Dell OPTIPLEX 990 Service Manual download pdf (Page 68)

Troubleshooting

Diagnostic LEDs

NOTE: The diagnostic LEDs only serve as an indicator of the progress through the

Power-on Self-Test (POST) process. These LEDs do not indicate the problem that

caused the POST routine to stop.

The diagnostic LEDs are located on the front of the chassis next to the power

button. These diagnostic LEDs are only active and visible during the POST

process. Once the operating system starts to load, they turn off and are no

longer visible.

The system now includes pre-POST and POST LEDs in an attempt to help

identifying a possible problem with the system easier and more accurate.

NOTE: The diagnostic lights will blink when the power button is amber or off, and

will not blink when it is blue. This has no other significance.

Diagnostic Light Patterns

LED

Power Button

Problem

Description

The computer is either turned off or is not receiving power.

Troubleshooting

Steps

• Re-seat the power cable in the power connector at the

back of the computer and the electrical outlet.

• Bypass power strips, power extension cables, and

other power protection devices to verify that the

computer turns on properly.

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Dell OPTIPLEX 990 Service Manual Page 68