LG 42LD550 picture scrambled

[ChiefDJ]

I bought this TV new about 3 years ago and it has worked great until about 3 weeks ago when all of the AV inputs stopped working. I get sound from anything hooked up through AV or composite but no picture. Anything hooked into HDMI still worked fine though.

Then tonight as we were watching TV after it had been on for about an hour, the picture went scrambled with horizontal and diagonal lines (see attached pictures). Still get sound, but the picture is messed up on everything, even the TV menus. I've unplugged the TV for over an hour and when I plugged it back in there was no change.

I've been looking at replacement mainboards and there are NONE available anywhere. (can't believe it).

Anyone have any suggestions for what I can look at?

[IMG][/IMG]

[freakaftr8]

Re: LG 42LD550 picture scrambled

Wow that's an interesting one. Definitely mainboard related. Since the tcon is built into the mainboard it's harder to diagnose what on the board is bad but start with heating the board with a hair dryer to start. See if it gets better

[tom66]

Re: LG 42LD550 picture scrambled

Had one like this before - similar model - turned out the TV had a 720p motherboard installed (or configured as such) in a TV with a 1080p panel. It could also be possible that the configuration EEPROM is corrupted.

[ChiefDJ]

Re: LG 42LD550 picture scrambled

Tom,

I read the thread you are talking about, but there is no way it has the wrong board in it. I bought it new and it has worked fine for over 3 years. The picture just went scrambled all the sudden as we were watching it.

If the EEPROM has become corrupted, what would I do about that?

[multimeter]

Re: LG 42LD550 picture scrambled

scart out to another tv,picture the same?,if it is ,mainboard fail,im guessing the video chip is getting toasty,havent seen this kind of fault relating to t-con board before

[multimeter]

Re: LG 42LD550 picture scrambled

Tom,

I read the thread you are talking about, but there is no way it has the wrong board in it. I bought it new and it has worked fine for over 3 years. The picture just went scrambled all the sudden as we were watching it.

If the EEPROM has become corrupted, what would I do about that?

a new pre-programmed eeprom,or a blank with the correct firmware,i dont think this is eeprom related though

also,does it affect the menu screen?

[ChiefDJ]

Re: LG 42LD550 picture scrambled

a new pre-programmed eeprom,or a blank with the correct firmware,i dont think this is eeprom related though

also,does it affect the menu screen?

Yes it does. I can see the menu coming up because the colors and different lines change, but it is also scrambled.

[multimeter]

Re: LG 42LD550 picture scrambled

Yes it does. I can see the menu coming up because the colors and different lines change, but it is also scrambled.

and does pic change when scarted out to another tv?

[ChiefDJ]

Re: LG 42LD550 picture scrambled

and does pic change when scarted out to another tv?

I haven't tried this. How would I do it? Could I try connecting my laptop to the RGB port? Would this accomplish what you want to look at?

[multimeter]

Re: LG 42LD550 picture scrambled

I haven't tried this. How would I do it? Could I try connecting my laptop to the RGB port? Would this accomplish what you want to look at?

keep the tv your fixing on,use a scart cable to connect to another tv,and select the right channel,if your mainboard is working the second tv will have a good picture-menus etc,if the picture is the showing the same fault on the other tv,your mainboard has failed

[ChiefDJ]

Re: LG 42LD550 picture scrambled

keep the tv your fixing on,use a scart cable to connect to another tv,and select the right channel,if your mainboard is working the second tv will have a good picture-menus etc,if the picture is the showing the same fault on the other tv,your mainboard has failed

I dont have a scart cable or another TV to connect it to. ANything else I can try?

[multimeter]

Re: LG 42LD550 picture scrambled

I dont have a scart cable or another TV to connect it to. ANything else I can try?

you could try laptop,vga on tv?,rgb?

[minishotglass]

Re: LG 42LD550 picture scrambled

OP can I get an update on the solution? Running across the same issue and about to order a replacement main board. Thanks.