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Vizio E65-E3 Dead after backlight replacement

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    #41
    Re: Vizio E65-E3 Dead after backlight replacement

    TV BL LEDs function with currents not Volts, so it must be each LED contained 1 ziner diode.

    Normal LED for lighting application include RGB one they dont need ziner as they calculated of LEDs amounts and volts.

    who are against this fact bring proof you have TV BL with out ziner.

    Comment


      #42
      Re: Vizio E65-E3 Dead after backlight replacement

      Originally posted by Diah View Post
      TV BL LEDs function with currents not Volts, so it must be each LED contained 1 ziner diode.

      Normal LED for lighting application include RGB one they dont need ziner as they calculated of LEDs amounts and volts.

      who are against this fact bring proof you have TV BL with out ziner.
      What zener has to do with current?
      The current is defined by low side mosfet together with sense resistor and controller IC, basically this is current source circuit. Voltage drop across LED depends on current going through it. See I-V curve in datasheet.

      Comment


        #43
        Re: Vizio E65-E3 Dead after backlight replacement

        Originally posted by alfatv View Post
        What zener has to do with current?
        The current is defined by low side mosfet together with sense resistor and controller IC, basically this is current source circuit. Voltage drop across LED depends on current going through it. See I-V curve in datasheet.
        we are talking on the LED units used for TV backlight... not the circuit of it. again TV LED UNIT backlight must contained fc zener diode. with out it (if you use pure LED units the circuit will be OPEN ) no flashing or turn on at all.

        Comment


          #44
          Re: Vizio E65-E3 Dead after backlight replacement

          let me just say thank you guys for helping me figure this thing out. I just got into this kinda stuff a few months ago and have learned alot.

          So...it turns out..there are diodes on green side of the board as well!!
          HaHa! I found 6 that are not reading correctly. do i need to pull them out of circuit to get an accurate test?

          Comment


            #45
            Re: Vizio E65-E3 Dead after backlight replacement

            Originally posted by a460guy View Post
            let me just say thank you guys for helping me figure this thing out. I just got into this kinda stuff a few months ago and have learned alot.

            So...it turns out..there are diodes on green side of the board as well!!
            HaHa! I found 6 that are not reading correctly. do i need to pull them out of circuit to get an accurate test?
            it seem you believe only on ebay and yours replacements strips. last word from my side yours strips are wrong 10000% and if i were wrong i will never inter this forum again. its disgusted when i read wrong comments.

            Comment


              #46
              Re: Vizio E65-E3 Dead after backlight replacement

              Originally posted by Diah View Post
              we are talking on the LED units used for TV backlight... not the circuit of it. again TV LED UNIT backlight must contained fc zener diode. with out it (if you use pure LED units the circuit will be OPEN ) no flashing or turn on at all.
              Yes, I am talking about the same thing and these LEDs need circuit to operate.
              Please draw a circuit, show voltages and currents, then explain what is the purpose of zener diode.
              If you want to talk about specific part number, please share datasheet.

              Comment


                #47
                Re: Vizio E65-E3 Dead after backlight replacement

                ssoo....about these diodes? lol

                Comment


                  #48
                  Re: Vizio E65-E3 Dead after backlight replacement

                  Maybe lift just one out of circuit and retest it, see what you get.

                  Comment


                    #49
                    Re: Vizio E65-E3 Dead after backlight replacement

                    Originally posted by dick_barton View Post
                    Post #3 you say
                    Pin 1 Stby = 0V, Out of standby = 0.001V
                    which is odd since normally the standby voltage goes from 0V to 3V or 3V to 0V

                    Post #11
                    Shows no voltages on the led connector pins.

                    Post #17
                    C2 voltage at standby = 170V and out of standby 164V
                    The voltage should increase I believe to around 380V and not drop

                    I think you are missing the led driver supply and may well be linked to the C2 low voltage.

                    What is the led driver IC part number. A photo of the underside of your power supply could prove usefull.

                    Is this the led driver ic? If so it is FAN7930BG..
                    Attached Files

                    Comment


                      #50
                      Re: Vizio E65-E3 Dead after backlight replacement

                      Also pulled those diodes and they checked out ok......

                      Comment


                        #51
                        Re: Vizio E65-E3 Dead after backlight replacement

                        "Is this the led driver ic? If so it is FAN7930BG.."

                        That's on the hot side of the power supply and it is the PFC controller

                        Comment


                          #52
                          Re: Vizio E65-E3 Dead after backlight replacement

                          So some added info that may be pertinent. I just picked up an E60-E3 yesterday that needs LED's for being dim / blue in color. The way this set is configured is there are two LED connectors on the back chassis, and the one on the Main board. It looks like they split for 5 on top and 5 on bottom. The LED switched voltage is 16.8 volts originating in the Power Supply and routed to the Main. The Main has all the LED control circuitry. I am not sure if the LED switched is controlled by PSON or VSNS, but since you have the correct voltage for PSON then I might suspect VSNS is the issue. VSNS goes to 2.3 volts in operate on this set.

                          PFC voltage was 165 in standby and 364 volts in operate with everything connected.

                          I disconnected the bottom LED connector, which would effectively open 5 strips. When commanded on the LED's illuminated and on the top half and the PFC voltage came up to 364 volts as before.
                          Last edited by RDC55; 04-17-2021, 09:55 AM.

                          Comment


                            #53
                            Re: Vizio E65-E3 Dead after backlight replacement

                            Originally posted by RDC55 View Post
                            So some added info that may be pertinent. I just picked up an E60-E3 yesterday that needs LED's for being dim / blue in color. The way this set is configured is there are two LED connectors on the back chassis, and the one on the Main board. It looks like they split for 5 on top and 5 on bottom. The LED switched voltage is 16.8 volts originating in the Power Supply and routed to the Main. The Main has all the LED control circuitry. I am not sure if the LED switched is controlled by PSON or VSNS, but since you have the correct voltage for PSON then I might suspect VSNS is the issue. VSNS goes to 2.3 volts in operate on this set.

                            PFC voltage was 165 in standby and 364 volts in operate with everything connected.

                            I disconnected the bottom LED connector, which would effectively open 5 strips. When commanded on the LED's illuminated and on the top half and the PFC voltage came up to 364 volts as before.
                            Finally something meaningful.
                            How many LEDs per string?
                            Can you take pictures of measurement points? Also indicate how power is routed through LEDs.
                            Last edited by alfatv; 04-17-2021, 11:41 AM.

                            Comment


                              #54
                              Re: Vizio E65-E3 Dead after backlight replacement

                              Well this 60 inch set is different but close. There are 5 LED's (X2 per row) per string with a total of 10 strings with 5 rows - at 3 volts per LED that makes LED + approximately 16 volts per string - a bit high but the low side (10 Mosfets) will control current for each string and consequently voltage drop.

                              I am thinking / guessing your set has 6 LED's (x2 per row) per string with a total of 12 strings with 6 rows. That means your LED voltage will be closer to 22 volts, and that you have 12 Mosfets to control the drive.

                              I attached a picture of the E60-E3 back for reference. I have not pulled the panel yet and will not do so for another week awaiting LED's to arrive. You can see the LED connectors above and below the Power Supply with each having 5 black wires which should be the low side control lines.

                              So, with all that said, you probably should be focused on why you don't have PFC boost voltage. A lot of this is new to me and schematics are rare, but most likely you will never make LED voltage unless PFC boost is working. I got some nice help from dick_barton and R_J on a different set but it also used the FAN7930 PFC controller. My issue turned out to be a bad capacitor, but your board is newer and I can only speculate it is an issue with control - as in VCC for the FAN7930C not only has to be made, but it needs to be switched to activate the PFC boost controller.

                              This is the thread where I got the help:

                              https://www.badcaps.net/forum/showthread.php?t=94738

                              I will try to check a bit closer to see just what can be measured and what is the control logic for enabling PFC, or maybe one of the experts will chime in.
                              Attached Files
                              Last edited by RDC55; 04-17-2021, 01:39 PM.

                              Comment


                                #55
                                Re: Vizio E65-E3 Dead after backlight replacement

                                Originally posted by RDC55 View Post
                                .
                                the problem in this threat, OP replaced all strings, and when i asked him to test each LED unit, he found the LED with out any zener in reverse way built in led units..

                                TV LED should have build in zener diode in reverse way.. if you have any LED backlight of TV test them with diode mode to see how the zener build in,,

                                normal lighting LED dont need this zener. so this is the problem in this threat. as OP test there are bo any zener reading over all LEDs

                                Comment


                                  #56
                                  Re: Vizio E65-E3 Dead after backlight replacement

                                  Do you think there is a workaround soultion? adding diodes in line maybe? If i tell the seller they work when i test them but when they are installed they do not.......they are going to tell me to kick rocks. Wish i still had the old ones.....to be 100% sure.. i also tested a samsung and a lg led strip i had laying around and they both tested with a zener.

                                  Comment


                                    #57
                                    Re: Vizio E65-E3 Dead after backlight replacement

                                    Originally posted by Diah View Post
                                    the problem in this threat, OP replaced all strings, and when i asked him to test each LED unit, he found the LED with out any zener in reverse way built in led units..

                                    TV LED should have build in zener diode in reverse way.. if you have any LED backlight of TV test them with diode mode to see how the zener build in,,

                                    normal lighting LED dont need this zener. so this is the problem in this threat. as OP test there are bo any zener reading over all LEDs
                                    I guess I don't quite get the purpose of the zener. I agree, most all TV LED's will have a zener, but it is never conducting unless the LED fails open. Therefore, its purpose is to keep the string active in the event that an LED does fail open, or prevent an overvoltage condition if somehow the string is connected with the wrong polarity - which might be destructive without resistive current limiting.

                                    @budm is quite the reliable source of information on this site, and in this thread he comments that not all LED's have the zener.

                                    https://www.badcaps.net/forum/showthread.php?p=806674

                                    The other issue is what is causing no boost voltage. Yes, perhaps LED issues could cause a shutdown (and good troubleshooting always asks what was the last thing I did), but when I disconnected 5 rows the circuit did not function that way, and boost voltage was normal.

                                    And, just in case anyone is interested the numbers on the Power Supply IC's on the bottom:

                                    U101 PFC Controller - FAN7930BG
                                    U1 guessing standby SMPS Controller - EA18363 - KZ60921 - TXD6241
                                    U301 guessing LLC controller for LED voltage - MSP1626 - HR1001 - G483801.8

                                    LED Controller on the Main

                                    U400 - AS3820E - 1618XAC
                                    Mosfet Driver - 09N10 - 6HGE
                                    Last edited by RDC55; 04-17-2021, 07:11 PM.

                                    Comment


                                      #58
                                      Re: Vizio E65-E3 Dead after backlight replacement

                                      Originally posted by RDC55 View Post
                                      I guess I don't quite get the purpose of the zener. I agree, most all TV LED's will have a zener, but it is never conducting unless the LED fails open. Therefore, its purpose is to keep the string active in the event that an LED does fail open, or prevent an overvoltage condition if somehow the string is connected with the wrong polarity - which might be destructive without resistive current limiting.
                                      That's right, they are used for protection and they do nothing during operation.
                                      Also, I believe they are causing short circuits in some older Samsung TVs either themselves of after LED burns out and opens, that way the rest of LEDs are still operational and user is not so mad.

                                      Comment


                                        #59
                                        Re: Vizio E65-E3 Dead after backlight replacement

                                        Originally posted by RDC55 View Post
                                        .
                                        this is wrong references you linked.. you should read the threat to the end, where the OP put in led with zener then it work. i dont need to argue any more about this all up to yours mind. Last words...

                                        ALL TV brands Type LED BACKLIGHT should had zener.

                                        the zener not only for protection. its much important as you think.

                                        Comment


                                          #60
                                          Re: Vizio E65-E3 Dead after backlight replacement

                                          Originally posted by a460guy View Post
                                          Do you think there is a workaround soultion? adding diodes in line maybe? If i tell the seller they work when i test them but when they are installed they do not.......they are going to tell me to kick rocks. Wish i still had the old ones.....to be 100% sure.. i also tested a samsung and a lg led strip i had laying around and they both tested with a zener.
                                          No way at all,,,,, i am sure 1000000% the strips you have in hand mounted with wrong LED units( normal LED ) not designed for TV LED backlight ( LEDs with zener in reverse )

                                          Comment

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