On Sun, Apr 25, 2021 at 11:26 PM Fritz Mueller <fri...@fritzm.org> wrote:
> > > On Apr 24, 2021, at 7:02 PM, Josh Dersch <dersc...@gmail.com> wrote: > > If you have notes on re-creating the harness, let me know. > > Hi Josh, > > A few pointers -- I think I left some of these in a comment on one of your > fb posts, but will repeat here in case others may find it useful: > > * The wire list in the commonly available Jun74 11/45 engineering drawing > set is actually for the power harness, and not for the backplane. It > includes wire run lengths in inches, which is quite handy. I believe it is > for the newer harness, but there is much overlap. > > * The old and new harnesses are also schematically illustrated on four > pages of the drawing set marked "power systems configuration". These > drawings are complete and quite good. > > * Drawings for the power distribution board for the older wiring style > (vertical at the back of the cabinet) are hidden in the Jun74 11/*40* > engineering drawings (upper right of sheet BA11-F0). > > * What I did was use the wire list lengths as a guide, cutting each run to > length plus a little extra. I then started with the H742s on the bench, at > the regulator and power monitor mate-n-loks. Then put the H742s in the > rack with the CPU cabinet, and worked my up and over the and then down > along the along the backplane toward the console, bundling and trimming to > length as I went. > > * A good ratchet lock crimp tool makes a big difference here. You want > one with a die that can handle 14 AWG, and on which will crimp both the > electrical and strain-relief parts of the pins in one go. > > * Sticking with the original wire color code also makes it a lot easier > not to get lost and later to double check and troubleshoot your work. I > used MTW ("Machine Tool Wire"), which is available from wirebarn.com at > 14 and 18 AWG in most of the necessary colors and in 25 and 100 foot > lengths (I think the 18 AWG purple I had to find separately on eBay, but I > have lots of leftover of that and will gladly send you some.) > > * I skipped wiring for most of the regulators in the bottom H742 (I have > regulator F there, but none of H, J, K, or L are populated) because I don't > have any core or fastbus memory in my system. I figure I can add this > later if I ever do find myself with either of these. > > Good luck! > Thanks! I may get started on that fairly soon, we'll see how ambitious I'm feeling... Sorry for the delay, but finally, here's a pile of pictures of the +5V ECO on the backplane. Let me know if you need more detail on something: https://1drv.ms/u/s!Aqb36sqnCIfMpMAqf_6YvmsEEU-T0A?e=Y6WBfV - Josh > --FritzM. > >