Teletype

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Mon Jun 2 18:16:00 2003

>From: ard_at_p850ug1.demon.co.uk
>
>> Whenever I type anything I just get a left-arrow. I am blaming the
>> 1818-23/-21 for this. Shouldn't I?
>
>Maybe. Does the Model 33 work correctly when switched to 'local'? If not,
>then you certainly have problems in the Teletype. If it does work in
>'local' mode, then you might still have problems in the Teletype, but
>problems with the interface are also possible.

Hi
 It is also possible that he has the wrong speed gears/motor.
A 60Hz motor will run in local with 50Hz connected but the
Baud rate to the outside will be wrong.
Dwight

>
>>
>> OK; current loop.
>>
>> Would this explain a resistor (14 Ohm, big) in the slot of the KSR would
>
>Are you sure it's 14 ohms? I remember a multi-tapped power resistor with one
>tap being about 1400 ohms in the standard current loop electronics for
>the Model 33.
>
>> get extremely hot when off this loop? Also; Hans Pufal, I would be most
>
>And I think it does run hot. When switched to local, the teletype is
>_still_ a current loop device, but the transmitter (keyboard contacts),
>receiver (the selector magnet driver -- the little module with 2
>transsitors in the Teletype electronics chassis) and a 'local' power
>supply (which includes that resistor) are all in series. A current loop,
>but one entirely inside the Teletype Model 33.
>
>-tony
Received on Mon Jun 02 2003 - 18:16:00 BST