Chosen Solution
Having followed this guide and swapped out my hard disk successfully, i now have a solid black line about a centimetre wide 1/4 from the left hand side of the screen…does anyone have any ideas ? Thanks
Ouch! Thats not good ;-} In the process of removing the display you damaged it. At this point you’ll need to replace it. Here’s a good write up on different LCD problems: Wikipedia - Defective pixel. In your case you have a TAB problem as you cut into the LCD sandwich stressing the connections.
You may also want to check that the plug is all the way in, or the socket to the LCD cable is not damaged in anyway. I’ve had experience where the LCD is perfectly undamaged but the socket where the LCD cable plugs in have been bent a bit out of shape and its not making full contact in turn it created an line down the LCD approximately an inch thick. Once we manipulated the socket it went back to normal again.
Try resetting the PRAM/NVRAM. It may not work, but all it takes is a reboot. https://support.apple.com/en-us/HT204063 Good luck!
I have this same issue with my 27 680MX iMac after swapping drives. I ran the apple hardware test and nothing comes up. I also tried taking a screen shot but nothing shows on the screenshot. Its just one thick black line from top to bottom of the screen. Anyone know if i might need a new display or a whole new motherboard?
