vizio VW42L voltage too high help

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  • marlboroa
    Senior Member
    • Jul 2012
    • 59
    • USA

    #1

    vizio VW42L voltage too high help

    Hello, I have a Vizio VE42L that im trying to fix. It does not have sound, picture or backlight. I can turn it on at the side panel and the light will go from amber to white. I can not turn it off. it has to be unpluged.
    I have tested the output voltage at the power supply and they seem way to high.

    My 5 volt reads 7 almost 8
    12 volt reads 18
    24 volt reads 37-38

    were should i start checking? I dont see any capacitors that "look" bad but they could be. could anything on the main board or t-con board make the voltage this high? I also checked the incomming voltage at the fuses on the main board and they both read 7 volt. Any help would be a big help.
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: vizio VW42L voltage too high help

    Did you verify the meter by measuring a batteries, just to be sure. Also check the meter's batteries.
    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

      #3
      Re: vizio VW42L voltage too high help

      It would also help if you posted the make and model or a picture of your multimeter.
      --- 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.

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      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: vizio VW42L voltage too high help

        Very common with cheaper meters to measure too high a voltage when running on a low battery.

        Notice they're all about 50% higher than they should be.
        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

        • marlboroa
          Senior Member
          • Jul 2012
          • 59
          • USA

          #5
          Re: vizio VW42L voltage too high help

          I'll change out the battery tomorrow as I did notice that the beeper is sounding weak. It's been a good meter to me. I do a lot of pinball repairs and it has not failed me yet. I really need to buy a ESR.

          Comment

          • marlboroa
            Senior Member
            • Jul 2012
            • 59
            • USA

            #6
            Re: vizio VW42L voltage too high help

            ok changed out my meters batteries and everything looks alot better.
            comming out of the power supply i have
            25.1 volts
            12.36 volts
            5.17 volts


            I checked the volts at the fuses on the main board and got 12.47 at F1 and 5.15 at F2
            then i checked the u chips on the main board. these readings are from top to bottom.

            U2
            2.12
            3.28
            2.03

            U7
            3.27
            1.01
            0.02

            U8
            5.15
            3.28
            2.03

            U9
            3.27
            1.50
            0.00

            U33
            5.12
            3.27
            2.02


            What do i check now? It would seem that U9 and u7 are bad?
            Attached Files
            Last edited by marlboroa; 07-31-2012, 02:54 PM.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #7
              Re: vizio VW42L voltage too high help

              What are the part #s for each of the "U" chips?
              e.g. LM1117-18 indicates a 1117-type regulator, 1.8V output, made by National Semiconductor ("LM".)
              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

              • marlboroa
                Senior Member
                • Jul 2012
                • 59
                • USA

                #8
                Re: vizio VW42L voltage too high help

                U2, U7, U8, U33 are all AMC117
                U9 is a K117s15

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #9
                  Re: vizio VW42L voltage too high help

                  No number after AMC1117?
                  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

                  • marlboroa
                    Senior Member
                    • Jul 2012
                    • 59
                    • USA

                    #10
                    Re: vizio VW42L voltage too high help

                    AMC117 F06461 Maybe? its very hard to read and i tried to get a good pic of it.
                    the other one is K117s15 612
                    Attached Files

                    Comment

                    • marlboroa
                      Senior Member
                      • Jul 2012
                      • 59
                      • USA

                      #11
                      Re: vizio VW42L voltage too high help

                      i have .15 on either side of the fuse on the t-con board if that helps any. the inverter light is not on either. I did try this

                      Originally posted by XmouseX
                      Dont know if this matters, bu I just jumped 5V to pin 13 on J1 and the backlight came on....I will do the tests that you suggested. Thank you
                      when i jumped it my backlight came on too.
                      Last edited by marlboroa; 07-31-2012, 05:48 PM.

                      Comment

                      • Mr Bill
                        Badcaps Veteran
                        • Nov 2011
                        • 648
                        • USA

                        #12
                        Re: vizio VW42L voltage too high help

                        Originally posted by marlboroa
                        What do i check now? It would seem that U9 and u7 are bad?
                        U9
                        3.27
                        1.50
                        0.00

                        U7
                        3.27
                        1.01
                        0.02

                        U9 is good. It's outputting 1.5v K117s15

                        U7 is bad. It should be outputting 1.8v and it's only giving you 1.01v

                        I repaired a GV42L that had a bad regulator and the bulbs didn't turn on until that regulator was replaced. It was getting 24v all the way to the master and slave inverter.

                        Comment

                        • marlboroa
                          Senior Member
                          • Jul 2012
                          • 59
                          • USA

                          #13
                          Re: vizio VW42L voltage too high help

                          ok i have a spare board set from another tv. it has the following parts.

                          AMS117 0618
                          AMS117 1.8 0623
                          AMS117 3.3 0621

                          Can i use the AMS117 1.8 as a replacement for U7

                          Comment

                          • Mr Bill
                            Badcaps Veteran
                            • Nov 2011
                            • 648
                            • USA

                            #14
                            Re: vizio VW42L voltage too high help

                            U7 is an adjustable regulator so you would need to replace it with an adjustable regulator. The first one in your list is an adjustable 1117 regulator. If it had a -33, -18, -25 it would be a fixed regulator.

                            Comment

                            • marlboroa
                              Senior Member
                              • Jul 2012
                              • 59
                              • USA

                              #15
                              Re: vizio VW42L voltage too high help

                              ok so i can use the first one on the list. I have alot of them. should i change the caps around u7 while im there?

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #16
                                Re: vizio VW42L voltage too high help

                                No need to change the caps for now. They are under much less stress than other parts.
                                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

                                • marlboroa
                                  Senior Member
                                  • Jul 2012
                                  • 59
                                  • USA

                                  #17
                                  Re: vizio VW42L voltage too high help

                                  i changed out U7 for the one that i had. TV works perfect now. Thanks for all the help and ill have plenty more tv's to fix. for some reasone they only last about 3-4 years.

                                  I only asked about the caps because on some of the pinballs that i fix if you dont change out certian capacitors then you will blow a new transistor. Its wierd how they work.

                                  Again thanks to all who helped.

                                  Comment

                                  • marlboroa
                                    Senior Member
                                    • Jul 2012
                                    • 59
                                    • USA

                                    #18
                                    Re: vizio VW42L voltage too high help

                                    ok not completly fixed yet. I can not get either HDMI or red, yellow,white, inputs to work. It does display the Vga input great. what should i look at now or do i have a 42" computer monitor?

                                    Comment

                                    • marlboroa
                                      Senior Member
                                      • Jul 2012
                                      • 59
                                      • USA

                                      #19
                                      Re: vizio VW42L voltage too high help

                                      ok i got vga and av 1 and 2. I can not test componet but i can test the HDMI and i dont have either of them. they just display random stuff. sometimes grey lines. sometimes colors just random stuff.

                                      Comment

                                      • tom66
                                        EVs Rule
                                        • Apr 2011
                                        • 32560
                                        • UK

                                        #20
                                        Re: vizio VW42L voltage too high help

                                        Check your replacement regulator is giving 1.8V. Also, check if there are any other regulators, maybe one powers the HDMI and it is giving problems.
                                        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

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