(Topic ID: 249750)

Improved Motor Driver, A-15680, for Doctor Who

By pellew

1 year ago

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  • 37 posts
  • 28 Pinsiders participating
  • Latest reply 16 days ago by pellew
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#1 1 year ago

I had the opportunity to help @darkpinball to develop a new and improved bi-directional motor driver board for his Doctor Who machine. This board is a drop in replacement for the A-15680 (Cirqus Voltaire, Doctor Who and White Water) board and would most likely also work as a replacement for the A-14768 (Party Zone) and A-22013 (Champion Pub).

The improvements versus the original board are:
-Adjustable current limit using a potentiometer, 0 - 4 Ampere
-Adjustable time before the motor is stopped on over current, 0 - 1000 ms
-Adjustable motor speed using PWM, 0 - 100%, which equals 0 - 20 Volt on Dr Who
-Automatic change of direction on over current
-2 on board buttons for manual running the motor up/down (cw/ccw)
-3 auxiliary inputs which can be used for remote control (or other things, this is not fully decided yet)
-MOSFET design, this means that the full input voltage can be sent to the motor for more speed. The old design using BJT:s had a voltage drop between input and output. This also means that less heat is generated in the motor controller. The speed can be lowered using the “SPEED” potentiometer to match the old design if required.

To put this into words that are less technically:
If the pinball machine requests the motor to go in either direction, but the motor is jammed, the board will do as follows:
1. The board will sense the motor current and if it is above the set threshold of the “CURRENT” potentiometer it will start a timer.
2. If the timer expires (the time is set using the “TIME” potentiometer) the board will change the direction of the motor for a fixed time of 200 ms (this time might be changed after more testing).
3. After these 200 ms the board will again change direction to what was requested by the pinball machine.
4. If the motor is still jammed the board will sense the over current, again wait for the timer to expire and then stop the motor permanently.
5. The board will not run the motor until the pinball machine either changes the requested direction or requests a stop and start of the motor again.

At any time when the board is running the motor it is running at the speed set by the “SPEED” potentiometer.

The board is a bit tailored for Doctor Who pinball machines, but I think this would work on many other machines as well using the same software with the behaviour as described above.

The board will be tested on the machines I have available; Doctor Who, Circus Voltaire, White Water and Champion Pub. If the board seems to be working properly it would be possible to ship the boards together with the Smooth Lifter Kit from @darkpinball.
The price of the board has not been set yet, but a best guess would be around $65. If you are interested in one of the boards then put a comment in this thread. I will then try to synchronize this with @darkpinball so that the board gets shipped with the lifter kit.

I also think there might be more machines using the same or a similar board that would be replaceable. If you know any please let me know, thanks!

20190819_171356 (resized).jpg
7 months later
#24 10 months ago

Hi all,

here is some more information about the board and how to set it up.
The attached chart is for further understanding of the board. The blue line is an approximation of the motor current when the elevator is started and has been run for several cycles. The data is not taken from a real machine, it is just for educational purposes. What we are trying to do during setup in [4] is to find the over current level, as indicated by the orange dashed line, and the time window when we masking the motor current, as indicated by the red shaded area.

The motor driver board will be able to run the elevator even if the playfield glass is removed or the coin door is open! The board has no way of knowing if the safety switch or coin door is opened!

This board will not make your gearbox indestructible! When the motor is running there is quite some energy in the form of mechanical mass that is rotating and moving that the board has no way of reducing. If the elevator comes to a sudden stop, this mechanical energy might still break the gearbox. It is not recommended to force the elevator to a sudden stop for testing!

[1] Information about the software and the LEDs on the board:

Current version of the software is 2. This is indicated during boot-up of the board by turning the "FAULT" LED on and then flashing "STATUS" LED two times (as in version 2). Then the "FAULT" LED turns off and the "STATUS" LED turns solid on.
During an over-current fault the "FAULT" LED will turn on and the motor will be driven in the opposite direction for 100 milliseconds (to release the pressure on the gear box) and then stop the motor. The fault will be cleared as soon as the manual or CPU-control is deactivated by releasing all manual buttons or the CPU not requesting the motor to run via J3.

[2] Manual and remote control

Manual control is possible by pressing "UP" or "DOWN" for either CW (clock-wise direction) or CCW (counter clock-wise direction). When either button is pressed the board will indicate this by flashing the "STATUS" LED 5 times per second.

Remote control via connector J3 is possible by holding both buttons ("UP" and "DOWN") pressed during the entire boot-up sequence. Then the motor can be driven in either CW or CCW direction by connecting "IN1" to "GND" or "IN2" to "GND". When either "IN1" or "IN2" is connected to "GND" the board will indicate this by flashing the "STATUS" LED 5 times per second.
When the remote control function is activated the "UP"/"DOWN" buttons AND CPU-control (via J1) are disabled. This is because of safety reasons, I only want one way of running the motor at once.

[3] CPU-control

CPU-control in CCW direction is initiated by the game CPU connecting pin 1 on J1 to ground.
CPU-control in CW direction is initiated by the game CPU connecting both pin 1 and pin 2 on J1 to ground.
When the CPU board in the game requests the motor to run in either CW or CCW direction the board will indicate this by flashing sequences on the "STATUS" LED:
CCW direction is indicated by 2 short flashes followed by a delay
CW direction is indicated by 3 short flashes followed by a delay

[4] Setup
The setup of the board can be done by following these steps. The board can be powered during setup. Use a small flat screw driver to change the potentiometers:
[4.1] Turn the "CURRENT" and "TIME" potentiometers fully in the CW direction.

[4.2] Set the "SPEED" potentiometer to about 12 o'clock.

[4.3] Try running the elevator carefully by pressing "UP" or "DOWN". NOTE! Be very careful here because you haven't setup the "CURRENT" and "TIME" settings yet! If the elevator jams or doesn't move freely, release the button and fix the mechanical problem first!

[4.4] Observe the speed when running the elevator up and down by using the buttons. Adjust the "SPEED" setting until you are happy with the speed. The buttons have to be released when changing the "SPEED" setting. Tests has shown the about 12 o'clock is a good starting point.

[4.5] Next run the motor in either direction by pressing the "UP" or "DOWN" button and keep it pressed. At the same time as the motor is running, slowly adjust the "CURRENT" potentiometer in CCW direction until the motor stops and the "FAULT" LED turns on.

[4.6] Release the buttons and increase the "CURRENT" setting in CW direction slightly.

[4.7] Try running the elevator for several complete cycles in both directions by using the "UP" och "DOWN" buttons. If the motor stops and the "FAULT" LED turns on then go back to step 4.6. When you are done you have setup the over current value as indicated by the dashed orange line in the attached chart.

Info: This step is a bit tricky. We are trying to find the time window when the motor just has started and will draw excessive current. This window is indicated by the red shaded area in the attached chart.
[4.8] Start the motor in either direction by pressing either "UP" or "DOWN" and keep the button pressed for at least 2 seconds and observe if it stops ("FAULT" LED turns on) or continues to run.

[4.9] If the motor continues to run for the full time then turn the "TIME" potentiometer slightly in CCW direction and go back to 4.8. If the motor stops continue to 4.10.

[4.10] Turn the "TIME" potentiometer slightly in CW direction and try the motor for several seconds in both directions. Now the motor should never stop and the "FAULT" LED should always be off. You have now setup the time window as indicated by the red shaded area. During this time the motor current will be ignored.

[4.11] If the motor sometimes stops it might be needed to adjust the "TIME" and/or "CURRENT" setting slightly in the CW direction.

Let me know if something is weird, wrong or to complicated to understand. As an engineer it is sometimes easy to over-complicate things.


Doctor_Who_Motor_Driver (resized).jpgDoctor_Who_Motor_Driver_Chart (resized).png
1 week later
#27 9 months ago

Hi all,

yes, the boards are available and they will be shipped together with Doctor Who Smooth Lifter Kits by darkpinball

Anyone who has signed up in this thread will be contacted by darkpinball when the kit is ready to be shipped.

At the moment the boards are only sold together with the kits because of limited supply. Later on they might be available for separate purchase for other games or if you did not buy one with the kit.


#29 9 months ago

Then we'll sort it out Rdoyle1978
Sent me a PM.

9 months later
#37 16 days ago
Quoted from eyeamred2u:

I would like to see a video or some illustrations to show how you initiate step #3. Are you using a jumper wire across the pin(s) to ground to GROUND?
At what point can you initiate these functions? Attract mode? Coin door open? Does the game have to be in a certain test mode?

Hi, step 1-3 is just information about how the board works. Nothing you need to do.

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