Chosen Solution
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.]
SOCKET:
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
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
I have all 4 diagnostic lights on but still have a black screen (with back light on) Any ideas?
mine, it’s the socket, it keeps disconnecting. what can i do to prevent this?
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.
