Laptop & Desktop - No backlight diagnostic steps

Laptop & Desktop - No backlight diagnostic steps

Problem

A customer laptop is not showing display when powered on, the screen appears to be black but power or hard disk lights show on the laptop as hey normally should.


Applies to

  1. Any Windows laptop

Resolution

Problems with no backlight is common on most laptops with LCD and backlight to drive the screen.  Due to  the relatively high voltages used to drive the backlight component failure can result in the power to the backlight.  However it is possible that other factors could also cause the screen to go dark that do not require the unit to be sent away for repair. 
  1. Check if during power up the display panel lights up for the manufacturer logo (even briefly).
  2. With unit powered on shine some bright light at the screen, it may be possible to discern is the LCD panel part is still working even if backlight has been dimmed or not working.
  3. Try increasing brightness using function row hotkeys if available.
  4. Connected to external monitor or TV then try toggling external monitor using function row hotkeys if available.
If diagnosis is unclear after working through the above points and you can hook up to external monitor or TV use the steps below the rule out  problem with settings or driver when Windows runs normally.

  1. Connect laptop to external monitor and start up the laptop.
  2. Open the Windows Start menu.
  3. Click the Power icon.
  4. Hold down the "Shift" key.
  5. Click "Restart" as you continue holding down Shift.
  6. Release the Shift key when you see a blue screen.
  7. Open the Troubleshoot menu.
  8. View your advanced options.
  9. Access the command prompt.
  10. Then repeat the tests using the function row hotkeys for brightness and external monitor toggle.

If panel does not light up then the problem is most likely to be a non-functional display backlight.


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