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

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iMac Black Screen, Startup Chime Audible But No Display

So I had this problem around a month ago. I started up my iMac to hear the startup chime, but the screen was black. I assumed it was a graphics card issue, but before I replaced the graphics card I bought a Mini-Display to HDMI adapter and no display once again. I then replaced the graphics card and nothing changed. What could be the issue? I checked over the cables a few times and they are all connected and they are tight into the sockets. Any help?

EDIT: These pics are of the LCD Cable that I believe is broken and the socket [which I hope isn’t damaged because I can’t solder to save my life.]

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What do you see if you place a flashlight on the screen? Do you see the faint image of your desktop and its icons?

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I tried with my iPhone flashlight and I couldn't see anything.

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LED 1&2 on, 3&4 off. No latent backlight on screen. Ordered a new display to motherboard cable. LVDS will see later

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You’ll need to take the display off so you can see the onboard diagnostic LED’s. Follow this IFIXIT guide: iMac Intel 21.5" EMC 2389 Display Replacement

Here’s the location of the LED’s

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And here's a breakdown of the onboard diagnostic LED's:

  • 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.

Let us know what you find

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With the LCD Screen removed, Light 1 and Light 2 were green when the machine was turned on. Light 3 was not on with the LCD disconnected. I went to reconnect the LCD only to find that the fragile gold ribbon cable had bent pins on it. I believe I broke that cable during today's repair and this could be the issue.

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Yes, that sounds like what happened. You'll need a new cable and you'll want to inspect the socket as well. Often time I find the connector is also damaged so the connections are not making contact.

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I think the socket looks fine, but I'm not really sure what I'm looking for. Nothing seems to be chipped or bent.

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Take some pics of both the cable ends (top & bottom) and the logic board socket from all five directions so I can see what you have. Need sharp well lit pics of the connector alone Adding images to an existing question

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Added photos of the cable, still working on getting good lighting for the socket pictures.

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I have all 4 diagnostic lights on but still have a black screen (with back light on) Any ideas?

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My guess is that you had (and still have) a GPU card issue (it is common in these machines), and you also need a video cable as one end of this is trashed. You ll have to inspect the connector also to see if there is some piece of the ruined cable there. If not then there is a good chance that the connector is good

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Take a flashlight hold it against the screen at a sharp angle do you see your desktop icons? If you do then the backlight cicuilt has an issue.

It would be best to give us more details on what is your exact model as well as the systems history.

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mine, it’s the socket, it keeps disconnecting. what can i do to prevent this?

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update. now all of the bulbs are on but nothing

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In my case my iMac will chime after pressing the power button then LED 1, 2, 3 are ON but LED 4 is OFF and the LCD display is completely dark. I’ve tried shining a flashlight onto the surface and there is nothing visible. If I connect the iMac to an external display, I can use the computer normally as it’s generating a video signal and everything is functional except the internal display.

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I have a 21/5" i5 2.9 late 2013. iMac14,3 unit. LEDs 1, 2, 3 on and 4 off. The SSD is running a clean copy of Catalina and works fine. I replaced the LDVS cable with a new one. Get Black screen (no latent image) but no video (obviously) the fan seems to be running, but not at top speed. The Display was working well, but customer reported some video problems on screen. My thought is it is the video out of the motherboard (no Vid card on this?) which means a new motherboard? Any assistance is helpful. I am putting this one aside for now. I have successfully done SSD upgrades to 5 of these so far this month, no problems. Any help is appreciated. Will see if my part vendor has a board. If there was a video problem, could be the driver/ ? in the display. Not good. HELP!

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carl again, the iMac is EMC 2042 and A1418. most data is in my above comment. Thanks. Carl

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