Samsung sound no picture

[JAnoY]

I'm having an issue with my Samsung UN46D6300SF. The backlight will go out periodically. I still have sound and if I shine a bright flashlight on the screen, I still have a picture but no backlight. The problem comes and goes. I've checked all the capacitor caps for bulges and they all look good. Even got a magnifying glass to get a better look at the bottom of them (had one blow out the bottom on a computer monitor before).
I know with the CCFL backlit sets, that if 1 lamp goes, the psb cuts power to them all. Do the LED backlit sets do the same thing?

[Shinju]

Re: Samsung sound no picture

When you unplug the mainboard from the power supply and plug in the panel does the LED lights illuminate and stay lit?

[JAnoY]

Re: Samsung sound no picture

I'll have to wait until the backlight goes out again. Everything is up and running now. Only cuts out sporadically. Could go a couple days without an issue. Could go a few minutes. That's what is so frustrating. Was just wondering if anyone else had a issue like mine and knew what was causing it.

[JAnoY]

Re: Samsung sound no picture

IF it was out all the time, be easier to track down. But even when it goes out, there's no specific time frame it is out for. Could be a few seconds, could be hours.

[selldoor]

Re: Samsung sound no picture

Sounds like it is heat related - bad solder joint perhaps.
Please could you update your profile with Country and Mains voltage

[budm]

Re: Samsung sound no picture

If one of the LED string goes open circuit, the protection circuit will kick in and stop the LED driver circuit. It will hard to troubleshot since it is very intermittent like that.
You can check the BL_ON pin to see if it goes away when the backlights are off to give us a clue on what happens.

[JAnoY]

Re: Samsung sound no picture

Ok, So the backlight finally go out again after working for several days. I took the screen out to see the backlights. It looks as though there is only 1 string of leds along the top of the frame with a plug at each end. I turned on the tv and got sound so I knew the set should be on and working, but part of the led string dimly blinked. About 1/3 of the string on the left side did nothing. I tried to unplug the left plug and the set did nothing. Power light blinked but the set wouldn't power up. Tried the right side plug, same thing. I had both sides plugged up, and still 2/3 of the leds dimly blinked. I tried to see which led was the last in the string that wasn't working at all, but they all poped on and I get blinded by the entire string shining brightly. Never had time to check voltages when the string was out, see exactly how many of the leds were not blinking, ...nothing. It's up and working fine. Thinking about just replacing the led string and keeping my fingers crossed. But where the heck do you buy them?

[mmartell]

Re: Samsung sound no picture

Ya good luck with that. Shopjimmy was starting to harvest them due to their failure rates but still very hit and miss.

Use a meter in diode mode across each led and see if any are problematic.