Model A1311 / Mid 2010 / 3.06 & 3.2 GHz Core i3 or 3.6 GHz Core i5 Processor

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Just recieved broken iMac. Only led 1 and 2 on.

I just bought a used imac 21.5 emc 2389

Was told power supply was replaced but its still not working. (Have reciept and old power supply so i know it was replaced)

So with some help from google i checked the led diagnostic lights and light 1 and 2 light up but 3 and 4 do not.

I get no chimes, no beeps, screen does not light up or do anything.

This did not come with a keyboard or mouse so i will have to buy them IF i can get it to boot up.

From my googling ive found that led light 3 not lighting up means that the logic board isnt recieving signal from the graphics card?

Is there ANY other things to check befoe ruling its the graphic card or logic board?

Would like to get this working as cheap as possible.

Thanks in advanced

Answered! View the answer I have this problem too

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Just took it all the way back down to the logic board again. Pulled gpu, Reseated it. Checked power supply cable pins-Checked out good.

Made quadruple positive all the wires are hooked up and hooked up correctly.

Put it all back together and same thing-power cord plugged in 1st led diagnostic light on.

Hit power switch, Fans and hdd turn on, 1st led remains on. 2,3,4 are off.

After a few seconds fans increase to full speed, with only the 1st led on.

Nothing changes after that.

Ive unplugged and rebooted a few times with the same results every time.

I even switched out the brand new power supply in it for the old one and got the same results (Looks like the old one was still good (got proper 12v and 5v readings from it)

I am at a loss as to what happened.

Did I kill the gpu chip which fried logic board?

Did I mishandle something?

Missing some small hidden cable?

I did something wrong but have no idea what.


Any suggestions?


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LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

I'd pull the video card and reflow it with a hot air rework gun. You can go low dollar on it with something like this:

Here's how to get to it:

iMac Intel 21.5" EMC 2389 GPU Card Replacement

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Thanks for the super fast response.

What is a hot air rework gun?

Are you fairly certain the graphics card is at fault?

Id prefer not to tear the entire thing down to get to it but If there is a good chance that it'll fix my problem, I will give it a go!


I gave you a link to the hot air gun, click on it. Am I certain, about 95%. You don't I'd answer this if I hadn't done the repair several times do yo?


Whoops didnt see the link to the air gun before.

I just watched a youtube video of someone repairing one of these with a butane torch. Would this also work?

If so Id only have to get new thermal paste and pads. (Id have to order them online so I wont be able to attempt a repair until I receive them.


I wouldn't attempt it with a torch. You need about 450 degrees and you have to watch it and move the gun until you see it flow. You can always resell the unit and only loose about $10-15


@mayer I found a better reflowing pencil, also is variable for air and heat.


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