Mega Drive / Genesis problem

[didamangi]

I recently bought a 1st gen Mega Drive, I think it's the Asian PAL version. (Not sure)


Not exactly mint condition but it works alright except for one problem, it doesn't have any color.
I already try it in all PAL and both NTSC mode on my television but it's still doesn't show any color, just black and white.
This is with both the RF cable and the AV cable.

Any idea what's wrong, any of you guys ever had the same problem?
Thanks in advance.