Quick sound checks by grounding

Steps

• Briefly ground a sound select pin on the sound board to play some (not all) sounds; the sound board test switch plays most of them.
• On System 3-6, with the game on, ground the metal tab of each sound driver transistor (coils 9-13, Q31, Q33, Q35, Q37, Q39, lower left of the driver board) to check the path to the sound board.
• Check those TIP transistors for leads broken by board handling, and connector 2J9 for cracked joints.

Systems

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

Related tips

• No sound in play or solenoid test, and grounding inputs does nothing
• Which sound board each game uses
• 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
• Sound board completely dead

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