One Extruder Stepper motor working the other not

[Kimbleos]

M201. Primary extruder stepper motor does all of the filament supply. 2nd extruder motor does nothing during a print irregardless of mix %. Works manually ok. Voltage to both was initially .54v but now have upped both to 1.1v. Have checked cable and no continuity problems there. When setting the voltage on the problem motor, found that very little movement of adjustment screw either yielde 0 volts or extremely high voltage. Had to finess it to get it on 1.1v. Could this be a firmware problem or that circuit board with the voltage adjustment on it. Also, the fan doesn't run on the problem extruder either.

[Mark]

Maybe the driver is defective, you can swap it with the other axis, see if the driver board is dead or not.
And the fan, how about plug it into another fan connector, will it work?

[Kimbleos]

I have verified that my wires are good, that both extruder stepper motors are good. The problem seems to be in the control board, I believe it is called A4988 in the building instructions. It is the small board that is mounted on the main board upon which the heat sink was placed. I moved that board from extruder 2 stepper to extruder 1 stepper and the problem followed over to extruder 1 stepper. I put it on another stepper motor and the problem followed to that axis. Where can I get a replacement control board as I am now convinced that is where my problem lies?

[Mark]

check one more thing, the voltage of the 4988 board might nor proper, check out this link to adjust it see if it works:
http://www.geeetech.com/forum/viewtopic ... 19&t=17097

[snowman]

I believe you have proven the 4988 board defective. I would suggest that depending on age, Geeetech should replace it under warranty, however, if you are wanting to do something with it in a hurry, Amazon is your friend, just check shipping options so you know if you will have it in 2 days, 2 weeks, or 2 months. All 4988 boards are the same, so it really doesn't matter where you get it from.