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VIZIO VX37L No picture or sound.

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    VIZIO VX37L No picture or sound.

    I have a Vizio VX37L that does not have a picture or sound. the Light in front will turn from orange to white when you push power but the tv does nothing. I will also not turn back off, you have to unplug it.
    All the voltages on the power supply seem correct so checked the regulators on the main board. they are as follows. Do they seem correct or do i need to change some out?

    AMC117
    f0722f

    U7 3.21
    1.11
    0.02

    U33 5.09
    3.22
    1.98

    U8 5.11
    3.25
    2.01

    U2 5.09
    3.26
    2.02

    U4 5.09
    3.28
    2.04

    K117515
    730

    U9 3.21
    1.49
    0.00

    #2
    Re: VIZIO VX37L No picture or sound.

    I did test the power supply and i have all the voltages except for A and B they read 0

    Comment


      #3
      Re: VIZIO VX37L No picture or sound.

      If you are reading 0V at A and B, A and B are the control signals generated by the main board to turn on the backlights and Dimming control. Are you getting PS_ON >3VDC?
      Can we see good clear pictures of the boards? Is this the same as your TV?
      http://s807.photobucket.com/albums/y...37L%20HDTV10A/
      You voltage reading of the regulators are a little confuse.
      If you look at the regulator 1117 series with the big tab up
      Fixed output regulator:
      Left pin (1) will be Ground
      Center pin or Tab (2) will be output pin
      Right pin (3) will be the input pin

      Adjustable output regulator (it will need two resistors, one is between Ground and Adj pin, another one is between Adj pin and Output pin):
      Left pin (1) will be the Adust pin.
      Center pin or Tab (2) will be output pin
      Right pin (3) will be the input pin

      This is the way to figure out if the adjustable regulator is good or not:
      Notes: we are looking at the regulator with the Big tab up (the big tab is tied internally to the center pin).
      Adjustable regulator will have two resistors attached to it, one resistor (Rfb) is between pin1 and pin2, another resistor (Rg) is between pin1 and ground. Pin3 is an input pin.
      The voltage between the Adjust pin (left pin) and the center pin (Pin2, output) will always be 1.25V +/- 2% (this is the precision voltage reference), if it is not, it is bad.
      To figure out what the output voltage should be: measure the voltage between pin 1 and ground and add 1.25V to that number, that is the output voltage on pin 2 but you have to make sure you do have 1.25 between pin 1 and 2 as noted above.
      So can you label the pins and the voltage you are reading on those regulators?
      AMC117
      f0722f

      U7 P/N?
      3.21
      1.11 This one does not look right
      0.02

      U33 P/N?
      5.09
      3.22 This one should be 3.3
      1.98

      U8 P/N
      5.11
      3.25 looks OK (1.25 +2.01 = 3.26)
      2.01

      U2 P/N?
      5.09
      3.26 looks OK (1.25 + 2.02 = 3.27)
      2.02

      U4 P/N?
      5.09
      3.28 looks OK (1.25 + 2.04 = 3.29)
      2.04

      K117515
      730

      U9
      3.21
      1.49 looks OK, it looks like 1.5V regulator.
      0.00
      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


        #4
        Re: VIZIO VX37L No picture or sound.

        The picture of the main board in your link is just like mine. same part number and all. I took the readings clockwise. so since the big tab is to the left i guess the way i listed them would be
        3
        2
        1
        I do have a PS_On reading of 3.07 which seems a tad low.
        The part numbers for the U regulators are all AMC117 f0722f except for U9. its a
        K117515 730

        Comment


          #5
          Re: VIZIO VX37L No picture or sound.

          how can i get the U33 up to 3.3 volts?

          Comment


            #6
            Re: VIZIO VX37L No picture or sound.

            You should re-test U33. If it still shows low 3.22V, it could be faulty and should be replaced. However, U7 looks worse, as budm pointed out.
            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


              #7
              Re: VIZIO VX37L No picture or sound.

              I retested it and its 3.22 still. I know theses are all adjustable regulators but i dont think i have any laying around. I do have a few A1-AS1117L but cant find a data sheet to see if they will work.

              Comment


                #8
                Re: VIZIO VX37L No picture or sound.

                If they do not have -33 after them or similar they may be adjustable but why take the risk? You could burn the main board due to over voltage. Digikey has voltage regulators for cheap:

                http://www.digikey.com/product-detai...4-1-ND/1217057
                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


                  #9
                  Re: VIZIO VX37L No picture or sound.

                  I replaced U7 and U33 both on a 42" Vizio, had low output voltage on U7 and U33 has a high failure rate.. both were same part#, I bought them from Digikey and even got extras since they were so cheap. After replacing them the TV now powers on and works fine.

                  Comment


                    #10
                    Re: VIZIO VX37L No picture or sound.

                    1117 series LDO from DIGIKEY:

                    SOT-223-3 style casing:

                    Adjustable:
                    http://www.digikey.com/product-detai...SCT-ND/1967218
                    http://www.digikey.com/product-detai...44-1-ND/586244

                    1.2V Fixed:
                    http://www.digikey.com/product-detai...40-1-ND/725525
                    http://www.digikey.com/product-detai...5-1-ND/1865519 1.2A

                    1.5V Fixed:
                    http://www.digikey.com/product-detai...SCT-ND/2121241 1A
                    http://www.digikey.com/product-detai...8-1-ND/1883983 950Ma
                    http://www.digikey.com/product-detai...26-1-ND/586226 1.2A

                    1.8V Fixed:
                    http://www.digikey.com/product-detai...SCT-ND/1967216

                    2.5V Fixed:
                    http://www.digikey.com/product-detai...SCT-ND/2121243 1A
                    http://www.digikey.com/product-detai...9-1-ND/1883984 950mA

                    3.3V Fixed:
                    http://www.digikey.com/product-detai...OSCT-ND/660708
                    http://www.digikey.com/product-detai...SCT-ND/3462387 1.1A

                    http://www.digikey.com/product-detai...28-1-ND/586228 1.2A

                    5V Fixed:
                    http://www.digikey.com/product-detai...SCT-ND/1967217
                    http://www.digikey.com/product-detai...7-1-ND/1865475
                    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


                      #11
                      Re: VIZIO VX37L No picture or sound.

                      And shipping is under $3 in continental US, I believe.
                      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


                        #12
                        Re: VIZIO VX37L No picture or sound.

                        Originally posted by MisterD View Post
                        I replaced U7 and U33 both on a 42" Vizio, had low output voltage on U7 and U33 has a high failure rate.. both were same part#, I bought them from Digikey and even got extras since they were so cheap. After replacing them the TV now powers on and works fine.
                        Had the same happen with another 42 inch vizio (vw42l) and ended up doing the same thing after it still had issues after replacing u33. Been working 3 months now.

                        Comment


                          #13
                          Re: VIZIO VX37L No picture or sound.

                          Fixed. Replaced U33 and U7

                          Comment

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