[GreenKeys] 28 ASR Loop Help!

Wed Nov 30 20:56:46 EST 2022

In the KSR version those jacks are provided to plug in a meter to set currents.

https://navy-radio.com/manuals/tty/wd/wu9797wd.pdf  for the ASR seems to be similar in that respect.

LJ = line current
BJ = bias current on line relay
PJ = printer selector magnet current. 
RJ = reperforator selector magnet current.  

Obviously you can do other thing with the jacks once you understand why they are there in the first place.  

My first step if it were mine would be to understand what modification if any were made.

John, W9DDD

> On Nov 30, 2022, at 6:10 PM, W2HX <w2hx at w2hx.com> wrote:
> 
> Hi guys. I think I screwed something up in my 28ASR. Let me describe how I believe the loops are set up, how they used to work, the recent history of things, what it does now, and then solicit your thoughts on what dumb thing I might have done. I got this ASR from Jack Hart a long time ago and he had it set up as you will see it and it always worked (pretty much!)
>  
> My main loop power is provided by an ST-6. It comes into my LESU through the “LJ” which I think means Loop Jack. Here is a picture:
> https://w2hx.com/x/TTY/ASR%20Pix/20220103_214634.jpg
> BTW this is the same LESU as one of K4NYW’s ASRs. It is my understanding that the LESU then has a second, local loop with its own power supply.
>  
> At the bottom of my ASR I have a switch “ON/OFF”:
> https://w2hx.com/x/TTY/ASR%20Pix/20221130_182502.jpg
>  
> My understanding is that this switch is essentially a DPDT. Two inputs are (a) the main external loop and (b) the internal loop from the LESU. The output of this switch goes to the reperf.
> This switch allows me to send either external loop traffic to the reperf (ON) or a steady mark-hold 60mA current (OFF) from the  internal loop so that when I don’t want to punch the main loop traffic, it will keep the reperf in mark-hold.
> This set up has worked pretty well for more than 10 years.
>  
> In this next picture you will see some wiring. A pair of wires in a clear sleeve with blue spades coming in from the left and attaching to #132 top and #133 bottom. This goes to the DPDT switch and is looped into the main, external loop.
> https://w2hx.com/x/TTY/ASR%20Pix/20221130_184043.jpg
> Also in that picture you can see another pair of wires in a clear sleeve connecting to #141 and #142. This pair of wires also goes to the DPDT and this is connected to the internal (always mark-hold) loop. In the past I have tested these by disconnecting one wire and seeing the results. So I am pretty confident that what I’ve described is accurate.
>  
> I’ve recently been trying to learn more about the ASR and the loop arrangement. I wanted to learn more about the function of these other jacks (PJ, RP, BJ). So I took a ¼” plug (the right one, I forget PL-068? Something like that). With nothing connected to it, essentially creating an open loop in whatever I plug it into.  I put the ST-6 into mark-hold and the reperf switch on “off” which kept both the printer and reperf in mark-hold.
>  
> I then inserted the ¼ plug into PJ. And the printer began to run open (makes sense). I removed the plug and inserted it into RJ and the reperf began to run open (ok RJ must mean Reperf Jack). Both returned to mark hold when the plug was removed. The BJ jack had no discernable change when I inserted or removed the plug. All of this was a few days ago and everything seemed normal and I learned more about some jacks on the LESU.
>  
> A few days pass by and now there is change in behavior. It seems that the internal, mark-hold, loop is no longer working properly. When I operate the switch, I either get the reperf onto the main loop (good, as expected) or it runs open when it should run closed (bad).
>  
> So what I have I done in the recent few days that might have contributed to this issue. I have really only done three things.
>  
> I did the experiment with the jacks mentioned above
> I took a working ROTR and I tried to insert it into the RJ to see if I could get the ROTR to also work the same as the LPR reperf. For some reason it did not.
> In the picture above showing the wiring, I fixed that red loop of wire between #139 and #140 as it had pulled out of one of the spade connectors.
>  
> I don’t think #1 above would have killed anything, but I guess it is possible. #2 could have killed something, but why would it? It either would have put another selector magnet in series with the reperf loop or not?  I do not recall testing the system after I attempted to use the ROTR in that jack. #3 above it is very possible that I replaced this loop of wire in the wrong place. But like an idiot, I neglected to photograph where it was originally before I took it out. But I have no idea how I would test this theory.
>  
> Ok, very long email, probably hard to follow all of it but any thoughts or suggestions very welcome.
>  
> 73 Eugene W2HX
> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>  
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