I found the CD32 schematic, and the circuit is more complicated than I expected. The transistors look like they are buffers for the signal, which could mean that the Sony chip cannot source much current.
I would try connecting a 100uF capacitor and 75-ohm resistor in series, along with a 100pF capacitor connected to ground. This is the part of the circuit to the right of the transistors, from what I can tell (the image is not very clear). Trying to make the adapter I made for PAL use is much more complicated than this. I made it for my A500 and A1000 which don't have this type of circuitry.
Has anybody else here made this mod to their A1200?
EDIT: My adaptor is based on the Neobitz adaptor, which is also NTSC only. However, if you order that kit, it would be easy to modify the board for PAL use. Just change the crystal to one with the correct PAL frequency, and change the logic level on the STND line.