[GreenKeys] 28 TD questions

Mon, 21 Jan 2002 13:58:45 -0500

Gil,

The LXD runs on a normal 130VDC loop and the control solenoid
should work on 110VAC. Before you get too worried about
the pins...look very carefully to make sure the pins
have not slipped below the plate and/or they're not blocked
by dirt in the slots. Kinda unusual for them to be
broken.
The rear connections should have the tape out/tape jam
switch, the control solenoid and the mark (space)
contacts. Easiest way to determine the mark/space
contacts it to hook up a VOM and run a tape through (once
you fix the pins, of course). I'm guessing that the three-pin
connector is the signal generator's mark/space/common
connections. They come from the small closed metal
box in the machine. I don't have any military wiring
diagrams, but the presence of the two terminal strips seems
to indicate it's not overly different from a standard
Teletype TD. I'd recommend putting a resistor in series with
the control solenoid just to be safe. There's always the
possibility that it's a 48V coil.

Jack WA2HWJ
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of gil smith
Sent: Monday, January 21, 2002 12:11 PM
To: [email protected]
Subject: [GreenKeys] 28 TD questions

Hi folks:

I have an M28 TD standalone unit (TT-603/UG) that I'd like to get working.
I connected AC and the motor turns the mechanism just fine.  When I use a
plastic rod to push the "run" solenoid gizmo, it feeds paper tape and I can
see the sense pins coming out etc.  I have two problems though:

First, I only see three of the five sense pins come up, so something is
broken inside.  I have a spare LXD37 reader mechanism (serial 15!) that
looks in decent shape, but I can't just swap the LXD out since the
driven-shaft/gear portion is different.  I think I can either swap the
driven-shaft parts, or the sense pins parts, whichever is easier.  Anyone
have words of wisdom on dismantle and reassembly?

Second, I have no documentation, so I am curious about the wiring.  There
are two 9-position terminal strips inside.  The lower strip has AC
connections for the line cord, internal power switch, and chassis ground --
this was easy enough to figure out.  The upper terminal strip has
connections to what appears to be two shielded-twisted-pair wires, with all
six connections available.  These wires go to a delta connector underneath
the LXD reader mechanism.  I presume one of these cables provides a
low-voltage supply for the run solenoid, and the other one looks like it
goes to a switch. Then there is what looks like another
shielded-twisted-pair cable that is terminated in a 3-pin circular
(mil-type) connector -- I presume this provides the data switch contacts
for the loop.  I can likely figure this other stuff out as well, but if
someone knows connection information, I'd appreciate it.  Specifically,
what voltage does the run solenoid need, and what loop voltage are the data
contacts rated for?

thanks,

gil

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