Problems with the PWM Module P0



  • Hello at all!
    I got serious Problems with my duet wifi recently. One Fan of my 3d printer stopped working. It is connected to the PWM Port P0. The cable was broken so i fixed it. Then the fan was working a time. Suddenly it stopped again. I turn the printer off and cecked the wires once again. There were no problems. After turning te Printer on it still doesn´t work. After turning of I change the Fans from Fan1: P0 to P2 and Fan2: P2 to P0. with the code "M106 P0 S0" and "M106 P0 S1" i checked both ports if they were working. Fan1 was working fine; Fan2 din´t do anything.
    When measuring the Port P0 a measured 23.88V with the code "M106 P0 S0" and 20V with the "M106 P0 S1"🤔
    Could you help me please becaus actually I don´t know what it is...
    Thanks a lot!!!
    0_1535356879863_config.txt


  • administrators

    It sounds to me that the Fan0 mosfet has failed, probably due to the faulty cable or a fan short. It can be replaced, but it's tricky without the right soldering equipment. Repair services are available in the UK and US.



  • Hello Thanks for responding!
    What would a Repair cost? Is it possible to avoid this failrure in future by using external mosfets and the duet will control these external mosfets?


  • administrators

    For simple repairs in the UK such as replacing fan mosfets, I charge £20 + return carriage + 20% VAT. For repairs in the US, ask forum user W3DRK for a price.

    If your E1 heater output is free then the 2.02beta1 release of RRF allows you to remap a fan to the Heater 1 output. Note, heater outputs don't have internal flyback diodes, so if you want to connect a brushed DC motor (e.g. Berd Air or other air pump) to one, you need to use an external flyback diode.

    As long as you only connect ordinary brushless DC fans to the fan outputs, and take care not to short them or connect the fan the wrong way round, the fan outputs are reliable. But a short circuit between the two output pins of the fan connector will usually blow the fan mosfet before the fuse can protect it. Connecting a fan the wrong way round can have the same effect, depending on the fan - or it may blow the fan instead, or neither.



  • good Morning dc42!
    Thanks a lot for the quick support. Ok, i can´t guarentee that when the cabels broke up the don´t touch each other. Might seem this would be the reason.
    Now I wanna try to find a Company near by which could realize the change of the mosfet. Which soldering equipment is needed for replacement so I can ask the companies.
    At home I got an old Ersa soldering station with a 24v micro tool which have a quite small top. How is the Sparepartnumber of the mosfet or which type is it?


  • administrators

    @tekkineo, there is a wiki page listing the spare part numbers.

    To remove the old mosfet without damaging the PCB you need either hot air rework equipment or very low melting point solder such as ChipQuik. Also solder wick to remove the old solder. Fitting the new mosfet is easy with a small-tipped soldering iron and fine solder.



  • Hello perfect! Thanks a lot! I would take a look around to find a vendor whicht could change it!
    Actually in the internet i only found a mosfet called PMV40UN2R and not PMV40UN2. In the datasheets i didn´t find a difference. Can I use the PMV40UN2R?
    Thank you very very much!


  • administrators

    According to https://www.nexperia.com/products/mosfets/small-signal-mosfets/PMV40UN2.html the type number is PMV40UN2 and the orderable part number is PMV40UN2R.



  • Ok Perfect!!!
    Thank you very much!!! I got it! I will order the parts and take a look for a vendor in germany. If i can´t find anyone I´ll have to send it to uk 🙂


  • administrators


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