24 Feb
2009
24 Feb
'09
3:38 p.m.
tiggerlasv at aim.com wrote:
On Monday, February 23rd, Charles H Dickman wrote:
I said "COULD"... ;-)
I don't know what the replacement looks like. I do know that the one
that failed for me failed exactly as you might expect. The short pins
first and then progressively away from the end. The fact that they are
at right angles and the natural way to make the harness is as you
described it doesn't mean that the correct way to make it is as you
described. My guess is that the replacement connector has beefed up
contacts that make load sharing issues moot.
I would like the photos. I can take them as attachments. I can add them
to my web pages if you don't mind. This has been something that I have
heard about since I started playing with my first microPDP-11/73 8 years
ago.
I did find FCOs BA23-I001 and BA23-I002. The replacement harness part
numbers are different. They are dated 7 months apart. Alas, no
description of the cable.
Thanks,
-chuck
> Robert Jarratt wrote:
> The harness in my system does not seem to match any of the
descriptions I
> have seen so far. The wires are not equal in
length, but it is not a
ribbon
> cable with IDC connectors either. The
connectors are black rather
than
> white. The harness wires do not seem
discoloured, but I believe that
this
> particular system may have only had light use
in its day. I have a
picture
> of the harness but I am not sure if the rules
of this list allow
> attachments.
>
The key point of your description is that the
wires are not equal in
length. This COULD be a bad thing.
On the BA23, the backplane and power supply connectors are at
right-angles to each other, so the 5-volt (red) wires are shorter
than the 12-volt (yellow) wires, as well as most of the grounds (black).
The same is true on the BA123.
As you can see in the ASCII art below, the 12v interconnect wires
end up being longer than the 5V wires.
This is normal.
I have a side-by-side photo of the old style cables, as well as the FCO,
however I don't have a convenient place to post it. If anyone wants it
for reference, let me know.
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