18 Oct
2013
18 Oct
'13
5:58 p.m.
Hi all,
I have a couple of 3511D terminals from 1976 or so. Both can send data just
fine to my PDP-8/M or my laptop, but they refuses to receive anything now.
Both worked several weeks ago, though they started to get a little flakey.
I probed the MC1489 in one and found that the received signal looks very
nice. After that, though, I haven't been able to test much more without a
schematic. Tracing it out is difficult thanks to the opaque IC sockets.
I've tried to ohm out where the output from the 1489 goes to no avail,
other than to pin 20 of the DB-25 connector. Why would they be sending a 5V
TTL signal out the RS-232 line?
Does anyone have any information on this terminal? Some images can be found
in this album: http://imgur.com/a/fDVDH
Thanks,
Kyle