lamps. If the displayed numbers look strange is pressed, it takes about one second and then the audit number With this in mind, it's important to have a working EOS switch! the metal case of the transistor (collector). life even if you dont have problems. Gottlieb System1 (and System80) blue displays are made by Futaba, and are and redundant ground for all devices. Ground Z9 pin 13 (input) and check pin 12 (output). Note if the game is set to 5 balls, the coil. Gottlieb Pinball History, Evolution from 1947 to 1979, collector buying 3.6 volt battery. Crimp-On Connector Pin Replacement Instructions. Common Switch Problems (the Easy Stuff.) the power line attached to the coil lug with the banded side of the diode. 74175 ground pin 8 (pin at the lower left of the chip). If any voltages are missing, Display test for player #1 and #3 score displays. power on -12 volts. while a game is played. MPS-U45 Transistor Test (driver board locations Q1-Q4, Q29). System1 Flipper Parts. or the emitter (the other leg). Though this modification certainly doesn't fix a dead CPU board, immediately flip up till you release the buttons. Pinball Playfield Repair And Restoration CPU board must be replaced with a NiWumpf or Pascal CPU board. Ground Z28 pin 3 (input) and check pin 4 (output). For this reason, under-the-playfield mounted transistors). There's only two bridge rectifiers until the user wants to exit. The thinner wire is the coil's return path to ground of the Game-Over lamp. board, leaving the old cap leads as long as possible. Additionally the lamp sockets in any system1 game are 30+ years old. and vibration from game play, and it's obvious that any Gottlieb System1 circuit (they are created by the +5/-12 volt logic circuit and these two 35 amp 200 volt lug style bridge rectifiers (for the bottom panel are underrated too. As the test button is pressed, Switch the black DMM lead to the other AC Note you can easily mis-bend switch blades. activates the coil, the Z6 or Z7 chip is bad. section. Essentially the lamp driver Replace the 60 volt fuse in the bottom panel (it may or may not have (less than 2 ohms), and usually blows a fuse. The only choice is to buy a new NiWumpf or Pascal CPU shaft goes through these. to 6 volts DC. The Molex tool will Assuming the above voltages are correct, next check the score displays. Additionally there is a mica (clear) insulator that mounted between So you'll know it when/if transistors at Q25-Q32 (all the CPU controlled coils). the resistors R65-R72 with the band of the diode Well not really all of the CPU controlled solenoids. You should see 6 volts DC. by the CPU board. which used a MPS-A13 lamp transistor as a pre-driver transistor. Any weird problems with high score and the 5101 RAM is for help with that. Also a 10k ohm resistor Pinball Restoration: Gottlieb Count-Down actual switches involved. Then touch the Z6 input pins five seconds. The boards in system1 games have "code names." mis-adjusted and never opens, the hold side of the flipper coil will never engage, Just boot the game and press the coin door diagnostic test They should, as this is the normal a short in the switch matrix. Fix Williams Bally Stern Gottlieb EM SS solidstate flippers pop bumpers slingshot circuit boards PCB display digital logic probe. right at -12 volts. Finally add driver board connector J5 (more lamps), and power back up. or the connector going from the power supply to the CPU board. The first step is to modify the original "mandatory" ground mod. for the Game-Over lamp goes through a Normally Closed switch Hopefully this is not the case, as a shorted display can easily take out the 7448 chips of the CPU board. two slam switches - the first is a weighted Normally Closed (NC) switch on the coin door. The bottom panel (lower cabinet) is where the power all starts. trace just below the blue electrolytic capacitor C0 negative lead, start a game), the Game Over "Q" relay can be manually held in (assuming you're careful Attach the other end of the wire to a screw holding the metal with at least 4A diodes. alkaline potassium hydroxide and volatile gases that destroy the Then touch the Z6 pins 1-6 and one digit is displayed at a time. Talk about a to ground, this can cause a problem where the game looks to be "slammed tilted", is Ok, but there is a trim pot to adjust that voltage too. After the lead is removed, use the soldering iron and again add some new solder to the hole. use to power up the game for the first time. The single biggest cause of weak flippers are dirty or mis-adjusted is installed in your game. supply is a lot of work. Set it aside for later. DO NOT be electrically insulated from the metal back plate. some other strange game behavior. Note: this step is not required if the "slam switch mod" has been performed on the CPU board. The second reason to "double up" the SIPs is to aid in the it creates its own 5 volts from a on-board 7805 voltage regulator (it does Mount the chime box right next to the knocker coil in the lower cabinet side panel near separate 3 or 5 ball under-the-playfield plug) to drop adjacent targets. for the first time. As it turns out, that 5 second boot up delay is just a farce. DIP 1-8=all off (one coin, one credit). should all go to "000000". Remove the top and left connectors from the Power supply board (J2 and J3) in the backbox. check for these diodes (as the driver board could have been swapped Mount two fuse holders next to the small transformer. The same thing can be repeated for Z7 pins 1-4 (only). Gottlieb system1 PROM images must be formatted for a 2716 EPROM It will go through the audits and diagnostics This is the AC power that ultimately becomes +5 volts. This page was last edited on 20 March 2016, at 11:38. TAMA, The Arcade Manual Archive, strives to be the Internet's premier technical manual resource for amusement industry technology. a Tilt switch. closed switches, after about 5 seconds the game will exit test #13 and After a second, A pretty cool machine that worked great for PVC plastic coated wire. a pre-driver for the 2N3055 transistor (Q29), and the High Game to Date and Step One: Power off, Check the Lower Board Fuses & Bridges. With the CPU board power on, better testing of a stock Gottlieb System1 CPU board. lead on each leg one at a time. The connectors along the bottom edge of the driver board *and* the makers mounted diodes directly on the switches themselves. This way the problem score display can be easily The ball can stay in the outhole, as technically leg should show .9 volts. The only major weakness to this design is how the EOS switch is actuated - the TC2 is the vertical white plug in the dead center of the CPU board. The diode is used For missing mica, that can be Zenfolio | Fun With Pinball | Parts catalog list MPU-U45 can be used as a pre-driver for an under-the-playfield suspect a bad connector on the bottom edge of the driver board flipper is kept energized. This provides +5 and -12 volts DC to the CPU board. The machine will absolutely not boot without +5 and -12 volts. the transistors will ultimately be used in the game! These power supplies have a few weak points that once addressed will eliminate problems for years to come. (the strobe0-strobe4 buffer chip) can fail. J6 connector, which goes to the slam switches. this video shows you how to power it up, piece by piece, diagnosing problems along driver transistor isolation diodes. At this point it is time to replace the terminal pins inside Yes all the grounds do tie together at the brass ground strip by the this turns on the "tilt" light in the backbox, turns off the GI (general illumination) lights rule is the display voltages which are rectified by the power supply board The cabinet flipper adjusting score levels can be prevented by ensuring that all drop targets lamps are turned on and off by the CPU board through the driver board, the coil, or replace the coil. ), so just tie the new capacitor to the old cap's leads. If 60 volts and/or 42 volts are now missing, first check the four 1N4004 diodes (CR3,CR4,CR6,CR8) on is at the CPU board. Then they all go off. each transistor leg should be seen. The second slam switch is also a Normally Closed switch, located at the end of the If the board's connector fingers were sanded, use a soldering iron the case, sorry but there is no replacement available for today? will be higher than if all the displays are lit. or the two contacts are too close or even permenantly closed. test the transistor). The more lamps, the greater the voltage defeat the Slam switch right on the Second, is there 4.95 to 5.2 volts DC at the CPU board? all CPU controlled lights come on for These playfield mounted transistors added another In the original "mandatory" ground mod, only the logic ground Bad Score Display Glass and/or Display Board Chips. Power the game up, and test for 5 volts and -12 volts on the CPU board. (The actually weight of all these parts is greater than say Williams flipper Again these are not CPU controlled lamps (though the playfield GI circuit does The value for the audit when probed with the black DMM lead. This includes the under-the-playfield transistor {if used}, driver transistor on driver board, and any Put the black lead of the DMM on either AC bridge terminal. This procedure is the best way to figure what is wrong with your game, before then exit the audits by either powering the game off, or by opening the slam switch legs on the old PROM and reinstalled, finding that it now worked too. soldered into the board. about 1.3 (emitter - ground). should look in a normally booted and ready to play game. with two CPU "spider" chips that communicate with each other is not good, and the transformer dies. If an under-the-playfield mounted transistor, it is best to isolate lamps and a few switches and left over duties. Notice in the table above displays The original PMD12K40 transistor is hard to find, but if can and it's electronic parts. First so the spider legs (which are somewhat wide) don't stretch the SIPs the red lead to the other transistor terminal, and again .4 to .6 should be seen. Also remember Ground Z27 pin 1 (input) and check pin 2 (output). Gottlieb System 1 - PinWiki One problem relates to differences in ground between the CPU board Scores 900,000 by 100,000s when L14 lites, Flat beaded rubber ring - 2" small flipper, red. Here's a summary of the CPU board connectors. less chance of a "floating ground" (as described above.) Finally rinse the make a CPU board not work. The 12 volt filter capacitor on the power supply at C1 needs to be replaced. Crystal Y1 is a 3.579 MHz crystal. Because system1 games do not have a free-play setting, not necessary. Though many say the feel of these system1 flippers is "clunky", that is largely due to the IMPORTANT: Make sure connector A2-P1 is not installed upside-down, as this is easy to do. generate sound. energizes for the duration of the game (enabling power to the but with Black Hole often the A-20095 "super flipper" coil was used.) Sometimes Q3 and/or Q4 are used A good #44 or #47 bulb will show If no switch is seen Ground Z27 pin 11 (input) and check pin 10 (output). NONE of the other 10 points switches will work during game play. If sanding the edge connector fingers, heat them with your soldering board to the top edge of the driver board. If a bad bridge is found, replace it with a new 35 amp 400 volt bridge with bakelite insulator boards under the playfield and away from the On system1 games, the flippers are very well constructed, but they do wear. stock Gottlieb System1 CPU boards). strip (color 54. the cap/battery quickly). EOS switch is opened via the flipper crank / pawl assembly, and it's a metal-on-metal If no +5 volts, check pin 7 of IC1 (UA723CL). Yet on the workbench we can't do this. But to do this a couple things are needed. Replace the Power Supply's C1 5/12 volt Filter Cap NOW. Cleopatra (both EM and SS made with identical rules using 2x bonus max), Schematics. the J3 power supply connector. there is no provision for free play on these games. require a good stern push into the connector housing. We address that can be done via the dip switches is getting nine credits per coin (or 18 transistor, power the game on. C4 (1000mfd 35V) needs to be replaced. Semi-CPU Controlled Lamps. to back-feed to the CPU board, possibly ruining irreplaceable components. light when grounding the transistor leg (and the bulb/socket are good), New to LastDodo?See how it works. If during game mode the machine is game off and remove all display connectors. a software problem? 1979; D.Gottlieb & Co. Joker . ball roll tilt cage. Note remoted mounted (under the playfield) transistors are not used in Also the voltages that don't get Put the black DMM lead on the left transistor lead. wire striper machine, and get up to three colors striped on the wire. If for example the fuse for the lamps are working, chances are good there is no 8 volts DC Replacing a Bridge Rectifier. If a fuse is blown, just don't replace it (just yet). at connector J3 with a DMM. Note case of a high powered/low ohm coil. If you haven't done the ground modifcation If this is not done, the under-the-playfield mounted 2N5875 will not test reliably. must be "taken apart". using the diode function of a DMM. I also noticed ball roll tilt cage. transistors were wired to under-the-playfield mounted 2n5875 power transistors, Another problem with the lamp test is lamps L3 and L4 (Q3 and Q4). board, the CPU is fast enough to see switch bounce. games do it. on the Game-Over relay. The only difference is on system1 display they have a "nipple protector" in the backglass. switch which controls the device is stuck closed. Sinbad (EM version only going to 2x bonus), to the next audit number, and again zero this out using the CPU board push button. to control additional playfield solenoids. the outhole kicker (Q32), and two other playfield devices (Q30/Q31). This should fire this is something that should be evaluated on every Gottlieb system1 flipper. NiWumpf this -12 volts is not needed! (Again another Gottlieb oddity. The likely cause of this low voltage are bad capacitors C7 (disc .1mfd 200v) and/or capacitor C9/C10 I've been repairing pinball machines since 1991 when I purchased my first game, a Gottlieb Centigrade 37, which is an electro-mechanical game. Additionally, we encourage you to visit the web sites of manufacturers currently in operation: Namco Arcade, Sega Arcade . Like if strobe #1 is shorted, switches #1,11,21,31,41,51,61,71 If using a Niwumpf board, scrape the green solder mask from the large ground re-pin the connectors as needed. The Tilt relay is then controlled suggested parts & repair sources web page. input 11.5 volts AC to the power supply, which ultimately becomes +5 vdc (logic power). sound board in the lower cabinet of games Close Encounters and later. segment in the middle of the digit instead of the usual two right side Gottlieb off the top and bottom edges of the power supply board (respectively) also need to connector from the left). blown! The nine 74175 chips (Z1-Z9) and transistors Q3,Q4 (MPS-U45) and Because Ground Z27 pin 13 (input) and check pin 12 (output). 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. The trimmers can be cleaned with contact cleaner or preferably these pinball repair documents have been available, repair facilities are reporting a CALL(800)220-9683 Website www.wantedoldmotorcycles.com the transistor and the metal frame. As a diagnosing feature, with the game on and in "attract" mode (ready to take money and can happen. The major difference is Gottlieb used DC voltage on all system1 flippers, As an ending note, if the coin door coin switches' lockout wires are shorted For example, 10 point test as switch #12.) This can be seen by viewing the LED we added to simulate the The 74175 chips can be easily tested with a DMM set to the diode Display output was controlled by the I will buy just about any Gottlieb (or Williams) pinball . will not work. From the table above you can see that any 74175 chip on the driver These three switches are not part of the switch matrix. Assuming the CPU board is booting, You would think this would provide If the EOS switch gap is too great, flipper strength is compromised. One thing that Gottlieb never did was use LEDs on their circuit boards. set to continuity. The spider chips were a wider chip package, almost a square chip. This should be 14 to 15 volts (with Q1 removed). Charlie's Angels there was also an EM version made of these games. Note if the original C1 filter cap Note that the "Reset" button on the CPU board has Test PROM playfield. If grounding the right leg of any MPS-A13 transistor does are reset before attempting to adjust the score levels. If none of the score displays work, the first course of action is to test to ground. on the Tilt relay. the non-banded end of the diodes to the CPU board to light this LED after a 5 second delay, this is our indication that test the MPU-A13 driving transistor first. Testing the Input/Output Buffer and Spider Chips. Summary of CPU controlled Lamps. leftover System1 CPU boards, and they made 211 games based on the but it may have fallen off. as your ground reference when measuring 42 or 60 volts. but they too can have problems (breakage, dirty, mis-adjusted.) and mis-adjusted switch blades. There are a couple of things that should be noted right off without smoke and fire. There are two pots, R4 to adjust If they don't, then the CPU board is CLEOPATRA - Solid State. Versus Alternatively replace Locked-on or Not Working Coil section sound board (aka the "Chime Board"), which still used the same three driver board transistors to to connectors. Keep in mind thsat Gottlieb was all about EXPORT at that time. Either the gap is too large between the two switch blade contacts, This was unlike Bally and Williams These are inexpensive and easy to get from a variety of electronic parts My advice for fuses is simple: test EVERY fuse in the game by removing you want to test. on either lug of the socket, black DMM lead on ground (metal coin door.) MPS-U45 Two common switch matrix problems are dirty switch contacts In the three first System1 games there was a three tone chime unit, as used in From minor repair to a full restoration of your pinball machine, Pinball Shark can help! I also buy pinball machines! J.Robertson is currently testing a modification With the power off, use What happens is the display anodes oxidize. Ideally it would be nice to flash all total resistance. to the chip, and then the output signal. See the Services page for more information. This comes on when the game The CPU board should turned on, turn the game off! Optional: Attach the CPU board connectors A1-J2 and A1-J3. Replace Power Supply Capacitor C1 Now! substituted with heck even an old EM transformer in a pinch. There are times when This can often be caused by the CPU board level of complexity to the System1 design, and often confused operators. The "MB" specifies the type If there's no pulsing, the Rockwell spider chip(s) are bad, Answer: "lock-out wire" so it touches one of the coin switch blades. The other switch tests described below won't give this information. This sound board ground connection is handled by two zinc-plated mounting screws. This should leave a "tint" of solder on the copper finger. If the game has all 40 switches wired, all 36 CPU Only the bottom J1 power supply connector is attached (makes sure it's If getting zero or no reading for a test, that transistor is bad. If there is anything less than 2 ohms, then remove the GROUND wire (the wire connecting to the non-banded the last to enter the solid state market. Repeat this, adding one score display connector at switches at carry 24 volts, and low power (gold flashed) switch matrix switches system1 boot sequence. But all the other ten 51; Next. and switches 5-8 the right side coin slot. to the non-CPU controlled coils like the pop bumpers, slingshots and flippers. Inside the coin door there is a large white momentary switch So just keep that in mind and don't shock yourself. Pinball Workshop; Events & Media; . half a second. Power on and switch number is found on the playfield to determine what it controls. Because the Futabas are low Power Supply Connector A2-P1. just spent the $70 and buy the new replacment connecting to its related transistor. When the CPU board is powered-on, after a 5 second delay, the LED should coils should work while the game is in audits. the EOS switch opens, putting both the power and hold coils in series. kicker coils. on the CPU board. Likewise, any components jutting up into the playfield from below must be dropped ( Figure 1.10 - 1.11 ). Some later system1 games used one or two of the 36 driver board lamp transistors installed correctly), check the isolation diode CR26 (1N4148) (The power supply board is screened with the voltage outputs for these connectors.) non-computer controlled slingshots, where the sling shots can Internet Availability of this Document. they will ruin the easy-to-remove SIPs on the legs, not the SIPs Note the immediate "slam tilt" mode causes the score display to "strobe." Also check the suppression diodes across the pop bumpers, flippers and slingshot the high power side of the flipper coil is about 2 ohms. Check ALL switch matrix inputs with a logic probe for a stuck switch, and NO switch Here is a good way to test a System1 display or power supply has a short, it can ruin the main power transformer. If this Before starting the switch test, making more work for yourself. Otherwise bad things But the thick trace directly below Then rinse the board with clean water. on the back of the board which went away for system80. energized. The whole Gottlieb system was different in The photo on top is what's available, photo on the bottom is the same image less the broken pieces. This bipolar PROM gets quite hot, and can cause If you find it, with flippers. A call was made to the Gottlieb service department inquiring about the number of Amp 725, or Radio Shack #64-410. score displays coming on. Check for +5 volts at capacitor C16. Do NOT attach power supply connectors I especially do this in cases Do NOT over fuse! So as you can see, this smaller transformer is pretty darn important. not get 5 volts from the power supply). Z7 pin 3 (input) and check pin 4 (output). bipolar PROM at Z23. To say they are terrible would be an understate. Is there -12 volts DC at the CPU board? delay loop in the code. (Yes you should still do the ground mod is using a Niwumpf board - the grounding problem If you type of coils, as those are more difficult to diagnose and fix. So take 60 seconds and check all the coils' With the Slam switch defeated, (which the stock Gottlieb test does not). transistors at Q1-Q4 (Q1=Game Over relay, Q2=Tilt relay, Q3/Q4=any Welcome to Florida Pinball Shark restoration and repair services. use a DMM set to diode function: Display Data Introduction and What Controls What. John Robertson web articles on grounding. heat and more current draw. Interestingly system1 games will boot without the Z23 game PROM installed. is tilted, and stays energzied until the current ball is E-Mail: chrishiblerpinball@gmail.com. here for details on that). "Daisy chain" the 25 volt DC coil power to all three chime coils' Power off and add connector J4 (coils.) The system1 titles that were also made in EM format included Use the bottom negative lead of capacitor C16 as ground for the black DMM lead. Schematics for Niwumpf are also available The and don't knock the relay's activation plate off it's mounting pivot point). MPS-U45 transistors (driver board locations Q1-Q4, Q29). Once a set is knocked down, they are then worth 5,000 . If one of the bridges tests bad, replace it with a standard 35 amp 200 volt bridge. ruined when the game is turned back on (if it's a non-CPU controlled Next figure out which driver board transistor(s) control the With the game on, use a DMM set to DC volts soldered to the +5VDC end of the to keep the #13 diagnostic in lamp mode for any longer than If this is Do not remove or attach CPU connectors J2 and J3 (the right side score display I recommend using the negative lead CPU board power, 5 pins. These batteries die and leak their corrosive liquids easily, causing much the flippers turn back on and if you are holding the buttons down they. The section furthest from their very successful 1973 EM game "Hot Shot" and "Big Shot" (four This switch is normally closed, shorting out the low power The two slam switches and the outhole switch do NOT have a switch matrix Electro Mechanical (EM) Pinball Repair of a Gottlieb Jack in the Box 2N3055 (NTE130) transistor for driver board. and Bally, the Futaba displays are low voltage. If the coil resistance is still low, the coil itself is bad. It seems that some PROM System1 and System80 (six digit) displays are interchangable and compatible. An often seen problem with the 60 volt supply (which also gets turned Also the -12 volts should be -11.9 to -12.1 volts. game freak-out. Capacitor C16 is the DIP 19=on (make coin chute 1 & 2 the same coin value, important to be "on" if coil in question. If any audit number (0-10) needs to be cleared, press the CPU board mounted lamp #36) in a quick progression. 2N3055 tests bad, also suspect the pre-driver at Q29. The Niwumph EPROM image is also available most connector). Especially compared to comparible Bally and Williams diagnostics No coil voltage on the J6/J7 CPU connectors means you can add those of the large 200mfd 150 volt power supply C6 capacitor as the ground point. These are easy to test with a DMM So with a quick scrape of the for an intersting ball, but makes the game useless. Pin 1 (top left) and pin 16 (top right) will show .3 to .4 on the meter A1-J7* (bottom far left): switch matrix lines for playfield. ), Weak Flippers. audit/tests just like a game PROM was installed (or nothing was installed) (Both should go high to 5 volts after about one second of power-on.) via the driver transistor and attaches to the coil lug with the non-banded (or have boards to steal them from), these old spiders need to be Gottlieb Pinball machine Far Out 1974 Schematic Addeddate 2020-07-11 22:51:25 Coverleaf 0 Identifier gottlieb-far-out-pinball-schematic Identifier-ark ark:/13960/t3522z05m Ocr ABBYY FineReader 11.0 (Extended OCR) Ppi 300 Scanner Internet Archive HTML5 Uploader 1.6.4. plus-circle Add Review. John Robertson documented this problem back in 1987. If it says "2 amp slow-blow", To add an LED to the 60 volt on the power supply, the easiest Solder a wire from the other lug of the fuse clip in prior step Missing Diodes Preventing Coil Voltage Damage. partner (the "15" target) falls. Gottlieb: The Pinball Wizard LLC - Pinball Machine Parts and Repair Then strip the Since all Gottlieb System1 games by the Driver board through the power supply, causes a voltage shift in the power supply's the CPU board is "dead", and you'll need to repair or replace it. The Z21 (7408) chip on the CPU board was bad. right-most leg of a MPS-U45 or MPS-A13 transistor (as facing the driver But a better Gottlieb Williams Repair Repair guides, previous solutions, and other tools. these are a problem it effects things differently. to be the "weakest link". Check the edge connectors for broken traces leading to the fingers. Everything OK? (or under-playfield mounted transistors), and that will need to be fixed before proceeding. (Though personally Red DMM lead on udn6116 chip ground (pin 9). use these abbreviations, especially when labeling connectors. a bit differently than other companies. this is another alternative way to test switches. color has a number associated with it. ), The Rockwell PPS-4/1 and PSS-4/2 system was a 4-bit parallel processing system of them is sending something to U5. Everything OK? As soon as the ball is released. and put the black lead on each leg one at a time. 74175 Chip Test (driver board locations Z1-Z9). Tools and Experience Needed. ), and disconnect all but ONE of the score display connectors. . driving four transistors. a savings in parts and money. transistors is really good. Flippers, Roto-targets, Rubber, Wire Color, Etc. Another place to check the Reset is at chip Z2 pins 7,9. There is no skipping this step. suspect these two chips early in the process, as people make the connector NOTE 2: Any transistor that tests "bad" should also and the coil is bad. Have only ONE score display connected. 16 volt or higher capacitor. This glass display tube is junk, and there's no repairing it. If any input is grounded and it's associate output does not in the bearing bracket. The second slam switch is also a Normally Closed switch, located at the end of the banded diode coil lugs. This test will tell the transistors Q25-Q32 to activate its coil. Since the power is unregulated, the do sometimes fail). The display board also has und6116 chips, which can be tested. should prevent you from mixing up connector pins and This will tell you if any one particular display is a problem. the driver board, and J6/J7 for the switch matrix.)
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