The coil fires with its ground lug jumpered, but not when its driver's tab is grounded.
Coil fires when grounded at the coil but not from the transistor tab
Cause: The fault is in the wire or connector between the board and the coil, most often a broken wire or a poor connector pin. A bad driver or pre-driver is also possible.
Checks
- Check continuity from the coil ground lug to the board connector pin.
- Diode-test the driver and pre-driver.
Fix
- Repair the wire or repin the connector.
Systems
Related tips
- Random glitches in play (DMD freezes, odd awards): reseat the ribbon cables
- Coil passes every test but still will not work in play
- Always check the coil diode when a driver transistor has failed
- Finding a coil's driver transistor without a manual
- Quick lamp row check: ground the row transistor tab
- Use the manual's coil/flasher chart to find driver transistors
- Solenoid driver transistor positions on the CPU and PPB boards
- 50 V coils use PPB TIP36c transistors, pre-driven from the CPU board
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Two, Clay Harrell (pinrepair.com)