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HISENSE F42K20E 158308 not turning on

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    #1

    HISENSE F42K20E 158308 not turning on

    Hi,
    Just finished repairing a Hisense f42k203. It is the 150308 and E120111.
    Checked P/s voltages with only red led on {would not turn blue}
    XP902 connector
    stb = 3.7v
    5v = 5v
    12v = 12v
    PWM= 0v
    sw = 0v
    18v = 18v

    xp902 had 131v on +1 pin

    Tried EEPROM but that did not work

    While looking for another main board noticed the N4 regulator was very discolored. Checked it out AZ1080D and replaced it with UZ1080L and TV fired up perfect. Also put the original EEPROM back in and it worked perfect.
    The N4 input of 5v was right on and a perfect 3.3v output. Noticed it was still getting very hot so i put a small heatsink on N4.
    Attached Files
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    #2
    Re: HISENSE F42K20E 158308 not turning on

    Nice Hope it keeps working though. Wouldn't think it should get so hot unless something downstream is drawing excess current. Maybe check components around it getting hot also.
    I assume no responsibility for any stupid suggestions I might post.

    Comment

      #3
      Re: HISENSE F42K20E 158308 not turning on

      Something is still drawing too much current, keep an eye on it.
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

      Comment

        #4
        Re: HISENSE F42K20E 158308 not turning on

        Thanks for the reply. TV is still going. Temp. on regulator is around 120f. Maybe a little hotter closer to the 3.3v output on board. I have seen a few other boards with the same discoloration on N4 . I think Bud is right that something is drawing too much current. Maybe if someone has one of these tv's they could let me know how Hot N4 is getting on their TV and if they sense it has overheated.

        Comment

          #5
          Re: HISENSE F42K20E 158308 not turning on

          Here is a board from ebay with same problem. N4 is between the tuner and cpu in center of board. az1084d
          Attached Files
          Last edited by pudgi300; 01-29-2017, 09:52 AM.

          Comment

            #6
            Re: HISENSE F42K20E 158308 not turning on

            Checked the caps near it especially the little ceramic one ?
            Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

            https://www.facebook.com/Telford-Tel...7894576335359/

            Comment

              #7
              Re: HISENSE F42K20E 158308 not turning on

              pulled caps around N4 c311,c48,c46 are 10uf low esr c50 and c47 are .1uf c18 is 4.6uf low esr R28=110 ohms r29=180 ohms r79=4.7k r80=4.6k

              TV is still working fine except n4 heat The STB is 3.7v so with no schematic don't know if that is correct.

              Later

              Comment

                #8
                Re: HISENSE F42K20E 158308 not turning on

                Could it just be a trashy design which runs the regulator hard?

                What if there was too high ripple going into it?
                Last edited by Agent24; 01-29-2017, 06:07 PM.
                "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                -David VanHorn

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