The trough upkicker coil melted and blew fuse F6. A new coil wired the same way as the old one failed at once, and the drive transistor Q1 and its resistor R1 also burnt.
Trough upkicker blows F6 and cooks a new coil: its diode was the other way round
Cause: The new coil's diode faced the opposite way to the original, so with the old wiring the supply went to the wrong end of the diode. The diode failed and the transistor was left driving a short. A fast-blow fuse fitted where a slow-blow belongs may have added to the damage.
Checks
- Before powering a replacement coil, check the supply wire goes to the diode's banded end.
- Check the fuse type and rating against the manual.
Fix
- Replace Q1, R1 and the coil (or its diode), wire the coil so the supply is on the banded end, and fit the correct slow-blow fuse.
- Watch a newly fitted coil closely the first time it powers up.
Systems
Games
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Source: Pinball Repair help group!! (Facebook group)