Lg 65UB950V No Image

[Megaule]

Hello, i have this Tv that stops working. When i turn on the LG logo in the front will light up and fade out. I hear the relays clicking and they works, because i replaced them!! I have the 3,5v standyby, when i power on the tv i have also the 12v and 24v! Only the "82,2v" for backlight is missing. On the mainboard the Led ld2300 is on. The led ld1900 (its for tcon =on i think) will shortly light up then go out. I have no Drvon and also the 12v for tcon supply is missing. After ca 15 seconds the led on the power supply board will flash 5 times then pause then 5x....and so on... Errorcode??
Audio i do not hear. Also witha flashlight on screen i will see nothing....

Can someone help me please?

[Megaule]

Re: Lg 65UB950V No Image

The pwr supply board is lpg5565-14ul12
Or eay63149101

[nomoresonys]

Re: Lg 65UB950V No Image

Good straight on pictures of each board and one of the whole back as to see how everything is connected, and a clear picture of the map/legend of the expected voltages on the powerboard, should be close to connector marked P801 or similar.

[Megaule]

Re: Lg 65UB950V No Image

Hello here are the fotos, the relays are working... Even if it don't look so🙈😬

[An-klamm]

Re: Lg 65UB950V No Image

I had a 65LA on me the other day with similar issues.
After you have removed the thermal pads, you can use a hair dryer to heat the CPU on the motherboard a little (10-30 seconds was enough for me) and then try to start the TV.
It worked for me.
I then reflowed the CPU and the TV ran until the "customer" picked it up and put it in his car.
Screen breaked....

[Megaule]

Re: Lg 65UB950V No Image

Hi An klamm, thanks for your answer, what for an ic is the cpu?

[An-klamm]

Re: Lg 65UB950V No Image

Just heat the yellow marked area for about 30 seconds (after you take off the soft pads) and then you can test it.
If that works, then you can let it cool down completely and try only one IC etc. Then you can narrow it down.
On mine it was on the red marked one as far as I know. But it is already 2 weeks ago.

[Megaule]

Re: Lg 65UB950V No Image

So i heated up this area, but nothing... Same problem. But i tried to heat the chip on the tcon and i noticed that after heating the tconchip the led on mainboard that lights up when tcon is on (i think) will light for about 2-3 seconds. When the tconchip is "cold" it will be light up only for a moment about 0,5sec when i try to turn on the tv

[Megaule]

Re: Lg 65UB950V No Image

Now i conected the tcon 12 v supply direct to the psb, and the light zhat shows tcon = on on the mainbord will go on and remain on. But the "errorled" on psb flashes 5 times like before... So same error!!??

[Megaule]

Re: Lg 65UB950V No Image

Always with 12v directly conected to tcon i pull up the drvon signal to 3,5v with 1k resistor. Same problem only that the errorled flashes 7 times now....

[Megaule]

Re: Lg 65UB950V No Image

So i test only the psb, with mainboard and tcon completly disconnected. I pull pwron and drvon up to 3,5v with 1k resistor. I have all votages, 12v and 24v. The 82v for backlight goes on 72v ca but only for 3-4seconds, the backlight will turn on for this time, then the bl voltage goes to zero and the errorled flashes 3 times!!

[Megaule]

Re: Lg 65UB950V No Image

I tested also the caps on the psb... All ok...

[nomoresonys]

Re: Lg 65UB950V No Image

Kinda seems like a backlight issue.

[Megaule]

Re: Lg 65UB950V No Image

When it is so, then i do not understand why the system don't light up the backlight, and then the system "see" that there is a problem and told the drvon signal and goes in error state. But when i spower on the tv, there isn't a drvon signal, will mean the tv do not get "test" the backlight.... Probably the mainboard is in permanent error status!?!
Excuse my english, but i hope you will understand me....

[nomoresonys]

Re: Lg 65UB950V No Image

Post #11, that pb stand alone test, where you turn on the powerboard, should bring the backlights on, that's why I'm thinking it's problem in backlight circuit or powerboard.

[Megaule]

Re: Lg 65UB950V No Image

Yes in this case the backlight go on for 3-4 seconds then go out... You mean if the backlight are good, so in pb stand alone test they have to remain on, if i understand right...

[Megaule]

Re: Lg 65UB950V No Image

Is there any service manual of the tv or power bord to identify the flashing led error codes??

[nomoresonys]

Re: Lg 65UB950V No Image

Yes in this case the backlight go on for 3-4 seconds then go out... You mean if the backlight are good, so in pb stand alone test they have to remain on, if i understand right...

Yes, affirmative.

[nomoresonys]

Re: Lg 65UB950V No Image

I'll let the others help you with that, I dislike manuals, they make it too easy.

[Megaule]

Re: Lg 65UB950V No Image

How can i test the ledstrips without a specific backlight tester?