LG 47LW6500-UA Screen/Image Quality Problem

[tmhobadcap]

I got this TV from a friend. It could not be turned on. After checking the internet (including this forum), I decided to try reflowing the bga chips with heat gun. The first one I tried is the one covered with a small heat sink, but that did not make the tv work. Then I tried reflowing the main processor which is covered by a large heat sink, and I did make the tv works again. (I removed the heat sinks before reflowing).

However, I found that the screen/image quality is with problem. Please see the attached photos. Did my reflowing damage something and make the screen like this? Can this problem be fixed?

[alfatv]

Re: LG 47LW6500-UA Screen/Image Quality Problem

Most likely the problem is still with main board. But you can ask your fried if this problem was there before or not.
Did you follow reflow profile? If not, it could be too little or too much heat.
PCB could be damaged if it was not pre-baked and if too much heat was applied.

[tmhobadcap]

Re: LG 47LW6500-UA Screen/Image Quality Problem

i got this tv from a friend. It could not be turned on. After checking the internet (including this forum), i decided to try reflowing the bga chips with heat gun. The first one i tried is the one covered with a small heat sink, but that did not make the tv work. Then i tried reflowing the main processor which is covered by a large heat sink, and i did make the tv works again. (i removed the heat sinks before reflowing).

However, i found that the screen/image quality is with problem. Please see the attached photos. Did my reflowing damage something and make the screen like this? Can this problem be fixed?

Forgot 1 more photo.

[tmhobadcap]

Re: LG 47LW6500-UA Screen/Image Quality Problem

Most likely the problem is still with main board. But you can ask your fried if this problem was there before or not.
Did you follow reflow profile? If not, it could be too little or too much heat.
PCB could be damaged if it was not pre-baked and if too much heat was applied.

Thanks for your reply. My friend said "There were no problems I could see... but it did have a similar problem that was corrected about 5 years ago."

I did not follow reflow profile strictly. But I did heat it up slowly. I gradually increased the temperature and at each temperature I stayed there for about 2 minutes. The final maximum temperature shown on my hot air system was 340 degree celisus.

[Nick's Tvs]

Re: LG 47LW6500-UA Screen/Image Quality Problem

Reflow it again, you most likely didn't reflow correctly. make sure to use flux

[tmhobadcap]

Re: LG 47LW6500-UA Screen/Image Quality Problem

I have fixed the image/screen problem. I unplugged and plugged back the connectors connecting the main board and the T-con board, and the problem has gone. Most probably, I did not plug them back properly after reflowing the main board.