This is a view of the general Audio Amplifier section on the Namco PP board (Right side).
This board is actually the Video board.
The edge connector has pinouts for RGB signals only and Speaker output.

The 3-wire AMP connector (lower left) is for power only
Pin 1 = 12V,  Pin 2 = GND,  Pin 3 = 5V




There are 4 Audio Ampliers directly on-board. (bolted to the heatsink)
These replace the two found on each of the the two Atari ARII boards.



The ARII boards are very very sparse, providing only +5V to the main boards