NM-A281 SY8206BQNC 3,3V output issue

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  • rookieme
    Badcaps Veteran
    • Oct 2014
    • 396
    • Greece

    #1

    NM-A281 SY8206BQNC 3,3V output issue

    I have the NM-A281 with fried the KBC.
    I also noticed that the SY8206BQNC [pu401] that provides the 3,3 V gives 3,83V at +3VLP and at +3VALW.
    That must be a good reason why KBC was fried.
    I removed the KBC and measured the parts that regulate the output in my opinion - the PC411, PR407, PR444 and the PC403 are ok.
    Also I replaced the SY8206BQNC but i get the same output that is too high.
    I placed a new KBC and also noticed that U13 burns hot I guess by the efford to regulate down as I get 3,07 & 4,94 at the ouput [no short at output].
    Any suggetions what goes wrong and I get too high voltage instead of 3,3V?
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  • mielta
    Badcaps Veteran
    • Apr 2015
    • 368
    • Germany

    #2
    Re: NM-A281 SY8206BQNC 3,3V output issue

    Hi
    Wich voltage you have on PU401 En1+2
    when you cut PJ402 is the voltage always 3,8V

    Comment

    • rookieme
      Badcaps Veteran
      • Oct 2014
      • 396
      • Greece

      #3
      Re: NM-A281 SY8206BQNC 3,3V output issue

      PU401 pin1 has 3,82V and pin2 0V

      nice, by cutting PJ402 I get 3,34V at +3VALW_P and at +3VLP
      also PU401 pin1 now is 3,33V and pin2 3,76V.

      I'm guessing you have faced that before?

      U13 still runs hot
      Last edited by rookieme; 03-23-2018, 03:55 AM.

      Comment

      • mielta
        Badcaps Veteran
        • Apr 2015
        • 368
        • Germany

        #4
        Re: NM-A281 SY8206BQNC 3,3V output issue

        Check pu402 voltage +5valw

        Comment

        • mielta
          Badcaps Veteran
          • Apr 2015
          • 368
          • Germany

          #5
          Re: NM-A281 SY8206BQNC 3,3V output issue

          i think it is problem +5valw or u13 is defect

          Comment

          • rookieme
            Badcaps Veteran
            • Oct 2014
            • 396
            • Greece

            #6
            Re: NM-A281 SY8206BQNC 3,3V output issue

            +5valw is 5,1 V and seems fine
            ok U13 is faulty, without it and with PJ402 closed I get 3,3V
            now long time waiting for a replacement
            thank you for your time!

            Comment

            • mielta
              Badcaps Veteran
              • Apr 2015
              • 368
              • Germany

              #7
              Re: NM-A281 SY8206BQNC 3,3V output issue

              with pleasure

              Comment

              • islammostafa.me19
                Member
                • Jul 2017
                • 39
                • egypt

                #8
                Re: NM-A281 SY8206BQNC 3,3V output issue

                thanks

                Comment

                • imranromi
                  Badcaps Legend
                  • Jan 2015
                  • 1288
                  • Pakistan

                  #9
                  Re: NM-A281 SY8206BQNC 3,3V output issue

                  Originally posted by rookieme
                  I have the NM-A281 with fried the KBC.
                  I also noticed that the SY8206BQNC [pu401] that provides the 3,3 V gives 3,83V at +3VLP and at +3VALW.
                  That must be a good reason why KBC was fried.
                  I removed the KBC and measured the parts that regulate the output in my opinion - the PC411, PR407, PR444 and the PC403 are ok.
                  Also I replaced the SY8206BQNC but i get the same output that is too high.
                  I placed a new KBC and also noticed that U13 burns hot I guess by the efford to regulate down as I get 3,07 & 4,94 at the ouput [no short at output].
                  Any suggetions what goes wrong and I get too high voltage instead of 3,3V?
                  I face same problem like 10 time problem found sound ic short to gnd..

                  Comment

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