Samsung QN55Q70AAFXZA Half Screen Dim

[Davi.p]

I think you reported bad the power b. pins measurements, my guess is that the L is the leds line, but the H is the light sensors to the side of leds, this last is the problem, thus why the light feedback is wrong on one side? my guess is that the assembly job of the leds strips and fresnel sheets positioning puzzles the light feedback..

ps: normally edge led strips broken in two parts are specular thus not same part

[lotas]

L - LOW
H - HIGH
Most likely one LED has two LEDs (one for low light (playing the role of darkening), the second for high light.

[Davi.p]

I don't think, i see the photo, only 4 pins per strip, 2 for leds, 2 for sensors

[Diah]

L - LOW
H - HIGH
Most likely one LED has two LEDs (one for low light (playing the role of darkening), the second for high light.

+10000

[lotas]

The correct 4 contacts are H+ and H- (this is the power supply for the bright ones) and L+ and L- this is the power supply for the dim LEDs.

[Tom C]

Yes, you are correct. H is for the white light, L is for the blue.
Original set are the same part number for each side. Of the original pair, one side lights only the blue, other both white and blue. The blue only strip was defective.
I usually buy tv parts from Shop Jimmy, but they didn't stock the edge strips I needed.

[Diah]

can you upload high quality photo of the PSU from the top and down side ?

[EazyBone]

Yea now you know, always plug in TV before setting it back up to test the strips. Always disc main board from PSU before doing so, on Samsung anyway.

IF you remove the only blue strip and plug it into the other connector... And plug in see if it lights up only blue still with other connector. Maybe? I may try just to see

[Davi.p]

OK,, strange design, i don't know why blue leds, maybe they lit or not depends on the user settings..

[EazyBone]

Blue LEDs are used for QLED tvs. They use blue LEDs and a yellow diffuser

[Tom C]

The white/blue are in pairs (clear/yellow) as seen in the photo. I now know from, thanks to this forum, to power up the LEDs before reassembly.
Unfortunately, while moving the LCD panel, I cracked the corner. Pretty sure that's the end for this TV.

I want to thank all who helped me with this project and am looking forward to being part of future discussions.

Tom

[EazyBone]

Rip tv. Hey you learned something. I cracked the first 3 tvs I got and since then never again. Gotta learn somehow

[nomoresonys]

Well at least it was only a samsung, might be the best that could happen...Lord only knows how much trouble that tv could have caused you.

[Tom C]

Yeah, but I still enjoyed the challenge, learned something and found this forum. Win all around.