Vizio M3D550KD saturation fluctuation?

[elemdai]

Hi everyone,

I recently got a Vizio M3D550KD for $60(!) off CL. The issue the previous owner didn't know how to fix was that as soon as you plugged in the TV, it would boot up to the Vizio logo and then boot loop to that point until you unplugged it. I replaced the main board and the power supply board and now it's running like a champ. With one exception. Now, regardless of input, the screen (mostly the right side, but there's no defined edge) the screen goes back and forth between what I would describe as full and partial saturation (see YouTube link for example). To my knowledge the only relevant board left to replace is the LED driver board, but I don't have enough experience to know for sure. I've factory reset and set it up from square one, but that didn't help. Hoping one of you guys can help!

Thanks

Video link: http://youtu.be/DM9OumrMBCE

[tom66]

Re: Vizio M3D550KD saturation fluctuation?

Could you try a test; on a full black screen you should see a slight glow, does it glow vary when the fault occurs (you'll usually need to be in a darkened room to tell), or is it only visible on an actual image?

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

It seems to be visible only on an actual image. I didn't see any fluctuations with just a black screen. I can upload a video if it would help.

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

It seems to be visible only on an actual image. I didn't see any fluctuations with just a black screen. I can upload a video if it would help.

Sorry for the double-post.

I've attached a comparison picture as well as pics of the T-Con and LED driver boards. I don't know if any of this helps, but I'm at the mercy of the internet right now. Thanks again.

[tom66]

Re: Vizio M3D550KD saturation fluctuation?

It is an odd fault. I would be tempted to say an issue with the LEDs but I would expect the black level to vary as well. And you say it does not. Does the white level vary? (Put the TV on all white - does white vary in intensity?) I suppose there's a small chance the LCD panel is bad... but it would be a first, never seen anything like this, so I doubt it myself.

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

I tried it with all white and forgot to take a picture, but it was TERRIBLE with that screen. No difference at all in black, but it was roughly the upper right third of the screen with white. It almost turned brown. Again, I'm no expert, but it seems to me that if the panel were bad that it wouldn't be rhythmic like it is. It seems like it would just stay bad. Am I wrong there?

[tom66]

Re: Vizio M3D550KD saturation fluctuation?

We have seem rhythmic faults be panel failures before... but I have NO idea what causes them... thinking it might be some kind of thermal expansion cooling and warming... white going brown sounds just like what we've seen before regarding failures of other panels. Is the motion in the failed half blurry at all, or is it OK?

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

The motion is fine. There's the discoloration and you can see some horizontal lines more clearly, but that's it.

[Alastair E]

Re: Vizio M3D550KD saturation fluctuation?

Sounds like a sorta inverse Mura effect!

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

I could always try loosening the front panel screws to see if that changes anything. I have a bit of Mura going on anyways, so it can't hurt to see if it fixes one or both problems.

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

Is it worth trying replacing either the TCon or LED driver boards?

[Alastair E]

Re: Vizio M3D550KD saturation fluctuation?

Worth checking the supply voltage to the LED's while its on a stationary image and performing its faults....

IF they are stable--then the LED driver/PSU is probably fine, and might be worth looking at the T-Con.

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

My abilities to check voltages are more than rusty. I just bridged a connection on my led board that shouldn't have been bridged. For better or worse, the TVs condition hasn't changed.

I've attached a picture that shows some lines and botching that is visible when not viewing the set straight on or during dark scenes. I have no idea if this could be caused by the same failing component(s) or if it is completely unrelated.

Honestly I'm willing to just replace a board rather than fiddle with figuring out where the fault specifically comes from since I seen incapable of even checking supply voltages. I just don't know which board is more likely or how to test without a multimeter.

Edit: None of this is meant to sound ungrateful to either of you. I appreciate your help. I'm just frustrated.

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

So, none of the caps looked bad on the LED driver board, but for kicks I replaced them. That didn't change things one way or the other. Are there any other tests I can do to see if the panel itself is going bad? I've read the stickied troubleshooting guides, but either I'm dense or I've gone as far as they'll take me. I don't want to give up on this TV just yet, it was such a bargain!

[elemdai]

Re: Vizio M3D550KD saturation fluctuation?

Checked the supply voltage on the LED board several times. Always comes in at 24.3. Thoughts?