Solution for Black Screen for iMac

Try turning the Brightness down low and see if it stays on and doesn't go completely black. If so then you have the same problem I have on my 2010 iMac 27", which I have so far not been able to find a good solution for. I have replace power supply and video inverter card, and still have this problem.

It is almost certainly a hardware failure, if you cannot see any video but can hear sounds (including just the fans) then it is likely either the display backlight or the display itself. Whichever it is it is nothing something a user can repair, please make an appointment at your local Apple Authorized Service Provider to have the computer assessed and then you can decide on your course of action.

If you have 1/2 way decent credit you can get 18 months same as cash using Barclay bank. I always use that, why use my own money when I can use Barclays? i just set an auto payment of whatever the balance is divided by 18.

For example: $2500/18 = $138.88. Set up the autopayment and 18 months late you have been enjoying your Mac for 18 months. Its easier to live without $138.88 for 18 months rather than save up $2500 that you can spare. Its just very simple and basic money management.

Obviously your choice, I'm trying to help you by suggesting something you may not have known about or considered.

At what point dies the screen go black?

Do you mean it is always black, or goes to black at points?

Use a Flashlight up close at various angles, do you see a faint Desktop?

Does that mean you see a faint Desktop with a flashlight?

Uh... its a 2010 iMac. Apple Service doesn't care about it. And any local "authorized" provider aren't interested either. They would rather you buy a new one.

Considering its 11 model years old, perhaps that is exactly what you should do, buy a new one.

When I get a spare $2500, that's probably what I'll consider.