Hi,
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?
If it is on the keyboard loop, I'd look for shorted contacts on the
line/local selector relay (it's burried in the call control unit, not on
the selector driver module though). Maybe the internal loop supply (used
in local mode) is somehow getting onto the line connections.
-tony