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Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

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    #1

    Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

    Ok guys, this is what I have so far. I tested the power supply. All my voltages out are pretty much in range. I proceeded to the main board and started testing regulators. I came to U707. Voltage in is reading 3.23v. I'm getting a voltage reading of .33v out. I looked at the data sheet and i am supposed to have a 1.8v dropout. So i believe I should have 1.8v out?? Not .33v. I already ordered the part from digikey and replaced. I am still getting the same readings and still no luck with the TV. Now the regulator at U709 Is giving me a reading at .39v in and nothing out. I believe the problem would lie somewhere inbetween the U707 and U709. I am a newb at this stuff so any suggestions or help would be greatly appreciated. Thanks in advance.
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    #2
    Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

    Did you Ohm out the output of the regulator to see if it feeding into shorts circuits and it may take out your new regulator if the shutdown circuits of the regulator does not shutdown fast enough.
    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

      #3
      Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

      Not sure how to ohm it out. Can you help me out?

      Comment

        #4
        Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

        TV unplugged and let the power supply capacitors drain out for 5 minutes, set the meter to Ohm mode, black lead to the chassis, red lead to the output leg of the regulator, see what you get.
        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

          #5
          Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

          Ok, I have mainboard out of the TV so I set my multimeter to ohms, black lead on ground around screw hole for chassis and red lead on tab of regulator on U707 here's what i got. 000.6 ohms..

          Comment

            #6
            Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

            Now how do I find where the short is??

            Comment

              #7
              Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

              That is the hard part since it goes to lots of places, it the output pin the middle pin? P/N?
              You may have shorted CAP (MLCC TYPE). There should a lot of filter connected to the output of the regulator, you may have to remove them one at a time to see if shorts go away.
              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

                #8
                Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

                Yes the center pin is the output. Now, the first cap after the pin is labeled C743 and the last cap on the circuit before the next regulator is labeled C749. So if I am correct all banks on the circuit where the short is would be 743-749. Is it correct the circuit runs in numerical order??

                Comment

                  #9
                  Re: Need some help on Insignia NS-LCD47HD TV No Picture No sound. Blue led comes on.

                  Basically I'm uncertain how to trace the circuit.

                  Comment

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