Annoying EM Flipper chatter - What did I do wrong?

Rebuilt my Williams GP flippers and getting chatter in the hold position.

They have plenty of power to strike the ball and do not bounce when in hold. They just make a lot of noise and vibrate.

If I touch the plunger with my finger, the vibrations diminish. It's almost like there is too much play in the sleeve? Or something with the new stops? Range of motion is fine and nothing hangs, I can feel it reach the stop.

This is what I did - parts from Marcos:
- replaced EOS switches with new, adjusted and operating properly
- replaced sleeves
- replaced plunger & link - Flipper crank assembly - Williams left, A-8232-L
- replaced coil stop - Coil stop - Williams 3/8" centerline, A-6492
- replaced pf bushing
- added spring washer on plunger end of the coil
- 'squeezed' the coil bracket to tighten the coil a bit
- filed cabinet switches, there is plenty of contact

Did not do:
- Replace the coil, cleaned in and out, tabs and wiring look fine, power to thick wire side, cab switch on far tab with EOS
- Replace the spring, missed the order, but the old one does not bind on anything and appears to work fine
- Replace flippers, but in good working condition

Why are these damn things buzzing so bad? I've read Vid's threads and various other one, and can't figure out what I missed or need to do. Any suggestions are appreciated.

#2 4 years ago

edednedy

Pinside member

Cridersville, OH

10y 50,900 628 55

Are you sure that is the correct coil stop for an EM game?

#3 4 years ago

MDM

Black_Knight

It’s the only 3/8 centered screw stop listed on Marco and the pinball life one has the same specs.

If there is another one out there someone please let me know.

#4 4 years ago

edednedy

Pinside member

Cridersville, OH

10y 50,900 628 55

Pinball Resource

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#5 4 years ago

BMF

hawkeye11

Pinside member

Arvada, CO

14y 70,900 1,217 16 64

This is usually a broken hold winding on the flipper coil. Since their both doing it however, I would suspect the EOS switches. They might be gapped too close.

#6 4 years ago

MDM

Black_Knight

Ed- those look like the same I have, but will check with PBR to get the actual dimensions. Are these the ones you use?

Hawk - it’s not the EOS, they open several mm when open. If it was a bad winding, wouldn’t it not hold a ball well or hold when I push the flipper down. This isn’t a symptom, But I’ll swap another coil in to see what happens.

#7 4 years ago

edednedy

Pinside member

Cridersville, OH

10y 50,900 628 55

AC coil stops are slightly magnetic so that when the current alternates on and off 60 times a second, it doesn't completely let go, reducing the vibration.
I'm not sure if those stops are the right kind or not. Here's and old CARGPB trick. See if those coils stops are the same size as the stops on your credit unit. They should be, if they are, swap them. The credit unit coils didn't see near as much use and are usually in good shape. If the vibration reduces then you'll know it was the stops.

#8 4 years ago

MDM

Black_Knight

Thanks I’ll try that!

#9 4 years ago

JGI

John_I

Space Coast Pinball

19y 179K 9,069

Funny I just rebuilt the flippers on my Spanish Eyes and both were buzzing like mad no matter what I did. Finally I took a closer look at the new stops that came with the Pinball Resource rebuilt kit and they were the wrong ones! Fortunately a while back I ordered 4 of the correct coil stops (as pictured above by edednedy and still had two of them in my parts drawer. I put the flippers together one last time and made sure everything was good and tight and there is no buzz at all now!

#10 4 years ago

MDM

Black_Knight