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SONY KDL-55HX850 : No backlight, no error code, rest OK

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    #21
    Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

    Originally posted by Jojo337 View Post
    Hi !


    F2001 : Continuity OK (beeping), 0.001v, 0 ohm



    1) LED_ON is ~-0v in standby and 3.28v TV on

    2) VLED_VCC are 0v in standby, go up to 0.140v EACH 4 VLED_VCC for 2 secs and go down to 0V 3 sec later progessively.

    Thanks again !
    LED back light in this Sony are parts of VLED_VCC circuits, if there OPEN LED Ziner Diode all Circuits turned off and the set remain ON with no error. time to repair LED BL. as i wrote before search for other hands to help you with this risky job.

    Comment


      #22
      Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

      Originally posted by Jojo337 View Post
      Hi !


      F2001 : Continuity OK (beeping), 0.001v, 0 ohm



      1) LED_ON is ~-0v in standby and 3.28v TV on

      2) VLED_VCC are 0v in standby, go up to 0.140v EACH 4 VLED_VCC for 2 secs and go down to 0V 3 sec later progessively.

      Thanks again !
      Now remove the connector from CN6601 and repeat the same test on VLED_VCC pin again.
      BTW, you did already test D6602, 03, 12, 13?
      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


        #23
        Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

        No power to the TV:
        Check the resistance of R6707.
        Turn on the TV and check the DC V between the two legs of C6530, be real careful since you are working on the Hot deadly side of the circuit., then check the DC V between the negative leg of C6530 against each leg of R6707.
        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


          #24
          Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

          I was hopping that the leds be all good but my hope is going down

          Anyway here are the results, if my tests are correct :

          Diodes (multimeter to diode mode) D6602, 03, 12, 13:
          1.140v 0.425
          1.140v 0.425
          1.140v 0.425
          1.145v 0.423

          If I disconnect CN6601 everything is at 0v except 0.7V pin 11 LD_ERR
          (startup or not) The TV works fine behind except of course BL

          R6707 2.2ohm

          Stby C6530 395v, 13.88v with postive on R6707 (the two legs)
          TVON same but 14v on the two legs.

          Thanks

          Comment


            #25
            Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

            Originally posted by Jojo337 View Post
            I was hopping that the leds be all good but my hope is going down

            Anyway here are the results, if my tests are correct :

            Diodes (multimeter to diode mode) D6602, 03, 12, 13:
            1.140v 0.425
            1.140v 0.425
            1.140v 0.425
            1.145v 0.423

            If I disconnect CN6601 everything is at 0v except 0.7V pin 11 LD_ERR
            (startup or not) The TV works fine behind except of course BL

            R6707 2.2ohm

            Stby C6530 395v, 13.88v with postive on R6707 (the two legs)
            TVON same but 14v on the two legs.

            Thanks
            So there is no action even when the output of the power supply is not connected to the LED driver board, the power supply should put out around 50V, then if there is error the power supply will be shutdown due to error, right now the SMPS IC for the LED power supply is getting the VCC (13V) to run, but no action.
            There are many LED strings in this panel and they are driven by many LED drivers, so the one with good LED should at least flash on for seconds before the protection kicks in.
            BTW, you did leave the meter in place to monitor VLED pin of CN6601 when TV is turned on to catch the Voltage when TV is first turned on, correct?
            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


              #26
              Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

              I retested CN6601 not plugged, meter in place, first turn on, in fact all pins of CN6601 except NC and LD_ERR are -0.01v in stby and goes "down" to -0.02v when turning on.

              No flash at all from leds even a micro flash (verified in dark room).
              Last edited by Jojo337; 10-31-2020, 02:34 PM.

              Comment


                #27
                Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                Opening up the LCD panel is the last thing I would do since if you have never done one you can easily damage the screen, damage the tab bonding.
                I will look at the spec of the SMPS IC to do more verification.
                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


                  #28
                  Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                  I already do it for a samsung 40d5003 (in fact I'm waiting the new leds to come...) but here it's a 55, glass panel in front (strange design even if "beautiful").

                  SMPS IC : IC6701 ?

                  Comment


                    #29
                    Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                    Originally posted by Jojo337 View Post
                    I already do it for a samsung 40d5003 (in fact I'm waiting the new leds to come...) but here it's a 55, glass panel in front (strange design even if "beautiful").

                    SMPS IC : IC6701 ?
                    Yes, that is the IC, need to look for spec sheet and see if there is error detection pin that will put it into shutdown mode.
                    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


                      #30
                      Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                      Impossible to find the sheet, maybe this is the same ?
                      https://www.datasheetq.com/CXD9969P-doc-Sony (lack the A)

                      Comment


                        #31
                        Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                        I found the schematic of how the CXD9969 is used.
                        Please check the Voltage on pin 1, and pin 8 of the IC against the negative leg of C6530.
                        Attached Files
                        Last edited by budm; 10-31-2020, 06:40 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


                          #32
                          Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                          Hi,

                          CXD9969AP IC6701
                          STBY : Pin 1 0.1v - Pin 8 13.8v
                          ON : Pin 1 0.1v - Pin 8 14v

                          Comment


                            #33
                            Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                            So I got some time today to dissasembly it...
                            It was a nightmare, but I got the 4 led strips. One led was down.
                            But during disassembly of each, the first led self destruct itself (sticked to one of the reflector layer). When testing the first led never light up (I suppose broken during disassembly) but every other do... except one lost in one strip, it sure be defective befor I didn't touched it.

                            I'm ordering all 4, I hope I didn't destroyed any other thing (I reassembled it without screws and it seemed ok, even the picture seems ok but not sure if there is any lines... I will see.)

                            Thanks.

                            Comment


                              #34
                              Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                              Ok, then it looks like it was a bad backlight/s, trying to figure out why it could not be determined by just seeing if there was expected voltage on powerboard at backlight connector with backlights unhooked??

                              Comment


                                #35
                                Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                Can we see the LED strips?
                                What did you use to power up the strips? So how many strips are bad? Two?
                                BTW, pin 1 Voltage which is the Boost Voltage sensing pin to make sure the PFC Boost Voltage is not too low, it should be > 2V on that pin 1, at 0.1V it thinks that the PFC Voltage is bad so it will stay in protection mode.
                                Last edited by budm; 11-01-2020, 05:11 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


                                  #36
                                  Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                  Here are the pictures of the led strips.
                                  All 4 are defective now (the first led was "sticked" to a plastic reflector, maybe by heat...

                                  I got a led tester. I put LED + to one of the + of the strips, and with the LED - I go to all - of the strips, each - illuminate 8 leds.

                                  Just one led was already defective it seems, looks cracked. By disassembly it I certainly broke the first leds of each 4 because they were sticked to the reflector, IDK why, there isn't tape.
                                  Attached Files

                                  Comment


                                    #37
                                    Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                    i don't think its your fault... because heat and the reflector very close to leds surface. just dont forget to clean the edge of the reflector to have clean display..before 3year or more i had got this edge 7030 led. i removed them all with heat gun and placed pasta then stick new ones after all are in place and straight i applied the heat from downside of the strips so all got in place with good middle ground contact.. on aliexpress i got them 100 pieces for about 5$

                                    Comment


                                      #38
                                      Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                      Hello all.

                                      The new LEDS are in place.
                                      Nothing seems to be "more broken" after I dissasemble it.

                                      However the backlight still doesn't works

                                      Any others ideas, maybe it's the PSU ? The driver LED seems cold when touching.
                                      With my phone flash I see that the BL is not at 0 in the settings

                                      Thanks and have a good day !

                                      Comment


                                        #39
                                        Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                        Ok so I replaced the PSU and the TV works, however there is two lines in the screen, so maybe I broke IT or it was already there, I don't know !

                                        Anyways the PSU was faulty !

                                        Comment


                                          #40
                                          Re: SONY KDL-55HX850 : No backlight, no error code, rest OK

                                          Originally posted by Jojo337 View Post
                                          Ok so I replaced the PSU and the TV works, however there is two lines in the screen, so maybe I broke IT or it was already there, I don't know !

                                          Anyways the PSU was faulty !
                                          So if you check the Voltage per my post #35, what do you get?
                                          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

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