Board or playfield? The switch test jumper method

Steps

• Put the game in switch test (test 03).
• Pull the two switch plugs at the top right of the driver board: 2J2 is columns, 2J3 rows.
• With a clip lead, connect 2J2 pin 1 to 2J3 pin 1, then to each other 2J3 pin in turn; each should report exactly one switch number.
• Move to the next 2J2 pin and repeat for all 64 combinations.
• More or less than one closure for a single jump means a driver board fault; if every jump reports correctly, the problem is on the playfield.

Systems

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

Related tips

• Switch column or row fault on the driver board
• Switches stuck on: board or playfield?
• Logic-probe the switch matrix
• Test the switch PIA IC11 with the Leon test EPROM
• Leon test: switch column drives (2J2)
• Leon test: switch row inputs (2J3)
• Driver board switch matrix resistors R204-R211
• Switches missed in a System 7 game with an older driver board

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