HP 9000-236 (9836CU) video cable.

[Tony Duell]

On Tue, May 22, 2018 at 5:56 PM, Robert via cctalk
<cctalk at classiccmp.org> wrote:
> My latest score is an HP 9836CU (so, color with a 68010 CPU and HP-UX
> support) with a 98625A disk interface. I got the matching monitor, but
> I didn't get the video cable.
>
> Googling turns up that it's a very proprietary interface, but I could
> find nothing about the cable. It's a 15 pin D-sub at each end and I'm
> hoping that it's just straight through, but have been unable to verify
> that.
>
> Does anybody know? Or Is there anybody that has a 9836C or CU and
> would be willing to examine the video cable, please?

The original cable has moulded connectors so I can't examine the
internal wiring.

It _is_ straight-through electrically, but there is a catch. There are 3
coaxial cables (and some plain wires) in there. The coaxial cables,
I guess 75 ohm characteristic impedance, carry the video signals.
They seem to be wired :

Red : centre to 12, shield to 13
Green : centre to 10, shield to 2
Blue : centre to 9, shield to 1.

The other pins are, as far as I know, plain wires. There is probably
an overall shield, grounded to pin 8

The pinout, AFAIK, is :
1 : Blue shield
2 : Green shield
3 : ground
4 : ground
5: N/C
6 : ground
7 : +12V (computer to monitor, to cause the latter to turn on)
8 : ground (overall shield?)

9 : Blue
10 : Green
11 : HSync
12 : Red
13 : Red shield
14 : VBlank
15 : VSync

Syncs and blanking are TTL levels, the video signal are current
(not voltage) levels, sourced by the monitor and sunk by the
computer.

-tony