23 Feb
2011
23 Feb
'11
2:02 p.m.
Try connectin
the PCB alone to the VT220. If it passes, try it on the
microvax too. If will at least let yoy know if the latter is likely to
work with a good keybaord.
I just got done trying this. No dice, with the membrane disconnected 3
of the LEDs light up constantly and that's it (no beeps or anything else). With the membrane connected I get 4 LEDs and a
few very short
(shorter than I recall under normal circumstances) beeps. So perhaps
the membrane isn't to blame in this case.
Thsi, AFAIK, makes no sense. A correctly working membrane assembly is
open-circuit between all conenctions. So the cotnroller PCB can't tell
whether it's connected or not.
-tony