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Vizio M801D-A3 backlights flicker

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    Vizio M801D-A3 backlights flicker

    Need a little help here.


    the backlights flicker when watching tv. Everything else works as it should. Also it's not the picture that's flickering just the leds.

    I tested the leds and all light up and measure 77.5v volts. I took the tv apart to double check leds and they all work and light up perfectly.

    I believe it's the power board causing the issue however I cannot find a replacement board so I'm stuck to finding the bad component. The power board has a sizzling sound coming from the backlight transformer. I replaced that and problem persist. Also replaced the film capacitor next to it and that seemed to help with the sizzling noise but not completely and still flickers a little bit.

    All voltages on the led driver board are steady and do not fluctuate.

    Looking for some advice on what to troubleshoot next.


    Thanks in advance
    Attached Files
    Last edited by Storyteller12; 05-25-2021, 11:37 AM. Reason: Added pics

    #2
    Re: Vizio M801D-A3 backlights flicker

    Ok,
    Quick update. It's definitely the power board causing the problem.

    When I lift the board the flicker gets worse and if I set it back down its not as bad. I'm not sure what's short but I have tried re-soldering some of the main areas but still the flickering occurs. The whole board looks like it's cold soldered from the factory. I will definitely re solder some more areas,
    But here is a picture of the back of the board if someone sees something else please let me know.

    Thanks
    Attached Files

    Comment


      #3
      Re: Vizio M801D-A3 backlights flicker

      You might want to check all the grounding points, usually the screw mounts to ensure they are clean and tight.

      Comment


        #4
        Re: Vizio M801D-A3 backlights flicker

        Thanks for the suggestion. I did check that after posting just to make sure. Even re soldered the contact points to make sure there was good contact. I think we are on the right track just can’t narrow it down.

        Unfortunately same flickering occurs.

        Comment


          #5
          Re: Vizio M801D-A3 backlights flicker

          I have the same exact model TV with the same backlight flickering problem and the transformer noise. I am an electronics engineer and have an oscilliscope an plan to open the TV and do the repair. I also can't find a replacement power supply board. I am very interested to see if you have had any success repairing yours. Any additional insight would be greatly appreciated.

          Comment


            #6
            Re: Vizio M801D-A3 backlights flicker

            I’m still troubleshooting it. Haven’t had much time lately with work. Not sure you oscilliscope will help with this. It seems to be a short somewhere. Haven’t pinpointed off it’s a grounding issue or a short on the power side yet.
            I’ll keep you posted with any updates and you do the same. 2 heads working on it is better than 1. Plus all the great help from everyone on the forums.

            Comment


              #7
              Re: Vizio M801D-A3 backlights flicker

              Smeaton111, any progress on this? I still can’t track down the issue, but I at least have time to troubleshoot it again.

              Comment


                #8
                Re: Vizio M801D-A3 backlights flicker

                No luck yet. I also haven't had much time to look into it. Where did you find the transformer? Did that take care of the aching sound entirely? I searched for the transformer model number online but didn't find anything. Is it possible to get schematics or a service manual for it. I just now saw your two posts.

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