System 9: is the sound fault on the CPU board or the speech board?

Steps

• Unplug the large ribbon cable from the CPU board to the speech board.
• On the vertical male connector at the lower right of the CPU board, find the bottom pair of pins (toward the playfield) and fit a jumper on the pair just above them.
• Power up and run the sound test. If the CPU board sounds play (speech will not), the CPU sound section is fine and the speech board is suspect.
• If nothing plays, check the sound 6808, the sound 6821 PIA, the D/A converter and the amplifier. U11 and U17 are both 6808s and can be swapped to see if the fault moves.

Systems

• Williams System 9

Related tips

• Electronic spares worth keeping for System 11 boards
• System 11 switch matrix: connectors and chips
• Switch matrix dead after an under-playfield adjustment with power on
• No sound from a replacement sound board: its 6808 CPU socket was empty
• CPU chip types: 6800 on System 3/4, 6802 or 6808 on System 6/7
• CPU board PIA positions and jobs
• CPU still will not boot after the basics
• Switch column (drive) circuit on the CPU board

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell