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Daniel, Mac Genius
Category: Mac
Satisfied Customers: 4770
Experience:  Apple certified on desktop and portable, help desk qualified. Have owned and used Macs since 1989.
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computer turns on , fan is running , but no screen. makes the

This answer was rated:

computer turns on , fan is running , but no screen. makes the start up tone only.
Hello, my name is Dan.
I will do my best to help you, the only stupid question is the unasked one.

First suggestion.

  1. Shut down the computer.
  2. Unplug the computer's power cord.
  3. Wait fifteen seconds.
  4. Attach the computer's power cord.
  5. Wait five seconds, then press the power button to turn on the computer.

This might get it back, let me know. That is the first step.

Customer: replied 3 years ago.

ok tried it. no good. i have done this a few times. still no good

Ok Lou. This is a simple test to see if it is working but with no backlight for the screen
Take a flashlight and shine it sideways on the screen. Do this after powering it up of course.
Look very closely, if you see a faint image of the login screen or what you would normally see on startup then the backlight board needs replacement.
If you see nothing but a black screen then that usually means the screen has failed, the graphics card has failed.
Another test is to connect an external display, can be an HD TV or another monitor.
You will need an adaptor for this, depending on which model iMac you have it will use a Mini Display or a Thunderbolt to HDMI or VGA.

If you see what you should see then the iMac needs service for the screen or backlight.

That help?

Customer: replied 3 years ago.

ok. no image. so i will do the next test. if it is the grafix card or display what is a basic repair cost and is it something i can do without fancy equipment? i am very handy especially if it doesnt need software help


It is tricky but doable, you need to determine what it is and go from there.
This is where I go for disassembly and reassembly, they also sell parts.
Pick out the correct model and go for it, it does take some special tools.
Or I would take it to an Apple store, they can pin the issue down and they will quote a reasonable price to repair it.

I do it both ways depending on the problem, it may be worth the trip just for a second opinion.

That help?
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