How to change the mainboard (BCN3D Sigmax)

f you need to change the mainboard on your BCN3D Sigmax, you can order it contacting your reseller or the BCN3D sales team at

For the launch of the BCN3D Epsilon, BCN3D has redesigned and improved the mainboard. This version is fully compatible with previous models and has the same SKU: 10909

To change your mainboard follow these steps:

Download the filament from the two heads (Options -> Filament -> Unload).

If the fuse on your mainboard has blown you may not be able to unload the filament due to the hotend not preheating. You can either go through this procedure without unloading the filament, or try to manually unload it following the steps explained in this article:

How to unload the filament (BCN3D Sigmax)

Move up the printing platform to the top (Options -> Maintenance-> Move Z axis).

If the fuse on your mainboard has blown you may not be able to move the Z axis.  You can manually raise the printing platform by spinning the Z motor spindle bar.


Remove the lower bowden tube from the extruder motor by pressing the grey coupling and pulling from the bowden.

Once the bowden is out, remove the central cover to have access to the mainboard.

Disconnect all the cables, remove the 4 nuts and the three nylon washers that hold the board in place.


To loosen the flat cables you can use a flat screwdriver to carefully apply pressure to the clip. In order to avoid damaging the mainboard, make sure that you apply pressure to the connection clip and not the PCB.


Install the new mainboard and connect all the cables.


Pay attention to the polarity and the position of all cables. If you want to learn more, check this article:

How to check flat cable connections (BCN3D Sigmax)

Place the nylon washers and the nuts to hold the board in place.

The front/right screw does not need a washer.