System 9 and System 11 seven-segment LED codes
0: all tests passed (a 0 during the memory test instead means the blanking circuit is faulty). 1: CPU lock-up; look at the memory protect circuit and the U25 RAM. 2: the game EPROM at U27 has failed. 3: the game EPROM at U26 has failed. 4: not used. 5: blanking stuck; the coin door may be closed with a faulty memory protect circuit, or U25 is bad; open the door and retest (0 should appear). 7: no +12 V at the CPU, or bad or blank game EPROMs. 8: blanking circuit working (shown only during the memory test). Nothing shown: system failure; check +5 V or U26.
Systems
Games
Related tips
- Wrong coils fire and drop target dead: bad PIAs, shorted coil diode and Q14
- Which System 11 CPU boards fit which games
- System 9 CPU and sound test EPROMs
- System 9: Sorcerer uses two game EPROMs, Comet and Space Shuttle one
- No sound after board work: 1J15 and 1J16 swapped (they aren't keyed)
- Lizard eye flashers locked on, then not flashing: bad drive parts and a missing resistor
- Whole lamp column works only intermittently: reflow the board header
- Right sling locks on at power-up and a pop is dead: bad 7402 at U45
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)