Fan stopped working mid print, Always on is burned now.



  • Hello people.

    Yesterday I was printing something and in the mid of the print i just heard a weird "pop" and the fan that is connected to always on stopped working. I paused the print, turned the printer off and went to inspect. I noticed that there is a black spot under one of the connectors on the board for the fan. This was the only fan connected and after I checked the board I couldn't find any burned components besides the one mentioned. Today I checked the connectors with a Voltmeter and at first it showed 11.5V on the always on fans and PWM fans voltage changed normally as I changed the speed of the fan in the DWC. I checked if the printer is working and everything is fine except for all the fan ports. Then I checked again and it displayed around 6v on each of the connectors. When I connect a fan to any pins it's not working. Can somebody please help me, the board is about a month old and it's not really useful without the fans. Here are a few pics, sorry for the bad quality, I took them with a cheap endoscope camera




  • administrators

    It's a bit hard to tell from your photos, but it looks to me that you have some burn marks emanating from the ground pin of the first always-on fan connector. I think this can only mean that you had a short in the fan wiring between the two wires, because it would take a severe current overload to cause that amount of burning. That would also explain why none of the fans is now working. When there is a short in the fan wiring, usually one of the vias on the PCB fails before anything else, which disconnects the VIN side of the fan voltage selection jumper block from VIN.

    To check this out, use a multimeter to measure the resistance between the VIN pin of the fan voltage selection jumper block and the positive terminal of the VIN terminal block. It should be as low as your multimeter can measure.

    The good news is that you can easily add a bypass wire on the back of the board between those two points, which should get all the fans working again. But I advise you to identify what caused the short in the first place, and make sure that it can't happen again.

    HTH David



  • Hi dc42,

    Thank you for the reply.

    Indeed it is burned on the ground pin. But what caused it I can't explain as the fan that was used is still working normally and there was no possibility of a shortage (i took extra care when I wired everything to the board). Unless there is something wrong with the electronics of the fan itself that might have caused this, guess I'll never know. Anyhow I checked the resistance and the multi-meter doesn't even react when I check the resistance between these two points, so I guess that the resistance is below the measurement capability of my multi-meter (it's a cheap Chinese one). Now before I start soldering (I never did a PCB bypass before) can you confirm that these are the correct pins to put a wire on? I don't want to fry the board 🙂


  • administrators

    Yes those are the correct pins.

    I checked the PCB layout files to see if there is anything else that could cause a burn in that area, but there isn't.

    Apart from an external short, the only other possibility I can think of is a short underneath the fan connector itself. With care it is usually possible to pull the plastic part of the connector off, leaving just the pins behind. That would allow you to inspect the area between the pins.



  • Well I soldered it and it works like a charm now. Thank you so much for your help. Have a nice day, I hope it's sunny in the UK as it is in Ireland today 🙂


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