Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

[tom66]

About 3 years ago I fixed an LE40A656 for my parents with the common bad capacitors issue.

Now the TV exhibits another fault, which is rather odd. Essentially any bright part of the image will bleed vertically across the panel although it's more predominant near the top of the panel. Turning the contrast down below about 85 hides the lines except on the menus, which seems to have a fixed brightness.

I have a theory that the panel itself might be aging, rather than this being a tab bonding issue. The bulbs emit UV light which might be damaging the pixel TFTs requiring a stronger or weaker drive voltage. Or it could be related to heat over time - perhaps temperature related.

I am going to investigate changing the VGL voltage (this turns pixels off, I suspect it may be too marginal), if this is not possible I will try reducing AVDD.

[stj]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

i'v seen ghosting / trailing too.
i would check the panel for bad or missing bias voltages.

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Thing is the picture is OK mostly - only bright lines cause the bleeding. If you set the contrast low they never occur. Apparently the issue occurred slowly and got worse over time, which is interesting.

[martino]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Pictures of fault,boards front/back,ID off all boards etc.. Do you have a DMM? Any knowledge of electrical/wood/metal? Cooking?.... lmao.........

[stj]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

lol

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Long delay in posting.
Going to have a look at this thing soon.
Found that increasing AVDD (by loading feedback point) made fault worse.
Going to try decreasing it.

[cliff_hootarski]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Too funny, Martino!

[debugger]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

I have a LG LN40A630M with the same symptoms. It gets a decent picture with the contrast turned down. Do these pictures look like your fault.

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Yep, that's the same as what I'm seeing. Haven't had a chance to hook it up to a source properly yet.

[Flipk614]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

...

[Flipk614]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Okay here are some pictures of mine.

1-Tv right at startup
2-After about a minute in PC mode
3-Close up of lines in PC mode after 1 minute
4-Xbox guide Hdmi after 3-5 minutes
5-Cable after 3-5 minutes
6-Back of tv
7-Tcon board LJ94-02853

[debugger]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Tom, Badcaps veteran truep told me he fixed a sony with similar problem, with a main bd.

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Different fault, I think. These are panel faults.

[Alastair E]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Hey,--Tom.....

You know what you need to do.....

Take the set to a TV Repair shop! Haha!

Have you tried a T-Con out of curiosity.....?

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Not going to bother with a t-con. I know it's panel related but maybe I can get some life out of it.

[debugger]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

A t-con did not fix my set.

[Shinju]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Service menu, run the test patterns and see if this happens there.

[tom66]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Can't do that on A656. But it is panel failure, no way for it to be anything else. After a few TVs, you can tell when a Samsung panel has died!

[Flipk614]

Re: Samsung LE40A656 vertical line bleed, ideas about fix (panel ageing?)

Tcon didn't help mine. Helped a little. I'm gonna tear it down again and check out the tabs this weekend with the help of component cooler and hair dryer. Any way you can rule out the bad panel. Still got my hopes up on this one. Hate to see it go.