When the game boots, a kickout saucer fires and the playfield solenoid fuse blows.

Saucer fires at power-on and blows the playfield fuse: wrong coil killed its transistor

Cause: Someone had fitted a coil of much lower resistance (about 4 ohms instead of about 13) on the saucer. It overloaded the driver transistor, which failed shorted and now holds the coil on.

Checks

• Measure every coil's resistance and compare with the manual; replace any wrong coil first.
• Test the driver transistors in diode mode; compare readings across all of them, as a shorted one reads much lower than normal.
• Check coil lugs are not touching metal and diodes are the right way round.

Fix

• Fit the correct coil, then replace the failed driver transistor for that saucer (Q13 for the side saucer on this game).
• Check the saucer switch wiring too; here a previous owner had wired its diode across the switch.

Systems

• Bally MPU AS-2518-35

Games

• Xenon

Related tips

• Drop target coil fuse keeps blowing: shorted diode on the coil
• Top lane gate never opens, even in solenoid test: failed driver transistor
• No coils work at all though fuses are good and game starts: 43 V not reaching playfield
• Coils go weak or the wrong coil fires mid-game: reseat the solenoid driver plugs
• Bally -35: momentary solenoids all dead but fire when grounded: solenoid driver U3
• Backbox GI out and fuse F6 blowing: burnt rectifier J3 plug and a shorted bridge
• Kickout coil burns up in attract mode: driver transistor, resistor and the CA3081 at U3
• Arcing between J3 pins on the solenoid driver board and displays out

Source: Pinball Repair help group!! (Facebook group)