[COFF] VT100 TX but no RX?

[segaloco via COFF]

Thanks for the help folks, turns out there's some corrosion on the STP (standard terminal port) edge socket inside.  The pins are supposed to short across the socket when a card isn't inserted, so corrosion or bent pins can cause trouble elsewhere.  After some scraping a loopback test of tying RX to TX finally works, so now I can get back to messing with the signal chain.  Loopback actually doesn't work on the other end either so maybe both sides have their own problems...but VT100 is looking a lot better now thanks for the pointers!

- Matt G.