6128 scart to composite, component, vga or what (on a projector)?

[Bryce]

To fix the problems you're having with the picture add the 75ohm resistor as Zuse suggests. If it's still giving a dodgy picture after that, then check that the GND of the CPC and the MP2 are properly connected, you can also add a capacitor (about 220µf) in series with the signal to improve the quality.

Bryce.