What's this little guy do, and why is he on fire?

rookie123

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1992 SMB Gottlieb Pin, right flipper suddenly went to up position during game play and stayed there, goes back down as soon as ball gets past flipper and no balls are in play. First thing I checked was the fuse, its good, but when I opened up under the playfield I smelled and saw smoke coming from this little round guy next to the flipper button, obviously this is a problem, and now he is too burnt to figure out the part #. Wondering if you experts know what it is, and also if you think its my only problem or if there is some other bigger issue. Thanks guys.
 

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Hmmm, looks like someone thought a capacitor and a diode were interchangeable...

That's a flipper button leaf which is normal to have a cap on it.
Are you sure it's on fire or is that good old fashioned dust/dirt on it?
 
Oh no, definitely on fire, smoke visualized, and plastic melting, dripping to inside floor of pin.
 
Interesting. What kind of voltage is running through that circuit? Is that one advantage of using optos in more modern machines? To reduce the likelihood of fire?

There is a big spark suppressing cap on the flipper coil. I'm not convinced that the cap on the switch is not to debounce the switch closure going to the optocoupler that tells the MPU the flipper button has been pressed but I don't have the schematic available right now so I can't say for sure. If it is being used for spark suppression it's definitely working in tandem with the one on the coil and this problem could actually be caused by that cap going open now that I'm thinking about it. That small cap on the switch looks way too small to me to do any effective spark suppression. I have been wrong before :)
 
Interesting. What kind of voltage is running through that circuit? Is that one advantage of using optos in more modern machines? To reduce the likelihood of fire?

Full flipper coil voltage and current. Gottlieb did NOT use solid state flippers, like Williams and the others. This system is old-school flipper circuit with high current switches directly powering the flipper coils.

Gottlieb kept this system for no other reason than it was cheap (IMHO)

The use of opto's and other low current circuits in solid state flipper systems found in Williams, and others, machines, has more to do with longevity and reliabilty instead of fire proofing. By moving away from high current switches, switch wear and pitting that caused weak flippers was eliminated. Additionally, the use of opto's removed switch adjustment problems. Solid state flipper systems reduced coil failures due to EOS switch problems and helped ensure longer, more consistant, flipper operation.
 
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that is a veristor, its function is as a surge protector

while you can just remove it, there is a reason it burned up

so most likely there is a bad cap
 
that is a veristor, its function is as a surge protector

while you can just remove it, there is a reason it burned up

so most likely there is a bad cap

You're right... it is a varistor. I though that when I looked at it but my brain said "can't be". I looked at the schematic and that's exactly what it is. Stupid brain.
 
You're right... it is a varistor. I though that when I looked at it but my brain said "can't be". I looked at the schematic and that's exactly what it is. Stupid brain.

even einstein had issues :)

i only know this because my maverick wouldnt do anything when i got it

the emi filter had a burnt veristor!, i could've just removed it, but i REPLACED it,

all is now well


im no expert on gottlieb, but imo i would replace both the bad cap and veristor
 
You guys are awesome. Lindsey, you were totally correct, cutting it out made the flipper work perfectly, just got to go track down a new one, thanks everyone for your help on this.
 
haha! Well... I gave you your due credit. If that makes you feel any better. You were right and I was wrong. From me that's about the best compliment you're ever going to get. And a rare one at that. :)

lol i know, i was being a smartass , did feel good to be right though lol :)
 
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