LG Nano91 TV Backlights

[Storyteller12]

I have this TV that turns on and shows a pic but there is a line of backlights out.

So I opened it up tests the backlights. Found the 2 leds that are a fault. However these leds measure 20.2v per led. The 2 bad leds work but only measured 9v.

I've never seen leds like this on a tv that measure that high. These are super tiny (I'm guessing that where the nano part of the name comes from.

I planned to replace just the 2 bad leds but never seen a 20v led.

Anyone else have experience with these tv backlights?

[lotas]

Re: LG Nano91 TV Backlights

Rather, it is a matrix LED, consisting of several LEDs.

[Storyteller12]

Re: LG Nano91 TV Backlights

Thanks for the info. Is there anyway to replace just the led? If so where do I buy them. I googled for a 20v led but got nothing.

Appreciate the help

[lotas]

Re: LG Nano91 TV Backlights

It seems to me that it is better to change the entire bar or the whole set at once, because the remaining LEDs will not last long (crystal digrodation has begun), after a short time others will start to burn out.

https://www.ebay.co.uk/itm/175351538101

[Storyteller12]

Re: LG Nano91 TV Backlights

Yea, usually I do replace all. however I’m in the US and nobody has them in stock at a reasonable price. I looked on eBay for a single replacement strip also but nothing. So I was just going to replace the 2 bad ones and turn backlights down.

[Diah]

Re: LG Nano91 TV Backlights

i am afraid there are error at the testing... we do know LED tester had lack with built in ziner at LED.
to be more sure of the reading 20V for the working LED and even the bad one of 9V. i would suggest with normal power on the set..... TV will work with out screen in place... measure with yours DMM at the BL socket each group. and tell how many LEds at each Group

[Storyteller12]

Re: LG Nano91 TV Backlights

Ok, I will double check and report back. Just to mention these led strips light up in 4s at the test points and show 79.5v on the tester also.
But that’s not to say it’s wrong as you mentioned.

[Storyteller12]

Re: LG Nano91 TV Backlights

i am afraid there are error at the testing... we do know LED tester had lack with built in ziner at LED.
to be more sure of the reading 20V for the working LED and even the bad one of 9V. i would suggest with normal power on the set..... TV will work with out screen in place... measure with yours DMM at the BL socket each group. and tell how many LEds at each Group

I measured with DMM while tv was on. I measure 80v. These are wired in groups of 4 leds as I mentioned above.

I also measured the individual led when on and it still reads 20v.

Attached is picture of the bl socket.

[Storyteller12]

Re: LG Nano91 TV Backlights

Here is pics of the tv boards and a closeup of the led driver board as well.
Should have uploaded these from the beginning.

[Storyteller12]

Re: LG Nano91 TV Backlights

Just to further test I removed the bad 9v led from the strip and measured it and still got 9v.

I can’t believe these nano leds run on 20v. That seems crazy to me.

[nomoresonys]

Re: LG Nano91 TV Backlights

I'm a little surprised but not much that they are bad already, isn't it a relatively new tv? guess they are all still making crap.

[Diah]

Re: LG Nano91 TV Backlights

well we can see at the LED driver boards ( blue one )there are 8 channrl . can you tell how many LED unit in total at all strips ?

[lotas]

Re: LG Nano91 TV Backlights

Judging by the photo 128 leds.

[Diah]

Re: LG Nano91 TV Backlights

BTW the one you removed out the strips... please messure it with yours DMM in Diode beep mode... and tell if it is open or there value

[Storyteller12]

Re: LG Nano91 TV Backlights

There are 16 strips total with 8 leds per strip.

[Storyteller12]

Re: LG Nano91 TV Backlights

Ill have to measure with dmm later as I’m not at the office now but I don’t think it measure open as the led lights up but only show 9v on tester

[Diah]

Re: LG Nano91 TV Backlights

i think they are just normal LED from innotek 6.4V

[Diah]

Re: LG Nano91 TV Backlights

There are 16 strips total with 8 leds per strip.

the photo lotas link to us showing 8 strips each 16 led lol..

[Diah]

Re: LG Nano91 TV Backlights

each 4 led from up / down strips or at diffrent postion share same line VLED and ending to one -

[Storyteller12]

Re: LG Nano91 TV Backlights

They split down the middle into separate strips. But effectively it’s 8 strips 16leds.