Entering the self-tests on System 4 to 7

Steps

• Let the game boot into attract mode and open the coin door.
• Flip the coin door auto/manual switch to its manual position and press Advance. System 4-6 displays go blank; System 7 shows all zeros.
• Set the switch back to auto-up. On System 4-6 press Advance once more.
• The first test cycles every display (credit/ball-in-play included) through 000000 to 999999.
• Each further Advance press moves on. System 7 then runs test 00 (sound); all versions then run 01 lamps (all CPU lamps flash together), 02 solenoids (coils 01-22 pulse in turn, number in the ball-in-play window), 03 switches and 04 audits.
• Leave the tests by switching the game off and on.

Systems

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

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