Model A1311 / Late 2009 / 3.06 or 3.33 GHz Core 2 Duo processor

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LCD Screen will not turn on

To start with, I was handed an iMac that "won't boot" and I'm trying to fix it. This is the first time I have ever tried to fix a Mac, but figured it would be worth the effort to start learning about them.

I thought at first it was a power supply issue, because I didn't see any lights flashing and the screen didn't turn on when I pressed the power button.

I did some research, and found enough information to be able to remove the glass, and LCD screen to look for some LED indicators. I never found the LED indicators but I accidentally hit the power button on the device, and the fans started spinning. So I'm fairly confident it's NOT the PS.

So I went and hooked everything back up the way it was supposed to be, hoping maybe something just shook loose somehow, and same thing happens.

When I press the power button, I still hear 2 fans start up, but I never hear a beep, and I never see any LED lights come on. The LCD screen also doesn't "lighten up" when the back light initially powers up, so I'm not sure what the issue is.

My initial thoughts are video card and/or LCD screen is bad.

Again, I'm new to fixing Mac's so let me know if you need any other information from me.

[EDIT 10-16-11: figured out it's an Intel iMac 21.5" (Late 2009)]

[EDIT 10-22-11]

Replaced Power Supply and still same issue happening. I'm going to try and hook up an external monitor and see if that's going to show an image.

Would it be possible that the LED driver board went out? Is there a way to test for it? Is there anywhere that I can buy a new LED driver board?

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The diagnostic LEDS should be to the left of the RAM slot. Remove the frame so you can see them. Sometimes they have a piece of black electrical tape covering them, remove it and let us know what your results are on start up.

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How do you remove the frame of the iMac?

I removed the "door" to where the memory is installed. There are 2 used slots (of 4 available), but i do not see any location for LED or any type of indicator.

I looked on this website, and didn't see a guide that I thought would help me remove the frame.

Thanks for the response.


Never mind the frame, I was thinking of another machine. But the LEDs should be just under the screen, so just lift it up some to be able to see them.


Ok, I have the glass screen off, and the LCD panel off as well. If I have the iMac facing me like I was going to working on it, I can see 1 faint green light on towards the right side of the memory slots.

However, I can't tell how many other LED's there are, and which one of the 4 is lit up. Any ideas?


I've only see the LEDs light in order. With just one, I would replace the power supply.


I saw a comment in another post about a piece of tape that could be getting in the way of seeing the properly.

That was my issue, and now I clearly see all 4 LED indicators.

As I'm looking down at them, I see the following:


So I see 3 LED's, a space, and a single LED

The LED on the far left is the only LED lit up when I plug in the power cord. To me, this is LED 1.

When I press the power button, LED 1 and LED 2 light up. After a few seconds there is a "click" (for lack of a better word) and LED 2 turns off.

This process repeats itself until I press and hold the power button for 5+ seconds.


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iMac de 21.5"de pantalla Negro

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