A broken diode on a non-flipper coil often kills its driver
On coils other than flippers, a broken diode commonly shorts the driver transistor, so the coil locks on at power-up. Replacing the transistor without the diode leads to another short.
Systems
Related tips
- Always check the coil diode when a driver transistor has failed
- Testing a coil diode
- What the coil diode does and how a bad one shows up
- Re-measure the coil after replacing a shorted driver
- Measure every coil before powering up new driver transistors
- Finding a coil's driver transistor without a manual
- Fit a coil diode with its band on the power lug
- 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)