[GreenKeys] M19 Selector Magnet - magic smoke?

[John Thurmond]

This is my first post to greenkeys, but it's obviously *the* place to ask these kinds of questions...
I have a Model 19 that I saved from being scrapped from an SK's estate - I have never worked with teletypes, so this is all new to me.
He was an excellent radio restorer, and it appears to have been working when I acquired it (W1AW copy from 2005 still on the paper: https://photos.app.goo.gl/Lh5exkuvKiWi37yK8), but no guarantees there. It sat in my garage for 2-3 years, until I finallyfigured out what kind of project I wanted to do with it.
It turns on and "runs open" (no surprises), but after reading up quite a bit, I realized I needed to set up a 60mA currentloop to start testing it out. I acquired a 120V DC power supply, and I was able to get the selector magnets to engage.
With initial testing, the selector magnet did engage from about ~20V, and this got it to stop running open as expected.
However, due to my own idiocy and not reading the manual for the PSU closely enough, it turned out I was running 600mA, ratherthan 60mA through the selector magnet (I was foolishly relying on a current-limiting power supply, rather than using a resistor to limit current.)
After a few minutes, this generated a curl of smoke from the magnet, and I immediately cut the power.(https://photos.app.goo.gl/q6bYHMatyfvm1ZzT6). A brief test after it had stopped smoking had the magnet still engaging, so I decided tocontinue on with working on an interface.
Now that I have the interface built, I came back to testing the M19 today to see if I could get the interface working. However, I can't seem toget the selector magnet to engage at all. I am now running 120V through a 2K ohm 10W resistor, and the current is 60mA (for real this time).I checked the resistance, which shows ~1 ohm - my understanding from reading up on M15s is that this should be ~55 ohms?
I am (somewhat dangerously) relying on the previous owner's wiring - he connected to the selector magnet through the terminal strip on theback of the M19 (https://photos.app.goo.gl/S3ictP9W6iXpoFkS9), which again, worked before, but I thought it was worth noting *where* I hadconnected the over-current previously.
Have I cooked the selector magnet? Are there any other tests I can run to see whether it's working? Any other points of failure I shouldbe paying attention to?
I appreciate the collective wisdom of this group, and hope you can help.
-JohnT K5JBT







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