LG 49LF5500-UA Video Crosstalk

[RDC55]

Hi,

I am working a LG 49LF5500-UA that belongs to a friend of a friend - something constructive to do while mostly staying at home during these crazy times.

History - TV would attempt to power up with just a repetitive quick flash of the LED - replaced LED strips and now powering OK

However, there is a video problem that I am not sure if it existed before or if it was induced during the LED strip replacement. The attached picture shows the video problem, and it is weird in that it cycles from good to bad approximately every two seconds. If you look at the attached bad video capture, you can see where the apps displayed on the top portion of the screen show up on the bottom inverted and mirrored.

So I was thinking some type of crosstalk or bad main board, but wanted to check in with the sound advice I have received here in the past on what this might be.

Thanks

[yokoono]

Re: LG 49LF5500-UA Video Crosstalk

Enter the service menu and reset to factory settings.

[RDC55]

Re: LG 49LF5500-UA Video Crosstalk

OK, thanks for the reply, I did try the factory reset found under options and no change.

I need to add that I stated from bad to good in the initial post. I should have said from bad to almost good. The reason being is when the screen clears the mirrored image / distorted video that cycles every two seconds on the bottom there is still one horizontal line that is not behaving and has no video. The line is located right at the very top of the distorted section.

My first thought on that would then be a panel problem, but what would seem odd is that the mirrored / distorted section is approximately 7.5 inches of the vertical height of the screen. The total height is approximately 24.25 inches. I was kind of guessing that the horizontal line panel drivers would be divided into equal sections, so the numbers would imply either a partial failure or my logic is wrong. I was also thinking it was much more common to have total failure of the horizontal line drivers. Note also no COF devices are visible on the panel edges, so I suspect they are built into the panel.

[ernest79336]

Re: LG 49LF5500-UA Video Crosstalk

I have a lg 47LH50-UC I want to do a factory reset on it but when i go to options its not listed and i didnt see it in the service menu Please help if you can!

[Davi.p]

Re: LG 49LF5500-UA Video Crosstalk

ernest don't use other one's thread to post your problems, open a new thread!
To the OP: this is a panel fault and difficult to solve, but can be solved 95% of cases, it belongs to bad gate drivers. i'm almost sure the fault is born by the same reason of the bad lamps, a spike from the electrical source.

[RDC55]

Re: LG 49LF5500-UA Video Crosstalk

Just to finish up on this one and not leave the thread hanging.

I never could get past this being just a panel failure and most likely a row driver IC has been damaged causing the failure. This panel does not have COF row drivers but rather has the drivers built into the panel. The only option was to add tape to the panel ribbon cable flex at the TCON to disable that side and eliminate the shadowing, however this also created poor video with slightly visible horizontal lines and one dead horizontal line, which is likely the point of failure on that side.

[RDC55]

Re: LG 49LF5500-UA Video Crosstalk

Well I was wrong again in the above post. I have had this TV sitting around for quite some time and decided to look into adding tape to the ribbon cables one more time. On this attempt I was more successful and ended up with a picture that is quite acceptable. The only noticeable defect is the one horizontal line about 2/3 of the way down, and even it is not that noticeable anymore.

The attached picture of the TCON shows where the tape was added. It is covering the 2nd through the 12th pin.