(Topic ID: 65571)

14 ohms on my flipper coil, what does that mean?

By Piparoo

10 years ago


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#1 10 years ago

I've been restoring a DE Tales from the Crypt and the upper right flipper has never worked. Yesterday I rebuilt the flippers, replacing everything but the coil. It's still not working. I pulled out my multimeter and the flipper that isn't working is registering a resistance of 14 something ohms. The other two flippers are right around 3.7-4.3 ohms. Can anyone tell me where to start looking for the issue? Is it just a bad coil?

#2 10 years ago

Ya. Replace the coil. That's way too much resistance.

#3 10 years ago

It looks like the upper flipper coil is supposed to have 14 ohms resistance. According to DE the correct coil is 090-5041, with a resistance of 13.8 ohms. Guess my next step is to check the flipper boards.

#4 10 years ago

Fortunately, the SSFB has an LED for each flipper that should light when the cabinet flipper button is pressed. Check that out first. If no LED, the signal path from cab switch to the SSFB has been. severed.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#5 10 years ago

Thanks Chris. I'm also wondering if it might just be the upper flipper switch failing to make contact at the flipper button

#6 10 years ago

Yup, dirty contacts at the flipper button switch. Sometimes it really is the simple solution.

#7 10 years ago

14 ohms still seems high when the manual says that all three coils should be the same...

viperrwk

#8 10 years ago

You're right about the manual. Later service bulletin from DE, which enumerates all of the coil part numbers for DE machines, indicates a different coil on the upper flipper, the 14 ohm 090-5041. Tis a bit weird.

#9 10 years ago

I can believe 14 ohms since the longest shot with that flipper is about 12 inches to the tombstone. A stronger coil might break things.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#10 10 years ago

Probably lowered it because the higher strength coil was causing damage. Good to know and thanks for the follow-up.

Edit just saw Chris' post. Never mind...

viperrwk

#11 10 years ago

A coil is just what it sounds like. A coiled-up length of wire with ultra-thin insulation. They don't "go bad" in the sense of other components. They either work or they don't. The only time a coil will malfunction solely due to the coil itself is if there is a short somewhere in the coil winding. Otherwise, it's due to your connections or something else in the machine. If the coil reads 14 Ohms, then it's a 14 Ohm coil. A short would not change the resistance inherent to the wire.

#12 10 years ago
Quoted from JoJoBear:

A coil is just what it sounds like. A coiled-up length of wire with ultra-thin insulation. ... ...A short would not change the resistance inherent to the wire.

...Unless, the short is between two or more of the coils windings. Then the short effectively "shortens" the length of wire, reducing the resistance, and increasing the magnetic field strength on the core (plunger). This is true up to the point where the coil becomes more of a zero ohm direct short with nearly no resistance, and no magnetic lines of flux at all.

--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#13 10 years ago

I'll admit to being a greenhorn when it comes to a lot of this stuff. I measured the resistance because it was suggested as one of the things to check when troubleshooting. I think I read it in clay's guide. But you're right, I was really expecting to see a lower resistance than 3.5 or so ohms on the bad flipper. That's why the higher number was so confusing. Everyone's explanation has been helpful in sorting it out though.

#14 10 years ago
Quoted from Piparoo:

I measured the resistance because it was suggested as one of the things to check when troubleshooting.

Absolutely the right first step. You are off to a great start!
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

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