A lamp column stays dead or stuck after its TIP42 and the matrix resistors have been checked.
Lamp column still dead after a new TIP42
Cause: A fault further back in the column drive chain: the 2N6427 pre-drivers (Q56 to Q63), the 7408 chips at 9F and 10F, or the 6821 PIA at 11D.
Checks
- Test the 2N6427 for that column.
- Probe the 7408 outputs with a logic probe.
- Then suspect the PIA at 11D.
Fix
- Replace the failed pre-driver, gate chip or PIA.
Systems
Related tips
- A coil or flasher comes on and stays on at power-up
- How a coil or flasher is switched: PIA to TTL to pre-driver to driver
- Which logic chips drive which solenoid transistor pairs
- Damage after the black and white plugs were swapped
- Lamp and switch matrix transistor positions on the CPU board
- One switch column dead: parts to check in order
- Whole switch column dead after working under the playfield
- Switch column (drive) circuit on the CPU board
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)