Half of the controlled insert lamps go out. The lamp driver transistors test good, and the dead lamps' transistors are not getting any drive signal.
Half the insert lamps out: open fuse under the playfield that tests good in its holder
Cause: One of the two lamp fuses under the playfield (each feeds half of the lamps, since the game drives its lamps in two phases) had failed open. It looked perfect and even showed continuity while in its holder, because the meter read back through the transformer winding.
Checks
- Remove each fuse from its holder before testing it; an in-circuit continuity reading can be false.
- Check the AC feed to the lamp fuses, including the violet transformer wires and their connector.
- Make sure the fuse holders grip tightly.
Fix
- Replace the open fuse with the correct rating.
Systems
Games
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Source: Pinball Repair help group!! (Facebook group)