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    #1

    LG tv no power

    Hi guys, I live in Thailand and was a proud owner of a LG50LB650T smart tv. One night we had an electrical storm and next morning my tv would not fire up and it had blown my external speakers too.
    I did some research on the internet and everything seemed to point to the power board. I took the back off and was expecting to see some blown caps or something, but nothing. I ordered a power board from ebay and it arrived last week, but unfortunately the postman thought he could get a 8inch board in 6inch letterbox, it ended up bent and broken.
    So I thought maybe I could use the parts off the broken one to repair my original one. I have took voltage readings from the connection that goes to the main board and here they are.

    Gnd.........
    12V.........17V
    12V..........17V
    Gnd..........
    24V..........0V
    Gnd
    3.5V.........3.5V
    3.5V.........3.5V
    PWR on.....0V

    Should I have constant power power at the pwr on block?
    Thanks guys.
    Attached Files
    Tags: None
    #2
    Re: LG tv no power

    Originally posted by vogie View Post
    Hi guys, I live in Thailand and was a proud owner of a LG50LB650T smart tv. One night we had an electrical storm and next morning my tv would not fire up and it had blown my external speakers too.
    I did some research on the internet and everything seemed to point to the power board. I took the back off and was expecting to see some blown caps or something, but nothing. I ordered a power board from ebay and it arrived last week, but unfortunately the postman thought he could get a 8inch board in 6inch letterbox, it ended up bent and broken.
    So I thought maybe I could use the parts off the broken one to repair my original one. I have took voltage readings from the connection that goes to the main board and here they are.

    Gnd.........
    12V.........17V
    12V..........17V
    Gnd..........
    24V..........0V
    Gnd
    3.5V.........3.5V
    3.5V.........3.5V
    PWR on.....0V

    Should I have constant power power at the pwr on block?
    Thanks guys.
    I have tried uploading 3 photos, but only one seems to appear.
    Attached Files

    Comment

      #3
      Re: LG tv no power

      The power on signal is generated by the main board, when TV is OFF the signal is <1VDC, when the power switch is activated then it goes to >2.5Vdc to turn on the rest of the power supply.
      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: LG tv no power

        Originally posted by budm View Post
        The power on signal is generated by the main board, when TV is OFF the signal is <1VDC, when the power switch is activated then it goes to >2.5Vdc to turn on the rest of the power supply.
        Thanks for the reply.

        I failed to mention that I have the standby light on the tv.

        I do not have the 1v going to the pwr on/drv on connection.

        Comment

          #5
          Re: LG tv no power

          Originally posted by vogie View Post
          Thanks for the reply.

          I failed to mention that I have the standby light on the tv.

          I do not have the 1v going to the pwr on/drv on connection.
          You have standby light because the standby power supply section is working, the power supply needs that POWER-ON of >2.5VDC to turn on the rest of the power supply.
          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

            #6
            Re: LG tv no power

            after a lightening strike/storm a lot of mainboards have issues maybe look at the main board for blown parts etc.

            Comment

              #7
              Re: LG tv no power

              Originally posted by vinceroger69 View Post
              after a lightening strike/storm a lot of mainboards have issues maybe look at the main board for blown parts etc.
              Thanks for the reply. I will have a look at the main board today, could that also account for no power on the 'pwr on/drv on' connector on the power board?

              Comment

                #8
                Re: LG tv no power

                Originally posted by vogie View Post
                Thanks for the reply. I will have a look at the main board today, could that also account for no power on the 'pwr on/drv on' connector on the power board?
                Visually there are no signs of arcing or damaged componants, no sign of anything untoward.

                Comment

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