[GreenKeys] M33/32 AC Receive Loop

[Teletypeparts]

Jon,

What you described is normal.  When the 32 ASR was in service, the central office reversed the polarity to connect the Telex and then to shut it down when finished.  

Good work on the ckt bd.

Wayne




-----Original Message-----
From: Jon Penner <jjpenner at hotmail.com>
To: greenkeys <greenkeys at mailman.qth.net>
Sent: Tue, Feb 11, 2014 8:36 pm
Subject: Re: [GreenKeys] M33/32 AC Receive Loop



Hi John,
Found my problem. CR2 on the bottom Western Union board was open. Once I replace it, the external loop came to life.
Does the process of reversing the direction / polarity of yours start/stop the motor? That may only apply to M32 telex machines.
-Jon
Austin
 

From: jjpenner at hotmail.com
To: greenkeys at mailman.qth.net
Subject: RE: M33/32 AC Receive Loop
Date: Thu, 6 Feb 2014 09:35:59 -0600


Hi John,
I'm having similar problems with my M32. 
Works great on local (buttons and everything). 
When I reverse the external loop, the motor shuts off like it's supposed too.
Forward loop turns the motor on but machine runs open.
When I'm in local and Forward external loop current happens, buzzer sounds for 2 seconds and then goes online, again with no selector magnet hold.
When "online" and running open, turning the dial causes it to go local and hold the magnets.
So everything works as the book says, except the selector magnets holding on a forward external loop connection.
Currently tracing and highlighting schematic to see where the missing link is. 
73
-Jon
N5MHI
 
John Ball ball.of.john at gmail.com 
Tue Feb 4 01:28:13 EST 2014 

My teletype and UCC6 functions fine in Local but in Line it's the opposite.
 have a serial 20ma current loop adapter which uses 4100 and 4200
ptocouplers and I could not get the machine to both stop marking or
ransmit anything to the adapter when wired up. For testing I put it in half
uplex mode and bridged terminals 6 and 7 which caused the selector magnet
o energize and idle the machine. When I checked the voltage at the same
erminals I saw it was reading -0.5v DC and 6.6v AC. I understand the send
oop is AC but isn't the receive loop DC? I've looked at all the diodes on
he circuit card without desoldering them and none were obviously blown or
horted. Is it worth it to pull them off and check anyways or should I be
ooking elsewhere? I did have CR1 short out about a month ago for no obvious
eason. I replaced it and CR2 with matched values.
-John



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