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Bed not heating, middle positive PSU connector burned  

New Member
Bed not heating, middle positive PSU connector burned

Hello all,

my print on my i3 mk3s failed today with an error M112 and any new prints I tried failed with the same error. Upon further inspection it seems the bed is no longer heating at all. I started disassembling the printer and noticed the middle positive power connector on the Einsy board was slightly burned (see picture).

All other connectors, including the ones on the PSU and on the bed and the fuses seem fine although I have not completely removed the board from the printer so I might not see everything.

Has anyone experienced something like this? How do I best go about troubleshooting/fixing this? Do I need a new bed, board or PSU?



Edit: The red LED on the bed was also not lighting up when I tried to heat it after the error so I believe the bed is definitely busted. However I would like some feedback here before I buy anything new that I might not need or might break again.

This topic was modified 1 year ago by tobiderfisch
Posted : 16/12/2022 3:49 pm
Illustrious Member

Thats caused by a loose connection, it causes increased resistance and heating.  It would be pretty hard to damage the bed itself and if you had it would be noticeable as its basically uses resistive heating.  You would be looking for broken tracks which would be obvious.  The heating grid are tracks on a big pcb (the bed) that is covered in a non conducting lacquer.  The led on the bed goes between the inputs, if its not lighting then that would suggest no power is getting from the einsy to the bed.  Id check your wire continuity and the pictured damaged connector should be replaced with the same rated crimp put on PROPERLY regardless.

It is possible that the heat has damaged something on the einsy end which would be worse case as they are expensive.  You will  need to remove that for a proper visual inspection though.  

Posted : 16/12/2022 7:18 pm
Illustrious Member

Check the fuses.

Measure the resistance of the heatbed - Make sure there is not a dead short.

I agree with @neophyl - replace that connector - plus check the state of the corresponding connector on the Einsy.  Check the tracks around and under it have not been burned out or solder joints melted dry.


Posted : 16/12/2022 8:15 pm
New Member
Topic starter answered:
RE: Bed not heating, middle positive PSU connector burned

Thanks for the replies! I have removed the board from the printer and everything looks fine. No burned leads or components as far as I can see. The terminal the burned wire was connected to is a little discolored but that's just from the heat I assume.

All the fuses look fine and the bed has a resistance of 3 Ohms which I assume is also fine.

I will order a new replacement cable from the Prisma store and hope that fixes it.

Posted : 17/12/2022 4:05 pm