Printer does not turn on or keeps turning off

Updated 1 month ago ​by Tomáš Chvalina

If your printer doesn't turn on, or it keeps turning off during preheating, the most common causes are either wrong voltage on the PSU or a blown fuse.

The printer does not turn on 

If your printer does not turn on at all, then there might be a more serious problem present. Try the following steps:

  1. Turn the printer off and disconnect the power cord.
  2. Check all the wiring for broken cables. In some cases, overtightening the zip-ties can damage the wire insulation and cause a short.
  3. Check the wiring of your RAMBo board. Make sure that the PSU cables are properly plugged. 
  4. Check if the miniRAMBO fuses are not blown.
  5. Check the PSU fuse. 
    1. Find the PSU fuse, which is located just above the PSU's power plug. 
    2. Remove the cover of the PSU fuse, the best tool for that is the screwdriver that comes bundled with our printer.
    3. Inspect if the wire inside of the fuse is intact. If it is damaged, then it must be replaced (fuses can be found at any local car parts or hardware store. The silver PSU unit uses T5AL250V 20mm fuse, whereas the black Delta PSUZ unit uses a F8AH250V 20mm fuse). When you are replacing the fuse, make sure that the printer is turned off and disconnected from the power source.

MK2S / MK2.5 / MK2.5S

If your printer happens to power off during the initial preheating process, there's usually no serious damage. Most likely you just have the voltage switch set to 220V a 110V power environment. 

  1. Turn the printer off and remove it from the power source.
  2. Find the AC voltage switch for 110v or 220v on the PSU.
  3. Make sure that the rocker is switched to your local voltage setting.
  4. Try to turn the printer on again. 


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


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