All in all this is very simple. NTSC AGA machines differ from PAL ones in these ways:
PSU: 110V vs 220V: easily exchanged/adapted
Alice: the very same, just the JUMPER/solder bridge for pin 41 (_NTSC/PAL) differs
modulator: different part, must be exchanged if composite is needed. RGB doesn't care.
oscillator: differs slightly, but doesn't really matter (if you're not genlocking or using an A2024)
All RGB monitors I've ever seen (1081, various 1084, Philips, Profex, ...) can be adjusted (vertical sync & height) to either PAL or NTSC.
PS: _NTSC comes out of the U12 encoder and runs through Q201 (all between IDE and PCMCIA). Probably that's a different part, too, but my schematics are too bad to read...
PPS: no I have it I think: the _NTSC doesn't come from the encoder - that one just needs the inverted signal. So R203 (0 Ohms) decides whether NTSC (present) or PAL (missing). Can anyone with a PAL 1200 confirm that it's missing?
