(Topic ID: 69322)

Best Way to Track Down Short in GI Lighting?

By Whitebuffalo

7 years ago

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  • 18 posts
  • 12 Pinsiders participating
  • Latest reply 4 years ago by Lermods
  • Topic is favorited by 21 Pinsiders


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#1 7 years ago

I've got a Gottlieb Devil's Dare that has a short somewhere's in the playfield GI lighting. At least that is what I think, but am not sure. The backbox GI is fine. Playfield GI was working fine for a little while, but now it just blows the fuse every time I plug a new one in after changing things around. It has some loose wires, but from what I can see nothing is touching. I really don't know where to start! Any help would be great!

#3 7 years ago

This is from RGP - Mark Clayton - I've done it on EMs FWIW

Take one of your blown fuses, and using some short wires
solder a 44 or 47 light bulb across it. Now install
it in the place where your fuse is blowing. All the
lights will be dim, but when the short happens again,
the bulb across the fuse will light up fully. Now you
can wiggle things and fiddle around until you find the
short, and you won't blow any more fuses.

Forgot to mention, after installing the bulb - un-solder sections of the GI string until the short disappears.

#4 7 years ago

Check continuity between Gi lights with a multimeter. Power off obviously.

#5 7 years ago

Thanks for the tips I'll try both of them today.

#6 7 years ago

Ahh just had this problem on a Space Shuttle. One of the most frustrating times. First you have to determine the short. Test continuity from back box to GI. If all of that is good, check your bulbs. It is possible to get a bad bulb that causes a short (unlikely but possible). Next look for any wires touching underneath the playfield (this is the most likely scenario). Especially pay attention to the staples that hold in GI. It is possible that it is touching the socket body. Make sure to also check for metal shavings or solder that could have made their way to the sockets. Last case scenario and what was wrong with mine was a bad light socket. I sectioned off certain section of GI into smaller sections by disconnecting from game and unsoldering sections. I then checked the Ohms with a multimeter in the lowest setting. Test the light sockets themselves on the tabs on the bottom, this will check the entire section. If that section was good, it would read NL. If there was a short in that section, it would read a number (0.01 to whatever). Then you had to unsolder each socket in the bad section until you found the light socket that was bad. It worked for me just a lot of soldering and unsoldering.

#7 7 years ago

Funny, I have a DD and while trying to fix the issue with my ball save issue, I have no blown fuses, but NONE of my playfield lights that illuminate the field work....all the ones in the PF work fine....strange, but true...

#8 7 years ago
Quoted from 1452spunky:

Funny, I have a DD and while trying to fix the issue with my ball save issue, I have no blown fuses, but NONE of my playfield lights that illuminate the field work....all the ones in the PF work fine....strange, but true...

The curse of Devil's Dare!

#9 7 years ago

Hahahaha, but WE have the BEST machine for the money available out there, IMHO....everyone that plays it loves it !!

#10 7 years ago

Excellent commentary, Jared!!!

#11 7 years ago

Most GI bulbs should measure between 3 ohm and 5 ohm resistance. If the string is shorted, it will usually read 1 or 2 ohm... If it's 1, the fuse will blow very quickly. If 2ish, it will sometimes take a few seconds to blow and the lights will be VERY bright for those few seconds.

I had this happen on my Harlem and Bow and Arrow. In both cases, it was a bad "shorted closed" bulb. In order to determine this, I removed every bulb in the string and just replaced them with new. Neither have ever shorted again. Your mileage may vary but if it's easy to pull all the bulbs, (you can sometimes remove GI from under the playfield much quicker) it may be worth trying to see if the short is still there. You may also have to desolder the GI wires at the source of the string.

You mileage may vary but hopefully something here helps clarify things.

#12 7 years ago

I have also had a shorted bulb right out of a brand new package. It does happen!

#13 7 years ago

I'm thinking it is a shorted bulb because I had just replaced almost all the ones in the GI.

#14 7 years ago

Follow what Snyper said then. Do yourself a favor and get aerosol keyboard cleaner and spray the sockets while you are pulling out the bulbs. It is possible you knocked something in while changing bulbs.

1 year later
#15 5 years ago

Bump to save this very helpful thread.

8 months later
#16 4 years ago

Thanks Mr Clayton


7 months later
#17 4 years ago

This is some great information !! My Playfield GI is dead shorted and blowing a fuse as soon as you put one in on my Gottlieb Fast Draw !! It has been driving me nuts !! Now to start the trouble shooting !! Thank you !!!!

#18 4 years ago

Use a 9v battery, hook alligator clips to it, then with the game off touch the clips to a socket. See which bulb in the string doesn't light and youve found your problem.

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