LG 50PS8000 Flickering and intermittent Double Image

[waheed159]

Hi There,

I have a LG 50PS8000. The tv has a flickering picture with an intermittent double image appearing on the bottom half when it flickers, also some 1 at the bottom and 1 on top orangish flickering horizontal lines. I thought it would be the control board issue so I replaced it bought from eBay but the problem stays the exact same. I have attached 1 still from a pattern scan ( Video link below). Could the replacement control board also be faulty (was not new). I dont know if not having horizontal white lines in the pattern mean Y Buffer is gone? I would appriciate any help. Thanks.

https://www.youtube.com/watch?v=J5IksM62_p8

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

I have now checked all the pins on both the Y Buffers and none of them are short. Does this mean that the Y Buffer is not faulty. What else could cause this problem? Please someone help.

[dick_barton]

Re: LG 50PS8000 Flickering and intermittent Double Image

Have you checked that all your voltages are within spec. VS, VA, VE, VSC, however they are labelled on the board.

[Nick's Tvs]

Re: LG 50PS8000 Flickering and intermittent Double Image

You are looking at an issue with your main board or logic board. Please take pictures of those two boards so we know what we are looking at.

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

The Voltages are all good, have checked them all to be correct using the DMM twice. I will take the picture of the main board tomorrow but here is the picture of the Logic Board which I already have tried replacing with absolute no change whatsoever. Thanks for the input guys.

[Nick's Tvs]

Re: LG 50PS8000 Flickering and intermittent Double Image

Ok wonderful. Now in order to confirm that your issue lies with your main board we will want to activate the ext auto gen on your logic board. This is going to bring up a test pattern on screen. You will want to perform this with the main board disconnected from circuit. If the test pattern appears on screen properly without lines, it will confirm that indeed your issue is coming from the main board.

Now the picture of your logic board ebr63280301 is a great picture, however the auto gen is very different than I am used to seeing. Yours is labeled on the lower left side of the board where as most often I see it on the lower right with 2 test points that need to be shorted to one another. Such as this board shown in the link below

http://assets.shopjimmy.com/media/ca...8101-top_1.jpg

Because of this I am not 100% sure how to proceed further with this test. You have however replaced this board already and even though it is possible, it is unlikely you have received a replacement board with the same failure.
I do think at this point that you have a bad main board however I am not sure how to go about proving it in this scenario.
What I can tell you is that if you have proper voltage output from the power supply, and your sustain boards, then your issue is going to lie with the logic or the main board.

I would also suggest cleaning the ribbon cable called the LVDS cable. It is the one that links the main board and the logic board. I have seen it incorrectly plugged in and cause line patterns on screen such as the pictures you have posted above.

[Alastair E]

Re: LG 50PS8000 Flickering and intermittent Double Image

Y-SUS board fault.--Defo!

(one of the small buffer-chips on the Y relaying data to the y-buffer board)

[Nick's Tvs]

Re: LG 50PS8000 Flickering and intermittent Double Image

Oh man, I just re-read the entire thread. I misread your original post. Sorry about that I thought that the lines you showed us were what you got on regular picture, not from the test pattern. If you have lines like that from the test pattern itself, then your main board is not at fault. I also thought you said that all your voltages were steady but you meant out of the power supply and most likely have not checked output voltage from your Y or X like I thought you had.

APOLOGIES about the misunderstanding.

Definitely test the output voltage of your Y-sustain. Do you get fluctuation? We are going to want to check that VSC voltage on the Y-sustain

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Oh man, I just re-read the entire thread. I misread your original post. Sorry about that I thought that the lines you showed us were what you got on regular picture, not from the test pattern. If you have lines like that from the test pattern itself, then your main board is not at fault. I also thought you said that all your voltages were steady but you meant out of the power supply and most likely have not checked output voltage from your Y or X like I thought you had.

APOLOGIES about the misunderstanding.

Definitely test the output voltage of your Y-sustain. Do you get fluctuation? We are going to want to check that VSC voltage on the Y-sustain

Hi Nick,

I checked all the Volatges on X, Y and the Power supply and they are all good. Was a bit confused when I read your earlier post lol. I will get a couple more pictures up of the actual lines that flicker. The picture from the pattern in my 1st post from the test is unusual as its usually a grid with loads of equal squares (Horizontal and Vertical lines) and not just lines running from top to bottom (Vertical). I am not sure what is causing this discrepency. I have a link to the video of the test in my 1st post also and you can see the flickering horizontal line in that video towards the bottom of the screen.

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Here are a few more pictures that show the flickering line at the bottom and the double image. Also a picture of the main board. Its either Y Board, Main Board or the Screen itself but how can I determine what it is?

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Anyone got any more suggestions?

[Nick's Tvs]

Re: LG 50PS8000 Flickering and intermittent Double Image

Just want to confirm, but you have already disconnected the main board from circuit and done a pattern test with the Logic board to rule out the main board correct?

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Just want to confirm, but you have already disconnected the main board from circuit and done a pattern test with the Logic board to rule out the main board correct?

Yes this has been done correctly with the main board disconnected and I guess this would rule out the main board being faulty. The video link for the test is in the 1st post.

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Y-SUS board fault.--Defo!

(one of the small buffer-chips on the Y relaying data to the y-buffer board)

Hi There,

Could you explain a little bit more and have you diagnosed this fault before? Thanks.

[ReeceyBurger123]

Re: LG 50PS8000 Flickering and intermittent Double Image

Replace Ymain, dont see what more he could say Ive also had this on a PS3000 Ymain fault.

[waheed159]

Re: LG 50PS8000 Flickering and intermittent Double Image

Replace Ymain, dont see what more he could say Ive also had this on a PS3000 Ymain fault.

Thanks. I have ordered a Y Main. Hope it resolves the issue.

[fpegman]

Re: LG 50PS8000 Flickering and intermittent Double Image

Did replacing the Y Main cure the problem please

[akavintz]

Re: LG 50PS8000 Flickering and intermittent Double Image

It would be super helpful to know if that fix cured the problem?

My 50PS8000 has just developed a flicker with a red line across the bottom.