[GreenKeys] Model 28 asr problems

[Nick England]

It isn't clear what you mean by "the magnets come on" and "the magnets
stop" ?

The printer is either
SPACING (magnets not energized and machine running open like it is trying
to continuously type blanks)
or MARKING (magnets energized and machine not typing or not running open)
or TYPING characters

You have a 9797 WU electrical service unit like this one?
http://www.navy-radio.com/tty/28asr/rest4/28asr-lesu-210.JPG
The wiring diagram is here -
http://www.navy-radio.com/manuals/tty/wd/wu9797wd.pdf

The outside signal loop runs through the polar relay - the loop is polarity
sensitive.
If you have the polarity wrong, the machine will run open.
Terminal 1 is negative, terminal 2 is positive

ON SOME MACHINES (as penciled in on that wiring diagram) terminal 2 was
grounded to the chassis - this is a bad practice!
Unhook whatever wire is grounding your loop, because your signal loop might
already have negative grounded.
This drove me crazy and shocked me until i figured it out.....

Good luck!
Nick England K4NYW
www.navy-radio.com


On Thu, Feb 6, 2025 at 2:02 PM abowman89 via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> So im back working on my western union m28 asr machine that's been kicking
> my butt.   I have most of the problems ironed out but I'm down to this,
> the printer magnets only come on with the line test switch on and the ms
> switch to the right.  If you turn the machine switchon on it or line test
> or ms switch, the magnets stop. Any good guesses?  My gut says it's
> something in the electrical service box but I haven't spotted it.
>
>       Andy b
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