I think that your card requires a SoG compatible monitor, like a Dell 1907FP.

Or maybe the adapter is not compatible, is it one of those models with a few DIP switches on it?

It's been a while since I heard from this. Any luck?

For the card to work, the monitor should do 640X480 256 colors with Horz & Vert Sync on and Composite Video on in the adapter you are using. I find that if you set it to work with a LC/LC II, it should work with the Mac II Video Cards.

EDIT: Also - check the caps on the Video Board. They need to be recapped too if they are as old as the IIcx.