Colorful vertical lines on 17"

Try a new tcon board and see if that helps.

Colorful lines usually represent video problems. You will need to take your iMac to an Apple certified repair store to have it fixed. It's an advanced job that can only be done with the help of special equipment.
Good luck.
Tech from

Mac Repair Mississauga Apple MacBook screen repair Service MacBook pro...

Bad LCD screen you need to change it

Well .... If I remember right if you hold down the D key it will do just that... maybe the key is stuck

Your LCD is failing. with some models Apple has been known to cover this problem, even when its as old as yours. My suggestion is to call 1800MYAPPLE and ask them if there is any sort of special coverage for your model. Be sure to have your serial number ready for them.

Hi this is a known problem and will terminally get worse with the only solution being to get a new screen being over £300's.
heres someone who could help you http://www.gumtree.com/london/54/66321154.html

Are they vertical?If so the display needs to be change.This is a known problem with this model.I just recently changed adout 29 of these for a school.Apple's fix is to replace the lcd logicboard and the lcd cable.
Good luck

Most likely its a Hardware failure. To reaffirm... insert you install cd that came with your computer. restart computer and hold down "c" until you get the the install screen. Are you still getting vertical lines? You probably still are.. there can be 2 culprits. 1: logic board or video card. To figure it out which is it, hook an external monitor to it. If vertical lines then its the Logic board. If not then its the video card. Now for some odd reason the lines are not shown when you boot to cd, it may be an OS issue. another thing you can try. turn computer on and hold down Apple+option+P+R and let go after 3 chimes. ya never know. good luck!

You have a filter problem, check power supply for bad capacitors.