The Original Prusa MK4/S and MK3.9/S are equipped with a 24V xBuddy mainboard. This 32-bit logic board has three removable automotive fuses protecting the crucial components. If your printer or some of its components suddenly stopped working, it is recommended to check these fuses and replace them if necessary.
Before checking the fuses, turn the printer off and disconnect the power cord.
Open the xBuddyBox-cover and the el-box-cover by opening the screws indicated below. Then pull out the fuses and inspect them.
The MK4 PSU uses an F8AH250V 20mm fuse (fast). You can check the pictures below for how to find the fuse in your PSU.
When you are replacing the fuse, make sure that the printer is turned off and disconnected from the power source.
If you find out that any of the fuses are blown, you can easily replace them. The fuses can be found at any local car parts/hardware store or ordered online. It's a good practice to bring the blown fuse with you so that you can get the exact same one.
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And if that doesn't do the trick, you can send an inquiry to [email protected] or through the button below.