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    Replaced LED. Lights on its own but not in the strip

    I had 1 LED out on a Bauhn ATVS58-0516.

    I had some spares so I took one of an old strip (after making sure it worked) and took the bad one off the strip.

    I then put the replacement one on the strip.

    Now all the original lights light up (same as before) but the new one doesnt.

    I put the backlight tester on each side of the replacement and it lights up no problem.

    What am I doing wrong? This is the first time I have tried this procedure and I thought it went well.

    #2
    Re: Replaced LED. Lights on its own but not in the strip

    Sounds like the LED got hot during replacement or the solder didn't take.
    They call me......."threadkiller"

    Comment


      #3
      Re: Replaced LED. Lights on its own but not in the strip

      I have tried it again and same result.

      Im thinking maybe the pad was damaged when the original led blew?

      The pic is the pad. Not sure how I would fix that?

      Or does it just need some solder on the bigger part of the pad? Looks like there isnt any on it
      Attached Files
      Last edited by RooTV; 06-02-2020, 08:08 PM.

      Comment


        #4
        Re: Replaced LED. Lights on its own but not in the strip

        I tried putting some solder on the pad but made no difference so I assume that the pad is damaged?

        But is it fixable. Thas the question.

        Comment


          #5
          Re: Replaced LED. Lights on its own but not in the strip

          I have tried it again and same result.

          Im thinking maybe the pad was damaged when the original led blew?

          The pic is the pad. Not sure how I would fix that?

          Added photo of led strip with new led on it (not working)
          Attached Files
          Last edited by RooTV; 06-02-2020, 09:00 PM.

          Comment


            #6
            Re: Replaced LED. Lights on its own but not in the strip

            Originally posted by RooTV View Post
            I had 1 LED out on a Bauhn ATVS58-0516.

            I had some spares so I took one of an old strip (after making sure it worked) and took the bad one off the strip.

            I then put the replacement one on the strip.

            Now all the original lights light up (same as before) but the new one doesnt.

            I put the backlight tester on each side of the replacement and it lights up no problem.

            What am I doing wrong? This is the first time I have tried this procedure and I thought it went well.
            So the LED strip with the replacement LED installed, all the LED's on that strip light up but not the replacement LED? Since the LEDs are connected in series so for the strip to light up but the replacement does not t hen the polarity of the replacement is back ward so the current flow through the protection Zener diode of the replacement LED instead, if you shorted out the pad then the LED should not light up when tested with the tester. What is the Vf shown on your LED tester? 3v or 6v?
            Last edited by budm; 06-02-2020, 09:59 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


              #7
              Re: Replaced LED. Lights on its own but not in the strip

              Maybe use a resistor to bypass that led, hopefully one led off won't be too noticeable.

              Comment


                #8
                Re: Replaced LED. Lights on its own but not in the strip

                1. The LEDs can be 3 or 6v
                2. The LEDs can be with + or - on the big pad
                3. The LEDs are replaced by heating the strip on the back, not on the LED.

                Comment


                  #9
                  Re: Replaced LED. Lights on its own but not in the strip

                  Originally posted by yokoono View Post
                  1. The LEDs can be 3 or 6v
                  I thought they were both 3v. but Im not 100% sure.

                  Does either of these pictures tell which it is? 3v or 6v? This is the original strip.

                  And the donor strip is the 3rd and 4th pic.

                  Please let me know how you tell what voltage they are, if any of these pics tells you.

                  Im very much a newbie but very keen to learn and appreciate any help I get
                  Attached Files
                  Last edited by RooTV; 06-02-2020, 10:40 PM.

                  Comment


                    #10
                    Re: Replaced LED. Lights on its own but not in the strip

                    Originally posted by yokoono View Post
                    2. The LEDs can be with + or - on the big pad
                    I turned the LED around on the pad and then none of the LED's on the strip would light up, so I assume that was on the incorrect way and was affecting the others?

                    Comment


                      #11
                      Re: Replaced LED. Lights on its own but not in the strip

                      Originally posted by budm View Post
                      So the LED strip with the replacement LED installed, all the LED's on that strip light up but not the replacement LED? Since the LEDs are connected in series so for the strip to light up but the replacement does not t hen the polarity of the replacement is back ward
                      I have tried 4 different donor LED's so far backwards and forwards, but havent had any luck yet.
                      What is the Vf shown on your LED tester? 3v or 6v?
                      2.8v on both the donor LED and original LED

                      Comment


                        #12
                        Re: Replaced LED. Lights on its own but not in the strip

                        So it is 3V LED then.
                        How about my question?
                        "So the LED strip with the replacement LED installed, all the LED's on that strip light up but not the replacement LED? "
                        Last edited by budm; 06-02-2020, 10:53 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


                          #13
                          Re: Replaced LED. Lights on its own but not in the strip

                          Originally posted by budm View Post
                          So the LED strip with the replacement LED installed, all the LED's on that strip light up but not the replacement LED?
                          Yes

                          Since the LEDs are connected in series so for the strip to light up but the replacement does not t hen the polarity of the replacement is back ward so the current flow through the protection Zener diode of the replacement LED instead
                          I have tried the LED in both orientations on the pad. In the first way the strip lights up but not the donor, in the other orientation, no led's light up.

                          if you shorted out the pad then the LED should not light up when tested with the tester.
                          I assume this is what I have done. Is there any fix for this or do I just order another strip?
                          Last edited by RooTV; 06-02-2020, 11:01 PM.

                          Comment


                            #14
                            Re: Replaced LED. Lights on its own but not in the strip

                            Originally posted by RooTV View Post
                            Yes


                            I have tried the LED in both orientations on the pad. In the first way the strip lights up but not the donor, in the other orientation, no led's light up.


                            I assume this is what I have done. Is there any fix for this or do I just order another strip?
                            Well if the other LEDs are lit up but not the replacement that means the replacement LED connection is bypassed somehow, otherwise the other LEDs will not be on, it is series connected circuit.
                            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


                              #15
                              Re: Replaced LED. Lights on its own but not in the strip

                              If the led connection is bypassed, does that mean the tv will work when I put it back together again?

                              Or I need to get another strip to replace it

                              sorry Im a bit confused

                              Comment


                                #16
                                Re: Replaced LED. Lights on its own but not in the strip

                                Well, that is what is confusing to me that the replacement LED does not light up but the other LEDs are lit up OK on that LED strip, but you said the replace lights up when using the LED tester so it it means the pads of the replacement are not shorted (bypassed), that is what not making sense to me. You can bypass 1 LED without triggering the protection circuit but you may see dark spot on the screen when you have light shaded scene.
                                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


                                  #17
                                  Re: Replaced LED. Lights on its own but not in the strip

                                  Im sorry I may have phrased it badly and confused you.

                                  When I say that the donor led lights up, I mean that when I put the led tester directly on the led, not the pad.

                                  Comment


                                    #18
                                    Re: Replaced LED. Lights on its own but not in the strip

                                    Im not sure the tv will work without the led anyway as that is what I think was the issue with the tv not working in the first place. (well I was hoping it was anyway).

                                    The tv was given to me because it was not showing a picture, but I could see one using a torch, which Im told normally means a backlight issue.

                                    I will put the tv back together again now as I dont have the room to leave it dismantled while I wait for parts, but Im not expecting it to work.

                                    I was really hoping to get the led fixed today as this thing is a real pain in the ass to pull apart and reassemble and everytime I have to do it means more chance of me doing something nasty to the screen
                                    Last edited by RooTV; 06-02-2020, 11:34 PM.

                                    Comment


                                      #19
                                      Re: Replaced LED. Lights on its own but not in the strip

                                      When the LED goes open circuit, as per your original problem, the protection circuit will kick in, if too many LEDs are bypassed the protection will also kick in, but bypassing one LED may not trigger the protection circuit.
                                      It is beat to replace all the strips and the turn down the backlights level on all input mode and do not set them to other backlights mode, I.E. Dynamic, etc.
                                      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: Replaced LED. Lights on its own but not in the strip

                                        If I could get all the strips - they are bloody hard to find although I havent checked alib express yet - I would replace them all.

                                        I have to determine if its the only problem on the tv first, otherwise it isnt feasible.

                                        I do appreciate all your help and thank you very much.

                                        Comment

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