Help: Left Hotend Fan? Wiring error  

Active Member

I've just assembled my MK3S and after running the self test, it failed immediately with the following message:


After browsing the forums, I've tried:

1) switching the extruder fan and the print fan. The extruder test passed, then failed on the print fan. So that would rule out a board issue.

2) I did a wire continuity test with a multimeter. All three wires seemed to pass the test.

3) I've double checked all the connectors for looses wires and they all appear to be solid.

The last test I would like to perform, is actually plugging the fan directly into a power source to see if it works, but I'm not sure how to go about doing this. I do not have any 5v 0.25W 0.05A plugs to test it with (I do have a universal AC/DC power adapter with I can switch to 5v, but trying that did not work. I tried it on both fans and it didn't power either.

There's a knowledge base article witch says:

" can unplug it from the electronics board and test it with the 12V DC (MK2/S) or 5V DC (MK3) power source."

Is this saying I can somehow test the fan directly with the power source? Anyone have any instructions on how I might be able to test the fan? Any help would greatly be appreciated.


Posted : 17/05/2020 7:57 pm
Active Member

UPDATE: With the help of support, we were able to determine that the fan is dead. They suggested hooking the fan up to a 9volt battery to see if it works. Pure genius! Extruder fan was dead, the print fan was fine. They are sending a new fan.

Thanks Prusa Support!


Posted : 17/05/2020 9:19 pm

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