samsung un40es6100 flickering backlight

[freakaftr8]

so reading the other posts I thought maybe it was similar to this problem but not really. all LEDs work already pulled the panel but the back light is flickering I tried re soldering the power supply and all components on it but didn't help I tried flexing the panel and it seems that if the back lights flicker no matter what sometimes it'll come on at all and sometimes they stay on for a sec in the next liquor out then I'll come back but them and then they fade out. There are three wires going to each LED strip there's only two strips one on each side they both act the same neither or shorted and all LEDs are lIt do you think it might be related to the white goo issue people have been talking about?

I should note that even when the LEDs go out the screen is still working so it's simply a backlight issue only these LED backlight strips have 3 wires.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

oddly though LED strip 1 has two blue wires and one White wire the other LED strip has 2 black wires and one white wire. What I've noticed is the two blue wires when the LED strips are not operating at the time I have about 117 volts DC when operating go down to about 85 volts. the other side black wires are not getting any voltage at all but when the LEDs power up comes up to about 24 to 34 DC. The two middle white wires consistently get 48 volt DC. these wires go directly to the output pin of the LED controller itself and I'm wondering if the Led controller could be bad but I've never seen one that flickers like this.

when I first picked up this TV as pretty confident that I would find a shorted led but surprisingly it doesn't look at this way. I don't see anything on the power supply shorted.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

Also this model will keep the backlight on indefinitely if mainboard is disconnected from the power supply. Every.once in a while I'll get a backlight flash. Also I can unplug tv and reconnect and get backlight for.up.to 7 seconds then either starts dimming or goes out altogether.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

Here's the led strips

http://i845.photobucket.com/albums/a...psuebdvfpb.jpg

http://i845.photobucket.com/albums/a...psjrvwscgo.jpg

[tom66]

Re: samsung un40es6100 flickering backlight

In the user menu, is there an option for dynamic backlight, maybe try turning that off?

[freakaftr8]

Re: samsung un40es6100 flickering backlight

actually what I was trying to say is the back lights do not work is it there's an issue with them they're technically out completely. Although I can see the screen working with a flashlight. What I meant to say was this model TV is designed to light up the back lights when the main board is disconnected from the power supply I can tell because every once in awhile I get a flicker out of the back light When I try it this way but generally there's a problem I'm assuming with the power supply because all the LEDs are working on each of the two strips

[freakaftr8]

Re: samsung un40es6100 flickering backlight

has anybody ever seen an intermittent LED driver output IC?

[tom66]

Re: samsung un40es6100 flickering backlight

I've encountered intermittent chips of all sorts, if that counts.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

Ok. Well I'm still trying to access this issue. I'm going to try reflowing all smd components that runs off the IC first

[freakaftr8]

Re: samsung un40es6100 flickering backlight

Just thought I'd note just got done replacing the backlight driver IC on the power supply and all is well. Symptoms were flickering backlight on and off acting like a bad connection but it was not. No shorted LEDs on any of the strips. Just an intermittent backlight driver IC.

kind of thought there is something up here as I was getting some really off the wall readings from the IC.

[tom66]

Re: samsung un40es6100 flickering backlight

Glad to hear you fixed it. Sounds like these LED TVs are going to be a real pain to debug.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

Probably. The negative side of the backlights on this model pull directly from the IC. Like a ground. Ic part number SLC2012M

[tom66]

Re: samsung un40es6100 flickering backlight

Current regulation, the IC will balance the current between each strip. Problem is, it means lots of power dissipation if LEDs go short circuit.

[freakaftr8]

Re: samsung un40es6100 flickering backlight

hence why others have the power supply going to shut down possibly? When an LED shorts? Like overcurrent shutdown?

[tom66]

Re: samsung un40es6100 flickering backlight

I imagine the IC itself will go into thermal shutdown.

[budman67]

Re: samsung un40es6100 flickering backlight

I can understand about a driver IC shorting but an LED shorting??? Is that even possible??? You cant test an LED with a DMM as there is no circuit.

[ReeceyBurger123]

Re: samsung un40es6100 flickering backlight

I can understand about a driver IC shorting but an LED shorting??? Is that even possible??? You cant test an LED with a DMM as there is no circuit.

Watch this Bud:

https://www.badcaps.net/forum/showthread.php?t=52928

[fredaelsadany]

Re: samsung un40es6100 flickering backlight

HALLO
I meet this fault and all back is ok . I measured PFC voltage it is under 360v (340v) I change all resistors (smd) in the divider of pfc (390v) and tv is ok .
one off these resistors is changed in value (become smaller !!!) and pfc become 385v again and tv work normal . try measure PFC .
THANKS

[Electronic Handyman]

Re: samsung un40es6100 flickering backlight

It seems that the new Led designed sets have lots of probs involving leds and especially led failers. I recommend that anybody that owns a led set to go into the picture settings and turn the backlight controls down as much as they can tolerate.That should help to prolong the leds life span and its circuitry.

[Zaman Kay]

Re: samsung un40es6100 flickering backlight

HALLO
I meet this fault and all back is ok . I measured PFC voltage it is under 360v (340v) I change all resistors (smd) in the divider of pfc (390v) and tv is ok .
one off these resistors is changed in value (become smaller !!!) and pfc become 385v again and tv work normal . try measure PFC .
THANKS

Hi. Is this that u change?