(Topic ID: 253615)

Stern Star Trek Flipper Issue


By Thrillhouse

5 months ago



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  • 9 posts
  • 5 Pinsiders participating
  • Latest reply 5 months ago by Thrillhouse
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Diode (resized).JPG

#1 5 months ago

Hi,
In the middle of a game on my Star Trek (Original Stern release) I had fuse F5 (50V for Coils\flippers) on the power board blow. I powered the game off and took a look at the backbox and under the playfield and the fuse for the bottom right flipper was also blown. The switch actuator on the bottom right flipper had broken apart which I believe caused the initial problem since the EOS wasn't being opened. I replaced the fuses, crank, transistor Q16, and the coil also since the sleeve was melted to the inside but the resistance on the coil looked good. I checked and cleaned the EOS and flipper button contacts also. Upon powering it back up the right flipper would stutter and not hold in the up position. After a few flips I'm pretty sure it blew the transistor again because the coil locked on in the up position. Once the coil locked on I powered the game off to save the fuses. I've exhausted my level of know how at this point and was hoping for some advice on what to try next to get the game up and working again. Thanks in advance

#2 5 months ago

I'm not going to be any help with this, but I'll give you a free bump for the morning crowd.

#3 5 months ago

Have you checked the diode polarity on the new coil?

#4 5 months ago
Quoted from D-Gottlieb:

Have you checked the diode polarity on the new coil?

Stern coils, at least for the games I've messed with, don't use a diode.

Diode (resized).JPG

#5 5 months ago

Thanks guys. There is no diode on the coil but there maybe one on the board, if not a surface mount I'll see if I can find and check it

#6 5 months ago

Odd behavior for sure, while I don't suspect a failure of the flyback diode, I'm very interested in what you find.

#7 5 months ago

I had a coil stutter like that and blow a fuse on a much older game. It was a small short in the coil. Since you replaced the coil, it seems unlikely that a new one would be bad, but perhaps a stray bit of solder got in the wrong place and caused another short. I would hate for you to blow through another coil, but if you exhaust all other causes, you may want to try a third one.

#8 5 months ago

It was a guess. My TSPP has diodes everywhere as I recall but I don't remember on ST.

#9 5 months ago

Took the board to the local repair guru, he put a factory direct transistor in but no luck. Same thing happened, flipper would stutter and after 3 flips locked on again. Anyone else have any ideas or a referral to someone who works on SAM boards?

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