6 Feb
2017
6 Feb
'17
2:38 a.m.
From: Mark Hare
For a more permanent solution, I designed a simple
adapter board that
connects to the BERG 40 connector on the DL11-W and converts it to a DB9
serial port ... I also ordered a 40-pin (non-IDE) ribbon cable to
connect the DL11-W to my adapter.
When I connected everything, the 11/34 would start but
no lights would
appear on the front panel. I tried disconnecting the adapter but leaving
the ribbon cable plugged into the BERG connector, but the problem
persisted. When I removed the ribbon cable entirely, the unit powered on
with no problems.
That's extremely odd. There isn't a pin on the DL11-W Berg connector which
should be able to cause anything like that kind of behaviour. The only
_possible_ thing I can think of, looking at the list of signals on the Berg,
is that you are grounding +5 (TT). Either that, or your DL11-W has some
serious issue?
Since this is a straight-through ribbon cable, I
don't see what could be
causing this problem.
Me either. But clearly it's not just a straight-through ribbon cable....
I myself wouldn't have gone that route; one can obtain 40-pin IDE/DuPont (they
are all .1" spacing pins, and basically interchangeable, module keying)
connector shells, and female pins for same; I would have made a custom cable
to plug into the Berg with that, to a DE-9S or DB-9P connector (depending on
whether one wanted one wired as a DCE or DTE). (I myself make such cables, but
to a DB-25S connector, and then use a commercial DB-25P to DE-9S adapter when
needed.) Oh well...
Does the DL11-W still work, using the jumper cables kludge?
Noel
6 Feb
6 Feb
2:58 a.m.
New subject: PDP 11/34a Serial Communications Problem
I believe I have found the problem. Upon closer inspection, I noticed
that the ribbon cable that I am using is terminated in such a way that
the conductors are exposed on the outside of the top of the female
connector. 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. I
covered the exposed ends with a piece of electrical tape and the whole
setup now works precisely as intended.
Frankly, I'm just glad that there doesn't appear to be any lasting damage.
Thank you Michael and Noel for your help; I'm sure I'll be back with
more questions as I make progress with this machine.
Yours,
Mark D. Hare
markhare at buffalo.edu
University at Buffalo
B. S. Civil Engineering '16
M. S. Structural/Earthquake Engineering Student
On Sun, Feb 5, 2017 at 3:38 PM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu> wrote:
From: Mark
Hare
For a more permanent solution, I designed a
simple adapter board that
connects to the BERG 40 connector on the DL11-W and converts it to a DB9
serial port ... I also ordered a 40-pin (non-IDE) ribbon cable to
connect the DL11-W to my adapter.
When I connected everything, the 11/34 would
start but no lights would
appear on the front panel. I tried disconnecting the adapter but leaving
the ribbon cable plugged into the BERG connector, but the problem
persisted. When I removed the ribbon cable entirely, the unit powered on
with no problems.
That's extremely odd. There isn't a pin on the DL11-W Berg connector which
should be able to cause anything like that kind of behaviour. The only
_possible_ thing I can think of, looking at the list of signals on the Berg,
is that you are grounding +5 (TT). Either that, or your DL11-W has some
serious issue?
Since this is a straight-through ribbon cable, I
don't see what could be
causing this problem.
Me either. But clearly it's not just a straight-through ribbon cable....
I myself wouldn't have gone that route; one can obtain 40-pin IDE/DuPont (they
are all .1" spacing pins, and basically interchangeable, module keying)
connector shells, and female pins for same; I would have made a custom cable
to plug into the Berg with that, to a DE-9S or DB-9P connector (depending on
whether one wanted one wired as a DCE or DTE). (I myself make such cables, but
to a DB-25S connector, and then use a commercial DB-25P to DE-9S adapter when
needed.) Oh well...
Does the DL11-W still work, using the jumper cables kludge?
Noel
2876
days inactive
2876
days old
1 comments
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Mark Hare