Apple MD094LL/A Manuale Utente

iMac (27-inch, Mid 2010) — General Troubleshooting 

2010-09-09

LED #1 = Power available.  

If no LED is visible:

•  Verify AC power source 
•  Verify known-good AC cable is connected
•  Verify cable connection between AC inlet and power supply
•  Verify cable connection between power supply and logic board
•  Verify power supply

LED #1 + LED #2 = Power available, and system is powered on. 

If second LED is not visible when power button is pressed:

•  Verify power button connection to logic board
•  Verify power button functionality
•  Verify cable connection between power supply and logic board
•  Verify power supply
•  Verify logic board

LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found. 

 If third LED is not visible after power on:

•  Verify that the MXM video card is seated properly
•  Verify if boot chime is present and fans are running when powered ON (reset SMC 

and PRAM, check backup battery if necessary for proper boot up):

•    

If POST boot chime is not heard, go to Won’t Start Up symptom flow,

•  • 

If POST boot chime is heard, go to No Video symptom flow.

LED #1 + LED #2 + LED #3 + LED #4 = Power available, system is powered on, video card 
found, and internal LCD found.

If fourth LED is not visible after power on:

•  Verify cable connections between LCD panel and logic board
•  Inspect LCD display cables for cable damage 
•  Verify external video functionality, and according to result check the following items:

         -If external display works then verify/replace the LED backlight board 
         -If external display works then verify/replace the LCD panel 
         -If external display does not work verify/replace the logic board