Why a locked-on coil goes low resistance
A coil held on by a shorted driver overheats, its enamel burns and the turns short together, lowering resistance and adding heat until it is a near dead short under 2 ohms. Powering up with such a coil will kill a newly repaired driver the first time it fires.
Systems
Related tips
- A low resistance coil means checking its driver chain too
- Check every coil's resistance before first power-up
- Checking for voltage at a coil
- Testing a coil diode
- Low coil voltage from pitted L/R relay contacts
- What the coil diode does and how a bad one shows up
- Firing a coil by grounding its ground lug
- Re-measure the coil after replacing a shorted driver
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part One, Clay Harrell (pinrepair.com)