[GreenKeys] Finally getting time to work on 28 ASR I have

[Jim Haynes]

What you have there is a Western Union ESU.  I have recently worked out
most of the wiring on one.  I'm on the road right now, but can tell you
more about it when I get home.

Is there a polar relay in the ESU?  Does the machine run "open" when you
turn it on, and when you hook it to the loop?  Reason I ask is that it
is sensitive to polarity, so you may have to reverse the connections
to the loop on the TU.  PJ is a jack for measuring current in the printer
selector magnet and PP is the rheostat for adjusting it.  BJ and BP are
for measuring and adjusting the current in the bias winding of the polar
relay - using the bias winding is optional, and is needed for a neutral
signal current, and is disconnected for polar signal line.  The other
jacks and pots are a little less clear to me.


Jim W6JVE