UN65F6300 LED's failing

[pyr0ball]

I'm having an almost identical issue to the one posted here

My symptoms:
Dim lower part of the screen. Top part will flicker at regular intervals when brightness is higher.

I've already purchased a replacement SMPS module after poking around on the power supply and concluding (incorrectly) that the square wave on voltage I was seeing was from the supply.

I'm very handy with a soldering iron but didn't want to disassemble the TV entirely unless I could find some replacement LED's to swap first. Searching the forum hasn't really turned anything up and I can only really google the full LED strip modules which either come in single sets or overpriced kits (looking at $150+ minimum for the wrong size modules I would need to swap led's from).

Is there a way I can isolate which specific LED's are faulting?

I've got access to an oscilloscope, DMM, and lots of other equipment if someone would be able to give me a rough guide on what to look for.

Panel module: CY-HF650CSAV1
suspected LED strip modules: 2013SVS65F L11 & 2013SVS65F R9

[CapLeaker]

Re: UN65F6300 LED's failing

You do that 2 ways. With your DMM in diode mode, or a CV CC regulated PSU. LEDs work on CC (constant current). You can measure the voltage on each string and we can tell on what string that bad LED is.

HIgh resolution, straight shot pictures of your screen fault and the boards would be nice too.

[pyr0ball]

Re: UN65F6300 LED's failing

Pics:

Top of the power board


Bottom of the board


LED connector top w/ pinout silkscreen


LED connector bottom with silkscreen (and my testing wires)


Power output silkscreen


Test image 1


Test image 2


Test image 3

[pyr0ball]

Re: UN65F6300 LED's failing

You do that 2 ways. With your DMM in diode mode, or a CV CC regulated PSU. LEDs work on CC (constant current). You can measure the voltage on each string and we can tell on what string that bad LED is.

HIgh resolution, straight shot pictures of your screen fault and the boards would be nice too.

Had a chance to review those pics?

[CapLeaker]

Re: UN65F6300 LED's failing

what happens if you set the backlights low as they can go? Does the flicker stop?
What are the voltages on the led connector? Measure from 1- to 1+, all 4 strings

[pyr0ball]

Re: UN65F6300 LED's failing

what happens if you set the backlights low as they can go? Does the flicker stop?
What are the voltages on the led connector? Measure from 1- to 1+, all 4 strings

Flicker does stop on lower brightness.

I'll have to test again to measure across the poles. I was testing from + to ground before.

[freakaftr8]

Re: UN65F6300 LED's failing

That is for sure a bad LED or 2 in the strips. These power supplies load on 3 or 4 strips at a time. Noticed your nearby. I repaired at 75 inch version. Not a walk in the park I might add.