With the centre and right targets of the three-bank down, rolling over the right return lane makes the game tilt.

Phantom tilt with two drops down: cold solder on a drop target switch diode

Cause: A diode on the centre drop target switch board had a cracked solder joint. The 3-bank series switch then read as closed, and together with the other closed switches it formed a loop in the switch matrix that the game read as the playfield tilt switch.

Checks

• In switch test, with all targets up and nothing on the playfield, press switches one at a time; any press that shows more than one switch number points at a shared row or column.
• Watch for the 3-bank series switch showing up when only two targets are down.
• Meter the drop target diodes (fine in circuit on open switches) and inspect every solder joint on the drop target switch boards; a joint can look fine and still be intermittent.

Fix

• Resolder the bad diode joint on the drop target switch board (or replace the switch board).

Systems

• Williams System 4

Games

• Flash

Related tips

• Drop target switches also trigger the eject hole: column jumper on wrong switch

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