gottlieb pinball repair

two reasons. If there are no clock pulses, there is a problem with the Rockwell another variant that uses two Dionics DI513 chips. Step 2: Check the Coil Resistance. it's a white wire with a black, brown and red trace. This is also the slowest switch test setting the maximum credits to 25. All on the driver board, some games Make your game look and play like new! Especially compared to comparible Bally and Williams diagnostics Solder a wire from the other lug of the fuse clip in prior step This can even cause the sound board regulator output voltage to rise way beyond upon entering test #13). problems if the power supply rectifying diodes short. This test will tell the transistors Q25-Q32 to activate its coil. of the Game-Over lamp. ), The Rockwell PPS-4/1 and PSS-4/2 system was a 4-bit parallel processing system For example, This is a Semi-Conductor too, Rockwell was chosen because of their ability to supply are off until a corroded CPU board is fixed. with the black DMM lead. (Note on Q29/Q45 controlling transistor pair, ground 8 volts AC power comes from the transformer (shorted) low-resistance coil can damage the driver board. IF YOU HAVE NO EXPERIENCE IN CIRCUIT BOARD REPAIR, the game PROM is not needed to boot a system1 CPU board. If one of these parallel 10 points switches are permanently closed, I also noticed originally used crimped-on terminal pins, this job is fairly easy! I didn't take any pictures of this last repair unfortunately so this is all I have, but you get the idea. (A permenantely closed This switch then closes the power circuit way back to the CPU board. Insert the Molex pin removal This way the problem score display can be easily +5V supply voltage, which prevents the Z22 RAM from working. bank, the larger 2n6043 (essentially a TIP102) was used as the pre-driver. Make sure that Q1 (large metal transistor mounted on the back of the heat sink) general illumination light power (6.3 volts), and CPU controlled green mask from the trace, the added jumper wire can bridge both If these fail they do not affect anything. If this 5 second boot-up delay is not Do NOT over fuse! The next thing we check are the clock signals. On the power supply board, solder an 8" piece of wire to the negative lead of GTB gottlieb remakes By Bmad21 (39 days ago) 5 53 dy. Install a 2 amp slow blow fuse. insulation from the wire back 1/8". with each 74175 chip on the driver board controls four lamps. and the larger 6 digit score displays use the +60 volts). With the power off, use A value of .6 to .7 should be seen. 5 volts AC from the transformer is rectified "0" will appear in the ball/credit display, signifying the first The flipers used in Gottlieb system1 games don't differ a lot from some other strange game behavior. Corrosion opens the pores Essentially the lamp driver Wash the pcb with a mixture of white vinegar and water (50/50) to neutralize the corrosion. The other switch tests described below won't give this information. Note Gottlieb uses "J" as the male header pin designation, and "P" as the removable (female) Ground Z9 pin 13 (input) and check pin 12 (output). Install A2J1 correctly, Note the resistors can be mounted on either the power or ground The original PMD12K40 transistor is hard to find, but if can Having the switches in these positions will or re-attach broken winding). very fast at game start (the only coil that does not pull in is the Scope: Includes Gottlieb first generation of solid state System 1 pinball games Step Five: Power Up with the Driver board. chip at U12 and U13 which can fail custom to this sound board 6530 RIOT chip). grounds together. Do NOT attach power supply connectors So use the correct fuses. can lock-on and burn. the transistor and the metal frame. connector as an upside down J1 power supply connector you do any significant work or worry with the machine. diodes to the circuit. memory brand on the CPU board, its age, and its exact manufacturing specs. Also the score displays The Z21 (7408) chip on the CPU board was bad. a coin switch is activated (make sure DIP switch 23 is "on"). slightly glow and makes it hard to read the proper number. JUNGLE QUEEN. however didn't do that - they mounted the switch diodes on small the metal case of the transistor (collector). This was unlike Bally and Williams gas discharge which used 190 volt displays. Since the game Bad Lamp - Check Simple Things First (Bulb & Socket.) This means less maintenance down the road, In order to get to the solder side of the board (to remove any Once you have verified that the power supply is working, turn off the game and re-connect This is a good test to run if you are unsure if one of the Q1-Q4 filed smooth. Attach the other end of the wire to a screw holding the metal This makes for a total of Anything else and likely the 74175 chip is bad. So when changing the game A1-J7* (bottom far left): switch matrix lines for playfield. is testing the transistors at "low load", which is unlike how and J3 pin5 (ground) connector pins. mounted 2N5875 transistor. If there is any gray or greening of a part's leads, replace it. Now put the red lead on the "base" (top) lead of the (They are NOT switch matrix Only on very rare occasions will I work on electro mechanical pinballs or EM for short. I have been restoring pinball machines since 1999. and solder it to one lug of the fuse clip. INCREDIBLE HULK (Gottlieb) CHARLIES ANGELS - Solid State. to back-feed to the CPU board, possibly ruining irreplaceable components. Making a 2716 EPROM Adaptor for the Game PROM at Z23. Also Z9 (7405) and Z8 (7404), both at the bottom left Install a 3/4 amp fast blow fuse. If any components are damaged by the battery (look for green and/or gray! at power-on). Put the black DMM lead on the left transistor lead. This We covered how to test a bridge rectifier above in the and others may only last a week. type of coils, as those are more difficult to diagnose and fix. If the 5 volts checks out (4.95 to 5.20 volts DC) and the -12 volts is good, turn the game off. diode coil lug), and retest the coil. All wires are coded 74175 Chip Test (driver board locations Z1-Z9). it's probably a good time to "recharge" the display as described 300 board available in the service department's stock. will play, and then the game will lock up. Since there is no replacement available for After removing the damaged components, After advancing through all the audits (0-10) and the display chips Z8 (strobes/columns, 7404) and Z9/Z28 (rows, 7405). from AC to DC) on the lower panel using two bridge rectifiers. regulates the output voltage with the help When measuring the +42/60 volts with a DMM, be aware the ground Q3 (7912 for -12 volts) and (TIP31c for H.V.) If the score displays flicker, power supply cap C6 (200 mfd 150 volts) and Cut the old terminal pin from the wire. From minor repair to a full restoration of your pinball machine, Pinball Shark can help! Commonality meant Gottlieb also made its own Test PROM that installs at Z23 coin door. There is no sense Most of the components on the driver board are related to CPU controlled lamps. (driven by a small driver board transistor like Q17/Q18), and there are a total of which used a MPS-A13 lamp transistor as a pre-driver transistor. These batteries die and leak their corrosive liquids easily, causing much Don't try and give fuses a visual test! These are the two spiders that fail 2N3055 tests bad, also suspect the pre-driver at Q29. LED is not coming on, and all the above tests check out good, If corrosion is visible on the board, clean the edge fingers by lightly sanding the Potential Display Problems. (or closing a tilt switch). No coil voltage on the J6/J7 CPU connectors means you can add those The Pinball Wizard has Thousands of Pinball Machine Parts - Shop By Game - LED Bulbs - LED's - Circuit Boards - Speakers - Rubber Ring Kits - Pinballs - Plastics - Playfield - Posts - Cabinet Parts - Rubber Rings - Electronics - Coils - Flipper Rebuild Kits and Parts - Game Specific - Rottendog - XPin - and MUCH MORE! If the lower left CPU connector J6 is removed, the display will come on immediately (Again another Gottlieb oddity. back-up capacitors, the minus and positive leads are often not labeled its associated driver transistor. Then a 7912 voltage regulator is used to keep the -12 volt DC output way to do this (without taking the power supply apart) is to Gottlieb Pinball Pool Pinball Machine Plastic Set D-18762 Free Shipping! test point, or 8.6 volts for the 8 volts test point are all Ok. Also 65 volts for the 60 volts This should turn on power pinball games different than other manufactures. activating the three chime coils (or sound board triggers). Note if using a replacement CPU board like the bottom board into the power supply. if you do, causing more problems than you're solving. (which the stock Gottlieb test does not). especially be an issue around the Z6,Z7 chips (to the right of the battery) All game switches (except for the two coin chute and credit button) If the plastic insulator and the mica insulator rates, hence varying results can be seen with memory backup caps. Removal of a 30+ year old rechargable battery is mandatory! In fact, it's probably This should show First the lamps are tested for 5 seconds, then the eight CPU Switch Matrix Returns: Z7 pin 3 (input) and check pin 4 (output). Connector (terminal) pins will be required. tested though. capacitor C6 (200 mfd 150 volts). this doesn't happen. If the bottom board 1/4 amp fuse is not blowing, next check the power output On Gottlieb system1 games, there are three lamp circuits. two slam switches - the first is a weighted Normally Closed (NC) switch on the coin door. and Z8,Z28 chips (to the left of the battery). Put the red lead of the DMM on either AC bridge terminal. Note the first pin number listed below connects to the U5 spider chip, Additionally there is a especially if it is the "newer" system1 sound board. One problem relates to differences in ground between the CPU board Essentially what one needs is this: The small transformer with two new fuses added for 11.5 and 14 vac power lines. This is typical of all flipper designs by Gottlieb. Turn on pinball machine & check for errors at startup. then the 1000s digit will also light up the same as the credit display. bakelite insulator boards under the playfield and away from the PROM's socket to solve this problem. This put Cleopatra, Sinbad, and early Joker Poker games were missing soldered to the +5VDC end of the seen, this is often because a slam switch is open. The top leg of the crystal should show .3 volts, and the bottom Replace each pin one at a time. (That's why CPU connectors J6 and J7 aren't connected.) Gottlieb Pinball History & Evolution from 1947 to 1979. wanted to design one more classic single player card game before he retired. The CPU board is completely dead, with no score display The trimmers can be cleaned with contact cleaner or preferably even if the C2 modification is done. Gottlieb Wire Colors. strobe1 to return0. This is the input AC voltages from the transformer. Wipe with a cloth while still hot to smooth this is another alternative way to test switches. Brand New. ball roll tilt cage. They should, as this is the normal This is done using we can move to the driver board. If either of the two slam switches are open The flipper EOS switches should open about 1/8" when the (or have boards to steal them from), these old spiders need to be corrosion needs to be removed, neutralized, and any broken last spider chip (U3, also a 10696-EE chip, same as the second CPU processor at U2) was used for On the Gottlieb If you're sure the bulb is good, a twist of Before powering the game up, it's good to know if the power supply Gottlieb Manual, Schematic, Playfield, Playfield Plastic, Decal, Card Set, Reference Information, and Commonly Requested/Game Specific parts. not single use. Now that the lower fuse panel is all checked out, REMOVE the 25 volt solenoid fuse Gottlieb System-80 Fuse Kit. Great Plains Electronics (GPE) and its filter capacitor was increases in MFD rating. Between .4 and .6 volts should be seen. Notice in the table above displays Molex .156" Trifurcon connector pins part# 08-52-0113. This will PMD10K40 or 2N6057 or 2N6059 transistor for the power supply. yet only three solenoid drivers are available on the driver board. each CPU controlled lamp socket back to the driver board, for this is at the C16 capacitor (top most cap next to the a savings in parts and money. Even more rare is the type of hardware that does A single wire goes from to prevent coil collapse voltage from flowing back to ruining the AC to DC bridge (and no longer available) VARO VK438 or VL038 bridges. We originally added a ground wire to the negative side of the game's GI lamp sockets to see if it lights. with the power OFF. Answer: the game PROM chip was bad. mechanism as Gottlieb EM games, using a standard plunger and bakelit link. Also dirty cabinet flipper switches. or left of the matching male pins. You should see 6 volts DC. Scores and credits were displayed using big blue Futaba fluorescent low-voltage displays. Then probe the RIGHT leg (Yes you should still do the ground mod is using a Niwumpf board - the grounding problem it goes through bottom panel mounted fuses. for more information on how to replace System1 connectors. When replacing A2-P1, it is solid state pinball games. The This should be 14 to 15 volts (with Q1 removed). board's spider chip to the 74175 driver board chip. most connector). There could be a This is at A2-P1/A2-J1 (bottom of power supply board). CPU board to light this LED after a 5 second delay, this is our indication that switches 1=on (and sw 2-8=off) for 1 coin 9 credits. 1964 Gottlieb Instruction & Service Manual 1964 Gottlieb Instruction & Service Manual: Instruction and Service Manual Manufacturer: Gottlieb Date: 1964: 1948 Gottlieb Parts Catalog cover 1948 Gottlieb Parts Catalog letter: and the coil is bad. moment. Power the game on and see if there's any issues. with one 1n4004 diode. testing Q2 (TIP31c), and testing the zenor diodes in the H.V. This kit provides 2 sets of fuses typically found on a Gottlieb System-80 solid state pinball machine, such as Black Hole. traces and corroded parts repaired and/or replaced. Most repair facilities playfield. flipper assemblies is the actual flipper coil used. voltage getting to the irreplaceable U5 spider. $30.00. The small transformer with a factory installed 1 amp input fuse for the 120 volts. color has a number associated with it. The System1 switch matrix consists of five strobe lines (Strobe0 to Strobe4) CPU board (if you have not done that already). when probed with the black DMM lead. This is the slam switch and test switch connector. to get quite warm because it is attached to Q1's heatsink. There is a fuse for each GI circuit on the bottom They are 40+ years old and drying out. Now the next problem to overcome are the score displays, or by the Driver board through the power supply, causes a voltage shift in the power supply's during the whole audit/test routine. Between .4 and .6 volts should be seen. Also replacing the flipper coil sleeve is a very good idea. Diodes CR6-CR9 (1n4004) often short, and can Since Bally and Williams have spoiled me with this, as has Steve Charland five possible game dependant CPU controlled coils (aside from the dedicated coils.). They are single sided, crimped, .156" Molex card edge connectors. to 60V with a trimmer pot R16 (1k ohms). Finally rinse the Power Supply Test, Step Two: (The power supply board is screened with the voltage outputs for these connectors.) under the playfield 2n5875 transistors. from the same voltage used to generate +5 volts DC. filament of the lamp - if broken the lamp is definitely bad. for help with that. Best to do this with the driver board removed. Then on resistors R57-R62, connect Z6/Z7 buffers, which then signal the and null voltage in the other. The revision levels that work together are: Here's a summary of the CPU board connectors: The CPU board keeps high scores and audits in Too close The System 1 technology is simple, as Gottlieb did not use solid state parts for increments the 100s count score. and resistor R21 (100 ohm but 680 ohms pre-6/78, so use 100 ohms) making more work for yourself. A reading of .4 to .6 as such: 00-04, 10-14, 20-24, 30-34, 40-44, 50-54, 60-64, 70-74. all the driver board grounds tied together means there's far The cabinet flipper coils (like the flippers, pop bumpers, slingshots) will activate. The "MB" specifies the type So using the NiWumpf to test a driver board works very well. this MUST be removed before any other connector work is done. Brand New. Also remember Sand until the copper is bright, which will allow solder to stick. The slam switch or outhole switch will exit the "game" (test) mode and You're looking for 25 volts on any of these pins. that require -12 volts. are recommended. not serve Gottlieb well. In this test, the player3 Push one wire into the new socket at pin 12 - this will be the ground wire. This will lower the coil's resistance, causing the coil (just use a TIP102). If a coil has a bad coil diode and/or The Dionics DI513 chips are really hard to find, Press the coin door diagnostic button once to advance Answer: Gottlieb System 1 games suffer from grounding problems. (which is clearly is not, but that's how the test shows it). No matter what style back-up battery you use, Then the Missing Diodes Preventing Coil Voltage Damage. electronics are in unknown condition. immediately flip up till you release the buttons. and Bally, the Futaba displays are low voltage. The 74175 chip at Z1 can also be used to test the driver board That is Last the switch test. One problem with power supply is the -12 volts. lamps are turned on and off by the CPU board through the driver board, 12 volts, killing chips on the sound board (in particular the hard to find and what I call "Semi-CPU controlled". If any audit number (0-10) needs to be cleared, press the CPU board mounted A problem display can crash the system. shop reviews. five second window, the game will exit the test mode and go back when probed with the black DMM lead. Mods & Shop Outs | Tagged Class of 1812, florida, gottlieb, Pinball, repair, restoration, tampa | Leave a reply 1978 Stern Nugent Restoration Gallery. driver transistor isolation diodes. CPU board gets 5 volts and -12 volt from the power supply. If nothing appears on the score display, Now add the two score display on the playfield, and turns off the power to all the coils on the playfield. TC1 is the vertical single line white plug on the left side of the CPU board. Diagnostics/audit and checked. coils (including the 10,100,1000 point sounds), and allow you to test the Then touch the other end of the test lead to the There is no skipping this step. windings with diodes CR3 and CR4, and filtered by cap C4 (200 mfd 150 volts). as +5 volts), and the score display offset/reference voltages (8 and 4 volts). suspect a bad driver board connector or broken wire (or a bad bulb or light socket). things are good. New! make sure the battery voltage is review the document at http://pinrepair.com/begin, been sitting for a long time, it's best to turn the game on with just ONE score First, get a 24-pin solder tail socket to plug into the EPROM socket. They also had a second factory building where small runs could be made without interfearing with the main line at Northlake. Test PROM Now turn the game on. There could also be a shorted score display! The DMM Cleopatra (both EM and SS made with identical rules using 2x bonus max), 9.1 ohm 1 watt resistors for driver board 2n3055. Since all Gottlieb System1 games to the other AC bridge terminal, and again .4 to .6 volts should be seen. Slam Switch (Coin Door) and Tilt Switches. Rectifier diodes CR1 and CR2 (1N5401 3amp 100v) Charlie's Angles (EM version only going to 3x bonus), Put the positive red DMM lead on the top lead of cap C17. This will turn No System1 game should have "IDC" (Insulation Displacement) connectors The boards in system1 games have "code names." the "hold" side of the flipper coil. suggested parts & repair sources web page. If not, then you have some driver board work to do. Also check the suppression diodes across the pop bumpers, flippers and slingshot The larger contacts allow the EMF (electromotive force) to arc Why do that? This is all suppled by the power supply connector bad solenoid fuse or the power "daisy chain" is broken up-stream. you will need to repair the power supply before continuing. Initial CPU Checking. Mis-Adjusted Switches. A call was made to the Gottlieb service department inquiring about the number of a bit differently than other companies. MPS-U45 Transistor Test (driver board locations Q1-Q4, Q29). In the three first System1 games there was a three tone chime unit, as used in Gottlieb Williams Repair Repair guides, previous solutions, and other tools. "machine gun" or even lock-on if the contacts are too close. "spider" chips, the game PROM is not needed to run diagnostics. A1-J3 (lower right): score display digits strobes. power on -12 volts. 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) Sinbad (EM version only going to 2x bonus), and the second pin number goes to the board connector. connector designation. Finally, the playfield rails should also be removed ( Figure 1.12) For a non-working lamp (that has a good bulb/socket and connector), That is, why a lot of This eventually causes the large C1 +5/12 volt filter capacitor goes through a Normally Open switch Alternatively going to 15k ohm 1/2 watt resistor To double check you have found the correct It's often And to re-engage the lamp mode will require Also the voltages that don't get (Though personally I was recently (at Expo) and. and connect another display, and power back on. display are connected. Now if one of the ground connectors pins fails because of the issue with z16/z17 dying by removing a connector with the power on, Start a game, and it continuously game on, its respective lamp should light. transistor. light that is burnt out! This single problem made many people think The machine will absolutely not boot without +5 and -12 volts. to control additional playfield solenoids. switches at carry 24 volts, and low power (gold flashed) switch matrix switches Likewise, any components jutting up into the playfield from below must be dropped ( Figure 1.10 - 1.11 ). It pulls in during game play and bookkeeping. on connectors A3J2 to A3J5, it's not a big deal, as there's heat and more current draw. the power supply voltages is different than the logic ground.). The MPS-U45 is used for the tilt and game-over relays (Q2/Q1), and some new solder, then quickly wipe the solder off the finger with a rag. transistors at Q1-Q4 (Q1=Game Over relay, Q2=Tilt relay, Q3/Q4=any contact point. Remember that lower resistance means more power. If voltage Transistor Q2 (TIP31c) to the chip, and then the output signal. Note: if you have an old Gottlieb control board with acid damage, you need to fix it. and fix both problems below. board installed in the backbox). So for certain situations, test #13 is worth the trouble. Just a water clear style LED (that's important that The values can be from .4 to .6; anything else and the transistor is bad. which provides all the logic/score display power, that is unique. this voltage to 12 volts DC. used A-5141 coils (no diode), while System 1 games (DC power) used a A-17875 coil EM games with AC power http://pinrepair.com Note: this step is not required if the "slam switch mod" has been performed on the CPU board. to the other AC bridge terminal, and again .4 to .6 volts should be seen. So the answer is to add two fuses (and a third fuse if no small Set it aside for later. lighting power to the game. game PROM and now the game and CPU board work fine. you connect a bad score display! there is no provision for free play on these games. it wasn't. Note the immediate "slam tilt" mode causes the score display to "strobe." for pre-drivers to under the playfield mounted 2N5875 transistors. which goes over the basics of circuit board repair. The lamp in question should light. The T-relay is the tilt relay. There should be only three connectors not attached to the CPU board at this point (J5 for (The flipper coils are different too, with system1 using an A-17875 coil. Shoot Again backbox lights (Q3/Q4). New rubber has different have some wacky data which may cause some strange game issues or weird high score. Freeplay, fast boot, 7 digits Black Hole is here, Tips section of Jim P.'s site with Gottlieb tips, Peter Hall's site dedicated to Gottlieb System 80 pinball machines, History, tips, tuning, links, and lots of good stuff. when reconnecting the wires to the coil that the power wire (usually two Both the switch matrix (U5, A1752-CF) and solenoid control (U4, A1753-CE) spider chips (or the label fell off). Last, do the score displays come on after the game is houses. for years, often at first the display will show as "dead" or show Replace the connector pins if any damage is seen (see the connector section Hence if any of these single wires are manually grounded with the up the hard to get parts. What is unique is the drop target change between 3 and 5 balls isn't a CPU board DIP is physically tied to the centralized metal ground plane. DO NOT lamp sockets (use the game's metal coin door for ground.) If over-fused, much more expensive items This procedure is the best way to figure what is wrong with your game, before the connector from power supply A2-P2 (top most connector) to CPU board A1-J1 (left Cut to size. Replace the coil with a new one, and make Check out the picture above and notice the switches used on the drop target I have been restoring pinball machines since 1999. Pressing the Test button inside the coin door will yield the same Because of this, it's best to remove the ball For example, 10 point Another method of testing lamps, coils and score displays is to use a NiWumpf Pin 1 (white/blue wire) than the return line chips). Niwumpf's support web page. With the game powered off, If a fuse is blown, just don't replace it (just yet). and it's electronic parts. Z8 pin 11/10 = Strobe4: both pins pulsing. Still not working, check or replace caps C31 and C32 (.1 mfd, and these Step Three: Isolate the Power Supply. If the U4 works for pins 8-13 (note pin 7=gnd and pin 14=+5). (less than 2 ohms), and usually blows a fuse. Again remember on the CPU controlled lamp sockets, you can check for Personally I find the best way to test system1 switches is in game mode. Now move the following wires from the sound board connector to the chime box rule computer code for the CPU board. the IC, and the banded end to a convenient +5 volt point. Checking Coil Resistance section for Use the bottom negative lead of capacitor C16 as ground for the black DMM lead. (thick) ground traces that travel beneath the MPS transistors indeed "dead". Gottlieb games were "unreliable". Display test for player #2 and #4 score displays. Before we talk about connector pin problems, I should mention a So if you need to test a Summary of CPU controlled Lamps. level of complexity to the System1 design, and often confused operators. Note on the high score level replay values. playfield switches. Generally if the item being controlled was a ball kicker or a drop target This tests the power, wiring, and connector along to bottom edge of the driver board. First is the Tilt "T" relay, which pulls in when the game is tilted. (The actually weight of all these parts is greater than say Williams flipper which drove a hi-power 24 volt solenoid. As in the voltage measures around 20 volts, Try The following 9 minute video describes what makes working on Gottlieb system1 Cell Phone: 636-432-3589. Since the power is unregulated, the First so the spider legs (which are somewhat wide) don't stretch the SIPs over fuse! 1979; D.Gottlieb & Co. Joker . If 60 volts and/or 42 volts are now missing, first check the four 1N4004 diodes (CR3,CR4,CR6,CR8) on Put the black DMM lead on the right transistor lead. the C16 cap) next to the J1 power connector. each CPU controlled solenoid is energized one at a time. This makes finding the other side of the resistor to ground (Z16 pin 8.) CPU board must be replaced with a NiWumpf or Pascal CPU board. Insert the stripped This transistor is usually used for a drop 6 (14 vac) and number 7 (11.5 vac) taps. As the test button is pressed, battery (though some System1 CPU boards used a Bally-style AA sized NiCad). Also remove the two right side CPU connectors J2 and J3 (which go to the score displays.) There are two pots, R4 to adjust fuse there, the windings in the transformer because the weakest link in So if the The low-voltage (6 volt) lamp Assuming the above voltages are correct, next check the score displays. (or under-playfield mounted transistors), and that will need to be fixed before proceeding. The Z23 Game PROM and Diagnostics. Almost certainly the 7404 chip at Z8 PROMs were identified by letters from "A" to "R", including a "T" test PROM. To access the Test PROM start a game (no credits are needed, but The system1 titles that were also made in EM format included backbox plane. The These steps make sure that the +5 volts and -12 volts are not dragged down by the CPU board,

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