LG 42lb650v single vertical stripe - faulty panel or board ?

[Dannyx]

Good day folks. I got this LG 42lb650v which I believe has a faulty panel: upon startup, the LG logo shows up briefly but then quickly fades into what you see in the picture - a single white stripe in the middle of the screen which "glows" towards the edges. Of course I tried the basic stuff: removing the bezel and inspecting the buffers. They all seem OK physically (no spilled liquids or obvious damage) and all the COFs get rather hot when on, but no matter how I jiggle them around, I cannot get the picture to come on. The only way I ever got half a screen to show up was by removing one of the flex cables and even then there was nothing on the other side, however when I touched the flex I just removed with my hand, there was a fairly clear picture showing up on the other side. This trick doesn't work the other way around: if I swap the buffers around and touch the OTHER cable, I get nothing.

When the guy brought it in, I let it run for a few minutes while I was doing the paperwork and occasionally the picture would come in clear, flicker a few times then die again...No caps are shorted on the main board or the buffers...is this a dead panel or a faulty board ? Perhaps something coming loose and occasionally making contact due to heat ? Not much to see on that board either: it's just the large CPU and (what I believe is) a gamma IC - if there's a fault, it's most likely in that large IC and I believe reflowing it would be fairly pointless. If anything, it could make the TV no longer boot AT ALL which would be a friggin' disaster....What do you guys think ? I wouldn't risk buying a board just to discover the panel's dead....cheers.

[tom66]

Re: LG 42lb650v single vertical stripe - faulty panel or board ?

I'd say panel.

You can try heating up the COFs with a heat gun, I was able to repair a single vertical line fault on a panel before doing that, unfortunately it failed a few days later so I suspect the fix is difficult to make permanent.

[R_J]

Re: LG 42lb650v single vertical stripe - faulty panel or board ?

I would remove the plastic bezel and check the lower part of the lcd screen, I bet the screen was cleaned and the fluid ran down and corroded something
Look at the lower part of the bezel also, you might see water stains in the dust

[Dannyx]

Re: LG 42lb650v single vertical stripe - faulty panel or board ?

I would remove the plastic bezel and check the lower part of the lcd screen, I bet the screen was cleaned and the fluid ran down and corroded something
Look at the lower part of the bezel also, you might see water stains in the dust

Already did that (see the first part of my post) and although there was no corrosion or serious damage, I could see even before removing the bezel that there was definitely some foreign matter on the lower lip of the frame...something like cheese puffs or cornmeal...who knows. The weirdest thing is that I found an USB dongle on the inside of the set...not just flopping around inside the case, no no - it was tucked UNDER the metal shield that covers the buffers...imagine that :| I have no clue how it managed to end up inside (UNDER that shield no less) ! I can't even theorize how it fell in in the first place, since the TV doesn't have any large holes or vents and it's fairly flat like TVs are nowadays, so it must've taken whoever slipped it in there quite some effort and "dedication"

[R_J]

Re: LG 42lb650v single vertical stripe - faulty panel or board ?

I missed that part at the top about the liquid, I bet this has a tab bond issue and the dongle was placed there to push against the cable or something for quick sale.

[Dannyx]

Re: LG 42lb650v single vertical stripe - faulty panel or board ?

I missed that part at the top about the liquid, I bet this has a tab bond issue and the dongle was placed there to push against the cable or something for quick sale.

Hey you're right....never even considered the possibility of that being a "fix", although it was on the metal chassis, not actually pressing on anything. Funny thing is that the guy said he bought it new, although that may not be true of course. In that case, looks like it died for good now, because no amount of nudging or pressuring that panel caused it to display anything.....