That VAXStation4000vlc 3W3 video connector

[Peter Dreisiger]

> On 4 May 2021, at 19:00, cctalk-request at classiccmp.org wrote:
> 
> Message: 17
> Date: Mon, 3 May 2021 16:22:45 -0700
> From: Adam Thornton <athornton at gmail.com>
> To: "General Discussion: On-Topic Posts" <cctech at classiccmp.org>
> Subject: That VAXStation4000vlc 3W3 video connector
> Message-ID:
> 	<CAP2nic2zsyqsLo1dFTTPh4WFV6utS1Tt_4RMsROjsmw78+8zKQ at mail.gmail.com>
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> 
> I assume it would be way too much to hope that HD BNC would fit it?  Does
> anyone have a pointer to the actual physical dimensions of the itty-bitty
> BNC-ish connector in the video port of the VAXStation4000vlc?  If I can get
> red, green, and blue out (assuming since there are only 3 connectors it's
> sync-on-green) I can put together a sync splitter and turn it into VGA.  I
> have at least one decent multisync VGA monitor still, although none with
> the RGB BNC inputs.

Firstly, apologies if my response doesn't show up nicely in this thread --- I only receive the daily digests so I'm not sure how best to reply to a specific post...

But on the subject of sourcing / making video cables with 3W3 connectors on one end, I also balked at the cost of the coaxial insets and decided to make an only marginally dodgy (if I do say so myself) cable out of half of an old VGA cable, three of the 'sleeves' / female connectors contained, in abundance, in every female D-sub connector, and a few bits of heat-shrink (see https://media.decarchive.org/DEC/VAX/VAXstation%204000-VLC/IMG_3941.jpg for a photo of this cable from an albeit sub-optimal angle). The resulting connections were surprisingly stable, however, were I to make another one, I'd replace the grounding alligator clip with a lug that can be screwed onto one of retaining nuts next to the VLC's 3W3 connector, and use longer bits of heat-shrink to fully insulate the outside of the RGB connectors...

And just FYI, even as shown, the video quality was more than adequate (considering the resolution of the VLC's LCG framebuffer), however, I suppose one could always attach a shielded DA15 shell to provide a bit of extra noise suppression (as well as mechanical protection).


Hope this helps,

Peter