Kdl-70w830b sim in middle of picture after backlight repair

[jeffer76]

I am working on a Sony Kdl-70w830b that had bad led backlights. TV was shutting down with the standby light blinking red four times. I replaced the bad LED strips. (Whole metal frame)
Now I am getting a picture that is bright on the right and left side but dim in the middle. I am curious if anybody else has experienced the symptom after working on an edge lit led tv?
I can only assume that the plastic sheet that is supposed to glow from the LEDs has a problem. I'm wondering if it's because when I removed the thick plastic sheet it bowed in the middle Causing the light to not flow through it properly. Do you think that is possible?

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Anyone experienced this problem before on an led edge lit led tv?
It's as if the light is not traveling through the plastic sheet.
Let me know please.

[dkneyle]

Re: Kdl-70w830b sim in middle of picture after backlight repair

I reckon you are probably on the money about having a sheet that is bowed. Logically it is about the only thing it could be. Having done this type of job a few times it would be very easy to have a bow occur. I know it's a pain, but strip it down and try again!

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

I have tried everything I can think of. Adjusting the strips closer. Pressing it flat. The light just won't travel through the plastic. I'm guessing there are cells inside the plastic that the light travels through and when removing the plastic sheet the bow fractured those cells. Not sure.

[dkneyle]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Mmmm. Have you done some internet research on how edge-lit LED panels work to confirm if such cells do exist? I've got nothing else of offer. Hopefully someone with more knowledge than me has an answer for you.

[budwich]

Re: Kdl-70w830b sim in middle of picture after backlight repair

what exactly is being shown with the second picture in your initial post? is that the before, after, or otherwise? are the edge leds only on the sides or all the way around?
Likely all the way around... if so, the next question is what type of leds did you replace with? EXACTLY the same? Maybe there is an issue with output / dimming of the top and bottom versus sides?

[jjanssen7]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Even in edge lit TVs, there are still usually multiple sheets... any chance you mixed up the order?

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

what exactly is being shown with the second picture in your initial post? is that the before, after, or otherwise? are the edge leds only on the sides or all the way around?
Likely all the way around... if so, the next question is what type of leds did you replace with? EXACTLY the same? Maybe there is an issue with output / dimming of the top and bottom versus sides?

Second picture is one of the test photos built into the tv. Harder to see the bright edges in this photo. This is an after photo. The edge leds are only on the two sides of the set. The leds are exactly the same part number but do have a slight variation in color.

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Even in edge lit TVs, there are still usually multiple sheets... any chance you mixed up the order?

No. I am very careful about taking the tv apart in a special order so as to prevent that from happening. Also I believe the image on the screen would not look correct if they were in the wrong order.
I was thinking that maybe as a result of pulling back the final white paper sheet, the one taped to the frame, somehow changed the way the light is reflected. You have to pull back that one to gain access to the led strips. I didn't remove it completely. Just pulled it back far enough to gain access to the light bar assembly and replaced the whole assembly.

[neilc6]

Re: Kdl-70w830b sim in middle of picture after backlight repair

From optics, light travels though tbe sheet using total internal reflection. Same as light travelling through a fibre optic cable. Looks like bowing the sheet damaged it enough for the light to not pass through like kinking a fibre optic cable.

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

That is what I was thinking. It's the only logical conclusion I can come up with. Do you think that it could be a brightness problem? Not enough light to pass all the way through the sheet? I hate to just give up on this.
Thanks for all the reply's. All opinions are appreciated

[budwich]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Second picture is one of the test photos built into the tv. Harder to see the bright edges in this photo. This is an after photo. The edge leds are only on the two sides of the set. The leds are exactly the same part number but do have a slight variation in color.

ok.... but there is something "funny" with the second picture.... why is there brightness across the bottom at different places. This brightness doesn't appear to "agree" with your other pictures.

[R_J]

Re: Kdl-70w830b sim in middle of picture after backlight repair

You say: "I replaced the bad LED strips. (Whole metal frame)" was this from the same model panel? It looks like there is quite a gap between the led's and the diffuser sheet

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

You say: "I replaced the bad LED strips. (Whole metal frame)" was this from the same model panel? It looks like there is quite a gap between the led's and the diffuser sheet

So I thought the same thing. The metal plate that the led strips are attached to can be adjusted so I slid it closer to the diffuser sheet. The leds were practically touching the edge of the sheet. No change.

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

ok.... but there is something "funny" with the second picture.... why is there brightness across the bottom at different places. This brightness doesn't appear to "agree" with your other pictures.

That brightness that you are seeing is a reflection from our over head lights.

[budm]

Re: Kdl-70w830b sim in middle of picture after backlight repair

So are the LED assemblies exactly the same as the original one and matched the LCD panel model number? I did not see the answer that was asked in post #13.
What is the LCD panel model number?
What are the P/N of the old LED assemblies?
What are the P/N of the replacement LED assemblies?

[diif]

Re: Kdl-70w830b sim in middle of picture after backlight repair

I was thinking that maybe as a result of pulling back the final white paper sheet, the one taped to the frame, somehow changed the way the light is reflected. You have to pull back that one to gain access to the led strips. I didn't remove it completely. Just pulled it back far enough to gain access to the light bar assembly and replaced the whole assembly.

Was it put back as smooth as it was taken off ?

[mmartell]

Re: Kdl-70w830b sim in middle of picture after backlight repair

If it has the same properties on both sides of the sheet take it out and flip it over. If you bowed it in one direction flipping it over might help to restore its properties.

Are there any plastic spacers beneath the sheet to keep that layer from sagging ?

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

So are the LED assemblies exactly the same as the original one and matched the LCD panel model number? I did not see the answer that was asked in post #13.
What is the LCD panel model number?
What are the P/N of the old LED assemblies?
What are the P/N of the replacement LED assemblies?

The led assembly came out of a kdl-70w850b model. They appeared to be the exact same part. Shape, size, numbers. I have since put the tv back together and given up on it. This tv was a monster to take apart and put back together and I don't want to open it again.

[jeffer76]

Re: Kdl-70w830b sim in middle of picture after backlight repair

Was it put back as smooth as it was taken off ?

For the most part yes. The white sheet that's taped to the frame got a few wrinkle marks from pulling it back. They used very sticky tape on this model.