24 Apr
2021
24 Apr
'21
7:02 p.m.
On Sat, Apr 24, 2021 at 1:36 PM Fritz Mueller via cctalk <
cctalk at classiccmp.org> wrote:
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:
For sure. I have it on a shelf in the garage to keep it relatively safe
while it's out of the chassis, next time I'm out there I'll take some
pictures.
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...
Yes, I was looking at the service docs and it does seem to match the
earlier wiring scheme. If you have notes on re-creating the harness, let
me know. The molex shells actually survived the heat (with a couple of
exceptions) so I should be able to reuse them. Looks like I'll just need to
order up a ton of wire and pins (and a crimper, probably).
I'll get the 15V boards out of the H742's this week.
- Josh