As this issue about your iMac or MacBook Pro/Air going black screen can occur for a variety of reasons, first of all, you should find out the probable cause to resolve the issue much easier. Before starting the procedure of solving the problem, it is a good idea to make note of some important considerations. If the issue persists with known-good SDRAM, replace the logic board.Top 7 Effectual Ways to Fix A Black Screen on iMac or MacBook Pro/Airĭid you encounter the Mac displaying a frozen black screen unexpectedly and for no apparent reason? What should you do? It's exactly the kind of problem that brings things grinding to a halt while being frustratingly unpredictable. Replace the SDRAM with known-good memory and test. No: The logic board is not passing the Power-On Self Test (POST). See “Troubleshooting No Video” in this chapter. Yes: The power systems of the computer are working correctly. At this point in the Power On process, you should hear a boot chime and see that LED #1 and #2 are On. LED # 2 comes on momentarily or stays Off: Replace the Power Supply.ĩ. LED # 2 is On: The Power Supply is functioning. Check to see if LED # 2 comes On, comes on momentarily, or stays Off. If the issue persists, replace the AC line filter.Ĩ. If both the AC outlet and the power cord are good, replace the AC/DC power supply. LED #1 is Off: This indicates that the computer is not detecting AC power. LED #1 is On: This indicates that the power supply is getting good power from the AC outlet. Plug the power cord into the iMac and the power cord into the AC outlet. See “Diagnostic LEDs” in the General Information chapter for complete instructions on this procedure.ħ. Remove the memory access door and front bezel to gain access to the four diagnostic LEDs. Remove and reinstall the SO-DIMM memory modules, located in the bottom of the computer. Follow instructions in the General Information chapter to reset the SMC. Yes: You may have a loose fit to your power cord. Verify that the power cord is securely plugged into both the AC outlet and back of the computer. Check the connection of the power cord on both ends. Plug a different device into the socket to ensure there is power, or plug the iMac into another outlet. The Display Remains Black and There Are No Sounds From the Fans or Drives.ġ. 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.
Indicates that the computer and the LCD display panel are communicating. 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. when the computer is communicating properly with the video card.Indicates that the computer and the video card are communicating. This LED will be ON when the computer is turned on and the power supply is working correctly. Indicates that the main logic board has detected proper power from the power supply when The LED will turn off only if the AC power source is disconnected or the power supply is faulty. The LED will remain on even when the computer has been shut down or put to sleep. This LED will remain ON whenever the iMac is connected to a working AC power source. Indicates that the trickle voltage from the power supply has been detected by the main
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