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Vizio 40” V405-H19 has backlight, no display

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    #21
    Re: Vizio 40” V405-H19 has backlight, no display

    might have gotten a bad mainboard from sj, maybe send it back and have them send you another.

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      #22
      Re: Vizio 40” V405-H19 has backlight, no display

      Good lord. Here I was complaining about tcons being built into main boards but this guy's got a tcon built into the panel board! Vizio is one step ahead in the cost cutting / making it hard to fix game
      Don't fear the repair...

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        #23
        Re: Vizio 40” V405-H19 has backlight, no display

        Originally posted by nomoresonys View Post
        might have gotten a bad mainboard from sj, maybe send it back and have them send you another.
        But if the vgh and vhl are wrong, isn't that something only related to the tcon? Genuinely asking cause I don't know where those voltages are generated.
        Don't fear the repair...

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          #24
          Re: Vizio 40” V405-H19 has backlight, no display

          VGH and VGL are generated on t-con.
          I assume no responsibility for any stupid suggestions I might post.

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            #25
            Re: Vizio 40” V405-H19 has backlight, no display

            Originally posted by dskall View Post
            VGH and VGL are generated on t-con.
            Thanks. Thats what I suspected. So in this case it couldn't be a main board problem making those vgh and vgl wrong?
            Don't fear the repair...

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              #26
              Re: Vizio 40” V405-H19 has backlight, no display

              As far as voltages the main only supplies 12v. Required panel voltages are generated by t-con
              I assume no responsibility for any stupid suggestions I might post.

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                #27
                Re: Vizio 40” V405-H19 has backlight, no display

                Originally posted by dskall View Post
                As far as voltages the main only supplies 12v. Required panel voltages are generated by t-con
                The main board has to give the tcon some other small voltage signals for the picture data...most of the pins on the connector going to the tcon are those, right? And a few are for the 12v. I guess I should try lookup a pinout to see for sure what the mb sends.

                Also while they're busy integrating boards that they shouldnt be, who's to say they haven't put half of the "tcon" on the mainboard and the other half on the panel boards??
                Last edited by triplefour; 07-28-2022, 09:41 PM.
                Don't fear the repair...

                Comment


                  #28
                  Re: Vizio 40” V405-H19 has backlight, no display

                  The main supplies 12v, data signals and some other information. The t-con generates the required panel voltages and timing signals to run the panel. The chip around your vgh and vgl test point is probably the one generating those voltages. So you either have a short or bad ic.
                  I assume no responsibility for any stupid suggestions I might post.

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                    #29
                    Re: Vizio 40” V405-H19 has backlight, no display

                    ok, if tcon is on the panel not mainboard, might be the dc to dc converter ic.

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                      #30
                      Re: Vizio 40” V405-H19 has backlight, no display

                      Wow, that was a lot of information and good Q/A. Is there a way to test the IC? I suppose I would need a pin out diagram and what the voltages should be.

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                        #31
                        Re: Vizio 40” V405-H19 has backlight, no display

                        You could check those test points for shorts. You could cut the traces and check the voltage. Check the caps around the ic. Check for 12v to the ic.
                        I assume no responsibility for any stupid suggestions I might post.

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                          #32
                          Re: Vizio 40” V405-H19 has backlight, no display

                          I don't know exactly how they work either but I think you want to look for 12v going in and 3.3v coming out on one of the pins.

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                            #33
                            Re: Vizio 40” V405-H19 has backlight, no display

                            Which of the 3 ICs do I check?


                            Attached Files

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                              #34
                              Re: Vizio 40” V405-H19 has backlight, no display

                              Looks like right one.
                              I assume no responsibility for any stupid suggestions I might post.

                              Comment


                                #35
                                Re: Vizio 40” V405-H19 has backlight, no display

                                There will be different voltages on each on the coils, so it's the middle and right but identify the markings to be sure.

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                                  #36
                                  Re: Vizio 40” V405-H19 has backlight, no display



                                  The only two voltages I found close to what you were asking was pin 1 starting from the top left above the “I” in “INX” which measured at 4.970V and pin 3 above the “N” at 12.63V. I tried looking up the chip but couldn't find anything specific.
                                  Attached Files

                                  Comment


                                    #37
                                    Re: Vizio 40” V405-H19 has backlight, no display



                                    I included the above drawing. Hopefully you can make sense of my scribble.

                                    I still need to draw a diagram of the other chip but I measured 12.63 volts as well as 5v. There were other voltages that measured between .600 and 1.5 volts.
                                    Attached Files

                                    Comment


                                      #38
                                      Re: Vizio 40” V405-H19 has backlight, no display

                                      I can't seem to find a datasheet on it either.

                                      Comment


                                        #39
                                        Re: Vizio 40” V405-H19 has backlight, no display

                                        Nice...tcon integrated into panel boards and secret ICs... they really don't want you to fix these

                                        If that ic is bad and there's no way to buy a new one then your only chance would be to take it from another TV but most ebay sellers don't tear off and sell the panel boards. Now that the tcon chips are there, maybe they should. I've been saving all my panel boards even tho they don't have tcon on them.
                                        Last edited by triplefour; 08-02-2022, 09:44 PM.
                                        Don't fear the repair...

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