Announcement

Collapse
No announcement yet.

Lg32lb561v power supply(i think?) problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Lg32lb561v power supply(i think?) problem

    Hey guys! I've been trying to fix this tv i had laying around for some time, was wondering if you could help me find the problem because i ran out of knowledge, i'm just a self taught repair wannabe so i apologise in advance for my lack of knowledge

    So, one day this tv stopped turning on, only flashed the red light once and then stopping, i took it apart and looked at the power supply, noticed two blown capacitors (the red circled ones) and replaced them, soldering was a bit wonky because one was longer but its the right farad and voltage, still nothing, no turning on no pic.

    Then i replaced every capacitor i could get my hands on, nothing.

    I tested fuses and diodes (well i think i did, i'm not so sure of my work ) they seemed all fine.

    Searched the schematics of the board EAX65391401 3.0 and started trying to understand something.

    I measured the voltages at the connector that goes in the logic board, 3,5v 24v and 12v are there and perfectly fine

    Then i measured the backlight current that should be 117v and found that it was putting out approx 140v

    Oh and today i noticed a really low crackling noise (bzzzzzzzz) coming from the bottom right of the board, like an electric dispersion but could not find where it was

    Tl;dr Tv didn't turn on, only one red blink, Replaced bad caps on powersupply, still nothing, backlight line puts out 140v instead of 117v, crackling noise on bottom right of the board, i have no idea of what i'm doing

    Sorry for the long post, i tried to put as many info as possible, tried to follow the guides sticked at the top but nothing,

    Am i better off buying a new board or is there hope?

    Thanks a lot
    Attached Files
    Last edited by gtanick; 09-18-2018, 11:40 AM.

    #2
    Re: Lg32lb561v power supply(i think?) problem

    What made you think those caps were blown? they usually don't give a problem, Usually a high led voltage indicates an open led string in the panel.
    Last edited by R_J; 09-18-2018, 11:57 AM.

    Comment


      #3
      Re: Lg32lb561v power supply(i think?) problem

      Originally posted by R_J View Post
      What made you think those caps were blown? they usually don't give a problem, Usually a high led voltage indicates an open led string in the panel.
      Hi, thanks for the answer!

      I still keep those capacitors because i never saw something like that, i attached a pic of those

      So is it the led stripes in the panel's fault? i tried measuring while unplugging the connector and it still gives out 140v like if the 117v line broke somewhere on the power supply

      If i may ask you a question, would the tv turn on without backlight if i unplugged only that and everything else was fine?

      Thanks again!

      Edit: i attached another pic to show where i got the 140v (117v) measurement, is that the right spot?

      Edit2:Now measuring from the + and - on the connector gives out 63-64v while putting - on the big screw in the bottom left corner of the board still gives 140v, this tv confuses me lol
      Attached Files
      Last edited by gtanick; 09-18-2018, 12:30 PM.

      Comment


        #4
        Re: Lg32lb561v power supply(i think?) problem

        Those caps are definitely bad. How many wires go to the leds? If it is just two and you measure 64v I would think the backlights should be on
        If you measure the voltage from the led (-) to ground what do you get? they usually supply full voltage to the (+) side and control the (-) side of the led's.
        I still think its bad led string.

        Comment


          #5
          Re: Lg32lb561v power supply(i think?) problem

          Originally posted by R_J View Post
          Those caps are definitely bad. How many wires go to the leds? If it is just two and you measure 64v I would think the backlights should be on
          If you measure the voltage from the led (-) to ground what do you get? they usually supply full voltage to the (+) side and control the (-) side of the led's.
          I still think its bad led string.
          Its 2 wires to the leds, measuring those 2 wires gives out 80v when leds are connected and 64v when they are not

          Led(-) to ground gives 0.00 and led(+) to ground still gives 140v

          Thanks again for your time

          Comment


            #6
            Re: Lg32lb561v power supply(i think?) problem

            I would still suspect bad led string, Here is a video that might be of some help https://www.youtube.com/watch?v=peG1cIpXqeg

            Comment


              #7
              Re: Lg32lb561v power supply(i think?) problem

              Originally posted by R_J View Post
              I would still suspect bad led string, Here is a video that might be of some help https://www.youtube.com/watch?v=peG1cIpXqeg
              I will check the led strings, thanks again

              Comment


                #8
                Re: Lg32lb561v power supply(i think?) problem

                It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.
                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


                  #9
                  Re: Lg32lb561v power supply(i think?) problem

                  Originally posted by budm: It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.
                  +1k
                  Last edited by Andrew F. Ali; 09-18-2018, 03:36 PM.

                  Comment


                    #10
                    Re: Lg32lb561v power supply(i think?) problem

                    Originally posted by budm View Post
                    It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.
                    I'll check it as soon as i come home

                    So if one of the leds is bad or there is an opening in the circuit of the leds the whole tv wont turn on at all right?

                    So i can be sure about the power supply right? If the leds are the problem, changing them would bring the tv back ?

                    i'm sorry i'm spitting out questions like a machine i'm just interested in how these circuits work

                    Comment


                      #11
                      Re: Lg32lb561v power supply(i think?) problem

                      Is your LCD panel sticker: NC320DXN-VSBP1? You need to match the strips to the LCD panel.
                      The LED strips look something like this: https://www.ebay.com/i/283120816368?chn=ps
                      The LED's are connected in series so if one go open circuit then you will not get any lights.
                      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


                        #12
                        Re: Lg32lb561v power supply(i think?) problem

                        Originally posted by budm View Post
                        Is your LCD panel sticker: NC320DXN-VSBP1? You need to match the strips to the LCD panel.
                        The LED strips look something like this: https://www.ebay.com/i/283120816368?chn=ps
                        The LED's are connected in series so if one go open circuit then you will not get any lights.
                        Thanks for the answer again

                        I think i expressed myself wrong english is not my first language, sorry , i meant if there's an opening in the leds circuit, should i get sound/tv working and no lights or no sign of life at all? Because looking at some videos regarding this problem they all seem to have sound and tvs working without backlight ofc but mine isnt putting out any sound nor it does turn on
                        When i plug it the red light blinks and dims to off, pressing the button does not do anything

                        Comment


                          #13
                          Re: Lg32lb561v power supply(i think?) problem

                          Quick update, YOU GUYS ARE AWESOME!!!
                          It was the led stripes, i found a couple of broken ones, just tried to bridge them to check if it would work and it did !!!
                          Thanks a lot guys, you understood in a blink of an eye what it was, i hope i can get to that level one day
                          Thanks again !!!

                          Comment


                            #14
                            Re: Lg32lb561v power supply(i think?) problem

                            So are you going to purchase new strips and change them out? I would recommend changing all the strips as you don't want to go back in there as there is the chance of breaking the glass screen and destroying your TV.

                            Comment


                              #15
                              Re: Lg32lb561v power supply(i think?) problem

                              Originally posted by Andrew F. Ali View Post
                              So are you going to purchase new strips and change them out? I would recommend changing all the strips as you don't want to go back in there as there is the chance of breaking the glass screen and destroying your TV.
                              Yeah, i already ordered them, i just tested without fixing everything back in place, when they'll arrive i'll swap them Thanks again !

                              Comment


                                #16
                                Re: Lg32lb561v power supply(i think?) problem

                                Don't forget to give us a feedback.

                                Comment


                                  #17
                                  Re: Lg32lb561v power supply(i think?) problem

                                  Originally posted by Andrew F. Ali View Post
                                  Don't forget to give us a feedback.
                                  New stripes arrived, the tv looks as good as new! Cheers to you guys, thanks again for the massive help

                                  Comment


                                    #18
                                    Re: Lg32lb561v power supply(i think?) problem

                                    Applause...You did well...thanks for the feedback.

                                    Comment


                                      #19
                                      Re: Lg32lb561v power supply(i think?) problem

                                      Make sure to turn down the backlights level to as low as you can to extend the life of the LED's.
                                      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


                                        #20
                                        Re: Lg32lb561v power supply(i think?) problem

                                        Originally posted by Andrew F. Ali View Post
                                        Applause...You did well...thanks for the feedback.
                                        Thanks to you guys again
                                        Originally posted by budm View Post
                                        Make sure to turn down the backlights level to as low as you can to extend the life of the LED's.
                                        Will definitely do, thank you !

                                        Comment

                                        Working...
                                        X