A replacement coil (here the ramp diverter) cooks and bubbles shortly after being fitted, though the owner never noticed it locked on. The old coil had burned too.
Brand-new coil burns up soon after fitting: find the reason the old one burned
Cause: The driver transistor for that coil was faulty, so the coil was being held on; the replacement coil was also bad.
Checks
- With power off, test the coil's driver transistor in diode mode against its neighbours, both directions on every pair of legs, with the board's plugs removed.
- With a lead of the coil lifted, power on and check for voltage between the coil wires; if the circuit is driving, work back through the pre-driver and logic chip.
- Check the coil is not touching a nearby post or bracket through a worn paper wrapper.
Fix
- Replace the faulty driver transistor and fit another new coil.
Systems
Games
Related tips
- F103 blows instantly: shorted ramp diverter coil; magnet fires the diverter if F104 open
- A coil stays energized
- A coil burned up
- Two or more coils fire together
- A coil does nothing although its fuse is good
- Flasher glows full bright until the bulb blows: shorted driver transistor
- Coil-not-working checklist
- One coil will not fire
Source: Pinball Repair help group!! (Facebook group)