> On Feb 14, 2020, at 4:54 PM, jim stephens via cctalk <cctalk@classiccmp.org>
> wrote:
>
> ...
> The SCSI spec and cabling have a specific way that the conductors have to be
> rolled to make a round cable. Each cable type has a recommended way that
> signal and grounds should be paired and in what proximity in the cable.
>
> For SMD I never saw a formal spec with as much detail as the SCSI spec, and I
> don't know if they standardized the cabling. Mainly to speculate about
> whether you can use a generic 25-25 or 37-37 straight thru.
>
> I suspect the 25-25 would be sensitive to the type of conductor pairing and
> fabrication would work.
That reminds me of a situation I ran into about 20 years ago, working for a
small router company. They had a long spool of Ethernet cable to verify
correct operation with max length cables. But things were not working right.
At some point I inspected the connectors and noticed the pairs were connected
to pins 1-2, 3-4, 5-6, 7-8. So two of the Ethernet pairs were split, since the
correct pairing is 1-2, 3-6, 4-5, 7-8. I cut off the connectors and described
the correct way; once new connectors were put on correctly the tests passed.
paul
