Howdy-

I'm troubleshooting a Wizard of Oz ECLE that was working fine, was moved to a new location, & then developed a problem.

1 - Both mini PF flippers & all 3 slings not firing in gameplay or test.

2 - Found fuse F708 blown (250V 5A, time delay), which corresponds to J108 on I/O PCB, which matches these coils. Why blown, I wonder?

3 - Put in a 250V 4A fuse (all I had on hand).

4 - Entered self-test. All those coils now working, except for right sling.

5 - Checked continuity of wiring, checked for shorts, checked coil resistances. All seem OK.

6 - Powered down, unplugged wiring harness from J108 on I/O PCB, swapped harness connector pins for left & right slings to see if the broken coil "moved" or stayed put, plugged back in.

7 - Powered up, tested. Now the right sling works & the left doesn't. This tells me that the wiring & coil are OK & that the problem is on the PCB.

8 - Diode D403 checks out OK. Therefore, I suspect MOSFET Q403 (P/N 130-0000-0T: MOSFET, IRL540, N-Ch, TO-220AB, 100V, 36A).

Before I track down the MOSFET, order it, pull the PCB, & swap it out, does anybody have any input on my troubleshooting or any similar experience that suggests I should try another path?

Thank you,
-Jason

Thanks for the feedback.

Found I had 1 MOSFET from a previous machine. Got ready to pull the board & swap the MOSFET. Wanted to do 1 final test to double-check that I had the right component targeted before I dove in.

Plugged the J108 connector back into the PCB. Powered up, tested coils. ALL WORKED! The only thing that I changed was disconnecting & reconnecting that connector. I looked in at the pins in the harness Molex connector. Pin 7, Munchkinland Flipper Hold, was rather bent & might not have been making good contact w/ the PCB header, so I removed it, bent it, & re-inserted it, but that wasn't the problematic coil anyway... :\

Mixed feelings. Glad it's working, but suspicious of self-fixing. Played a few games (w/ my 4A fuse still in there). Played fine.

2 items of note:
- I found a 250V 6.3A fuse, unblown, next to the I/O PCB. I don't know if it's possible that it was under the I/O PCB & shorting the right sling pin--it was in the same general vicinity..
- Right sling seems to double-activate. Other slings just go "bang!", while the right sling goes "ba-bang!"; it has a slight rattle/rebound/double-activation. It seems to play fine, though. Perhaps a nit-pick, perhaps a clue or culprit?

Thanks,
-Jason

Reflowed the solder on right sling coil lugs, didn't find any flaws in the magnet wire on the coil.

Went into test mode & kept firing the right sling while applying pressure to the coil wires to see if there was a tenuous connection. Behaved fine.

Difficult to tell if I'm getting switch bounce for multiple right sling coil actuations. Opened up the gaps in the right sling's switches a hair more. Subjectively looks/feels/sounds like the left sling now.

All seems well. I'm satisfied. Chalk it up to a little weirdness from moving a game(?)

Thanks for all of your inputs.
-Jason

Howdy-

Thanks for the compliment. The game has been pretty much 100% problem-free after having a few post-move gremlins (backbox translite LED strip connector pin pushed out & made intermittent contact, had some weird boot problem that fixed itself on the next boot, lights got "stuck" once or twice, game froze once or twice).

I'm not convinced that I did anything significant to remedy my problem--might have just been a connector that needed reseating to make good contact(?)

Good luck,
-Jason