Nick,

FYI,

Just getting back into this machine.  The wiring of my TT-69A matches the schematic (fig 2-79) & wiring (Fig 3-3) diagrams of NAVSHIPS 91713, but not 2852WD & 2852WD, rev D. (maybe they did in earlier versions?)

My TT-69A & NAVSHIPS 91713 do not have the polar ("LINE") relay and the signal line filter connects directly to terminals C5 & C10 (TB-751).

Thanks,

Duncan,
K2OEQ


On 7/14/2025 3:03 PM, Nick England wrote:
Seeing the cloth-covered wires made me think it was an early model. I have a TT-47A with a LESU that looks very similar except no loop supply which looks like a ham add-on.
The TT-47A LESU is Navy model SB-154A. Teletype model LESU5/103
Manual is at
https://www.navy-radio.com/manuals/tty/tt47a-91713-5207.pdf

Wiring diagrams 2852WD and 2853WD are in 573-100-400
https://www.navy-radio.com/manuals/tty/573-100-400.pdf

Nick England K4NYW
www.navy-radio.com


On Mon, Jul 14, 2025 at 1:59 PM Duncan Brown <[email protected]> wrote:
I'm checking out a M28KSR that looks like it has had some major rewiring done to it.

All the jumpers that are normally on terminals 4-14 of the cabinet terminal blocks have been removed.  There were two, 4 conductor, external cables connected to the cabinet terminal block, all unterminated, except for a 2k power resistor (loop current limiter) connected across  C10-C11.

I see no designator on the LESU and the color codes of the cable from the LESU to to c5 - c14 do not match the colors I see on 2874WD (or any others).  The LESU has what looks like a Line Shunt Relay, a 120VDC power supply (with monitor jack), a Motor-Stop relay and an 120VAC input panel ( lamp switch & fuses). See picture enclosed.

Can anyone identify this LESU?

I tried to remove the LESU by removing the big screws.  The LESU was loose, but would not come out, apparently because of the front panel power switch extension mechanism.  I expected it to disengage when I lifted up the LESU, but it did not.  Is there something in the switch extension mechanism that has to be removed/released?


Thanks,

Duncan
K2OEQ