Vizio E420VL input problems

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  • Beowulf
    Senior Member
    • Dec 2012
    • 175
    • USA

    #1

    Vizio E420VL input problems

    Hi,
    This TV has problems with the input signals (the tv shows the "no signal" message when tuned to each of the inputs except composite video.). For some reason it's not processing it right. For example, none of the input interfaces work or work appropriately. None of the HDMI work. The AV analog, dont work neither. The composite video (Y pb/cb pr/cr) interface does display video normally, although it doesn't produce audio. Have not test the other input ports.
    I assume it has to do with the primary video processor chip on the motherboard, which in fact is a bga package.
    I tried my luck doing a light reflow, before doing a complete reflow, of the chip at about 200c to see if it'd help but it didn't make a change.

    Other than checking the fuses and looking for any visual damage I have not tried anything else.

    It's this board here (3642-0872-0150):
    https://www.shopjimmy.com/vizio-3642...for-e420vl.htm

    Here is a picture of what's under the heat sink.
    Attached Files
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Vizio E420VL input problems

    Have you tested all the voltage regulators feeding? One faulty could cause a partial loss of functionality.
    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

    • Beowulf
      Senior Member
      • Dec 2012
      • 175
      • USA

      #3
      Re: Vizio E420VL input problems

      Hi @tom66,

      I spent quite sometime today learning how to check voltage regulators from this post here:
      https://www.badcaps.net/forum/showth...391#post274391

      This is what I found.

      I checked 7 different voltage regulators I found on the board, of which 4 were 1117 adjustables. Of these, two (U2 & U7) are not providing too favorable output voltages (3.28, 3.30 respectively, where they should be 3.55, 3.85).

      The reference voltage between adj/gnd and out pin is 1.22v on some and 1.23v on others.

      In conclusion based on my understanding these two regulators need replacing, if there is something I'm missing please let me know.

      Regards,

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Vizio E420VL input problems

        "two (U2 & U7) are not providing too favorable output voltages (3.28, 3.30 respectively, where they should be 3.55, 3.85).

        The reference voltage between adj/gnd and out pin is 1.22v on some and 1.23v on others."

        So if you add the 1.25v to what you read on pin1, the numbers come out wrong for U2 and U7 at pin 2 reading?
        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

        • retiredcaps
          Badcaps Legend
          • Apr 2010
          • 9271

          #5
          Re: Vizio E420VL input problems

          Post the results like

          AS1117-33 -> line 1 of the IC
          0506 -> line 2 of the IC
          pin 1 = 0.000
          pin 2 = 3.301
          pin 3 = 5.001

          so it is easy for us to read and interpret.
          --- begin sig file ---

          If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

          Please do not post inline and offsite as they slow down the loading of pages.

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          Comment

          • Beowulf
            Senior Member
            • Dec 2012
            • 175
            • USA

            #6
            Re: Vizio E420VL input problems

            budm, Yes.

            Here more details.

            U2
            1117

            Pin 1 = 2.3v
            Pin 2 = 3.28
            Pin 3 = 5.19
            Reference voltage 1.23v


            U7
            1117

            Pin 1 = 2.6v
            Pin 2 = 3.30
            Pin 3 = 5.15
            Reference voltage 1.22v
            Last edited by Beowulf; 02-01-2013, 06:08 PM.

            Comment

            • Beowulf
              Senior Member
              • Dec 2012
              • 175
              • USA

              #7
              Re: Vizio E420VL input problems

              My bad retiredcaps, your post came when I was getting my last post ready.

              I'll put it together that way if it's still not clear.

              Comment

              • retiredcaps
                Badcaps Legend
                • Apr 2010
                • 9271

                #8
                Re: Vizio E420VL input problems

                Let's see a clear closeup picture of U2 and U7 and their surrounding components.
                --- begin sig file ---

                If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                Please do not post inline and offsite as they slow down the loading of pages.

                --- end sig file ---

                Comment

                • Beowulf
                  Senior Member
                  • Dec 2012
                  • 175
                  • USA

                  #9
                  Re: Vizio E420VL input problems

                  Here, as I posted above is the best way.
                  https://www.shopjimmy.com/vizio-3642...for-e420vl.htm


                  Up by the top right corner of the heat shield.

                  Comment

                  • retiredcaps
                    Badcaps Legend
                    • Apr 2010
                    • 9271

                    #10
                    Re: Vizio E420VL input problems

                    Referring to someone else's photos is like going to a heart surgeon for emergency surgery with your mother's xrays.
                    --- begin sig file ---

                    If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                    We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                    Please do not post inline and offsite as they slow down the loading of pages.

                    --- end sig file ---

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #11
                      Re: Vizio E420VL input problems

                      I spot more than U2 and U7 on that board; have you tested ALL of them?
                      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

                      • Beowulf
                        Senior Member
                        • Dec 2012
                        • 175
                        • USA

                        #12
                        Re: Vizio E420VL input problems

                        Haha!


                        tom66,
                        Yeah as I mentioned above, they were spot on.

                        Comment

                        • Beowulf
                          Senior Member
                          • Dec 2012
                          • 175
                          • USA

                          #13
                          Re: Vizio E420VL input problems

                          U4
                          1117

                          Pin 1 = 0v
                          Pin 2 = 1.22
                          Pin 3 = 3.29
                          Reference voltage 1.22v

                          U46
                          1117

                          Pin 1 = 2.0v
                          Pin 2 = 3.25
                          Pin 3 = 5.15
                          Reference voltage 1.22v

                          U8
                          MC7805CT
                          RAB014G

                          Pin 1 = 12.24 (in)
                          Pin 2 = 0 (ground)
                          Pin 3 = 5.1 (out)

                          TU5
                          M113
                          G1084

                          Pin 1 = 0.57v
                          Pin 2 = 1.81
                          Pin 3 = 3.26

                          U3
                          M113
                          G1084

                          Pin 1 = 2.04v
                          Pin 2 = 3.30
                          Pin 3 = 5.15

                          Comment

                          • Beowulf
                            Senior Member
                            • Dec 2012
                            • 175
                            • USA

                            #14
                            Re: Vizio E420VL input problems

                            Alright, Here hope it helps.
                            Attached Files

                            Comment

                            • retiredcaps
                              Badcaps Legend
                              • Apr 2010
                              • 9271

                              #15
                              Re: Vizio E420VL input problems

                              Measure and report the resistance of R34 and R35.

                              Then have a look at budm's spreadsheet in

                              https://www.badcaps.net/forum/showpo...17&postcount=6
                              --- begin sig file ---

                              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                              Please do not post inline and offsite as they slow down the loading of pages.

                              --- end sig file ---

                              Comment

                              • Beowulf
                                Senior Member
                                • Dec 2012
                                • 175
                                • USA

                                #16
                                Re: Vizio E420VL input problems

                                U2
                                R34 is 98.5, R35 is 148.2

                                U7
                                R44 is 109.7, R45 is 183.4.

                                Right, I'll take a look at that spreadsheet.

                                Comment

                                • Beowulf
                                  Senior Member
                                  • Dec 2012
                                  • 175
                                  • USA

                                  #17
                                  Re: Vizio E420VL input problems

                                  So,
                                  Based on that spreadsheet, I should be getting 3.131v on pin 2 (Vout) of U2, and I'm actually getting 3.28, would this be considered bad, what is the tolerance? 2%?

                                  On the other hand,
                                  U7 results are now favorable based on the calculations from that spreadsheet.
                                  Calculated Vout is 3.340, where I'm actually getting 3.30.

                                  Comment

                                  • tom66
                                    EVs Rule
                                    • Apr 2011
                                    • 32560
                                    • UK

                                    #18
                                    Re: Vizio E420VL input problems

                                    3.3V is a typical output voltage, and 3.28V is close enough.
                                    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

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #19
                                      Re: Vizio E420VL input problems

                                      That U2 readings of the resistance can be affected by the circuit resistance that are being seen by the output pin. I would think it is more likely to have 3.3V out, which is the typical output voltage.
                                      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

                                      • Beowulf
                                        Senior Member
                                        • Dec 2012
                                        • 175
                                        • USA

                                        #20
                                        Re: Vizio E420VL input problems

                                        I have a scope in case anybody wanna provide some guidance on how to check for the signals coming from the hdmi interface chip, the main graphics processor, the lvds interface chip etc.

                                        Comment

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