ASR-33 problem

23 Jan 2004

...

   My ASR-33
has recently started to apply 20V pulses to my TX+ line.  I 
 By Tx+ do you mean the keyboard loop? In other words, is it Tx on the
 teletype or Tx on the computer?  
 Sorry, I mean Tx on the computer.  The 20V appears on the + side of the loop
 going to the TTY's printer, whenever the printer is actually printing.  The
 computer doesn't like it much, either :-). 
I guess I'd start by unplugging the 9 pin connector on the selector 
magnet driver bracket. If you still get 20V on the loop, then there's a 
short somewhere in the wiring on the call control unit (probably on the 
relay). If not, then there's a problem in the selector magnet driver. 
There aren't that many components in there, so it can't be too hard to 
test the lot!

-tony

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ASR-33 problem