of course the other way can
happen too - if the selector doesn't activate the punch slides correctly,
the typewheel won't work right either. In my experiences today, the root
problems were gunked up eccentric assemblies, so the two pushbars connected
to each eccentric weren't acting independently. Some vigorous manipulation
of the push bars coupled with some solvent spray and relubricating seems to
have cured them - at least they are for the time being happily punching and
typing "the quick brown fox..."

So if your selector is selecting OK, one thing to look at is whether your
push bars are pushing (or not) when they should be.

YMMV, Void where prohibited by law, Past results are no indicator of future
performance...Always Practice Safe Teletypery....

Good Luck!
Nick England K4NYW
www.navy-radio.com


On Wed, Jan 15, 2020 at 4:46 PM George Hutchison <w7tty at centurylink.net>
wrote:

> GreenKeyers - - -
>
> As an aside, those who choose to venture into the "magic" of the model
> 28/35 perforator/reperforator and its rather astounding complexities are
> dealing with a series of devices that was assembled by a staff of extremely
> talented old ladies at teletype whose gift to the world was to assemble and
> make functional said devices.
>
> Jack Hart once told me that whenever there was a punch failure anywhere he
> encountered, that their solution was to requisition a new one from Teletype
> and send the "dead body" back for whatever treatment was deemed appropriate
> for it.
>
> I believe that assembly of a new one was far more cost effective than
> repairing a failed unit.
>
> I have worked on several in my time, and found it much wiser to find a
> functional one than to repair a failed one.
>
> More Later,
> George - W7TTY
>
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