LG 42" LCD 42LD550 will not turn on or turns itself off/on

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  • stolen
    New Member
    • Aug 2013
    • 5
    • USA

    #1

    LG 42" LCD 42LD550 will not turn on or turns itself off/on

    Hi. I want to repair this issue myself. If i cannot, then I will be happy to buy a new TV. Not. LOL...

    Can any of you awesome techs please help? I need to know what to do, what parts to buy, and instruction on how to repair?

    Problem:
    The TV will not turn on, or if it comes on, it will turn off and then try to turn itself back on and off. I might get the LG splash screen for a second, then black again. The red light on the bottom does not turn blue at all like it is supposed to.

    This tv is 2 years old. I did the normal troubleshooting like hard reset, unplugged and waited, plugged directly into wall socket, checked remote, etc.

    From my research online, it appears this is a common issue with this model.

    From lg.com answers: "It is difficult to determine the cause of this symptom, but it seems like there could be a failing of the power supply or main board."

    and one more answer from the LG board:

    The problem could range from a thermal or vibration intermittent solder connection on the TV's main board or a poorly sheilded device connected to the TV (I have none other than the uVerse box). You may need to take the TV to an authorized servicer to have more elaborate testing performed in the shop, such as thermal and applied voltage stress testing. One other possibility might be fluctuating line voltage or arcing in the wall outlet that provides power to the TV (this apartment is brand new, unlikely to have wall outlet power issues). It could be that there is a problem that the TV's internal power supply protection system is sensing, and it is shutting the TV down to protect it, or that the shut-down circuit is working overtime. Again, contact an authorized servicer.

    Any recommendations and help would be most appreciated. I miss my tv.

    Thanks all.
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

    It is most likely to be a main board problem - corrupted firmware or EEPROM data.

    Do you have a digital multimeter, and digital camera?
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • stolen
      New Member
      • Aug 2013
      • 5
      • USA

      #3
      Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

      Hi. Thank you. I agree i think the issue is some internal problem.

      Yes, I do have a digital camera.

      No, do not have a digital multimeter. I can buy one.

      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

        If you can get hold of a digital meter, the outputs of the power supply can be checked to rule it out.
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

        Comment

        • stolen
          New Member
          • Aug 2013
          • 5
          • USA

          #5
          Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

          ok i will either borrow one tomorrow from work, we have labs there or go pick one up. Just to make sure I understand, I will unplug the power supply and test the plug there on the back of the TV? Then I can post the results here If i can get one today, I will let you know, and we'll go from there. thank you...will get back to you.

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

            You'd be testing the output voltages with the power supply switched on and connected to all boards, for initial testing.
            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

            Comment

            • stolen
              New Member
              • Aug 2013
              • 5
              • USA

              #7
              Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

              Hi. thanks again. I may come back here after I get the meter. This is a learning process for me. I do not know where to place the voltage meter or the tester. You may have to guide me. I may have a question about the meter, but let me get the meter first. Sorry, true novice here. but I would rather learn how to do it myself than get someone else.

              thank you again, really appreciate your help.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                Just to be safe for beginner, I would plug what you are working on into GFI outlet, or make one of this.
                http://s807.photobucket.com/user/bud...tml?sort=3&o=7
                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

                • g.pol
                  Member
                  • Dec 2012
                  • 17
                  • greece

                  #9
                  Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                  Hi
                  Have problems with the power supply.
                  Burn safety!
                  A quick test I did locate a zener shorted the ZD503.
                  I do attempt to find the service manual of the power supply and can not find anything!
                  have no idea?
                  The code board is PCB: EAX61124201/15 REV 1.2
                  Thank you

                  edit:
                  hi
                  returns on the problem.
                  change the STRW6053N and the zener 5.1 volt.
                  not burn safety but now, than are measured at the terminal (CONNECTOR) board I only have 3.5 volts.
                  12, and 24 volts I have not!

                  Comment

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #10
                    Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                    Location of the zener - if it is on VCC pin of the IC, 5.1V is unusually low.
                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                    Comment

                    • g.pol
                      Member
                      • Dec 2012
                      • 17
                      • greece

                      #11
                      Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                      Originally posted by tom66
                      Location of the zener - if it is on VCC pin of the IC, 5.1V is unusually low.
                      hello.
                      measurements on capacitors CONNECTOR exit, and see that I have measurements kanonika.gia example measures 12 and 20 volts.
                      c205=3,5v
                      c218=13,4v
                      c210=20v
                      c220=20v
                      c215=3,5v
                      c208=?
                      c217=?
                      c219+13,4v
                      c204=3,5v
                      But CONNECTOR not, count only the 3.5 volts.

                      I suspect that is the Q203(FDD5614P) shows up in photo
                      What do you think?

                      And one last thing
                      Domestic to make the measurements,
                      The PCB of the power supply must I connected with the main board of the television, or does not matter?
                      Attached Files
                      Last edited by g.pol; 03-12-2014, 04:43 AM.

                      Comment

                      • HellasTechn1
                        Senior Member
                        • Sep 2015
                        • 176
                        • Greece

                        #12
                        Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                        Have we found the solution for this after all ? Thanks.

                        Comment

                        • HellasTechn1
                          Senior Member
                          • Sep 2015
                          • 176
                          • Greece

                          #13
                          Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                          The one i am working on when turned on the red led will blink at slow rate and nothing else happens.

                          All voltages are ok appart from the 3.5V that appear to be 3.3V.
                          I suspect mainboard problem but again 3.3 is low...

                          Comment

                          • dskall
                            Badcaps Legend
                            • Oct 2016
                            • 2905
                            • usa

                            #14
                            Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                            Originally posted by stolen
                            Hi. thanks again. I may come back here after I get the meter. This is a learning process for me. I do not know where to place the voltage meter or the tester. You may have to guide me. I may have a question about the meter, but let me get the meter first. Sorry, true novice here. but I would rather learn how to do it myself than get someone else.

                            thank you again, really appreciate your help.
                            You may want to watch some YouTube videos while you are waiting for meter. https://www.youtube.com/watch?v=ZBbgiBU96mM Lots out there.

                            I was commenting to stolen the op
                            Last edited by dskall; 02-17-2017, 03:07 PM.
                            I assume no responsibility for any stupid suggestions I might post.

                            Comment

                            • HellasTechn1
                              Senior Member
                              • Sep 2015
                              • 176
                              • Greece

                              #15
                              Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                              It wasnt me waiting for the meter but ok.

                              I do hear some weird noise from the mainboard. any ideas ? could the 3.3V instead of 3.5 be the problem ?

                              Comment

                              • budm
                                Badcaps Legend
                                • Feb 2010
                                • 40746
                                • USA

                                #16
                                Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                                Originally posted by HellasTechn1
                                It wasnt me waiting for the meter but ok.

                                I do hear some weird noise from the mainboard. any ideas ? could the 3.3V instead of 3.5 be the problem ?
                                How about uploading good clear pictures of the back side of the TV showing all the boards so we can see what we are dealing with?
                                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

                                • HellasTechn1
                                  Senior Member
                                  • Sep 2015
                                  • 176
                                  • Greece

                                  #17
                                  Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                                  I will tomorrow. Thanks.

                                  Comment

                                  • skywriter
                                    New Member
                                    • Feb 2017
                                    • 5
                                    • Norway

                                    #18
                                    Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                                    Hi,

                                    I am a new user thank you for accepting me as member in this forum. I have the same problem reported 4 years ago in this post.

                                    TV Model: LG 32ld450-za.bekwLJP
                                    Power board EAX611242011_15 (LGP32-10LF)

                                    My TV started to be ON OFF intermittently with its power indicator pulsing red. After some time the screen was always OFF although the power indicator still pulsing.

                                    I removed the power board from the panel and probed the connector pins to the main board. I can measure 3.5V on pins 9 10 11 12 both nothing on 2 3 4 (expected 20V) nor 19 21 (expected 12V). Also no voltage on pin 1 PWR_ON. I am not sure if I should have left the power board connected to main board for the measurement? Do you have any suggestion to move forward on the investigation?

                                    I appreciate your help!
                                    Kind regards
                                    Massimo

                                    Comment

                                    • ReeceyBurger123
                                      Never Give Up !
                                      • May 2014
                                      • 7325
                                      • Britain

                                      #19
                                      Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                                      Mainboard bga issue. Replace mainboard.
                                      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                                      https://www.facebook.com/Telford-Tel...7894576335359/

                                      Comment

                                      • Billy03
                                        New Member
                                        • May 2018
                                        • 2
                                        • Germany

                                        #20
                                        Re: LG 42" LCD 42LD550 will not turn on or turns itself off/on

                                        Had the same problem with an LG 32ld750 TV.

                                        The zener is not shorted, it has a 0.1 Ohm Resistor in parallel. Really!
                                        Changed the STRW6053N anyway and the TV is working again!



                                        Originally posted by g.pol
                                        Hi
                                        Have problems with the power supply.
                                        Burn safety!
                                        A quick test I did locate a zener shorted the ZD503.
                                        I do attempt to find the service manual of the power supply and can not find anything!
                                        have no idea?
                                        The code board is PCB: EAX61124201/15 REV 1.2
                                        Thank you

                                        edit:
                                        hi
                                        returns on the problem.
                                        change the STRW6053N and the zener 5.1 volt.
                                        not burn safety but now, than are measured at the terminal (CONNECTOR) board I only have 3.5 volts.
                                        12, and 24 volts I have not!

                                        Comment

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