Vizio M801D-A3 backlights flicker

[Storyteller12]

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

[Storyteller12]

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

[budwich]

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.

[Storyteller12]

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.

[smeaton111]

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.

[Storyteller12]

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.

[Storyteller12]

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.

[smeaton111]

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.