RAMPS 1.4 Low Voltage to Steppers??!!

Afternoon Guys, having a bit of a problem with the ramps setup and was hoping someone could point me in the right direction.

The current set up I have is a RAMPS 1.4 board with an arduino 2560 board using 5 stepper drivers A4988 all running from a 12V 500W ATX power supply. I have fully connected the board with end stops/extruders/heated bed etc.

For steppers I am using a wantai motor 42BYGHW609 (nema 17) (average voltage 3.4V, average current 1.7A)

All is connected and working fine apart from the steppers (heaters, end stops etc). All I am getting from the stepper is a high pitched squeak and juddering movement backward and forward a few mm. Through looking on the internet I am thinking the steppers are not getting enough voltage, so I have adjusted the voltage of the potentiometers on the stepper drivers to their max and I am only getting 0.14V. According to the internet I should be getting between 3.6V-4.5V range from the stepper drivers. I am measuring between the center of the pot and the ground pin.

I have tried different firmware (sprinter and marlin) and still getting the same readings from all of the stepper drivers.

Has anyone got any ideas?

I think you mean 0.36 to 0.45 which would be correct? With 0.14v its not surprising the motors won't co-operate!
Your motors are good - I have used the same ones for a long time.
Did you measure the voltage between the power connector ground and the pot rather than the pololu ground pin and pot?
I'm wondering if you have a poor ground connection somewhere.

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Waitaki 3D Printer

Hmmmm, when you say "juddering movement backward and forward a few mm." makes me remember the same issue I had when I first started playing around with RAMPS. You do have the mini jumpers on right?

Romel