LG Smart TV flickering screen

[crabn]

Hi everyone,

I got an issue with my LG Smart TV. The screen is flickering on and off. I took a video discribing the issue:
https://youtu.be/2pkUCYydSJU

Do you suggest any solution? Power board, T-con Board, Main board or LED strips

Thank you.

[ReeceyBurger123]

Re: LG Smart TV flickering screen

Great research, good photos, good voltage list, good diagnoses really helped us. Imo the tcon, psu, lcd panel, leds, mainboard and materials used to build the set are faulty.

Jokes aside youve dont nothing to help us at all, start with testing voltages maybe go to my channel and watch my video on the Lg set turning on and off. Gets very annoying when you dont provide us with any info.

[crabn]

Re: LG Smart TV flickering screen

Thank you for quick reply. I'm sorry for my post. Model no is 50LA6970.

Voltages from PSU to mainboard are good. No badcaps as far as I observed. It turned out that flickering screen occurs only when TV is on TV mode. When it's on wifi, it's fine even TV cable plugged in.

So I guess something is wrong with antena/cable input on motherboard or loosing cable associated with TV mode. I will open it soon and inspect them.

Any other comments would be highly appreciated.

[dick_barton]

Re: LG Smart TV flickering screen

Someone else recently had a problem similar to this but when using the HDMI connection which turned out to be poor earthing (grounding). Resoldering the HDMI connector shield on the mainboard solved their problem so perhaps you have a poor earthing problem too. It may be worth while checking the soldering around the tuner and ensure all mainboard screws are firm.

[ReeceyBurger123]

Re: LG Smart TV flickering screen

I agree with DB here, Lg Led sets have issues with lose ground screws and corroded ground pads on the chassis.

[Alastair E]

Re: LG Smart TV flickering screen

Ive had a couple of Vestels do this--A reset cured it...

[crabn]

Re: LG Smart TV flickering screen

Someone else recently had a problem similar to this but when using the HDMI connection which turned out to be poor earthing (grounding). Resoldering the HDMI connector shield on the mainboard solved their problem so perhaps you have a poor earthing problem too. It may be worth while checking the soldering around the tuner and ensure all mainboard screws are firm.

I checked the soldering around the tuner. It is good. I also cleaned the ground connection area on the main board and chasis. It does help a bit but does not solve the problem completely. It is still flickering. Little flickering more frequently and the off - on less frequently.

https://www.youtube.com/watch?v=LM4PXqBAI1w

It turned out to be more serious now. It is flickering on both wifi and TV modes now. It repeated the issue several weeks ago. I fixed this issue by just reseating cables from mainboard to t-con board.

I will upload the pictures later

[Alastair E]

Re: LG Smart TV flickering screen

Go through the Backlight Setting on ALL Inputs--Set to say exactly halfway.

I reckon you got a dodgy LED somewhere--the flickering on say DTV is Maybe because that backlight setting is higher/different from the inputs that work OK...

[crabn]

Re: LG Smart TV flickering screen

Go through the Backlight Setting on ALL Inputs--Set to say exactly halfway.

I reckon you got a dodgy LED somewhere--the flickering on say DTV is Maybe because that backlight setting is higher/different from the inputs that work OK...

I also suspect that there is one or more dying LED(s). How do I test LED with a multimeter?

[crabn]

Re: LG Smart TV flickering screen

I checked the soldering around the tuner. It is good. I also cleaned the ground connection area on the main board and chasis. It does help a bit but does not solve the problem completely. It is still flickering. Little flickering more frequently and the off - on less frequently.

https://www.youtube.com/watch?v=LM4PXqBAI1w

It turned out to be more serious now. It is flickering on both wifi and TV modes now. It repeated the issue several weeks ago. I fixed this issue by just reseating cables from mainboard to t-con board.

I will upload the pictures later

I recent went through this thread. https://www.badcaps.net/forum/showth...ght=flickering

He has a similar issue of flickering. DB also suggested the issue with grounding. So I want to try to ground motherboard and power supply to the chasis.
Can anyone point out where to ground motherboard and power supply to the chasis?

Pictures are of the back of the TV, mainboard, power supply and an unknown board that go to LED strips.

[crabn]

Re: LG Smart TV flickering screen

I recent went through this thread. https://www.badcaps.net/forum/showth...ght=flickering

He has a similar issue of flickering. DB also suggested the issue with grounding. So I want to try to ground motherboard and power supply to the chasis.
Can anyone point out where to ground motherboard and power supply to the chasis?

Pictures are of the back of the TV, mainboard, power supply and an unknown board that go to LED strips.

Here is a picture of back of power supply. I do not see any loose soldering or bad caps. Can anyone help with the location for grounding on mainboard and power supply?

[lukep]

Re: LG Smart TV flickering screen

circle soldering (dots) -gdn

[crabn]

Re: LG Smart TV flickering screen

It seems that this guy at (https://www.badcaps.net/forum/showthread.php?t=42434) got the same issue with me. He fixed it by replacing backlight driver IC on the power supply.

Can anyone point out the backlight driver IC on the power supply of TV?
Thanks

[Diah]

Re: LG Smart TV flickering screen

It seems that this guy at (https://www.badcaps.net/forum/showthread.php?t=42434) got the same issue with me. He fixed it by replacing backlight driver IC on the power supply.

Can anyone point out the backlight driver IC on the power supply of TV?
Thanks

1- you are looking at wrong board, backlight driver are at the middle top covered with metal plate. as your first photo in post 10

2- from the same photo can see the black light are ON always but screen as you said flick .. keep watch from the back of the TV if the back light keep on but only the screen go black..

[crabn]

Re: LG Smart TV flickering screen

Thank you, Diah.
1) You are right. The backlight driver should be at the middle top covered with metal plate. I will take picture when I have time to work on it.
2) The screen go black when back light is off. Screen flicks when backlight flicks. When backlight is off, I can see everything on the screen with a flash light.

[crabn]

Re: LG Smart TV flickering screen

1- you are looking at wrong board, backlight driver are at the middle top covered with metal plate. as your first photo in post 10

2- from the same photo can see the black light are ON always but screen as you said flick .. keep watch from the back of the TV if the back light keep on but only the screen go black..

Hi Diah,

This is the picture of backlight driver board. Can you point out where is the backlight IC on this board?
Please refer to my previous post. Do you think the backlight IC is the issue?

Thank you.