LG LN5700 logo flash then dark screen

[robledjl]

First of all thank you for whoever reads this post. I have to say I'm not a professional but I do have some experience with basic electrical work, enough to not get myself zapped lol so after spending four days reading threads and looking at videos I came to a conclusion that my TV as many others have a burned LED, well to my surprise after disassembling the screen all led's turned on even one that just by looking at it you would think that it's no good. I am attaching a picture to see what you guys think. Like I said all turn on just fine although one is still in question once you see the picture. Any advice will be greatly appreciated.

As you can see it looks like the cover burnt out or cracked.

[robledjl]

Re: LG LN5700 logo flash then dark screen

Well just in case anyone is still looking at this post... I kept looking at the led on the picture above and still searching online for more solutions. What I've noticed is that someone had previously repaired that led, I realized the solder work that it was done and how they used a glue gun to try to hold the led cover, which it didn't work because I found the cover on the corner of the screen. In short... My assumption is that someone tried to fix it before and I'm not sure if they solder it wrong... And further suggestions would be greatly appreciated . like I said all turn on, there are no bad led but turns on and then off.

[robledjl]

Re: LG LN5700 logo flash then dark screen

**UPDATE ** well further inspection it looks like the led although poor soldering job it works, I turned the TV on and it actually stays on the remainder of the time until later on when I turn it off and on that's when it flashes, all led stay lit.. I also checked the voltage in regards to the table listed on the power board and they are all good. I'm confused now, I was really hoping it was a bad led but I think I can rule that out, anyone out there that can lead me in the right direction?

[martino]

Re: LG LN5700 logo flash then dark screen

more info,you clearly bought it used (previous repair). Did it work for awhile and then quit or it has been doing the 2 sec to black right away.
First guess,without any info would be that soldered in led has different specs and triggers the fault button

[robledjl]

Re: LG LN5700 logo flash then dark screen

Thanks first of all for your reply. It was given to me for free. They told me it turns off as soon as they turned it on, once I brought it home it worked just fine until later on when I tried to turn it on again that's when I realized what they were talking about. I could still see the menu very slightly just like the flashlight test. That's when I started reading a lot until I cracked it open and realized all led were working just fine although from the looks of it, it had been repaired before.

[martino]

Re: LG LN5700 logo flash then dark screen

Is this the 42"?
I'd say this is your best option:
https://www.shopjimmy.com/lg-lc420du...ps-1-board.htm

These models and many other LG led tv's are plagued with failing led's.
9 out of 10 times I get a lg here it's the led's . Turning backlight down as much as you can bare will increase life by miles.

[robledjl]

Re: LG LN5700 logo flash then dark screen

This is the 47". Do you think I still need to replace the led strips even though they all turn on even the one that I thought was burnt on the picture?

[martino]

Re: LG LN5700 logo flash then dark screen

I would perhaps test the amperage to the led's per line first.See if one line is giving itself away by drawing more then the others.

[martino]

Re: LG LN5700 logo flash then dark screen

Found something interesting for you
This guy is worth watching!!!

https://www.youtube.com/watch?v=Bf5T2wwtydY

[robledjl]

Re: LG LN5700 logo flash then dark screen

Oh man trust me I've watched his video quite a few times lol the amperage seems to be fine, now that I flipped the TV over to check the strips it seems to stay on, I've turned on and off the TV via the power button on the side and it functions perfectly... I'm really confused now???. Thanks for your replies once again

[robledjl]

Re: LG LN5700 logo flash then dark screen

... Another thing I just noticed, so far the led's stay on. I left the TV on in the garage to see if they will stay on for a while, well it seems like after 30 minutes or so it turns off, I'm wondering if it has a setting that makes it turn on if there is no signal? I then turn it back on and it stays on. I'm still puzzled as to my original problem??

[martino]

Re: LG LN5700 logo flash then dark screen

It will shut off on the no-signal timer.
What voltages are you getting on the 2 test points for the LED's?
"Amperage seems to be fine".....AS in you measured it? If you loop your multi meter into the circuit,you can clearly tell if all trips are pulling the same or if there is one that draws border line enough to trigger fault.
Sometimes by staring long enough at the led's you can see one or two that are a slight different brightness,those would be suspect.
Did you take a super close look at the soldered led? Crappy soldering maybe intermittent good or bad contact?
Knowing the bad rap this model has for it's backlighting I would try the above suggestions as I still believe it to be a led failure. (a fun one as it is not obvious into what strip is teasing you,lol)

[robledjl]

Re: LG LN5700 logo flash then dark screen

Hey Martino! Thanks again for helping me out. I'm not sure if I wasn't understanding you right but I took some pictures to maybe help you understand what I did. Now I'm not a professional but I try to fix things. Lol I tested the + pins as shown on the picture, I get a reading of 76.5 on both with the TV on. I also took a picture of the solder it had been done before, what do you think? Did you wanted me to read the points on the actual strip?

[robledjl]

Re: LG LN5700 logo flash then dark screen

can anyone look at the picture of the LED that had been solder and see if it looks good or should I try to flow it better? Like mentioned before...this TV had been previously repaired before it was given to me. thanks

[martino]

Re: LG LN5700 logo flash then dark screen

I tested the + pins as shown on the picture, I get a reading of 76.5 on both with the TV on.

Did you test like in the video,from 1:20 to 2:20.?

[robledjl]

Re: LG LN5700 logo flash then dark screen

OK Martino, I just got home and played the video again and followed it like you mentioned, I don't have a fluke with a min max option but this is what I got... Right side 058.2 and left side 37.5 but it was not steady it would fluctuate. ???

[robledjl]

Re: LG LN5700 logo flash then dark screen

Does anyone know if these readings are wrong? Bad?

[robledjl]

Re: LG LN5700 logo flash then dark screen

Are you still around Martino?

[martino]

Re: LG LN5700 logo flash then dark screen

ya,been busy.
I'd say both sides should read equal. I have this same model here,screen is gone but i used it as a donor for two others. I will make the backlight complete and measure what mine does.Will report tomorrow what my readings are.

[robledjl]

Re: LG LN5700 logo flash then dark screen

You are awesome brother! I am close to taking it to the recycling center but I wanted to make sure there was nothing else I could do... Im just not too savvy in TV 's. I really appreciate your help even though you are busy. Thanks once again.