iMac G5 (20-inch iSight) Troubleshooting — General Info 144
The four labelled diagnostic LEDs shown below. 14.
LED 1: • Indicates that trickle voltage from the AC power inlet to the power supply has
been detected. This LED will be ON when the computer is turned o and your power
supply is working correctly.
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 main logic board has established communication with the LCD
display.
LED 4: • Indicates a processor over-temperature condition. The system will shut down
when this LED turns on.