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    iMac logic board fan control question.

    I have a 2010 A1311 iMac motherboard which was possibly damaged by lightning.

    One of the areas damaged was for the CPU fan control where inductor L5720 had exploded.
    Looking at the schematic (below) it is a 0603, and gives the value in ohms and seeing as I have no smd inductors here, it has been replaced with a 220Ω resistor. Without this, the fan will not work.

    The question is more related to the inductor next to it, L5701, which is part of the fans speed control.

    The schematic gives the value again at 220 Ω only it is a 0402 which is much smaller than anything I have here (and is placed on a super-fine trace which I'm not sure would even accomodate the resistors which I do have even if I soldered it on it's side). This one didn't explode but gives a measurement of only 4 ohms.

    Does anyone have any suggestions as to how to resolve this or I'll just leave it as-is and resolve any speed inconsistencies with the Macs Fan Control software?
    Attached Files
    Last edited by Crystaleyes; 08-04-2022, 10:56 AM.

    #2
    Re: iMac logic board fan control question.

    Thinking to just solder a fine wire with a 220R resisitor in the middle, insulated and stuck to the board...

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      #3
      Re: iMac logic board fan control question.

      Ferrite bead not resistor.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

      Comment


        #4
        Re: iMac logic board fan control question.

        Originally posted by piernov View Post
        Ferrite bead not resistor.
        I know that it's supposed to be ferrite but not sure where I can get one. Looking online here in Brazil I can find 150Ω or 330Ω

        Is it so important that it is ferrite?

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          #5
          Re: iMac logic board fan control question.

          Have found a 220 Ω ferrite bead on another old iMac pcb but it's 0805 package is way too large, so shall do the wire trick mentioned earlier.


          Wish me luck!

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