LG 50PV400 black vertical lines and twin sections

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Still waiting for my new control board. Thanks tom66 for all the help!

I do have a few of questions though. How exactly does the self test work on the control board? I mean, in my situation, I did the test and I do see the cycling patterns but I also still see the defect (the large black vertical line). What exactly does this mean? Does this mean my main board is good and that the problem is further down the line? What does this test check for?

Also, I could see a flashing green light on the control board. What does this light indicate? Is the blinking typically is some pattern?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

The control board runs a piece of software, normally this software takes each image and breaks it down into the 10 subfields (10SF per 60Hz frame == 600Hz subfield drive.)

Jumpering the connector simply tells the software to ignore the video input and generate its own video. It eliminates the main board and some of the control board as the fault. It's still possible for the control board to be faulty if the test patterns are good, but it's rare. It also eliminates the main board, so if you see the defect on the control board test pattern, it can't be a main board issue.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

New control board didn't fix it. The only thing (besides the panel) that I can even think might be the problem at this point is the ribbon cable between the control board and the XL board. Can I use the ribbon cable from the XR board (it's the only one long enough) to test between the control board and the XL board? The ribbon cable between the control board and the XL board is marked "ES1124" while the one between the control board and the XR card is marked "ES1130".

Even if switching these does fix the panel, where would I pick up a new ribbon cable?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

You could use the ribbon cables, they should be compatible. As for sourcing them, maybe a TV scrapper will have kept some. LG's late model plasmas were roughly the same as each other, so maybe one from a similar model will work too.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

I tried the other ribbon cable. No change - looks the same as before. The thing I keep coming back to, that helps me to believe it's not the panel (even though it probably is), is that it is *exactly* 1/3 of the screen that is affected. Doesn't that seem a bit strange for a panel fault? Obviously I'm very new at this so maybe that is normal but it sure seems odd to me.

I don't even know what else to check for at this point though. Tom, thanks for all your help. You're a gentleman and a scholar!

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Since we have seen faults like these on LCDs (also being the panel -- it's more common on LCDs) it could be that the driver chip is shorted, disabling some control signals, hence why it affects all on that side of the screen (the shared signal is being lost)