🚀 go-pugleaf

Folks,
 I was just trying to get my Wyse 99GT to talk to an 
IBM RT, and when I couldn't get it to, i thought I'd better try getting
it to talk to istelf first. By shorting pins 2 and 3 together on the
DB25 connector on the back of the terminal, anything you type should be
echoed back to the screen, but it wasn't. Now the funny thing is that it
will talk to my other computer and my modem, but not to itself. I check
the voltage swings on the transmit data line coming out of the terminal,
and it went from +5.17 to -5.17 volts. This is certainly within RS-232
spec, so the terminal should be able to talk to itself. I had all
handshaking disabled, so I know that's not the problem. 
   It's not such a terrible problem, as the terminal does indeed talk to
the computer it's normally hooked up to, but *ALL* terminals should be
able to talk to themselves in the manner stated above, and I'm pretty
sure I used to be able to do this with this terminal. I'm just wondering
if this is a sign that something is out of adjustment or is going bad on
the serial ports on my terminal.  Anyone else with experience with Wyse
99GT's ever have this problem? 
Thanks for any help or advice,
  
Russell Hoffman
rh2y+@andrew.cmu.edu