[GreenKeys] Searching for Answers.

[Steve Garrison]

Well the six wire option, plus the AC safety wire, has been discussed
between Nick and I.

There are two wire wound 300 Ohm resistors up under the base that, for the
life of me, I can't figure out why they are there.  Although they are shown
on the schematic I'm using as a reference, even though it doesn't 100%
reflect what I'm finding.

As for the ohm meter, it's been used extensively.  That's how the issues we
have discovered so far were isolated and corrected.  I think the ripping out
of all existing wiring and installing just the six needed wires is the going
to be the route we will take.  I have one more test in order before making
that decision, but that may not happen until tomorrow!

Steve G./N4TTY

-----Original Message-----
From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net>
On Behalf Of Harold Hallikainen
Sent: Sunday, July 18, 2021 3:49 PM
To: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Searching for Answers.

It's amazing how Teletype made something electrically simple quite
complicated.
There's a wire in there for every possible option. I find their schematics
very difficult to follow. Luckily, the one I have just powered up. The one I
had in high school was another story. I pulled out all the wiring and
brought out six wires (plus safety ground). A pair for the magnets, a pair
for the keyboard, and a pair for the motor.

The fact that you see full voltage with the motor removed and a very low
voltage when the motor is present makes me think there is a high impedance
in there somewhere. This could be an RC filter across a switch or relay.
Apparently some units have a motor control relay (I've never seen this, but
I see it in some schematics). If it is not present or is not operating, a
jumper would be required.
Also, the toggle switches used in Teletypes seem to go bad. I had to jumper
the on/off switch in my 14 TD to get the clutch release to work. I still
find it strange that they put that switch in that circuit when the tight
tape switch is a couple inches away. If anything, I'd expect there to be a
motor on/off switch. I now have it plugged into a switched outlet strip.

As has been pointed out, an ohmmeter as a continuity checker would be good.
The trick is figuring out where all the wires are supposed to go! You might
measure the voltage across the on/off switch with the motor present. Does it
go to zero when the switch is on? Is there a motor control relay?

Good luck!

Harold
https://w6iwi.org


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