MicroVAX II Console Garbling Characters

Rob Jarratt robert.jarratt at ntlworld.com
Thu Aug 25 12:05:58 CDT 2016

> It turns out the problem was the cab kit. I replaced it with a spare and
> 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
> 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
> 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.



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