Facing problem with a potentiometer in a4988 stepper motor driver when using with NEMA 17

Am using a4988 arduino shield to drive stepper motors , with 12V supply , I have set VRef to 1.6V and i started running it , the problem am facing with trimmer potentiometer which is mounted on driver pcb .When i touch or press the potentiometer with any screw driver or conducting material then only the motor starts rotating .I thought there is problem with driver IC then i changed other board still facing the same .I used total 5 IC’s , facing same problem with all five driver pcb’s.

Anyone please help me regarding this.


It sounds like the problem might be a connection issue; have you tried testing the driver boards separately from your Arduino shield? Could you post some pictures of your setup that show all of your connections? Also, could you post close-up pictures of both sides of your A4988 driver boards?

Also, 1.6V seems way too high for a VREF voltage on our A4988 carrier; what stepper motor are you using and what are you trying to set the current limit to?