Samsung un65eh6000 backlight issue

[bstewara]

Hi All,
I have a Samsung Un65eh6000 with a backlight issue.

The original issue was backlight current was present but led strips did not light

I tested the backlights and all tested to be working properly.

I assumed then that the power supply was not sending current to the led strips.
Power supply board part number BN44-00560A.
After checking voltages it appears that current output at connector CNL802 was outputting the correct current 189 VDC on pins 1,2,6, and 8.

The issue then was there was no ground on the connector 4,8,11, and 12.
I then created a case ground on pins 4,8,11, and 12 and all backlights came on.

My issue now is they're at approx. 30% and will not ramp up to normal range?
Would anyone have any suggestion to what is limiting the backlights to ramp up to normal operating parameters?


Thanks in advance

[nomoresonys]

Re: Samsung un65eh6000 backlight issue

so are you trying to turn them up in the menu?

[lotas]

Re: Samsung un65eh6000 backlight issue

You have a strange solution to the problem - short-circuit 4,8,11, and 12 to the ground of the TV.

[nomoresonys]

Re: Samsung un65eh6000 backlight issue

lol, I didnt get that part.

[bstewara]

Re: Samsung un65eh6000 backlight issue

No
I’m just trying to figure out a solution.
Try to understand why the backlight come on when grounded to the chassis.

Backlights have been tested 2x. Just not sure what controls the backlight circuit.

[R_J]

Re: Samsung un65eh6000 backlight issue

How are you testing the backlights? The problem is very likely one bad led in the circuit causing the protection to shutdown the backlight circuit.

[bstewara]

Re: Samsung un65eh6000 backlight issue

Hi,
Using a TKMDR Backlight tester.
Tested each bead then each strip 63vdc each strip. 3 strips per circuit 189vdc per circuit.
They all come on but can’t seem to get the system to ramp up?

[R_J]

Re: Samsung un65eh6000 backlight issue

The tester outputs a max 30ma, under normal operation the led's usually draw over 150ma,
led's often fail under higher current.
the only way to test the led's with the tester is to check each one individually and even then that might not work.

[bstewara]

Re: Samsung un65eh6000 backlight issue

Thank You RJ
I may just try another set of strips.

Regards

[R_J]

Re: Samsung un65eh6000 backlight issue

If you are going to open the panel, you can operate the back lights without the panel installed, so make sure the backlights are all working before reinstalling the lcd panel, this will reduce the chance of breakage.

[alfatv]

Re: Samsung un65eh6000 backlight issue

Hi All,
was outputting the correct current 189 VDC on pins 1,2,6, and 8.

This is voltage, not current.

By grounding other sides of the strips, there is no current limiting in place, you can damage the strips by doing this. However they might on last legs anyways based on your description.