Test each lamp row driver with a test lamp

Steps

• Remove the backglass, power up and start the "All" lamps test.
• Unplug CN6 and CN7 at the lower middle of the CPU board.
• Clip one lead of a borrowed 555 socket (with a working bulb) to CN7 pin 1 (right-hand pin as you face the board).
• Clip a second lead to the other socket lead with a 1N4004 on its free end, band facing away from the clip.
• Touch the banded end to CN6 pin 1, then each following CN6 pin.
• The bulb should flash on every row pin. No light or a steady bright light points to that row's TIP122/TIP102 transistor.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• How the CPU-controlled lamp matrix is wired
• Where the TIP122 drivers are on the CPU board
• Solenoid driver transistor positions on the CPU and PPB boards
• How a coil or flasher is switched: PIA to TTL to pre-driver to driver
• 50 V coils use PPB TIP36c transistors, pre-driven from the CPU board
• Multiplexed L/R (A/B) banks and wire colours
• Three-stage drive for 50 V coils
• The solenoid L/R select relay and transistor Q29

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)