LG TV shuts of (70uh6350ub)

[svargo]

I have an LG TV (70uh6350ub) that shut off by itself one day (no video or sound). I turned it back on & it stayed on for about 10 min. then shut off again. Turned is back on & it shut off after about 3 seconds. Since then, if I leave the set unplugged over night it will come on (video & sound) for about 2 to 5 min., then shut off (although the backlight stays on for several sec, to about 1 min.). After that, if turned on, it will shut off in about 2 sec., or not turn on at all.

Took the back off & noticed that the green led on the power board flashes 5 times (continues doing so) once the TV shuts itself off.

I have the service manual, however it shows a power board different from the one I have ( EAY63749303). Therefore the pin out designations are likely very different.

Any help or suggestions? All this started about 1 week out of warranty.

[dskall]

Need good clear pictures of boards and power board to main board connecter.

[Diah]

led indicatore on PCB related to LED BL. so here are your issue.

[svargo]

I will take & post some pics. On the LED BL, is it the electronics that control the BL, or the LEDs themselves? Is there a way to check the LEDs with a test meter without removing the LEDs? Or a way to check the led controls?

[Diah]

upload as requested above focused high resolution Photos on yours Power boards from the top and downside.. so we can assist you with way to make measurements.

[Storyteller12]

It’s the backlights.

[nomoresonys]

do this, when it comes on try turning the backlights way down, if no backlight adjustment then turn the brightness way down and see if the tv stays on longer.

[svargo]

Attached are photos showing 1.the back of the TV, 2 power board, 3. main board, 4. t-con board.

I did reduce the brightness during a previous start up. no real change in how long it is on.

I did notice some heat from the power board area when I still had the back on the tv. stayed heated if I kept the tv plugged in, but not on. could this be an issue?

[svargo]

Just wondered if there was a way to check the backlights/ backlight system without disassembly?

Also, I mentioned the heating because if the power board area is heated (warm) either from turning it on recently, or from leaving it plugged it, it will not turn on (or if it does, only for about 1 second). The set will only come on (2 -5 min.) if it has been setting unplugged for a while. Not a very scientific analysis, but there does seem to be a pattern.

Any help is appreciated.

If additional photos are needed, please advise. As I mentioned the power board on my unit is different from the service manual. Mine has a 28 pin cable to the main board, while the manual shows an 18 pin cable.

[Diah]

upload photo of the power boards from the downside to the area where you have 3 sockets for BL LED to see LED+ on each socket are connected together or not to tell you how to make the measurement.

[captainKKK]

You might find this interesting: https://www.badcaps.net/forum/showthread.php?t=104184

[Diah]

Originally Posted by captainKKK

You might find this interesting: https://www.badcaps.net/forum/showthread.php?t=104184

what you post and advertise at yours links are rubbish specialty your last post #17
wish you learn what are LED and how they work first. sorry i cant give better answer to any hijack threats with rubbish advertisement.

[captainKKK]

[QUOTE=svargo;1130051] said "Just wondered if there was a way to check the backlights/ backlight system without disassembly?"

Svargo asked and I offered what had already been discussed. There is no Hijacking, Threats or rubbish, just opinions. That "rubbish" as you call it was published by the manufacturer. Sorry you are offended, ESPECIALLY by his guide in #17.

[Storyteller12]

There is a safety wire you can cut in the harness and it will disable the tv from cutting off from backlight fault. I would not use the tv like this as it can cause a fire and will kill the other leds from to much current.

You need to reconnect the wire you cut after testing.

It’s the backlights 100% though.

[svargo]

Just got back to this. Thanks all for responding

For Diah, I have this question. Are you saying that I need a photo of the backside of the power board in the area of the backlight connectors? That means I need to remove the power board to take that photo.. Please confirm. I believe the backlight connectors are the "P801, P802 and P803 " on the power board (in the photo I have posted) Am I correct?

The backlights were the last things I had hoped to have to deal with, as I did not want to have to deal with disassembling a 70 inch screen. But on the positive side, they are the only parts currently available for this TV on ShipJimmy.

Also, based on the comments by "Storyteller12" apparently the TV will shut off if there is a problem with the backlights. Does this include the sound? I say this because when the video goes out, the sound does also.

[svargo]

I was reading some similar posts, including one about the same TV. Seems that most folks who have the backlights go out can still see the video using the "flashlight" test, and the sound does not shut off. In my case, the video and sound shut off. I can not see any video using the flashlight test.

I bring this up because I had a computer monitor go out a few months ago. When the screen went dark, I found that I could still see the video if I darkened the room and shined a flash light onto the screen. Turns out it was the cfl backlights not working.

So my secondary question in this matter is why some folks still have video and sound when their backlights fail, but I do not have video or sound?

[Storyteller12]

When the backlights fail in this tv it cuts off.

Some TVs will stay on even with no backlights that’s how you see the picture with the flashlight test and hear sound.

Ie: Roku TVs stay in with no backlights.

[svargo]

So, it seems that all roads lead to the backlights.

I have just started to attempt electronics repair, so I would like to run some diagnostics, to inform future endeavors.

The service manual I downloaded references the correct TV, but show, and had data on the wrong power board. Any help on locating the correct manual? My power board has a 28 pin connector to the MB, the manual I have shows an 18 pin connector.

To Diah, I will take a photo of the back of the power board, and post it. That will help, correct?

[svargo]

Any idea which wire is this "safety wire."