LG 42LE4500 No display

[Ivan Goh]

Re: LG 42LE4500 No display

Probably means the output above or below it is supposed to be 20V, normally PWR (meaning POWER ON) is >2V for on, <0.5V for off.

Hi bro,
I've done some measurements on my 42LE4500-TA board,
but i'm not so sure if the voltages are normal or not..

pls see attached pics..
Hope to get your precious advice..
thanks!

[nomoresonys]

Re: LG 42LE4500 No display

Hi bro,
I've done some measurements on my 42LE4500-TA board,
but i'm not so sure if the voltages are normal or not..

pls see attached pics..
Hope to get your precious advice..
thanks!

https://www.youtube.com/watch?v=4v8DcqCNG4A good video on testing HEED the HIGH VOLTAGE WARNING.

[budm]

Re: LG 42LE4500 No display

Hi bro,
I've done some measurements on my 42LE4500-TA board,
but i'm not so sure if the voltages are normal or not..

pls see attached pics..
Hope to get your precious advice..
thanks!

https://www.badcaps.net/forum/attach...0&d=1519575672
Are these Voltages measured with ref. to chassis GND?
You have 12 LED strings and 12 LED controllers circuits.
If the readings are done with ref. to chassis GND, then it looks like you have some bad LED strings.

BTW, the readings are missing on this one: https://www.badcaps.net/forum/attach...9&d=1519575672

There are 24 pins but you only show STBY condition of only 12 pins and only 12 pins of the ON condition.

[Ivan Goh]

Re: LG 42LE4500 No display

https://www.badcaps.net/forum/attach...0&d=1519575672
Are these Voltages measured with ref. to chassis GND?
You have 12 LED strings and 12 LED controllers circuits.

Hi,
Yes, i measured it with ref. Chassis.
do u know are the measurements voltages correct?

u mentioned about the 12 LED Strings/Controller circuits,
are they the likely root-cause for the failure...?

[budm]

Re: LG 42LE4500 No display

So far it looks like some of the LED strings have have high resistance which are probably due to bad LEDs.

[Ivan Goh]

Re: LG 42LE4500 No display

Oh, really appreciate your prompt guidance..
do u know how should i dismantle to measure these LEDs...?
is it at the top side of the TV?

[budm]

Re: LG 42LE4500 No display

If I were you I would get one of those LED backlights tester, it is worth having one just to give you some idea if some of the LED strings have open circuit or not.
Youe LCD panel for your TV version looks to be made by LG, not AUOP as used in other version of the same model.
There is sticker on the LCD panel model so you can look up and see what kind of LED strips are used in your panel.

[Ivan Goh]

Re: LG 42LE4500 No display

oh, sounds great.
pls guide me with some links or pics...
I'll see if u can get one in my country....or online.

[budm]

Re: LG 42LE4500 No display

Just go to EBAY and type in 'LED BACKLIGHTS TESTER' in the search box.

[Ivan Goh]

Re: LG 42LE4500 No display

OK thanks. I've just googled and found it too.
see attached pic, are these the 12 measurement points?
do i measure with respect to chasis GND?
do u know what is the ideal resistance(during OFF),
or what are the correct voltage(during ON)...?

thanks..

[budm]

Re: LG 42LE4500 No display

When you get the tester you will have to remove the White and Black LED connectors and then probe the Anode pin and Cathode pin of each LED string with the LED tester.

[freakaftr8]

Re: LG 42LE4500 No display

I built one out of a laptop power supply. 19.5v across each led strip. It's dirty but gets the job done.