Repairing Bally Electronic Pinball Games
Scope. BELANGRIJK: De meeste professionele reparateurs nemen GEEN printplaten aan die door
eerdere reparatiepogingen vernield werden (gehacked) Speciale dank aan Leon Borré voor het schrijven van testsoftware waarmee
het opsporen van fouten flink vereenvoudigd is.
Table of Contents
De meeste professionele reparateurs nemen GEEN printplaten aan die door
eerdere reparatiepogingen vernield werden (gehacked)
Speciale dank aan Leon Borré voor het schrijven van testsoftware waarmee het opsporen van fouten flink vereenvoudigd is.
Table of Contents
1a. Getting Started: Experience, Schematics, Manuals.
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.
Schematics and Manuals.
1b. Getting Started: Necessary Tools
Non-Specialized Tools Required:
Specialized Tools Required:
1c. Getting Started: Parts to Have On-Hand
Parts to have:
Alle transistoren, ic's en overige componenten zijn leverbaar bij de Flipperwinkel in Arnhem.
1d. Getting Started: Game List
It is very important to know what generation of Power supply, MPU and Sound board the game has.
1e. Getting Started: Lubrication Notes
The only parts that will require any lubrication are metal-to-metal moving parts. There aren't very many in a game. Only ball eject and slingshot hinges. 3-in-1 oil also works on these if needed. But try and keep that lubrication in the tool box and away from the game.
If some prior person did lubricate the game, the lubrication has probably now congealed with the infamous "black pinball dust" to form a thick, black mess. This is unrepairable on coil sleeves, and new parts will need to be installed.
1f. Getting Started: The Circuit Boards
1g. Getting Started: Voltage Test Points on the Boards.
1h. Getting Started: Power Supply Power Distribution.
Rectifier Board Fuses.
2a. Before Turning the Game On: Removing the MPU Battery and Fixing Corrosion.
Can This Corroded MPU be Fixed?
The Repair Connection has a very nice web page dedicated to fixing battery corrosion. They explain the pitfalls, and the common mistakes made when attempting this repair. Check it out at http://www.repairconnection.com/acid_damaged_mpu.htm as this is an excellent document.
New Replacement MPU boards.
Can a Small Amount of Corrosion be Bad?
Buy a Bally Reset Section Repair Kit.
Removing and Replacing Corroded Components.
Step 1: Pry up the old socket base. If a black socket, it will come right off easily, leaving the solder-in socket pins in the board. The brown sockets will not pry up (don't even try!); skip right to step number three. On the black sockets be careful not to damage any traces while prying with the screwdriver tip! Once the socket base is pried up, examine the socket pins for any grey/green corrosion. If the socket pins are clean and undamaged, press the socket base back onto the pins.
Step 2: If the socket pins are grey or green, the entire socket will need to be replaced. With the socket base removed, it is easy to remove the old socket pins. The best way to do this is to heat each individual pin, and pull the pin out of the hole with needle nose pliers. It may be easier to heat the solder joints from the back (non-component) side of the board because the corrosion is usually less there, and the solder will melt better.
Step 4: Examine the connector header pins for corrosion. Pry up the header pin's plastic base on the component side of the board to see underneath it, and around the pins. If any corrosion is found, remove the header pins so the corrosion can be removed. Especially important is the J4 (power!) connector. But any corrosion on the MPU board connectors can cause adjacent connector pins to short together.
Step 5: Examine the DIP switches for corrosion. Any corrosion around the DIP switches can cause these switches to short together, giving all kinds of strange switch matrix problems.
Step 8: After the board is dry, sand the corroded area again with 150 grit sandpaper.
Step 9: Replace any damaged traces on the board. For large (thick) traces (like the ground rail surrounding the outside of the board), use desoldering braid. For small traces, use wire wrap wire. For medium traces, use stranded 24 guage wire. Use rosin soldering flux (Radio Shack) to help solder stick to copper.
Step 10: Install machine pin strip sockets, or some other high quality socket with an OPEN base (so the traces can be seen under the socket!). Strip sockets are the best because they allow complete access to the traces around the socket. HIGHLY SUGGESTED: solder the machine pin sockets from the top of the board too (cheap sockets will not allow this). Often the plated through circuit board holes are damaged, and the only connection between the traces on the top and bottom of the board is the socket's pins. Use rosin solder flux (Radio Shack) on bare copper to get the solder to stick better.
Often damaged copper traces are difficult to solder. Even after sanding the traces to a bright copper color, sometimes solder will not stick easily to the traces. To help with soldering, here are few tips:
Memory Back-Up Capacitors.
Installing the Memory Back-Up Capacitor.
2b. Before Turning the Game On: Rebuilding the Power Supply
There are three different version of the Bally electronic rectifier board. The most common is AS2518-18 (which is identical to the rectifier board used in Stern games too). This is the most troublesome design, and will require some upgrades. The least common is AS2518-49, and was only used on Kiss, Future Spa, and Space Invaders. This rectifier board also will need some upgrades. The AS2518-54 rectifier board as used in Xenon (10/80) and later is quite good, and requires no upgrades (other than possibly replacing header pins, if tarnished).
The Power Cord.
The line filter is the next thing connected to the power cord. It's a small silver box that prevents the game from making line noise (which could be "heard" by other products like stereos). Not much to go wrong here, but occassionally these go bad and short.
The rectifier board takes AC voltage from the transformer and converts it to unfiltered DC voltage. Bally used three different rectifier board in thier games from 1977 to 1985. The part number is silk screened right on the printed circuit board.
Prior to Xenon (late 1980), the actual power supply is in the backbox (head) of the game. It's usually located in the lower right corner (as facing the game). It comprises a large transformer, a silver platform, and a smallish printed circuit board known as the rectifier board. Most of the game fuses are located on the rectifier board (there is usually at least one playfield fuse too).
Power comes into the rectifier board from the line cord at connector J2, pins 6 and 7. It then goes to fuse F6 (3 amp slo-blo), and then to the transformer (primary). The transformer splits the voltage into five different AC voltages. Then these voltages run through their own fuse. Some of the voltages (7.8, 12, 49 volts AC) go to a 200 volt, 8 amp bridge rectifier which converts the AC voltages to DC (+5.4, +11.9, +43 volts DC respectively). The 7.3 volts AC stays AC, and powers the game's general illumination. The 173 volts AC that is used for the displays is converted to 230 volts DC by four 1N4004 diodes (CR1 to CR4).
If there is a AS2518-49 rectifier board, this works identical to the above described AS2518-18 model. The only difference being there's no 7.8 vac and no bridge BR1. Instead, 9.2 vac comes from the transfomer, and is converted to 6.5 vdc by two heat-sinked 200 volt 30 amp voltage regulators. It works exactly the same as the previous model, and has the same pin out (except for one extra pin on J1), but has a beefier +5 volt output.
Header Pins and Connector Pins on the Rectifier Board.
Trifurcon Connector Pins.
Check Rectifier J3 Connector Pins 8,17.
Bridge Rectifiers, Diodes, Voltage Rectifiers.
On the AS2818-49 rectifier board, bridge BR1 is replaced with two voltage regulators. These are R712 (NTE6200), which are 200 volt, 30 amp devices. This rectifier board design is heavier duty then the AS2818-18 model.
Note that the 49 vac that is converted to 43 vdc also has a varistor mounted in it's circuit too.
Power Supply "Test Points" (TP's).
If getting a voltage below the above value ranges, that associated bridge rectifier is probably bad and needs to be replaced. If TP4 is out of limits, the transformer may need to be replaced! TP4 is an AC voltage that doesn't get converted to DC, and hence doesn't have a bridge rectifier.
Check the Rectifier Board Fuse Clips (HOT fuses!).
The high amp fuses on the rectifier board show this problem the most. These fuses will get hot the quickest, and can generate a lot of heat. Once the fuse clips get hot and discolor, they must be replaced to fix this problem.
First Upgrade: #47 Light Bulbs instead of #44.
Number 47 lamps are a 150 mA (0.945 watt) lamp, where #44's are 250 mA (1.575 watts) lamp. The difference between the two lamps is 100 mA (.63 watts). If there are 75 of these bulbs, having #44's installed is like adding a 50 watt light bulb to the game. The additional power consumption uses more produces more heat and strain on the connectors and plastic game parts.
Rectifier Board Upgrades for AS2518-18 / AS2518-49 and Stern.
John Robertson recommended doing this, and I would agree it is a good idea. Bridges can fail from heat fatique. Installing a heat sink increases the surface area of the bridge, allowing it to cool easier. It really is a good idea as any bridge installed will get hot.
Aluminum transistor heat sinks are available at Radio Shack part #276-1363 or #276-1368. They bolt right to the top of the bridges. The 276-1368 model uses a 4-40 screw (not included). Make sure to buy some heat sink compound (Radio Shack part# 276-1372) too. This aids in the heat transfer from the bridge to the heat sink. It is required! Just spread a thin layer on the top of the bridge before bolting down the heat sink. Get one heat sink per bridge. Note it's a lot easier to install the heat sink BEFORE soldering the bridge in place.
After doing all the previous rectifier board modifications, test your work right on the bench, without installing the power supply back into the game. To do this requires only a power cord, and two alligator clip wires.
Connect the two alligator clip wires to connector J2, pins 6 and 7 on the rectifier board. Then connect the other end of each aligator clip to a 110 volt power cord. When plugging the line cord into the wall, the power supply will be turned on. Then test the rectifier board's "test points" for proper voltages. The voltages may be slightly different than previously dicussed above, since there is no load on the power supply. No load can cause voltages to vary somewhat. Connect the black (negative) lead of a DMM multi-meter to R1's lead closest to the fuses. This is approximately the readings that should be seen:
If the voltages seen are drastically different than the above, check your work. Also check resistors R1 (600 ohms) and R2 (25 ohms).
Test your work with the power supply installed in the game. Just hook up connector J2 (only!), and leave J1 (playfield power) and J3 (logic board power) disconnected. Turn the game on and check the voltages as described above. Having the J1 and J3 connectors removed will isolate the power supply from the rest of the game.
Rectifier Board Fuses.
Rectifier Board Fuse Always Blows.
Fuse F5 - General Illumination (G.I.) Fuse Woes.
First, a good idea is to purchase a clip-on circuit breaker. Instead of replacing the F5 fuse for each test "power on", the circuit breaker can be reset and reused. This is great for G.I. problems and saves lots of money on fuses. Just clip the breaker onto the rectifier board's fuse clips with alligator test leads. A mini circuit breaker can be purchased from any lighting store.
To issolate the G.I. problems:
Each time plug J1/J2/J3 is removed, that part of the G.I. circuit is removed. What ever plugs are left connected are the wiring sections being tested. If the short is in the cabinet wiring, this is easy to fix. Just examine the coin door lamps. If the backbox wiring is the problem, this too is fairly easy to examine. A very common problem here is the ground braid that connects the head to the backbox. This can bunch up and touch one of the lamp sockets on the back side of the insert (display) panel (when the insert panel is closed). Unfortunately the playfield G.I. is the most troublesome section.
Now that the offending section (playfield!) has been isolated, it is time to further isolate which strand of lamps has the problem. There are two G.I. lines in the game- red/white wires, and orange/green wires. Now find a strand (either one), and de-solder one of the lead wires to the strand (thus taking the strand out of circuit). If there is a double wire (double green, orange, red, white) on the strand, be sure to keep the double wire connected together once it's removed from the strand. This lets other strands "downstream" continue to have power. The basic idea is to disconnect a strand, power up, watch the fuse (or breaker), and repeat until you find the offending strand.
It's never easy or quick to find a problem like this, but this is about the only way to systematically find the short without pulling out every bulb or looking at every socket/wire.
The Playfield Solenoids Don't Work.
After getting +43 vdc at TP5, then check connector J1, pin 6 on the power supply regulator board. This brown wire goes directly to the playfield flipper coils. If there is +43 volts at the connector, but not at the brown wire on the flipper coils, there is a problem in the wiring.
Also note +43 volts on some games is used on the early A8 sound board (Lost World to Dolly Parton). A problem on this sound board (or a bad connector there) can cause problems.
If the game is not getting the 7th MPU LED flash, that means +43 volts is missing. After checking all the above, verify there is +43 vdc on the MPU board on the left (connector) side of R113. Now check the right side of R113. If no voltage there, then replace R113 (2k, 1/4 watt) and retest. If still no voltage, there may be battery corrosion damage in this area of the MPU board.
Power Supply AS2518-54 Rectifier Board Upgrades.
The replacement diodes should be a 6A50 (6 amp, 50 volt or higher) diodes (games Eight Ball Deluxe and later were fitted with this size diodes). Higher voltage diodes can be used too, like a 6A2 or 6A200 (6 amp, 200 volt) or even 6A4 (6 amp 400 volts). Radio Shack sells a decent replacement, part number 276-1661. Also, 1N4004 or 1N4007 diodes could be used, but this is not recommended! The amp rating on 1N4004/1N4007 diodes is only 1 amp, compared to the 6 amp diodes that should be used.
2c. Before Turning the Game On: Upgrading the Voltage Regulator/Solenoid Driver Board.
The +5 volt Logic Filter Capacitor.
There is a design problem on the voltage regular and solenoid driver board's ground lines. The ground comes from the power supply to the solenoid driver board, goes through the filter cap and voltage regulator, and then leaves the board through a connector and goes back to the power supply. It then turns around and comes back from the power supply, through the connectors, and back to the solenoid driver board. This puts unnecessary strain on the board's connectors and header pins. It can also give unreliable game play.
For newer (about 1979 and later) Voltage Regulator/Solenoid Driver boards, on the solder side, jump a piece of wire from the negative lead of capacitor C23 (the large filter cap we replaced above), to the trace right below it. This takes the presure off the connectors, stopping pin 10 on J3 on the solenoid board from burning.
On older (pre-1979) Voltage Regulator/Solenoid Driver boards, on the solder side, jump a wire from the negative lead of capacitor C23 (the large filter cap we replaced above) directly to connector J3, pins 18-22 (pins 18 to 22 are all connected together).
NOTE: do NOT do this modification to Baby Pacman's Voltage Regulator/Solenoid Driver boards! Baby Pacman uses a unique version of these boards which is similar, but not exactly the same.
Upgrading the Voltage Regular/Solenoid Driver's +5 volts.
To correct this problem, add a wire from TP1 to TP3. Jump these either on the solder or component side of the board. In the picture above, I jumped them on the component side for clarity. But jumpering on the solder side looks a bit neater. This mod helps saves pins 13 to 25 on J3 on the solenoid board.
NOTE: do NOT do this modification to Baby Pacman's Voltage Regulator/Solenoid Driver boards! Baby Pacman uses a unique version of these boards which is similar, but not exactly the same. Tying TP1 to TP3 will short the unregulated 12 volts to ground.
On the Voltage Regulator/Solenoid Driver board, connector J3 can often be over stressed and burned. In particular, connector J3 pins 10 to 12 (orange wire, +5 volts) and J3 pins 13 to 17 (white wire with a brown trace, ground) are often burned. If any of these pins are even slightly brown, both the header pins and the connector pins should be replaced. Trifurcon replacement pins are highly recommended.
Are Solenoid Driver board AS2518-16 and AS2518-22 Interchangable?
2d. Before Turning the Game On: Upgrading the Ground on the MPU Board.
Newer Games with Foil Covered Cardboard Ground in the Backbox.
To fix this, run a wire (daisy chain) to one metal bracket on each of the backbox circuit boards. Then connect this wire to a metal "real" ground in the cabinet. Also make sure the green solder mask on each circuit board is not insulating a circuit board from the metal mounting bracket.
2e. Before Turning the Game On: Ok, So You Didn't Do the Above. You BETTER do This!
Remove Connector J1 and J3 from the
Power Supply's Regulator Board.
Remove Connector J4 on the MPU Board.
Check the AC Ripple on the Solenoid Driver Board's
Cut the MPU's Battery off the Board!
2f. Before Turning the Game On: Connectors.
Molex makes a crimp-on .156" size female terminal pin called a "trifurcon" pin (not available in the .100" pin size). This style .156" pin differs from the "normal" pin; it has three wiper contacts instead of just one. The more contact points means the female pin "hugs" the male header pin with greater surface area. These are highly recommended. The specs for these pins can be viewed at http://www.molex.com/product/pcb/6838.html. Compares these to the "normal" connector pin specs at http://www.molex.com/product/pcb/2478.html.
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 (sharp scissors do work pretty good for cutting them though). If a good job cutting them is not done, the pins will not insert into their plastic housing correctly. Also always get the tin plated version, NOT the gold plated pins.
Board Mounted Header Pins.
What Connectors Pins are Needed?
2g. Before Turning the Game On: Setting Free Play.
There is another solution though without having to put quarters in the game. This procedure outlines how to make the start button also work as a credit button too. When the start button is pressed, it automatically adds a credit, then starts the game (thus removing the just added credit). To do this double up the credit leaf switch with another leaf switch, which will add the credits.
Now when the start button is pressed, a credit will first be added, and then the game will start and remove the just-added credit. This works especially great if there is no battery installed (hence unused credits are lost when the game is powered off). Otherwise additional unused credits will pile up from matches and replays, until the maximum credit limit is reached. If this is a problem, the match and replay can be disabled options via the dip switches.
* Go to the Bally Repair Guide Part 2
* Go to the Bally Repair Guide Part 3