The Original Prusa i3 MK3 is the successor of the award-winning Original Prusa i3 MK2 3D printer.

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Critical power failure! Prusa i3Mk3 assembled, but will not start


I recently received my Prusa i3Mk3 and assembled it over the course of several days. I followed the instructions diligently, often triple-checking steps and wire connections and the wire plug-in orientations (the point is, I was diligent and I am confident that I have not caused physical damage during the assembly process, or mis-assembled it)

However, when I switched the printer on for the first time, it initially turned on and I began to start the calibration process (it didn't automatically start this , as I was expecting, based upon the youtube clip, so I was working through the menu system when the subsequent critical failure happened...). But before the initial calibration started, the LCD flickered off unexpectedly. I gave it a few seconds (thinking this might have been part of a self-test process) and then I re-checked the power connection and turned the PSU switch off and on several times, each time to no visible effect.

Several seconds after trying this (about 30-60 seconds later, it was a significant lag) the LCD panel switched on and off several times in quick succession. It looked like it was being switched off and on (or suffering from interrupted power input), but as it said, this happened a significant period after I had tried to reset it using the PSU switch (and in any case, I was slower and methodical when I tried the series of resets).

Now, the after this, the printer will not switch on at all.

I suspect that the PSU has blown, but have no way to verify this.

(For wider context, I am located in Australia (240V) and have used a power point adapter plug to connect the European power plug from the printer to an extension cord... I've owned several European electrical appliances, and never had this issue before).

Question: What is wrong with my printer?

- How do I fix this?

- Who can I contact in Australia for deeper level support?

- Is this a common problem experienced by others?

- What is the status of this issue with respect to warranty?

- Can I get replacement parts get sent out (and what parts; and how long)?

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Turns out the PSU was faulty. It must have blown shortly after the initial build was complete.

I'm not sure what caused it, but the replacement did not replicate any similar issues (thats good), so I can only assume it was a fault within that specific unit which developed after both QC at PRUSA and the initial assembly by myself.

PRUSA very kindly (and quickly, ...considering the shipping time over such a long distance) sent out a replacement PSU. I experienced Very Good customer support!

The subsequent replacement worked fine and there have not been any further power-related issues with this build.

Thanks again PRUSA for the support and responsiveness.


Hi Nate,

glad to hear the second PSU works, you are welcome and enjoy your printer! :)


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Chosen Solution

Hi Nate,

please contact our 24/7 support for further instructions. We are testing all parts before the shipping, so it might be just some loose connection.

Live chat support:

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Nate will be eternally grateful.
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