LG 42LV 4400 Will not come on

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  • davg
    Badcaps Veteran
    • Sep 2008
    • 536
    • Canada

    #21
    Re: LG 42LV 4400 Will not come on

    Tks appreciate your advise. With the power button pressed I read 0.48v which I believe is 0 volts this is the same as just plugged in and sitting in standby.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #22
      Re: LG 42LV 4400 Will not come on

      So the PS-ON is present but basically no VCC to run the PFC IC, so you will need to dig deeper down to component level by tracing out the board to locate the switched Transistor that supplies the VCC to run the PFC IC. It is not going to be easy but can be done, it is a matter of tracing the VCC pin back to the switched Voltage source.
      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

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #23
        Re: LG 42LV 4400 Will not come on

        Parts for your TV:
        http://www.shopjimmy.com/catalogsear...q=LG+42LV+4400

        EEPROM:
        http://www.shopjimmy.com/lg-42lv4400...eprom-only.htm
        http://www.shopjimmy.com/lg-cov31310...2lv4400-ua.htm

        You may have problem with two boards.
        Last edited by budm; 06-04-2018, 10:34 AM.
        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

        • davg
          Badcaps Veteran
          • Sep 2008
          • 536
          • Canada

          #24
          Re: LG 42LV 4400 Will not come on

          Ya I am kinda rusty at this been several years since I've done this. I was looking for a schematic of the board but nothing so far.
          This problem seemed intermittent; my friend who owned the TV had the problem had it setting in the original box for about a year gave it to me to check it out when I got it home plugged it in it worked fine for a whole day before the condition came back. I turned it on and off several times then left it powered on for approx. 6 hrs when I turned it off for the night the next morning it would not power on???

          Comment

          • davg
            Badcaps Veteran
            • Sep 2008
            • 536
            • Canada

            #25
            Re: LG 42LV 4400 Will not come on

            Tks for the source but I do believe shopjimmy will not ship to Canada but I did source a used board on ebay

            Comment

            • davg
              Badcaps Veteran
              • Sep 2008
              • 536
              • Canada

              #26
              Re: LG 42LV 4400 Will not come on

              Originally posted by budm
              So the PS-ON is present but basically no VCC to run the PFC IC, so you will need to dig deeper down to component level by tracing out the board to locate the switched Transistor that supplies the VCC to run the PFC IC. It is not going to be easy but can be done, it is a matter of tracing the VCC pin back to the switched Voltage source.
              Will that switched transistor be located on the main power board or the logic board? should I have any other voltages present on the main board connector when the board is powered on in standby or just the 5 vdc present

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #27
                Re: LG 42LV 4400 Will not come on

                That switched transistor will be on the power supply board. Right now the power supply board is getting the PS-ON fine, it is the power supply board that is not working.
                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

                • davg
                  Badcaps Veteran
                  • Sep 2008
                  • 536
                  • Canada

                  #28
                  Re: LG 42LV 4400 Will not come on

                  Tks Budm truly appreciate it and since my skills are lacking and I can buy a replacement board for 60 bucks its a no brainer just wanted to make sure I was replacing the right board

                  Comment

                  • davg
                    Badcaps Veteran
                    • Sep 2008
                    • 536
                    • Canada

                    #29
                    Re: LG 42LV 4400 Will not come on

                    Originally posted by budm
                    That switched transistor will be on the power supply board. Right now the power supply board is getting the PS-ON fine, it is the power supply board that is not working.
                    Tks Budm just received the replacement board but the symptoms are the same have 5.2v stand-by power but still will not power on? Unless the two boards has the same defect leads me to think the problem must be elsewhere?

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #30
                      Re: LG 42LV 4400 Will not come on

                      Originally posted by davg
                      Tks Budm just received the replacement board but the symptoms are the same have 5.2v stand-by power but still will not power on? Unless the two boards has the same defect leads me to think the problem must be elsewhere?
                      So the new power supply board with PS-ON forced on and still no PFC Boosted Voltage? If that is the case then your new power supply board is bad, you need to have that boosted Voltage when PS-ON is present.
                      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

                      • Andrew F. Ali
                        Badcaps Legend
                        • Jan 2014
                        • 2450
                        • Trinidad & Tobago

                        #31
                        Re: LG 42LV 4400 Will not come on

                        Disconnect the connector going from the PSU to the Main Bd. I couldn't make out the pin Nos. from the poor quality pics you posted. Anyway, you would need two (2) 1k Ohm resistors. Connect one end of a 1k Ohm resistor on the pin labeled Std-By and the other end to the pin labeled PS-ON. Plug the PSU into the ac. Measure the other pin and see if the voltages labeled on the connector appear. If they don't then the PSU is no good. If they do, leaving the 1st resistor in place, connect the other 1k Ohm resistor on the Std-By pin and BL-ON pin. Connect the backlights and apply the ac. The backlights should come ON and stay ON. If it does that then the PSU is perfect if it doesn't then the PSU/Inv Driver has a problem.

                        Comment

                        • davg
                          Badcaps Veteran
                          • Sep 2008
                          • 536
                          • Canada

                          #32
                          Re: LG 42LV 4400 Will not come on

                          Originally posted by budm
                          So the new power supply board with PS-ON forced on and still no PFC Boosted Voltage? If that is the case then your new power supply board is bad, you need to have that boosted Voltage when PS-ON is present.
                          That is quite possible since it is a used board?

                          Comment

                          • davg
                            Badcaps Veteran
                            • Sep 2008
                            • 536
                            • Canada

                            #33
                            Re: LG 42LV 4400 Will not come on

                            Thank you Andrew sorry for the poor quality photo maybe this one will be better it shows the connector from the power supply to the main board. The pins are 1,2,3,- 5.1vsb (Remote_ on/off), 4,5,6,7 are ground, 8 & 9 - 12.6v, 10 - pwm1, 11 - pwm2, & 12 - pwm3 (BL_ on/off.
                            Not sure which pins are Std-By and PS-ON
                            Attached Files
                            Last edited by davg; 06-13-2018, 11:53 AM.

                            Comment

                            • davg
                              Badcaps Veteran
                              • Sep 2008
                              • 536
                              • Canada

                              #34
                              Re: LG 42LV 4400 Will not come on

                              Sorry I am not sure if I am reading the markings on this connector correctly?? I think the pins should be as follows; 1,2 Remote_ on/off, 3- 5.1VSB, 4,5,6,7 SGND, 8 & 9 - 12.6v, 10,11 BL_ON/OFF, 12 PWM1, 13 PWM2, 14 PWM3
                              Attached Files

                              Comment

                              • budm
                                Badcaps Legend
                                • Feb 2010
                                • 40746
                                • USA

                                #35
                                Re: LG 42LV 4400 Will not come on

                                DELTA DPS-131BP
                                LG COV31149501 (0500-0607-0240) Power Supply for 42LV4400-UA
                                Pictures provided by shopjimmy.

                                Pin 10 is the REMOTE ON/OFF (PS-ON) as printed on the board '(CN201 - 10) REMOTE_ON/OFF.
                                So the report on post #5 is not correct.
                                Attached Files
                                Last edited by budm; 06-14-2018, 09:24 AM.
                                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

                                • davg
                                  Badcaps Veteran
                                  • Sep 2008
                                  • 536
                                  • Canada

                                  #36
                                  Re: LG 42LV 4400 Will not come on

                                  Originally posted by budm
                                  DELTA DPS-131BP
                                  LG COV31149501 (0500-0607-0240) Power Supply for 42LV4400-UA
                                  Pictures provided by shopjimmy.

                                  Pin 10 is the REMOTE ON/OFF (PS-ON) as printed on the board '(CN201 - 10) REMOTE_ON/OFF.
                                  So the report on post #5 is not correct.
                                  Thanks for clearing that up Budm so pins 1,2,3 are common 5.1 VSB. That means I do not have the 5 VSB on pin 10 ps-on? And there is still no voltage when the switch is activated
                                  Last edited by davg; 06-14-2018, 10:12 AM.

                                  Comment

                                  • davg
                                    Badcaps Veteran
                                    • Sep 2008
                                    • 536
                                    • Canada

                                    #37
                                    Re: LG 42LV 4400 Will not come on

                                    Originally posted by Andrew F. Ali
                                    Disconnect the connector going from the PSU to the Main Bd. I couldn't make out the pin Nos. from the poor quality pics you posted. Anyway, you would need two (2) 1k Ohm resistors. Connect one end of a 1k Ohm resistor on the pin labeled Std-By and the other end to the pin labeled PS-ON. Plug the PSU into the ac. Measure the other pin and see if the voltages labeled on the connector appear. If they don't then the PSU is no good. If they do, leaving the 1st resistor in place, connect the other 1k Ohm resistor on the Std-By pin and BL-ON pin. Connect the backlights and apply the ac. The backlights should come ON and stay ON. If it does that then the PSU is perfect if it doesn't then the PSU/Inv Driver has a problem.
                                    Following your instructions I do get 12v and the backlights will come on and stay on? so the PSU/Inver Driver test ok??
                                    Last edited by davg; 06-14-2018, 03:50 PM.

                                    Comment

                                    • davg
                                      Badcaps Veteran
                                      • Sep 2008
                                      • 536
                                      • Canada

                                      #38
                                      Re: LG 42LV 4400 Will not come on

                                      So the main logic board is not switching the 5vdc to the ps-on pin. Reading the troubleshooting guide would seem to indicate a bad switching transistor? What are the probable causes
                                      Last edited by davg; 06-14-2018, 06:31 PM.

                                      Comment

                                      • davg
                                        Badcaps Veteran
                                        • Sep 2008
                                        • 536
                                        • Canada

                                        #39
                                        Re: LG 42LV 4400 Will not come on

                                        Originally posted by budm
                                        DELTA DPS-131BP
                                        LG COV31149501 (0500-0607-0240) Power Supply for 42LV4400-UA
                                        Pictures provided by shopjimmy.

                                        Pin 10 is the REMOTE ON/OFF (PS-ON) as printed on the board '(CN201 - 10) REMOTE_ON/OFF.
                                        So the report on post #5 is not correct.
                                        Maybe I should start a new tread since some of the info I gave is incorrect? However the symptoms are the same the unite will not power on. I have the red indicator light on the front, I have 5vdc standby power but I do not have the 5 vdc at the PS-ON #10 pin when the power button is activated (or should I have it always)? The power supply board tested ok with the 1K resister from standby pin to PS-ON pin and the backlights came on and stays on with the extra 1k Resister from standby to BL-ON pin. What would happen if I placed the 1K resister form SBP to PS-ON Pin with both boards connected? What should I look for that would cause the logic board not to switch the 5 vdc? or is the 5 vdc switched by activating the power on switch or the remote on switch. Where can I read to get more understanding of this process? I apologize if these are stupid questions but I am a learner with lots to learn and would take a lot of satisfaction from this to make it work.

                                        Comment

                                        • budm
                                          Badcaps Legend
                                          • Feb 2010
                                          • 40746
                                          • USA

                                          #40
                                          Re: LG 42LV 4400 Will not come on

                                          Right now the problem is on the main board, what the exact cause for it not to send PS-ON (<1Vdc = OFF, >2Vdc = ON) I do not know. You may try heating and cooling the main board to see if the PS-ON will be present or not.
                                          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

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