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Vizio VX42LHDTV10A stuck in standby after going haywire.

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    #1

    Vizio VX42LHDTV10A stuck in standby after going haywire.

    Ok folks,been reading for the last 3 hours and could use a little guidance.I have a unit that went completely haywire last night.It displayed horizontal multicolor lines and was making a terrible squealing through the speakers and would not respond to any button presses.It had to be unplugged to make it stop.

    After letting it sit for about an hour,I plugged it back in and get the orange Vizio logo and nothing else.No response to buttons,or remote.Just an orange vizio logo.

    After reading the forums,I have found some good advice on where to start looking,but so far have found nothing definitive.I work in car audio and security and have a decent electronics background.Im proficient with a multimeter and am completely comfortable testing anything you guys can point me towards.

    I have visually inspected every capacitor in the tv and nothing has ruptured or shows any sign of buldging.This model has the singal long inverter board and the capacitors look good there as well.I have also tried powering on the unit with the inverter board unplugged and still no dice.It just wont do anything.

    I tested all the outputs on the power supply and the only thing that actually has output are the 5V lines.Is this normal?

    If anyone has any ideas on where to go from here,Im all ears and look forward to hearing from you all.

    MODEL- VX42L HDTV10A
    Serial LSABMBH4614174
    Date of Manufacture 11-07
    Part Number 10235030022

    Tags: None
    #2
    Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

    1) Post clear focused top down view pictures of all your boards following the instructions in my sig file below EXACTLY.

    2) 5V indicates that your standby is working.

    3) The main board should be sending a signal to tell the power board to turn on the SMPS. This signal is sometimes called PS_ON and is usually 3V or higher.
    --- 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

      #3
      Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

      That is the 5VDC Standby power supply, it always running, the other power supply sections (12v for the sound, and 24v for the backlights inverter) are controlled by the main board, the main board will send out the PS_ON signal to the power supply to turn them on when power switch is activated. Please post good clear pictures of the whole rear view of the TV so we can see how the boards are connected together, then good pictures of the power supply board both top and bottom sides, connectors so we can see the labels on them. There should be a pin with PS_ON (or PWR_ON), measure the DC voltage on that pin (black probe of the meter to the chassis) with the TV off and with the TV on.
      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 VX42LHDTV10A stuck in standby after going haywire.

        The main board is the one with all of the video connections I would say that if your TV is still indicating that it is powering on then it is likely that you need to replace this board look for things that may be bad on this board as well like a blown cap or something ... If not it is hard saying what it is look at the screen prints and check for blown fuses marked F in most cases... for instance F5 or F12 or F2 something along them lines do a continuity check some of these may not look like fuses but they are SMT variations of fuses. beyond that it gets kind of difficult to diagnose anyways good luck with your project.
        Please note: I am not responsible for any harm caused to you anything discussed is just discussion. Before you try anything discussed be sure that you have the appropriate knowledge and safety gear for the job. Like with anything education and safety are first! Do not try anything @ home without it.

        Comment

          #5
          Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

          Yea,all the fuses test under 1 ohm,so I assume (you know that that gets you) that theyre good.Also it seems that the larger heat sink on the power supply will provide you with a nice little 56v tingle when plugged in,is that normal?

          Sorry about the quality of pics,my phone is all I have
          Attached Files

          Comment

            #6
            Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

            Originally posted by ktulu909 View Post
            Also it seems that the larger heat sink on the power supply will provide you with a nice little 56v tingle when plugged in,is that normal?
            Heatsinks are live and can potentially be 400V DC depending on PFC or not. Don't touch them.

            On the power board, there is a PS_ON pin. When you press the on/off button, does this pin change from 0V to 3V or higher?

            If not, there are a ton of voltage regulators on the main board. You will have to measure them all to see if anyone are bad. Vizio's have a problem with voltage regulators failing.
            --- 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

              #7
              Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

              I have encountered the "going haywire and then not working problem before", but not on a Vizio (as they aren't sold in the UK.) It was on a cheap China-brand TV.

              It turned on a supply on the motherboard had failed while the user was watching, leaving them with a screen full of vertical coloured lines because the T-con board was not receiving a proper signal any more. When they tried to power it up after unplugging it, the power LED would come on but that was it... and then it wouldn't shut down again until unplugged.

              So I would carefully check all secondary supplies pn the motherboard especially the dreaded U33.
              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

                #8
                Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                Sorry for the lack of an update folks,Ill be going back over there tomorrow to look at a few more things and see if the power supply is receiving the signal to turn on and we'll go from there.

                What would be acceptable voltages on the the regulator pins on U33 and the other ones that look similar?

                Comment

                  #9
                  Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                  Originally posted by ktulu909 View Post
                  What would be acceptable voltages on the the regulator pins on U33 and the other ones that look similar?
                  If you are lucky, there distinguishable part numbers on each chip that reads something like 1117-33 where the suffix tells you the correct output voltage +/- 1%. So 1117-33 designates 3.3V +/- 1%.

                  The output pin is usually the middle pin.

                  If there are no part numbers, common output voltages are 1.8, 2.5, and 3.3. Anything that reads 2.9, 3.1, 3.5, etc is likely bad.

                  I suggest you list and measure them all. Measure all the pins except the fat tab.
                  --- 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

                    #10
                    Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                    SHould those pins be showing any kind of voltage in standby,considering thats all I have lol.Heading over tomorrow afternoon to work on it some more.

                    Comment

                      #11
                      Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                      Originally posted by ktulu909 View Post
                      SHould those pins be showing any kind of voltage in standby,considering thats all I have lol.
                      Standby 5V power is required in order for the main board to work.
                      --- 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

                        #12
                        Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                        OK here we go.


                        Looking at the regulators as the fat tab being the top,listing pins left to right.

                        U2- Part number
                        AMC1117
                        F0734F
                        PIN 1 2.03 VDC
                        PIN 2 3.28 VDC
                        PIN 3 5.10 VDC

                        U8 Part number
                        AMC1117
                        F0734F
                        PIN 1 2.02 VDC
                        PIN 2 3.26 VDC
                        PIN 3 5.12 VDC

                        U33 Part number
                        AMC1117
                        F0734F
                        PIN 1 2.02 VDC
                        PIN 2 3.26 VDC
                        PIN 3 5.10 VDC

                        U7 Part number
                        AMC1117
                        F0734F
                        PIN 1 0.00 VDC
                        PIN 2 0.71 VDC
                        PIN 3 3.27 VDC

                        U9 Part number
                        K1117S15
                        735
                        PIN 1 0.00 VDC
                        PIN 2 1.50 VDC
                        PIN 3 3.27 VDC

                        Well,there you have it.I hate to assume,but Im going to go out on a limb and say that U7 and U9 are bad.Now this is the part where you professionals tell me if im right or not lol.

                        Anything else you guys want me to check?

                        Oh and no,no voltage is showing on the PS_ON line when the power button is pressed.
                        Last edited by ktulu909; 03-20-2012, 04:12 PM.

                        Comment

                          #13
                          Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                          http://pdf1.alldatasheet.com/datashe...C/AMC1117.html

                          There is the datasheet for those regulators this will allow you to chack and see if they are in range or not.

                          Can you edit the numbers so we know what each line says? its hard to look at what they are with them in 1 big row as some of the numbers wont be relevant.
                          Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                          How to resize your pictures guide click HERE
                          Retiredcaps Ideal post example click HERE

                          Comment

                            #14
                            Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                            I appreciate you posting the datasheet,but unfortunately the info is a little out of my league lol.Ill stare at it for awhile and see if anything jumps out and I can put 2 and 2 together.

                            Comment

                              #15
                              Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                              Ok after looking at the datasheet for 15 minutes,I see that U7 and U9 are receiving lower voltage on the input pin than the others.Does that mean that my problem lies elsewhere before those two components?Or are those two regulators supposed to have a lower voltage on them?

                              Also,whats the significance,if any,of U9 being a different part number than the others?Also the datasheet doesnt show my specific part number (ending in 734) anywhere.

                              Ok,now im officially confused lol.

                              Comment

                                #16
                                Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                                They way they work is like this.

                                AMC1117 This is the part number F0734F is possibly underneath the part number im guessing? so this might be a date code.

                                If your part number was AMC1117-1.8 this would tell us that your should have 1.8v on Pin 2 which is out. If it was AMC1117-2.5 then pin 2 should be 2.5v.

                                So if you look at K1117S15735.... Part number K1117S with the next 15 meaning 1.5v on pin 2.

                                Does that make sense?
                                Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                How to resize your pictures guide click HERE
                                Retiredcaps Ideal post example click HERE

                                Comment

                                  #17
                                  Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                                  Originally posted by Jasgriff View Post

                                  Can you edit the numbers so we know what each line says? its hard to look at what they are with them in 1 big row as some of the numbers wont be relevant.
                                  Edited.There ya go

                                  Comment

                                    #18
                                    Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                                    Ok on Pin 1 of U7 are there 2 resistors connected to it?
                                    Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                    How to resize your pictures guide click HERE
                                    Retiredcaps Ideal post example click HERE

                                    Comment

                                      #19
                                      Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                                      Originally posted by Jasgriff View Post
                                      They way they work is like this.

                                      AMC1117 This is the part number F0734F is possibly underneath the part number im guessing? so this might be a date code.

                                      If your part number was AMC1117-1.8 this would tell us that your should have 1.8v on Pin 2 which is out. If it was AMC1117-2.5 then pin 2 should be 2.5v.

                                      So if you look at K1117S15735.... Part number K1117S with the next 15 meaning 1.5v on pin 2.

                                      Does that make sense?
                                      Thank you for the breakdown.That makes perfect sense on the K1117,but unfortunately not so much on the AMC1117 to me.Please be gentle,Im trying to soak all of this in.

                                      Comment

                                        #20
                                        Re: Vizio VX42LHDTV10A stuck in standby after going haywire.

                                        Originally posted by Jasgriff View Post
                                        Ok on Pin 1 of U7 are there 2 resistors connected to it?

                                        Yes there are,two microscopic resistors.

                                        Comment

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