Fixing a broken flipper on a Bally EM Pinball Machine

NOTE: There are high voltages under running around inside a pinball machine. BE CAREFUL! Unplug the machine when working on it.

Machine: 1974 Bally Sky Kings single player pinball machine

Problem: Right flipper doesn’t work. Makes a buzzing sound when flipper button is pressed. Coil looks toasted. Plunger doesn’t move freely inside the flipper coils.

Loud buzzing is probably coming from the plunger vibrating as it tries to move.

Right flipper making buzzing sound and not moving. Most likely coil overheated and melted the plastic flipper coil.

Looks like that flipper coils was getting stuck on – high power. Suspect and issue with the end of stroke switch. Most likely the plastic flipper coils inside melted and not the plunger is stuck!

That right flipper coils is looking rather crispy!

How Flippers on an Electromechanical Pinball Machine Work

Flippers on Electromechanical (EM) pinball machines are rather basic. The flipper button on the outside of the machine push in making the two switch leaves inside the machine make contact so that electricity can flow to the flipper coil.

When energized the flipper coils (basically a electro magnet) pulls the metal plunger inside. This is a very strong magnet using a lot of power.

Now if this flipper coils stays on for too long it will heat up. Eventually it will get so hot it will melt the plastic coil sleeve inside.

To keep this from happening there are two power settings on the coil. The first provides a burst of power that pulls the plunger and makes the flipper hit the heavy metal ball.

The second power level is just enough to keep the flipper in the up position. This uses a lot less power and can stay engaged without out melting the coil.

There is a EOS or end of stroke switch which cuts full power at the end of the stroke of flipper.

I suspect the full power was not being cut at the end of the flipper stroke. From the photo provided, one thing I noticed was the clear plastic insulation piece on the red wire. This is suppose to be between the two leafs of the EOS switch just to insure they are not touching.

If the leaves of the EOS switch are touching, then full power is going to the flipper coils and the power isn’t being cut at the end of the flipper stroke.

The flipper mechanism needs to be cutting power by opening up the switch at the end of the stroke.

More info: https://www.pinrepair.com/em/index3.htm#flips

PRO TIP: Look at the other flipper and see if everything looks the same.

Replacement Bally EM Flipper Coil for Sky Kings

Look on the schematics for the correct coil or get the information off the other coil. Keep in mind operators may have switched in different coils over the years. Might want to order two so they match. Should be 25-600-28-800?

The Pinball Resource will be cheaper but they have antiquated ordering system.

The Pinball Resource – https://www.pbresource.com/coilbly.html

Marco Specialities – https://www.marcospecialties.com/pinball-parts/AF-25-600_28-80

If you need more parts than the coil and coil sleeve, you can buy a rebuild kit (plunger, screws, stops etc) – https://www.pbresource.com/rebuildkit.html#KT-BFLIP01

So my trouble shooting advice would be as follows:

Compare the two flippers.
Look to see if the EOS switch is actually breaking contact. Examine the leaves and make sure they are not touching. Move the clear plastic insulation part down between the two leaves of the EOS switch.
The coil looks toasted. I’d order a new one. They come with a new coil sleeve (not always put in the right way when you get it).
Take lots of photos and label the wires so you know how it goes back together.
Put a white towel underneath the mechanism to catch any falling screws.
Take apart the metal parts holding in the coil and unsolder the wires.
Put the new coil in. Resolder the wires.