dm800se clone video out problem

pls fellow satmates my dm800se clone having problem with scart. the hdmi works great but the scart is giving me problems.when i switch it on bootlogo dont display no matter the type of image. the second bootlogo appears but its very dim and if care is not taken, you might not see it. the final logo that acts as a wallpaper appears but the screen is not stable with zigzag pictures. sometimes the screen is divided with the bottom rather at the top. i have changed images, tvs, scart cable and av settings but no show.
In av settings, i only get picture when i select scart, and RGB. when i change from RGB to CBVS OR YBVR , THE screen goes blank. when i switch from scart to hdmi or hdmi-pc, the screen also goes blank. pls help.