After a drop target reset coil burned, the playfield coil fuse (1 A) blows as soon as the replacement coil is connected, even after driver board repairs.
Drop target coil fuse keeps blowing: shorted diode on the coil
Cause: The diode on the coil itself was shorted. A miswired coil (power wire not on the banded end of the diode) blows the fuse the same way.
Checks
- Confirm the power wire goes to the banded end of the coil diode.
- With the coil disconnected the fuse should hold; then test the coil diode out of circuit with a meter.
Fix
- Replace the diode on the coil, keeping the band on the power side.
Systems
Games
Related tips
- Saucer fires at power-on and blows the playfield fuse: wrong coil killed its transistor
- Top lane gate never opens, even in solenoid test: failed driver transistor
- Coil in the drop target assembly is always on: burnt trace on the solenoid driver board
- Backbox GI out and fuse F6 blowing: burnt rectifier J3 plug and a shorted bridge
- No coils work at all though fuses are good and game starts: 43 V not reaching playfield
- Arcing between J3 pins on the solenoid driver board and displays out
- Pop bumpers and slings die minutes after a driver board swap: playfield fuse
- MPU gives 3 flashes after reassembly: two 15-pin plugs swapped
Source: Pinball Repair help group!! (Facebook group)