LG 50LA6205 Bad Backlight and Bad Panel

[neilc6]

This TV had a logo flash on plug in which is symptoms of a bad LED backlights. Replaced 4 shorted LEDs and now getting horizontal lines. Tcon ribbons connected one at a time show both vertical and horizontal lines with one side. Confirm this is a bad panel before I scrap this tv?

[Andrew F. Ali]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Yes...I see a bad panel.

[Davi.p]

Re: LG 50LA6205 Bad Backlight and Bad Panel

With some work it may be salvaged.. many methods on the field to try.. the easiest one to remove the side tab where the problem starts... also masking with tape on tcon can be tried..

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

No side tabs. Pushed down the tab bonds on the bad side with no change. Scrapped the TV already. Thanks for the input.

[alas3376]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Bad panel

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Thanks Davi.p! Was ready to take the TV to recycling and decided one last attempt with the tape method on the tcon ribbon after reassembling the TV. Luckily none of the parts sold yet on ebay. On the side that showed lines (right), I blocked off around 20 pins on the leftmost side and it worked!!

[budm]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Good works! Lets see how long it will last, at least it is working for now.
Can I get good clear pictures of the T-CON board so may be I can see what those pins are for.

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Sorry, not the best focussed since it was for the ebay listing. Don't want to take the tv apart again since it has been reassembled about 5 times and I've already busted some plastic tabs.

[budm]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Thanks for the pictures, at least I can read the PCB and PCBA numbers so now I can go to shopjimmy to get good clear pictures.

[Davi.p]

Re: LG 50LA6205 Bad Backlight and Bad Panel

OK, where do you have found instructions on how to block signals? I have tried with my 50 inch Hisense w/AUO panel but the result is not perfect, the line still persist due to some gate drv outputs maybe shorted that keep the opposite output low or high, the bigger part of defect is disappeared.. the outer part of the flat is usually reserved for clock signals to the gate drivers.. In mine i have blocked only one signal that disables all the faulty side gate drv, but i will try block others.. maybe it's necessary also to block VGON/VGOFF

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Saw two youtube videos before about putting tape on the tcon ribbons. One wasn't really clear what he was doing. Tape is actually used to block the pins and not to apply more pressure to the contacts. Another one I recall was to vary the pins blocked and location. Mainly trial and error with the location and width of the tape. I'll see if I can find them since it was awhile ago.

I fixed a Samsung before blocking just a few pins.

https://www.badcaps.net/forum/showthread.php?t=50646

[Davi.p]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Yes i saw a shopjimmy picture, them are all the gate driver related signals,except Vcom, Vcomr_FB that maybe better to leave connected, i will check..

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Here is one video

https://youtu.be/j7vl7-vZEL8

[Davi.p]

Re: LG 50LA6205 Bad Backlight and Bad Panel

yeah i knew that video..

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

2 lines intermittently came back along with a pattern across the whole screen. I replaced the scotch tap with electrical tape and will run for a few days to see if it comes back.

[Gdog215]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Is your tv still working today?

[neilc6]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Tv came back recently. Another backlight failed even though all inputs were set at 60/100. Repaired and back up and no lines. I would exoect it to last as long as the side tab removal fix.

[RJARRRPCGP]

Re: LG 50LA6205 Bad Backlight and Bad Panel

What? Another re-badged Sharp panel?

[Davi.p]

Re: LG 50LA6205 Bad Backlight and Bad Panel

Hi neil, i suspect your customer has mains power line disturbances, next time i suggest you to protect all the screen (backlight and tcon/panel matrix) with TVS diodes or varistors and check the backlight driver's power semicon for cracks in solders and esr of the output el.caps. The suppressors must blow a fuse so your work will be easy and cheap in replacing it.. Bye.

[mmartell]

Re: LG 50LA6205 Bad Backlight and Bad Panel

What is theory on this type of repair ? I mean, how are these parts of the panel still displaying an image when the signal containing the image information is being blocked with tape ?