Rebuilding Pop Bumpers
Make your game play like it's new, or better!
By Vid1900
The only thing that strikes more fear into a new pinball owner's heart than setting the EOS Gap is rebuilding their Pop Bumpers.
There are always posts about how hard it is, but it really isn't hard at all. Like most complex tasks, rebuilding pops is quite easy, if you break it down into small steps.
A good machine needs strong Pops for fast action.
First label your wires. I know you can look it up in the manual, or even remember the wiring, but sometimes you get back to things much later than you think you will. Nobody ever complained that they took too many pictures or labeled everything too well.
Next unsolder the coil wires at the top of the bracket, and the lamp wires on the underside of the playfield.
Next unsolder the coil wires at the top of the bracket, and the lamp wires on the underside of the playfield.
Next pull the staples that hold down the Lamp leads.
You can put a sharp Scratch Awl under the staples and give them a light tap. Pull the staples out completely with a pair of pliers.
If the staple breaks, be careful to pull out any remnants.
There is usually a little piece of rubber or vinyl insulation that keeps the lamp from shorting against the bracket. You can reuse this, or use a piece of shrink tubing or even aquarium air line.
You can put a sharp Scratch Awl under the staples and give them a light tap. Pull the staples out completely with a pair of pliers.
If the staple breaks, be careful to pull out any remnants.
There is usually a little piece of rubber or vinyl insulation that keeps the lamp from shorting against the bracket. You can reuse this, or use a piece of shrink tubing or even aquarium air line.
Next remove the two 5/16" nuts (yellow handled nut wrench if you have a mechanic's set) that hold the Ring.
Be ready to catch the ring if you have the playfield upsidedown on a rotisserie, as it will drop away freely. Don't lose the two small washers that are on the underside of the Metal Yoke.
Be ready to catch the ring if you have the playfield upsidedown on a rotisserie, as it will drop away freely. Don't lose the two small washers that are on the underside of the Metal Yoke.
Here is the Ring, washers and nuts.
Can you tell what side of the ring the balls always hit on this particular game?
Can you tell what side of the ring the balls always hit on this particular game?
Next remove the three 5/16" nuts from the Bracket.
If the whole screw shaft is turning freely in the wood, grab the shaft with Vise-Grips and turn the nut with an open ended wrench. Make note to fill hole with wood epoxy, redrill and pound in a new "Fin Shank Screw" - the fancy name for those screws.
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If the whole screw shaft is turning freely in the wood, grab the shaft with Vise-Grips and turn the nut with an open ended wrench. Make note to fill hole with wood epoxy, redrill and pound in a new "Fin Shank Screw" - the fancy name for those screws.
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The whole Bracket lifts off and you can see the Spoon, the Switch Stack and the Lamp leads.
From the topside of the playfield, remove the Pop Bumper Cap and remove the two screws at the bottom of the Pop Body.
Gently lift the whole assembly out, don't scratch the playfield with the Lamp leads.
Gently lift the whole assembly out, don't scratch the playfield with the Lamp leads.
Now that you have it out, it does not look that complicated, does it?
Now, let's start the rebuild.
Unless you want the look of yellowed plastic (don't laugh, on older games it often looks best), I'm assuming most of these parts are going to be brand new. They are very inexpensive, so replace them if at all possible.
First, put down the new Base into the Pop Bumper hole in the playfield.
Rotate the Base so the large base holes line up with the playfield screw holes.
Unless you want the look of yellowed plastic (don't laugh, on older games it often looks best), I'm assuming most of these parts are going to be brand new. They are very inexpensive, so replace them if at all possible.
First, put down the new Base into the Pop Bumper hole in the playfield.
Rotate the Base so the large base holes line up with the playfield screw holes.
Next install the Skirt Spring, also referred to as the "Small Spring".
Place the Skirt on the Spring.
Note the the two widely spaced holes go over the large holes in the playfield. You can't really mess this up once you look at it. The Ring rods travel through those holes.
Note the the two widely spaced holes go over the large holes in the playfield. You can't really mess this up once you look at it. The Ring rods travel through those holes.
Next the Body snaps into the Base.
Note how the larger holes line up with the screw holes and not the Lamp lead holes. Again, you are not going to mess this up, but watch for it.
Note how the larger holes line up with the screw holes and not the Lamp lead holes. Again, you are not going to mess this up, but watch for it.
Here we slide in the Lamp holder through the small Lamp lead holes.
Push it all the way to the bottom.
Push it all the way to the bottom.
If you somehow got stuck with the flexible wire lead Lamp Holders, you have now probably discovered that they won't go down very far into the Body, and tend to fall to one side or another.
You need to fix this with a Zip-tie so the Holder can go all the way down to the bottom of the body.
Next time, make sure you buy the stiff wire leads, LOL.
You need to fix this with a Zip-tie so the Holder can go all the way down to the bottom of the body.
Next time, make sure you buy the stiff wire leads, LOL.
Next you can install the bulb.
If you are using a LED Lamp, don't put the bulb in yet, as you may have to reverse the bulb to get the polarity right (depending on the game).
If you are using a LED Lamp, don't put the bulb in yet, as you may have to reverse the bulb to get the polarity right (depending on the game).
The cap goes on with two screws.
Again, don't put the cap on yet if you are using LEDs. Once you have the game powered up, THEN you will find if the bulb needs reversing (literally pull it out and replace it 180°).
Again, don't put the cap on yet if you are using LEDs. Once you have the game powered up, THEN you will find if the bulb needs reversing (literally pull it out and replace it 180°).
Now that the topside of the bumper is completed, we go under the playfield to the Bracket assembly.
First, take a look at the Coil and see if it is the correct model for your game (usually the required coils are listed on the inside cover of the manual).
Don't be surprised if you have a smorgasbord of mismatched coils, as most operators only cared about keeping the game working, not how well it played.
Take the two screws off the back of the bracket and the whole assembly will come apart.
First, take a look at the Coil and see if it is the correct model for your game (usually the required coils are listed on the inside cover of the manual).
Don't be surprised if you have a smorgasbord of mismatched coils, as most operators only cared about keeping the game working, not how well it played.
Take the two screws off the back of the bracket and the whole assembly will come apart.
Now that you have the Bracket apart, inspect the Plunger for wear. If it's not smooth and shiny, replace it. If the end is mushroomed, replace the Plunger and the Bracket; as it's probably too worn to fool with. If the Plunger has become magnetized and is covered with metal shavings, replace it.
Clean any parts you are keeping with Fantastik or any other degreaser using an old toothbrush. Clean inside the Coil too.
Replace the Sleeve. If it's stuck tight in the coil, press the protruding part down flat on your workbench and push it out. If it is hopelessly stuck, replace the coil (it probably overheated at some point, and could be a liability latter on). Remember that the lip on the Sleeve goes on the diode end of the coil.
The Bracket has 2 yokes. The metal one is almost always broken, the fiber one is always worn. Always replace them both.
Make sure both screws are the type with lock washers installed on them. If the Yoke Retaining Bracket comes loose, the Plunger will become damaged.
When reassembling the Bracket, remember to press the Yoke Retaining Bracket towards the Coil Stop end of the Bracket as you tighten the screws. By doing this you will ensure that there is no slop in the Coil; and thus all the energy will be transmitted to the ball. The Coil should NOT be loose or have any play.
Clean any parts you are keeping with Fantastik or any other degreaser using an old toothbrush. Clean inside the Coil too.
Replace the Sleeve. If it's stuck tight in the coil, press the protruding part down flat on your workbench and push it out. If it is hopelessly stuck, replace the coil (it probably overheated at some point, and could be a liability latter on). Remember that the lip on the Sleeve goes on the diode end of the coil.
The Bracket has 2 yokes. The metal one is almost always broken, the fiber one is always worn. Always replace them both.
Make sure both screws are the type with lock washers installed on them. If the Yoke Retaining Bracket comes loose, the Plunger will become damaged.
When reassembling the Bracket, remember to press the Yoke Retaining Bracket towards the Coil Stop end of the Bracket as you tighten the screws. By doing this you will ensure that there is no slop in the Coil; and thus all the energy will be transmitted to the ball. The Coil should NOT be loose or have any play.
The plastic Spoon on the front of the Switch Stack should be replaced.
Often the ball will hit the bumpers from one direction and the inside spoon surface will wear in a pattern, or even a straight groove.
The Switch Stack has some room for adjustment so that the center of the Spoon can be directly over the center of the Skirt Pin. Loosen the two screws a bit so you can just move the Switch around.
Often the ball will hit the bumpers from one direction and the inside spoon surface will wear in a pattern, or even a straight groove.
The Switch Stack has some room for adjustment so that the center of the Spoon can be directly over the center of the Skirt Pin. Loosen the two screws a bit so you can just move the Switch around.
Many spoons are translucent plastic, assuming yours are, you can use the following operator's trick:
Use a strong beam of light to illuminate the underside of the spoon.
Look at The Shadow cast by the contact point between the Skirt Pin and the Spoon.
Use a strong beam of light to illuminate the underside of the spoon.
Look at The Shadow cast by the contact point between the Skirt Pin and the Spoon.
Move the Switch Stack around until the Skirt Pin is exactly in the center of the spoon.
Check your work by tapping your finger in the center of the Spoon. If the Skirt Pin is truly centered, there will be no play or movement. If not centered, you will notice the Pin will slightly veer off to one side as you tap. Purposely misaligned the Spoon to learn this effect.
If you spoon is black or an opaque plastic, use the tapping technique as above.
Tighten the screws on the Switch Stack and double check that your Pin is still in the center of the Spoon.
Check your work by tapping your finger in the center of the Spoon. If the Skirt Pin is truly centered, there will be no play or movement. If not centered, you will notice the Pin will slightly veer off to one side as you tap. Purposely misaligned the Spoon to learn this effect.
If you spoon is black or an opaque plastic, use the tapping technique as above.
Tighten the screws on the Switch Stack and double check that your Pin is still in the center of the Spoon.
Once the Spoon is centered, put your now reassembled Coil Bracket back into place.
Resolder your Lamp leads and the Coil leads.
Clean the switch contacts with a crisp dollar bill. Gently press the contacts together while pulling the bill between them, repeat until bill comes out clean.
Here is a picture to explain how all of the parts fit back together around the Switch Stack.
Resolder your Lamp leads and the Coil leads.
Clean the switch contacts with a crisp dollar bill. Gently press the contacts together while pulling the bill between them, repeat until bill comes out clean.
Here is a picture to explain how all of the parts fit back together around the Switch Stack.
When the Pop Bumper is at rest, we want the Solenoid Switch to have a very small gap so that the Bumper has a "hair trigger" (this reference comes from fire arms, where a small amount of force (I guess a human hair) can set off the firing pin).
On a pinball game, we want the slightest amount of force to trigger the bumpers so they are VERY lively.
When the game is powered on, pound on the playfield a few times and make sure that the Pop Bumpers do not activate from vibration alone.
On a pinball game, we want the slightest amount of force to trigger the bumpers so they are VERY lively.
When the game is powered on, pound on the playfield a few times and make sure that the Pop Bumpers do not activate from vibration alone.
The Scoring Switch activates whenever the Pop Bumper fires. The Solenoid drives the Fiber Yoke into closing the Scoring Switch.
The Gap on the Scoring Switch is not very critical. As long as the contacts touch before the last 1/8" of travel it should be fine. This last bit of travel lets the contacts slide across each other for self cleaning action.
The Gap on the Scoring Switch is not very critical. As long as the contacts touch before the last 1/8" of travel it should be fine. This last bit of travel lets the contacts slide across each other for self cleaning action.
So that's it. Once you have done it, figure about 10 minutes per bumper to rebuild them.
Again, most of these parts are very inexpensive, so don't waste time cleaning or filing old ones.
Newer Bumper Bodies are much less translucent that the old ones, so a 5 LED lamp may be needed to illuminate as well as the old incandescent 555 did.
Again, most of these parts are very inexpensive, so don't waste time cleaning or filing old ones.
Newer Bumper Bodies are much less translucent that the old ones, so a 5 LED lamp may be needed to illuminate as well as the old incandescent 555 did.
There has been a lot of time and energy put into creating this guide courtesy of Vid1900 and we all thank him for his contributions to this website. There are sure to be updates to the guide as well so please check back, pass along and feel free to use any and all of the information contained in the guide.
If you would like to follow the thread on this guide with questions and answers please see it here via Pinside
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