Lg 42lk450-uh

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  • itronic
    Senior Member
    • Sep 2015
    • 82
    • usa
    #1

    Lg 42lk450-uh

    Hi guys i have a LG 42LK450. It will not turn on. It has the red standby light on. With the main board unplug , I can jump pin 9 to pin 1 on p201 connector on PSU and the backlight will come on. Also all the voltages seems to be on each pin on the p201 connector. But wont come on when plug in to mainboard. Below is the readings i took with the mainboard unplugged.

    P201 connector on PSU

    Not jump:

    1,3,5,7 no reading
    9-3.5v
    11-3.5v
    13,15,17,19,21,23 no reading
    2,4,6,8 no reading
    10-3.5v
    12-3.5v
    14,16,18,20,22,24 no reading.


    Now I jump pin 9 to pin 1 on p201 connector on PSU

    1-3.5v
    3-24v
    5,7 0.5 v
    9-3.5v
    11-3.5v
    13,15-.05v
    17-12.v
    19-12v
    21-12v
    23-1.25v

    2-24v
    4-24v
    6,8-0.5v
    10,12-3.5v
    14,16-0.5v
    18-4.4v
    20-7v
    22-this goes dim when i touch red lead to it. goes from 12v to 4v. different each time.
    24-0.5v.

    Anyone Got an idea what to look at next. Im think main board. But could the backlight be shorted. thats odd it would dim when checking with meter on pin 22.
    Tags: None
    • CapLeaker
      Leaking Member
      • Dec 2014
      • 8146
      • Canada
      #2
      Re: Lg 42lk450-uh

      Well... first off the voltages measured mean nothing if we don't know the corresponding pin name. So please add the pin out names to the measured voltages. I am thinking PSon isn't coming from the main board to turn the PSU on. So yes, you may need a new main board.
      Last edited by CapLeaker; 09-16-2017, 04:02 AM.

        Comment

        • itronic
          Senior Member
          • Sep 2015
          • 82
          • usa
          #3
          Re: Lg 42lk450-uh

          Here is pictures of boards and PIN numbers on PSU. Sorry about that.

          pin numbers.

          1.pwr on 2. 24v
          3. 24v 4. 24v
          5.gnd 6. gnd
          7. gnd 8. gnd.
          9. 3.5v 10. 3.5v
          11. 3.5v 12. 3.5v
          13. GND 14. GND
          15. GND 16. GND
          17. 12V 18. INV
          19. 12V. 20. A. DIMM
          21. 12V 22. P. DIMM
          23. NC 24. ERROR













          Attached Files
          Last edited by itronic; 09-16-2017, 09:03 AM.

            Comment

            • CapLeaker
              Leaking Member
              • Dec 2014
              • 8146
              • Canada
              #4
              Re: Lg 42lk450-uh

              The problem is on the main board with that big main IC, XD printed on there. Depending you capabilities, you can try to reflow that main IC, or get a new main board.

                Comment

                • itronic
                  Senior Member
                  • Sep 2015
                  • 82
                  • usa
                  #5
                  Re: Lg 42lk450-uh

                  Ok thank you for your response. So should i reball it or just reflow it.

                    Comment

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