General

3 The Switch Matrix

All solid state pinball machines implement a "switch matrix." The switch matrix is comprised of "strobe lines" (generally 8) and "return lines" (also generally 8). At the intersection of each strobe and return line, an isolation diode in series with the actual switch, connects the strobe line to the return line.

The reason for implementing a switch matrix is easily understood: economy of wiring. To sense 64 switches, a total of 16 wires are required using a switch matrix. If the designers had chosen to sense those same 64 switches individually, a minimum of 65 wires would be required.

How a switch matrix works

Conceptually, operation of the switch matrix is pretty simple. The CPU commands the return circuitry to "listen" for a pulse on each row simultaneously. The CPU then commands a strobe at column 1. Any switch that is closed on column 1 will cause the signal to be propagated down the row return where the CPU will "hear" it. A return on row 1 after pulsing column 1 means that the switch at position 1,1 in the switch matrix is closed. The CPU then moves on to column 2 and repeats the same steps. After all 8 columns are strobed, the CPU then returns to column 1 and begins the whole process again. This continues as long as the game is powered on.

Note that the actual electrical circuit implementation is quite a bit more complex than this conceptual description and may be found in the particular manufacturer's section of the Wiki. Also note that a "pulse" in this context might not be a "high" signal but instead a "change in state" (from logic 1 to logic 0 or vice verse).

A representation of the Bally/Williams WPC switch matrix is shown in the picture below. The column strobes are represented by the vertical lines. The row returns are represented by the horizontal lines.

General Switch Matrix Debugging Tips

Switch matrix problem diagnosis always begins with determining whether the problem is on the CPU or on the playfield.

Under construction...
Discuss using a diode/jumper to connect row and column at the CPU board.
Discuss finding the "at fault" switch if the problem is on the PF.
Insert animation created by Hibler/Palson here.

4 The Lamp Matrix

Under construction...
Discuss general lamp matrix operation here

Most games have a lamp matrix. Every Williams, Data East, and Sega pinball has a lamp matrix. All Stern Pinball games have them, but old Stern Electronics games do not. Bally games based on Williams' System 11 and WPC systems have them. Gottlieb System 3 games also have a lamp matrix, but it's a hybrid with the switch matrix.

Other manufacturers' games drive lamps with individual transistors. This applies to all Bally games, Stern Electronics games, Atari games, and Gottlieb System 80 and System 1 games.

Under MPU control

 For a particular lamp column
   Enable returns on the appropriate rows
   Strobe the column
 Next lamp column

5 How are coils driven?

Under construction...
Discuss "finding ground" via a controlled transistor to turn on a coil.

Every coil will have power "waiting at the ready" at the coils lugs. All that is required is for the ground lug of coil to find a path to ground. This is accomplished by "turning on" a transistor.

6 Flippers

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How does a flipper work?

Flippers have two coil windings. One is a high powered, low resistance winding, used for the power stroke (initial "flip"). The other is used to keep the flipper held up, when you are holding the flipper to trap a ball. There needs to be a mechanism to switch from the high powered side to the low powered side. The high powered side of the coil is almost a dead short, and anything other than a momentary activation would cause the fuse to blow.

High Voltage flipper operation

The original flipper operation was completely high voltage, requiring tungsten point contacts at the flipper switches and at the normally closed end of stroke switches. These switches need to be filed periodically and gapped correctly for proper operation. A maladjusted end of stroke switch can burn out a coil or a fuse as well as damage the plastic bobbin the coil is wrapped around, making for sluggish operation. Tarnished and burnt contacts at any point in the system can cause a weak flipper power stroke, making for diminished game play. Additionally, there are contacts on a machine's flipper relay that may need to be cleaned to provide the maximum power to the flippers. Connectors and header pins can also play a factor in a flipper's power; heavily tarnished connections will degrade performance.

When you press a flipper button, you are actually grounding the flipper circuit, not providing the power. The power is already present at the coil's input lug. The power flows from the power supply to the flipper coil in the most direct path possible. The input lug has the solenoid power present: one wire going to one blade of the end of stroke switch, and one end of the hold winding; one end of the high powered coil's winding is attached to the other blade of the end of stroke switch.

The flipper button has one contact attached to the terminus of both flipper coil windings; the other contact is attached to ground via the flipper relay. When the flipper relay is pulled in a ground path exists for the flipper. When it is deactivated (in game over/tilt modes) there is no ground path for the flippers. When you push the flipper button, the power travels through the end of stroke switch, the high powered coil, through the flipper cabinet switch, and the relay to ground, pulling the flipper in with great force.

A small arm on the pivot point of the flipper presses against the end of stroke switch outer blade, moving it away from the inner blade. This cuts the high power to the stroke side of the coil. Because the hold coil still is getting power via the input lug, the flipper will stay in an up position as long as you hold the button in. The hold coil has much greater resistance and so does not blow the fuse or create a short circuit.

Solid State Flipper operation

Solid state flippers do not refer to flippers in any solid state machine; rather, they refer to a design in later machines (post 1989) to eliminate the traditional high powered tungsten contacted type of flipper, which was subject to degradation over time. Less maintenance is required for solid state flippers.

There are a few different designs to eliminate the high power switches used with flippers. One circuit monitors the time the flipper is held in; anything over 50-100 milliseconds continuous activation switches the power to the low side of the coil from the upper side electronically. Some designs of this nature also have a low powered normally open end of stroke switch, so that the flipper feels more like a traditional flipper. The time function of the solid state circuit only comes into play if the end of stroke switch is never detected, switching the power to the hold coil. Williams Fliptronics(tm) flippers operate in this fashion.

Another design monitors the end of stroke switch/time and pulses the power supply to the flipper to reduce the voltage during the hold cycle. This allows a cheaper coil to be used as there is only one winding on the coil. Examples of this type of PVM flipper are late model Stern games. Sometimes the pulsing of the voltage causes the flipper to buzz slightly.

7 Lamp Chart

Lamp	Voltage (V)	Current(A)	Candle Power	Life (hours)	Base	Typical Use
44	6.3	0.25	0.9	3,000	Miniature Bayonet (BA9)	Common GI bulb
47	6.3	0.15	0.5	3,000	Miniature Bayonet (BA9)	A low-power version of the #44; reduced heat and candle power
55	7.0	.41	2.00	500	Miniature Bayonet (BA9)	Used on some EM games, high current, heat and candle power compared to #44 and #47
67	13.5	.59	4.0	5,000	S.C. Bayonet (BA15s)	F-14 Tomcat Flash Lamps
73	14.0	.80	.30	15,000	Wedge (T 1-3/4)	A low-power alternative for the 86 used in Twilight Zone's clock mechanism
86	6.3	.20	.40	15,000	Wedge (T 1-3/4)	Small lamp used in Creature from the Black Lagoon ramps and Twilight Zone's clock mechanism
89	13.0	.58	6.00	750	S.C. Bayonet (BA15s)	Flash Lamps on many Sys11/DE/WPC
194	14.0	.27	2.00	1,500	Wedge	Whitewater Topper Lamps
199	12.8	2.25	32.00	1500	S.C. Bayonet (BA15s)	HS2 Getaway Topper Lamp, CFTBL Hologram Lamp
313	28	0.17	3.5	500	Miniature Bayonet (BA9)	Used for lower playfield illumination on Black Hole and Haunted House
447	6.3	0.15	0.5	3,000	Wedge	A low-power version of the 555; reduced heat and candle power
455	6.5	0.5	N/A	500	Miniature Bayonet (BA9)	Blinker
545	6.5	0.31	N/A	500	Wedge	Blinker - used in Twilight Zone, Dirty Harry, No Good Gofers
555	6.3	0.25	0.9	3,000	Wedge	Common GI bulb
906	13.0	.69	6.00	1000	T-5 Wedge	Flash Lamp
1251	28.0	.23	3.00	2,000	S.C. Bayonet (BA15s)	Pin-Bot and Cyclone Flash Lamps
1683	28.0	1.02	32.00	500	S.C. Bayonet (BA15s)	High Speed Topper Lamp

Notes:

1. A "blinker" is a lamp with an internal thermal switch (a bi-metallic strip) that interrupts power to the lamp causing it to blink on and off; the cycle is usually a few seconds. These are often used behind the title on EM games. A "flash lamp" is a lamp that is purposely over-driven for a brief instant (milliseconds) to produce an extremely bright flash of light. These are used to draw attention to game features such as bonuses.
2. 47 lamp is often used as a replacement for 44 lamps where heat is a concern for backglass or plastics.
3. 447 lamp serves the same purpose replacement for 555 lamps.
4. Candlepower is measured in Mean Spherical Candlepower (MSCP)
5. T-3 1/4 refers shape and size, for example T-3 1/4 is "tubular", 3.25 8ths of an inch in diameter

Detailed specifications on lamps is available at http://www.donsbulbs.com . Just enter the lamp number in the "Bulb Search" field.

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9 Fuse Table

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Pinball Machine Fuse TableSome games may have different fuses and quantities

Qty	Bally EM		Qty	Gottlieb EM		Qty	Williams EM
2	5A	BR, DC coils	2	2A SB	Drop target bank	6	10A	Main, BR, coils
2	8A	Main line fuse	2	5A SB	Main line fuse	6	15A	Lamps, coils
4	10A	Coils	4	10A	Lamps
4	15A	Lamps	4	15A	Coils
Qty	Atari		Qty	Bally/Stern (1977-1984)		Qty	Gottlieb Solid-State
2	1A SB	Power supply	3	1A SB	Coils-under PF	2	1/4A SB	Displays
1	2A SB	Service outlet	1	3A SB	Main line power	1	1A SB	Coils
1	5A SB	Main power	1	3/16A	High Voltage on SDB	2	2A SB	Drop target bank
2	7A SB	Power supply	1	3/4A	Display power supply	4	5A SB	Main, coils, lamps
2	10A SB	Power supply	1	4A	12v/5v power supply	2	8A	Lamps
4	15A SB	PS, lamps, displays	3	5A	Coils	1	10A	Lamps
			2	15A	General Illumination
			1	20A	Switched Lamps
Qty	Williams L3-L7 (1977-1984)		Qty	Williams System 9-11 (1985-1990)		Qty	Williams WPC (1990-1994)
1	1/4A SB	Display high voltage	1	1/4A SB	Power supply (displays)	1	3/8A SB	Display driver board
3	2-1/2A SB	Coils	5	2A SB	Aux board	4	3A SB	Coils, flippers
2	4A SB	Sound board	2	2-1/2A SB	Coils	3	5A SB	Power supply, lamps
2	7A SB	5v power (L7 games)	2	4A SB	Coils, flippers	1	7A SB	Power supply
2	8A	Main, switched lamps	6	5A SB	Flpr, aux, cab, lamps	1	3/4A	12v power supply
2	20A	General illumination	2	7A SB	Power supply	2	8A	Main, switched lamps
			2	1/10A	Cabinet, displays
			1	3/4A	12v power supply
			2	8A	Main, switched lamps
Qty	Data East		Qty	Sega & New Stern		Qty	Williams WPC-95 (1995-1999)
3	3A SB	Coils, flippers	1	3/4A SB	Display	2	T0.315A SB	Display
2	4A SB	Coils	4	3A SB	Coils, flippers	1	T0.63A SB	12v PS F101
4	5A SB	Lamps, power supply	1	4A SB	Power supply	5	T4.0A SB	Cls,5/12v,lmps,flsh,flpr,ln
2	7A SB	Power supply	4	5A SB	Coils, lamps	1	T5.0A SB	Switched lamps, line
1	8A SB	Line, power supply	1	7A SB	Coils	1	T6.3A SB	Coils main F108
			1	8A SB	Power line, lamps	2	T2.5A	Audio F501, F502

10 Tuning a Game for Best Performance

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10.1 Leveling the Game

One of the most important things you can do to tune a game is make sure the playfield is level side to side. Some games contain a bubble level on the apron to check side to side leveling. Do to differing floor conditions, any time a game is moved, the level should be checked. Use an inclinometer or small torpedo level to check the side to side level. An inclinometer application can be used on a smartphone, as well. Check the level on the playfield itself, NOT on the playfield glass. The playfield may not sit level in the cabinet, or may be warped. Check the the level at several points on the upper and lower playfield. Adjust using the leg levelers. After your done, make sure you tighten the locknuts on the levelers.

10.2 Adjusting the Game Pitch

The pitch of the game drastically affects game play. A steeper game plays faster. Too steep can tax the flippers ability to make ramp shots. Too shallow, slows the game down. Too shallow can also allow the ball to be redirected more by playfield irregularities, such as warped inserts. Again, due to differing floor conditions, any time a game is moved, the pitch should be checked. The proper pitch of a given game may be indicated in the manual. In the case of games which include a bubble level for pitch, the manufacturers recommendations may be marked on the level. In the case where a recommended pitch is not indicated, the generally accepted "Rule of Thumb" is 3 1/2 degrees for EM games and 6 1/2 to 7 degrees for Solid State Games. Use an inclinometer, again on the playfield itself NOT the playfield glass, to measure pitch. Adjust using the leg levelers. After you're done leveling, make sure you tighten the locknuts on the levelers.

Some players will adjust the pitch outside of "Factory" settings, to suit their taste or playing style. After playing a game for a while on the "Standard" settings, you may wish to experiment with different pitches.

10.3 Balls

Inspect the balls in a game regularly to ensure none are pitted or becoming rusty. A damaged ball has the potential to strip playfield ink in a very short time. Keep the balls clean and polish them occasionally with a soft cloth; try not to put balls back in the machine that have skin oil on them. Transfer from the cloth directly to the machine.

The more close to round a ball is the better/more wild it will play. Balls are just ball bearings, and are manufactured to tolerances up to .001%. You don't need a ball that true to put in a pinball, but if you can afford them, they would play very well. Buying pinballs from a reputable supplier is fine; a pinball costs between 90 cents to 5 dollars depending on finish and tolerance.

10.4 Adjusting flippers

Nothing impacts a game's performance more than the performance of its flippers. The entire game can be smooth playing and work properly, yet with bad flippers no one will enjoy it to its full potential. The proper rebuilding and tuning of flippers impacts a game's performance about 70% vs. 30% for all the other parts in the game.

High voltage end of stroke switches need to be filed flat or replaced and should open with between 1/8"-1/4" gap at full extension. Flipper cabinet switches need to be filed and dressed as well, provided they are heavy, tungsten contacts. Do not file cabinet switches of games which use solid state flipper assemblies. These switches are gold plated. Filing will remove the plating and ruin the switch. For those switches, draw an old business card between the contacts as you pinch them together. This will clean the contacts sufficiently. Any connector in the flipper power path should be replaced or eliminated if possible (for instance, games that use spade lugs to attach their flipper button blades should have their wires soldered directly to the blade instead). Flipper relays need to be cleaned and contacts dressed as well, and their solder mount points re-flowed.

The angle of the flipper should be adjusted to the slope of the inlane guide (if present) and the inlane guides tweaked (either by slight movement or bending if wire type) so that no ball hop off the lane guide occurs. This issue is especially prevalent on Bally games with wire guides and early Williams' solid state games with flat metal guides; the flat metal edge gets hammered over the years as well as the guide itself loosening in its mounting screws cause it to sit lower than intended. Games without inlane guides should be checked against a reference (flyer) picture to determine the proper play angle, but some leeway is permitted here in the interests of gameplay. Under no circumstances should an opposing pair of flippers be adjusted so that one rests higher/lower than the other, nor both flippers extended not be at the same height.

The flipper bat should have a slight up-down play as you pull away from the playfield at both its rest position and extended position. Swapping worn parts from left to right or the reverse can help you re-use worn parts where replacements are not available. Rebuild and redress any worn out parts if at all possible. Reverse all hacks over the years to restore the play to its original intentions.

Some mechanisms (Bally linear flipper mechanism spotlighted) benefit from having earlier style parts (plunger, link, and pawl) swapped into their assemblies for better flipper action. The linear flipper while fine when new has a fast-wearing part in the form of the nylon bearing on its lever assembly; the earlier style parts swap in place no problem and last much longer, as well as being a zippier flip thanks to the lighter mass of its parts.

10.5 Adjusting drop targets

Most drop targets are made of plastic and are made to run 'dry', i.e. no lubrication. If you must lube them, use graphite powder or a lube specifically made for plastic on metal. Note that any lube used will tend to make the area under the playfield very messy so use very sparingly if at all. The first order of business is to disassemble the drop mechanism and clean every part very, very well. For metal parts use a metal polish to make sure there are no really sharp edges or burrs to cause wear. You might have to use a small file to dull any sharp edges. Plastic drop parts polish with Novus 2 after cleaning any grease off with a degreaser safe for plastics (simple green works well).

Williams targets with contacts that ride on a circuit board would benefit from a very light application of DeOxIt. The later targets that depend on a copper blade for forward tension you can use teflon lube on the copper blade; wipe it on with your finger and wipe almost all of it off. You want the least amount of lube possible. The copper blade can be bent but be careful as the blade should be flat along its length; you want JUST enough tension so the target presses forward, but not so much that the target won't fall when you hit it.

When you reassemble Williams drop banks, do not over tighten the screws that hold the metal bars to the plastic bosses - you will ruin the tension on the drop bank and possibly crack the screw boss, rendering it useless (these parts are currently unavailable new). Just snug the bar down to the drop bank and let the lock washer do its job holding it on.

Gottlieb drop targets are the best designed and built targets in the business. As usual, Gottlieb didn't cut corners with their design, so there are 2 discrete springs used to pull the drops in the proper directions to reset correctly, and provide the correct spring tension on the pulldown stroke. Additionally, the reset mech is mounted at an angle so the drops reset smoothly and correctly. Gottlieb drops should be adjusted to reset approximately 1/16 of an inch "above" the bank's top plate. You can loosen the reset coil mounts to slide the coil into place to accomplish this. Letting them reset too high (caused when the coil mount migrates to the bottom of its travel) will tend to break off the "foot" on each drop target. Once this happens a Gottlieb drop can reset in a very awkward position, higher than it should be; a snappy ball hit when it's in this position often will snap the target in 2.

Bally drop targets come in 2 varieties - "tombstone" and "flattop". The flattop ones were designed for games that use an inline drop target assembly (Paragon, Fathom, Eight Ball Deluxe, others) or a single drop target where the ball travels over the drop target (Flash Gordon, Rolling Stones, others). The flattop targets that have a ball path over them need to be adjusted so the target top is flush with the playfield so the ball can travel over them easily. On a single drop, you can bend the foot that's under the drop target stem to accomplish this, or loosen it and move it up or down to accomplish the same thing. On an inline bank mechanism, you want to adjust the bottom foot plate to do the same thing, which can be difficult for the center targets. Some experimentation is necessary here.

For Bally flattop drops that aren't in an inline configuration you want the drop to sit very slightly above the playfield surface (1/16 inch or less) - this is so a ball will not tend to get stuck in the slot formed by the target spaces and the playfield. Adjusting the height the drops rest at can be accomplished by moving (or bending) the foot plate or adding a spacer made out of shims (cardboard, thin metal, etc.) Install the shim on the top of the bottom frame where the foot of the plastic target rests. You can use tension clips or even a paper clip to hold your shim in place, just be sure it doesn't interfere with the operation of the targets or reset mechanism.

The thickness of the Bally drops sometimes cause what's called "bricking" of the drop targets - a hard shot to the drops will result in the ball bouncing off the target (sometimes snapping it in half!) but the drop not dropping. There are a couple things you can try to fix this, but there's no one definitive solution that works (other than swapping in a Gottlieb target bank if you can!) - some of the things you can try are shaving a minute angle into the drop shelf where the target sits at rest under tension, changing the angle of the spring, changing the tension of the spring, and moving the entire bank inside the slot as far forward as possible. Some more radical solutions over the years have been tried to fix this issue. Adding extra springs, epoxying spring steel to the back of the target, melting notches into the target with a soldering iron, beveling the under playfield area with a chisel, changing the rubber behind the targets (fat rubber makes the bricking worse), and changing the posts behind the targets to a smaller size have all been tried with varying degrees of success, but none have fixed the issue 100%.

The newness of the drop target seems to be directly proportional to its propensity to brick; the older the drop, the more it tends to drop smoother because of years of wear. This is particularly poignant with classic Stern drop targets; they are similar to Bally drops but the reset shelf is lower on the target itself; a Stern drop can be modified to work in a Bally machine, by shaving this rib off, but not recommended as classic Stern drop targets have not been available in the "chichlet" style for over 25 years.

Classic Stern drops were originally similar to the "tombstone" Bally style (they're called "chichlets"), and worked well (overall the non-flattop style of drop works well in terms of non-bricking, but often a ball could be come trapped between targets). Adjusting the down position of the targets is similar to the flattops but with slightly more height vs. the pf, 3/32" vs. 1/16". A radical solution to this if you get this problem constantly would be to glue a piece of wood cut to fit between the targets and the slot and glued into place eliminates the gap that the ball gets stuck in, but this is a very radical solution and not recommended for most machines.

The metal parts on classic Stern drop mechanisms tend to wear and need metal cleaning/polishing to be refurbished properly. Teflon lube should be used very sparingly (wipe on, wipe almost all off.... if you can see it, it's too much) on any metal to metal contact points. Any metal coil sleeves used in drop mechanisms should be replaced with the proper sized nylon sleeves instead. The metal fingers where the drop targets contact their switches need a slight bit of lube also, less than used anywhere else. The switches themselves need to be adjusted to provide the least amount of drag to the dropping finger but still also contact enough pressure to provide some wiping action to the 2nd switch contact.

Adjusting a drop bank so that a balancing act is performed can be a bit of an art; you want the least resistance to dropping and resetting possible while still maintaining all drops resetting properly every time. There's nothing more frustrating from a player perspective than making a good shot on a drop target and it not dropping. If adjusted properly a bank can be 'swept' with an oblique flipper shot, all drops including the stubborn tending Williams and Bally drops will sweep if clean and adjusted carefully.

10.6 Tweaking a pop bumper

Pop bumpers should be adjusted so the slightest touch of a ball at any point causes them to activate, but not be so sensitive that vibration causes them to activate. Clean the spoon switch actuator very well. If it's plastic you can use novus to polish it. If it's metal some 2000 grit sandpaper will polish it nicely. On solid state or EM machines with high voltage points, you should file the switches clean and flat. On machines with gold flashed contacts, inspect them well and clean with brasso, alcohol, or a business card wiped between the points. If any part of the gold plating is breached, replace the contact with a new one. Gold plated contacts with missing plating will never be 100% reliable again.

Adjust the position of the spoon switch underneath the skirt's actuator so that the pin sits naturally in the center of the spoon switch. The spoon switch bracket has oblong mounting holes for exactly this purpose. Once it's positioned in the center, tighten the switch bracket mounting screws. Now, using a contact adjuster tool, adjust either the spoon blade itself (for metal ones) or the blade that provides the tension to the plastic spoon so that there's barely tension on the actuation pin (the softer this adjustment, the more sensitive the pop bumper will be). You want enough force so that the spoon re-centers the pin, but not so much that anything other than a hard ball hit activates the bumper. With the playfield raised you can activate the pop skirt by hand to see how much to adjust the spoon. It takes several tries to get this right, but it's well worth taking the time to do this.

Adjust the second blade to between 1/16"-1/8" gap between the contacts of the first blade. This will vary depending on if the machine uses high voltage activation of pop bumpers or not. You want the gap close enough so the pop is sensitive, but not so close that other mechanisms in the machine activate the pop. A good way to test this is to adjust the switch, then with the playfield lowered, make a fist and pound on the playfield in the area of the pops.

Some machines that use direct activation of pops might benefit from wiring in a Gottlieb pop bumper driver board. This applies mostly to Gottlieb System 1 solid state machines, but could also be used on some early Williams games as well as specialized purposes on other games. Basically, high voltage activated switches can pit and arc; generally, they require a slightly larger gap to ensure the contacts do not weld together from the arcing. Using a pop bumper driver board on this type of bumper with the actuation contacts changed to gold flashed type allow a closer switch gap, and the board provides a solid activation regardless of how hard the skirt was hit.

A specialized purpose for a pop bumper driver board would be on a Stern 9 Ball, for the lone pop at the top. Bally/Stern machines do not have the ability to fire more than one momentary solenoid simultaneously; this comes into heavy play on 9 Ball as the drop banks reset and drop their targets. It is possible for the top pop to not fire while this resetting is going on, especially if the game is set to require both 3 bank drops to reset to advance the bonus multiplier. The scenario is this: You drop both banks and the ball hits the pop.... with a thud. You receive score for the hit, but the pop doesn't fire because the 2 3 bank drop targets are still resetting. Changing the pop to activate with a pop bumper driver board removes the hardware limitation from the equation, as the pop is able to activate on its own; the mpu still scores the pop as a secondary switch gets added similar to Gottlieb System 1 games or early williams games.

For a while Wico made a plastic pop bumper assembly that used a plastic rod and ring combination. This was used on their game Af-Tor and also on Stern machines starting around Cheetah to the end of classic Stern production. This plastic rod and ring weighs much less than the metal assembly normally used, and can be swapped into the metal type with a little effort. The resulting quicker reacting pop is amazing in its smoothness and reaction time; you will get much better pop action with this substitution. It works even better than putting a stronger coil in the metal ringed pop bumper assembly, which will also pop the bumper quicker, but the moving mass of the metal rod and ring still make that combo slower reacting. Game plan may have used this plastic combination for a while also, as did Pinstar's Gamatron conversion kit.

10.7 Tuning a spinner

Nothing beats a solid spinner hit, spinning and racking up points at a furious pace. On the flip side, nothing sucks the enthusiasm out of a nice shot more than a spinner weakly spinning a few times lethargically, adding a couple points to your score. There are a couple tricks and techniques to make your spinners spin quick and long.

First, disassemble the spinner and clean all gunk off the support wires. The cleaner a part is in general the smoother it will operate. Polish the contact points of the support wires with 200 grit sandpaper and a metal polish such as Brasso, or even Novus 2 (a plastic polish, but will work for this application). You want the support wires as smooth and round as possible. Then, using a very small round file, dress the holes in the spinner bracket so there are no rough edges both inside the hole and on the outside. Smooth is the key here.

Reassemble the spinner with one plastic disc against the spinner body, the below-playfield actuator wire, then another plastic disc towards the outside of the spinner. The discs and actuator wire shouldn't be 'snug.' There should be a little room for the wire to twist slightly if needed. The spinner should rest with a very slight forward cant, where the top of the spinner is slightly forward of the bottom. Adjust this by bending the spinner wires in the bracket by pushing up or down on the spinner flag itself. If you have the spinner adjusted perfectly perpendicular, the spinner can and will stop 'upside down' on occasion, locking the switch on.

Take some Teflon lube gel on a toothpick and put just a touch of it at the metal to metal contact point in the spinner bracket. Move the spinner back and forth and spin it to distribute the lube evenly. A simple rule of thumb with the lube is if you can see any, you used too much. Less is more here.

Adjust the switch blade so the spinner activates near the peak of its spin; you want it to kiss the stationary blade just slightly, with a very slight deflection. Another trick to consider is to change the height of the posts (or add spacers/washers) the spinner bracket rests on to raise the bracket slightly. The more to an edge the ball hits the spinner, the more energy is imparted to the spin. This is also another reason for the slight forward cant on the spinner.

A spinner can get up to 200 spins with one solid hit depending on the machine and flipper strength, well worth tweaking so it performs at its peak.

10.8 Tweaking Tilt Mechanisms

Most would ask why you would want to tune a tilt mechanism. Like it or not, tilt is part of the game of pinball. Unless you remove your tilts entirely, you want them to activate in a fair, consistent manner. There's nothing worse than playing a spirited game and tilting because a solid hit one time doesn't tilt, but yet a light hit later on tilts your ball.

Disassemble the tilt mech and clean everything really well to remove the gunk and grease. Use a metal polish such as Brasso to polish every part of the mech: The plumb bob, the wire, the brackets (both the top bracket and the round lower bracket). When you reassemble the mechanism, the position you put the plumb bob in makes a huge difference in how the tilt operates. Almost all parts manuals picture the plumb bob inverted (small side down) ABOVE the actuator ring, but almost all games have the bob BELOW the ring instead. Each position causes the tilt mechanism to behave differently.

The inverted position allows quicker recovery after a tilt; the rod stops moving quicker as the weight is closer to its pivot point. If you like your tilts tight, raising the challenge, the inverted position is the one to use as you can adjust the tilt to a hair level, but not so much that you tilt subsequent balls on a tilt. The disadvantages are that you have to remove the ring to insert the bob correctly, and that if the bob ever loosens up, it will just sit on the ring causing a non-playable machine.

The "normal" position does not have the issue just described; if the bob falls off, you end up with no tilt. Because the weight is farther along the rod, the tilt adjusted this way takes longer to recover after hits and may in fact swing for a very long time (2 minutes or more depending on the force imparted).

Regardless of the bob position chosen, you want the bob to be centered in the ring assembly. This can be accomplished by moving the ring if it has slots to do so, or by bending the hanger bracket the rod is suspended from. Sometimes you can flip the ring assembly upside down to obtain a better profile for the bob and ring to meet.

Shaking a pin is a part of the game, and possibly the greater factor in making you a better player. If you can impart force to the ball through shaking on a tight tilted machine, you will find yourself a much better player in all situations. Anyone can brute force manhandle a machine with no tilt; it takes skill and finesse to do so on a machine with a hair tilt.

10.13 Coil Sleeves

Older games used aluminum coil sleeves to guide the mechanism's plunger smoothly into the coil. The function of a coil sleeve is to reduce the distance between the solenoid coil bore and the mechanism plunger, resulting in more precise action. An upgrade that can be done to aluminum coil sleeves is to replace them with more modern nylon ones. Nylon has self-lubricating qualities that make it ideal for this usage. No lube should ever be used on any solenoid plunger. It will just gum up over time and cause weak mechanism response and a nice mess for the next person to clean up. Any machine with lube used in the past on its plungers should have the mechanisms disassembled, its metal parts cleaned with brake cleaner or isopropyl alcohol, and reassembled with a new nylon sleeve cut to the proper length.

To cut nylon coil sleeves to length use a junker plunger in the center and a pipe cutter (available at most hardware stores). Tighten the cutter a little at a time to ensure the smoothest finish possible on the coil sleeve; don't try and make the cut in one go as that will result in a rough edge to the sleeve. Smoother is always better in a mechanism employing solenoids and plungers. File off and dress any sharp metal edges on a plunger that could snag the coil sleeve as it moves in the solenoid.

10.14 Connectors and Soldering

Anytime an electrical part of a machine has intermittent operation suspect any connectors in its power chain. Any connector in a power chain at its best adds a minute amount of resistance to the power flow. Jones plugs' connectors can be cleaned and polished on the older EM machines; newer solid state machines you can try and polish the pins, but the best thing to do is replace or eliminate the connectors if you can and they are causing problems.

Often on solid state boards the male header pins crack from usage fatigue. Resoldering the header pins will fix this issue and while it's not strictly necessary to replace the header pins, it wouldn't hurt either. Tug on and inspect all connectors to ensure the wiring is crimped tightly into the pin. Any loose wires should have their pins replaced with new properly crimped pins. Do not use solder on a crimped pin connector; it changes the temper of the connector pin which allows oxygen to penetrate the wire bundle, allowing oxidation.

If you have some microswitches that use a spade connector, consider removing the connector and soldering the wire directly to the lug. The spade connectors were used on the wiring harnesses at the factory to speed production, not for any reliability concerns. Any connector added to a circuit introduces an unnecessary possible failure point. Any trouble shooting involving a circuit with a connector should have its connectors inspected very carefully as a first step.