Test the driver board PIAs IC5, IC10 and IC11 with Leon's code

Steps

• Remove fuses F1, F2 and F3 if the boards are in the game; take +5 V for the tester LED from interboard pin 1.
• The driver PIAs run left to right: IC5 solenoids, IC10 lamp matrix, IC11 switch matrix.
• Before testing IC11 pins 2-9, ground every pin of connector 2J3 (a shorting plug helps); otherwise those pins will not toggle.
• On each PIA, pins 2-17 should blink about once a second; pins 19 and 39 may not; data pins 26-33 should pulse on a logic probe; pin 34 should be high.
• Any of pins 2-17 not blinking: replace that PIA with a socketed 6821. Interboard pin 37 (blanking) should be high.

Remove F1 (display high voltage) before probing boards in the game.

Systems

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

Related tips

• Test the switch PIA IC11 with the Leon test EPROM
• Damage after the black and white plugs were swapped
• Displays show only every other digit ("0_0_0")
• Test the CPU board PIA IC18 with Leon's code
• Leon code running but LEDs dark: bad CPU PIA IC18
• How a coil or flasher is switched: PIA to TTL to pre-driver to driver
• CPU board PIA positions and jobs
• Test EPROM flash codes: which chip failed

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