Buying external SMD cables for Sun gear

[Tony Duell]

On Tue, Feb 25, 2020 at 4:20 PM Alan Perry via cctalk
<cctalk at classiccmp.org> wrote:
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> As previously discussed here, I have a Sun 3/260 that connects to a Sun external storage subsystem containing two 8” SMD drives. The external cabling is a 0.7m D-sub 25-pin (male both ends) data cable for each drive and a paired set of 0.7m D-sub 25- and 37-pin (male both ends) command cables. These cables are straight through connections between internal ribbon cables from the drives (CDC 9720-368 and Fujitsu M2372) to the controller board (Xylogics 451 on a VME adapter).
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> For reasons described below, I have been unable to buy the original Sun cables. Should off-the-shelf D-sub 25- and 37-pin cables work? I guess electrical shielding/noise could be a concern?

A lot of SMD cabling was that twist-n-flat ribbon cable, the twisted
pair stuff with flat sections to crimp IDC connectors onto. My guess
is that provided to arrange it so that the external cable twisted
pairs match up with the internal cable ones (or if the internal cables
are just plain ribbon cable, so that each twisted pair carries a
signal and its inverse (if you see what I mean) then it will work fine
with such cables.

I wouldn't try to use commercial DB25 and DC37 'round' cables as
there's no knowing what is going on inside the cable. But if you can
get some multiple twisted pair cable you could solder it to the right
connectors (again making sure a signal and its inverse end up on a
twisted pair). More work than the twist-n-flat cable though.

-tony