Original Prusa i3 MK2S is a successor to Original Prusa i3 MK2 with small hardware tweaks for easier assembly and improved reliability.

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selfest possibly blew the fuse

Hello all

After my initial assembly of a new MK2S kit I did a firmware update (Used 1_75mm_MK2-RAMPo13a-E3Dv6full.hex) which worked according to the firmware-update tool. Then I went ahead and tried the selftest as per the pre-flight video on YouTube.

The first two stages went ok (both fans worked). However, when the printer started the test on the hotend it lost all power and cannot seem to be powered on again (I tried switching off the power-supply and unplugging it too before trying again).

I think it may have blown a fuse but I would like to make sure first if I am right, which fuse I would have to change if applicable and if I can do anything to prevent that from happening again.

Thanks in advance for any help!



Answered! View the answer I have this problem too

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Hi Roger,

your assumption seems to be correct. Please write to our support (info@prusa3d.com).

Please attach a link to this discussion, it will speed up the process.

Have a nice day


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I seem to have a similar issue, and having access to the same information as Roger would be very helpful. I was able to identify the fuse that is blowing, but not why it blows. If you could post more advice on fuses in general that would be helpful.


Hello Isabella

I had mistakenly swapped the power sockets of the heatbed and the nozzle. Due to the nozzle's higher energy requirements the printer blew the fuse every time it started to heat the nozzle. Maybe your problem is the same.




Hi Isabella, please double check all electronics are plugged correctly, it seems to be the issue as Roger described (swapped Extruder and Heatbed)


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Hi Jakub,

Thanks for your quick answer. I will ask for a replacement once I am home and then try this:


It may help me to find out whether I damaged the cables or not.

Again thank you for your help.


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Roger will be eternally grateful.
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