Testing the L/R select relay by grounding Q29

Steps

• Switch on and enter diagnostics, which should release the relay (after a game, a flasher show may keep it on for a while). With WWF Royal Rumble or a later game, shut the coin door.
• Clip one end of a jumper to the metal tab of CPU transistor Q29.
• Touch the other end to the backbox ground strap, or to the ground test point to the right of connector CN10 on the CPU board. The relay on the PPB board should click in, and drop out when you let go.
• Alternatively, ground the non-banded end of the 1N4004 diode beside the relay; that also pulls it in.
• Keep Q29 grounded only for a few minutes at most while you test the coils on the other bank.

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
• Under-playfield relay boards and the PPB board
• Firing a coil by grounding its TIP122/TIP102 tab
• All L or all R bank coils/flashers dead: PPB relay K1
• L/R relay burnt or intermittent
• Low coil voltage from pitted L/R relay contacts
• Flash lamp resistors on the PPB drop solenoid voltage for 12 V bulbs

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