Which lines from the logic board harness are you connecting to what & where? A diagram of your hookup would be most helpful in troubleshooting.
There's an ancient setup for building the CatMac/Hickintosh floating around, checking against that would be my first step. There have been fairly recent threads about doing this here and there. It was for hooking up to a composite monitor back then. You go from there to VGA these days, but that seems overkill.
It would seem to me that you'd want to tie your two analog B&W lines directly to RG&B on the "VGA" HD15 connector along with ground as I did for the Radius TPD Card.
I'll see if this makes any sense after caffeine deprivation subsides.
edit: some but not a lot of sense it seems. Have you got the rest of the Mac reassemble with Logic Board and A/B for testing just the VidCard with the CRT up and running for troubleshooting? Start testing from ground level.
That still looks like way too many wires and connectors, which introduce capacitance in your circuit, ISTR?
Quick question, why is the VidCard not plugged into the PDS in that shot?