Motherboard: NEW90 L21 No LED Backlight on Display

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  • Reech
    Member
    • Sep 2012
    • 21
    • United States

    #1

    Motherboard: NEW90 L21 No LED Backlight on Display

    I can faintly see image on the display with flashlight but screen has no brightness at all. Laptop was dropped; replaced the power jack and LED display cable. Both were damaged and the left hinge was snapped off and flopping around. The LED cable must have shorted something since the display was working prior to the repairs.
    The 2 fuses on back of the LED display check good.
    I could not locate any other fuses on the motherboard.
  • selldoor
    Slow Learner
    • Dec 2010
    • 7870

    #2
    Re: Motherboard: NEW90 L21 No LED Backlight on Display

    Double post _ double post
    Please upload pictures using attachment function when ask for help on the repair
    http://www.badcaps.net/forum/showthread.php?t=39740

    Comment

    • dj_ricoh
      Badcaps Legend
      • Jan 2013
      • 2073
      • uk

      #3
      Re: Motherboard: NEW90 L21 No LED Backlight on Display

      first find the schematic
      2nd what voltage you got on the ribbon connector from lcd
      Just cook it! It's already broken.

      Comment

      • Reech
        Member
        • Sep 2012
        • 21
        • United States

        #4
        Re: Motherboard: NEW90 L21 No LED Backlight on Display

        Sorry for the double post but I couldn't find any answers to this issue.
        Can't find a schematic. I'll take some pics of the mobo, top and bottom.
        Thanks

        Comment

        • khaahk
          Badcaps Veteran
          • Dec 2013
          • 756
          • Estonia

          #5
          Re: Motherboard: NEW90 L21 No LED Backlight on Display

          become friends with google, it took me 30 seconds.
          https://cdn.badcaps-static.com/pdfs/...efbeaa87f2.pdf

          Comment

          • Reech
            Member
            • Sep 2012
            • 21
            • United States

            #6
            Re: Motherboard: NEW90 L21 No LED Backlight on Display

            Wow the schematic is great! Wish I could decipher where the fuses would be.
            I am attaching to pics of the mobo hopefully someone could lead me to the fuses. Thanks
            Attached Files

            Comment

            • Reech
              Member
              • Sep 2012
              • 21
              • United States

              #7
              Re: Motherboard: NEW90 L21 No LED Backlight on Display

              Sorry, here's other side
              Attached Files

              Comment

              • khaahk
                Badcaps Veteran
                • Dec 2013
                • 756
                • Estonia

                #8
                Re: Motherboard: NEW90 L21 No LED Backlight on Display

                first ones to check - L12, L13

                Comment

                • dj_ricoh
                  Badcaps Legend
                  • Jan 2013
                  • 2073
                  • uk

                  #9
                  Re: Motherboard: NEW90 L21 No LED Backlight on Display

                  that is a normal led screen.
                  the only difference in this led screen and a ccfl its the tube.
                  yours got a led stripe.
                  find a smash and test like that.
                  don`t open the mobo and start poking around
                  Just cook it! It's already broken.

                  Comment

                  • MDY
                    Senior Member
                    • Jan 2014
                    • 75
                    • Spain

                    #10
                    Re: Motherboard: NEW90 L21 No LED Backlight on Display

                    Did you check KBC? It send sime signals to LED screen...

                    Comment

                    • Reech
                      Member
                      • Sep 2012
                      • 21
                      • United States

                      #11
                      Re: Motherboard: NEW90 L21 No LED Backlight on Display

                      Thank you to all for the replies, much appreciated!
                      kkaahk, I will check L12, L13 (are they top or bottom of board?) Any directions appreciated.
                      Dj Ricoh, what do you mean find a smash and work like that?
                      MDY, are you saying KBC (key board connector?)

                      Comment

                      • dj_ricoh
                        Badcaps Legend
                        • Jan 2013
                        • 2073
                        • uk

                        #12
                        Re: Motherboard: NEW90 L21 No LED Backlight on Display

                        Test the mobo with another screen.
                        Just cook it! It's already broken.

                        Comment

                        • Reech
                          Member
                          • Sep 2012
                          • 21
                          • United States

                          #13
                          Re: Motherboard: NEW90 L21 No LED Backlight on Display

                          I don't have another screen to test. I am also not that high a level as you all seem to be at re: testing and probing these tiny components.
                          Not sure where to test the voltages going to the screen.
                          There must be something either the led backlight or voltages to it or a fuse along the way that was shorted at some point. As I said it boots great, you just can't see anything since the backlight is not functioning.
                          If it's the mobo it's just not worth the $$$'s at this point.
                          Thanks to all for your great replies! Much appreciated!!!!

                          Comment

                          • Reech
                            Member
                            • Sep 2012
                            • 21
                            • United States

                            #14
                            Re: Motherboard: NEW90 L21 No LED Backlight on Display

                            Khaahk, I checked - L12, L13 and they check for continuity.
                            Are the L s the fuses?
                            Thanks

                            Comment

                            • selldoor
                              Slow Learner
                              • Dec 2010
                              • 7870

                              #15
                              Re: Motherboard: NEW90 L21 No LED Backlight on Display

                              Can you stop one of these threads running - looking through them both is very time consuming.
                              Please upload pictures using attachment function when ask for help on the repair
                              http://www.badcaps.net/forum/showthread.php?t=39740

                              Comment

                              • khaahk
                                Badcaps Veteran
                                • Dec 2013
                                • 756
                                • Estonia

                                #16
                                Re: Motherboard: NEW90 L21 No LED Backlight on Display

                                The L-s should be also working as fuses, they are ok. Power on the mainboard and do some careful voltage measurements (not to touch other pins while measuring or you might end up with dead mainboard) with the panel attached and power turned on.
                                Start counting the pins from the white triangle (right to left).
                                1-3 - should be adapter voltage
                                4-6 - should be 3.3V (which you have or else you would not see any picture on panel)
                                7 - should be also 3.3V (on stby also)
                                8 - maybe 1.5-3V (depending on screen brightness setting)
                                9 - should be above 2V
                                12 - not sure above 2V maybe digital signal, here should some info about brightness also

                                Write back the results, lets see then.
                                You also might have broken backlight on panel...
                                Last edited by khaahk; 01-26-2014, 03:34 PM.

                                Comment

                                • MDY
                                  Senior Member
                                  • Jan 2014
                                  • 75
                                  • Spain

                                  #17
                                  Re: Motherboard: NEW90 L21 No LED Backlight on Display

                                  I have the same problem. Can you post that tension you have on screen conector on pin 1,2,3,,36,38,39,40?

                                  Comment

                                  • Reech
                                    Member
                                    • Sep 2012
                                    • 21
                                    • United States

                                    #18
                                    Re: Motherboard: NEW90 L21 No LED Backlight on Display

                                    selldoor, I just spent `15mins searching on how to stop/delete a thread and cannot find anything. I will try again later, Thanks

                                    Comment

                                    • selldoor
                                      Slow Learner
                                      • Dec 2010
                                      • 7870

                                      #19
                                      Re: Motherboard: NEW90 L21 No LED Backlight on Display

                                      You Cant !! What you can do is put a post on saying please put
                                      any future replies to ...... and put the link in for the other thread.

                                      If you want to make a good job of it copy and paste the questions and answers
                                      from the thread you are stopping to the thread you are keeping.
                                      Please upload pictures using attachment function when ask for help on the repair
                                      http://www.badcaps.net/forum/showthread.php?t=39740

                                      Comment

                                      • Reech
                                        Member
                                        • Sep 2012
                                        • 21
                                        • United States

                                        #20
                                        Re: Motherboard: NEW90 L21 No LED Backlight on Display

                                        Closing this thread, please post to:
                                        https://www.badcaps.net/forum/showthread.php?t=34610

                                        Comment

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