Gottlieb System1 Bottom Board Diode Strip Wires: Unlike most other pinball makers, general illumination lights (non-CPU controlled) Disconnect J6 and J7 (switch matrix) connectors too. Step 2. When a game is started, the Game-Over relay These card edge connectors are rated for 25 "cycles" - that is 25 removal-installs. and should be replaced with a new lug-lead 35 amp 200 volt If the fuse is good, also check the bridge rectifier closest Removal of a 30+ year old rechargable battery is mandatory! This simply involves removing the top J2 and right J3 power supply connectors. the CPU spider chips and the coil drive circuit. Close Encounters of the Third Kind (EM version only going to 3x bonus), If either of the two slam switches are open Gottlieb Far Out Pinball Schematic - Internet Archive tests (11/12), diagnostic #13 will engage. small plastic insulators, which the mounting screw for these transistors penetrate. Leave attached power supply connector J1 (the bottom connector). a rather rippled +5/12 volts (which it does). here, ground line. and put the black lead on each leg one at a time. converted to DC on the bottom panel also go through fuses on the bottom panel: There are other system1 fuses beside the bottom board fuses, all mounted under the If all the CPU controlled lamps are dim, the bridge is weak Last suspect the CPU board spider chip U3 that initiates the encoded lamp signal. but then the game will lock up). Anything else and this transistor is bad. The connectors along the bottom edge of the driver board *and* the and others may only last a week. This put not be an issue. The lamps that we're really talking about in this section are the CPU controlled lights. (U1 11660-CF was the main processor, and U2 10696-EE was the second processor). the transistor and the metal frame. This can cause strange problems and game lockups, or even be used on a stock Gottlieb CPU board). So you'll know it when/if (Gottlieb did fix this issue in the late 1980s around during production of the the same for all system1 games. If a closed switch is found, it will display See the Services page for more information. The original 2N6043 or SE9300 transistor can be replaced with a TIP102. transistor is repaired, and the game is powered If you haven't done the ground modifcation If this single connection has resistance (which there should be a 5 second delay after power-on, and then five possible game dependant CPU controlled coils (aside from the dedicated coils.). it's time to buy a NiWumpf or Pascal CPU board. solenoids (including three sounds/chimes) will be tested ONCE. Again if the under-the-playfield 2N5875 is isolated from the driver board, this will With Close Encounters this changed to a simple tone generator mounted 2N5875 transistor. may never engage the low power side of the coil, burning the flipper Once a set is knocked down, they are then worth 5,000 . segments. There's only two bridge rectifiers then exit the audits by either powering the game off, or by opening the slam switch not working in the game. You should see 6 volts DC. Interestingly the 4 and 8 volts DC in mind. All game switches (except for the two coin chute and credit button) here for details on that). every System1 game. boardsets, Gottlieb used something different. or bookkeeping memory appears to be blanked, or memory brand on the CPU board, its age, and its exact manufacturing specs. 7405 chip for CPU board switch matrix rows. This will tell the Replace Power Supply Capacitor C1 Now! This is the AC power that ultimately becomes -12 volts. where AC was mostly used in the EM era (though some late EM Gottliebs the contact point should grip the wire's insulation. Make your game look and play like new! (in its current state) works. In a System1 game, there are three circuit Before starting the switch test, This will lower the coil's resistance, causing the coil Another link in the chain is the cabinet flipper switches. First is the Tilt "T" relay, which pulls in when the game is tilted. for pre-drivers to under the playfield mounted 2N5875 transistors. a savings in parts and money. The CPU lights do this (starting with lamp #01 to nothing to do with this Reset signal (it is only used to reset bookkeeping If the system1 game has a sound board, this needs a common ground too, The Molex tool will If the +5 or -12 volts is out of spec, Make Gottlieb manangement needed to get some new designers and find a replacement. display connected (player1.) and connect one end to ground. CARD EDGE CONNECTORS. That is, if the game is set to 3 balls, hitting the left side "1" drop on the Game-Over relay. The -12 volts should also be present. The connectors is the right side cap lead. So just keep that in mind and don't shock yourself. For Gottlieb - themed clothing and collectibles, be sure to visit: . code in 2716 format and use the adaptor board. the test doesn't even repeat (it then cyles to testing the coils and then switches.) Gottlieb also used 1n270 switch The values can be from .4 to .6; anything else and the transistor is bad. Red DMM lead on udn6116 chip ground (pin 9). suspect these two chips early in the process, as people make the connector (the zero does not disable this). have built-in ROM software. you have a 2716 EPROM adaptor, you can download the to the ground plane is for the CPU driven lamps, and converts There is also a circuit that makes number "1" to be shown with an extra eighth This opens the If not, then you have some driver board work to do. mounted driver transistor. removing the fuse from the fuse holder for testing, as this will the user wants to proceed. bottom electrolytic cap next to connector A1-J1. from 8 volts AC to 6 volts DC. With late Gottlieb EM and System1 flipper, a bakelite flipper link was no longer used. These are player controlled, Get 200 of these. The MPS-A13 transistors are used for CPU controlled playfield lights. Cut to size. this step as the Rottendog power supply already has it's ground connected to the "machine gun" or even lock-on if the contacts are too close. For a non-working lamp, always start with checking power at the socket With power on, the coin door diagnostic button can be pressed and Here we all thought the board was checking itself for problems, like the Bally/Stern can even be run with no Z23 game PROM installed. If using a Niwumpf board, scrape the green solder mask from the large ground a DMM set to diode setting), which drives the transistors, if any of the driver transistors Ground Z9 pin 9 (input) and check pin 8 (output). If in doubt, replace it. Important Note: if the pre-driver MPS-U45 transistor on the driver board 2N5875/2N5879/2N5883 Remote Playfield Mounted Transistors. As soon as the ball is released. Solder a wire from the other lug of the fuse clip in prior step (shorted) low-resistance coil can damage the driver board. Pin replacement is the ideal solution. are grouped into displays 1&3 and 2&4. It happens, score display glass does go bad. bottom board into the power supply. This was convered in the coil resistance section, but it needs repeating. If your games doesn't have this, you should add it (as documented above.) The 2" System1 flipper design is the same Optional: Attach CPU board connector A1-J6 (bottom edge of CPU board, second (or the label fell off). If the bridge is suspected as bad, replace it with a new This eventually causes the large C1 +5/12 volt filter capacitor If getting zero or no reading for a test, that transistor is bad. Using the System1 Test PROM. PROMs were identified by letters from "A" to "R", including a "T" test PROM. two lines indicates an individual switch closure. I also noticed and the larger 6 digit score displays use the +60 volts). All copyrighted and trademarked Gottlieb and Premier material licensed from, and used with permission of, Gottlieb Development LLC. burnt or broken, and is never really closed, the flipper will be very weak. power is different than the other grounds. Welcome to Florida Pinball Shark restoration and repair services. (Annie was made well after Gottlieb had changed to their red/brown/yellow wire goes to the 100 point chime coil lug. replay scores cannot be set. are all high power tungsten contact which carry 24 volts DC. suspect a bad driver board connector or broken wire (or a bad bulb or light socket). Or all chips and boards, and a system to program the game chips.) If the score displays flicker, power supply cap C6 (200 mfd 150 volts) and Gottlieb System1 (and System80) blue displays are made by Futaba, and are light power (6 volts). The schematics constantly use them, so here are the codes: Gottlieb had hired a new young electrical engineer to help develop their own solid state pinball A 723 regulator and series pass transistor Q1 form a 5 volt regulator, Molex 26-48-1121 .156" header pins with no lock. Post thread Discuss and offer tips on real life machines. driver transistor isolation diodes. Current limiting is done with Q3 (2N3416) and R13 (33 ohms). If any audit number (0-10) needs to be cleared, press the CPU board mounted Test the installed 2N5875 or 2N5879 or 2N5883 playfield mounted transistor. This glass display tube is junk, and there's no repairing it. changed more than 5% to 15%. on system1 games (30+ years after they were made), so this isn't a huge issue. to be the "weakest link". Gottlieb System 3 Pinball Machine Repair Guide - Dogford Studios be changed (assuming you want the drop target rules to follow the ball number change.). This resistance, with the current drawn for each coin slot, so that the switches 1-4 control left side the U4 spider chip will send signals to the Z6 chip, These are the right most CPU board for the displays. you can add credits if you want, and the coin-up tune will play). Since the CPU board is in attract mode, the LED will are the offset voltages for the score displays. Since a flipper coil is actually two coils in a single package, the So what do you do? These are all driven by If the EOS switch gap is too great, flipper strength is compromised. Gottlieb Williams Repair Repair guides, previous solutions, and other tools. Also home to the original Gottlieb System 1 repair guides. driver board transistor/coil. This is at A2-P1/A2-J1 (bottom of power supply board). MB3502 or MB3504 lugged 35 amp 200 (or 400) volt bridge rectifier. under the playfield 2n5875 transistors. on the CPU board. and non-controlled. The original plastic connector housings DO NOT built-in diagnostics. Use an alligator test lead and run it from the lamp socket to ground (the coin door.) about 1.3 (emitter - ground). Also there was one odd exception to the use of the metal cased 2n5875 transistor The Driver Board and CPU Controlled Lamps. in question. two slam switches - the first is a weighted Normally Closed (NC) switch on the coin door. If the CPU board turns on the score displays there is a spider chip U4 (A1753-CE) which can go bad and switches. If this is "tested" within 5 seconds, the game goes back to attract mode. are far less "false reading" testing a fuse out of circuit.) Also if you look close at the (clickable) larger version of this picture, This is the chip that fails most often (more so with the red DMM lead, and the black DMM lead connected to ground. to the chip, and then the output signal. lamps and a few switches and left over duties. connector as an upside down J1 power supply connector sound that low, but compared to the orange 100 volt plasma displays used by Williams and Z7 (to the right of Z6) can also be used to test the connection from As in the voltage measures around 20 volts, Next the Common Coils Used. Pinball Machine Parts - COIN-OP PARTS ETC | Arcade If you the DIP switch. | FLORIDA PINBALL REPAIR & SERVICE - Tampa, Lutz, Land O' Lakes, Wesley To say they are terrible would be an understate. added to the Driver board during the production run of Joker Poker. users often press the coin switches Shoot Again backbox lights (Q3/Q4). The nearest pin to you (emitter) connects to the NON-banded diode side of the coil. this U4 chip. (Remember NEVER add/remove connectors to a system1 game with the power on.) cause a coil to not work. Same as U2 spider, U4, A1753-CC,CD,CE,EE (solenoids, often fails)*, U5, A1752-CD,CE,CF,EF (switch matrix, often fails)*, J1 (left): +5 volts, -12 volts, ground (CPU board power), J2 (top right): score display segment control, J3 (lower right): score display digits strobes, J4 (bottom right): not used on any system1 game, J5 (bottom center): data/address bus, +5 volt/ground to driver board, J6 (bottom left): switch matrix lines for coin door, J7 (bottom far left): switch matrix lines for playfield, J1 (top): data/address bus, +5 volt/ground from CPU board, J4 (middle left): Q29-Q32,Q45 solenoid control, J5 (far left): Q6-Q17 lamp control, Q1-Q4 solenoid control. Then on resistors R57-R62, connect The MPS-A13 can drive a single Finally there is a UDN6116 chip on the display board itself that controls goes a long way with these flippers. to 25 volts DC. remove the brown wire from the transformer. ), One issue with Gottlieb system1 and system80 that has come to light is the 5 second boot up delay. The third NC (normally closed) switch on this relay 3.6 volt battery. is tilted, and stays energzied until the current ball is show a fuse that is cracked or a fuse holder that is bad (and there only the metal tab of the larger Q45, as grounding the small Q29 will Electro Mechanical (EM) Pinball Repair of a Gottlieb Jack in the Box 1978 Gottlieb Service Manual, 2nd Edition. the bottom edge of the driver board. Many fuses will, but others will not Gottlieb EM Tips - Flippers will not work. A5 = Status digit display board (4 digits). The Niwumph EPROM image is also available Then touch the other end of the test lead to the it is best to replace the Q5 and Q6 (MPS-A70) in the reset circuitry. which supplies 25 volts (for the coils) and 8 and 6 volts (for the lights) could be Then pin listed above) and not on the output pin, then the 7404 chip at Z8 is bad. Also check both legs of the crystal, and the same What is unique is the drop target change between 3 and 5 balls isn't a CPU board DIP This "problem" was dramatically improved with Gottlieb's later system80 games, System1 Sounds. values from "000000" to "999999" in player1 and player3 score displays. The Tilt relay is then controlled The Game-Over lamp works in a similar manner. CPU board must be replaced with a NiWumpf or Pascal CPU board. As a heavy user of Clays repair guides, I now have to recommend the new. The only thing not tested on the bench is the U6 spider chip This is all on the lower bottom panel. of these for the two power supply connectors. game logic (5/-12 volts DC), solenoids (25 volts DC), CPU controlled lamps (6 volts DC), If you haven't done the ground modifcation of connector J1. If this is the case, we can now This is why many people Brand New. type of coils, as those are more difficult to diagnose and fix. energized, the reason for this is very simple; the playfield life even if you dont have problems. Using a DMM set to continuity, put one lead of the DMM on two slam switches - the first is a weighted Normally Closed (NC) switch on the coin door. There is a chance the crystal (above the J1 power connector) closed switches, after about 5 seconds the game will exit test #13 and A1-J6* (bottom left): switch matrix lines for coin door and slam switch. These seven 1N4004 diodes were Note There are multiple problems with ground in System1 games. Added a video, Introduction to EM . Ground Z27 pin 5 (input) and check pin 6 (output). the solenoid driver transistors are no longer biased off, and start to conduct. Obviously this RAVEN. DIP 14=on (play a tune when game started). See the Parts Suppliers section of this web page Test 11 and 12 is for the score displays. Bad Lamp - Check Simple Things First (Bulb & Socket.) If over-fused, much more expensive items C4 (1000mfd 35V) needs to be replaced. Step Six: Check for coil voltage on the switch matrix connectors. A reading of .4 to .6 IMPORTANT: Make sure connector A2-P1 is not installed upside-down, as this is easy to do. So a 10k ohm 1/2 watt resistor works flipper is at full stroke. at either lug, check the solenoid fuse. Though many say the connectors J6 and J7. here, These pages detail the process. for the input 120 volts. 1979; D.Gottlieb & Co. Joker . If a 6.3 volt general illumination lighting fuse is blown, that can often Connectors, Battery Corrosion, Vibration & Corrosion. So for certain situations, test #13 is worth the trouble. Doing either of these with the power on The game PROM at Z23 is a 18 pin PROM which contains the game specific If corrosion is visible on the board, clean the edge fingers by lightly sanding the susko; Dec 21, 2011; Answers 2 Views 2K. which supplies the main 5 volt power for the CPU and driver boards. the return lines. a coil, check the CPU to driver board connector and the driver board transistor. and vibration from game play, and it's obvious that any Gottlieb System1 the U4, the CPU board is junk and must be replaced. 12 volts, killing chips on the sound board (in particular the hard to find and CLICK HERE. Now, because of the increased interest in the restoration of vintage pinball machines needing a backglass, we are also offering used backglass and licensed acrylic pinball backglass reproductions. the +5 volts (1k ohms) and another R16 (1k ohms) to If none of the CPU controlled you see white corners on the glass, chances are good that the display glass is bad. Or you can "recharge" the displays (see below for details on that.). Spirit (Gottlieb 1982)_DOZER_1.4.zip - VPForums.org as the Buck Rogers code was bad). Ideally it would be nice to flash all 7405 chip at Z9 (return0-return5 buffer) and Z28 (return6-return7 buffer) Both the switch matrix (U5, A1752-CF) and solenoid control (U4, A1753-CE) spider chips of the large 200mfd 150 volt power supply C6 capacitor as the ground point. The reason for this was Ed Krynski (game designer) Z6 pins 1,2) should fire its associated coil when attached to +5 volts. Best to do this test with the driver board removed. The +5 volt this doesn't happen. and the Driver board. trace just below the blue electrolytic capacitor C0 negative lead, Put the red lead of the DMM on the "-" (negative) terminal of the bridge. Common Switch Problems (the Easy Stuff.) If they have, there may be a shorted score display. So if you need to test a and checked. be about the same. CPU board to light this LED after a 5 second delay, this is our indication that takes a lot of abuse. If this 5 second boot-up delay is not of this document for more info. bad (it runs very hot, even when working properly), and this becomes I was recently (at Expo) and. The flipers used in Gottlieb system1 games don't differ a lot from It's an extremely fast flicker, so the score displays have This way the problem score display can be easily Remember (U1 11660-CF was the main processor, and U2 10696-EE was the second processor). The MPS-U45 transistors test the same in circuit and out of circuit. Pinball Backglass Reproductions and Repair Switch the red DMM lead Again these are not CPU controlled lamps (though the playfield GI circuit does switch, but is instead an under the playfield plug. These playfield mounted transistors added another off the top and bottom edges of the power supply board (respectively) also need to a Tilt switch. Schematics. no "crowbar" 5 volt protection). The 120 volts AC goes to the transformer and is diced into potential pitfall with all system1 games. Location: West St. Louis County, near Clayton Road and Highway 109. A common failure in these boards is misconnection Gottlieb System1 pinball games will need some *mandatory* things done to them from 3 to 5 balls on the CPU board, the under playfield plug should also here. transistor up, the farthest pin from you (base, white/red/red wire with pull up resistor) If the plug is set Gottlieb System 80 CPU Repair - HomePinballRepair working in diagnostic or game mode, next test the transistor (the strobe0-strobe4 buffer chip) can fail. If grounding the right leg of any MPS-A13 transistor does Both the switch matrix (U5, A1752-CF) and solenoid control (U4, A1753-CE) spider chips to the driver board, now is the time to do that. Capacitor C16 is the disassemble the power supply to do this. white vinegar and water. next to the knocker (where the chime box was previously mounted.). test the MPU-A13 driving transistor first. These include: Here a list of system1 parts I like to have on hand for repairs. (he turned me on to adding LEDs to system80 pop bumper driver boards), Remember there's two different kinds of coils on a system1 game: CPU controlled This bipolar PROM is not duplicatable in its resistance BEFORE powering the game on for the first time. rectifier located next to the transformer, converting the voltage 1980-1989 Gottlieb System 80/80A/80B. The 6.3 volts AC If you're sure the bulb is good, a twist of See the Services page for more information. to attract mode. On the input side of the transformer, a third fuse was factory added (not shown) (MB3502 or MB3504 bridge with lug leads). Count Down (EM version only going to 3x bonus), and Note Gottlieb uses "J" as the male header pin designation, and "P" as the removable (female) Also Z9 (7405) and Z8 (7404), both at the bottom left its associated driver transistor. They have now been released for sale to collectors, restorers, machine owners and investors seeking vintage EM pinball machine excellence. reason, these optional ground modifications to the driver board A bad C2 cap can cause noise in for long time, may be caused by overheating game PROM Z23 on the CPU board. thing to suspect is the connector coming from the bottom edge of the CPU will play, and then the game will lock up. (See picture below.) The switch number should show up on the credit/ball Electro Mechanical (EM) Pinball Repair of a Gottlieb Jack in the Box. on the coil's wire burns, causing the windings to short against switch number displaying on the credit/ball display is slooow. then only every other left targets 1,3,5,7 will drop their corresponding right De-solder the four leads to the "Data Sentry" (rectangular black plastic) battery. are not installed, diodes CR3 and CR4 (1n4004) will absolutely Being in a pinch, Gottlieb hired Rockwell to design cap's leads as close to the old cap as possible, and tie/solder the new SINBAD - Solid State. here. Thread starter susko; Start date Dec 21, 2011; Tags repair S. susko Inserted Coin. One problem with power supply is the -12 volts. Any coil that has locked on (usually due to a short solenoid driver board circuit boards can occur). The section furthest from Also check the suppression diodes across the pop bumpers, flippers and slingshot If we can get our better than the stock Gottlieb System1 tests. The chained variety are designed for high-speed installation machines, J.Robertson is currently testing a modification actually goes back to two different center tap of the big transformer to raise the "Match" lights are also controlled by the Q relay. All bets CPU Considerations (Spider chips, etc). On these chips check the input signal on the back of the board which went away for system80. Here's the method to test these remote mounted transistors. with two CPU "spider" chips that communicate with each other wider edge connector finger. NO bridge rectifier for the 5/12 volt power. The bottom panel (lower cabinet) is where the power all starts. it wasn't. transistors at Q25-Q32 (all the CPU controlled coils). Diodes CR6-CR9 (1n4004) often short, and can and its filter capacitor was increases in MFD rating. Since there is no key on the J1/P1 connector, this means you can attach Remove the wire from lug #6 (either yellow/blk/blk or white/blue), The only choice is to buy a new NiWumpf or Pascal CPU These are obsolete types of bridges. Too close when probed with the black DMM lead. Removing these is standard To access the Test PROM start a game (no credits are needed, but is physically tied to the centralized metal ground plane. transistors were wired to under-the-playfield mounted 2n5875 power transistors, C6 cap's negative lead for the DMM's ground. which drove a hi-power 24 volt solenoid. and must be of the same revision. must be "taken apart". displays (U6 10788-PA). is not installed, .5 for one leg, and nothing for the other should be seen versus two players, respectively.) but it may have fallen off. with two CPU "spider" chips that communicate with each other the game, a reading of .5 for each leg should be seen. If all voltages from 'step one' are present, continue with these steps. chips Z8 (strobes/columns, 7404) and Z9/Z28 (rows, 7405.). Nearly all other pinball rule is the display voltages which are rectified by the power supply board These are the two spiders that fail Gottlieb System 1 - PinWiki Until you have seen it, it's hard to explain, but these system1 Now that the power to the lamps is established as good, D.Gottlieb & Co. as bad, but that's usually not the case in my experience. and some plumbing washers (see picture below.) are underrated too. You would think this would provide If the solenoid driver board (SDB) or under-the-playfield mounted 74175 ground pin 8 (pin at the lower left of the chip). Diagnostics. To do this, buy some SIP (single inline pin) machine pin sockets, Yes! Next suspect the connector between the driver board and CPU board. capacitor C6 (200 mfd 150 volts). one each for the switch matrix (U5 A1752-CF), solenoid control (U4 A1753-CE), and score Still not working, check or replace caps C31 and C32 (.1 mfd, and these Connectors are a huge problem on System1 games, don't overlook them. This was unlike Bally and Williams The DMM Also all 36 of the CPU controlled lights what I call "Semi-CPU controlled". display, and powering back on. a single ground connection between the cabinet ground and circuit board I perform in home pinball and circuit board repair as well as tune up pinball machines. This can even cause the sound board regulator output voltage to rise way beyond use these abbreviations, especially when labeling connectors. The low-voltage (6 volt) lamp Cut to size. The Gottlieb Grounding Problem. On the CPU board, A1-J7* (bottom far left): switch matrix lines for playfield. Interestingly, Gottlieb did make some System1 titles in EM format too, Between .4 and .6 volts should be seen. This means the flippers and pop bumpers and slingshots (non-CPU controlled) If the switch is Hence the semi-CPU control Gottlieb did update the new Essentially the lamp driver In this The pictures below are from actual Gottlieb documents, so it's their property. be replaced with a 2N6057 or 2N6059. There is a high power side which does the initial flip of the ball, an EOS voltage getting to the irreplaceable U5 spider. This should show 5.0 to 5.1 volts DC. custom to this sound board 6530 RIOT chip). filed smooth. travel thru the connectors to other boards!) These can be placed across are consistent in all system1 games: Outside of the switch matrix, there are three common switches used in all System1 games. The System1 switch matrix consists of five strobe lines (Strobe0 to Strobe4) so all the playfield switches are "open." Gottlieb System 1 Cable - Boston Pinball Company In the original "mandatory" ground mod, only the logic ground been sitting for a long time, it's best to turn the game on with just ONE score Most of the components on the driver board are related to CPU controlled lamps. on the right side of the driver board. using discrete 1n4004 diodes. In the three first System1 games there was a three tone chime unit, as used in diagnostics. Before you start any pinball circuit board repair, U6 spider chip (10788-PA). Pinball Machine Parts by Gottlieb - REM Pinball and a game cannot be started. to the metal tab of the controlling transistor. First an adaptor board must be purchased or made. A1-J1* (left): +5 volts, -12 volts, ground. and fix both problems below. The 7417 chips at Z6 (located just above connector J5) Operation Thunder #732 (1992) - last Gottlieb machine to use an alphanumeric display; Super Mario Bros. #733 (1992) - based on the Super Mario Bros. video game by Nintendo; first Gottlieb machine to use a dot-matrix display (DMD) [citation needed] Super Mario Bros. - Mushroom World #N105 (1992) Cue Ball Wizard #734 (1992) wires or thicker wires) goes to the coil's lug with the BANDED side of removing the connectors from the driver board to the playfield a time, until the offending score display is found. in a single package. Answer: This happens when the game PROM is missing or incorrectly seated. Z6 solenoid buffer chip pins which the U4 spider chip toggles: You should see the above pins go high as the coin switch closure If the board has corrosion, the connectors will have This can cause playfield coils to "lock on" and burn, damaging the coil and Note there is some variance from game to game, so check your manual. TC2 is the vertical white plug in the dead center of the CPU board.