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    Vizio M50-C1 will not power on

    Does anyone have schematics for any of the boards in the Vizio M50-C1?

    I am unable to power on the TV. I can see a blue-ish LED illuminated, located on the back just behind the Ethernet connector. I assume this is the main board.

    Checking voltages on the power supply board seems to show some odd values. On CN9101 (image attached) when the power is expected to be off/standby the voltage on the "5v" lines is 5.1v as expected, but the 12v lines are reading around 19.1. That seems to suggest PS board issue, but I'm not convinced yet.

    Thoughts?
    Attached Files

    #2
    Re: Vizio M50-C1 will not power on

    you need to post pictures of the back layout so the forum can see how things are connected.

    Further, depending on how things are connectecd, the 12v line may go to the main board to be switched to the tcon or go directly to the tcon. It would appear that the 12v is "open circuit valued" based on your measurements... this means an issue at the "destination" which you need to check.

    Still further, besides the "labeled voltages", the values of the other labels (usually controls) are important so you need to check those. Note: some are "active" during initialization / power up and may disappear shortly there after if the system detects issues so you need to monitor them during the whole attempt from standby to power up to watch for changes.

    Comment


      #3
      Re: Vizio M50-C1 will not power on

      Thank you for your reply.

      I realize that the 19v is an indication of an "open" somewhere. The problem is that without a flow chart or schematic, it seems difficult to determine if the open is on the source side or the destination side. It appears that I cannot get accurate readings if I disconnect the PS board from the Main board, so that's making it a bit more difficult (at least for me).

      I have added a picture of the entire back.

      If it matters, the serial number starts with: LTM6SRAR
      Attached Files

      Comment


        #4
        Re: Vizio M50-C1 will not power on

        It would be nice if schematics were available but you can still do a lot without them.
        Your picture obviously shows that the 12v supply is switched by the main board to get sent to the tcon... as there is no direct connection from the power supply to the tcon.

        So you need to trace the connection at the main to see where the 12v gets to in the main card... follow the track... you don't need the actual voltage at this point. Of course, checking the fuse at the tcon board is needed.

        Further, as suggested, measure the labeled pins as suggested in standby and with power on... don't disconnect anything at this point.

        Further, as you may know some designs, allows you to disconnect the main from the ps and get backlights... but not all designs follow this. There are "jumper techniques" to cause the power supply to turn on without the main control board.... involves jumpering with a resistor to provide the ps-on signal to the appropriate pin.

        Further, since you are getting some voltages, it is likely that you have a proper ps-on signal but that and other control pins should be checked to confirm and determine.
        Last edited by budwich; 11-13-2018, 11:08 AM.

        Comment


          #5
          Re: Vizio M50-C1 will not power on

          I've confirmed the wiring between the Main and PS board is good. I do not see any obvious fuse on the Tcon board.

          There are obvious signs of component damage either. I guess the real question is whether that 12v is coming into the PS board or supposed to be going out? If I understood that, it might be easier to narrow this down. I suppose I could look for the same 19v component by component. That would get me in the neighborhood (I think).

          I'd like to avoid doing shotgun repair and replace everything. I don't mind if I can't identify the specific component and have to replace an entire board, but would rather not replace them all just because I couldn't narrow it down.

          Comment


            #6
            Re: Vizio M50-C1 will not power on

            There is a fuse somewhere on the tcon. (FXXX or something).

            Further, the 12v is coming out of the PS. It is sent to the main to be switched to the TCON as required.

            As suggested, you don't need power on the set to trace the wiring / tracks ... use the resistance scale on your meter (and if capable select the audible / short test mode) and go from the PS thru to the corresponding wiring to the main. Then when you get to the main, move from that connector into the board looking closely at the tracks (yes the might be hard to see... but that why you then use the meter to find the path there).
            Eventually, you will likely come to a FET / IC that the board controller switches on/off when required to send the voltage on to the TCON. Potentially that "FET" maybe blown. Go from there.
            Last edited by budwich; 11-13-2018, 05:58 PM.

            Comment


              #7
              Re: Vizio M50-C1 will not power on

              Right now the main board is not sending the BL-ON (ON/OFF) either.
              Try disconnecting the WIFI module and see what happen.
              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


                #8
                Re: Vizio M50-C1 will not power on

                Disconnecting the wifi board makes no difference (behavior is the same). I think the hint here is the 19v measured at the output side of the PS board. I'm fairly certain this suggests a bad component on that board. I've rarely seen a case where a power supply would show signs of an "open" when not connected to the boards to which they were meant to power. Generally I would expect a PS to be able to operate standalone.

                I think I will order a replacement PS and see what happens.

                Comment


                  #9
                  Re: Vizio M50-C1 will not power on

                  Power supplies voltages will "drift" higher when not under load. measure the resistance on the pin of the cable when it is disconnected from the board to see what the power supply is driving.
                  Last edited by budwich; 11-14-2018, 12:35 PM.

                  Comment


                    #10
                    Re: Vizio M50-C1 will not power on

                    To close the loop for anyone with similar symptoms as I described, the issue was in the main board. Helpful symptom was that in the bad case the LED on the main board was lit blue. Once I replaced the bad board the LED now is red. So this must be a status light of some kind. It sure would be nice if someone had the details of what each color means.

                    Anyway, my TV works again with a main board replacement. Thank you shopjimmy.com

                    Comment


                      #11
                      Re: Vizio M50-C1 will not power on

                      Thanks for feedback on the repair.
                      So the 12V is now 12V?
                      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


                        #12
                        Re: Vizio M50-C1 will not power on

                        Yes, all voltages appear as expected now. If I manage to get my hands on some official Vizio docs that explain the LED colors, I will post that info.

                        Comment


                          #13
                          Re: Vizio M50-C1 will not power on

                          Hey guys,

                          bumping this, hope thats ok. I picked up this same exact TV (M50-C1), nearly the same exact problem. No power, no backlight, no audio & no visual but the LED on my mainboard acts correctly. I also have 19v on some pins labeled as 12v on the PSU.

                          I've tried to replace the mainboard with another supposedly working one with proper serial cross-referencing and it still wont power on - but there is one difference - on the original mainboard, the external LED would power on then fade out (normal act for this vizio i guess) but on the new mainboard, it blinks 20 times or so.

                          On a whim I purchased a pre-programmed eeprom from ShopJimmy for my original mainboard, replaced it properly and no change. same issue.

                          Any suggestions on what to check next? I still feel like its a mainboard issue but would've though a new one should've solved it. The rest of this set is flawless visually.

                          Comment


                            #14
                            Re: Vizio M50-C1 will not power on

                            Hello,
                            I need your help to troubleshoot my Vizio M50-C1 led TV. It is having blank screen. I check My power board is generating stable voltages(19.06 V & 22 V) going to led driver boards and mainboard. backlight also lights of for few seconds and shuts down. Tcon is getting 12v supply from the mainboard. fuse on TCON board is good.

                            I disconnect one side of the ribbons that is connected from the lcd to driver board i get a picture on the half of the screen but when I connect both side back there is no picture at all. system shuts down in seconds.

                            I found one of the COF ic gets really hot. I checked the SMD caps they show short with lcd driver board disconnected from TCON . I took out all smds cap to check which was showing short but it was not short off the board. there were 6 cofs on that side of the driver board. It seems like the short really coming from lcd panel. Please help.. Thanks

                            Comment


                              #15
                              Re: Vizio M50-C1 will not power on

                              Are you getting a perfect picture on half the screen with either side ribbon disconnected? As in no lines running thru horizontally __ __ or distortion of any type?
                              Last edited by nomoresonys; 01-29-2020, 09:25 AM.

                              Comment


                                #16
                                Re: Vizio M50-C1 will not power on

                                Does your hot cof look burnt or different than the rest?

                                Comment


                                  #17
                                  Re: Vizio M50-C1 will not power on

                                  Does this tv have tabs on both sides of the tv? That's left and right NOT top and bottom.

                                  Comment


                                    #18
                                    Re: Vizio M50-C1 will not power on

                                    Yes ... left side picture is perfect no lines no color issues.
                                    All COF looks normal no burnt and solid bonded.. no flickering. It has no gate driver or side COF. only at the bottom it has 6 COFs.

                                    Comment


                                      #19
                                      Re: Vizio M50-C1 will not power on

                                      backlight stays on but dims out... LED on mainboard show purple and blue mix lights on.

                                      Comment


                                        #20
                                        Re: Vizio M50-C1 will not power on

                                        TV shuts off as soon as you plug in both ribbon to TCON ... definetely short coming from left side of the lcd panel ? Caps show short

                                        Comment

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