Leon Borre Bally 6803 repair
6803 Control Module.
CPU Bally Midway, 6803 based
Thanks to Ed Burton who did some corrections after translating.
This board was created when Bally and Midway where working together and can be found in this machines; Cybernaut, Eight Ball Champ, Beat the clock, Hot Shotz, Lady Luck, Motordome, Black Belt, Strange Science, City Slicker, Hard Body, Special Forces, Party Animal, Heavy Metal Meltdown, Dungeons & Dragons , Escape from the lost world, Black water. Here Williams bought Bally, and two more games came out with this board,Williams games, Truck Stop and Atlantis.
Some of these pinballs have different displays, different soundboards. Refer to the game list here to find out which style was in which different machine.
On the 6803 board is not only all typical CPU circuitry, like game roms, memory, selections , but also the whole driver section , to drive the programmed lamps and all of the solenoids. It is a driver and cpu board in one. Further more the 6803 cpu has two input / output ports of his own, that way the extra output ports , generally PIA's ( 6821) on this board are limited , only two more. As the 6803 has like his brothers ( 6800,6802 ) only 40 pins , to realise the extra in-output ports they did multiplex the first 7 addres lines and the data lines. And at last, at start up reset , you have to choose the working mode , with or without internal memory.. All of this makes the cpu and the board more complicated then other Bally boards. Nevertheless Bally did hold on to the "on board" led to give us a clue of the possible failures at power up. The led will flash a few times. The number of flashes is sadly not the same at each machine.
The purpose of this test program is to repair the board out of the pinball on the bench, and at the same time and with the same test eprom to test all of the outputs of the included driver section. As usual we will start by testing the special output ports of the 6803 and the connected PIA's , followed by a memory test , and returning to the controlling of the outputs to lamps and coils directly to the output connector pins of the board , this is a way of testing all circuitry in between the IC output ports and the connector. The lamps and coils are replaced by a series of leds plugged directly onto the connector.
The 6803 control board, normally a battery is at the top in the right corner .
The schematic.... 
Connecting the board.
There are two possiblities to connect the board, you need to run the test program only, or you need to run the board on the bench with the game roms.
We start with the connections to run the test program . What we need is a 5 and 12 volts supply. Use an old PC power supply. Because some 0 volt returns on the board are separated ( the return for the lamps and the coils ) we bring these returns all together to logical ground. Here a drawing how things are connected. The transfo ( in red) 2x12volts AC is not needed to run the test , it is only needed to run the board with the game roms. On the board are some jumpers. Use these settings to run the test program ; W2, W4, W6 = in and W1, W3, W5 = out. These are the settings to use 27128 type eproms in U2 and U3. About all the games have 27128 eproms as game roms, so, most likely you must not change any jumper setting.
J1 receives 5 volts on pins 10-12, Ground on pins 7-9, and 12 volts on pin 6. And pin 5 and 6 of J14 are also connected to 0 volt. The red tiny transformer delivering 2x 12volts AC has it's middle tap at 0 volt both 12volt tensions at pin 3 and 4, the 2x 12 AC volts is only needed if you run the game roms in the board.
A connector at J1 on wich the leads to 5 and 12 arrives. The blue and black plugs are to connect a 2x 12 volts AC , used if the board is started up on the bench with the game roms. In the left upper corner connector J14 pins5 and 6 are grounded.( 0 volts).
The tiny 2x12 volt transfo i use.
The test eprom download here .. burn it in a 27128 and place in socket U3.
Update: A modified version of the test ROM file can be downloaded here .. . This version slows the solenoid test speed to about half of original. Otherwise, it is identical to Leon's test ROM. Thanks to Scott Charles for this revision.
Do not use the test eprom when the board is still in the machine. You can ,but remove all connectors except J1. Otherwise at a certain moment to much solenoids at once would be activated.
Start.
Is the test eprom plugged in at U3 ? The moment the tensions are applyed the on board led will blink rapidly. The led is connected directly at an output of the CPU chip ( pin10) only one transistor is between the led and the output. In case the led does not blink first control if there is a signal at Pin 10 ( U1), this to cover the rare case the transistior or the led itself is bad. If the led blinks we control the outputs of the CPU ports at pins 10 to 20 pin 8. On the PIA's ( U7 and U8) that are pins 2 to 17 19.
The test does not start up.
When the test does not start up, remove the test eprom and , if present , the game rom at U2. The 6803 does not need many signals to start up. Check first pins 4,5 and 6 you find 5 volts Only pin 6 can be a problem, the reset signal coming here originates from the 12 volts ; thrue transistor Q2 and Q3 the condenser C1 of 8uF is charged, when charged he will launch Q4 and that way open Q5 bringing 5 at pin 6. As a first check, undo the 12 volts, the reset (pin 6) has to go low to 0 volts, reconnect and it has to go up to 5 volts. If that is not the case check the transistors or replace them. On pins 2 and 3 arrives the clock signal , measure about 1 volt at pin 3, the clock signal is formed by three elements ,the cristal and two condensers, it is extremely rare it will not work. Afther measured the clock signal, put off and on the board again. The clock signal is sensitive and touching the pins when measuring can influence the normal working of the cpu. Now we check the outputs of all pins from 21 to 40 , that are the address signals and the multiplexed address/data signals. Find on all these pins between 2 to 4 volts only pin 39 is an exception with 1 volt. If all signals are missing the 6803 is bad.. If one or some missing at pins 30 to 37 expect that U5 or U6 is bad. If one or some of the others are missing, first bend upward the pin, and check again , is the signal still missing ? The 6803 is bad. If with the pin bended upward the signal come true, you have a short on that line; find the short by eliminating some connected elements, by unsoldering them or by cutting temporally some runs, there is no oher way to find such a fault...
Reseat the test eprom and try again, is there activity with the test eprom in place ( check the address data lines) but the led does not blinks, check the connection to the test eprom , you have to find on his data pins and addres pins signals 2 to 4 volts at pins 1 to 13, 15 to 19 and pin 22, at pins 14 and 20 = 0 volts , at pins 21,23and 24 = 0,5 volts. Only address signals to pins 1 to 8 where not checked as they come from the demultiplexer chip U6. If missing one of these the chip is bad. If missing a data bit at pin 9 to 17 the data demultiplexer chip is bad at U5. Leaves only pin 22 with the select signal ,check U9 and U10 where it comes from.
We can assume you found the fault and the test is running now , the led blinks rapidly.
Check of PIA and CPU outputs.
Now the test is running, we can check both PIA's U7 and U8 Their output pins ( 2 to 17 19 ) will "dance" up and down between 5 and 0 volt. Is there one missing , again bend the pin upwards,and check again. Still mising the PIA is bad, is it ok at the bended pin , then we have a short on that output line. Like at the CPU outputs we need to remove the short by looking for the bad element causing that and connected to that pin. Use the schematic to find the connected elements, ( not that much) and deconnect them one by one , by unsoldering or cutting temporally the run. The outputs of the cpu ports, are at pins 13 to 20 and 8,10,11 and 12.
Is there a PIA that miss ALL output signals, probably the PIA is bad, or one of the select signals is missing . The select signals arrive at pins 21,22,23,24,25,35 and 36 , again signals between 2 and 4 volt. Infact these are again address signals who where already checked, the only reason they are missing at the PIA is a bad contact in the socket or a broken run. Except for pins 23 and 24, these address signals pass by two gates at U10, U11 and U14, use the schematic to see wich gate they do not pass and replace the gate IC.
Now we can assume you have a working board with all basic signals present. Time to go to the second part of the test, memory test and driver elements tests.
Memory test .
The memory test is launched by the push button on the board. When launched the led stops blinking and remains steady for a short while, that can be " on" or "off". Afther a short moment the led starts blinking again in a slow rythm more "on" then " off" , this means we passed the memory test ok, and we are at the driver tests. If the led does not restart blinking there is something wrong at the memory chip, replace the memory chip, before we do we take a look at the signals arriving at the memory chip U4. Again we find mostly all the address and data lines coming in between 2 and 4 volts, Other signals are 0 volt at pin pins 14 and 20, and 0,5 volts at pins 21,23 and 25. The only signal that is new here is the selection signal at pin 18, if missing look at U9 and U10 , two gates where it has to pass. If the signal at the input of the gates is present and missing at one of these outputs , ( use schematic ) replace the chip.
Controlling the switch matrix.
The switch matrix is at connectors, J4 (playfield switch return) , and J3 ( cabinet switch return ) , and J5 . We test the the outputs AND the inputs in output mode. Why , output test is more easy, and it is not possible that complex structures like the PIA or the ouputs of the CPU port would work in output mode and not in input mode...
The switch matrix is tested using the basic test mode, the led is blinking fast,as the connector pins are directly at the pins of the PIA's and at the CPU port. Only a resistor is between these two , as a security if at anytime a pin should be at ground.
Restart the test, and while the led is blinking fast ,measure, using an normal universal voltmeter ;
At J3,pins 4 to 15 the needle wil balance between 1 and two volts. Pin 1=5 volts, pin 2 = 0 volts.
At J4, pins 2 to 15 the needle will balance between 1 and 2 volts. Pin 1 is at 5 volts, if you have jumper W8 in place, pin 1 will balance to, if you have instead jumper W9 in place..
At J5, pins 7 to 15 the needle balance between 1 and 2 volts. Pin 1 2 = 5 volts, pins 3 4 = o volts , pin 6 = nc.
Controlling the display drivers.
The display is connected at J2. Again almost directly to PIA U7. Only pins 9, 10, 11, 12 and 13 passing trought U13 , if missing one here look at that IC or replace it. Again you mesure at all pins ( 2 to 18) 1 to 2 volts , a balancing needle on your voltmeter. Pin 1 is at a constant 5 volts.
Controlling the driver part.
To check the controlled lamps driving part we need some extra material . On the output connectors we will connect a led-strip that will substitute for the lamps and the solenoids.
The principle of the led-strip is as follows, see drawing;
;
Here the led strip, you can connect the red lead to 5 or 12 volts , the connector fits on the heavy coil connector pins.
On the back side there is a connector strip fitting the finer lamp connector pins. We can see also the 470 ohm resistors.
Furthermore we need another smal adapter, we connect a 2200 ohm resistor between ground and pin 19 of U14.
The resistor is fixed at two mini hooks to connect easely to pin19 of U14 and ground .
The board looks like this, ready to check a lamp connector.
The resistor connected between ground and pin 19 of U14, the led-strip on lamp connector J12, using the fine connector strip at the back of the led-strip.
Testing the lamp-output connectors.
The led-strip is connected at J10, J11, J12 and J13, all programmed lamp connectors. every time the driver test is launched ALL leds of the connector will light up on stay "on". Except of course where the connector key is ( no pin) , the result is;
J10 All led go on except 5 ( key) On this connector directly during the basic test 3 leds will blink, 1, 7 and 16
J11 all led's except 5 ( key )
J12 All led's except 5 ( key )
J13 All leds except 9 ( key )
ATTENTION , during basic test NO leds may go "on" ( excepted the four mentioned on J10) If some would go on during basic test that means a thyristor ( 2N5060 ) is bad. On the schematic is easely to find wich pin is connected at wich thyristor.
All thyristors are driven by 3 IC's U15, U16 an d U17.
In case a led will not light up. Remove the led strip and measure with a logic tester if the thyristor receives a command pulse. ( at the middle lead of the thyristor) If that is the case the thyristor is bad. If no command pulse check at the output of the IC's ( U15, U16 or U17) use the schematic to find out wich IC's is commanding wich thyristor ( easy) . If there is no command coming out the IC replace it , if all outputs at that IC are missing the same .. If there is a command , check the resistor between the thyristor and the IC output pin, that is the only thing in between...
Testing solenoid connectors
For the solenoid outputs we place again the led-strip on the solenoid connectors, J6, J7, J8, J9. The results must be ;
J6 : Led 1 and 7 will blink during the basic test, 2, 3, 4 and 5 during driver test . Led 6 never lights .
J7 : Led 3 and 4 will blink during basic test, 1 and 2 during driver test. Led 5, 6, 7 and 8 no output.
J8 : Led 1 and 5 will blink during basic test, 2, 4, 6 and 7 during driver test. Led 3 never .
J9 : Led 9 and 10 blink during basic test, 1, 2, 3, 4, 6, 7, 8 and 11 during driver test. Led 5 never. This with W8 in place , if you have jumper W9 instead led 9 will not blink during basic test.
First the led's who blink during the basis test will blink all TOGETHER, led's that blink during driver test will blink one afther another, giving a " running light effect". During the test that the led should light up , it MUST blink, a steady "on" means the driver transistor is bad. All basic commands come from U14 . When you have a led that will not blink , check first the outputs of that U14 pin 1 to 16, if the command is there, you have a fault between the command and the output connector. There are only two things, the driver IC ( CA3801) or the driver transistor. Follow the command using schematic sheet 5.
Extra control.
For technological reasons, not explained here, is an extra circuit on the board , it start with the 2x12 volt AC signals , so connect first the transfo . This signals will among other functions , generate interrupts . Just look at U12 at pin 6 and 2, You must find a signal of 2 volts. If ever , not likely, you do not have that signal replace U12, use sheet 2 of the schematic to control other elements ( some diodes and resistors.)
Try out with game roms
A last ultimate test you can do , is to start up the board on the bench using the game roms. We need to connect the 2x 12 volts AC transformator,( at pins 3 and 4 common to 0 volts) and place the led strip on one of the lamp connectors. The common of the led strip is to be connected at one of the 12volt AC connections !!! If the board starts up ok, and works fine , these led's should blink as they represents the programmed lights of the machine, who normally blink afther power up. You are completely shure the board is ok now .
The following information was not part of Leon's original site.
Graphical Depiction of Test LED Behavior
The image at right graphically depicts the behavior of each solenoid driver circuit when using Leon's test ROM.
The firing order during solenoid test (after pressing the diagnostic button) is...
- J8/4 and J6/2 simultaneously
- J6/3
- J6/4
- J8/7 and J7/1 simultaneously
- J8/6
- J6/5
- J9/1
- J9/2
- J9/3
- J9/4
- J9/6
- J9/7
- J9/8
- J9/11, J7/2 and J8/2 simultaneously
A video of Leon's test ROM in action on an Eight Ball Champ MPU can be found here