Z axis motors underpowered?

[Zorce]

My Z axis motors work when not connected to the threaded rods but once they are connected they dont move. They just seem to hum.
I have the jumpers plugged in per instructions. Are they just underpowered? Any fix for this?
Video example below.
Thanks

https://www.youtube.com/watch?v=q-CHp0JtwuE

[zhangxueyou]

Sorry, your video is private, I can't see it.

[Zorce]

Sorry, I fixed it. Should be good now.

[zhangxueyou]

Can you manually rotate the couplings above z motors?

[Zorce]

If I loosen them yes but they are tight on there. I can take motors lose and the motors work fine. If I unplug 1 motor, the other one will turn the rod with no problem. It is a power issue. Should I up the power pot on the stepper board? Have you seen this issue before? I see other issues like it online but no solution yet.

[zhangxueyou]

Please rotate the screw on Z motor driver until the voltage between the screw and GND is 1V.

[Zorce]

That seemed to have fixed the issue.
Thanks for the help.

[Edvash]

Hi there, i have the same problem
could you please explain to me what do you mean by that fix?
where do i measure the Voltage?
thanks

[zhangxueyou]

Hi there, i have the same problem
could you please explain to me what do you mean by that fix?
where do i measure the Voltage?
thanks

You can see there is a screw on A4988, rotate it.
Use a multimeter to test the voltage between that screw and ground.

[Edvash]

I have tried that, the screw is very jumpy, i can't fix it on 1V
it jumps from 0.3V to around 4.5V in the slightest turn of the screw.