24 Apr
2021
24 Apr
'21
1:36 p.m.
Hi Josh,
Among the pictures linked from your message about the H742a parts, there is one picture of
you backplane. I have been looking for some time for information about the following
11/45 ECO:
KB11-00001 CODE: D May-72 [ECO]
Problem: Etch carrying +5V current from Mate-n-Lock pins to backpanel pins is not heavy
enough to carry required current. Correction: Run 24AWG wire in parallel with etch on
panels which already have Mat-n-Lock assembly installed. Increase thickness of conductor
with solder bead if Mate-n-Lock assembly not installed. PDP-11/45 system serial number 101
and later.
The wiring arrangements at the top of your backplane look to be a bit different from mine,
and I believe you may have this ECO implemented. While you have your backplane out, could
I ask that you take some closeups around the Mate-n-Locks along the top? I'd be very
interested to see the board traces and the details of the red bus wiring there.
Pictures of the toasted 11/45 suggest that the original machine had the older power wiring
scheme (distribution panel mounted vertically on back of cabinet instead of horizontally
at top of cabinet, etc.) although your KB11A serial number badge is >2000, which is
curious...