You need a video cable with a 3W3 connector on one end. Original was likely a DEC BC29G-10. That, plus 5BNC-to-VGA cables, and 3 F/F BNC barrels, will work with a multisync monitor that handles sync-on-green.
I just went through this with several DECstations, where the Turbochannel graphics options have the same 3W3 connector. On Monday, May 3, 2021, 04:23:05 PM PDT, Adam Thornton via cctech <cct...@classiccmp.org> wrote: 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. Adam