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    Dell N7110 backlit keyboard in an N5110

    Discussion in 'Dell' started by IMI4tth3w, Dec 23, 2015.

  1. IMI4tth3w

    IMI4tth3w Newbie

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    So i've been wanting a backlit keyboard for ages and google has told me this just isn't possible. Well i'm not ready to accept that. Plus this seems like a fun project to keep my busy this winter break while i'm out of class (studying Electrical Engineering)


    Looking at the N5110 motherboard, there are blank, unpopulated input tabs for the KBLIT1 spot.
    [​IMG]
    https://gyazo.com/59a82a115a046c0340c31d8a685fd293

    Looking at the N7110 backlit keyboard, the flat flex input that powers the backlit keyboard would line up perfectly. (the larger flat flex bends over on the n5110. it will fit). The keyboards are identical other than the back light capabilities.
    [​IMG]
    https://gyazo.com/1fe9dd595f7a0273997c8bd45ca8dc35


    Now some more google searching found the schematic for the backlit keyboard and the circuit components. This is from the Dell Inspiron N5110 Schematic pdf.
    [​IMG]

    Parts as follows:
    Component Location # | Part # | Description

    Components for the +5 volt line:
    F6901 FUSE-D5A6V-2-GP (0.5A 6V surface mount fuse)
    R6902 0R2J-2-GP (Resistor, not sure what value resistance)
    C6905 SCD1U10V2KX-5GP (1uF 10V surface mount capacitor)

    Components for the KB_LED_DET line:
    R6904 51KR2J-1-GP (51k surface mount resistor)
    R6903 100KR2J-1-GP (100K surface mount resistor)
    C6906 SCD1U10V2KX-5GP (1uF 10V surface mount capacitor)

    Components for the KB_BL_CTRL line:
    Q6901 P8503BMG-GP (N-Channel FET http://www.cheertech.com.tw/Niko-sem/Data sheet\P8503BMG.pdf)
    R6901 100KR2J-1-GP (100k surface mount resistor)

    Here's a picture where i circled each component and its associated location on the board
    [​IMG]


    Some things i'm worried about are the EC labeled parts. No clue what those are, and i don't see them mentioned in the datasheet schematic. EC4103 is already populated while EC9732 and EC9726 are unpopulated. Also R6902's resistance is a mystery.

    If anyone has any tips or clues about those parts, please feel free to chime in.

    I have an extra motherboard that my N5110 originally came with, as i swapped it with one that has discrete graphics. Will be using it to test this out and see what happens. Worse comes to worse i'll kill a motherboard i don't need. Best case, for those determined enough and willing to solder a few surface mount parts, will be able to finally get a back lit keyboard functioning on an N5110.
     
    IMI4tth3w, Dec 23, 2015
    #1