[GreenKeys] Signal Line Connection - RS-232 Interface

Wed Jun 12 13:38:47 EDT 2019

Photo of line / local relay attached.

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Ken Wiebe
Sent: Wednesday, June 12, 2019 9:14 AM
To: Thomas Tillson via GreenKeys
Subject: Re: [GreenKeys] Signal Line Connection - RS-232 Interface

Thanks, Clay.  I am planning a tracing and documentation session this weekend.  Should be enlightening.  What does the line/local relay look like?  Is it one of the things in that pic?

Your power block is very different from mine.

Ken

On Tue, Jun 11, 2019, at 23:11, Clay Archer wrote:

My 35 ASR has the line / local relay on that block with the power connections (and power outlet and fuse, see attached photo).   My interface terminal block (and power line block) is on the same bracket at the line / local relay.   Three of the four wires of the signal lines connect to the line / local relay (see attached schematic).    If you can find your line / local relay you may be able to trace out your signal connections.

    Your 35 looks like it has been really worked over.     I had several modifications on my 35, and I traced them out and documented the changes before I put the connections back to the “correct” locations.   You may need to spend several hours tracing out connections and comparing it with the schematic.   You will probably never be able to exactly match the schematic, but it should get you close enough to make things work.

    I also have one of those relays that you show in another post (like you said you have in a box).    I don’t think that it’s your line / local relay.    The one in my 35 sits in the call control area next to a transformer and never seems to engage in any mode I can select, but everything seems to be working on my 35.     

Clay

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Ken Wiebe
Sent: Sunday, June 09, 2019 9:35 AM
To: Thomas Tillson via GreenKeys
Subject: Re: [GreenKeys] Signal Line Connection - RS-232 Interface

Can't find pins 5-8 for the signal line.  I found pins 1-4 for the power.  They're under the plate in the attd pic.

Also notice in the attd pic the blk and red plug jacks marked ckt ground and sdg/rcvg.  I'm thinking those might be the half duplex terminals 5 & 8 (?)  But 6 & 7 unaccounted for.

Ken

On Thu, Jun 6, 2019, at 19:18, Ken Wiebe wrote:

----- Original message -----

From: Ken Wiebe <me at networkguy.com>

To: Thomas Tillson via GreenKeys <greenkeys at mailman.qth.net>

Subject: Re: [GreenKeys] Signal Line Connection - RS-232 Interface

Date: Thursday, June 06, 2019 08:41

Thanks.  The next goal for my 35 project is to interface it with an RS-232 device via the converter circuit.

As I prepare to do that, I am wondering about the signal line itself.  Setting RS-232 aside for the moment, in a real world scenario from yesteryear, where does the loop current come from (power source)?

Remember I'm a newbie.  So, if I connected my tester to the 35 transmit terminals and typed, would I expect to see anything happening?

I guess I'm looking ahead to what I would do next if my RS-232 experiment doesn't work first try.  Is there a test or tests I can perform to isolate the cause of the 35 not transmitting/receiving?

Ken

On Thu, May 30, 2019, at 23:01, Clay Archer wrote:

The shorting link is for half duplex operation with I/O on terminals 5 & 8.   Remove the shorting link for full duplex with send loop on terminals 5 & 6, and receive loop 7 & 8.     When I got my 35 ASR it had been rewired incorrectly and caused it to be looped in line mode.    A good schematic of the ASR is available at https://www.blunham.com/Misc/ASR35/   The terminal block is the one below where the power cord attaches (at least on my 35 ASR).

There are several good designs for RS232 to 20ms current loop.    There is one that uses two opto-isolators and has fewer parts, but the one you show works well too.

Clay

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Ken Wiebe
Sent: Thursday, May 30, 2019 6:19 PM
To: Thomas Tillson via GreenKeys
Subject: [GreenKeys] Signal Line Connection - RS-232 Interface

As you may know, for the 33 ASR several people have designed and built circuits to convert current loop to RS-232.  Example, I think Mike Douglas may be a member of greenkeys and here is a link to his:

http://altairclone.com/teletype.htm

Question:

What about the 35 ASR?

I need to do this for the 35.  I couldn't find much online so I turned to the 35 wiring diagrams in an attempt to find the signal line circuitry equivalent to the 33.  On the 33, it's four pins on the P2 connector which equate to the terminal strip pins 3, 4, 6, 7.

I think I found the relevant diagram for the 35, please see attached.  Something called "T" power terminal block, pins 5-8.

Anyone know where this is?

Sidenote:  See the note in the attd pic, "REMOVE LINK".  It looks like that link sets up a loopback, right?  That may explain why my 35 seems always to be in Local mode?

Anyway, I don't know where that "T" block is, and if you all could give me a sanity check I'd appreciate.

Am I on the right track you think?

Thanks!

Ken

PS  I also attd Mike's schematic for the 33 version of the RS-232 adapter so you can see what I'm making comparisons to

Attachments:

*	ASR35FullCiruit.pdf
*	20190424_225436.jpg
*	20190611_222714.jpg

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