If you mind to hack your A1200, simply open it, and then make the following hack:
Locate the CXA1145 (CXA1645 is an equivalent with the exactly same pinout) chip on the board, middle way of power connector and PCMCIA, put two wires (shielded ones are better) on pins luma (Y) and chroma (C) and route them to a S_VHS female connector. Ground must be taken from somewhere inside the case too (not from shield!). Remember to ground only one side the shielded cables to avoid parasite currents and ground loops (who will ruin the hack).
OK, pure RGB gives a sharper picture, but S-VHS is way better than composite.
You only needs the pinouts of the chip and S-VHS connector. And Google is your friend! ;-)
