Left: A bussed resistor network. Right: An isolated resistor network.

Here are the different resistor networks used in the system 11 switch matrix:
• SR11: 560 ohms x 8, bussed, used for the switch returns (rows).
• SR14: 3.3k ohms x 8, bussed, used for the opto switch returns (rows).
• SR9/SR10/SR12/SR13: 1k ohms x 4, isolated, used for the switch returns (rows).
• SR15: 4.7k ohms x 8, bussed, used for the switch drives (columns).

When testing a BUSSED resistor network, first find pin 1. This pin will have a white square around it, to isolated it from the rest of the pins. Use a DMM set to ohms, and put one lead on pin 1. Put the other lead on each pin 2 to 9. The same reading should be seen for each pin 2 to 9.

When testing an ISOLATED resistor network, put the DMM leads on the two adjacent pins furthest to the right or left, and note the reading. Then move both DMM leads down one pin. The same value should be seen. Continue down the resistor, moving both DMM leads one pin at a time, until all adjacent pins are tested.

A bussed resistor network. Note the white square around pin 1; this is the common pin.

A "hacked" bussed resistor network. If the correct resistor network can not be found, this shows how to make a bussed resistor network from individual resistors. Note the white square around pin 1; this is the common pin. This picture shows quite well how a bussed resistor network is wired.

Replacment resistor networks can be purchased from Digikey (http://www.digikey.com/). Below are the part numbers:
• 1k x 4 issolated (4 elements): Q4102-ND
• 1k x 8 bussed (9 elements): Q9102-ND
• 4.7k x 8 bussed (9 elements): Q9472-ND
• 560 x 8 bussed (9 elements): Q9561-ND
• 3.3k x 8 bussed (9 elements): Q9332-ND

Bad Switch Column: How to Fix it.
Usually the switch column transistors fail here. These are 2N3904 transistors at Q42 to Q49. See the Checking Transistors section for details on testing these transistors. Right before the transistors there is a capacitor network; this rarely fails (and is not documented in the list below). Next each one of the eight transistors connects to a 1.5k resistor at R71 to R78. Then the resistors at R71 to R78 connect to a resistor network at SR15. This is a group of eight separate 4.7k ohm resistors, in a single package. Measure the resistance between pins 2 to 10 of SR15, and pin 1 of SR15 (the common pin). You should get 4.7k ohms for each connection:

• 1J8 pin 1, to Q45, to R77, to SR15 pin 2, to U40 pin 18 (column 1).
• 1J8 pin 2, to Q49, to R78, to SR15 pin 3, to U39 pin 3 (column 2).
• 1J8 pin 3, to Q44, to R75, to SR15 pin 4, to U39 pin 16 (column 3).
• 1J8 pin 4, to Q48, to R76, to SR15 pin 5, to U39 pin 5 (column 4).
• 1J8 pin 5, to Q43, to R73, to SR15 pin 7, to U30 pin 14 (column 5).
• 1J8 pin 6: KEY
• 1J8 pin 7, to Q47, to R74, to SR15 pin 8, to U30 pin 7 (column 6).
• 1J8 pin 8, to Q42, to R71, to SR15 pin 9, to U30 pin 12 (column 7).
• 1J8 pin 9, to Q46, to R72, to SR15 pin 10, to U30 pin 9 (column 8).
If the transistors and resistor network checks out good, next replace chip U40 (74LS244). If there is still a switch matrix column problem, replace the PIA at U38 (6821) last.

Bad Switch Row: How to Fix it.
First check the 560 ohm resistor network at SR11. This is a group of eight separate 560 ohm resistors, in a single package. Measure the resistance between the pins 2 to 10 of SR11, and pin 1 of SR11 (the common pin). You should get 560 ohms for each connection. Then check the 1k ohm SR10 between the SR11 pin and the stated pin on U39/U40 below. You should get 1k ohms for each connection:

• 1J10 pin 1, to SR11 pin 2, to SR10 pin 1, to U39 pin 12 (switch row 8).
• 1J10 pin 2, to SR11 pin 3, to SR10 pin 3, to U39 pin 8 (switch row 8).
• 1J10 pin 3, to SR11 pin 5, to SR10 pin 5, to U39 pin 2 (switch row 6).
• 1J10 pin 4: KEY
• 1J10 pin 5, to SR11 pin 6, to SR10 pin 7, to U39 pin 5 (switch row 5).
• 1J10 pin 6, to SR11 pin 7, to SR10 pin 2, to U30 pin 13 (switch row 4).
• 1J10 pin 7, to SR11 pin 8, to SR10 pin 4, to U30 pin 9 (switch row 3).
• 1J10 pin 8, to SR11 pin 9, to SR10 pin 6, to U30 pin 2 (switch row 2).
• 1J10 pin 9, to SR11 pin 10, to SR10 pin 8, to U30 pin 6 (switch row 1).
If the resistor networks check out good, next replace either U39 and/or U30 (a 4011 chip) (depending on which switch row number is dead). If you are still having a switch matrix row problem, replace the PIA at U38 (6821) last.

Further Diagnosing of the Switch Matrix.
If you are having a switch matrix problem, the first plan of attack is to do the above column and row switch matrix tests. If these tests pass, the problem most likely is in the wiring. Note most switch failures show as Row failures (even though it could be a column problem). Here are eight different ways the switch matrix can fail. All require you use the internal "switch level" or "switch edge" tests of the game.

1. Switch column shorted to ground.
   When a column wire is shorted to ground, and any switch in that column is closed, the switch test will show ALL switches in the ROW of the closed switch as being closed. If no switches are closed, the switch test will show no switches closed. To find the location of the short, go to the end of the switch column wire on the playfield (the switches are "daisy chained" together for an entire column or row). Then break the daisy chain one switch at a time until the short no longer shows in the switch test.
2. Row shorted to ground (diode anode).
   When the anode (non-banded end of the switch diode) is shorted to ground, the switch test will show the entire row as activated (whether any switches are closed or not). To find the location of the short, go to the end of the switch row wire on the playfield (the switches are "daisy chained" together for an entire column or row). Then break the daisy chain one switch at a time until the short no longer shows in the switch test.
3. Row shorted to ground (diode cathode).
   When the cathode (banded end of the switch diode) is shorted to ground, that switch's entire row will show as closed in the switch test (whether the switch is open or closed). To find the location of the short, go to the end of the switch row wire on the playfield (the switches are "daisy chained" together for an entire column or row). Then break the daisy chain one switch at a time until the short no longer shows in the switch test.
4. Column wires shorted together.
   When two column wires are shorted together, and none of the switches in those columns are closed, the switch test will show no problems. But pressing any switch in either column will show that switch, along with a switch in the column that is shorted on the row of the switch you are closing. For example, if column 2 and column 4 are shorted together, closing switch column 2 row 3 will also show a closed switch in column 4 row 3.
5. Row wires shorted together.
   When two row wires are shorted together, and no switches are closed, the switch test will show no closed switches. When any switch on either row is closed, another switch on the same column as the closed switch will also show as closed. For example, if rows 1 and 4 are shorted, closing a switch in row 1 column 3 will also show a closed switch on row 4 column 3.
6. Column and row wires shorted together.
   When a column and row wire are shorted together, the switch test will show the switch that is at the intersection of the row and column as being closed, even though it is not closed. All other switches on all other rows and columns will work correctly. For example, column 1 and row 3 are shorted together. The intersection of this column and row will show that switch as closed (even if it's not). And remember, this switch is not what is causing the problem!
7. Open diode on a switch.
   An open diode on a switch will cause only that switch not to work.
8. Shorted diode on a switch.
   A shorted switch diode will show no problems when only that switch is opened or closed. However if additional switches in that row or other columns are closed, false switch readings can be shown.

Switch Maintenance.
Here are the procedures for maintaining your WPC switches:

• Micro-switch: no maintenance required. Can adjust the actuator arm only by rotating the switch in its bracket. Do not BEND the activator arm! Loosen the two screws holding the switch, and rotate the switch to adjust the activator arm. Re-tighten the screws, but not too tight as it will bind the switch mechanism.
• Blade or Leaf switch: clean with a business card inserted between the contacts. Squeeze the contacts closed, and remove the business card. Do not use a file on these gold plated contacts! Re-adjust the contact spacing for correct operation.
• Opto switches: use a Q-Tip and some Windex. Dip the Q-tip in the Windex, and clean the opto's two LED's (receiver and transmitter) with the Q-tip.

What is that loud "Popping" when I turn my Game On?
"I have this problem when I power-on my game; the free game knocker 'pops' with a loud knocking 4 or 5 times, then finally stops and the game starts up and does appear to play correctly. I get a message at the beginning when this happens to 'adjust switch outside loop' and #35 shows up in my fourth player score display."

What the game is trying to tell you is that switch #35 has not been actuated (ie: closed) in about 30 games or so. That's usually sufficient reason to suspect that the switch as bad. The game will do its best to compensate for the bad switch (by using other switches around it), but it is trying to say that the switch needs to be looked at.

Inside the coin door there should be three operator diagnostic test switches. Make sure the middle one is in the "Down" position, and then press the one marked "Advance" or "Enter". This puts the game in Test mode. Keep pressing Advance until you see the "Switch Edges" test (remember at this point the playfield is "live", so watch those pop-bumpers, slingshots and flippers). Now verify that the bad switch really doesn't work by activating it. Test it using the ball if possible and not just your hand.

Now turn the game off and remove the balls and lift the playfield. Locate the switch under the playfield. There should be a bunch of "blade" (or possibly micro) switches. The one that doesn't work may have a broken wire, or some other sort of mechanical failure. If it is a leaf switch, it may simply be dirty. Find a business card and gently press the switch leafs closed, and pass the card between the two contacts. These switch contacts should be gold flashed, so don't use anything abrasive (the business card is all that is needed).

The leaf switch could also be out of adjustment. There is one moving blade, and one stationary blade. To adjust the switch, bend the *stationary* blade only to move the switch contacts closer. Test the switch with a ball to make sure it is working correctly.

If the game has microswitches, a simple adjustment to the activator arm may be in order, or the switch itself has failed.

Test the switch again in switch test, and see if this solves the problem. If it doesn't, check for a problem with a broken wire on a nearby switch. The switch wires "daisy chain" from switch to switch in the same row/column. So a non-working switch could be a broken wire "upstream".

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3L. When thing don't work: Infrared Optic Switches (Drop Target switches)

Williams also used optic light emitting diodes (LED's) for some switches, even on the older System 11 games. Mostly Williams used "U" shaped optics for detecting the position of drop targets. The problem with this is vibration. Often the optics will actually break off the circuit board because the drop targets take so much abuse.

The optic board from a pre-system 11b drop target (note the lack of any chips on this board). You can use Radio Shack's infrared detector card to see if the opto transmitters are working. On these older optics, the "red" side is the transmitter, and the "white" side is the receiver. The transmitter is the side that 95% of the time dies. After all, it's essentially a light bulb that can burn out.

If a drop target is not sensing when it is down, it's a good chance you have an optic problem. The optic board is held to the drop target with three "E" clips on rubber mounts. Remove the "E" clips and the board will lift off the drop target assembly. Now inspect the optics. If they are not broken, clean them with a Q-tip dipped in Windex. It is amazing how often just cleaning optos in this manner fixes them.

Optos have two sides to them: a transmitter, and a receiver. The transmitter is the part that fails 95% of the time. Essentially the transmitter is a light bulb, and all light bulbs burn out eventually. And the optics are always "on", even when the game is in attract mode (another good reason to turn your game off when not in use).

A nice tool to have in your tool box is the Radio Shack infrared detector card. This $5 credit card sized card will show if the optic transmitter is producing light. Without this card, you can not see this wave length of light. So this handy little card is quite good to have. Remember you must have the card positioned in front of the transmitter to see the light on the orange colored band (having it in front of the receiver won't show anything!). The "red" side of the "U" shaped opto is the transmitter side of the optic.

System 11b and Later Optic boards.
With system 11b, the optic circuit was removed from the CPU board. This meant that the optic board (for example on drop targets) needed added circuitry to do the switch processing. This was done by adding LM339 chips to the optic board. If you are having problems with an optic board, and you know the optics themselves are good, suspect the LM339 chips. These are inexpensive chips; just replace them wholesale on the optic board if in doubt.

New Style Optics on Optic boards with LM339 Chips.
The optics themselves were changed on the newer optic boards with LM339 chips. The new optics used new style "U" shaped optics (as used in the 1990 and later WPC games). Unfortunately this new style of optics had a much bigger problem with breaking leads, and falling off the optic board. Whenever replacing these optics, put a dab of silicone underneath the optic when mounting them to help prevent this problem.

Replacing the Optics.
Be careful installing new optics. It DOES matter which way you install them! If you install the new optic backwards, you will probably ruin it. Remember on the old style optic boards, the red side of the optic is the transmitter. On new style optics, the side of the optic with the white "dot" or the "notch" is the receiver. The white dot on these new style optics matches with a corresponding white dot on the circuit board, to make installation easy. Also use a dab of silicon under the optic when mounting them. This will give them some shock resistance.

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3m. When thing don't work: Score Display Problems

One of the most frequent system 11 problems relates to non-working or weak score displays. Fortunately, often there is a very easy fix for this problem.

The simplest thing to check when the score displays do not work is the +100 and -100 volt DC power section of the power supply. If either of these voltages are bad, your displays will not work. And quite often, this power supply section does go bad.

The 39k ohm Power Supply Resistors.
The major villain in the system 11 power supply is resistors R1 and R4. These are both 39k ohm, 1 watt resistors. Very often either or both of these resistors will go out of spec, or even completely open. This will prevent the +100 and/or -100 volts from getting to your score displays On newer WPC games with alphanumeric displays, these are resistors R48 and R49 on the alphanumeric display board.

Note the score display is barely working. At first, you may think it's the display glass itself. This is infact a common problem, where the displays "outgas" and don't show as brightly, and eventually completely die. But before you change the expensive score display glass, change the 39k ohm resistors on the power supply with new 1 or 2 watt "flameproof" resistors.


Here is the same score display after the 39k resistors were changed on the power supply board. This cheap 50 cent fix shows that the score display glasses themselves were good!


If your high voltage fuses are not blown, and your score displays do not work, first replace the 39k ohm resistors. These are cheap and easy parts to replace (a lot cheaper and easier than replacing score display glass!). Or at least check these. Replace these two resistors with "flame proof" 1 or 2 watt 39k ohm versions. And make sure you mount the new resistors slightly off the circuit board, so air can get under them for cooling.

Check the +100/-100 volts at the Power Supply board.
It's really easy to check the +100 and -100 volts at the power supply board. These voltages should be from 95 to 105 volts. Check for these voltage at power supply connector.

Power Supply D-8345-xxx (where xxx is the game number). Used from High Speed to Swords of Fury ??.

• 3J5 pin 1: ground
• 3J5 pin 3: -100 volts DC
• 3J5 pin 4: +100 volts DC
• 3J5 pin 6: +5 volts DC

Power Supply D-11883 and D-12246. Used from Taxi ?? to Doctor Dude.

• 3J2 pin 1 (orange): -100 volts DC
• 3J2 pin 3 (brown): +100 volts DC
• 3J2 pin 5 (black): ground
• 3J2 pin 6 (gray): +5 volts DC

WPC AlphaNumeric Display Board. Used on Funhouse, Harley Davidson, the Machine.

• J307 pin 1: input +100 volts DC
• J307 pin 4: ground
• J306 pin 1: +5 volts DC
• J306 pin 3: ground

Power Supply Diodes Leak.
Like resistors the two 39k ohm resistors, the two diodes at D1 and D3 (1N5990) can start to "leak" (on WPC alphanumeric games, diodes D1 and D2 on the alphanumeric display board). If your displays are weak and your 100 volt section is low (even with the score display glass unplugged), try changing these two diodes (after you change the 39k ohm resistors first).

Blown high voltage score display Fuse(s) in the Backbox.
Every system 11 game at least one fuse to protect the +100 and -100 voltages which power the score displays. Later games have more than one fuse. These are located in fuse holders in the backbox. If these fuse(s) are blown, try replacing them, and power the game back on. If they blow again immediately, you will probably need to rebuild the high voltage section of the power supply board.

Also a blown UDN7180 chip on the master display board can cause the high voltage fuse(s) to blow on the power supply board. These chips can short the +/- 100 volts directly ground, and blow the fuse.

Increasing Score Display Life.
Glass score displays are getting very expensive. Because of this, it is important to make your current glass score displays last as long as possible. The best way to do this is to decrease the 100 volts (which powers the displays) to 91 volts. This can be done by replacing the zener diodes at ZR2 (Z2) and ZR4 (Z4) to a lower voltage diode

The original diodes used at ZR2, ZR4 are 1N4764A. These are 100 volt, 1 watt zener diodes. If you replace these with 1N4763A diodes, which are 91 volt, 1 watt zener diodes, only 91 volts (instead of 100 volts) will power the displays. This will make your displays slightly less bright, but it will also DRAMATICALLY increase their life span! Since glass score display tubes are becoming so expensive, this is highly recommended. Note on the newer WPC alphanumeric games, diodes D5 and D6 were changed to 1N4763 diodes from the start.

The high voltage section of the power supply.

Rebuilding the 100 volt Power Supply Section.
If any of the high voltage fuses are blowing, you probably need to rebuild the 100 volt power supply section. You will need to replace the following parts on the power supply board.

Positive System 11 100 volt section parts to replace:

• Q1 = MJE15030 transistor. On older games that specify a SDS201 transistor (which is no longer available), the leads of the MJE15030 transistor must be "twisted" so the emitter, base and collector match the circuit board. You can also use a MJE340 (NPN 300 volt transistor) or a 2N3440 with a "star" heat sink.
• Q2 = 2N5401 (PNP 150 volt transistor).
• Z1 = 1N4730A (3.9 volt 1 watt diode).
• ZR2 (Z2) = 1N4764A (100 volt, 1 watt) diode. Use 1N4763A (91 volt, 1 watt) diode instead (to increase score display life).
• R1 = 39k ohm, 1 or 2 watt flame proof resistor.
• R2 = 680 ohm, 1/2 watt resistor.
• R3 = 330k ohm, 1/2 watt resistor.
• C2 = 0.1 mfd 250 volt metal polyester capacitor.

Negative SYstem 11 100 volt section parts to replace

• Q3 = MJE15031 transistor. On older games that specify a SDS202 transistor (which is no longer available), the leads of the MJE15031 transistor must be "twisted" so the emitter, base and collector match the circuit board. You can also use a MJE350 (PNP 300 volt transistor) or a 2N5416 with a "star" heat sink.
• Q4 = 2N5551 (NPN 140 volt transistor).
• Z3 = 1N4730A (3.9 volt 1 watt diode).
• ZR4 (Z4) = 1N4764A (100 volt, 1 watt) diode. Use 1N4763A (91 volt, 1 watt) diode instead (to increase score display life).
• R4 = 39k ohm, 1 or 2 watt flame proof resistor.
• R5 = 680 ohm, 1/2 watt resistor.
• R6 = 330k ohm, 1/2 watt resistor.
• C4 = 0.1 mfd 250 volt metal polyester capacitor.

A replacement MJE15031 in an older system 11
power supply. The leads on the MJE15030 and
MJE15031 must be "twisted" to replace the
older SDS201 and SDS202 transistors. This should
ONLY be done on power supplies that originally
used the older SDS201 and SDS202 transistors.

When installing the new parts, cut the old parts out first. Then use a solder sucker and clean out the circuit board holes. Make sure you install new resistors slightly off the board, to allow for air circulation. Solder all parts on both sides of the board.

When installing the newly fixed board, measure the output voltages BEFORE you plug in the connectors going to the score displays! Output voltage should be between 95 and 105 volts.

Score Display Ribbon Cable Problems.
System 11 and WPC alphanumeric games have a fairly small problem that can appear to be a major one. If you have had the CPU board out of your game, and now your score displays don't work, check the ribbon cables connecting to the CPU board. It is very easy to install the cables offset by 1 pin to the left or right. In most cases this will not damage the electronics. And always make sure the red strip on the edge of the cable lines up with pin number one on the CPU board connector.

Slow Display Strobing Problems.
Sometimes the score displays can have a slow reveal and wipe pattern that leaves only three or four digits on at a time. This can show as three or four digits in the player one and three displays, then the credit display, and finally the player two and four displays. Then the next three or four digits display the same way across all the score displays. You never see the entire display lit. The game will do this in game or game over mode, just repeating the pattern. The score displays do however keep score accurately. Also this problem can sometimes be seen in a single score display.

This is usually caused by weak high voltage going to the score displays. Instead of plus or negative 100 vdc, the voltage can be as low as 50 volts. This low voltage can be caused by resistors R1 and/or R4 (39k ohms) on the power supply board, or a bad high voltage capacitor C1/C3 (100 mfd 250 volt), or C2/C4 (0.1 mfd 250 volt metal polyester cap) on the power supply board.

Partial Segment Failures on Score Displays.
Sometimes only parts of a display aren't displaying, and only on certain numbers. For example, the top part of a "0" or "7" are not displaying. It can even be so strange so that the missing segment will work on some numbers or letter, but not on others.

This can be caused by one of the hex input buffers at U10, U11, U15-U18 (14050 or 4050) on the Alphanumeric master display board, which are CMOS chips and static sensitive. You can check these with your ohm meter. Connect one lead to ground, and the other lead to each input/output pin of the 4050 chips. Any pin that doesn't read the same as the others probably means the chip is bad. Sometimes you'll have to test these chips with an analog ohm meter, and watch the needle "bounce". A pin that doesn't "bounce" like the others again probably means that chip is bad.

More Segment Problems: the UDN7180 chip.
If you are having display problems (and you have fixed the power supply board), the next course of action is to check the UDN6118 and UDN7180 chips on the Master display board. The UDN6118's control the strobe pulses, and the UDN7180 control each segment in the display. Usually the UDN7180 is the one that fails (and are unfortunately hard to get and somewhat expensive). There are as many as four UDN7180's and UDN6118 chips on the master display board.

Both these chips are easy to test: both have an input and output side. If the input side is pulsing (check this with your logic probe), then a good signal is probably getting to the chip. Next check the output side. It should be pulsing too. To test these, put the game in it's diagnostic display test. Then single stepped to the next digit test (all zeros, 1's, 2's, etc) and check the input and output pins at each step. If the input side is pulsing, and the output side is not, then the chip is probably at fault.

The UDN6118 and UDN7180 both have the same pinout: pins 1 to 8 are the input side of the chips, and pins 11 to 18 are the output side. Check the schematics to see exactly which chip controls which display when diagnosing these. Here's an example:

Problem: segment 'b' (top right) always on for players 1 and 2, and ball-in-play score display (but not credit display!).

Answer: looking at the display board schematic found that U13, U14 (UDN7180) are common components to these displays. Chip U13 drives segments "h,j,k,m,n,p,r" and the period, while U14 drives "a" to "g" and the comma. Since UDN7180's are becoming rare and are expensive, the input and output signals were double checked by comparing them with a logic probe (or an oscilloscope). Putting the game in display test so it could be single stepped to the next digit test (all zeros, 1's, 2's, etc). On chip U14, the input pins 1-8 showed activity and changed when I advanced to the next digit test. Next tested the U14 output pins 11-18. The output pin 18 (for the "b" segment) was constant and did not change when the test was advanced. The conclusion was to removed and replace the UDN7180 at U14 (after installing a socket), which fixed the problem.

Segment Still doesn't work: Check the Resistors before replacing a UDN7180.
Since UDN7180 chips are expensive and hard to find, you want to make sure it really is the problem before you replace any. If you have checked/replaced the 4050 chip(s) and probed the UDN7180 and UDN6118 chips, there is one more thing you should check. That would be the resistors coming off the UDN7180 chips. Though it doesn't happen a lot, a bad resistor solder joint or bad resistor itself could be your problem.

Check these resistors with your multi-meter to make sure they are at the correct value. Using the schematics, find the segment letter identifier you are missing. Then follow that segment through the UDN7180 and its corresponding resistor. Make sure that resistor is within 10% of the schematics specified value. Or if you don't have a schematic, just check ALL the resistors on the Master display board with your multi-meter. The slightly larger 1/2 watt resistors tend to be the more troublesome resistors.

"Outgassed" Score Displays.
Score display glass has a limited life; it does not last forever. Time will eventually kill these, and the display will "outgas" and fail. Because of the high voltage involved with score displays, the anode and/or cathode inside the diplay glass breaks down. This results in the "outgassing" of impurities that eventually change the internal gas properties, so the display can't glow (the gas must be very pure for the display to work). There is no fix for this short of replacing the display glass (which have become fairly expensive now). Sometimes score glasses short too.

Two Versions of the Alpha-Numeric Display Boards.
Taxi and Police Force use a slightly different style of display board. Both these games have an extra score display. In order to accomodate this, the standard system11 alpha-numeric display board was modified slightly.

Taxi and Police Force have an alpha-numeric display at the top, and an alpha-numeric display which is only used for numerics on the bottom in the backbox. The reason for this is that when they installed the extra display they needed a way to run it. The bottom 16 digit display on these games only uses 8 segments (the middle segment of the display is used to make the number zero into an eight, which is two segments). This leaves six segments and the "comma" left unused. The unused segments are then used to drive the extra display. This is the reason there's a second place to hook up a ribbon cable on the Taxi/Police Force display boards.

The Taxi/Police Force style display board can be converted to work in the other 16 digit alpha-numeric system 11 games, with a small modification. Simply install the missing seven resistors into locations R62 to R68 on the Taxi/Police Force display board.

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3n. When thing don't work: "Factory Setting" or "Adjustment Error" (Battery Problems)

Often when you buy a used system 11 game, upon power up, you'll get an error message stating, "Adjustment Error" (if the coin door is closed) or "Factory Setting" (if the coin door is open). This message indicates that the CPU RAM chip at location U25 on the CPU board has forgotten the game's bookkeeping and options settings.

If the coin door is closed, and the batteries are dead, you'll get an
"adjustment error" message.


If the coin is open, and the batteries are dead, you'll get a
"factory setting" message. You can also get either above message
if the battery holder is bad, or the RAM chip at U25 has failed.


The difference between these two messages is simple; when the coin door is closed (and the memory protect switch which is connected to the coin door is pressed in), the CPU is electrically blocked from accessing the RAM at U25. Therefore the game can only reset the factory settings if the coin door is open. If the game ever comes up with the "Adjustment Failure" message, the coin door must be opened to get past this message.

Why Do I Get These Error Messages?
Most often, these errors occurs because the three "AA" batteries on the CPU board have died. These batteries should be replaced every year with good quality alkaline batteries (batteries are cheap, battery damage is expensive). The three batteries must keep at least +4 volts of power to the U25 RAM chip for it to remember. When power goes below +4 volts, memory reset can occur (and you get the "Factory Setting" error message).

A bad battery holder. At first glace, this holder looks fine. But the two battery contact points on the left have corroded and fallen off. The contact on the right is the only one intact. These contact points are actually rivets, but corrosion will cause the face of the rivet to break as it goes through the fiber insulator, and the face of the rivet that contacts the battery falls off.

The Battery Holder: a Weak Link.
If after replacing the batteries, you still get a "Factory Setting" error, suspect the battery holder. Use your DMM and check the battery voltage at the CPU board. With the game off, put your DMM on DC volts and put the black lead on ground (the grounding strap or on one of the screws holding the CPU board in place). Put the red lead on each of the CPU board's POSITIVE battery terminal SOLDER POINTS. Test each of the three batteries' positive leads individually. You should get about 1.5, 3.0, or 4.5 volts at each battery (note the batteries are additive and the first battery in the chain will give you 1.5 volts, and the last battery will give you 4.5 volts). If you don't these positive voltages, suspect damaged battery holder terminals. These corrode quite often if new batteries aren't installed religiously. Replace the battery holder and re-test to ensure proper repair.

A battery gone bad. Note the white "fur" on the bottom of the battery, and how it has corroded the chip and socket below it. The battery holder, chip and socket must all be replaced. Also the board must be washed with a mixture of 50/50 water and white vinegar (a mild acid) to neutralize the alkaline battery gunk, and then rised with water. After drying, the corroded areas can be sanded clean to the bare copper traces, and the components replaced. If the board isn't washed with this vinegar solution, the corrosion will return.

A Better Replacement Battery Holder.
The best battery holder to buy is the new black plastic battery holder used in WPC-S and later games. This is Williams part# A-15814. This design of battery holder is much better than the original system 11 design, and will fit perfectly on a system 11 CPU board.

Testing for Battery Voltage.
After testing the batteries at the battery holder, test for voltage at the blocking diode D2 (1N4148), which is next to the left bottom side of the battery hold on the CPU board. With the game off, put the black lead on the backbox ground strap, and put the red lead on either side of the diode. You should get around 4.2 to 4.8 volts. The banded diode of the diode connects to the U25 RAM chip pin 24, and should be about .5 volts less than the non-banded side of the diode. If you only get voltage on only one side of the diode (the non-banded side, which connects directly to the battery), the diode is bad and needs to be replaced.

Next check for voltage at the U25 RAM chip. With the game off, you should get about 4.3 volts DC at pin 24 of chip U25 (ground is pin 20 by the way). If you don't, the battery voltage is not getting to the U25 RAM chip. This will cause the game will boot up with the "Factory Setting" or "Adjustment error". Note pin 24 of the 24 pin RAM chip is in the same position as pin 1 of the chip, but on the opposite row of pins. Pin 1 is designated with an impressed "dot" right on the top of the chip. This chip is a 2k by 8 CMOS static 24 pin RAM chip. The part number will be 2016 or 6116-L or NTE2128. Early system 11 games specify this chip as a 5177, but this chip can be replaced with a 6116 instead.

You can still have problems even if you installed new batteries and all the voltages check out. If your game is still giving "Factory Setting" or "Adjustment error", you may have a bad CPU U25 RAM chip. But make sure you double check that battery holder. Even minor corrosion can cause this problem. The voltages may all check out, but the corrosion may be enough to limit CURRENT, and cause this problem.

More "Blocking" Diode D2 Problems.
The three AA batteries are connected to the U25 RAM chip via a "blocking" diode. This 1N4148 switching diode at D2 is connected in series between the battery and the U25 RAM chip. It's job is to prevent +5 volts from going back to the batteries (it only allows power from the batteries, not to them). Sometimes this diode shorts out or goes open. If this diode shorts, the CPU board will try and charge the three AA batteries! This will cause the batteries to leak, and could damage your CPU board. If the diode goes open, the batteries will never power the U25 RAM chip, and the game will boot up with the "Factory Setting" or "Adjustment error". Check this diode with the game off and your DMM set to the "diode" setting. You should get between .4 and .6 volts in one direction, and a null reading in the other direction. You can also test the diode (with the game off) by setting your DMM to DC volts. Put the black lead on ground, and you should get 4.2 to 4.8 volts on either side of diode D2 (the banded side will be about .5 volts higher). If you only get voltage on one side, the diode is open and needs to be replaced.

Changing Batteries.
If your game is working, and it's time to replace the batteries, follow this procedure. But the way, you should change the batteries in your game every year, or every two years at most (to prevent any battery leakage problems):

• Remove the backglass and gain access to the CPU board.
• Turn the game ON.
• Note the orientation of the installed batteries (All positive terminals up or to the right?).
• Remove the old batteries and discard.
• Check the battery holder's terminals for any corrosion. Clean with 220 grit sandpaper if any corrosion. If damaged, turn game off and replace battery holder.
• Using a Sharpie pen, write today's date on the new batteries.
• Install the new batteries.
• Turn the game off.

If you install new batteries with the game turned on, the machine will not forget the old option settings or bookkeeping totals.

Clearing a "Factory Setting" or "Adjustment Error" Message.
To clear these messages, you first need to fix the problem (replace the batteries and/or battery holder, replace the U25 RAM, etc.). After this is done, turn the game on. Then press the center red coin door button into the down position. Now press the black button closest to the coin door. If you have an "adjustment error", the game will beep and flash the "factory setting" message.

Once you have the "factory setting" message, press the black button closest to the coin door twice. Then move the center red button to the up position. Then press the black button closest to the coin door again (twice if you had an "adjustment error" message). The game should now go into attract mode.

New CPU Batteries Die very Quickly.
Just to the side of the battery holder on the CPU board, there are two "blocking" diodes, D1 and D2. These form a diode bridge, blocking the battery voltage from the power supply, and vice-versa. Where these two diodes meet, power goes to the U25 RAM. This way when the game is on, power for the U25 RAM is drawn from the power supply. But when the game is off, power for the U25 RAM is drawn from the batteries.

If either diode D1 or D2 is bad, it can let the batteries attempt to power all the +5 volts logic for the whole CPU board when the game is powered off. Or it can let the +5 volts from the power supply attempt to charge the batteries when the game is powered on. In either case, this will cause the batteries to die quickly.

If you have batteries that are dying very quickly, replace both diodes D1 (1N5817) and D2 (1N4148) on the CPU board.

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3o. When thing don't work: Miscellaneous Oddities

Problem: In attract mode, the pop bumper coil on my F-14 behaves normally (did not fire or energize). Once a game was started or test mode entered, the coil would fire and stay energized. In attract mode, the coil could be fired by hitting the pop bumper skirt switch (this is NOT normal behaviour, and the others pop bumpers did not work this way)! Grounding the metal tab of the Q69 TIP122 transistor while the game was in attract mode energized the coil and released it (properly).

Answer: A close look at the 7402 chip at U50 (which is the controlling TTL for this coil) revealed that pins 5 and 6 where shorted together. This was caused by a solder splash from a previous repair. Removing this short fixed the problem!

I turn my system 11 game on, and the score displays will only show 0's and X's in the middle of them.
Problem: the game thinks you have "slammed" it.

Answer: there is a slam switch inside the coin door, just above the coin door lock. This switch should be normally open. If this switch is shorted or bent closed, you will have this problem. Often people will accidentally bend this switch when putting credits on the game (a good reason to have the game set on free play!). If the switch is not shorted closed, the switch matrix could also be damaged, as the slam switch is part of the switch matrix. See the Switch Matrix section of this guide for info on fixing that.

A system 11 game coil is always energized.
Problem: "I have a system 11 game with solenoid problems. I have replaced the TIP122 transistor, the associated pre-driver transistor, the 7408 chip, and even the 6821 PIA. But nothing keeps the solenoid from staying energized."

Answer: some 50 volt coils are driven by a TIP36 transistor on the Auxiliary power driver board. If the TIP36 is shorted, the coil will stay energized (regardless of what you replaced further up the electronic river).

"When I turn my Fire! game on, the score displays would flash quickly at a high brightness, and the speakers would be noisy, but the game does nothing more."
Problem: the CPU board has a blanking circuit problem. The job of the blanking circuit is to shut down the score displays, solenoids and lamp circuits if there is a problem on the CPU. This safety circuit also protects other circuits during power-on if there is a problem.

Answer: there were two failed components, a 555 timer chip at U43 and a bad 2N4403 transistor at Q50.

To test the blanking circuit for proper operation, check U20 pin 2 or U43 pin 3 at power-on, using a logic probe. You should get an initial LO for a few seconds, followed by a continuous HI after the game has booted.

All score displays are out, game will start but flippers and ball eject do not work. While the game was being played (when it worked) the displays began acting strangely then the game died. Any further attempts to start a game resulted in above problems.

Answer: Examining the display board discovered a glob of flux on U11 (4050 hex buffer) shorting pins 14 and 15 together. Using the schematics and wiring diagrams was able to trace those pins back to the CPU board. The short killed U51 (PIA 6821) on the CPU board. Removed U51 (6821), added machine pin socket, and replaced it with a new 6821 PIA.

"No Sound on my Pinbot."
Problem: The sound on the Pinbot just suddenly died. The amplifier section seems to work, because when the volume control is turned, you can hear the scratching sound coming from the speakers. Also when the sound test button is pressed on the CPU board, you can faintly hear the sounds.

Answer: No -12 volts DC, which is used for the sound. In this case it ended up being the bridge rectifier that converted the 12 volts AC to DC voltage that had failed.

When the flipper button is pressed, the game resets. When the ball hits the slingshot, the game tilts.
Problem: This is a switch matrix problem. The low voltage (high score) switch on the flippers and the slingshot scoring switch are triggering other switches in the switch matrix.

Answer: First I would suggest looking for a bad, missing or mis-wired switch diode. But in reality this was not the problem. A switch matrix column transistor (2N3904) was bad, as was the switch matrix column resistor network SR15.

The CPU software for Road Kings on the Williams web site does not seem to work.


Answer: Indeed the EPROM software for Road Kings on the Williams web site is bad. For working software, click here for working EPROM files.

On My F-14, I need a new rubber belt to drive the rotating beacon lights. Where can I get this?


Answer: This rubber drive belt is available from any local John Deere tractor store! Just ask for part number H85996, cost is about $2.00.

Left: A parallel wound FL11630 flipper coil. Note the lug on the far right is the common lug, with both the thin and thick coil winding wires attached. The center and the left lugs connect to the EOS switch (the wires going up). The two outside lugs are the power and return wires, with the gray power wire going to the right lug (the lug with the diode bands closest).
Right: The EOS switch and the 2.2 mfd 250 volt non-polarized capacitor that attaches to it.

Here are the instructions to convert an older FL23/600-30/2600 or FL24/600-30/2600 flipper coil to the new parallel wound FL11630 or FL11722 flipper coil (and add the 2.2 mfd EOS switch cap). Or here's how to just install another FL11630 or FL11722 coil in your game.
• Turn the game off and remove the FL23/600-30/2600 or FL24/600-30/2600 coil from the game. You will have to unbolt the coil stop to do this.
• Install the new FL11630 or FL11722 coil. It's best to install the coil with the solder lugs furthest away from the coil stop (but the flipper wires aren't always long enough to do this).
• Note the lug on the FL11630 or FL11722 coil with BOTH the thin and thick coil winding wires attached to it. The Band of the diodes should both be towards this lug.
• Hook up the EOS switch wires to the center lug and outside non-banded diode lug, with the thin coil winding wire attached.
• Hook up the non-polarized 2.2 mfd 250 volt EOS switch capacitor to the EOS switch lugs.
• Hook up the power wires to the two outside coil lugs. And yes it DOES matter which wire goes to which lug! The main power wire should attach to the outside lug closest to the diode bands (the common lug with both the thin and thick coil winding wires attached). This should be the same wire you removed from the old coil lug with the banded diode attached.

If you get the two outside lug power wires reversed, a 50 volt solenoid fuse will blow, and the flipper buttons will not control the flipper coils! Instead they will do something weird like turn the flash bulbs on. Just reverse the wires and install a new fuse, and you're all set to go.

The CPU Board Flipper Relay K1.
The flippers are only enabled during game play and in diagnostic mode. The flipper enable relay is what turns the ground off and on connected to the flipper coils. The flipper enable relay is located on the CPU board at K1, and is a 4P, 40 ohm, 6 volt relay. When you enter diagnostic mode, you should hear the flipper relay K1 click on (activating the flipper buttons).

EOS Switch Maitainence.
The EOS switches on all system 11 games do need periodic maintenance. Since they are high voltage switches, there is some electrical arcing. The arcing is much more of a problem on High Speed to Millionaire games with the series wound FL23/600-30/2600 flipper coils. Excessive EOS switch arcing will cause the switch contacts to pit and burn, and cause some resistance. As the resistance increases, more arcing occurs (which causes even more resistance). Eventually, bad EOS switches will make the flippers very weak. They must be filed clean with a small point file periodically. The switch contacts are made of Tungsten.

Adjusting the EOS switch.
The EOS switch should be adjusted (after filing it clean) so there is about 1/8" gap when the flipper is at full extension. Any less than that and you are asking for trouble. Any more than that and you are scraficing flipper power.

Shorting the Flipper EOS switch to the Lane Change switch.
Williams has a feature called "lane change" in many of their games. This allows the player to change the lit lanes using the cabinet flipper buttons. Prior to Banzai Run, this is done by doubling up a second switch on the flipper EOS switches. The EOS switches are a +50 volt switch. The lane change switch is a +5 logic switch connected to the switch matrix. These two switches are insulated from each other by a small nylon "triangle" activator. But if these two switches touch, the switch matrix will burn (as described above).

When adjusting or cleaning the flipper EOS switches or lane change switches, make sure the game is turned OFF. This will prevent shorting these two switches together. Also, do not clean the smaller lane change switch with anything other than a business card.

Lane Change on games with Interconnect boards.
When the interconnect board was introduced on Banzai Run, Williams stopped using a doubled up switch on the flipper EOS switches for the lane change. Instead, circuitry was added on the interconnect board using a MOC3010 opto coupler. If you have problems with the lane change on these games, replacing the small 8 pin MOC3010 opto couplers will usually fix the problem.

Flipper Rebuild Kits.
Williams sells a flipper rebuild kit that contain all the parts you would need to rebuild two flippers. It includes parts like the entire right and left flipper pawl and plunger/link assemblies, coil sleeves, coil stops, EOS switches, EOS switch capacitors (for the non-fliptronics kits), and other parts. At $20 a kit (to repair two flippers), it's a pretty decent deal because it's all the parts you'll need in one kit. But you can save some money if you just replace the parts that are worn (the plunger/link, link bushing, coil sleeves and usually the coil stops). For newer style WPC fliptronics flippers, the kit's part number is A-13524-8. For system 11 flippers, it's part number A-13524-1. The genuine Williams kits come in a cute plastic clamshell container.

Left: Flipper assembly with the coil stop (and coil) removed.
Right: The coil stop. Notice the mushroomed head on the top example. Below that is a re-worked coil stop (using a file). It is recommended replacing the coil stop rather than re-working it.
 

Measuring the coil stop with a dial caliper.
The thickness of a new coil stop is .440 inches.
After re-working, if yours is .425 inches or less,
replace it.


Rebuilding Flippers: Removing the Coil Stop.
First, use your allen wrench and remove the two 10-32 x 3/8" bolts that hold the coil stop in place. This will release the coil from the assembly. Move the coil to the side for now.

Examine the coil stop. Often, the coil stop will have a "mushroomed" head. This happens from the coil plunger slamming into the coil stop. If this is the case, replace the coil stop. In a pinch, you can re-work the coil stop and file the mushroomed head flat and bevel the edge. The problem with this is plunger travel length increases. If excessive, the plunger link will now slam into the top coil bracket, destroying it. Also the increase in plunger travel can cause the flipper pawl to hang on the EOS switch (leaving the flipper in the up position). A new coil stop is .440 inches thick. If your coil stop, after filing, is less than .425 inches thick, you should replace it. Less than .425, and you'll have problems with the flipper pawl hanging on the EOS switch. Coil stops are less than $1 each. If in doubt, just replace it!

The flipper assembly with the pawl
assembly removed. The flipper shaft can
be seen extending through the playfield,
and through the nylon flipper bushing.

Removing the Flipper Pawl Assembly.
Use your allen wrench and an open wrench, loosen (but don't remove) the bolt that clamps the pawl assembly to the flipper shaft. From the playfield side, turn and pull the flipper while holding the pawl assembly until the flipper can be pulled from the playfield. The pawl assembly can then be removed from under the playfield.

Worn Coil Bracket?
If the game was played so much that the coil sleeve wore out (thanks in part to a worn plunger link), the plunger could then come in contact with the coil bracket. This would elongate the bracket's hole. Also, if the coil stop was filed (to removed a mushroomed head) and plunger travel increased, this could ruin the coil bracket too. In either case, the coil bracket will need to be replaced.

Replace the Flipper Bushing?
The flipper bushing is a nylon part that the flipper shaft passes through. Unless it is cracked, or the flipper was very weak, or the game has more than 30,000 plays, it may not be necessary to replace this part. It's pretty easy to tell if it needs replacing. With the flipper pawl removed from the flipper shaft, wiggle the flipper on the playfields, side to side. There should be some play, but not excessive play.
When replacing the flipper bushing, remove the entire flipper bracket from under the playfield. This allows access to the three 6-32 x 3/8" bolts and nuts that hold the bushing to the bracket. These bolts have nuts on the bottom side of the flipper bracket, which can't be accessed with the bracket in place.

Left: Note the flipper link's hole has elongated. Also, the black heat shrink tubing on the pawl is very worn from activating the EOS switch. Although it doesn't look it, the flipper link spacer bushing (lower left) is also worn.
Right: Note the plunger tip has mushroomed, and there is considerable plunger pitting.
 
Rebuilding the Pawl.
The flipper pawl assembly can now be rebuilt (if you buy a whole new flipper pawl assembly with a new plunger/link for about $10, skip this section). Remove the allen bolt that holds the flipper plunger/link to the pawl. The plunger/link can now be removed (you may need to use a screwdriver to spread the pawl assembly slightly to release the plunger/link).

Top: New style, fatter and more substantial flipper link.
Middle: Old style, thinner flipper link; the preferred version for the newer style return spring set up. Since it's not as thick, it doesn't hang up inside the flipper pawl assembly as easily. It's also a more versatile link, and can be used in most Williams (and DataEast!) games from the mid-1980's and forward.
Bottom: Old style, chewed up link from a flipper plunger return spring. This is why Williams went to the newer style (top) plunger link. The plunger return spring just hacks away at the link.


Inspect the flipper link spacer bushing, which should be inside the flipper link's hole. Brand new bushings have an outside diameter of .310 inches, and an inside diameter of .090 inches. If you have a dial caliper, measure yours. If even .003" less than these values, replace this bushing. If in doubt, just replace it.

Replace the flipper plunger and link. A new plunger/link can be bought for $1.50. (rebuilding the plunger is hardly worth it. Spend the $1.50 and get a new plunger/link. If rebuilding the plunger/link is your only option, here's what to do: grind and bevel the plunger tip to remove the mushroom. Using a 1/8" metal punch, remove the roll pin that holds the link in place. Install a new link, and hammer the roll pin back in place. Make sure the new link moves freely.)

Install the plunger/link and a flipper link spacer bushing. Remember the allen bolt that holds this is place goes through the pawl assembly with the nut on the same side as the pawl (see pictures).

A new plunger/link and new spacer bushing. Note the
freshly installed (white) pawl heat shrink tubing and allen bolt.

Replacing the Pawl Heat Shrink Tubing.
The flipper pawl's job is to activate the EOS switch at the flippers' end of stroke. This metal pawl tab is factory coated with heat shrink tubing to prevent wear to the EOS switch. When the coating is worn, metal-to-metal contact (pawl to EOS switch) occurs. This will shred the EOS switch blade. When the EOS switch blade frays, it can hang-up on the flipper pawl. This will cause the flipper to stick in the up position (regardless of the condition of the return spring).

The heat shrink tubing also provides insulation between the metal flipper pawl and the EOS switch. This is especially important because the EOS switch is a high voltage switch. Worn or missing heat shrink tubing on these games can cause all sorts of strange game behavior.

New pawl heat shrink tubing should always be installed when rebuilding the flippers. Cut the old tubing off using a razor blade. Cut a 1/2" length of new 1/4" heat shrink tubing. Push it over the pawl, and use a heat gun or hair drier to shrink the tubing in place. Trim with a razor blade as needed.

Installing the flipper pawl and flipper
coil. Note the use of the white plastic
flipper "tool" to get the spacing correct.

Flipper Coil Types.
Often, operators will replace a flipper coil with the wrong type. This happens quite often. You should verify in the manual that your particular game has the correct flipper coil installed.

Re-installing the Flipper Pawl Assembly and Flipper Coil.
After the flipper pawl assembly is rebuilt (or replaced), reinstall it. Put the plunger through the coil bracket. Make sure the pawl is down (toward the playfield). Push the flipper shaft through the flipper bushing and into the pawl assembly. Do not tighten yet.

Put a new coil sleeve in the flipper coil. If you can't get the old coil sleeve out of the coil, replace the entire coil (it has been heat damaged otherwise the coil sleeve would easily slide out). The coil sleeve should be installed from the non-terminal end of the coil, and extend through the coil at the terminal end about 1/8".

Put the flipper coil in place, the coil end with the wire terminals goes closest to the flipper pawl. Note the nylon "tab" that is molded into the nylon terminal portion of the coil. This tab will fit into a notch in the coil bracket. The extended part of the coil sleeve will go through this coil bracket too. Install the coil stop and its two allen bolts.
Changing to the New Style Flipper Return Spring.
Williams changed flipper return spring styles in 1992. So on system 11 games, there's a cone-shaped flipper return spring that goes over the flipper plunger. The problem with this set up was it chewed up the flipper link, and often the spring just got weak and broke from the constant contact with the flipper link.

To combat this problem, Williams made two changes. First they changed the style of flipper link to be thicker, and have a more rounded contact point. Second they stopped using a cone style return spring. The return spring was moved outside of the plunger, where it takes less abuse and doesn't chew up the flipper link.

Left: Here the flipper plunger spring has gone soft, and won't return the flipper back. Note how the spring is biting into the flipper link (new style flipper links help prevent this).
Right: A conversion to the new style return spring. This involved using Fliptronic flipper pawl parts, and drilling a 1/16" hole in the metal bracket holding the flipper capacitor. Be careful you don't damage the EOS capacitor when doing this modification.


To change to the new style return spring on older flippers, just order the fliptronics style flipper pawl (the only difference is an added spring lever). Then drill a 1/16" hole in the bracket that holds the flipper capacitor. This hole will anchor the new style return spring. Be careful when drilling the new hole you don't damage the EOS capacitor. Entire flipper pawl, with plunger and link is part number #A-15848-L (left), or -R (for right). The flipper pawl only is part number #A-17050-L (left), or -R ( for right).

Tightening the Flipper Pawl Assembly.
Now you are ready to tighten the flipper pawl assembly to the flipper shaft. Williams provides a white plastic spacing "tool" (that comes with every game) which fits between the flipper bushing and the flipper pawl (see above picture). This spacer is .030" thick (1/32"), or about the thickness of three business cards.

Using a toothpick as a flipper alignment tool.

On the top of the playfield, note the roll pin inserted through the playfield, just behind the flippers. This pin is used for alignment purposes at the factory when the playfield was first assembled. Put a toothpick into the roll pin, and move the flipper against it (with the rubber installed on the flipper). With the flipper positioned correctly, lift the playfield and tighten down (very tight!) the flipper pawl assembly's allen bolt. Remove the flipper spacing tool and the toothpick. I wouldn't suggest trying to push the roll pins back through the playfield for flipper alignment; just use toothpicks. No need to possibly damage your playfield!

Both flippers in the "up" position. Notice how they look symmetrical.

When you are finished, extend both flippers to the up position. They should look "equal", both extending the same amount. If not, you will need to re-align one or both of the flippers. If you didn't replace the flipper coil stops (and instead filed them down to remove a mushroomed head), the flippers may not line up when extended. This happens because the plunger travel has increased from filing the coil stop.

Cleaning and Adjusting the EOS Switch.
Cleaning and adjusting the EOS (end of stroke) switch is the last step in rebuilding flippers. This is VERY important. The EOS switch is what diverts power away from the high-powered side of the flipper coil. If not adjusted correctly and the EOS switch stays closed, the flipper coil can burn. If the EOS switch is dirty and doesn't make good contact, the flipper will be extremely weak. Therefore it's critical that the EOS switch be adjusted and cleaned on all system11 flippers.

Clean the EOS switch contacts with a small metal file. There should be no pitting in the contacts when done. The EOS switch is a normally closed switch. So adjust the non-fliptronics EOS switch so it opens about 1/8" at the end of the flipper's stroke. If the switch is in really bad condition, replace it.

Parts Reference.


• Flipper Rebuild Kits (for two flippers). Includes all the following parts, plus some others. Part number A-13524-8 (actually for WPC fliptronic flippers, with the new style return sprint). The old style cone spring style (not recommended) is part number #A-13524-1.
• Entire Flipper Pawl, with Plunger/Link: #A-15848-L (left), or -R (right).
• Flipper Pawl only: #A-17050-L (left), or -R (right).
• Plunger/Link: #A-10656 (or A-15847 which has a slightly meatier link). Use this plunger/link for the older spring set up where the cone-shaped flipper return spring is over the plunger.
• Nylon Flipper Link only: #03-8050 (or 03-8753 which is the meatier link).
• EOS Switch: system 11 high voltage type #03-7811.
• Coil Stop: #A-12390 (uses two allen head 10-32 x 3/8" bolts)
• Coil Sleeve: #03-7066-5, 2 3/16" long.
• Flipper Link Spacing Bushing: #02-4676
• Flipper Bushing: #03-7568 (uses three 6-32 x 3/8" bolts and nuts)
All of these parts are available from your local Williams distributor, the Pinball Resource (914-473-7114), or Competitive Products Corp (800-562-7283).

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End of System 11 Repair document Part Three.


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* Go to System 11 Repair document Part One
* Go to System 11 Repair document Part Two
* Go to the Pin Fix-It Index at http://marvin3m.com/fix.htm
* Go to Marvin's Marvelous Mechanical Museum at http://marvin3m.com