I'm working on a project that involves stepper motors, and I'm mainly using DRV8825 stepper drivers. At the moment, it seems like only one of my drivers actually gives the motors any current. The others usually return 0s when I measure their VREFs. One returns a value but still can't pull the motors. After checking all of my DRV8825s and finding only two returned VREFs, I checked my A4988s and none of them gave anything (aside from power supply voltage when measuring different pins). Is there a way I can figure out whether my stepper drivers are actually fried? I have a suspicion that maybe the potentiometers on the drivers are thrown off or there's some other issue I can't place. I'm happy to give more information if that can help to figure out what's going on here. Thank you!
Make sure You know which cables goes to the same coil. A DVM measuring resistance will tell that. Connect the two pairs correctly to the driver. Activate the enable and apply power to the driver.
When You try to turn the stepper without power You will feel some hacking but quite easy to turn the stepper.
When power is applied You will most likely not be able to turn the stepper even if stepper current is low.
Use your multimeter to check continuity of motor wiring and connections.
Stepper drivers can instantly be destroyed by loose/intermittent motor wiring, or by attempting to disconnect the motor with the power on.
So, solder all connections to the motor driver board, or use secure screw terminals if provided, and make sure that nothing can move when the power is applied.