Adjusting Voltage on A4988 Stepper drivers

Hi
Some of my motors are not moving, just making a noise. I suspect that the voltage is too low. When I turn the Turnpot on the stepper drivers ( Ramps 1.4 ) it seems that there is no beginning or end to the Turnpots. The help says turn left reduces the voltage & turn right increases, however the pots don't seems to have a beginning. Just keeps turn ?? Is this correct ?

Thanks

Thats right.
You can start adjusting them without power on by setting the centerpoint of the potmeter (50%)
Look closely to the potmeter, they have three legs. Two on one side, one on the opposite.
The turning part has a flat side.
Now turn the potmeter until the flat side is parallel to the two legs side.
This is the centerpoint.
Now turn the potmeter 30°- 45° to the left and you are in the ballpark.

Next step is to power on the ramps and measure the voltage between GND and the third leg ( or at the probe, if the heatsink doesn´t cover it )
It should be between 0.35 and 0.55 V ( or whatever the manual says)
Caution, some A4988 use shunt resistors with different values.
[R100] is standard.

Good luck
-Olaf

Hi Olaf,

Thank you for your reply, I will try that tonight when I get home. I was worried that there was something wrong with the Pods as they just kept turning without an end to the turn. Hopefully my Motors will move now and not just make a noise.

Thanks again.