Backlight rare white rings. Samsung 50in 4K TV

[pablo712]

Re: Backlight rare white rings. Samsung 50in 4K TV

I uploaded a video with hard plastic diffuser only; pressing it and lifting it
Could we conclude that the problem is the leds or the lens?

https://vimeo.com/321624748


And this is a real life video; rings are noticed in clear background. Always appear in sky, very anoying
https://vimeo.com/321629946

[chrismurphy]

Re: Backlight rare white rings. Samsung 50in 4K TV

the fault is the LED strips .only replacement will fix

[Diah]

Re: Backlight rare white rings. Samsung 50in 4K TV

before you going to replace strips. post clear photo on your tv boards and specialy the power board where it out put socket to led. last photo u posted it show the ring reflection you have it with out diffuser .it may lead us to reason low currents going to leds

[DXseekerMO]

Re: Backlight rare white rings. Samsung 50in 4K TV

Looks like dirty/obscured diffuser lenses to me

[gabiz_ro]

Re: Backlight rare white rings. Samsung 50in 4K TV

In one case for me,on LG,same lens type,something similar after replacing some led’s.
But problem was too for some untouched led’s.
Since no way to fix it I replaced all led’s and lens with problem,result was OK.

On those with problem I can see something like fog or smoke in lens.But no way to clean them.
What I say,some lens was crystal clear,all OK
Some others looks strange,like fog or smoke inside,no matter how I try to clean,no result and result was rings or spots in backlight.

Some of led’s are blue already,replace strips and solve problem.

[nomoresonys]

Re: Backlight rare white rings. Samsung 50in 4K TV

Ok, looks like all the time that these backlights were maxed at 20, ruined/prematurely aged the lights and the lenses, will probably be seeing a lot more of this.

[Unspun01]

Re: Backlight rare white rings. Samsung 50in 4K TV

For davph: I vape with an e-cigarrete; but very few times inside the house. What could happen with that?

Well you've seen what it did to your TV, just imagine how bright your lungs are...lol

Just kidding.

[Unspun01]

Re: Backlight rare white rings. Samsung 50in 4K TV

I think the only thing left to do is change the whole 6 strips of leds… I only found a workshop that sell those “used” from a broken screen TV at u$s 60 with no refund…

The size of the "rings" is directly related to the "light scatter pattern" of the lenses, rather than the size of the actual lens itself.

I have seen this style of larger "cylindrical" lens used in both LG and Samsung LED TVs, but I have never seen such a "ring" effect.

As much as I hate to say it, I think the LED "lenses" are faulty.

In the picture with no diffusers where we can see all of the individual LEDs and lenses, some appear to have a different (more blue) color.

By comparison, in the picture with the diffusers in place, the LEDs that are more "blue" have a less pronounced ring effect through the diffuser sheets. It looks like the lenses are bad.


Possible repair options:

You may try to pop off a few of these larger "cylindrical" lenses and try to replace with smaller "convex" lenses. By replacing a couple of cylindrical lenses with convex lenses, you can probably see an immediate effect.

See the attached photos for examples of the different lens I refer to.

I don't think the LED strips need to be completely replaced... Only the lenses (which is cheap but a lot of work). You can get 100 pieces on eBay for less than $5. The replacement lenses can be crazy-glued in place but make sure you directly center each lens over the center of the LED or you will get weird scatter patterns.

[Unspun01]

Re: Backlight rare white rings. Samsung 50in 4K TV

Also, since you have the TV flat on it's back, please try a test for us to satisfy my curiosity...

1) Cut a few strips of WHITE paper 20mm wide by 120mm long.

2) Form a loop with the paper and use a piece of clear scotch tape to tape the two 20mm ends together.

3) Place the paper loops around a few of the LED lenses and re-install the diffuser sheets and turn the TV on. Please report back with a photo of the backlight appearance.

You may try it with a few different colors of paper or different materials.

[nomoresonys]

Re: Backlight rare white rings. Samsung 50in 4K TV

If the lights are blue, they need replaced.

[William1967]

Re: Backlight rare white rings. Samsung 50in 4K TV

In picture 20190305_192113.jpg I see 9 blue leds, replace the led strips. After replacing adjust the backlight down to around 60%.

[pablo712]

Re: Backlight rare white rings. Samsung 50in 4K TV

Well, problem is solved!!! I think the root cause was worn leds because of backlight setting 20/20 for over 2 years..
I finally bought all 6 led strips from as “used” retired from another tv with screen broken (I didn't found where to buy brand new strips)
The strips are exactly same model as my TV has, and they came with same kind of lens attached
The new strips when turned on didn't look too different to my old ones; I mean were not noticeable change in light power but the new strips don't have blue leds obviously.
I didn't take photos without diffusers and with both kind of strips mixed, I just attached two photos; one with hard plastic diffuser only (some irregularities but rings disappeared) and one with all the diffusers (a very good distributed white)

Thank you for all your help; You help me to troubleshot different possible causes and discard them.
Now I set the backlight to 11/20 😊

[nomoresonys]

Re: Backlight rare white rings. Samsung 50in 4K TV

Nice work

[budm]

Re: Backlight rare white rings. Samsung 50in 4K TV

Thanks for the follow-up, it looks like the new LENS style will be lots of problem in the future beside bad LED's.

[nomoresonys]

Re: Backlight rare white rings. Samsung 50in 4K TV

If the lights are blue, they need replaced.

Meaning they should all be replaced, it's a phosphor thing, the ones that aren't blue will most likely be blue very shortly.

[arenat]

Re: Backlight rare white rings. Samsung 50in 4K TV

Same here with an LG , they are putting the bare chip 15x15 integrated with the strip , over time the exposed phosphor worn out .The pic is from a new strip , two years half the diodos became blue .

[andrews7523]

Re: Backlight rare white rings. Samsung 50in 4K TV

Ive started seeing this on a few ku models now. Im not sure if the lenses are coming slightly loose as the LEDs are fine. Luckily for me a had donors but these Lenses used are like vestel which is strange for Samsung

[jjanssen7]

Re: Backlight rare white rings. Samsung 50in 4K TV

I've seen 4 or5 like this mostly LG models.

[chrismurphy]

Re: Backlight rare white rings. Samsung 50in 4K TV

Faulty LED diffuses , its as simple as that
replace the strips