25 Aug
2016
25 Aug
'16
10:05 a.m.
It turns out the problem was the cab kit. I replaced
it with a spare and
the
machine worked great. On closer inspection I found
some corrosion and
possible evidence of a previous battery leak, so I am going to take it
apart,
check it and clean it up.
The other thing that made me suspect the cab kit is that the act of
pulling the
serial cable out (not unplugging the terminal) would
cause the machine to
reset. MicroVAX II does this if you switch off the console terminal while
the
terminal is connected.
Just a bit more info on this.
I tried cleaning up the corrosion, and that briefly seemed to make a
difference, but then I realised the problem persisted. I looked again and
realised that the corrosion around the DE-9 pins was a bit bad. Initially I
thought to solder some jumper wires around pins 2 and 3, but when the solder
would not melt very easily, I found that it kind of flaked off under a bit
of heat and physical pressure. This made me think that although I was
getting continuity with my DMM, the joint was not that good. So I desoldered
the whole DE-9 connector, cleaned the board with PCB cleaner and then
resoldered it back.
This seems to have fixed it.
Regards
Rob