1986 to 1990, Part One
by email@example.com@provide.net, 09/18/01.
Copyright 1999-2001 all rights reserved.
IMPORTANT: Before you Start!
If you aren't up to repairing your circuit boards yourself, I highly recommend Tom Callahan or John Robertson (in Canada). Note these repair facilities will NOT repair your circuit board after it has been unsuccessfully repaired by you.
Table of Contents
1a. Getting Started: Experience, Schematics
Little experience in fixing pinballs is assumed. Basic electrical knowledge is helpful, but not necessary. I do assume you can solder and use the basic features of a Digital Multi-Meter (DMM) such as measuring voltage and resistance. Please see http://marvin3m.com/begin for details on the basic electronics skills and tools you will need. This document should help if you just bought your first (or second, or third) pinball "as-is", and hope to fix it.
Online schematics are available too at http://www.stormaster.com/RGP-Stuff/manuals/williams-system-11a.zip (900k) in ZIP format (WinZip required). These are system 11A schematics, from the game F-14 Tomcat. Individual scans are in TIF format.
1b. Getting Started: Necessary Tools
Non-Specialized Tools Required:
Specialized Tools Required:
Cleaning "Tools" Required:
1c. Getting Started: Parts to Have On-Hand
Parts to have:
You can order the transistors and diodes from many sources. I would suggest Hosfelt in Ohio at 800-524-6464. They have cheap prices, no minimum, and good service. Also you can get the 6802, 6808, 6821 and 6116 chips from Jameco at Jameco.com and BGMicro.com. Lots of pinball parts can be ordered cheaply from Competitive Products Corp (800-562-7283) too. They have great prices on fuses, plunger & links, coil stops, EOS switches, flipper link spacer bushings, barrel springs, pinballs, optos, bridge rectifiers, etc. All other parts (especially game specific parts) and schematics should be ordered from Steve Young's Pinball Resource (845-473-7114 or mailto:PBResource@idsi.net?subject=from_the_Sys11_Repair_Document), or in Europe from Pinball Heaven at mailto:Phil@pinballheaven.co.uk?subject=from_the_Sys11_repair_document.
1d. Getting Started: Different System Generations
Changing CPU boards amoung Early System 11 games.
System 11 CPU board.
System 11A CPU board.
System 11B CPU board.
System 11C CPU board.
Score Displays Used in System 11 Games.
Williams Schematics for System 11 Games.
1e. Getting Started: Game List
Here are the list of games and their system generations. This is important to know before you begin repair.
1f. Getting Started: The Circuit Boards and How they Work
A prefix number preceeds all connector "J" numbers. This prefix signifies which board the connector belongs to. The number immediately after the "J" is the connector number for that board. The number after a hyphen is the pin number for that connector. For example, connector 1J8-5 would be CPU board connector 8, pin 5. Here are a list of board number prefixes:
Switched Solenoids (Multiplexing).
Multiplexing works like this; when the bank select relay is de-energized, solenoid power is connected to bank "A". Then only solenoids 1A to 8A can be driven by the driver transistors. There is no power available to bank "C". The "A" bank is usually reserved for coils.
When the bank select relay is energized, solenoid power V+ is connected to bank "C". Then only solenoids 1C to 8C can be driven by the driver transistors. There is no power available to bank "A". The "C" bank is usually reserved for flash lamps.
Norbert Snicer's description of System 11 multiplexing. Note the
solenoid power V+ on the left is directed to either bank A (top) or bank
C (bottom) by the bank select relay, through transistor Q8 (or Q7 on
earlier system 11 and 11A games).
There are also eight "controlled solenoids" on system 11 games, in addition to the above "switched" solenoids. These are solenoids 9 to 16. These can control only one device (unlike the switched solenoids which are multiplexed). Note if your game doesn't use the above solenoid bank switching (like High Speed and Grand Lizard only), all solenoids are considered "controlled" solenoids.
Williams' ROM software originally did not have CPU control of "special solenoids". These six solenoids includes the pop bumpers, kicking rubbers (slingshots), and kickback solenoids, and sometimes other coils. The original theory behind this was these items needed instant response. Having them controlled by the CPU would add enough of a delay to slow the solenoids down. After all, the CPU had to sense a switch closure of a pop bumper, then turn on a transistor which would fire the pop bumper coil. All this while the CPU was doing all the other chores it does (like scoring and controlling other devices). It was thought that this would not happen fast enough for good game play.
special solenoid pop bumper. Note the two switches;
one to activate the pop bumper, and one connected to
the switch matrix which controls the scoring and sound.
Eventually Williams changed their mind on these "special solenoids", and made them CPU controlled. This means regardless of how long a solenoid's switch was closed, the solenoid would be energized only once by the CPU, and for a pre-determined time. So if a switch got stuck closed, the coil would not lock on or "machine gun" and burn (or blow a fuse). Williams started this with their last system 11a game "Big Guns".
Special Solenoid Logic Flow.
SSx: 6821 PIA 7407 7402 2N4401 TIP122 --------------------------------------------------- SSa: U38 (pin 39) to U49 to U45 to Q74 to Q75 SSb: U41 (pin 39) to U49 to U45 to Q70 to Q71 SSc: U41 (pin 19) to U49 to U45 to Q72 to Q73 SSd: U38 (pin 19) to U49 to U45 to Q68 to Q69 SSe: U54 (pin 19) to U49 to U50 to Q76 to Q77 SSf: U54 (pin 39) to U49 to U50 to Q78 to Q79
Since pre-Big Guns games use hardware logic to fire the solenoids, there are some other smaller (and easily damaged!) components that can fail too. Check capacitors C70 to C75 (.01 mfd), and resistor network SR20 (4.7k). If these become damaged, a special solenoid can "stick on". Even if your game is Big Guns or later (CPU controlled special solenoids), damage these components can cause problems.Williams' diagram of the special solenoids "On" state logic.
CPU Board Connector 1J18 (Special Solenoid Switches)
50 volt Coils in Early System 11 Games.
to control 50 volt coils.
Robert Snicer's drawing of how early system 11 games handled the
higher voltage 50 volt coils, using a under the playfield relay
The power supply board provides +5 volts for all circuit boards. It also produces the +100 and -100 volts for the score displays. It also acts as a liaison for the +18 volts for the lamp matrix (no circuit, just a fuse) and the general illumination (GI) on games before Banzai Run. The power supply board does some mild processing of the solenoid voltage too.
This particual power supply version was used from Big Guns to Cyclone,
because it lacks the relay in the lower right corner for the A/C
bank select, but still has the GI connectors (that were moved to
the Interconnect board on Banzai Run and later games).
Starting with Taxi, a new power supply was used, number D-12246.
Low +5 volts from the Power Supply board.
Starting with Big Guns, system 11 games had an additional "auxiliary power driver" (APD) board. This board was used to hold the:
Zero Ohm "Resistors" on the Auxiliary power driver
Starting with Banzai Run, Williams started using an "interconnect board" inside the backbox (note the Banzai Run interconnect board is unique to other interconnect boards). Often this long, skinny board was mounted beneath the CPU board, or on the sides of the backbox. This board was a "truck stop" for lamps (GI, controlled, flashers), switch matrix, and coil power on the game. The lamp GI (general illumination) wiring from the playfield would come here, go through some fuses, and then continue on to the CPU board. This board also held the resistors for the flash lamps. At this time Williams dropped resistor R1 from the flash lamp circuit and only used R2 on the interconnect board. This greatly increased reliability because flash lamp resistor R1 (330 ohms 7 watts) failed quite often. The interconnect board also holds several MOC3010 opto-couplers for the flipper lane change circuit (games before the interconnect board did lane changes with a second switch on the flipper cabinet switch).
Flipper Power Supply board.
on games Fire! and before.
Flipper worked different on games High Speed to Millionaire. These games used a series wound FL23/600-30/2600 flipper coil. The common lug (where both the low and high powered coil wires were connected together) on these flipper coils was the middle of the three lugs. Also these coils used ONE diode across the two outside lugs. The EOS switch on these games, when opened, enabled BOTH the high power and low powered coils together. This style of flipper coil did NOT use a 2.2 mfd anti-spark EOS capacitor. The problem with this series wound coil was the "back spike" of current that occured when the EOS switch was opened. This cause the EOS switch to excessively wear and pit.
The flippers are only enabled during game play and in diagnostic mode. The flipper enable relay is what turns the ground connected to the flippers off and on. This 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).
Norbert Snicer's drawing of the flipper circuit used from F-14 and
later. Notice the CPU board relay K1 that energizes the flippers during
2a. Before Turning the Game On: Check the Fuses
Most of the fuses for these games are located in the backbox.
block, for testing. These fuses are the four
general illumination fuses as used on pre-
Banzai Run games without an Interconnect
Don't depend on your eyes or sense of smell to check fuses. A perfectly good looking fuse could be blown, it happens all the time. Use your Digital Multi-Meter (DMM). First remove the fuse from its holder, (or remove just one end of the fuse from the holder). Don't try and test the fuse installed as it can give false readings, depending on the circuit. Set your DMM to "continuity", put a lead on each end of the fuse, and buzz out those fuses. No buzz means fuse is bad.
(Side Note: a "buzz" on your meter means zero resistance. If you don't get a "buzz", either the circuit is OPEN, or the resistance is 100 ohms or greater. If your meter doesn't have a continuity function, just use the lowest resistance setting. A good fuse will measure zero ohms.)
bridge, and the +18 volt lamp matrix bridge.
These two bridges are mounted inside the
backbox on the right side, just above the
large 30,000 mfd capacitor. Be sure to
label the fuse holders with the correct
amperage fuse (8 amp slo blo) and fuse type.
Always remove a fuse from its holder to test it. Do this because a particularly fatigued fuse will often fall apart as you take it out of its holder. You may never see this if the fuse is tested in its holder. This is especially true if the fuse tests 'good' then the fuse wire pulls away from an end-cap as it heats up.
A blown fuse: where did it blow?
Adding Fuses to System 11 games Fire! and
Though the following list will not apply to all system 11 games, here are the fuse types and locations of a typical system 11 game. All fuses are the slow-blow variety. Also there are probably other fuses in the backbox not located on circuit boards (for example on pre-Banzai Run games the general illumination fuses are located on fuse blocks inside the backbox).
Power Supply board.
Auxiliary Power Driver Board (Big Guns and later).
Interconnect Board (Swords of Fury and later).
Flipper Power Supply Board (Fire! and before).
2b. Before Turning the Game On: Burnt GI Connectors
The GI connectors can get hot and fail. This happens because the Molex connectors don't always have enough surface area to handle the GI power requirements. The heat from the connector will cause the solder joints to fatigue which causes resistance (and more heat). The connector pins get so hot they soften the solder. All this causes more resistance, which causes more heat. It doesn't end till the board burns, the fuse heat fatigues and fails, or the connectors pins fall out (or burn!), and open the circuit.
board. If any connector burns on a pre-Banzai Run system 11 game, it will
probably be this one. Note the yellow wires to the left of this
connector are the GI wires coming into the power supply board
from the transformer. The connector for these yellow wires are
on a "pigtail". This connector rarely burns. Also note since this
is a Big Guns to Cyclone power supply board, there is no "solenoid
A/C select relay" just above connector 3J8 (it was moved to the
Auxiliary power driver board).
The GI connectors on the Interconnect board, for games
The Interconnect board and the GI.
Fixing a Burnt Connector.
When replacing the Male Header pins...
A crimping tool (top), two different types of pins (left),
Crimp-On Pin Connectors vs. Insulation Displacement Connectors
Trifurcon Connector Pins.
Note Molex sells these pins in "strips" or on a "reel". Do NOT buy connector pins this way! Always buy them in "bags" (separated). It's just too difficult to cut them when they are in strips. If you don't do a good job cutting them, they won't insert into their plastic housing correctly. Also always get the tin plated version, NOT the gold plated pins.
Board Mounted Header Pins.
2c. Before Turning the Game On: Quick and Dirty Transistor Testing
I replace the bad TIP122 transistor(s) with a more robust TIP102 immediately before I turn the game on. I also usually replace the associated pre-driver 2N4401 transistor too.
2d. Before Turning the Game On: Should I leave my Game Powered On?
Although commercial pinball machines can handle being powered on continually, I would recommend you do not leave your games turned on when not in use. Here are some reasons:
Leaving your pin on all the time can cost much more than any potential damage you could do turning it off and on as you need it.
3a. When things don't work: Replacing Components
Please see http://marvin3m.com/begin for details on the basic electronics skills and tools you will need when replacing circuit board components.
When replacing components, the object is to subject the board to the least amount of heat as possible. Too much heat can lift or crack the board's traces. Too little heat and you can rip out the plated-through holes when removing the part. New circuit boards are too expensive to replace. So you must be careful when doing this.
To remove a bad component, just CUT it off of the board, leaving as much of its original lead(s) as possible. Then using needle nose pliers, grab the lead in the board while heating it with your soldering iron, and pull it out. You can clean up the solder left behind with a desoldering tool.
When replacing chips, alway install a socket. Buy good quality sockets. Avoid "Scanbe" sockets at all costs! A good machine pin socket is desirable.
3b. When thing don't work: Checking Transistors/Coils (locked on coils)
The Bank Selected Solenoids.
To make things even more confusing, some System 11 games do not utilize the solenoid A/C select relay. For example, the first two system 11 games (High Speed and Grand Lizard) do not. There are enough transistors on the CPU board so there is no need for any transistors to be shared between two devices. In this case transistor Q7 is used for a kickback lane (on High Speed) and the A/C select relay is present (but not used).
First Test the Solenoid A/C Select Relay!
I recommend the first thing you do is to test the solenoid A/C select relay. To do this, take your aligator test wire and connect it to the metal tab on transistor Q7 (Fire! or before) or Q8 (Big Guns or later). Then with the game on and in attract or diagnostic mode, touch the other end of the aligator clip to the ground strap in the backbox. You should hear the A/C select relay click on and off on the power supply or Auxiliary power driver board.
If you don't hear the relay "click", you should now test transistor Q7/Q8. The quick and easy way to do this is:
Is the Solenoid A/C Select Relay Bad?
Turning on Relay A/C to test both coils/flashers that
Transistor Testing procedures, circuit board out of the
To test a transistor, you'll need your digital multi-meter (DMM) set to the "diode" position.
Testing a TIP36c on the Auxiliary power driver board.
Testing a 2N4401 pre-driver on the CPU board.
Testing a TIP42 lamp matrix column driver transistor on the CPU
Most often transistors short when they go bad. This will usually give a reading of zero or near zero, instead of .4 or .6 volts.
in the "down" position (as shown here). If the center
button is "up", you will enter the audits menu instead.
If your game powers on, you can use the diagnostics to test most devices. From the attract mode:
If a solenoid doesn't work from the diagnostic tests, here's what to check. Turn the game off before doing this.
Testing for Power at the Coil.
Coil Test to Make sure Coil is Good.
Testing the under-the-playfield Relay Board.
The under the playfield relay boards were no longer required on 50 volt coils with games that had an Auxiliary power driver board (APDB). That's because the APDB had TIP36c transistors to control the 50 volt coils, replacing the need for the small relay boards. But some games even with the APDB still used under the playfield relay boards for other uses (like turning off specific strings of GI lights, like on Big Guns).
Coil or Cracked Solder Joints on the Relay Boards.
Grounding the "DRV" lead with an alligator clip on the
If the coil fires in the above test, you may have a transistor problem. You can also test the TIP122/102 transistors this way. Only do this for the TIP122 or TIP102 transistors! Damage can occur if this test is done on other transistors (like TIP42 or TIP36). This test will test everything from the CPU board down to the coil itself. If the TIP122/102 and coil pass this test, and your coil still doesn't work in game play, you have a problem more "up stream". All that is left is the 2N4401 pre-driver transistor, and the logic TTL chip that ultimately controls the whole process (a 7402 for the special solenoids or 7408 for the standard solenoids).
I've Done the Above Tests & they Work, but the Coil still
doesn't work in Game mode.
If the coil in question is a special solenoid (pop bumpers, slingshots), you need to look at the driving components. There are some other smaller (and easily damaged!) components that can fail too for the special solenoids. Check capacitors C70 to C75 (.01 mfd), and resistor network SR20 (4.7k). If these become damaged, a special solenoid can "stick on". Even if your game is Big Guns or later (CPU controlled special solenoids), damage to these components can cause special solenoid problems.
There are more components that needs to be tested or replaced too, if the transistors themselves are good. This is the hardware logic chips that drive the pair of TIP102/2N4401 transistors:
Turning on Relay A/C to test both coils/flashers that
Installing a New Transistor.
If you replace a coil's TIP122/102 transistor, it's a good idea to also replace its corresponding pre-driver. It will be located near the TIP transistor. See the schematics to determine the specific pre-driver transistor(s).
Game with an Auxiliary power driver board (Big Guns and later), use a bigger TIP36c driver transistor for high voltage devices. These TIP36c transistors have TWO pre-drivers: a TIP122/102 and a 2N4401 transistor. Again, if the TIP36c has failed, it's a good idea to replace both corresponding pre-driver transistors.
Replacing the pre-driver transistors is optional (if they test Ok). You can always test these pre-drivers instead of just replacing them. But if the driver transistor has failed, the pre-driver was probably over-stressed too. It is a good idea to replace the pre-driver transistor(s) too.
Replace TIP122 transistors with TIP102?
games Fire! and before. Note the thicker
red power wire on the left goes to the
banded side of the diode. The thinner
wire on the right lug goes to ground.
On all electronic pinball games, each and every CPU controlled coil must have a coil diode. This diode is VERY important. When a coil is energized, it produces a magnetic field. As the coil's magnetic field collapses (when the power shuts off to the coil), a surge of power as much as twice the energizing voltage spikes backwards through the coil. The coil diode prevents this surge from going back to the circuit board and damaging components, or causing the CPU to get confused (which often results in a game reboot).
If the coil diode is bad or missing, it can cause several problems. If the diode is shorted on, coil fuse(s) will blow. If the diode is open or missing, strange game play will result (because the CPU board is trying to absorb the return voltage from the coil's magnetic field collapsing). At worst a missing or open diode can cause the driver transistor or other components to fail.
Remember to always install a coil diode with the banded end of the diode to the power wire coil lug! The power lug is the the one with the thicker red or purple wire connected to it. This is usually the lug with TWO wires connected to it (because the power wires "daisy chain" from coil to coil). If you install a diode in reverse, it will instantly short and be ruined when power is applied.
Sometimes a diode lead breaks on the coil from vibration. When replacing a coil, the repair person can install the coil wires incorrectly (the power wire should always be attached to the coil's lug with the banded side of the diode). To prevent this, Williams moved the coil diodes off the coils and onto the Auxiliary power driver board starting with Big Guns. This isolates the coil diode from vibration and eliminates the possibility of installing the coil's wires in reverse. This was done on most coils except the flipper coils.
If you suspect a problem with a coil diode (game resets during multi-ball when lots of coils are firing), you can test the coils on the Auxiliary power driver board. Just set your DMM to "diode" setting, and put the black lead on the banded side of the diode, and the red lead on the non-banded side. You should get a reading of .4 to .6 volts. If you reverse the leads, you should get a null (no) reading.
Test a Diode on a Coil?
But if you want to test a coil diode, you can. If the coil diode is mounted on the coil, you will need to clip one end of the diode off the coil lug to test it (that's why just replacing the diode is a good idea if you suspect a problem). If you game has an Auxiliary power driver board (Big Guns or later), the coil diodes are mounted on the Auxiliary power driver board. These rarely go bad.
Use your DMM set to "diode" setting, and test the board mounted coil diode. With the black lead on the banded side of the diode and the red lead on the non-banded side, you should get between .4 and .6 volts. Reverse the leads (red lead to banded side of diode), and you should get a null reading. If you don't get this reading, cut one lead of the diode from the circuit board, and repeat the test. If you still don't get these results, replace the diode with a new 1N4004 diode.
Installing a New Coil.
For games Fire! and before (with no Auxiliary power driver board), the coil's ground wire (usually the smaller wire) MUST go to the lug of the coil with the non-banded side of the diode. The power wire connects to the lug with the banded side of the diode. If you have the wires reversed, this essentially causes a shorted diode, which destroys the diode.
Coil Doesn't Work Check List.
Before you start, is the coil stuck on? (Hint: is there heat, smoke and a bad smell?). If so, the coil's driving transistor has probably failed. Turn the game off and check the driving transistor, and replace if needed. See Transistors Testing Procedures for more info.
If the coil just doesn't work, here's a list of things to check:
End of System 11 Repair document Part One.
* Go to System 11 Repair document Part Two
* Go to System 11 Repair document Part Three
* Go to the Pin Fix-It Index at http://marvin3m.com/fix.htm
* Go to Marvin's Marvelous Mechanical Museum at http://marvin3m.com