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iMac Intel 27" EMC 2309 (Late 2009, Core 2 Duo 3.06 or 3.33 GHz) ID iMac10,1, EMC 2374 (Late 2009, Core i5 2.66 GHz or Core i7 2.8 GHz) ID iMac11,1

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Problem booting up and getting to display



I have an iMac A1312 27 and the screen is totally BLACK not even glowing.

I already tried a




The only LED that doesn´t lit is LED 4.

If I put an external display everything is working 100% :)


I do believe that is something related to the INVERTER. but I tried a brand new one and nothing changed. Do you think that the cable from the POWER SUPPLY to the inverter could not be working properly?

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Soluzione Prescelta

I'd start by following Deep dive suggestions from Apple but would stop at #7

Deep Dive

1. Verify boot chime present and fans running when computer powered ON. (Reset SMC and clear PRAM if necessary for proper boot up.)

Yes Power on self test OK.

Go to step 2.

No Go to Won’t Start Up symptom flow.

2. Verify if image is visible on built-in LCD panel, with adjustable backlight level.

Yes Video present. Verify system functionality and return to user or go to appropriate troubleshooting flow.

No Go to step 3.

3. Connect supported external display. Verify if image appears on external display when system is booted.

Yes External display detected by system. Video circuitry on logic board functional.

Go to step 4.

No Go to No Video symptom flow.

4. Verify if LCD backlight is ON by looking for faint glow from display when viewed in darkened room with brightness set at maximum.

Yes LED backlight is functioning.

Go to step 7.

No Go to step 5.

5. Shine bright (low heat) flashlight onto front of LCD. With computer powered ON verify if a faint image is visible.

Yes LCD panel functional but backlight is missing or dim. Remove LCD panel and inspect and reseat the

following cable connections:

-Backlight power cable

between backlight board and LCD panel.

-Vertical sync cable between backlight board and LCD panel.

-DC power cable to backlight board and power supply.

Replace any damaged cable.

Reinstall LCD panel and go to step 6.

No No image or backlight.

Go to step 7.

6. Power ON system. Verify if image is now visible on LCD panel with correct backlight level.

Yes Issue resolved.

No Replace LED backlight board.

Retest. If issue persists, go to step 7.

7. Inspect and reseat internal DisplayPort cable (between logic board and LCD panel).

Power ON system. Verify if image is visible on built-in LCD display.

Yes Issue resolved.

No Replace internal DisplayPort cable.

If issue persists, replace LCD panel. Run Apple Service Display Utility to verify the resolution of intermittent display flickering symptoms. If the Apple Service Display Utility fails, contact Technical Service Provider Support

Anything after that, you'd have to measure some voltages on your logicboard.

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I already tested everything and IT IS the display connector on the logic board. Do you have a video/tutorial that shows how to REPLACE it?



@angelorecaman you did not say that you had already checked that. Anyhow this video shows how to replace the connector


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Try it with an external monitor. This model has issues with the GPU solder. Let us know your results.

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I already tried with an external monitor and it works 100%, so I guess it is some issue related to the LCD.


-Tested with a NEW LCD,

-Tested with a NEW INVERTER



What I am assuming is that something RELATED to the inverter is not working. Cause if was the LOGIC BOARD CONNECTOR the LCD should turn on and bright even in a glowing dark image. but it seems to be DEAD no energy at all.

Since I already tried a new INVERTER I am starting to think it is something related to the CABLES that bring energy to the INVERTER.

What do you think?



What do you think?

Actually I already TRIED new cables. Shouldn´t the LCD glow if the inverter is ok but the LOGIC BOARD connector is not?


Not if you have issues with your Panel power control circuitry.....


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Questa risposta era destinata originariamente a un'altra domanda.

I have the same 27 inch iMac 2009 model. I get a clean start up with chime and fans running but can not get a video image. not even with an external monitor. I know the power supply is good, the backlight board is good and the video card is good as well. Any ideas anyone?

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was this resolved? I have same machine and same symptoms with new HD. I am going to replace the Vsync ribbon, but would like to verify if the video card is loose. Do you know where it is?


on a 27 inch iMac 2009 i7 I had the same problem, it was due to the temperature sensor of the LCD panel. Apple uses a 2N3904 transistor as a standard component which is easy to get in electronics stores for 1-2 €. Pay attention to how it is soldered.

I came to this through the tool HWSensors, which displays the measured values of all (?) Temperature sensors, for the LCD sensor it showed over 130 ° C, which could not be correct.


Interesting, im going to have to try this on my 2011


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Angelo Recaman sarà eternamente grato.
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