[TUHS] PDP 11/34a Serial Communications Problem

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Feb 6 08:01:06 AEST 2017


    > From: Mark Hare <markhare at buffalo.edu>

    > I believe I have found the problem.

Excellent!

    > Looking at the DL11-W, I saw that there is an uncovered trace on the
    > circuit board just below the pins of the BERG connector.  It appears
    > that the exposed conductor ends of the cable were making contact with
    > this trace, which shorted the entire cable together.

Shorting any set of DL11-W pins together still shouldn't have caused that
symptom, AFAICS.

I'm too lazy to pull out a DL11-W, and prints thereof, to check, but I suspect
that what actually happened is that trace carries some 'interesting' signal,
and it got grounded 'or something' by the exposed ends of the flat cable.

    > I'm just glad that there doesn't appear to be any lasting damage.

Indeed! I was worried about that...

	 Noel


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