accidentally shorted my fan out



  • I was trying to be clever and put connectors on my hot end and fans to make swapping them easier, but when I was testing the fans I heard a snap, and noticed that I had shorted my part fan out. (YIKES!) The fuses check out good, and I don't see any obvious scorch marks on the board.

    All my other fans work, but yeah, I'm kinda bummed.

    is it an easy fix, or is the whole board pretty much toast?

    it's a duet 2 wifi PCB version 1.04b if that matters.


  • administrators

    It's likely that the mosfet controlling that fan output has failed. It can be replaced, but it's quite tricky for an inexperienced user. Search this forum for "replace fan mosfet".



  • I made the same mistakes .
    https://forum.duet3d.com/topic/1639/short-to-fan-2
    If you have the right tools it isn't difficult.
    I made the work with a soldering station air gun for removing the burned mosfet and a soldering iron for soldering the new one
    You need also a peace of kapton tape for protect the surroundings parts of the board from the hearing of the air gun
    good luck



  • If you don't have hot air you can try two other options

    put enough solder on a big tip soldering iron to cover the whole transistor and it will likely come off inside the blob of solder.

    carefully cut the pins off the transistor and remove the remainder one at the time, however it can be easy to lift the traces of the board if not very careful when cutting.



  • If you don't have the tool or the experience to replace the mosfet, you can take the board and a new mosfet to a local technician (e.g. a cell phone repair shop) and ask them to replace it. A new mosfet will cost you almost nothing + shipping at digikey.com

    Or, move the fan to an unused fan output? (e.g. Fan2).


  • administrators

    The difficult part is removing the old MOSFET without lifting the PCB traces. When you have done that, the new MOSFET can be soldered in place using a fine-tipped soldering iron.

    This video may help: https://youtu.be/LADgxZgyJ04. I suspect that one of the reasons that he finds adding solder helps is that he is using leaded solder, which has a lower melting point than the unleaded solder that was used when the board was manufactured. It's easier with low melting point solder such as ChipQuik.



  • worth noting that if you use low melting point solder its important to remove all of it before soldering in the new part.

    you'll get a basic hotair station for around $20, a quite usable one for around $30, compared to the cost of the duet might be worth while investment. i find the hot air useful for unclogging nozzles and touching up parts after removing supports and rafts as well.


  • administrators

    @bearer said in accidentally shorted my fan out:

    i find the hot air useful for unclogging nozzles and touching up parts after removing supports and rafts as well.

    ...and shrinking heatshrink sleeving.


 

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