Single pixel vertical line issue

[Danwilderspin]

Hi all

My 2011 iMac 27 has developed this annoying single pixel wide blue line.
mid on a red background it goes black and it’s off completely on a black background.

I know my way around the panels to a degree, a while back i cleaned dust off the white sheet as it had that issue, and on my 09’i changed the backlight leds.

to rule it being the display not gpu or anything else I swapped the controller board on the screens between the 09 and the 11 and vice versa then swapped the screens. Sure enough the blue line moved to the 09...

so my question now is how can I try and fix it? Any setting points everything seems seated well?

many thanks!

 

[Nguyen Duc Hieu]

If you have already checked all flat cables, then

It's the signal board that attached with the LCD panel (the thin dark one).
There is corrosion on the board, very tiny one.
If you can find that corrosion, then you can fix this line. But to keep it last long, professional pressing machine is required.

 

[Danwilderspin]

If you have already checked all flat cables, then

It's the signal board that attached with the LCD panel (the thin dark one).
There is corrosion on the board, very tiny one.
If you can find that corrosion, then you can fix this line. But to keep it last long, professional pressing machine is required.

Thank you - so is the corrosion likely on the ribbon cable going from the secondary board or the actual secondary board? Any ideas on a temporary quick fix? spray contact cleaner around?

 

[Nguyen Duc Hieu]

Thank you - so is the corrosion likely on the ribbon cable going from the secondary board or the actual secondary board? Any ideas on a temporary quick fix? spray contact cleaner around?

Just check the parts thoroughly, in many cases, it's just a bad flat cable. Cleaning the soket, replacing the flat cable may fix.
If you don't know the exact cause, applying solution may just worsen the issue.