LG 50PX1D - Black Bars on Top

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

I probably will have a couple of cables that correspond to a black line. Not sure where one cable is on the screen to where the next cable is on the screen

Any hints for soldering on cable?

Not sure what the acronyms are, what is a COF and an IC?

[tom66]

Re: LG 50PX1D - Black Bars on Top

COF = chip on flex, the "IC" on the flex.
IC = integrated circuit, massively complex circuit compressed to tiny size, not always on COF

Soldering is done like any normal PCB, except that damage to the flex will be fatal to the panel, so be careful!

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

Any recommendations for soldering on the flex as not to damage it?

[tom66]

Re: LG 50PX1D - Black Bars on Top

Don't apply heat for too long, it's fairly difficult to damage, just don't tear it or do something like that.

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

We have progress. I went back and re-soldered the effected areas. A couple were not even attached at one end. I touched the solder gun to the resistors and a couple just moved.

I now have something there (snow) where there was nothing. And it the snow looks ok. However, when the screen is all black, there is some screen burn and still has some blue haze in the effected areas as well as a couple fine red lines as noted in post #3. Any ideas on more improvement? I am working on getting a video source so I can see what video looks like. Pics do not show my current problem.

[tom66]

Re: LG 50PX1D - Black Bars on Top

OK, I will wait until a picture becomes available.

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

Ok...
Apparently I missed a resistor or another came loose. Will fix that shortly.
Note the horizontal line through the middle.
Note the vertical red line and two yellow lines on the top half of the screen.
Lastly, you can see in the fringe the blue in what should be black.

FWIW, the video is low quality off my ipod.

[tom66]

Re: LG 50PX1D - Black Bars on Top

Did you reseat the drivers while power was connected?

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

No. I do not (or at least try not to) work on anything live. Not to say whether someone else did in the past (but I doubt it).

[tom66]

Re: LG 50PX1D - Black Bars on Top

I think the solid pixel lines are bad drivers, which condemns the panel. There's a chance the intermittent solder joint damaged the driver as it is very sensitive to its Va power supply (plugging it in while live can damage the panel for example.)

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

Any suggestions or part it out?

[tom66]

Re: LG 50PX1D - Black Bars on Top

I don't think it's fixable.

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

Well, that is a bummer. Any salvageable parts?

[tom66]

Re: LG 50PX1D - Black Bars on Top

Yeah, you may be able to get $100~$150 for the Y-sus and buffer boards as they are a common failure, I do not like that horizontal black line on the panel though I think it may be a bad buffer board (upper or lower) or loose connector.

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

Are buffer boards worth it to replace? What loose connection should I be looking for? I'll give it one last chance...

[tom66]

Re: LG 50PX1D - Black Bars on Top

Not for vertical lines, only horizontal, and only in rare cases.

[slawson2000]

Re: LG 50PX1D - Black Bars on Top

I still have the horizontal line...

[tom66]

Re: LG 50PX1D - Black Bars on Top

But, you have vertical lines too, right? No point in fixing just part of the problem when it's that bad.