Test the sound board inputs one at a time

Steps

• Game off. Unplug sound board connector 10J3.
• Switch on. With a grounded test lead, touch 10J3 pins 2, 3, 4, 5 and 7 one at a time (pin 1 is the key).
• Each pin should give a different sound or speech clip.
• A pin with no sound (with good EPROMs) means a fault on the board's input side; try swapping the 6821 PIA (one from the driver board will do).
• If all five work here but sounds are missing in play, look at the driver board sound transistors (System 3-6) or the CPU board sound PIA at IC36 (System 7).

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Which sound board each game uses
• Sound board jumpers for 2K sound-only games
• Using the sound board test switch
• Powering a sound board for testing
• How System 3-6 games trigger sounds
• The sound board is its own computer
• Type 1 and type 2 sound boards and their switches
• Setting up a sound board for speech

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)