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

[jeffer76]

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 ?

I tried flipping the sheet over. Bottom side is slightly different. No change.
No plastic spacers.

[jjanssen7]

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

Still curious about this... I have a Samsung UN55F8000 (that has never been apart) that has the same issue. I'm wondering if anyone knows if the diffuser sheets can get old or distorted and not transfer light the way they originally did? In my case it's possibly due to age, in the case of this thread it is possibly from bending?

Other long-shot... jeffer76, Did your diffuser spend any time in direct sunlight while the TV was disassembled? I'm wondering if the TV I have (I have no history on it) spend time in the direct sunlight which changed the property of the diffuser sheet.

[saddle_au]

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

Bow in the sheet or incorrectly positioned sheet. Last time I saw something like this, it turned out there is a slight angle of entry for the leds into the edge of the sheet. The light doesn't seem to bounce it's way through the sheet like it should. The sheet was slightly off centre and it was pressing hard on the leds.

If you can place the sheets flat on a desk, shine a led torch into the edge and see if you still get the same darker area in the middle. You'll have to do this with the lights turned down because a led torch isn't as strong (normally). I use one of those powerful cree torches for this job when I'm trying to clear water marks (yes you can clean these out). Worst thing to do is to crease the sheet when moving them around, the sheet becomes a throwaway. I keep sheets and leds from busted screens as replacements, takes a while to get them out neatly. Doesn't take much room to stack lots (like those poster racks at a cinema with supporting cardboard between them).

[Pooshoes]

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

I tried flipping the sheet over. Bottom side is slightly different. No change.
No plastic spacers.

I have the same issue with a kdl-70w840 tv but it had a BL error blink code so i bypassed it and had bright edges like you. I replaced lights with new strips and no improvement. I replaced the LED driver board with no improvement. Unplugged Tcon and no improvement in LED output. So power supply or mainboard error is the culprit. Did you happen to solve your problem? @jeffer76

[Pooshoes]

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

Replaced power supply and mainboard and the same issue persists. Maybe i replaced the led driver board with another faulty one?

[Davi.p]

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

What the hell of a repair technique is this?? Changing boards brainless without even check if the leds are evenly lighted up? Disaster...

[nomoresonys]

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

Looks like a lot was tried, thinking it must be how the sheets are going back in, everything needs proper spacing, if there was standoffs, they need to be put back.