HP 18XL381 manual Backlight brightness cannot be adjusted with Fn+F7 or Fn+F8

Presario 1800/1800T Series

Models: XL280, XL380, XL381,

and XL390

	Display
Problem	Probable Cause	Solution(s)

Backlight (brightness) cannot be adjusted with Fn+F7 or Fn+F8.

This display panel has a continuous pattern across it (e.g., “jailbars” pattern), has a single color on it, or has garbled graphics across the entire panel. This failure is for patterns across the entire panel (not just on one section).

A single line, small group of lines, or block appears on the display panel. This failure occurs in only a section of the display panel.

Improper display cable connections.

Defective inverter board.

Defective display cable.

Defective system board.

Improper display cable connections.

Defective display cable.

Defective inverter board.

Defective system board.

Defective display panel.

1.Reseat the display cable to the system board.

2.Replace the display assembly.

Replace the display assembly.

Replace the display assembly.

Replace the system board.

Reseat the display cable to the following until the problem is solved:

1.System board

2.Display assembly

Replace the display assembly.

Replace the display assembly.

Replace the system board.

Replace the display assembly.

Note: When you perform a “self-test” on an external VGA color or monochrome monitor, the screen should be white. A narrow black border may also appear on the left and right sides of the display. Either of these displays indicates that the monitor is working properly.

PRESARIO NOTEBOOK MAINTENANCE AND SERVICE GUIDE 1800 SERIES TROUBLESHOOTING 25