2.0GHz, 2.3GHz, or 2.6GHz quad-core Intel Core i7 processor (Turbo Boost up to 3.8GHz) with 6MB shared L3 cache.

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Weird LCD or backlight issue

I have a weird LCD/backlight issue - a brighter line on top of the screen, see attached photo. It also seems to me that maybe the screen brightness is lower than it should be, i.e. it's not the line brighter, but the rest of the screen is darker, but I do not have a similar model to compare.

Block Image

The line goes from the left edge to the right edge, but isn't fully parallel to the top edge - it's couple pixels wider on the left. Other than this, backlight seems to be uniform across the screen.

Service centre says it's a fault in the display, not the main board. Does anything in the LCD/backlight structure suggest how this can happen?

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You'll need to connect an external display to be sure here whats happening. If the external image looks clear you have a problem within the internal displays logic. If the image look the same then the GPU logic is having issues.

I'm not sure your issue is the internal display its self, but the connection on the logic board. To me it looks like a signal leakage issue as you are clearly getting a herringbone pattern thought the image as well.

I'm suspecting corrosion damage here. Did you get your system wet at some point?

Update (09/09/2016)

As you noted there was liquid damage is it near the Thunderbolt chip or the ribbon connector?

Review this image you'll see the Thunderbolt chip is green outlined on the far Right: MacBook Pro Retina - logic board (top side) You may need to pull the logic board to look at the other side: MacBook Pro Retina - logic board (bottom side) the area of concern is the top left here.

The issue is the displays data signaling between the Thunderbolt chip and the internal display its self (pathway) not the backlight circuit. But, the backlights power lines could be the source of the leakage signal into the displays data signal as both go though the same ribbon connection pathway.

I would start off cleaning off the corrosion staining as the salts within the material is conductive enough to distort the signal. I would also make an effort to clean the internal displays ribbon and the ribbon connectors contact surfaces as often I see this is where the displays signal is being altered.

Its possible the ribbon cable is damaged here which would require replacing the display assembly as trying to replace the ribbon cable alone is just not practical in this series.

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Thanks Dan. The external display is fine. Service centre tested with a good "internal" display and it was fine too. However they found minor liquid damage on the board, but again, it was fine with another display (can be the display side of the connector though). So you think it's a problem in the signal path, not the backlight? Unfortunately it seems most likely I'll have to replace the display anyway, so I'm mostly just curious what can be causing such effect.

I'm not sure (not seeing) what pattern you're talking about, apart from the normal lcd/camera sensor interference.

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Thanks again, I'll try to check. One thing I forgot to mention is that this bright line is visible from the normal viewing angles but nearly invisible if viewing from far up/down or sides.

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That doesn't matter, you're just seeing an optical illusion.

The effect is called Moire Effect. In this case it's the negative effect as the pattern and the alignment of the polarized light waves cancel out each other (think White Vs Black here).

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