After a design review meeting this afternoon which had much more
mechanical than electrical, I decided to reverse engineer the PCB and
wiring in this model 28 stock ticker strip printer.

I think I understand what's going on.

I saw in one of the documents it uses a bipolar signalling scheme and
the diagram bears that out.  There is a bistable mercury polar relay on
the board.  All transistors are germanium. I was surprised that the
selector magnets are driven from a 25 volt supply; they must be
relatively low inductance?

I'm not sure if attachments go through this list but if so I included
what I drew from my little exercise.

Initially I thought maybe the 1/4" jack was the input but that is not
the case.  The input is via a terminal block.  I tried applying 10 volts
and the selector pulled in.

Which led to a problem:  something seems locked up as what looks like
the main clutch is just clicking and nothing past it turns even if I
release the selector magnet.  I can turn the motor by hand to see where
the clutch releases so don't need to run the motor.  I wonder what is
going on.

At least I have the electronics figured out.

Peter

P.S., if the diagram doesn't make it through, give me your email address
and I will send it to anyone who wants it.

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