samsung ue55nu7021k backlights working but blank screen

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  • Chrissygizmo
    Senior Member
    • Mar 2021
    • 108
    • United Kingdom

    #1

    samsung ue55nu7021k backlights working but blank screen

    I have a Samsung ue55nu7021k that has working backlights but has a dark blank screen..

    I've tried a couple of different boards from a friend without success, however, one of the boards produced the Samsung Smart logo on the screen so I'm guessing it's the main board that's at fault, is there anything I could try to repair the board or is it a case of buying a new one ?

    Thanks in advance
    Attached Files
  • brucetv
    Badcaps Veteran
    • May 2015
    • 281
    • united states

    #2
    Re: samsung ue55nu7021k backlights working but blank screen

    If you got the Samsung logo to come up does it go any farther after that or just freeze at the logo?

    Comment

    • Davi.p
      Hobbist Tech
      • Sep 2009
      • 4317
      • Italy - Milan

      #3
      Re: samsung ue55nu7021k backlights working but blank screen

      Are you female? Do you hear sound? if you hear maybe there's a fault in the tcon section of your mainboard , but i don't know if you are familiar with electronic inspections..

      Comment

      • Yoda79
        Senior Member
        • Dec 2021
        • 56
        • United Kingdom

        #4
        Re: samsung ue55nu7021k backlights working but blank screen

        Hi, wondering if anyone can help. I have the same model TV, Samsung UE55NU7021KXXXU. The TV was running fine but then all of a sudden started encountering problems. The sound would work, the remote wouldn't work! Now the TV turns on, although very slow boot up now but when it does it comes with the Samsung Logo then onto a screen showing No Signal. I try pressing Source on the remote but nothing happens. The home button also doesn't work, so I can not get any of the smart apps up. Also, everything is running very slowly.

        However, if I click the actual button at the bottom of the screen and bring up the menu, then I get goto source and manage to select one of the HDMI's and get a signal. However while the picture shows, i keep getting the turning circle (as per the attached photo of the BBC news - you can just see the turning circle in the middle of the screen) and it says it's adjusting the picture. Also there is no sound. Under the settings, the picture test shows fine but sound test fails to work. I should add that this is temperamental as well as sometimes also does not work (the button at bottom of screen)

        Any ideas on how to fix? I've added some photos of the screen and model to help.

        Also, some times when I boot, instead of the normal commands, I get coding on the titles (as per photo)
        Attached Files

        Comment

        • dskall
          Badcaps Legend
          • Oct 2016
          • 2905
          • usa

          #5
          Re: samsung ue55nu7021k backlights working but blank screen

          Sounds like maybe a firmware problem. Does temperature affect problem?
          I assume no responsibility for any stupid suggestions I might post.

          Comment

          • vinceroger69
            Badcaps Legend
            • Mar 2012
            • 6714
            • uk

            #6
            Re: samsung ue55nu7021k backlights working but blank screen

            maybe a faulty nand ic/firmware

            Comment

            • Yoda79
              Senior Member
              • Dec 2021
              • 56
              • United Kingdom

              #7
              Re: samsung ue55nu7021k backlights working but blank screen

              Hi, thanks for your replies.

              So I don't believe temperature affects it as starting to go wrong in the same room its been in for the past 2 years!

              I try and do an update to the firmware but it just crashes and doesn't do anything and reverts back to the same screen.

              Sorry what do you mean by a faulty nand IC?

              hank you for your help. Its only like 2.5 years old!

              Comment

              • Yoda79
                Senior Member
                • Dec 2021
                • 56
                • United Kingdom

                #8
                Re: samsung ue55nu7021k backlights working but blank screen

                Sorry but is there a way that you can get an email when someone replies?

                Comment

                • vinceroger69
                  Badcaps Legend
                  • Mar 2012
                  • 6714
                  • uk

                  #9
                  Re: samsung ue55nu7021k backlights working but blank screen

                  Originally posted by Yoda79
                  Hi, thanks for your replies.

                  So I don't believe temperature affects it as starting to go wrong in the same room its been in for the past 2 years!

                  I try and do an update to the firmware but it just crashes and doesn't do anything and reverts back to the same screen.

                  Sorry what do you mean by a faulty nand IC?

                  hank you for your help. Its only like 2.5 years old!
                  Nand ic or eeprom ic is the chip that stores the firmware etc on samsungs quite common they go faulty.
                  Have you got a good clear picture of the mainboard so that we can see all the numbers on it.

                  Comment

                  • lotas
                    Badcaps Legend
                    • Jan 2016
                    • 4578
                    • Russia

                    #10
                    Re: samsung ue55nu7021k backlights working but blank screen

                    The memory may be full, you can try to do a "factory reset" through the service menu.

                    Comment

                    • vinceroger69
                      Badcaps Legend
                      • Mar 2012
                      • 6714
                      • uk

                      #11
                      Re: samsung ue55nu7021k backlights working but blank screen

                      Originally posted by lotas
                      The memory may be full, you can try to do a "factory reset" through the service menu.
                      lotas what type of memory ics do these use nand or eeprom ive not worked on one of these sets yet

                      Comment

                      • lotas
                        Badcaps Legend
                        • Jan 2016
                        • 4578
                        • Russia

                        #12
                        Re: samsung ue55nu7021k backlights working but blank screen

                        EMMc flash has been used in new models for a long time.
                        This model also has SPI Flash and EEPROM, but the software is in EMMc.
                        Last edited by lotas; 12-06-2021, 05:48 AM.

                        Comment

                        • vinceroger69
                          Badcaps Legend
                          • Mar 2012
                          • 6714
                          • uk

                          #13
                          Re: samsung ue55nu7021k backlights working but blank screen

                          Originally posted by lotas
                          EMMc flash has been used in new models for a long time.
                          This model also has SPI Flash and EEPROM, but the software is in EMMc.
                          Thankyou

                          Comment

                          • Yoda79
                            Senior Member
                            • Dec 2021
                            • 56
                            • United Kingdom

                            #14
                            Re: samsung ue55nu7021k backlights working but blank screen

                            Originally posted by lotas
                            The memory may be full, you can try to do a "factory reset" through the service menu.
                            I know there was a memory issue with this tv as I could never install any more apps, did see some posts about this too. Bizarre as surely you would put a TV out there with sufficient memory on it!On the factory rest is the the "reset" under support/self diagnosis as per photo?

                            Thank you for your help and time!
                            Attached Files

                            Comment

                            • Yoda79
                              Senior Member
                              • Dec 2021
                              • 56
                              • United Kingdom

                              #15
                              Re: samsung ue55nu7021k backlights working but blank screen

                              Originally posted by vinceroger69
                              Nand ic or eeprom ic is the chip that stores the firmware etc on samsungs quite common they go faulty.
                              Have you got a good clear picture of the mainboard so that we can see all the numbers on it.
                              I have opened it yet but let me give this a go tonight and I'll get a clear picture. I'm guessing the mainboard will be the large board at back and not the one where the power goes to?

                              Comment

                              • Yoda79
                                Senior Member
                                • Dec 2021
                                • 56
                                • United Kingdom

                                #16
                                Re: samsung ue55nu7021k backlights working but blank screen

                                Originally posted by lotas
                                EMMc flash has been used in new models for a long time.
                                This model also has SPI Flash and EEPROM, but the software is in EMMc.
                                Sorry I got lost there but assume opening up the back and exposing the motherboard will provide clarity on whats faulty and needs to be replaced?

                                Comment

                                • Yoda79
                                  Senior Member
                                  • Dec 2021
                                  • 56
                                  • United Kingdom

                                  #17
                                  Re: samsung ue55nu7021k backlights working but blank screen

                                  So I've just tried another software update which is what I assume is a firmware update. I choose as per the photo and then it does something but returns to the main "No Signal" screen again. Checking the software version it's still what it was before.

                                  Also, some options don't seem to be available. Picture attached of some itmes greyed out!
                                  Attached Files

                                  Comment

                                  • vinceroger69
                                    Badcaps Legend
                                    • Mar 2012
                                    • 6714
                                    • uk

                                    #18
                                    Re: samsung ue55nu7021k backlights working but blank screen

                                    Originally posted by Yoda79
                                    So I've just tried another software update which is what I assume is a firmware update. I choose as per the photo and then it does something but returns to the main "No Signal" screen again. Checking the software version it's still what it was before.

                                    Also, some options don't seem to be available. Picture attached of some itmes greyed out!
                                    what is in the general menu?

                                    Comment

                                    • lotas
                                      Badcaps Legend
                                      • Jan 2016
                                      • 4578
                                      • Russia

                                      #19
                                      Re: samsung ue55nu7021k backlights working but blank screen

                                      If you reset via the "factory reset" service menu, you will get the TV as if it were from a store.
                                      https://www.wikihow.com/Reset-a-Samsung-TV

                                      Method 5

                                      Comment

                                      • Yoda79
                                        Senior Member
                                        • Dec 2021
                                        • 56
                                        • United Kingdom

                                        #20
                                        Re: samsung ue55nu7021k backlights working but blank screen

                                        Originally posted by vinceroger69
                                        what is in the general menu?
                                        Hi, so just started the tv again and the no signal page is not showing properly. Photo of this attached as well as a photo from before when this page was showing properly. I've also attached a photo of the main settings menu which too isn't showing properly. I'll later to see if it displays correctly.

                                        I'm guessing this doesn't help much?
                                        Attached Files

                                        Comment

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