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    Screen back light goes off when plugged in

    Discussion in 'Hardware Components and Aftermarket Upgrades' started by Hari1989, Jan 21, 2015.

  1. Hari1989

    Hari1989 Newbie

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    Hi, I have lenovo think pad e420 laptop 3 years old (no warrenty).

    It has very strange problem. When i connect power cable to laptop, the screen backlight goes off, when i remove the power cord and run it on battery the screen backlight will work properly.
    Very difficult to run my laptop for me.
    I have installed all latest power management software, tried all tricks in the book. i think it is a hardware problem, but I dunno what to change.
    I have changed refresh rate of laptop, installed latest graphic drivers etc, even the LCD cable is fine. Still problem persists, I use this laptop for hours connected to external monitor

    Some one please help me resolve this issue, :confused:

    Thanking you,
    Hari :thumbsup:
     
    Hari1989, Jan 21, 2015
    #1
  2. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    Do you see this problem when you boot into the BIOS? If you do then first check the various power and backlight options in the BIOS. If the backlight behaves correctly when in the BIOS then the problem lies with some confused setting in the Windows power management.

    John
     
    John Ratsey, Jan 21, 2015
    #2
    tijo likes this.
  3. tilleroftheearth

    tilleroftheearth Wisdom listens quietly...

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    Good point John. If the issue indicates that Windows is the possible issue, try creating a new Power Profile with default settings and see if that fixes it.
     
    tilleroftheearth, Jan 21, 2015
    #3
  4. ajkula66

    ajkula66 Courage and Consequence

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    I would tend to believe the same thing. Hopefully we're both wrong.

    What happens if you remove the battery and run the laptop on AC only?
     
    ajkula66, Jan 21, 2015
    #4
  5. Hari1989

    Hari1989 Newbie

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    Thanks Guys for your reply.

    I have tried running it on BIOS, backlight sill doesn't work, if I run BIOS on Battery, then everything is ok.
    If I remove battery and just run it on AC then still the problem exits, I`m sure it not software, but dunno what hardware to change, the mother board or the DC sub Card. I even have a new charger/adapter.

    Thanking you,
    Hari
     
    Hari1989, Jan 21, 2015
    #5
  6. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    You could try reinstalling the latest BIOS and also using any reset option in the BIOS (are there options for backlight brightness?). It's unlikely that this will fix the problem but it's worth doing before tackling the hardware.

    John
     
    John Ratsey, Jan 22, 2015
    #6
  7. Hari1989

    Hari1989 Newbie

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    Thanks John, but I`ve tried updating BIOS, but now i`m sure its hardware problem, I dunno which component to change, DC-sub Card or Motherboard
     
    Hari1989, Jan 22, 2015
    #7
  8. ajkula66

    ajkula66 Courage and Consequence

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    Motherboard would be the main suspect in my opinion...

    Good luck.
     
    ajkula66, Jan 22, 2015
    #8
  9. Tinted

    Tinted Notebook Enthusiast

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    i know this is silly , but try increasing brightness after connecting the wire
     
    Tinted, Jan 22, 2015
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  10. Hari1989

    Hari1989 Newbie

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    All that doesn't work Tinted
     
    Hari1989, Jan 23, 2015
    #10