Screen is not working (external display working)
I have an iMac that i do not know the full history of (brought from a sale sold as seen)
When i got the iMac home connected it powered up but it will not display anything
But when it is connected to an external display though mini display port i can get an image
diagnostic led 1,2,3 are on but 4 is off
my main questions are:
Can i test the display?
Is there away to fix it ?
Is it worth spending £100 on a screen?
Or is it simply the display data cable (from the display removal guide it seems common)?
I have checked all connections
(vertical sync cable,LED backlight power cable, display data cable, LCD thermal sensor)