Leon test: switch row inputs (2J3)

Steps

• With the Leon test EPROM running, ground 2J3 pin 9 (row 1).
• With the tester LED on +5 V, touch the PIA pin 2: it should flash.
• Then ground 2J3 pin 8 and look at PIA pin 3; carry on stepping down the connector and up the PIA.
• A step with no flash points to a bad PIA.

Systems

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

Related tips

• Switch matrix row test at 2J3 with Leon's code
• Test the switch PIA IC11 with the Leon test EPROM
• Switch matrix column test at 2J2 with Leon's code
• Switch column or row fault on the driver board
• Switches stuck on: board or playfield?
• Board or playfield? The switch test jumper method
• Logic-probe the switch matrix
• Switch matrix connector pins and their chips

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