Bench repair of the Gottlieb sys. 80 driverboard.
To test this board completely , all transistors and IC's, we need very little material, two switches two pushbuttons four LED's and their resistors and some edge connectors will do.
The driver board.
As we need some edge connectors for this board I recommernd the edge connectors as used in Video games type Jamma. You can still find these at low price at most electronic supplyers . Cut and glue some of these ,as indicated here below ,to make suitable connectors for the board.
Double sided edge connectors,( step is 3.96). To make a connector of the right size just cut some pieces and glue a small wooden strip at both sides to make one connector out of it.( I used super glue)
Here 4 pieces where glued to make one long connector that fits on J2,J3 and J4, at the same time.
The connectors placed on the board.
On top J1, at the bottom the long connector fitting on J2,J3 and J4. And finally at the left one connector that covers J5and J6.
Indicates wich side is the component side at the connector , this to avoid putting it the wrong way!
What are whe testing ?
What is the meaning of the test mounting? Well we are going to steer all the output driver transistors, those in command of the coils and those in command of the lamps of the pinball machine. Most of these drivers are activated by IC's ( flip/flops), some are directly steered by the CPU board. For the directly steered ones we will apply a small current on their base. For the others it will be the flip/flops that we will place in an "on" or "off" state, the connected transistors have to follow these commands. In all cases we will monitor the outputs using a test-led, again this test-led will give us an "on" or "off" if all is well. To steer the flip/flops we need a "clock-pulse"that will be a simple push-button, furthermore the flip/flop needs a positive or negative tension on its inputs. Depending on the tension present at the inputs the clock pulse will toggle the flip/flop in its "on" or "off state.
Print the schematic .....
How are the connectors wired? Well there are three goups of a number of pins that are wired together, plus the tension . NOTE, as the connectors have two sides , pins are at the component side or are not. To make the difference I call all pins at the component side C pins. Example pin 3 at component side is called C3 , pin 6 at solder side is just Pin 6.
+ 5 volts comes at pin C2. Gound at pin C1.
The first group is made bij pins; ,C5,C6 and C7.
The second group by pins; C3,3,4,5,6,7,8,9,10,11,12,13,14,17,20,21,22,23,24.
The thirt group by pins; 15,16,C20,C21,C22,C23,C24.
The tension and these three groups will be connected to the command box.
The long connector, J2,J3, J4....
At the triple connector, the following pins are connected all together and grounded. You run the wire to ground them to J1. Here the pins that are grounded.
And last thing to do is apply +5 volts at J3 pin 24. Run a wire from that pin to J1 +5 volts.( pin C2)
At connector J5 , pin 3 is grounded
At connector J6 pin 4 is grounded.
To execute the tests and steer all transistors , we need three commands , these are made by a switch and two pushbuttons in the command box.
Some LED's ( 4) and their resistor, two switches, and two pushbuttons, and of course some wire.
The schematic of the command box is that simple..
Look out for the polarity of the LED's , the " flat" side of the LED always connects to the ground side.
This way the command box is made, the dimension of the box is 2x3 inch and about 1,5 inch high. At the left upper corner the on/off switch and the LED indicating the box is " on" In the middle the group 1 switch , who will preset the outputs to "high" or "low" at the same time the LED will light up , the red for high and the green for low. In the lower right corner the test-LED connected at a test rod to touch the output pins and check if the outputs are low or high. The two push buttons are the commands for group 2 and group 3. How to use the command box becomes clear in the users manual below.
In the command box goes the tension +5 ,and out of the box comes +5 and ground, and the three goups, add to that one wire that is connected at the test LED included in the box.
The connection of the different groups created on J1 is finally this ( see drawing)
The command box connected at the edge connectors. Lying in the foreground the test rod, easy to check all outputs no need of a voltmeter.
To test the direct steered transistors, wich are, Q53,Q54,Q55,Q56,Q59 and Q60, just push the pushbutton of group 3. As long as you push there will be output at the transistors.You find the outputs at J8 pin8, J6 pin 3,2 and 1 en at last at J4 pins 7 and 8. A last remark, to test the three 2N6043 transistors Q53, Q59 and Q60 it is needed to jumper the diodes at their input CR1, CR5 and CR6. If the driver board is from a 80A the other three transistor will have diodes at their input to Q54, Q55 and Q56 ( CR 2, CR3, CR4)bjumper these to, If the board comes from a 80B these diodes are not in place and replaced already by jumpers.
The outputs are checked using the test- LED , directly included in the command box. Below here again a short design of the test-LED .
When using the mounting for the first time , try the test-LED out by touching ground with the test-rod, the LED should light up.
To test the outputs of the transistors steered by the flip-flops, put the test rod at the output pin(s) at:
J2 pins 1,2,3,4,5,7,8,9 and 10.
At J3 pins, 1,2,3,5,6,7,8,10,12,13,14,15,17,19,20,21,22. C1,C2,C3,C4,C5,C6,C7,C8,C10,C11,C12,C13,C14,C15,C16,C17,C19,C20,C21,C22,C23,C24.
At J4, pins 1,2,3,4. And at J5 pin 2. All together 53 pins, HOW comes there are only 52 flipflop outputs? Well one output Q4 goes at two pins at J2 pin 1 and at J3 pin 1 at the same time.
Two possibility's , the test LED will go "on" or not , to change the status of the output , change switch of group1 , and push button of group 2. Every time you do that the outputs will change from on to off. As all the outputs change at the same time you can check first all the outputs for one position then all for the next. If in one of these positions the output does not change the transistor is bad, if the 4 transistors of the same flipflop do not react then the flipflop is bad. To make things easy are the two LED's ( red and green) connected at the switch of group 1. When the red LED is "on" and you push the button ( group2) the outputs will go hight, if the green LED is "on" and you push the button the outputs will be low. Never forget to push the group 2 button afther you change the switch otherwise the outputs will not change.
Attention there are 4 outputs that will work inverse of the others that are Q49, Q50, Q51 and Q52 , at pins 12,14, 19 and 21 of J3.
Outputs of the " big" drivers 2N3055.
To test these just push the button of group 1. Normally the output gives a "high" test-LED is "on" it will ( and has) to go out when you push the button.The three ouputs are to find at J4 pins 6,12 and 13. If one of these does not work it still can be the driver transistor ( MPS-U45) in front of the 2N3055 that is bad. So measure both transistors.
We still have to check the 4 outputs of this IC. Push the button of group 1, the output pins at J5, 1,5,6 and 7 will change from high to low. If not the IC is bad.
Quick measuring method.
To avoid counting the pins where to find the outputs , just measure the outputs directly at the transistors! You can measure every transistor output at his metal tab sticking out, and the smal ones at the right pin. All of these easely to touch.
Using the command box ,once the connectors are pleced on the board and with the quick measuring method , it takes only 3 minutes to have a dynamic test of all the transistors . I think it is worthwile to have this small instrument at hand! Succes .