Grounding Q29 does not make the L/R relay click, or the relay is energized all the time.

L/R relay never clicks: test Q29

Cause: Q29 is shorted, holding the relay on permanently.

Checks

• Power off. Set the meter to continuity, put one probe on the backbox ground strap and the other on Q29's metal tab. A dead short (beep, 0 ohms) means Q29 is bad.

Fix

• Replace Q29, then check that the relay has not been cooked by being held on.

Systems

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

Related tips

• The solenoid L/R select relay and transistor Q29
• Bank select relay and CPU transistor Q29
• Firing a coil by grounding its TIP122/TIP102 tab
• A coil has power but never fires
• A coil or flasher comes on and stays on at power-up
• Solenoid driver layout: 16 multiplexed plus 14 constant
• Multiplexed L/R (A/B) banks and wire colours
• Constant power coil drivers Q8-Q13 and Q23-Q30

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