Vectorman, on Wed Aug 5, 2009 8:12 PM, said:
The A/V mod I did on mine years ago was tapped directly from the audio/video chips. I didn't go inside the rf module like some people do. You do need some other parts( resistors/capacitors) in between to get the signal levels right.
The daughter board contains a chip which converts the color difference signals off the TMS9928 to composite.
The TMS9918 chip is identical but puts out composite natively instead of using a color diff output.
If you want to skip the RF board, the easiest way to do so would be to find a TMS9918A chip on eBay, clip pins 35 and 37 off completely (don't connect them to the board), and bend pin 36 up and to the side instead of setting it in the board.
Tie Pin 36 to ground by way of a 470 ohm resistor. At this point, pin 36 itself will then supply a great composite signal. You don't even have to run it through DC removal or impedance matching as its all in the chip.
This produces a great signal. But you'll lose video and audio from the Atari 2600 expansion module.
Good luck.
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