Well, its been a while, but Im back on the project.
Got distracted somehow...
But yesterday I dusted off my soldering Iron and started again.
Heres what I got so far.
I have a second Redant screen, it came with a PSOne so I could test it was working before I fried it.
Then I connected the old screen to the PSOne, and it worked.
So far so good.
Ill tried my luck again getting the SNES with RGB to work, but failed.
So I tried something else.
I took a SCART cable and connected the PSOne via RGB to my TV.
No picture.

So I tried SVideo with Y and C.
That worked.

Then I tried the SNES with the Redant screen vie SVideo Y and C.
Nothing.

I tried the SNES with SVideo on my TV.
That worked.
Then I tried my DVDplayer as Input for the Redant screen vie SVideo.
Nothing again.
So here are my conclusions:
Svideo Output from SNES works, SVideo Output from PSOne works.
Inputting SVideo (Y,C, GND) to the Redant Screen does not work.
I will try getting this damn RGB to work again.