LG 55LV5500-UA no picture or sound

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  • electrobe
    Senior Member
    • Sep 2012
    • 70
    • usa

    #1

    LG 55LV5500-UA no picture or sound

    I have a LG 55LV5500-UA led smart tv that has no picture or sound when powered on. When the tv is turned on it powers on & the lg logo display for a couple of seconds then go off. There is no picture or sound just backlights staying on. I removed the rear cover to check for popped capacitors but there were none. I would appreciate any help.
  • Hamie
    Badcaps Legend
    • Apr 2014
    • 1383
    • UK

    #2
    Re: LG 55LV5500-UA no picture or sound

    Probably another led failure.
    Upload pictures of the boards

    Comment

    • electrobe
      Senior Member
      • Sep 2012
      • 70
      • usa

      #3
      Re: LG 55LV5500-UA no picture or sound

      Here are the pictures you have requested. I even took a picture of the backlights on when the power is turned on.
      Attached Files

      Comment

      • Diah
        Badcaps Legend
        • Feb 2013
        • 6358
        • Germany

        #4
        Re: LG 55LV5500-UA no picture or sound

        Hamie correct, LG 55 had 2 strips, even half of one strip ligh <ou will see backlight

        first check the backlight voltage one by one, which one read higher at turn on.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: LG 55LV5500-UA no picture or sound

          "There is no picture or sound just backlights staying on" So the backlights are actually staying ON and will go off if you turn off the power switch but you cannot see any images on the screen?
          "lg logo display for a couple of seconds" LG logo on the BEZEL or actually LG image on the LCD screen?
          Are you getting 12 DCV (DCV depends on the panel design) on both ends of the SMD fuse on the T-CON board?
          Last edited by budm; 03-31-2016, 01:44 PM.
          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

          • Diah
            Badcaps Legend
            • Feb 2013
            • 6358
            • Germany

            #6
            Re: LG 55LV5500-UA no picture or sound

            LV series of LG had in SW semi protection level. which turn off PWB off to protect other parts at main board to get damage.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #7
              Re: LG 55LV5500-UA no picture or sound

              LG EAY62169901 (EAX62876201/8) Power Supply 55LV5400 55LV5500 55LW5300 55LW5700

              To OP, If you look at the LED connectors, you will see pin labels as 1A~C (4 STRINGS), 2A~C (4 STRINGS), 3B~C (4 STRINGS), and 4A~C (4 STRINGS) so you have total of 16 strings thus 16 Power MOSFETs for the 16 LED Cathodes return lines.
              Attached Files
              Last edited by budm; 03-31-2016, 02:47 PM.
              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

              • electrobe
                Senior Member
                • Sep 2012
                • 70
                • usa

                #8
                Re: LG 55LV5500-UA no picture or sound

                Yes the backlights stay on when the set is powered on & turn off when turned off. The LG logo is displayed on the screen & then disappears after a few seconds. I will check the voltages of the (16) mosfets & for 12DCV SMD fuse on the T-CON board if it has one.

                Comment

                • electrobe
                  Senior Member
                  • Sep 2012
                  • 70
                  • usa

                  #9
                  Re: LG 55LV5500-UA no picture or sound

                  Here are the voltages from the smd fuse from t-con & backlight voltages (each point being tested when powered on)

                  T-con smd fuse both sides 10.91 V

                  Starting from the lower left power ic:
                  1.) 12.50V at turn on then 1.6V
                  2.) 12.50V at turn on then 1.5V
                  3.) 12.50V at turn on then 1.3V
                  4.) 12.7V at turn on then 1.3V
                  5.) 12.8V at turn on then 1.3V
                  6.) 12.7V at turn on then 1.3V
                  7.) 12.3V at turn on then 1.3V
                  8.) 12.5V at turn on then 1.3V
                  9.) 12.1V at turn on then 1.1V
                  10.) 13V at turn on then 1.3V
                  11.) 12.7V at turn on then 1.1V
                  12.) 13V at turn on then 1.4V
                  13.) 12.4V at turn on then 1.2V
                  14.) 12.5V at turn on then 1.2V
                  15.) 12.4V at turn on then 1.3V
                  16.) 12.6V at turn on then 1.5V

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: LG 55LV5500-UA no picture or sound

                    "Starting from the lower left power ic:" Which IC is that? Do you mean the 16 Power MOSFETs? If those are what you are seeing, they are OK, as you indicated, the backlights STAY ON, if there was an error the backlights will be commanded to turn OFF ALL the LEDs.
                    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

                    • electrobe
                      Senior Member
                      • Sep 2012
                      • 70
                      • usa

                      #11
                      Re: LG 55LV5500-UA no picture or sound

                      Yes the (16) power mosfets

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: LG 55LV5500-UA no picture or sound

                        So you do have Voltage to the T-CON that means the main board did not go into standby mode otherwise the DCV for the T-CON will not be there and the backlights also stay on, but you have no image on the screen so either the main board stops sending the signals to T-CON or something is going on with T-CON.
                        Try having one ribbon cables between the T-CON and the LCD panel connected one at time to 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

                        • electrobe
                          Senior Member
                          • Sep 2012
                          • 70
                          • usa

                          #13
                          Re: LG 55LV5500-UA no picture or sound

                          I disconnected each ribbon cable going to the screen & nothing was displayed. The backlights stayed on & now the LG logo no longer shows on the set when turned on.

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #14
                            Re: LG 55LV5500-UA no picture or sound

                            Make sure the ribbon cables are properly seated back in place.
                            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

                            • electrobe
                              Senior Member
                              • Sep 2012
                              • 70
                              • usa

                              #15
                              Re: LG 55LV5500-UA no picture or sound

                              I went back & made sure the ribbon cables were properly seated & still no LG logo displayed on the screen. The backlights stay on but that is it.

                              Comment

                              • Diah
                                Badcaps Legend
                                • Feb 2013
                                • 6358
                                • Germany

                                #16
                                Re: LG 55LV5500-UA no picture or sound

                                Originally posted by electrobe
                                I went back & made sure the ribbon cables were properly seated & still no LG logo displayed on the screen. The backlights stay on but that is it.
                                regarding to the age of the TV and environment, the Gold print on ribbon cables became very sensitive at take out and reset, check them with magnifier after you had back LG Logo take it in parts and follow post no 2.

                                Comment

                                • comptek
                                  Badcaps Veteran
                                  • Aug 2013
                                  • 606
                                  • uk

                                  #17
                                  Re: LG 55LV5500-UA no picture or sound

                                  Does Menu show up ?

                                  Comment

                                  • electrobe
                                    Senior Member
                                    • Sep 2012
                                    • 70
                                    • usa

                                    #18
                                    Re: LG 55LV5500-UA no picture or sound

                                    I will check the ribbon cable pins under magnification & will report back. The menu doesn't show either. I did find one possible cause though when I was searching the back of the main input board. I found a burned 3-pin chip with the markings (X75A) with (16) written under it. I will upload a picture of it tomorrow.

                                    Comment

                                    • electrobe
                                      Senior Member
                                      • Sep 2012
                                      • 70
                                      • usa

                                      #19
                                      Re: LG 55LV5500-UA no picture or sound

                                      Here is a picture of the burned chip. I do not know what it is yet from the markings I previous stated.
                                      Attached Files

                                      Comment

                                      • electrobe
                                        Senior Member
                                        • Sep 2012
                                        • 70
                                        • usa

                                        #20
                                        Re: LG 55LV5500-UA no picture or sound

                                        I found out the part is a "P-Channel Enhancement Mode Field Effect Transistor" & is located in the "panel power" section on the main board. I do not have one of these on hand to replace to see what will happen.

                                        Comment

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