Display won't come up - iMac works perfectly on secondary screen

[007 Junior]

Hello everyone,

I've got a Mid 2007 20" iMac since yesterday for a very nice price. The only problem with this iMac is that the display won't come up. The Mac works perfectly and flawless on a secondary screen though.

Yesterday I've did a clean install of OS X Yosemite with all updates, I've repaired all disk permissions and ran the Apple Hardware Test on the machine. The AHT didn't find any hardware problems in the machine.

I've also shined a flashlight on the screen. Top to bottom, bottom to top, sideways. Unfortunately, without any results. So now I've come to the conclusion that there 3 parts that may need to be replaced.

1. LCD-display
2. LVDS cable
3. Inverter board

Which hardware do you guys think this problem could be related to??

 

[007 Junior]

So, I've made some progress today! After opening up the iMac, it immediately became clear that the LVDS cable wasn't even connected to the logic board! No wonder the screen remained black.

Unfortunately, reconnecting it DID NOT solve the problem. When I boot up the iMac now, all 4 LED's on the logic board turn green and the display itself lit up and that's it. No Apple logo, no spinning wheel, nothing. Just a bright and empty white screen. It DOES boot however on my secondary screen. And the brightness of the build-in LCD is noticeably adjustable.

I do think the LVDS cable needs replacement, but I'm not quite sure.
Can anyone confirm, please?

 

[007 Junior]

Guess I have found my confirmation already!
http://www.powerbookmedic.com/wordpress/2009/07/31/diagnose-your-lcd-problem

The third issue is just a solid white or gray screen. If the machine still boots up, but there is no picture, this means your backlight is working fine, but there is something wrong getting the picture up to the LCD. This in most cases is going to be a damaged or disconnected display (LVDS) cable. It may have just come loose from the back of the LCD or from the main logic board or it got damaged somewhere most likely in the hinge.

Just ordered a new cable and will report back when I replaced it!

 

[007 Junior]

So I replaced the LVDS cable and my LCD is still not showing any video. Still a solid white screen. I'm afraid the next step is replacing the whole LCD-panel, but before I do that I would like to hear thoughts of you guys about this.

Please let me know!