Blown Fuse (miniRAMBO)

Updated 1 month ago ​by Martin Lexa

The miniRAMBo board has three built-in fuses to protect the board. If your printer or its parts suddenly stopped working, it is recommended to check for blown fuses and replace them if necessary.

Checking the miniRAMBo fuses 

  1. Turn the printer off and disconnect the power cord.
  2. Open the miniRAMBo cover by removing the screw holding the Rambo-cover doors closed. Please refer to STEP 21 of the assembly manual for more details. 
  3. Now you have access to the miniRAMBo. Pull the fuses out and inspect them. The image below shows the difference between a good and a blown fuse.

Each fuse protects a different part of the miniRAMBO board.

  • F1 (5A fuse) - Extruder motor, X-axis motor, Y-axis motor, and both Z-axis motors 
  • F2 (5A fuse) - Thermistors for Hotend & Heatbed, Print fan & Hotend fan, LCD, hotend heater
  • F3 (15A fuse) - Bed heating
If you own a multimeter, you can check the components for a potential short. This article will show you how.

Replacing blown fuses

If you find out that any of the fuses are blown, you can easily replace them by following these instructions.

  1. Turn the printer off, disconnect the power and remove the blown fuse(s). 
  2. Get a new 5A/15A fuse (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.
  3. Place the new fuse in the correct slot - Double check that you are replacing 5A for 5A or 15A for 15A. 
  4. Unplug any components connected to the previously blown fuse and try to turn on your printer. Check for any kind of unwanted behavior.
  5. Once again, turn off the printer and remove the power cord. Then reconnect all the disconnected components to the miniRAMBO board.
If you have discovered a short-circuited part or if the printer simply still does not work, please contact info@prusa3d.com and we will help you out. 


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Find out more troubleshooting tips here: Community Forum | Assembly Manuals | Youtube channel | info@prusa3d.com


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