How to check and change the mainboard's fuse (Sigma Series)








Allen Key 2.5mm
Flat Head screwdriver


Our mainboards have a removable fuse (0451012.MRL) that protects the mainboard from short circuits. Usually, if your printer doesn't heat both hotends, the bed, and the motors do not function, you will need to change the fuse. To check and change the fuse, follow the steps below:


1. Turn off and disconnect the printer.

turn-off-d25 unplug-turn-off-d25


2. Remove the extruder motors cover in the back of the printer by loosening the two thumbscrews.

extruder-cover-d25 Cropped

3. Remove the lower bowdens from the FRS.

extruder-motor-d25 Cropped

4. To get access to the bottom cover you will need to raise up the printer surface, if you can't turn on the printer, you will need to manually raise the printing platform by spinning the Z motor lead screw.

manually-move-lead-screw-d25 Cropped

5. Remove the inner cover. Follow this guide to understand this process:

How to remove the inner cover

sigma-d25-inner-cover-016. The mainboard's fuse is located on the top left side of the mainboard. To remove it, pull out the fuse by levering it 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


7. Remember to check the flat cable connections before turning on the printer to prevent short circuits. For more information on this, click on the following article:

How to check flat cable connections (Sigma Series)



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
fuse-bcn3d Mainboad's fuse SKU 10222 



replace mainboard eng check flat cable eng


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