Pololu md07a 18v15 Motor Driver Not working


I am just starting on touching electronics and I have two Pololu md07a 18v15 Motor Drivers.But both of them seem not working properly. I checked I have all the wires and input powers, PWM signals setup correctly. And both Fault Flag Pins are low when the driver is connecting.

Here are the problems:
the first one gives zero output on OUTA and OUTB.

the second one has everything working but the DIR input. The direction goes one way no matter the DIR input is high or low (always OUTA = 0V and OUTB = 1.8 V)

Can anyone care to help me out a little bit and give me a clue of what might be going on here?
Thanks a lot.


Hi, Charlie.

I am sorry you are having trouble with your motor drivers. Could you tell me more about your setup? What are you using to supply power and what motors you are using? Could you post some pictures of your setup?

- Zeeshan


Thanks for the reply. I am using a DC 24V to power the driver, would you say that is the problem and will it damage the driver?

That might be causing a problem. However, I need more information to better understand the situation. Could you be more specific about what power supply you are using? Could you also answer the other questions I previously asked?

- Zeeshan

Thanks for your reply. I’ve attached a picture of my setup.

The motor and the arduino board works fine and the power source is providing 24V power. The first time I connected to the driver, I did see the motor move in a short period. But it never moved as what the arduino code told it to do.

Here are some situation I have run into with different md07a 18v15 drivers I had in hand(they are the same model):

  1. there is no output to the motor no mater what the control signals are

  2. the PWM input can control the speed of the motor (PWM input of 10 to 30 out of 255 duty cycle), but the DIR input has no effects in controlling the direction (the motor just going in the same direction). The next time I tried, the driver behaved like in 1.

  3. the other driver I tried, the motor moves when I disconnected the ground and connecting pwm input on the driver (the DIR input still had no influence).

That’s all I had so far. One of my friend has used similar setup but he told me it works fine for him (with exactly the same drivers). And even he come to help, he could not figure out what’s wrong eighter.

So if there are more information you need please let me know. Thanks.

The Problem is Solved.

I figured out the problem which damaged the motor drivers. It was the power supply jump to over 30V which is the limit of the driver the very moment when plugging the power cord. So the solution is to first plug in the power supply cord before hooking the wires to the driver.

Thanks for the help.

I am glad you solved your problem. Thanks for letting us know what the issue was.

- Zeeshan