[GreenKeys] 35 ASR current loop connections....

[John, W9DDD]

See if any of this helps

https://www.blunham.com/Misc/ASR35/

John, W9DDD

On 4/25/2019 1:03 AM, Clay Archer wrote:
> My rebuild of my 35 ASR is going well.   I have just about everything 
> working in local mode.   Reads and punches tape and types correctly, and 
> can type and punch from the keyboard.   The rubber on the printing 
> reperf print hammer is missing, if anyone has a source please let me 
> know (p/n 173979).   I also need the paper tape spool holder,  I could 
> probably make something to do the job.
> 
> I’m ready to try it “on line”, but I need to work out the current loop 
> connections.    It had some cut wires connected to the lower 4 screw 
> terminals on the back of the power supply section (I think the book 
> calls it the “electrical service unit”).  The upper 4 terminals are 
> numbered 1 to 4 and is where the power cord connects.    The bottom 4 
> are numbered 5 to 8.   Terminal 8 has no connection.     On my 33ASR I 
> have looped the input & output with a current limited voltage (a small 6 
> or 9 volt battery usually works) so I thought I would give this a try on 
> the 35.   Connecting a battery to terminal 5 & 7 or 6 & 7 will stop the 
> chattering like it’s receiving a valid loop.   And it sometimes prints 
> random characters when I connect to these terminals.    However, when I 
> type in line mode the data goes to the punch instead of the printer.   
> The selector knob is set correctly to the keyboard-to-print position and 
> it works in local.    Using a scope I can’t see any pulses when I type 
> on the keyboard on any of the screw terminals (I applied a small voltage 
> as a pull-up).  I also found that if I jumper 5 & 7 or 6 & 7 (without a 
> battery) it acts the same way.
> 
> There are also 8 screw terminals on the back of the call control unit, 
> none seem to do anything.    Oddly, my call control unit consists of a 
> transformer and a relay.   The relay never seems to activate with any 
> knob setting or line/local.
> 
> Does anyone have any manuals on the 35 ASR?    All that I can find 
> online are for the KSR & RO.    The schematic for the KSR & RO shows 
> it’s quite different from the ASR.
> 
> Any assistance you can provide would be appreciated.
> 
> Clay
> 
> 
> 
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