I am using a sparkfun redboard and I have been working with two different TB6612 drivers. I connected the first one to the NEMA-17 motor like in this tutorial: https://learn.adafruit.com/adafruit-tb6 … per-motors. It worked once and then stopped working. Using a multimeter, I was unable to find any voltage going to the motor coils. I tried another stepper motor I need to drive with this driver, https://www.robotshop.com/en/rbsoy03-so … gKyIfD_BwE. I also checked the wiring several times and changed usb cables to troubleshoot. None of those changes fixed the problem. I’m using 8 D cell batteries with this converter: http://www.mcmelectronics.com/product/82-14825. I eventually soldered another driver and it started working again. However, after several uses, it has stopped working. Can someone please help me figure out why this problem keeps occurring? Thank you.