Anycubic Kobra- extruder motor not spinning

I have an Anycubic Kobra that I have been having extruder motor issues with and have not been able to find a solution for.

The wheel on the extruder motor doesnt spin forward at all, just kind of vibrates. It does spin backward but even then it tends to get stuck, spins forward for a second, then goes back to spinning backward.

I have already replaced both the entire extruder and the wiring and I’m having the same issue, no change at all which leads me to believe it may be a problem with the adapter plate/chip board (not sure what it’s actually called) that the stepper motor connects to maybe?

Image below of the 4 pin connection on the board I’m referring to.

Does anyone know if I can get this board anywhere else? Anycubic already sent me a new motor and wires but like I mentioned above, it didn’t work, and if this is a piece I can buy myself I’d rather do that than go through Anycubic support again and wait.

My first guess would be wires but maybe the motor driver is shot.

Have you tried wiring another stepper to the extruder stepper’s motor driver and the extruder stepper to another stepper driver?

Yeah so I have replaced the entire motor and wires but no dice. I have also tried connecting the X-axis wire to the stepper motor and have successfully been able to move the motor by commanding the x-axis to move using the LCD panel on the printer so I don’t think that either of the 2 motors I have tried were the problem. My current guess is maybe something went wrong with the 4-pin connection on this board in my screenshot above?

I don’t think it’s the mobo either because everything else connected to that little board in the picture is working fine, like the fans, it’s only the motor that doesn’t work. So perhaps that 4 pin connection is shot or something, I don’t really know. And I’ve been trying to find what it’s even called so I can see if I could maybe find a replacement to buy but haven’t been able to find a name for it anywhere.

Is there a cable that runs to the little PCB? I’m guessing the image shows the hot end and there is a cable that connects the board in the image to the main controller board - could that be where your problem is?

I just took a look at the parts page for Kobra but didn’t see a replacement.

Hi adrianco

Welcome to the forum, Glad you found us here.

usually, when a stepper motor “shudders” it’s how I describe the little vibration instead of moving, It’s usually an issue in the phasing of the stepper motor.

If you look at either end of the cable and look at your 4 wires name them 1,2,3,4. Now depin and switch wires 2 and 3 so your wiring will look like 1,3,2,4. This usually eliminates the shudder.