On Sat, Apr 24, 2021 at 1:36 PM Fritz Mueller via cctalk < cctalk@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: > > > 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. > 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. > > 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