Your correct, the A500 doesn't have the required circuitry. I can't speak for the A1000, but I have done the S-Video hack for two A1200's and one A600 and all of those work great. A1200/600 has what's required, the signals are there. However a small circuit still had to be built (I guess to drive the signal or somthing) in order for it to work. The hack was copied from the CD32, which had S-Video built in.
I have also hacked an A520 Modulator to S-Video, which worked, but not very well for me. I think I might have an incorrect value resistor in there somewhere, I will figure it out one day. :-)
The reason I believe I made a mistake, is that I have seen somewhere on this or another forum, that other people have succesfully made the hack, and it works well.
