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Pinball Rehab

pinball repair and restoration

Rebuilding Flippers Rebuilding Flippers Featured Hot

Most games haven't had the flippers rebuilt in years and yet it's one of the easiest ways to improve game play.  In most cases two flipper rebuild kits will cost you less than $50 and the time investment is also minimal--a couple of hours.

Note: This procedure requires some basic soldering skills (see references).

Flipper Overview and Variations

While all flippers are very similar in design there are a few variations.  In Image 1 you can see an exploded parts diagram for a flipper used in Williams Fliptronics games.  Image 2 shows a Williams flipper from a pre-Fliptronics game.

The first difference you will find between different flippers is the EOS (end-of-stroke) switch.  In some designs this will be a normally open switch (Image 1) while in others it will be a normally closed switch (Image 2). There are also two types of switches, low voltage (gold-plated) and high voltage.  They are not interchangable.

The switch wiring may also be different with some connected to the coil lugs while others will be connected to a circuit board (common on Fliptronics style games).  Some games will also have additional wires going to the switch to control the lane change functionality.

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Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers
Rebuilding Flippers

Note: There are some games that do not use an EOS switch and some that mount the EOS switch along with the flipper button.   Some games will have a second switch on the right flipper for lane change.

The next difference is the type of spring used on the flipper.  In Image 1 the spring (item 15) is connected from a tab on the crank link assembly to a hole in the switch mounting bracket.  Older style flippers (see Image 2) use a coil plunger spring (item 20).  The newer style is much stronger and many people will upgrade to this type of setup, which I'll cover later in the article.

There are two different styles of coils used in pinball games.  Older games will use a serial wound coil, while newer games will use a parallel wound coil.  The parallel wound coil was first used on F14 Tomcat and, in conjunction with a capacitor, greatly reduces the arcing on the EOS switch (instructions for upgrading can be seen below).

The next difference is the location of the coil diodes.  While most games will have the diodes attached directly to the flipper coil there are a few games where the diodes are mounted on a separate board.  If in doubt, check the schematics.

The last difference is games with parallel coils will have a capacitor across the switch (see Image 2).

In any case these differences only have a minor impact on rebuilding a flipper.  The main issue is to recognize there are variations so you're not trying to fix something that isn't broken.  For example, trying to modify a normally closed switch into a normally open switch (yes, I've seen it done) or adding diodes to a coil when the diodes are on a seperate board (also seen that done).

Inspecting the Flipper Mechanism

While some people will inspect and repair flipper parts rather than buy a kit, I really don't think the effort is worth it.  On the other hand there are times where you just bought a game and want to evaluate the condition of the flippers.  The following is what to look for to determine if you need to rebuild the flippers.

  1. Coil stop concave or mushroomed.
  2. End of plunger mushroomed or side heavily scratched.
  3. Play in the crank link (plunger) assembly joints.
  4. Cracked or broken coil sleeve.
  5. Pitted or corroded EOS switch contacts.
  6. Weak spring mechanism.
  7. Any binding or stiffness when manually moving the plunger.

Note: Flipper coils seldom go bad and other than an overheated coil, which is causing mechanical binding, will not cause weak flippers.  If the coil sleeve is almost impossible to remove and the new sleeve won't fit properly you may have an overheated coil and should replace it.

Upgrading the Flippers

There are two possible upgrades you can do when rebuilding flippers and neither is critical, just a matter of preference.  The first is updating to the newer style spring.  I typically do that upgrade since it's fairly fast and easy and solves several problems with the old design.  The second is updating from a serial to a parallel coil.  I typically do not do this upgrade since the only benefit is extending the EOS switch life and on a home game that's typically not a major issue.

If this is your first flipper rebuild I would skip both optional upgrades.

Flipper Rebuild Parts

You can either buy a flipper rebuild kit (see this page at Pinball LIfe) for your game or purchase the parts individually.  You can typically save quite a bit by ordering the parts individually, but you do take the risk of getting something wrong. 

The rebuild kit will typically include a coil sleeve (item 12a in Image 1), EOS switch (item 2), spring (item 15), crank link assembly (item 16), flipper stop assembly (item 11) and some misc. mounting hardware.  In Image 3 you can see the typical rebuild kit.  Note: The flipper bushing, bottom left, is not included in most kits.

If the flipper uses a capacitor they will normally be included in the kit.  If the kit does not include flipper bushings (see Image 3, bottom left), and most don't, you will want to order a couple.  Before placing your order check both flipper coils and make sure they are correct for your game.  There's a decent chance at least one will be the wrong value.

If you're upgrading to a Fliptronics style flipper (the newer style spring) order 2 of the flipper spring retainer brackets (Williams/Bally part number. 01-9376) and 2 flipper extension springs (Williams/Bally part number 10-364) in addition to the kit for your game (see Image 4).

If you have a system 11 game you can instead order the newer kit (Williams part number A-13524-8) and then purchase two high-voltage EOS switches (Williams part number 03-7811).  While this choice is slightly more expensive, you'll end up with a couple of extra gold-plated contacts, which are always useful. 

Or as mentioned earlier you can use the parts diagram to order the individual parts: coil sleeve, EOS switch (if applicable), spring (of the appropriate type), crank link assembly*, flipper stop assembly, flipper bushing, capacitor (if needed) and spring retainer bracket (if needed).

Note: In Image 4 and 5 the coil is installed backwards, which will increase the pounding the solder joints take.

It is common for the bumper plug (item 17 in Image 1, Williams part number 23-6577) to get damaged and they are not included in the rebuild kits so keep a few on hand.

If you are upgrading from serial coils to parallel coils, you will need to order the new coils (discussed below) and a capacitor (WIlliams part number 5045-12098-00).

If your game has a lane change switch in addition to the EOS switch, it wouldn't hurt to replace it while you're at it.

Don't worry about the mounting hardware.  Unless you strip a screw you won't need to replace them and if any washers or lock-washers are missing you can pick them up locally.

*There are two different crank link assemblies, one for the right flipper and one for the left.

Flipper Travel

Games made from 02/1992 (Getaway) to 04/1993 (Twilight Zone) have longer flipper travel and games made from 08/1993 (Indiana Jones) to 10/1998 (Cactus Canyon) have shorter flipper travel.  The difference is in the coil stop, so make sure to buy the correct coil stop or flipper rebuild kit for your game.  If you're not sure when your game was manufactured check IPDB.org.

Before Starting

The first step in rebuilding a flipper is to document the current setup since we will be disconnecting some wiring.  You can either photograph the flippers (make sure the wire colors and diode bands are visible) or make a drawing of the setup with wire colors noted.  You can also label the wires and associated connection points.

You won't have to mess with the diodes unless you're replacing the coil, and the new coil does not have diodes installed, or upgrading to parallel coils.  If that's the case make note of each diodes orientation and relationship to the color of the wire installed on that lug (use the end of the diode with the band as a reference). 

The capacitor has no polarity so it can be mounted in either direction.

It is not uncommon to find missing or incorrectly installed parts on a flipper.  Therefore it's a good idea to have a copy of the parts diagram handy if any questions arise.  Common problems include: coil installed backwards (see Image 5, the coil lugs should be at the opposite end), coil sleeve installed backwards (see Image 6) and washers missing.

Note: If the coil is installed backwards be aware that turning it around may change the perspective from your initial photo or diagram.  Also the coil wires may not be long enough to reach if the coil was installed backwards at the factory, which is actually very common.  Either lengthen the wires or leave the coil as is.

Since the two flippers are typically mirror images of each other, do one flipper at a time and you can use the other as a reference if needed (see Image 7).

Rebuilding Flippers

One small note of caution before you begin.  The windings of the coil use a very small gauge wire and the exposed portion can be fairly easily broken.  Just be thoughtful of this when working around the coil and the point where the windings are soldered to the coil lugs.

Loctite or Permatex Blue Threadlocker should be used on the nuts on the back side of the flipper bushing, the flipper stop assembly and the solenoid bracket.

Typically all mounting screws except those for the EOS switch and the flipper bushing have lock washers.  Check for and replace any that are missing.

If the EOS switch is wired to the coil take note of which lugs it is connected to.  Do the same if your flippers have a capacitor.  The direction of the switch and capacitor does not matter, just that they're on the correct lugs.

If you are upgrading serial coils to parallel coils read the information below in addition to this procedure.

  1. Either desolder the power and control wires to the coil or cut them and then desolder on the bench.  If you're going to cut them make sure there's enough length in the wire to still reach and cut them off where the insulation begins.  You'll typically want to use fresh, un-stripped wire anyways so cutting the wires is the easiest way to go. 
  2. If the EOS switch is connected to a circuit board rather than the coil, unsolder or cut the connections.  Do not cut any wires that go from the EOS switch or capacitor to the coil lugs, if there are any.
  3. Loosen the machine nut on the pawl (the part of the crank link assembly the flipper bat goes through, see Image 8) and remove the flipper from the top of the playfield.
  4. Remove the flipper assembly mounting screws from the bottom side of the playfield.
  5. Take the flipper mechanisms to the bench and if you haven't already unsolder the wires from the coil lugs, EOS switch and the capacitor, if there is one.  Unsolder the switch wires at the switch rather than at the coil.
  6. Completely disassemble the first flipper mechanism.  Note: Make sure on any phillips head screws to apply plenty of downward pressure or you'll strip them if they were installed with Loctite.
  7. Clean all of the parts with your favorite degreaser and a toothbrush.  Do not get the label on the coil wet or it will come off.
  8. Throw away the old parts and get your new parts ready.
  9. Inspect the bumper plug and if it is damaged replace it (see Image 9).
  10. Remove the flipper bushing (see Image 9)) and install the new one using Loctite on the mounting nuts.
  11. Install the new coil sleeve in the coil.  The sleeve should protrude from the end with the coil lugs (see Image 10).
  12. Install the new flipper stop assembly (item 2 in Image 7) using Loctite on the machine screws.  Do not completely tighten them.
  13. Put the coil in place with the lugs at the end away from the flipper stop assembly (see Image 7).
  14. Install the solenoid bracket (item 3 in Image 7) using Loctite on the mounting screws.  Do not completely tighten them.
  15. While squeezing the two brackets together (the flipper stop assembly and the solenoid bracket--see Image 7, flipper on the right) tighten the four mounting screws.  When you're done there should not be any play in the coil if you try to slide it towards either bracket.
  16. Install the new crank link assembly (item 1 in Image 7), including the coil plunger spring if you have that type of flipper and are not upgrading the spring.  Note: There is a right and a left crank link assembly so use the correct one (see Image 11).
  17. Install the new switch, if applicable, and since there is some play in the mounting adjust it parallel to the base of the flipper mechanism (see Image 12).
  18. If the switch was connected to the coil, attach the wires to the switch and solder them.
  19. If your flipper has a capacitor install the new one and mechanically connect the wires to the coil lugs (we'll solder them later).  Always put heat shrink tubing or the insulation from a small gauge wire over the capacitor leads.  Mount the capacitor to the switch mounting bracket using some double-sided mounting tape and then install a wire tie to hold the capacitor to the bracket.  Make sure the wires are routed so they will not get caught in the flipper mechanism or the switch (see Image 13).
  20. If you're using a flipper extension spring, install it now (item 4 in Image 7).  If you are upgrading to this type of spring, complete the following section and then install the spring.
  21. Temporarily install the flipper bat (the bolt only needs to be snug) and make sure the flipper mechanism moves smoothly.
  22. All that's left is to adjust the EOS switch, install the flipper mechanism, solder the coil lugs and adjust the flipper which we'll cover below

If you're not upgrading the coil or coil spring you can skip to here.

Converting to Newer Style Spring

As mentioned earlier it's easy to convert the older style coil plunger spring to a flipper extension spring.  You will need some parts as described in the flipper rebuild parts section.  Install the flipper spring retainer bracket on the crank link assembly as shown in Image 4.  There should be a washer and lock washer between the spring retainer bracket and the nut.

Next drill a 1/16" hole in the switch mounting bracket (see Image 14, the two smaller diameter holes).  The bracket in the image has a hole drilled for the spring on each side so it can be used in either flipper.  You only need to drill one hole, but it will be on the opposite side for each flipper.

Note: On some older games the switch mounting bracket will not be tall enough and will need to be replaced with part number 01-9375.

Install the switch mounting bracket and spring and you're done.

Upgrading Serial Coil to Parallel

These instructions are for converting an older FL24/600-30/2600 (standard strength) flipper coil to a FL11722 or a FL23/600-30/2600 (weak strength, usually used on upper playfield flippers) flipper coil to a FL11630, and apply to William games from High Speed to Millionaire.  This procedure should be done in conjunction with upgrading to flipper extension springs.

After installing the new flipper coil complete the following procedure.

The new coil will have three lugs and two diodes (see Image 20).  One outside lug will have a diode with the band pointing towards it and the other outside lug will have a diode with the band pointing away from it.  I'll refer to these as the banded lug and the non-banded lug, respectively.  Also, the banded lug will have both a large and a small coil wire attached to the lug and the non-banded side will have only a small diameter wire (see Image 20).

  1. Connect the EOS switch wires to the center lug and the outside non-banded lug.
  2. Install the capacitor (2.2 Mfd 250V) with one lead going to the center lug and the other to the outside non-banded lug.  These are the same two lugs as used for the EOS switch (see Image 13).  The direction of the capacitor does not matter. 
  3. As described previously put shielding over the capacitor leads, mount with double-sided tape and install a wire tie.
  4. At this point you can solder the center lug only or wait until you install the flipper assembly and solder all three lugs at once.

After installing the flipper assembly you will need to reconnect the power and control wires and it does matter which lug they go to.  The power wire should attach to the outside banded lug (the left lug in Image 20).  This will be the same wire that was connected to the lug on the old coil with the banded side of the diode.

Note: The old coil will only have one diode.

Connect the other control (ground) wire to the outside non-banded lug.  Solder all connections and don't forget the center lug if you haven't soldered it already.

Check the manual if you're having trouble with the power and control wiring.  The line on the diode drawing that the triangle points at correlates to the banded side of the physical diode.

Adjusting NO (normally open) EOS Switch

There are two critical adjustments that need to be made on the EOS switch (the flipper bat should be temporarily installed).  In Image 15 you can see the flipper at rest and the gap between the contacts should be .020".  Use the short contact leaf to achieve this gap.

When the flipper is energized and moves upwards there is a small arm on the crank link assembly that will open the switch (see Image 16).  Manually swing the crank link assembly and measure the distance this arm travels from the time it first closes the switch until you have reached the end of travel for the crank link.

In Image 16 the line on the left is the point the contact first closed and the line on the right is the end of travel.  I'm measuring the movement of the arm on the pawl, but you could also measure the movement of the long leaf switch.  In either case this distance should be 1/8".  Bend the longer contact leaf to adjust this gap.  You may have to go back and adjust the .020" at rest gap after making this adjustment.

Adjusting NC (normally closed) EOS Switch

On a NC switch, the switch should be closed when the flipper is at rest.  When the flipper is energized and at the end of its travel there should be a 1/8" gap between the contacts.  You may have to adjust both contacts to achieve the balance between these two positions.  Adjust the long contact leaf first and then the short contact leaf.

Reinstalling and Adjusting Flipper

Remove the flipper bat and reinstall the flipper mechanism in your game.  Using your photo or diagram solder the connections to the coil and EOS switch, if applicable.  It is important to adjust the up and down play in the flipper bat to ensure proper operation.  In the old days a "flipper shaft end play spacing gauge" was shipped with every game (see Image 17).

I haven't found anyone that sells these anymore but you can make on from an old credit card.  The tool is 1/32" thick and the u-shaped cutout should just fit around the flipper bat shaft. 

Install the flipper bat assembly and lightly tighten the nut on the crank link assembly that holds it in place (the bat should slide up and down with some pressure).  Place the gap tool between the flipper and the bushing (above the playfield). 

Note: This is easier than putting it between the flipper crank link assembly and the flipper bushing as per the instructions that come with the tool (see Image 17).  Push down on the bat from the top and push up on the crank link assembly from the bottom.

Note: You could also use a .030" feeler gauge.

Tighten the nut on the crank link assembly and remove the gap tool.  You should have about 1/32" play if you lift the flipper up and down.  Do not completely tighten the nut, we still want the bat shaft to rotate within the crank link assembly for our final adjustment.

On some games there are small holes in the playfield at the bottom end of the flipper for inserting a toothpick (see Image 18).  Place a toothpick in the hole and the center of each bat should align with the toothpick.  If your game does not have the holes or you want to be more exact place a straight edge along the lower ball guide and align the flippers with it (see Image 19).

At this point you can tighten down the flipper bat nut on the crank link assembly.

Other Tasks

This is also a good time to inspect and clean, or burnish, your flipper button switches and adjust them.  If they are in exceptionally bad shape it's best just to replace them.

If you have gold-plated, low voltage, contacts see the references.  For high voltage contacts use a burnishing tool.  Press the contacts together and move the tool back and forth between the contacts until you have two flat, parallel surfaces.

Adjust the flipper contact gap per your service manual.  This is especially important if the EOS switch is mounted on the flipper switch.