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LG 55LW5300 Backlights on, "Black Screen"

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    #1

    LG 55LW5300 Backlights on, "Black Screen"

    Hello all, I was given an LG 55LW5300. When plugged in I get backlights but no picture. I checked voltages and found the Power On voltage to be 3.4V instead of 24v. All other voltages are normal at a powered on state. I did look around for solutions and found it could possibly be the IC's needing reflowed. I did this with my hot air rework station and this did not solve the issue. I'm not above replacing a board but I'd like to know which board it might be. Seems like a motherboard problem to me but I'm not 100% sure. Any ideas what the problem could be? Photos attached of boards and TV at On state. Note: I temporarily removed the heat sink on the main IC when I reflowed the solder.
    Attached Files
    Last edited by SmartSped; 05-07-2023, 11:01 AM.
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    #2
    Re: LG 55LW5300 Backlights on, "Black Screen"

    Could be nand and spi, see if panel gets sca. Could also be a panel level short or tcon.
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      #3
      Re: LG 55LW5300 Backlights on, "Black Screen"

      What's an SCA and how do I check it?

      Also I'd like to correct something from my opening post. I didn't see there were a second row of pins on the main connector between the power board and main board. The power on pin reads 3.4v and the pin under it reads 24v. I checked all voltages on the second layer and they were all fine. No voltage on the error pin.
      Last edited by SmartSped; 05-07-2023, 02:38 PM.

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        #4
        Re: LG 55LW5300 Backlights on, "Black Screen"

        service manual
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          #5
          Re: LG 55LW5300 Backlights on, "Black Screen"

          Originally posted by lotas View Post
          service manual
          Thanks, I checked the power on flow chart and seemed to be getting voltage everywhere it wants me to check. Everything seemed normal.

          I also tried to navigate to the cable channel to see if I have sound but I can't hear anything.

          Also, is it normal for the main IC to get too hot to touch after about 30 seconds of powering on (touching the heat sink)?

          Lastly, the TV started shutting off on its own after about 25 seconds of operating and turning back on. It wasn't doing this before.

          EDIT: Just looked at the T-Con board and the shielding and ribbon cables look a little toasty to me. Photos attached.
          Attached Files
          Last edited by SmartSped; 05-07-2023, 04:03 PM.

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