Geeetech

I order
5pcs Pololu DRV8825 with 5 heat sink for RAMPS1.4 Sanguinololu Teensylu
4pcs is working properly.
One piece can rotate, but changing direction is not working.

Need replacement.

dear friend：
first，you shou make sure that they are tested in the same environment（the same mother board，the same position x or y or z axis，the same motor）
then，Check the DIR signal OF the drv8825 when the motor is Positive inversion with Oscilloscope。the signal is A straight line or Square wave

4 out of 5 is working OK. swapped the failed one to the working one at the same position result in fail to change the direction: you shipped a non working drive. need a replacement

when you test the module，do you operate with Wrist strap or gloves。i think that the drv8825 don't work due to static electricity on human body. i suggest you buy a new drv8825 chip replace the bad one

Very careful to not haveing static charge by holding the edge of the pcb with gound strap.
Defective product shipped from Geeetech!!

All of Geeetech products have undergone first rigorous testing and second sampling inspection by professional inspectors.
It is almost impossible for us to ship you a defect driver. But it may be caused during transportation.As you know international transportation is hard to control, the package may not be treated friendly or handled improperly on its way to you. And the static electricity may cause short circuit,which is deadly for the chip.
I suggest you to contact the seller for further solution.