Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

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  • Grannyrogers
    Member
    • Mar 2014
    • 14
    • United states

    #1

    Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

    No sound, No backlight, No standby light..

    When the power button is pressed, nothing happens.

    Tests that I have done:

    Power Supply:

    Legs of large capacitor registers 402v consistently

    With logic and inverter board unplugged, I registered 5v only on connector pins labeled "5v"

    With logic and Inverter plugged in, I registered 24.5v to the inverter and 14.45v and 5v to the logic board.

    Logic Board

    regulators:

    u3
    AC 7A1L
    17-33L
    PIN1=0
    PIN2=.78
    PIN3=1.68

    U5
    AC 7A1L
    17-33L
    PIN1=0
    PIN2=.82
    PIN3=1.69

    U6
    AZ1084S
    -ADJE1
    713J71
    PIN1=.50
    PIN2=.81
    PIN3=1.69

    U8
    A1084S
    -ADJE1
    713J71
    PIN1=.42
    PIN2=.80
    PIN3=1.69

    U9
    AC 713L
    1117L
    PIN1=0
    PIN2=.09
    PIN3=.81

    U10
    AC 7A1L
    17-33L
    PIN1=0
    PIN2=3.30
    PIN3=5.03

    U11
    AC713L
    1117L
    PIN1=.01
    PIN2=.04
    PIN3=.81

    U28
    J201
    78M12
    PIN1=14.45
    PIN2=.01
    PIN3=11.93

    U31
    UTC
    78D05AL
    05UKCG
    PIN1=11.93
    PIN2=.01
    PIN3=4.99

    U33
    AC 7A1L
    17-33L
    PIN1=0
    PIN2=.72
    PIN3=1.69

    Any Help is appreciated. Thanks
    Last edited by Grannyrogers; 03-27-2014, 04:42 PM.
  • Grannyrogers
    Member
    • Mar 2014
    • 14
    • United states

    #2
    Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

    Here are some Pictures:
    Attached Files

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

      You need to retest the input voltage to pin 3 of U3, U5, U6, U8, U9, U11, U33: they are way too low.
      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

      • Grannyrogers
        Member
        • Mar 2014
        • 14
        • United states

        #4
        Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

        Thanks for replying so quick Budm.

        I rechecked all of them with the MM black wire to chassis, and I am still getting the same values.

        I forgot to mention that I replaced two bulging capacitors on the powersupply. they were 2200 uf 10v each.

        Do you think the main board is no good?

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

          The problem is on the main board right now due to very low DC input voltages feeding those regulators, need to find out why you are getting only 1.69V,and 0.81V to those input pins.
          One things that does not make sense is that you are able to get the 24V isnce with that low voltages on the main board, it will not function to send out the PS_ON signal to turn on the 24V power supply.
          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

          • Grannyrogers
            Member
            • Mar 2014
            • 14
            • United states

            #6
            Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

            Is there anything else I can test?

            Comment

            • Grannyrogers
              Member
              • Mar 2014
              • 14
              • United states

              #7
              Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

              Originally posted by budm
              The problem is on the main board right now due to very low DC input voltages feeding those regulators, need to find out why you are getting only 1.69V,and 0.81V to those input pins.
              One things that does not make sense is that you are able to get the 24V isnce with that low voltages on the main board, it will not function to send out the PS_ON signal to turn on the 24V power supply.
              I did some reading, and it seems the 24v is active because the PS-ON signal coming from the mainboard is low. Normally, when the TV on/off swtch is pressed, the voltage to the PS_ON drops which tells the power supplies to initiate the 24v

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                Hmm, most Vizio uses active high, but may be this one is active low. What is voltage at PS_ON when TV is in standby mode? The main key right now is to find out why we are having really low voltage feeding the regulator ICs. You may have trace out to see if all those input pins are tied together on the one with 1.69VDC reading, then trace out where it goes after that.
                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

                • Grannyrogers
                  Member
                  • Mar 2014
                  • 14
                  • United states

                  #9
                  Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                  I cant tell if TV is in standby mode or not because the standby light is off. However, the voltage at PS_ON is 1.205v.

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                    It should toggle when the power switch is turned on and off, if it does not change state, then that control line is also not working.
                    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

                    • Grannyrogers
                      Member
                      • Mar 2014
                      • 14
                      • United states

                      #11
                      Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                      Nothing happens when I toggle the on and off switch. The voltage does not fluctuate, so that control line appears to be dead as you stated. Mystery deepens.

                      I get .02v at on/off and .80 at IVT_DIM

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                        Nothing is going to work right until we get the correct voltages from those regulators.
                        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

                        • Grannyrogers
                          Member
                          • Mar 2014
                          • 14
                          • United states

                          #13
                          Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                          I tested this 8 legged thing and it has the correct 5 volts on one side and the 1.69v that we see going to the regulators on the other side. Oh and that 1.69v is now 1.65v. It is decreasing. I am going to upload a pic of it. I think it is called variable capitance diode.

                          Could this be problem?
                          Last edited by Grannyrogers; 03-29-2014, 04:50 PM.

                          Comment

                          • Grannyrogers
                            Member
                            • Mar 2014
                            • 14
                            • United states

                            #14
                            Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                            Hey budm,

                            So I ordered a mainboard off ebay for $38 and I just installed it; however, when I press the power button all I got was the standby light and backlight. I tested the voltages and I got normal voltages. 5.03v, 15.06v and 24v. However, shortly after, I smelt something burning and when I tried turning tv off, nothing would happen. I unpplugged the tv then replugged it back into the outlet and now it is as before, just a black screen with no standby light. I retested the voltages and they are, once again, just as on the old board. All low voltages going to several regulators except one. Do you think a bad Tcon board could cause this or is it a bad power supply?
                            Last edited by Grannyrogers; 03-31-2014, 05:17 PM.

                            Comment

                            • Grannyrogers
                              Member
                              • Mar 2014
                              • 14
                              • United states

                              #15
                              Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                              Oh. On the new board, an 8 prong mosfet is burnt. It is located beside the connector from the PS. The volts coming from it matches the volts going to the regulators.
                              Last edited by Grannyrogers; 03-31-2014, 07:02 PM.

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #16
                                Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                                Can we see a picture of this burnt MOSFET? The seller probably didn't test the board, they rarely do.
                                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                Comment

                                • Grannyrogers
                                  Member
                                  • Mar 2014
                                  • 14
                                  • United states

                                  #17
                                  Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                                  Originally posted by tom66
                                  Can we see a picture of this burnt MOSFET? The seller probably didn't test the board, they rarely do.
                                  Hi tomm66, thanks for assisting.

                                  The board I bought was good when I got it. The original one had no standby light, no sound, no backlight, but when I installed the new one, I saw standby light and I got a white backlight then I smelt something burning.

                                  Upon closer inspection of the original board i notice that the same MOSFET was burnt as well. I have uploaded pictures of both.

                                  What do you think is causing the mosfet to burn up?
                                  Attached Files

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #18
                                    Re: Vizio VW26LHDTV10F, No Sound, Backlight and Standby Light

                                    It looks like it is being used as a switch.
                                    Last edited by budm; 03-31-2014, 09:50 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

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