1986 to 1990, Part One Also this guide can be used for Williams System 9 games. by cfh@provide.net (Clay), 05/01/20. Copyright 1999-2020 all rights reserved.
Scope.
IMPORTANT: Before you Start! If you aren't up to repairing pinball circuit boards yourself or need pinball parts or just want to buy a restored game, I recommend seeing the suggested parts & repair sources web page. Table of Contents
2. Before Turning the Game On:
Many of the ideas in this repair guide are not original. Lots of people contributed to this document, and I just want to say, "thanks!" Below are a list of the resources used in the development of this guide. Some resources/people may have been innocently left out. If this is the case, and an idea is here that was originally yours, please notify me and I will make sure to give you credit!
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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://pinrepair.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.
Got Schematics? Online schematics are available too:
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: Order the transistors and diodes from many sources. I would suggest All parts and schematics should be ordered from someone on the suggested parts & repair sources web page.
1d. Getting Started: Different System Generations
Short method to ID different system11 MPU boards: Better explaination of all the different System11 MPU boards:
The least flexible CPU boards is system11c, since the sound circuit is completely removed, and a separate sound board is used. This board can only really be used in system11C games because of this. Populating the missing sound section on a system11C board would be difficult, as some of the sound chips are hard to find (and expensive). But the system11c CPU board can be used in many sys11/11a/11b games if the accompanying D-11581 sound is used too, though I haven't quite figured out how to do that (there are two sound ROMs on the System11b CPU board, and only one empty ROM socket on the D-11581 sound board, so some creative ROM combining may be needed). The most flexible CPU board is system11A. The system11A CPU board can be used in any 1986-1990 sys11, sys11b or sys11c game The only exception is if the sys11A CPU board is going into a original sys11 game (High Speed, Road Kings, or Grand Lizard). In this case, connector 1J15 (four pins, .156" molex male header) must be added to the sys11a CPU board (that's all that needs to be done). To use a system 11a board in a system 11c game, don't use connectors 1J16 (volume control) and 1J15 (speakers). Also the sound ROMs at U21/U22 and CPU at U24 and PIA at U9 are not used, since they are moved to the sound board. The original system11 CPU (as used in High Speed, Grand Lizard, Road Kings) is also very flexible, after the CPU board is modified slightly. It can work in any sys11, sys11a, sys11b or sys11c game with these modifications. CPU connector 1J18 pins 6,7 must be run to ground, otherwise the special solenoids will not work in sys11b and later games. Also there are six 1N5234 or 1N4735 6.2 volt zener diodes that should be added to the back of the CPU board for the special solenoid switch inputs. If using a system11 board in a system11c game, just don't use CPU connectors 1J16 (volume control) and 1J15 (speakers), and the sound ROMs U21/U22 and 6802/6808 U24 and PIA U9 are not used. System11B CPU board are also very flexible, and can be used in any System11A or 11C game. The System11b CPU board is not quite as flexible as System11a or System11, because sys11b is missing the U1 sound amplifier and associated parts. The System11b CPU will work "as is" in a system11a or system11c game. But a sys11b CPU won't work in a System11 game (High Speed, Road Kings, Grand Lizard) unless the sound amplifier parts are added back into the sys11b CPU board. If using a system11b board in a system11c game, the CPU sound ROMs at U21 and U22 and 6802/6808 at U24 and 6821 at U9 are not used.
For the first System11 games the external sound board was known as a "background sound" board, and the speech was handled by the CPU board's separate 6802/6821 at U24/U9 sound driven computer. Also the sound amplifier was on the CPU board. With System11a the external sound board D-11581 was a new board and more robust, with the sound amplifier used on this external sound board (though sys11a still had a CPU mounted amplifier, it was not used). The D-11581 sound board uses a 68B09E for the processor (and yes it must be a "B" and "E" version 68B09E chip to work, as the "B" gives a faster clock rate and the "E" gives an extended instruction set). With System11b, the D-11581 sound board had fewer parts (U6/U7/U18 not populated). With System11c all of the sound circuits on the CPU board was removed, and the external sound board did all the sound (and U6/U7/U18 were again populated). Note the sound board for system11a, b and c were the same board, but not necessarily with the same on-board components. The best version is the one with the most components (that is U6/U7/U18 popluated). The D-11581 sound board has some jumpers, since the board can use 27128, 27256 or 27512 EPROMs. If W2 and W3 are removed (below chip U4), the board is set to use 27256 EPROMs. If W2 is installed and W3 removed, the board is set to use 27512 EPROMs*. With this information it may be possible to combine the Sys11a/Sys11b CPU board 27256 sound EPROMs into a single 27512, and the external sound board 27256 EPROMs U4/U19 into a single 27512. Then use a fully populated D-11581 sound board jumpered for 27512 EPROMs with a system11c CPU board in a system11a or system11b game (making the system11c CPU board just as versatile as an earlier system11 CPU board). * Ok so maybe I lied about the sound board using 27512 EPROMs. It appears the system11c generation of the D-11581 sound board has two additional W10/W11 jumpers. For the board to be set to use 27512 EPROMs, W10 is installed and W11 is removed (in addition to W2 installed and W3 removed). The problem is on older D-11581 sound boards, there is no W10/W11 jumper. I believe this was the reason I could not get an older D-11581 to work with 27512 EPROMs. The schematics are of no help since this jumper is not shown. I believe the W10 jumper installed just ties all the EPROM's pin 1 together, and with W10 remove they are not tied together, and with W11 installed all the EPROM's pin 1 are tied to ground. But I may be wrong about that. Another twist to the D-11581 is the U1 D/A (Digital/Analog) converter. This chips talks with the Yamaha sound chip at U3, using the sound EPROMs as data, and plays the digital music the game designer wants. But this U1 chip has a personality. As some may have noted, the Williams D-11581 sound board is also used in some Williams video games like Arch Rival. So it would be logical to think you could take an Arch Rival's D-11581 sound board, load it with system11 pinball sound EPROMs, and have a replacement sound board. Well you would think, but it appears that is not the case. The U1 D/A converter is different for Arch Rivals. I know because I tried to use an Arch Rivals D-11581 (27256 EPROMs) with Earthshaker EPROMs, and got some very interesting sounds. The sounds were very much different and more rap/drum oriented. It just did not work. Putting the Earthshaker U1 D/A converter in the Arch Rivals board fixed the problem, and the board then played the correct Earthshaker sound track. If anyone has any solutions for the D-11581 27512 EPROM problem (correct jumpers) and the D/A converter problem, please contact me.
System 11 games used CPU jumper W7 (to the lower right of the battery holder) to specify the default language as English or German. If W7 is installed, English is the default. If W7 is removed, German is default. This was only used for early system11 games though. Later games (system11B/system11C) required both game ROMs U26 and U27 to be changed (language-specific versions), in addition to the jumper (but try the jumper first and if that doesn't work, then change the ROMs). Note the W7 jumper looks like there are two solder pads on the left side - really it's not that way, the W7 jumper goes to the outside left solder pad. Also if you install or remove the W7 jumper, you will need to remove the batteries to do a "hard reset" before the new W7 jumper takes effect.
Score Displays Used in System 11 Games. If you are doing CPU board testing, the 4 display glass master control panel (D-11610) used from F-14 to Swords of Fury can be used on the earlier games High Speed to Millionaire (which used 5 display glasses). The only thing not seen will be the ball/credit display functionality. On newer games Taxi and later that uses two 16-character alpha-numeric glasses, the older display panels can not be used (the panels are plug compatible, but the resulting text on the 4 independent display glasses is not readable).
Power Supply. When the Auxiliary Power Supply board was introduced with Big Guns, the D-8345 power supply was not fully populated. For Big Guns the lamp matrix and 25 volt coil connectors were removed, as were these associated fuses, but the GI connectors were still present. By Banzai Run, the GI relay/connnectors were gone, and the D-8345 power supply only had three fuses (one for high voltage, two for the 5/12 volt bridge rectifier). This under populated D-8345 power supply was used on Big Guns, Space Station, Cyclone, Banzai Run, Swords of Fury). The lower section with the GI connectors (on the lower right) was left blank (no GI relay or GI connectors). Also the 18 volt lamp matrix connector/fuse was removed, as was the 25 volt low-power solenoid connector/fuse. With Taxi Williams changed to a smaller power supply board #D-12246 that outputed -12, +12, +5, -100 and +100 volts DC and had just three .156" Molex connectors (no longer was the rectangle 12 pin input connector used). This was done so the new power supply could not be used in pre-Taxi games. All other voltages (18 volts lamp matrix, 25 volt low-power coils, 50 volt high power coils) was generated and fused by the Auxiliary power supply board, so there was no need for this to occupy space on the new smaller power supply board. Rottendog sells replacement system11 power supplies for around $70, but they only work on pre-Taxi games as of 11/05 (Taxi and later games have different connectors and are not plug compatible with the Rottendog power supply).
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.
* Sound board D11581 rev D has resistor R18-21 and chips U6,U18 installed (where the prior versions do not). 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:
Multiplexing works like this; when the bank select relay is de-energized, solenoid power (25 volts) 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 and bank "C" for flashers. When the bank select relay is energized, solenoid power V+ (25 volts) 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. Since flashers are 12 volts (not 25 volts), a large 5 watt (usually 5 ohm) power resistor was used to load the 25 volt circuit so it would not blow the 12 volt flasher bulbs. Also a large 10 watt 330 ohm resistor was used in the flasher circuit. When the flasher was not activated, it was "warmed up" by the 25 volts going through the flasher and a 330 ohm resistor to ground (sometimes the flasher filiment can be seen faintly glowing when not activated). When the flasher was activiated, 25 volt power would go through the 5 ohm resistor and the flasher to ground, via the "path of least resistance" theory, and activate the flasher bulb. Because the 330 ohm resistor was always sinking current, it got hot and often desoldered itself from the circuit (if the 330 ohm resistor was missing, the flasher would still work). Also the weight of these large resistors and vibration often broke the resistor leads, disabling the flasher (if the 5 ohm resistor was missing, the flasher would not work). This circuit was abandoned in the later WPC system (flashers were given their own 12 volt circuit, hence eliminating the need for these large resistors).
Two different solenoid voltages were used in all system11 games: +25 and +50 volts. The increase in solenoid voltage made the games snappier. Fifty volts was initially used just the flippers, and later 50 volts was used on pop bumpers and other random coils as needed like vertical up kickers. This was a sign of things to come, because the later WPC games went to 50 volts for all coils.) Unfortunately the CPU board was not designed to handle both 25 and 50 volts. On system11 and 11a games before Big Guns, a small relay board was often located under the playfield to drive the 50 volt coils. The CPU board's TIP122/102 transistor would activate the 25 volt relay on the relay board, completing the circuit for the 50 volt coil. The relay is really acting like a mechanical version of a TIP36 transistor (which was later used instead of the relay). On games Big Guns and before, there was a 50 volt fuse in the backbox for these coils too, and the 50 volts was fed from a small 50volt Power Supply board. Starting with Big Guns, the Auxiliary Power Driver board was incorporated, which used eight TIP36c transistors. This meant that Williams no longer needed the under the playfield relays to drive the 50 volt coils. The CPU board's TIP120/122 was now used as a pre-driver for the Auxilary Power Board's TIP36c transistors, which handled the 50 volts, and hence the relay boards were no longer used. Usually the pop bumpers and slingshots were 50 volts (five coils), leaving three more TIP36c transistors for other high powered coil functions. Also the Auxiliary Power Supply board has two bridge rectifiers (25 and 50 volts), and eight fuses just for the TIP36 controlled 50 volt coils.
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.
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.
CPU Board Connector 1J18 (Special Solenoid Switches)
Power Supply board.
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 board.
Starting with Banzai Run, Williams started using an "interconnect board" inside the backbox (note the Banzai Run interconnect board is unique compared 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 "landing zone" for lamps (GI, controlled lamp power, flashers), the 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 current limiting resistors for the flash lamps, and the bridge rectifiers for coil power and CPU lamp power. At this time Williams dropped the 'keep alive' power 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 - these opto-couplers prevented sloppy operators from shorting the 50 volt flipper coil EOS swithc voltage to the low-voltage lane change switches mounted next to them). Though Interconnect boards are largely the same from game to game (except for Banzai Run), the value of the flasher power resistors do vary. For example, if another Interconnect board is transplanted from a different game title, the flashers may be too weak or too bright. Why does this happen? Because the 12 volt flasher bulbs are actually run off the 28 volt coil voltage. To limit the current so the 12 volt flasher bulbs don't implode immediately, Williams used power resistors (now mounted on the Interconnect board, formerly mounted under the playfield). The values of these resistors varies directly to the number of flasher bulbs in any particular circuit. This is also why multiple flasher bulbs are wired in series instead of parallel (meaning if one bulb dies, none of the other bulbs in that circuit will light). The more flasher bulbs wired in series, the more resistance, and the less ohm value needed for the corresponding power resistor on the interconnect board. For example if only two flasher bulbs are wired in a circuit, then the interconnect power resistor will be around 7 ohms. But if four flasher bulbs are wired in a circuit, the interconnect power resistor will probably be more like 3 ohms.
50 Volt Power Supply board.
Flipper Differences. 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).
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2a. Before Turning the Game On: Check the Coil Resistance.
A very good idea for any unknown game just purchased is to check all the coils' resistance. If the game is new to you, and you have not powered it on, a quick check of coil resistance will tell you a lot about your new game. This takes about one minute and can save you hours of repair and diagnosing work. If the CPU board driver transistor(s) are repaired, and the game is powered on with a dead-shorted coil, this will blow the same driver transistor(s) again when the coil is fired by the game for the first time! It can also cause the game to immediately reset if the coil is forced into activation (because this is shorting the coil voltage to ground with no load). There is no sense making more work for yourself. So take 60 seconds and check all the coils' resistance BEFORE powering the game on for the first time. In order to check coil resistance, put your DMM on its lowest resistance setting. Then put the DMM's red and black leads on each coil's lugs. A resistance of 2.5 ohms or greater should be seen. Anything less than 2.5 ohms, and the coil and/or driving transistor may be bad. Now remove the wire from one of the lugs of the coil, and test the coil again. If the resistance is still the same (low), the coil or diode is bad (and also perhaps the driving transistor). If the resistance is higher than 2.5 ohms, the coil is good but the solenoid driver board transistor is shorted and will need to be replaced. Lastly, the coil's 1N4004 diode could be shorted too, giving a false low coil resistance. Cut one diode leg from a coil lug and retest the coil's ohms. Remember when reconnecting the wires to the coil that the power wire (usually two wires or thicker wires) goes to the coil's lug with the BANDED side of the diode attached. The thinner wire is the coil's return path to ground via the driver transistor and attaches to the coil lug with the non-banded side of the diode attached. If a low coil resistance is found, also suspect the associated driver transistor(s) as bad. A low resistance coil is a red flag, a warning, that there may be problems on the CPU board. Actually with System11 games, if a low resistance coil is found, I can pretty much guarantee that you will need to (should) replace of course the coil, but also all the silicon devices in its ground path (TIP driver transistor and probably the pre-driver transistor, and possibly the TTL chip that drives it). Always replace a TIP122 with the more robust TIP102.
2b. Before Turning the Game On: Check the Fuses
Don't depend on your eyes or sense of smell to check fuses. First remove the fuse from its holder, (or at minimum 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. A perfectly good looking fuse could be blown, it happens all the time. Use a Digital Multi-Meter (DMM) to test the fuse. 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 the DMM meter means zero resistance. If there is no "buzz", either the circuit is OPEN, or the resistance is 100 ohms or greater. If the meter doesn't have a continuity function, just use the lowest resistance setting. A good fuse will measure zero ohms.)
Another Reason to Pull a Fuse from its Holder to test it.
Another Reason to Pull a Fuse from its Holder to test it.
A blown fuse: where did it blow?
Williams made a design error on games before Fire. They forgot to add a fuse going from the transformer to the bridge rectifiers powering the +25 volts for the solenoids, and the +18 volts for the lamp matrix. If either of these bridges shorts, or capacitors that smooth the voltages fails, you game could start on fire (no joke). This has happened, so it is recommended that you add two new fuses.
Fuse Locations in System 11 games. Power Supply board. Auxiliary Power Driver Board (Big Guns and later). Interconnect Board (Swords of Fury and later). 50 volt Power Supply Board (Fire! and before).
Diagnosing a Blown Solenoid Fuse.
2c. Before Turning the Game On: Burnt GI Connectors & Non-Working GI
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.
The GI Relay(s). Often the GI relays develop cold solder joints (regardless if it is mounted on a separate small circuit board, or the main power supply board). Resoldering these relay or connector solder joints will often fix many GI problems. But sometime the GI relay itself may have failed. The contact switches on the relay burn, and no longer conduct. The only solution to this problem is replacing the relay (usually a 24 volt DC, 10 amp, DPDT relay). If either the playfield or backbox GI is not working, and there are no burnt connectors, the GI relay(s) are probably the problem. On games with multiple GI relays (like Cyclone, Elvira, etc), there's one relay for the backbox and one for the playfield. These two relays can be swapped; If the backbox and playfield GI relays are swapped and the problem moves, it is clearly a failed relay. If the problem does not move, it could be a CPU board driver transistor causing the problem. Remember is there's a driver transistor on the CPU board that turns the GI relay(s) on and off. If this driver transistor is dead or shorted, this can cause a GI problem (either the GI being permanently on or permanently off). For example, on Cyclone Q9 is the driver transistor for the playfield GI relay, and there's a different driver transistor for the backbox GI relay. See the driver transistor section of this document for testing and diagnosing these transistors.
The Interconnect board and the GI.
Fixing a Burnt Connector.
When replacing the Male Header pins... After the old GI header pins are removed, use a DMM set to continuity and "buzz out" each circuit board hole that has a trace connecting to it on *both* sides of the board. Put one lead of the DMM on the bottom trace, and the other DMM lead on the top trace. If a "buzz" is not heard, the plated through hole is cracked. To fix a cracked plated through hole, stitch a bare wire through the hole. Then solder it on both sides of the circuit board on the connecting traces (some green solder mask will need to be removed to do this). Make sure there is enough room in the hole to insert the replacement header pins! Another way to fix a cracked plated through hole is to solder the new header pins on BOTH sides of the board. The traces on top of the board will be a bit tricky; suspend the header pins up a bit to get the soldering iron between the board and the pins.
System 11b games and earlier used two square power supply plugs at 3J1 and 3J2 (newer system 11c games stopped using this style of connector). Sometimes these square plug power supply connectors get damaged (these connectors were used on Williams power supplies system 3 to system 11b, and on DataEast/Sega power supply until 1995). The six pin 3J2 is a ground connector, and usually does not get damaged. But the twelve pin 3J1 handles all the input voltages from the transformer to the power supply, so sometimes it gets burned. Finding the part numbers for these connectors was a real bear, as they were designed in 1971! So here are the part numbers for these wafer style, mixed pin connectors.
Crimp-On Pin Connectors vs. Insulation Displacement Connectors (IDC) Plugs.
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.
Connector Housings.
Polarized Pegs.
2d. Before Turning the Game On: Quick and Dirty Transistor Testing
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.
Testing the Power Supply. J5 connector (pre-Taxi) - high voltage for score displays: J6 connector (pre-Taxi) - logic +5 and 12 volts for CPU board: J2 connector (Taxi and later) - high voltage for score displays: J1 connector (Taxi and later) - logic +5 and 12 volts for CPU board:
Fixing Bad Power Supply Voltages. If the high voltage (+/- 100 volts) is missing or low or high, the score displays will not work. The HV section of the power supply will need to be rebuilt. The input 90 volts AC (3J1 pin 4 and pin 9 pre-Taxi) comes directly from the transformer, so there should be no issues with that (unless power supply HV fuse(s) are blown). If the +5 volts is high, suspect a bad 2n6057/2n6059 voltage regulator on the power supply. If the +5 volts (J6 pin 7,8,9 pre-taxi) is low, check J6 pin 6 (pre-taxi) for +12 to +15 volts DC. If this goes lower than 11 volts, there isn't enough "headroom" for the power supply to make +5 volts, and the game will not boot due to low +5 volts. You can also check the input AC voltage at 3J1 pin 10 and pin 11 (pre-taxi, should be about 12 volts AC). If the input 12 volts DC is low at J6 pin 6 (pre-taxi), put a DMM on low AC volts, and place the test leads on power supply capacitor C10. This should show less than .3 volts AC. If it is greater than this, replace cap C10 (15000 to 18000 mfd 20 volts). If J6 pin 6 (pre-taxi) is still below 12 volts, replace the BR1 bridge rectifier on the power supply. This should fix any low 12 volt DC input problems. If J6 pin 6 (pre-taxi) is +12 to 15 vdc, this means the BR1 bridge rectifier on the power suppy is good as is cap C10. Next this power goes to IC1 chip (723PC) and Q5 (2n6059/2n6059) to make regulated +5 volts. This should be 4.9 to 5.2 vdc (J6 pins 7,8,9 pre-taxi). If this voltage is low, first replace Q5 (2n6059/2n6059). Lamp matrix voltage on pre-Taxi power supplies include 3J4 pins 5,6,7,8 (+18 vdc) and 3J4 pins 9,10,11,12 (ground). On Taxi and later power supplies, the lamp matrix power does not go to the power supply board at all (it is wired directly to the CPU board at 1J4 pins 1,2,8,9 and grounded at 1J5 pins 1,2,6,7). If the lamp matrix voltage is missing, the lamp matrix won't work. Power for this is supplied by a bridge rectifier mounted to the metal backpanel of the interior backbox, and the huge blue capacitor and fuse next to it. On pre-BigGuns sys11 games, the solenoid voltage on the power supply include 3J3 pins 6,7,8,9 (+34 vdc) and 3J4 pins 1,2,3,4 (ground). This is the lower voltage solenoid power. Power for this is supplied by a bridge rectifier mounted to the metal backpanel of the interior backbox. The high voltage (50 to 70 volts DC) solenoid power is supplied by the smaller flipper power board beneath the power supply in the backbox. On sys11b games Big Guns and later, the Auxiliary Power Board has both the 35 and 70 volt solenoid voltages (there is no flipper power board and there is no backbox mounted low-power solenoid bridge rectifier). Also the power supply will *not* have a 3J4 connector for solenoid power. The Auxiliary power board on sys11b games Big Guns and later handles the solenoid voltages completely: J10 pins 1-4 is solenoid ground, J11 pins 8-10 is +35 volts DC, and J11 pin 2-5 is +70 volts DC. The A/C relay is also mounted on the Auxiliary Power board (formerely mounted under the playfield on earlier games), and turns on and off +35 and +70 volts on the Auxiliary power board at pins J11 1-5 (35 volts) and J12 pins 9-12 (70 volts). This is done in conjunction with the A/C driver transistors which control either a flash lamp or a coil.
2e. 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.
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3a. When things don't work: Replacing Components (Battery Corrosion, PIAs, etc.)
Please see http://pinrepair.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 chip, just CUT it off of the board, leaving as much of its original lead(s) as possible. Then using needle nose pliers, grab the chip 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. This is the safest method of chip removal and should cause the least amount of damage to the board. When replacing chips, alway install a socket. Buy good quality sockets. Avoid "Scanbe" sockets at all costs! A good dual sided socket is preferred.
Battery Corrosion.
An excellent approach to preventing battery corrosion is to mount a remote battery pack off the CPU board. This way if the batteries leak, you only ruin a $5 battery holder instead of a $250 CPU board. I highly suggest this approach. Another idea is to use a socketed coin style battery CR 2032. These work great on system11 games, last a very long time (up to 10 years), and don't leak. This is the approach I have been taking lately. The cost of the battery is about $1, and the socket is also about $1 (See BG Micro as an inexpensive place for these batteries and holders.) This is about the same cost as a remote battery pack and three AA batteries, and it's a cleaner installation.
Just north of the batteries are SIP (single inline) 8r 8c 10 pin resistor/capacitor networks. These can often be compromised by battery corrosion. Unfortunately these are difficult to find (4.7k ohm with a 470 PFD capacitor network.) They can be replaced with a straight SR resistor network (with no capacitors). If this is done, a "4.7k ohm x 9R" bussed resistor network can be used, but it must be installed correctly! This bussed resistor network will have ten pins, with one "common" pin (the pin with the "dot"). The common pin 1 of the resistor network must go in the board's pin 1 (for +5 volts). BUT the last pin 10 of the resistor network leg should be cut and not installed in the CPU board, because this pin on the CPU board goes to ground (for the capacitor part of the SRC, which we are not using since we're installing a SR and not a SRC).
If battery corrosion has happened to a system11 CPU board, often the traces around the battery pack are compromised. If this has happened, there are a number of components directly below (and *underneath*) the battery holder than are often affected. For this reason, and to aid in the replacement of PIA chips for other reasons, I will list where these large 40 pin PIA chips connect below. This way you can "buzz out" the chip legs and make sure they still connect to their intended components (because often battery corrosion can eat these traces). If even a single trace to one of the PIA or support chips is broken, this can cause the entire CPU board to not "boot", or for game functions to not work. (For example, a score display segment to not light.)
PIA and Support Chip Connections. PIA U41 (display) PIA U42 (display) PIA U38 (switch matrix)
U37 Support Chip.
(following not verified.) PIA U10 (sound/solenoids) PIA U51 (solenoids)
3b. When thing don't work: Locked-On & Non-Working Coils/Flashlamps (Checking Transistors/Coils)
Introduction. Essentially the driver board is a big computer controlled grounding plane. Through the game ROM program, the CPU, and the PIAs (Peripheral Interface Adaptors), the game can control which driver board transistor can "sink" a ground, and hence complete a particular coil's power path (causing the coil/flashlamp to energize for a short period of time). The way the driving logic works is as so: the CPU, which is running the game ROM program, wants to energize a coil. It tells the a PIA (Peripheral Interface Adaptor) to turn on the appropriate coil. This in turn drives a 7408/7402 chip, which then turns on a small "pre-driver" 2N4401 transistor. So far this is all done with "logic level" 5 volts. Then the pre-driver transistor turns on a much bigger TIP120/TIP102 transistor. This final link in the chain is what ultimately completes the coil's path to ground, causing the 28 volt coil to energize momentarily. A potential problem with this system is if ANY part in the chain shorts, everything else down the chain turns on, and a coil locks-on. Typically this is last link in the chain, the TIP120/TIP102/TIP36 driver transistor, becoming "shorted" internally (because this device is in direct line with the 28 or 50 volt solenoid voltage, where the other devices are "buffered" from this voltage). But it could be any of the other parts too! (the 2N4401 pre-driver transistor, the 7408/7402 chip, or the PIA chip!) It could even be ALL these devices short on! So instead of the CPU controlling the driver transistor (and hence its associated coil/flashlamp), the coil/flashlamp becomes lock-on (permanently energized), because the path to ground is shorted inside one or many of the controlling devices. So if a coil (or several coils) or flashlamps are locked-on, the TIP120/TIP102/TIP36 is at minimum is usually the cause. But the big problem is if the TIP120/TIP102/TIP36 driver transistor shorts, sometimes the "backlash" can ruin the parts behind it (2N4401, 7408/7402, PIA) that control the transistor.
Solenoid Power Circuit. On sys11b and later games with auxiliary power boards, the 28 volt bridge is now located there. In addition there is a 50 volt bridge for high power coils on this same board. The under-PF mounted 50 volt relay boards are discontinued on these games, as the Auxiliary power board has TIP36 transistors (pre-driven by the CPU board's TIP102/TIP122 transistor) to drive the 50 volt coils. The driver board and auxiliary power board driver transistors are the most probable source of solenoid problems.
What do the Driver Transistors Do? Sometimes these driver transistors short "on" internally. This completes a coil or flash lamp's power path to ground permanently, making it "stuck on", as soon as the game is turned on. Also a shorted pre-driver transistor, or shorted TTL chip (which controls the transistors) could be the problem (though a shorted driver transistor is the most common cause). To fix this, the defective component (and perhaps some other not defective, but over stressed componets) will need to be replaced.
Driver Transistor Operation. Each driver transistor has a "pre-driver" transistor. In the case of a TIP122/TIP102 (the most common driver transistor), this is a smaller 2N4401 transistor. Starting with System11b, under-playfield relay boards were no longer used for high-power (50 volt) kickers and other devices. In System11 and System11a, a TIP122 would turn on a small relay board mounted under the playfield. This in turn would momentarily turn on a 50 volt device (like a ball kicker). But with System11b and the Auxiliary Power board, this approach was abandoned. Instead of the under-playfield relay boards, TIP36 transistors mounted on the Aux Power board were used. These are pre-driven by the CPU board TIP122 transistors. If the main driver transistor is a TIP36c, this is pre-driven by both a TIP122/TIP102 and a smaller 2N4401 transistor. The bigger TIP36c transistor is an even more robust than the TIP122/TIP102, and controls very high powered 50 volt coils (like the up kickers, etc). Then before even the smaller 2N4401 pre-driver transistor, there is a TTL (Transistor to Transistor Logic) 7408 or 7402 chip. But the first link in the chain is the 6821 PIA chip. This is what in affect turns on the TTL and smaller 2N4401 pre-driver transistor, which then turns on the TIP122/TIP102 (which then turns on the TIP36c, if used for the coil/flash lamp in question), and energized the device. This series of smaller to bigger transistors is done to isolate the hi-powered coil voltage, from the low-power logic (5 volts) on the driver board. Also the 7408/7402 and PIA chips (all operating at +5 volts), which really controls the transistors, can not directly drive a high power TIP122/TIP102 or TIP36c transistor (which is controlling the coil's high voltage by sinking the ground). If ANY of these components in the chain have failed, a coil/flashlamp can be stuck on, and will energize as soon as the game is powered on!
I have a Stuck-on Coil (or Flashlamp), What should I Replace? Inside the front cover of the game manual is a list of each coil used in the game. Also listed are the driving transistor(s) for each coil. Use this chart to determine which transistors could potentially be bad. Also use the schematics. If after replacing the driver transistors the coil/flashlamp is still stuck on, then replace the TTL 7408 or 7402 logic chip. This TTL chip can also go bad. If there is still a problem, the 6821 PIA in front of the TTL chip can also die. Also remember to test the resistance of a coil BEFORE replacing the driver transistors. If a coil gets hot, it can burn the painted enamel insulation off the coil windings. This lowers the overall resistance of the coil because adjacent windings short together. If resistance gets much below 3 ohms, the coil becomes a "short", and will fry its associated driver transistors immediately!
A Coil just Does Not Work - What is Wrong? Another consideration are the CPU board connectors. On the special solenoids in particular, the male header pins on the CPU board that connect the switches to the CPU, and which connect the CPU back to the coil, can have cracked solder joints. Often resoldering these male connector pins on the CPU board can fix non-working coil problems.
Do the Transistor Test Procedures work 100%?
Types of Transistors Used on a System11 Driver Board.
Special Solenoids. At the time, it was felt that the clock speed of the CPU was not fast enough to give quick acting pop bumpers and slingshot kickers, as the CPU was doing other things like monitoring the switch matrix and running the lamp matrix and score displays. This opinion was all changed with Big Guns and system11b. Now Williams felt that the Special Solenoids should be CPU controlled. This was an excellent idea because now the Special Solenoids are "one shot" coils. That means if a pop bumper or slingshot switch gets stuck closed, the coil fires ONCE and only for a set duration of time. On System9 and System11/11a games, if a slingshot or pop bumper activation switch is stuck closed, the associated coil stays locked on! This burned up a lot of coils and driver transistors in these sys9 and sys11/11a games, which would blow the solenoid fuse and put the game out of operation. But the story doesn't end there with Special solenoids. The control of special solenoids on all system9 and sys11/sys11a games is directly through playfield control via the playfield trigger switches. But interestingly, special solenoid can also be controlled by the CPU too. This can be seen when running the internal game diagnostics, and the game turns the special solenoids on and off in the coil test. Because of these "dual trigger" (two ways to turn on) functionality of the special solenoids, these can be more problematic than the other 16 "CPU controlled" coils on the game. Special solenoids use a 7408 chip, a 7402 chip, and two transistors (2N4401 pre-driver and a TIP120/TIP102 driver). This is one more TTL circuit than the CPU controlled coils use. A special solenoid operates if the playfield switch pulls one 7408 input low. The other 7408 input can be pulled low by the CPU via a PIA (and this is what is done in the diagnostic solenoid test). So a special solenoid could work in diagnostic test but not work in game mode (or vice versa). This confuses a lot of people because the diagnostics show a coil a "working", yet when playing the game the same coil does not respond. Also the the special solenoid playfield switch trigger has a 100 ohm 1/2 watt resistor and a 22 mfd 100 volt electroylic capacitor (the positive lead connected to the resistor) in parallel to the switch. This is different than CPU controlled coils that use a switch matrix switch to turn them on (switch matrix switches only have a 1N4004 diode on the switch). Again the thing about special solenoids that is really freaky is this: the diagnostics can show the special solenoids as working, but in game play they may not work! The opposite is also true; a special solenoid could work in the game, but not in diagnostics. This happens because there are two different and distinct triggers for the special solenoids. That is, playfield trigger for the special solenoids uses different hardware logic then the diagnostic trigger for special solenoids. This can be very confusing. The logic flow for the special solenoids works like this: the PIA and the playfield trigger switch feed to the same 7408 chip. (Note the playfield trigger switch goes first thru a pullup 4.7k resistor which sometimes go open or out of spec causing problems.) The 7808 is an 'OR' TTL chip, meaning if either of the switch input are triggered (playfield or PIA), the TTL output turns-on the special solenoid circuit engerizing the coil. The OR'ed 7808 trigger signal then goes to a 7402 chip, which goes to a 2N4401 pre-driver transistor, and finally to a TIP120 or TIP102 driver transistor (which ultimately sinks the ground and fires the coil). So if a special solenoid only works in game mode and not diagnostics, the problem has to be the 7408 chip or the PIA chip. If the special solenoid only works in diagnostic mode and not game mode, the problem has to be the pullup 4.7k resistor, the 7408 chip, or the playfield switch (and associated cap/resistor on the switch) or connector for the playfield switch (common to have cracked solder joints on this connector). If a special solenoid works with one trigger but not the other, the 7402 and everything connecting after it (pre-driver, driver transistors, coil, etc.) are fine. To confuse things even more, the Special solenoids have yet another switch involved. This is the scoring switch, which is part of the switch matrix (unlike the special solenoid trigger switch). So each pop bumper and slingshot have a second physical switch mounted on the playfield device. This switch closes as the coil energizes. This switch matrix switch in turns tells the CPU to score the device (but does *not* tell the CPU to fire the coil). So if there's a pop bumper or slingshot that works fine (energizes), but does not score, often it's because this secondary switch matrix switch is mis-adjusted or broken.
The 50 volt Coils. On games before Big Guns (system11 and system11a), Williams used under-playfield mounted 50 volt relays for the 50 volt coils. The TIP122 CPU board transistor would momentarily energize the relay, which would in turn momentarily complete ground to the 50 volt coil. This required a relay board to be mounted under the playfield for each 50 volt coil. Williams stopped this with System11b (Big Guns and later). Instead they used the Auxiliary Power Board, which had large eight TIP36 transistors to drive the 50 volt coils. The CPU board's TIP122 transistors would pre-drive the Auxiliary Power Board's TIP36 transistors, which would sink 50 volts and energize the 50 volt playfield coils (this means the TIP36 transistors became essentially solidstate 50 volt relays). The Auxiliary Power Board (APB) also had eight fuses, one for each of the TIP36 transistors. Hence the 50v power supply board is no longer used on system11B and later games. The Auxiliary Power Board also had a bridge rectifier for the 25 and 50 volts circuit. The APB board is mounted directly below the power supply board on the right side of the backbox.
On all System 11 games, transistor Q7 or Q8 controls the "solenoid A/C select relay". This is the relay that controls which bank (either "A" or "C") that TIP122 transistors Q22-Q25 and Q30-Q33 will control. This means one TIP122 transistor can control two different devices (usually a flasher on bank C, and a solenoid on bank A). This was called "multiplexing". Note on System11 and System11A games before Big Guns (no Auxiliary power driver board), transistor Q7 controls the solenoid A/C select relay. On System11B and System11C games Big Guns and later (with an Auxiliary power driver board), then Q8 controls the A/C relay mounted on the Auxiliary power driver board. The solenoid A/C select relay is a 24 volt DC, 10 amp, DPDT relay (NTE R14-11D10-24P). The location of the A/C relay is somewhat confusing. On High Speed and Grand Lizard there is no A/C relay, as these two games do not use system11's multiplexing feature. On F-14 Tomcat the A/C relay is mounted under the playfield. Finding the A/C relay on system11A games can be challenging because under the playfield can be a lot of relays! This happens because prior to Big Guns all playfield 50 volt coils are activiated via a relay board. The 50 volt and A/C relay board are identical looking. Just remember on system11 and system11A the relay on the power supply is for the General Illumination, and the relay on the CPU board is for the flippers. The remaining playfield mounted relays are either a 50 volt coil relay or the A/C relay. Also remember some System 11 games do not utilize the solenoid A/C select relay. 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 50 volt kickback lane relay (on High Speed), and the A/C select relay not used.
If the solenoid A/C select relay is not working correctly, there will be strange game operation issues. A messed up A/C relay, if stuck on bank "C", won't give any power to coils 1 to 8. If the relay is constantly energized (stuck on bank "C"), it's probably because it's driver transistor (either Q7 or Q8) is shorted. If it's stuck on bank "A" (where the relay sits at rest) or won't energize, the flashlamps in the game won't work. If the A/C relay won't energize, the game will fire coils when its supposed to energize flash lamps! Or vice versa. This can give some very strange game behavior. If you are wondering what a particular relay does, any individual relay can be activated quite easily. All relays should have a 1N4004 diode associated with the relay. On playfield mounted relays, this diode is mounted right next to the relay on the relay board. On the power supply, CPU board, or Auxiliary Power Board the 1N4004 diode is right above the relay. With the game in diagnostic mode, connect an alligator test clip to ground. Touch the other end of the test clip to the NON-BANDED side of the relay's diode. This will energize the relay. If the game is in solenoid test and is testing one of the eight multiplexed solenoids, manually enerigizing the A/C relay should switch the test from the solenoid to a flasher (assuming the game is using a flasher for that multiplexed transistor). If it is a GI relay, when the relay is energized the GI lights it controls should turn off. If it is the flipper relay, energizing it should activate the flippers via the cabinet flipper buttons (note the flipper relay will automatically be energized when entering dianostic mode, so try this in attract mode). The solenoid A/C select relay can also be tested via its driving transistor. 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. This will make finding the relay a bit easier on system11 and system11A games. If you don't hear the A/C 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?
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 (they are not CPU controlled), 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.
Transistor Testing procedures, circuit board out of the game.
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.
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.
A Coil doesn't Work, What To Do.
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).
Cracked Solder Joints on the 50 Volt Coil Relay Boards. On the games using relay boards for the 50 volt coils, often the solder joints on the under the playfield relay boards are cracked or "cold". If you are having a problem with any device that is controlled by a relay board, re-solder all the header pin solder points on the relay board. Also the 150 ohm resistor used on the relay board can burn and go open.
Locked On 50 Volt Coil, Sys11/Sys11A. To fix this problem first make sure the coil's 1N4004 diode is not broken or shorted. Then look at the associated relay on the relay board. You will have to remove the plastic cover from the relay, which should pry off. Examine the switches on the relay, and adjust/clean as needed. To clean these relay switches, use a Flexstone file (this unlike cleaning the gold contact playfield switches, which should *never* be filed). Also make sure the 150 ohm resistor on the relay board is not burnt. When done, push the plastic cover back on the relay (it should snap in place). To test the relay and the 50 volt coil it powers, use the game's diagnostics. Or ground the non-banded side of the 1N4004 diode on the relay board (which complete 28 volts power to the relay board). This will energize the relay, which in turns energizes the 50 volt coil. Note there are two 1N4004 diodes on the relay board. The one you want to ground is the non-banded side of the 1N4004 diode that is by itself (*not* next to the 150 ohm resistor).
If the coil fires in the above test, you may have a transistor problem. You can also test the everything from the TIP122/102 downstream to the coil itself (but note this does not test the transistor itself). 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's TIP122/102 down to the coil itself. If this test passes, and your coil still doesn't work in game play, you have a problem more "up stream". All that is left is the TIP122/102, the 2N4401 pre-driver transistor, the logic TTL chip that ultimately controls the whole process (a 7402 for the special solenoids or 7408 for the standard solenoids), and possibly the driving PIA 6821 chip.
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:
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?
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.
Test the Coil Resistance with a DMM. To test the coil's resistance, it is best to remove the attached wire from one (either one) of the coil's lugs. Then set the DMM to low resistance, and put the DMM leads on the lugs of the coil. Most coils should be in the 5 to 15 ohm range, but could go as high as 150 ohms, or as low as 2.5 ohms. If the coil is below that, it should be replaced with a new coil of the same type. Coils with resistance below 2.5 ohms are basically a dead short, and this will fry its associated driver transistor.
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://pinrepair.com |