How to check and change the mainboard's fuse (BCN3D Sigmax)


 Allen key 2.5mm
Phillips screwdriver
Flat Head screwdriver


Our latest mainboard model has a removable fuse (0451012.MRL) that protects the mainboard from shortcircuits. Usually, if your printer doesn't heat both hotends and the bed, and the motors are not working wither, you will need to change the fuse. If your mainboard doesn't have the removable fuse, you will need to replace it for the newer model.

To check and change the fuse, follow the next steps:

bcn3d-main-board-1 bcn3d-main-board-2
Old mainboard model New mainboard model


1. Turn off and disconnect the printer.



2. To get access to the central cover you will need to manually raise the printing platform by spinning the Z motor lead screw.


3. Use the Allen key to remove the frontal screws and the Phillips screw to remove the bottom screws in order to extract the central cover.

screw-iconx2 M3 8mm

screw-iconx2 M3.2 9.5mm



4. The mainboard's fuse is located on the left side at the top of the mainboard. To remove it, pull out the fuse by levering with a flat head screwdriver. If the fuse is damaged, replace it. The fuse doesn't have polarity, you can install it in any direction. 


mainboard-fuse-bcn3d-2 mainboard-fuse-bcn3d-1


5. Remember to check the flat cable connections before turning on the printer to prevent shortcircuits. Visit this article to get more information about this:

How to check flat cable connections (BCN3D Sigmax)



If replacing the fuse doesn't fix your issue, please get in contact with the support team by filling this form: Support form.

Forum community 

Repair didn’t go as planned? Check out our forum community for troubleshooting help.


It's important to keep your printer in good shape to make the most out of it. In this chart, you can find a list of the extruder maintenance procedures and how frequently these should be done. Maintenance Plan


bcn3d-recycle  Take your e-waste to a certified recycler. Check how we do it in BCN3D.


Parts   Buy these parts
Mainboad's fuse  SKU 10222


check flat cable eng


replace mainboard eng


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