Bally 6803: sound board boots but no sound in play: check the sound setting

On Bally 6803 games, a sound option of 0 turns the game sounds off, so the board boots and its test button works but nothing plays in a game or in sound test. Set it to 3 for full sound (2 gave effects without background). If settings look odd after the batteries died, the '65' factory reset clears them.