22 Feb
2009
22 Feb
'09
6:48 a.m.
Correct the worng harness has unequal length wires and
the correct
one has equal length wires. The harness in question goes from the
Backplane to the PS.
The problem is with unequal length wires the connectors were sharing
the
load unequaly and the connecotr would overheat and fail sequentially.
It was more of a problem on highly loaded boxes.
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 system has a CPU card, two memory cards, three "half height" controllers
(disk, tape, async i/O), and a full height third party external expansion
storage card. I have the expansion storage box too, but to keep load on the
PS down I would be happy to remove the extra card until I make or get a new
harness.
Regards
Rob
Field service were (again, iirc) supposed to swap
these out if
they came across them. But if your machine has truly not been used
for twenty years, it ended up in storage relatively eraly in its
life and so may not have had a chance for some FS TLC.
20 years is maybe on the wire. It may have been already replaced.