Diagnostic LEDs

The iMac G5 has built-in diagnostic LEDs (shown in the following figure) on the main logic board that can help you to troubleshoot the computer.

1.
To access the diagnostic LEDs, begin by removing the back cover of the computer and grounding yourself as explained in Lesson 18, “Upgrading an iMac G5.”
2.
Locate the large white arrow in the middle of the board. Above this arrow, you'll see four LEDs.

  • LED 1 indicates that trickle voltage from the power supply has been detected. This LED will be on when the computer is turned off and the power supply is working correctly.

  • LED 2 indicates that the main logic board has detected proper ...

Get Apple Training Series: Desktop and Portable Systems, Second Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial