[GreenKeys] M28ASR Strange Loop issue...found?

[W2HX]

That didn't come through as expected.

[cid:image001.png at 01D9082A.669F12D0]



Try it again...

EXTERNAL LOOP (TRAFFIC) ---> KEYBOARD ---> TD ---> LPR (ON) ---> POLAR RELAY INTERNAL

LOOP 1 (KEYED FROM POLAR RELAY) ---> PAGE PRINTER INTERNAL

LOOP 2 (NOT KEYED, ALWAYS MARKING) --> LPR (OFF)





73 Eugene W2HX

Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos



-----Original Message-----
From: W2HX
Sent: Sunday, December 4, 2022 9:35 PM
To: Greenkeys <greenkeys at mailman.qth.net>
Subject: M28ASR Strange Loop issue...found?



Ok everyone. I've got lots of updated information on my issue. To recap, this ASR has been running very well for the last 15 years. Recently the loop-driven LPR (sits on the keyboard contacts) recently stopped working in the way it has for all these years.  I've spent the last week and have poured dozens of hours into understanding how my ASR is set up. It was set up by Jack Hart (sk) who knew what he was doing. Only problem is I didn't know what he was doing hihi.



Thanks to Nick, K4NYW who saved some of the materials from Jack, and thanks to me for never deleting emails, I was able to find some original correspondence with Jack dating back to July of 2005 when I first bought the machine from him. I studied the diagram for the WU 9797 LESU ad nauseum and learned a LOT.



Here is how my electrical is configured.



EXTERNAL LOOP (TRAFFIC) ---> KEYBOARD ---> TD ---> LPR (ON) ---> POLAR RELAY INTERNAL LOOP 1 (KEYED FROM POLAR RELAY) ---> PAGE PRINTER INTERNAL LOOP 2 (NOT KEYED, ALWAYS MARKING) --> LPR (OFF)



I have a DPDT switch mounted beneath the ASR that connects the LPR to one of two loops, either the internal loop (LPR OFF) and the external loop (LPR ON). In this way, when I don't want to punch tape from the external line, (OFF) it is connected to the internal loop and keeps the LPR in mark-hold (closed) at all times.



The problem (previously described poorly) was that when the LPR was off (mark-holding, LOOP 1) it would run open. I spent days working on figuring this out. I found that when I plugged an ammeter into the RJ (reperf jack) it would close the circuit and work properly! This made no sense because these jacks should be normalling (shorting) when a plug is removed. But in this case, it seems to be open circuit.



Ultimately, I must have damaged this jack when I was messing around learning about the electrical configuration which must have caused this problem. I wonder if anyone has any thoughts on this? I could attempt to pull the LESU open it up and repair it. And I probably should but seems like a bigger project than I'd like to take on at this moment. So I might just make a shorting plug to do the business.



In case anyone is interested, here is a video I made on the whole set up and you can see the problem firsthand. And you can see how the problem resolves with an ammeter in the RJ jack.



https://youtu.be/ULO6B07koDM





73 Eugene W2HX

Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos


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