LCD diffusers

[tom66]

I got an LCD TV for free today . A 42" Bush Full HD with Freeview set... Powers on and gives a picture.

Problem is with screen, lots of mura on it, more like backlight unevenness. Can't fix it by just laying it down unfortunately.

Completely tore it down to find two of the backlight layers have clear patches in them (where the fault is on the screen) so clearly they aren't going to work.

I'm looking for diffusers for a 42" LCD. If anyone has a broken screen 42" LCD, please let me know as I may be able to get those diffusers to work in this TV.

I am thinking of re-doing the diffuser, maybe with some kind of spray paint.

[multimeter]

Re: LCD diffusers

have you tried large sheets of tracing paper?

[tom66]

Re: LCD diffusers

have you tried large sheets of tracing paper?

I'm not sure how well it will work, but I'll consider it. I've found a supplier in China of these diffuser sheets, so I may be able to buy replacements.

[multimeter]

Re: LCD diffusers

i think you can get the standard tracing paper which has a slightly matt finish to it,and you can get a waxy type which might distribute the light better,ive never tried it, may work,both are translucent

[cadiman]

Re: LCD diffusers

These do need to take a bit of heat.

The ones I have taken apart looked very workable as far as taking from other panels and cutting to size.

You need like 4 sheets and I wonder if they are polarized or set in a specific order.

I always keep them in order and they may also have side A and B respectively, but not sure.

I have worked with them on the 7" tablet panels and those are in a specific order and are different from one side to the other.

[tom66]

Re: LCD diffusers

Okay so I took out the diffusers. Cleaned them and laid them out to dry for a day.

Put them back in... and it works . No mura .

Damn! It is a difficult job. I spent an hour trying to get the LCD panel together and was so worried about damaging the panel which is so very, very fragile.

Unfortunately I did scratch it with the speakers but the scratches aren't very visible.

42" Full HD Freeview set.

Not bad for free .

[cashkennedy]

Re: LCD diffusers

So was the white part all removed after you cleaned the filters? or did the clear part return to being white??? Did you have to adjust the brightness after the cleaning?

Your picture looks even, but the colors look a little off, might be from the filter not making all the light uniform white.

[tom66]

Re: LCD diffusers

So was the white part all removed after you cleaned the filters? or did the clear part return to being white??? Did you have to adjust the brightness after the cleaning?

I did a few things. I cleaned them so that the marks were only faintly visible. I put them in some sunlight and let them dry, which may have caused some of the sheet to clear up. (I'm not sure...) Then I swapped around the filters so that the bad filter was behind a good one. I cleaned the back of the LCD panel too. All of this made the picture look much better, to the point where it looks as good as most other LCDs, including my 42" LG (which has an LG Philips panel, not some CMO crap.) Strangely, the only remaining problem is the general backlight unevenness all LCDs exhibit - it's not related to the mura there, it is more like random clouds, like on my LG 42". (Sort of visible on dark scenes.)

This LCD is pretty poor, it struggles with black and white. White appears a little cyan-y on the edges, and it has difficulty distinguishing between zero percent black to around 10 percent black - they look the same.

SYour picture looks even, but the colors look a little off, might be from the filter not making all the light uniform white.

I found it was set to Cinema mode, and set that back, the picture is pretty good now. The flash on the camera probably doesn't help.

[budm]

Re: LCD diffusers

How about the Polarizer sheets, did you have to cleam them also?

[tom66]

Re: LCD diffusers

How about the Polarizer sheets, did you have to cleam them also?

I cleaned that too, there was only one thick plastic polariser. It didn't have any marks on it, but I cleaned it because I got fingerprints on it. One thing that is so very difficult with these things is that you can touch something and get marks on it and you'll only notice when you put it all back together. However, I checked at every point to avoid this... would advise anyone trying the same to do this.

[budm]

Re: LCD diffusers

Sounds like you have done very good job!

[tom66]

Re: LCD diffusers

Sounds like you have done very good job!

Thanks!

This LCD will be going to a relative as they want a nice big LCD TV. The Samsung 40" went to a friend. I have sold lots of TVs to friends, more than selling to other people! The price is probably half that of a new TV, maybe that is why...

Nice to save something from the dump (as this thing was literally on the curb, waiting to be picked up), and this adds to my experiences in LCD repair. I guess it is possible to cure both types of mura - backlight and LCD, as I've had two TVs with mura problems and have been able to successfully fix both.

I asked the owner of the TV if he wanted anything for it but he said keep the money, and gave me the remote and power cord too. He had bought a new TV to replace this one.

[budm]

Re: LCD diffusers

Do they have electronics recycler in your area, like WWW.CRC.ORG where I do my volunteer works?

[tom66]

Re: LCD diffusers

Do they have electronics recycler in your area, like WWW.CRC.ORG where I do my volunteer works?

We do have a dump that sells electronics - but they don't often sell TVs and you can only buy one piece of electronics every 3 months.

There are a few computer companies around here. I have considered collecting together all my old hardware and donating it. I have about three Pentium III machines somewhere...

[cashkennedy]

Re: LCD diffusers

We have http://www.cacrc.com/ here in baton rouge. Their name is very close to budm's place but theyre much less "skilled" / or enviromental in my opinion.

First of all the refuse to take tv's (maybe i should call them and give them some flyers saying if anyone brings in a LCD tv to bring it to me). Second they now charge for really old computers (like 7 dollars per CRT...., while the dump only charges me 15 dollars for every ton (i bring crts to the dump a lot))

They also dont do any component level repair on anything, and infact theyll barely touch a computer that is broken.

(ill add more later, be back later)

[cashkennedy]

Re: LCD diffusers

They used to collect dell and other standard computers and then donate them to schools. But schools are now really picky and wont accept free computers, cause core 2 duos arent good enough for people who are on food stamps and welfare and come from the ghetto. They also want warranties on everything.

So now they just have a govt supported program where poor people can buy used modern core 2 duo dells with windows 7 and a lcd monitor for like 60 dollars... but no "poor" people want desktops they want ipads, so the program does nothing.

The place sells anything "good" they get on ebay, and scrap processors for gold. The rest is recycled as electronic waste or something.

Im pretty sure the whole program is just another government waste to give people jobs, and does nothing really affective.

[tom66]

Re: LCD diffusers

You can blame excessive consumerism. We must all have the latest and greatest: fashion, electronics, cars, etc... Nothing is ever "good enough" if it's a few years old. I know someone who has just got the latest iPad 3 (after having 1 and 2) and I asked him to list all the great features about it and he couldn't! Didn't know anything about it - just knew it was shiny and new!

[Jasgriff]

Re: LCD diffusers

Don't get me started on apple fan boys.....

[severach]

Re: LCD diffusers

DO get me started on apple fan boys!

Youtube: iPhone4 vs HTC Evo

[RJARRRPCGP]

Re: LCD diffusers

"iBUSH" ? Parody of Bush? LOL.