PDP-11/23 Debugging

Noel Chiappa jnc at mercury.lcs.mit.edu
Sat Nov 8 09:58:54 CST 2014

    > From: Noel Chiappa

    > I also discovered and repaired at least two cold-solder joints (one was
    > one of the pins for W1, the master clock control - the pin was actually
    > loose when I wiggled it). 

So it turns out that loose wire-wrap pins seem to be a systemic problem on
11/23's. I just discovered _3_ more on one single 11/23 board - two of them
the pins for the master clock! I put my finger-tip on them and wiggled, and
they were loose.

I'm not sure why it's the wire-wrap pins especially - maybe their physical
size meant that they have larger thermal inertia, and so need a longer heat
than the manufacturing process gave them, to bring them up to temp to prevent
a cold solder joint?

Anyway, if one has a flaky 11/23, that's definitely something to check.


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