(Topic ID: 304732)

Fuse F118 blowing on coil fire: NBAFB

By SimpleSkin

5 months ago

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  • 21 posts
  • 5 Pinsiders participating
  • Latest reply 12 days ago by SimpleSkin
  • Topic is favorited by 1 Pinsider


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#1 5 months ago

All of a sudden a my shoot 1 and shoot 2 coils stopped working in Fastbreak. These are for shooting the basket in position 1 and 2. They share a common wire red/vio. I traced it to a blown F118 fuse. If I replace the fuse it immediately blows again when either of those 2 coils attempt to fire. I removed the connector supplying power to the coils and when I run the coil test the fuse doesn't blow. I assume this means the board is ok and it's a problem with one of the coils or wiring. I can find no shorts or cut wiring or anything wrong with the wiring to those two coils.

Any ideas what to try next?

#3 5 months ago
Quoted from LTG:

Disconnect one of the coils and try. If it blows that is the bad coil, if not, it's the other coil.
Check that their lugs aren't close to metal of any kind.
LTG : )

Thanks for the tip. I just got around to working on this again this morning after Thanksgiving. If I disconnect the Shoot 1 coil. The fuse blows and Shoot 1 and 2 don't fire. If I disconnect Shoot 2 the fuse doesn't blow and Shoot 1 fires.

Does this mean the Shoot 2 coil is bad and should be replaced? I can see nothing wrong with the wiring of that coil or metal near the tabs.

Thank you.

#5 5 months ago
Quoted from LTG:

I'd start there.

Coils ordered. I'll report back in a few days.

Thanks again.

#6 5 months ago

My new coil will be arriving later today. In anticipation I opened up the cabinet and decided check the suspect coil with my multimeter. All four of the shoot coils measure the same 3.9 ohms. Does that mean that the coil is not shorted?


#7 5 months ago

I replaced the coil and it still blows the fuse. Not sure what else to check for or test at this point.

#9 5 months ago
Quoted from phishrace:

You need to test the transistors associated with those coils. Manual will tell you which transistor goes with each coil.

I pulled the board and tested both the TIP-102 and TIP-36c transistors associated with the Shoot 1 and Shoot 2 coils. The TIP-102 at location Q86 is showing continuity or bad. I'm guessing I should replace this transistor as my next move? Love Marco . I only need $2.29 part and it will cost me $9.99 shipping. I'll have to throw a bunch of other random spares into my order including more of both of these transistors.

#12 5 months ago
Quoted from phishrace:

You guessed right. You also want to double check the new coils (resistance) and any diodes on the coils. Don't think those coils call for diodes, but if they do, test them. Shorted transistors sometimes destroy diodes.

Yep. No diodes on those coils. I will test the coils as well. By the way, I'm guessing you are a Phish fan. I caught both of the Hershey Park shows this summer!

#13 5 months ago

I'm happy to report that I have fixed my Fastbreak. I ended up replacing both the TIP102 and TIP36 C associated with the affected coil and fuse. Machine is playing great after being down for over week.

Everyone of you was instrumental in troubleshooting and offering the solutions.

Thank you!

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#14 5 months ago

Looks like I got ahead of myself. Everything worked perfectly for 10 games or so and then the Shoot 1 and 2 coils stopped working. Blown fuse again at F118. Quick test of the replaced transistors shows that they were ok. Any ideas?

The saga continues.


1 month later
#15 4 months ago

So I'm still stuck on this problem. Something is frying the transistors associated with shoot 2 coil. After the above repairs fixed my problem the problem came back after a few games. I pulled the power board and tested the transistors and the TIP102 was again dead. I replaced that transistor and swapped the board into my NGG. NGG plays fine and doesn't blow the fuse.

I put the board back into FB and ran the coil tests on shoot 2. The coil fired 20 times or so then started buzzing. I immediately turned off the machine and the fuse was blown. The quick test on the TIP102 says it's still good. I will pull the board later today and do the full test of that transistor by placing the probes on the legs and measuring.

I've used my DMM to test the wiring from the board to the coil and from the jumper to the coil and it doesn't seem like there is a short in the wiring between the board and the coil.

Not sure if this additional info is useful to anyone here who may have an idea of what to try next. I am at my wits end and with this machine.


#17 4 months ago
Quoted from zaza:

Did you check diode D88 on the powerdriver ?
NGG uses this for the "flipper hold" and has a diode on the coil.
NBA:FB uses this for a coil without installed diode.
When diode D88 has failed, transistor Q86 will eventually blow

I couldn't find a diode labeled D88 but if it's the one directly to the left of Q86 then it's reading .532 which is think is normal?


#19 4 months ago
Quoted from zaza:

Yes and yes.

Any other ideas? I was hoping this was the culprit.


4 months later
#21 12 days ago

So it turns out it was the power driver board. I built two different test harnesses to rule out the wiring or the coils. One of the harnesses I built was wired directly from the board to the coil and I was able to still blow the fuse. Swapped out the original board for a new Rottendog board and all is well. Sending the original board out for repair. Now I'll have an extra board for testing or as a backup. Can't believe I can finally play again.

Now NGG needs a little love.


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