MSX computer outputs B&W screen

[Midori]

I have a European MSX1 computer that I have been trying to swap the video processor in for it to output NTSC video instead, or PAL-60.

I have tried two things. The first thing was that I changed the TMS 9929 for a TMS9928. This swap gave me an output of a 60 Hz signal but incorrect colours, the colours were not swapped but not properly drawn on screen. All reds for example hade green vertical stripes in them.

I now opted for a TMS 9918 instead, I installed it and built this circuit: http://www.benheck.com/Games/Coleco/Video_Mod.htm

This gives me a Black and White image with strong vertical stripes in it.

Why? What am I doing wrong. Does anyone here have any experience with this kind of work? It seems like few others have tried to mod the MSX1 computers so I have very little information to go on.

I am trying to achieve a composite video output because my RGB mod for my second MSX is driving me to madness and I want to have at least onw usable MSX computer.