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!