tanventure

macrumors newbie
Original poster
Jan 17, 2013
27
3
Picked up an iMac early 2008 20" recently, installed a 240G SSD, OS X Ei Capitan, with 4G RAM, worked very well, however, I found there were color vertical lines on screen.

Vertical patterns are fixed in color and horizontal positions, never changed. On normal screen of a desktop, 6 color vertical lines, see the 1st image below. Noticed that they are hardly noticeable when using Safari browser, see the 3nd image below.

Surprisedly, I found if I captured screen photos with Mac screen capture utility on 2008 20" iMac, inspected them on another Mac, then there were no vertical lines at all, see 2nd image below. So it seems that the vertical lines were CAUSED by faulty display panel because the screen captured images supposedly are images stored in the image buffer of the graphics card, right?

Wonder if the defect vertical lines are caused by faulty graphics card/display panel/data cables? Any suggestions/comments/thoughts are welcome!

Thanks in advance for sharing

1-st image, on a normal desktop screen, 6 color vertical lines
Unknown-6.jpg


2nd image, screen captured with Mac's screen capture software on 20" iMac, then displayed the image on another iMac, can't see the 6 color vertical lines!
screentest2normal.png


3rd image: On safari web page, 6 color vertical lines (hardly noticeable, especially on white background of a web page, mobile phone captured, displayed on 20" iMac)
Unknown-7.jpg
 

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Last edited:

Nguyen Duc Hieu

macrumors 65816
Jul 5, 2020
1,173
292
Ho Chi Minh City, Vietnam
This issue is common in the home-use TVs.
A very small part of the defected TVs can be repaired simply by cleaning and re-seating the signal cable (flat LVDS cable) and the V-sync cable. Cables are cheap.
If the LCD control board is toasted, it's a real nuisance to find a spare one.
 
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Analias

macrumors regular
May 13, 2019
134
47
Video card errors are uniform and repetitive. Lines like this are not gpu related. Unfortunately these lines are from a faulty lcd panel, usually related to the bonding on the ribbon cables deteriorating due to age or moisture, and not repairable.
 

tanventure

macrumors newbie
Original poster
Jan 17, 2013
27
3
Video card errors are uniform and repetitive. Lines like this are not gpu related. Unfortunately these lines are from a faulty lcd panel, usually related to the bonding on the ribbon cables deteriorating due to age or moisture, and not repairable.
I am going to use an external monitor to see if there are vertical lines on it or not, this way may help to determine if the lcd panel is faulty.

Thanks you all for sharing
 
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throAU

macrumors 604
Feb 13, 2012
7,063
4,834
Perth, Western Australia
Video card errors are uniform and repetitive. Lines like this are not gpu related. Unfortunately these lines are from a faulty lcd panel, usually related to the bonding on the ribbon cables deteriorating due to age or moisture, and not repairable.

Not always, my 2011 MBP died with a vertical line similar to these a few months before the display adapter died.

I know it was the video card because it only did it when the discrete GPU was activated, the machine still runs 100% fine today when using the intel integrated.
 

diannetrussell

macrumors newbie
Jul 5, 2010
6
0
Australia
I'm puzzled. If it was a faulty LCD, then the lines should be across everything on the screen? But finder windows and all app windows that are displaying on the screen don't have the lines - they go behind. Plus as Tanventure says you can't take a screen shot of them because they don't show up. I had to take a photo of my screen with my iphone to show you that my 2 blue and 1 red vertical lines are behind the windows. (and it's not the desktop picture, as that changes all the time). Can someone please deepen the clarification of what's going on behind the scenes (no guessing)?
 

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Analias

macrumors regular
May 13, 2019
134
47
The lines are not behind the window. The pixels are red, green and blue, and in the blue lines the red and green are faulty. In the red line, blue and green are faulty. On a white screen you will see no lines as no pixels are active. On a black screen when all colours are supposed to be active you see the lines.
 

diannetrussell

macrumors newbie
Jul 5, 2010
6
0
Australia
The lines are not behind the window. The pixels are red, green and blue, and in the blue lines the red and green are faulty. In the red line, blue and green are faulty. On a white screen you will see no lines as no pixels are active. On a black screen when all colours are supposed to be active you see the lines.
Thank you very much, Analias, for that precise explanation.
 

Analias

macrumors regular
May 13, 2019
134
47
No worries. I actually got it the wrong way around though, all colours on make white, all colours off make black. I am not an expert how how lcd's work, but I do repair computers professionally,so I have enough understanding to know that your problem is the ribbons bonded to the lcd panel.
 
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Nguyen Duc Hieu

macrumors 65816
Jul 5, 2020
1,173
292
Ho Chi Minh City, Vietnam
Anyway, it's not a job for amateur.
Fixing the flat cable of the LCD screen require a professional machine.
Check the below video (12th min) and you will see it's not cost effective to fix.
(the guy in the video said the fixing cost was equal to 30~50$, but that's the price for 3rd world countries like Vietnam)
 
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