A flash lamp lights as soon as the game is switched on and stays lit; nearby plastics get hot or warp.

Flash lamp stuck on and melting plastics on L/R reversed games

Cause: A shorted multiplexed TIP122 on the CPU board. On these games the L-bank device is a flasher, which does not draw enough current to blow its fuse.

Checks

• With power off, test the TIP122 for that flasher from its metal tab to backbox ground; a beep means shorted.

Fix

• Switch off at once to save the plastics, then replace the transistor (TIP102) and its 2N4401 pre-driver.

Systems

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

Games

• Back to the Future
• Monday Night Football
• Phantom of the Opera
• Playboy 35th Anniversary
• Robocop
• The Simpsons
• Time Machine

Related tips

• A coil or flasher comes on and stays on at power-up
• Quick test for shorted TIP122/TIP102 drivers
• One or a few coils lock on at power-up
• Quick check of all TIP122/102 drivers before first power-on
• CPU and driver board transistors by position
• Solenoid driver test at 2J9 and 2J11 with Leon's code
• Diode-test the TIP120/TIP102 and 2N4401
• A coil has power but never fires

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