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...
24 Apr
24 Apr
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
25 Apr
25 Apr
11:26 p.m.
On Apr 24, 2021, at 7:02 PM, Josh Dersch <derschjo
at 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!
--FritzM.
26 Apr
26 Apr
12:03 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Fritz
Mueller
via cctalk
Sent: Monday, April 26, 2021 2:27 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: DEC PDP-11/45 backplane +5 ECO
fb
posts,
On Apr 24, 2021, at 7:02 PM, Josh Dersch
<derschjo at 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 but will repeat here in case others may find it
useful:
Thank you for not hiding your experience on Facebook!
* 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.)
--FritzM.
And thank you for the pointer to Wirebarn. Much better stock than at Home
Depot :->.
https://www.wirebarn.com/14-AWG-MTW-MACHINE-TOOL-HOOKUP-WIRE_c_23.html
https://www.wirebarn.com/18-AWG-MTW-MACHINE-TOOL-HOOKUP-WIRE_c_25.html
Those assortments are great. Also the single color in various lengths:
https://www.wirebarn.com/14-Gage-Machine-Tool-Wire-MTW_c_111.html
https://www.wirebarn.com/18-Gage-Machine-Tool-Wire-MTW_c_84.html
-----
paul
2 May
2 May
1:25 p.m.
On Sun, Apr 25, 2021 at 11:26 PM Fritz Mueller <fritzm at fritzm.org> wrote:
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
On Apr 24, 2021, at 7:02 PM, Josh Dersch
<derschjo at 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!
--FritzM.
2:28 p.m.
On May 2, 2021, at 1:25 PM, Josh Dersch <derschjo
at gmail.com> wrote:
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
Oh, this is great, thanks! It's very interesting to see how this was implemented.
I think I will need empty my backplane soon in order to do some lower fan maintenance, so
I will probably pull my backplane and implement this at that time.
1087
days inactive
1095
days old
5 comments
3 participants
participants (3)
-
derschjo＠gmail.com -
fritzm＠fritzm.org -
pbirkel＠gmail.com