[GreenKeys] M28 - mystery LESU TT-47A/-69A

[Duncan Brown]

QSL
Agree, you need to keep all versions/editions of manuals.

One thing that is not in NAVSHIPS 91713, is the BREAK button on the 
keyboard.  This TT-69A is wired for it.

Army  manual for the TT-47A & TT-69A was TM 11-2229, but can't find a 
pdf copy on the internet.

73,

Duncan
K2OEQ

On 7/17/2025 3:13 PM, Nick England wrote:
> I don’t know what’s up with those WD. The cross-reference says they 
> are for TT-49A etc. but clearly they aren’t. Another example of why 
> hanging on to early versions is a Good Idea.
>
> Nick England K4NYW
> www.navy-radio.com <http://www.navy-radio.com>
>
>
> On Thu, Jul 17, 2025 at 3:07 PM Duncan Brown 
> <duncanancy at earthlink.net> wrote:
>
>     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 <http://www.navy-radio.com>
>>
>>
>>     On Mon, Jul 14, 2025 at 1:59 PM Duncan Brown
>>     <duncanancy at earthlink.net> 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
>>
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