[GreenKeys] my 28ASR

[Jack]

OM,
That's an old Western Union ESU, made by them and placed into the 28ASR by
them. That might be one of the many machines that were let go in Allentown,
PA, many years ago. I have one, too. (In fact, got it from an SK ham's
estate in Allentown.) I would recommend that you just bypass the entire ESU
and wire to the magnets and trace out the keyboard contacts. The only use
for the ESU might be the AC power control to the keyboard.
I do not have any diagrams, but someone else on the list might. If the relay
isn't up to snuff, it'll drive you crazy trying to get the machine to work.
You have to set bias current and all sorts of other settings that are not
really relevent to ham use.

Jack WA2HWJ