PAL vs. NTSC on A1200

[Gulliver]

To make the A1200 NTSC you need to connect pin 41 of the Alice custom chip to ground, and that causes the A1200 to default to NTSC. If you are going to use the rf or composite outputs, you will need to change the built-in modulator, as NTSC signals have a different colour encoding system than PAL.
If you will only use the RGB port just do the pin ground mod and you will be set. Anyway, instead of changing the built-in modulator you can also attach an NTSC A520 external modulator.

I hope it helps.

[Gulliver]

The easiest way, if you are bad at soldering, is to get ground from the back of the power connector. But the most tidy, and adequate one, is making a tiny bridge with the ground signal present in the Alice chip itself.