Panasonic TX-L37V10B possible mura or shadow or dark areas

[statalite]

I had mura on a 42" Toshiba LCD.

The fix was to remove the screws and back cover, leave the TV laying down for two days, then replace the cover, tighten the screws slightly (but not all the way, just enough to hold the case together.) Then enjoy.

The TV previously had really bad mura in the middle of the screen. There's a tiny bit left, but it's 95% gone and far better than when I got it.

I think that it is caused by excessive pressure on the LCD. It is accelerated by thermal effects. It is due to unevenness of the liquid crystal in the panel.

Hi I took toms quote from another thread. https://www.badcaps.net/forum/showthread.php?t=15576 so I am kind of addressing tom66.

I think my newly aquired second user TV (Panasonic TX-L37V10B) has mura, possibly.
For a few centemeters on the left and right of the screen it is darker looks dirty but isnt, classic shadow, like a vertical strip it goes from top to bottom on both sides. More visible in light scenes and all inputs. Does this sound like mura?

I only noticed this the day after collecting the TV, and not being aware of this type of thing existed I paid and left with the TV.

I have yet to identify how to fix the tv, if at all possible. I am trying to avoid opening the back up.

I have tried pressing a cold item from the freezer as a video on youtube suggested but to no avail.

I am now trying the technique you are describing tom66. I have removed the base and laid the screen down on the carpet. I have laid it face down, so the screw side is on top, is this what you did tom66?
I have lossened the screws, and it is laying screen down. What is the purpose of removing the cover only to put it back on after 2 days, what effect will this have?

This may not come to anything, but worth a try. Any advice appreciated.

Kind Regards,
Statalite

[Alastair E]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Loosening the screws of the case will remove any stresses the case may be presenting to the screen-frame.

Must admit--Ive not heard of this cure for Mura--I'll try it when I find another set showing it.....

Ive seen quite a few Toshiba with this issue--One set was perfectly fine when cold, but after 6 hours showed up pretty badly. Cold the next day--perfectly fine again

[tom66]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

I did use this method to fix the issue, but it came back a month later gradually. I gave it to a friend for a very low price because I couldn't sort it. Crappy Chimei panel!!

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Hi thanks for the replies.

I thought I would post a picture so you guys can see what its like.
I put it on this radio channel for the white background.
It looks like the picture from cold.
I wonder if this picture can give any insight as to what it is and what I could try to fix if possible.

Would laying it down flat on its face make it worse?
Should it be lying on its back with the screws down, or will this be worse as possible dust can get in?

[tom66]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

That is not mura, that is backlight unevenness.

It is possibly due to slightly worn out bulbs from the panel being old. Probably bulbs getting older and darkening on the ends. I am guessing this TV either uses an LG panel or a Panasonic IPS Alpha panel.

It might be annoying but 99% of LCD panels have this. Pretty much the only panels I have seen without it are the smaller ones, and LCD monitors. Look up LCD uniformity issues.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

That is not mura, that is backlight unevenness.

It is possibly due to slightly worn out bulbs from the panel being old. Probably bulbs getting older and darkening on the ends. I am guessing this TV either uses an LG panel or a Panasonic IPS Alpha panel.

It might be annoying but 99% of LCD panels have this. Pretty much the only panels I have seen without it are the smaller ones, and LCD monitors. Look up LCD uniformity issues.

Ah right backlight unevenness, thanks for the clarification.
I have looked up on the net for a fix, but the only one I found was from you in this thread: https://www.badcaps.net/forum/showthread.php?t=20070
Is an easy fix posible or very hard to say or no possible fix?

[tom66]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Not possible to fix - fundamental characteristic of how the panel is made.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

ok thank you.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

I just picked the tv up from the carpet and it sounds like their is a screw loose inside the tv, is this something I need to open the case for essencial?

[tom66]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Rare for screws to go loose but sometimes plastic clips etc. can break off and make a noise inside the TV. Not usually essential unless it bugs you.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

It was bugging me and looks like it was a loose plastic clip. in trying to find the cause i shook the tv a few times, i was about the but the back on again and I saw a small silver circular ring with teeth on it, im sure this has come out of the tv, you guys might not know what it is? but I cannot see where it goes, so looks like im putting the back on again and hoping.

[bammbammfran]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

it is probably YELLOWING of plastics
see
http://youtu.be/vI1tuQ_3FG0

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

it is probably YELLOWING of plastics
see
http://youtu.be/vI1tuQ_3FG0

Possibly but what hes doing on there is something way beyond what I would be able to do. Around 10 minutes into the video he does decribe what I am getting, but he said it would be a chemical process. thanks anyway.
Looks like il just have to live with it providing it comes back ok when I screw he back on again.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

At the moment im worried about this cog ring thing i found.

[bammbammfran]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

At the moment im worried about this cog ring thing i found.

sounds like a lock washer that would help retain a screw
probably a grounding screw
should be ok without it

[bammbammfran]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

de-yellowing plastics
one site

http://www.exisle.net/mb/index.php?/...ent-after-all/

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Possibly a lock washer for a grounding screw, however I have put the TV back together as it was working as before.
Thanks for the link on de-yellowing plastics, this and the youtube video make it seem highly technical for me to take it apart and deal with something which I prob mess up.
You seem very knowlegable about this so thanks for helping me.

[statalite]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

it is probably YELLOWING of plastics
see
http://youtu.be/vI1tuQ_3FG0

After watching your video again, I am getting curious and am contemplating if to try this or not, can you tell me if possible if the IPS-Alpha panel inside the TX-L37V10B would be made of the same style components as the monitor in the video? I am just a bit nervous about taking it apart and seeing something completly different inside. I cannot seem to find any references for this part online.

Kind Regards

[bammbammfran]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

Can you post a picture of the complete back of the unit showing the boards and wires ?

[tom66]

Re: Panasonic TX-L37V10B possible mura or shadow or dark areas

It's a LOT of work to take apart a large LCD like this (anything around 40" or bigger is "large" in my mind.)

You're dealing with a piece of LCD glass about 1.5mm thick and 37" diagonal. It is attached to the electronics via delicate bonded tab drivers. If you crack the panel or break a bond, game over. You need a couple hours free ideally, because you want to work nice and slow. No awards given for doing it fast and screwing it up.

I wouldn't recommend it unless you've done it before or can afford to break a panel accidentally. I still hate doing them even after doing it about 5 times. On my third panel I was assembling I was 1mm off on the glass alignment and plastic. I pushed down on the metal frame and cracked the panel. Ruined a nice 40" Sony panel right there. It's something I would NOT recommend a newbie try.