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Sony KDL-46NX720 possible purchase

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    Sony KDL-46NX720 possible purchase

    I have the chance of buying this TV for $100.
    It was diagnosed by a tech, that it is a panel problem.
    It turns on for 6 seconds and then turns off.
    That is all I know for now.
    Would you get it?
    It looks like a nice 3D, smart LED TV. It's tempting, but I'm afraid also, because I know that here we haven't repaired many of these yet.
    It doesn't come with a stand either.
    I have asked if it shows some error code. I'm waiting for an answer.
    I'm not really confident in these tech diagnosis. They may be over the phone, or sometimes they give the wrong answer. It happened in the past that I have picked up a TV with tech diagnosed problem and it turned out that it was something completely different problem.

    Edit: just found out that it blinks 4 times.
    Last edited by tibimakai; 08-08-2013, 09:22 AM.

    #2
    Re: Sony KDL-46NX720 possible purchase

    This is in the service manual:
    4X Blink – Balancer Error
    The 4X error code is only used on models incorporating local
    dimming LED backlighting. If a failure occurs on the LD board or one
    of the LED's fails in the panel the TV will shut down and display this
    diagnostic code. Models using conventional non-local dimming LED
    backlighting do not utilize this error code.
    I guess it could be one of the LEDs that went bad?

    Comment


      #3
      Re: Sony KDL-46NX720 possible purchase

      I would take a chance on it, and if it did turn on to be a panel problem you could probably make some profit from the parts itself. The psu and main board itself are probably worth $100+ itself since its the newer led and a sony. From my experience every tv I bought that had a "tech diagnosed" was so far off...

      Comment


        #4
        Re: Sony KDL-46NX720 possible purchase

        I wouldn't count on what the parts are "probably" worth. I'd be buying this TV with the assumption that it has a bad panel, unless you can prove otherwise, and I'd check the value of the parts. If there is an over abundance of parts for sale for this model, you may not get much for them. Also, if there isn't much of a history of internal failure with this model, you may not be able to sell them quickly. The bottom line is that there are WAY too many non-working TVs out there to gamble with your hard-earned money.

        Edit: It wouldn't be the first time a tech's diagnosis is way wrong, though.
        Last edited by capkid; 08-08-2013, 07:11 PM.
        LG Plasma Mal-Discharge Correction Service

        Comment


          #5
          Re: Sony KDL-46NX720 possible purchase

          I have picked it up. Got the brand new stand with it also.
          It turns on, it shows picture and then turns off and blinks 4x error code.
          This seems like a backlight problem.

          Comment


            #6
            Re: Sony KDL-46NX720 possible purchase

            Hopefully, the diagnosis is incorrect or it's fixable, but I keep seeing "4 blinks" and "bad panel" references everywhere.
            Last edited by capkid; 08-08-2013, 07:39 PM.
            LG Plasma Mal-Discharge Correction Service

            Comment


              #7
              Re: Sony KDL-46NX720 possible purchase

              I noticed the wording with sonys and "bad panel" I had one sony lcd that some tech said that the panel had to be replaced... He just didn't say why. So I decided to open up the tv and found several bad CCFLs... Replaced them and it came back to life!

              So what he really meant was that the whole panel was "bad" and had to be replaced (since the ccfls in the panel were bad) I don't see much tech's ever touching or even attempting to replace the lamps.

              Comment


                #8
                Re: Sony KDL-46NX720 possible purchase

                They probably go by the service manual. If the manual mentions bad LCD panel, they don't even bother repairing it.

                Comment


                  #9
                  Re: Sony KDL-46NX720 possible purchase

                  Originally posted by Glitcher View Post
                  I noticed the wording with sonys and "bad panel" I had one sony lcd that some tech said that the panel had to be replaced... He just didn't say why. So I decided to open up the tv and found several bad CCFLs... Replaced them and it came back to life!

                  So what he really meant was that the whole panel was "bad" and had to be replaced (since the ccfls in the panel were bad) I don't see much tech's ever touching or even attempting to replace the lamps.
                  Yeah, I could see a tech saying, "I'm not going to waste my time. I've got better things to do". The Sanyo LCDs are like that - lots of bad CCFLs that can be replaced with time and patience.
                  Last edited by capkid; 08-08-2013, 08:40 PM.
                  LG Plasma Mal-Discharge Correction Service

                  Comment


                    #10
                    Re: Sony KDL-46NX720 possible purchase

                    I had a little time and took some pictures.
                    Not sure where to start.
                    BL_ERR is 1.68V in standby, when I turn it on, it drops to 0.235V(don't remember the right number right now, I don't have my notes with me) and when the error kicks in, then goes back to 1.68V.
                    There are to many xxxx_On inputs and I don't know how to hard start the power supply.
                    It even had PFC_On.
                    Any input would be appreciated.
                    Attached Files

                    Comment


                      #11
                      Re: Sony KDL-46NX720 possible purchase

                      Any ideas where should I start?
                      This is a 3D TV.
                      Attached Files

                      Comment


                        #12
                        Re: Sony KDL-46NX720 possible purchase

                        What do you get at LD ERROR?
                        Follow-up: After looking at the bottom side of the board, all the LED_vcc are tied together, same for the LED_Ground, so the Vcc_LED voltage from this board must be fed to the other LED driver board some where, the board in the middle?. The output voltage is not very high either since those 4 filter caps are rated only at 50VDC.
                        Last edited by budm; 09-30-2013, 10:57 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: Sony KDL-46NX720 possible purchase

                          I will do those measurements soon, but the LED driver board is the one in the middle. There are four ribbon cables coming out at the top of the board and they are going through some cut outs in the metal cover to the LEDs.

                          Comment


                            #14
                            Re: Sony KDL-46NX720 possible purchase

                            Can we see the closed up pictures of that board?
                            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: Sony KDL-46NX720 possible purchase

                              I will take a picture tomorrow.
                              I have measured the LD_Error, it's 0.66V before start up. When starts up, it drops to 0.04V and when the LEDs turn on, it goes back to 0.66V and when it shots down, it goes toward 0V.
                              The VLED_Vcc is 27V, when LEDs turn on.

                              Comment


                                #16
                                Re: Sony KDL-46NX720 possible purchase

                                I have took some pictures with the LED driver board and there are some test points on this board.
                                Before the output connectors there are a bunch of test points and they are all 4.69V when the LEDs are on.
                                Next to each output connector there is a single test point, which I guess is the LEDs supply voltage. They are all 27.05V.
                                There are 6 test points above the 6 ICs, called FAIL 1-6.
                                FAIL 1,2,3,4 and 6 show 2.825V before the LEDs turn on and after they turn on it drops to .589V.
                                There is a difference at FAIL 5, where the 2.825V is the same, but after that it dropes to .395V only. I guess, this should indicate something is bad, no?
                                Attached Files

                                Comment


                                  #17
                                  Re: Sony KDL-46NX720 possible purchase

                                  Nobody has any ideas?

                                  Comment


                                    #18
                                    Re: Sony KDL-46NX720 possible purchase

                                    Did you download the service manual, I will have to download it also and look at it also.
                                    http://elektrotanya.com/?q=showresul...oria=&kat2=all
                                    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


                                      #19
                                      Re: Sony KDL-46NX720 possible purchase

                                      I have it. It shows LCD panel or LD board(LED Driver). LD board schematic is not included for this model, only the 40" one is included, which it looks different.
                                      Both documents are over 17 MB, so I can't upload them here.

                                      Comment


                                        #20
                                        Re: Sony KDL-46NX720 possible purchase

                                        I guess I will have to get the part number from those six ICs from the LD board.
                                        They are not given in the SM.

                                        Comment

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