"Compaq.com - Compaq Presario Series Maintenance and Service Guide - Models: 1683, 1685, 1687, 1688, and 1690
Display is blank and the Suspend icon is flashing.
Internal display is blank and the screen on an external monitor displays information.
Display has overheated. 
System is in Suspend mode.
Display function was switched to the external monitor.
If computer is in direct sunlight, move it and allow it to cool off.
Press any key or touch the Touch Pad.
Use Fn + F2 to switch between LCD or CRT.
Problem
Internal display flashes or has garbled characters when computer is connected to external monitor.
Probable Cause |
| Solution(s) |
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Using 1024 x 768 or higher |
| Restart the computer. |
resolution on external |
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monitor and have toggled |
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back to internal display, |
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which supports up to |
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800 x 600. |
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The light tubes on the edge of the display panel do not light up at all and
The light tubes on the edge of the display panel do not light up at all and
Improper backlight or |
| Replace the display assembly. |
display cable connections |
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Defective inverter board. |
| Replace the display assembly. |
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Defective display cable. |
| Replace the display assembly. |
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Defective display panel. |
| Replace the display assembly. |
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Defective system board. |
| Replace the system board. |
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Defective system board. |
| Replace the system board. |
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Backlight (brightness) cannot be adjusted |
| Improper display cable |
| 1. | Reseat the display cable to the |
with Fn + F7 (¯ ) or |
| connections. |
| system board. | |
Fn + F8 (- ).*** |
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| 2. | Replace the display assembly. |
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| Defective inverter board. |
| Replace the display assembly. | |
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| Defective display cable. |
| Replace the display assembly. | |
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| Defective system board. |
| Replace the system board. | |
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Contrast cannot be adjusted with |
| Improper display cable |
| 1. | Reseat the display cable to the |
Fn + F5 (¯ ) or Fn + F6 (- ). |
| connections. |
| system board. | |
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| 2. | Replace the display assembly. |
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| Defective inverter board. |
| Replace the display assembly. | |
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| Defective display cable. |
| Replace the display assembly. | |
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| Defective system board. |
| Replace the system board. | |
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**This problem indicates that the backlight or its power circuitry has failed. Since you cannot observe the POST result on the display panel when the backlight is not functioning, connect the unit to an external monitor before powering the unit up. If an external monitor is not available, verify that POST completes by opening and closing the display, listening for the single or double beep, and watching for the LEDs turn on at the front of the computer.
file:///C/SERVICE%20MANUALS/COMPAQ%20_%20chec...01685%201687%201688%201690%201694/solving.html (5 of 8)6/27/2004 2:57:51 AM