A group of coils or flash lamps on the shared drivers Q39-Q46 does not work, or the flashers fire when coils should (or the reverse).
Several bank-switched coils or flashers dead, or firing the wrong device
Cause: The L/R select relay is stuck on or off, or its driver Q29 is shorted so the relay sits on the R bank.
Checks
- Test the relay by grounding Q29 (see the L/R relay test).
- With power off, check Q29 tab to ground for a short.
Fix
- Replace a shorted Q29.
- Reflow the relay solder joints or replace the relay.
Systems
Related tips
- All L or all R bank coils/flashers dead: PPB relay K1
- L/R relay burnt or intermittent
- A coil or flasher comes on and stays on at power-up
- Only flash lamps work when a game starts (L/R reversed games)
- Use the manual's coil/flasher chart to find driver transistors
- Flash lamp stuck on and melting plastics on L/R reversed games
- Always check the coil diode when a driver transistor has failed
- Finding a coil's driver transistor without a manual
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Two, Clay Harrell (pinrepair.com)