Quick test for shorted TIP122/TIP102 drivers

Steps

• Make sure the game is switched off.
• Set the meter to continuity (beep).
• Clip one probe to the backbox ground strap.
• Touch the second probe to the metal tab of each TIP122/TIP102 on the CPU board.
• A beep (zero ohms) means that transistor is shorted.
• Replace any shorted one with a TIP102, and also its 2N4401 pre-driver, before powering up.

Systems

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

Related tips

• Flash lamp stuck on and melting plastics on L/R reversed games
• A coil or flasher comes on and stays on at power-up
• Quick check of all TIP122/102 drivers before first power-on
• Replace failed TIP122 drivers with TIP102
• CPU and driver board transistors by position
• Diode-test the TIP120/TIP102 and 2N4401
• Solenoid driver test at 2J9 and 2J11 with Leon's code
• One or a few coils lock on at power-up

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