w550s/t550 LCD screen replacement - brightness set at max.

Discussion in 'Lenovo' started by giggidy, Apr 5, 2015.

  1. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

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    After you've written the whitelisted edid to the panel it doesn't matter which bios version you flash; they all contain the whitelist (otherwise existing customers would complain). The only exception is downflashing to v1.19 or earlier since these versions lack the LP140WF6-SPB2 and LTN140HL05-901 edids. So ...better flash the SPB1 then, just in case you want to go way back.

    And do read the readme.txt before assuming flashing the latest bios is good merely because it's the latest. Dell and HP, for one, tend to pull this dirty trick:

    initial bios -> +1 month -> v1.1 -> +1 month > ... -> +2 months -> v2.3 -> ~3+ years -> v2.4

    Thing is that that v2.4 will have no bugfixes or improvements, except for one that's only beneficial to the manufacturer; it will flip the bios eeproms bits to protected and ensure no further flashes are possible, whether that concerns older, newer or modified bioses. Even an identical version will not work, which would also prevent you from fixing a corrupted bios. A scenario like that can happen even without having a bad flash, either due to bugs in the bios, a virus or some poorly formatted piece of software or driver with low-level access.
     
  2. mtlfact

    mtlfact Notebook Enthusiast

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    I modified the bios itself using a chip read/writer. Based on what you said I should just disregard the 1.26 t450 bios upgrade? The release log:

    CHANGES IN THIS RELEASE
    Version 1.26

    [Important updates]
    Nothing.

    [New functions or enhancements]
    - Security issue update.
    - Updated the Diagnostics module to version 2.09.09.

    [Problem fixes]
    - Fixed system may hang windows splash logo after update BIOS v1.25.
     
  3. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

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    If you use a programmer then it doesn't matter; flash away. But then, as you've guessed, you'd have to redo the modification since the stock v1.26 will not have the customized whitelist.
     
  4. mtlfact

    mtlfact Notebook Enthusiast

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    I'm looking to install a non lenovo wwan card in my t450. Any idea how I can remove whitelist from bios?
     
  5. DodoBenz

    DodoBenz Newbie

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    There isn't any whitelist anymore. Replaced my Intel card with a Broadcom with and worked straight in
     
  6. mtlfact

    mtlfact Notebook Enthusiast

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    Oh really. That's great news. Thanks!


    Sent from my iPhone using Tapatalk
     
  7. Tolife

    Tolife Newbie

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    I'm trying to find the pin-outs for my LCD so that I can write the white-listed lenovo edid to the eeprom.

    The display i've bought is the B140HAN01.3. It is an original model from the factory.

    Here is a picture from the front PCB:
    [​IMG]
    And the back:
    [​IMG]
    Largerly inspired by @KnielsenDK , I have found following pin-outs:
    1. MSDA
    2. MSCL
    3. EP_WP
    4. GND (I'll just connect GND to one of the outer screws.)

    I have not yet found the VCC Pin. :((

    Does anybody with experience know where to connect the VCC?
     
  8. arvest

    arvest Notebook Enthusiast

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    Try to google the name on the EEPROM chipset, that might give you the datasheet, and with that the pinout of the chip.

    Also, SCL and SDA are pulled high with a (probably) 4.7 or 2.8kohm resistor. So try to find this resistor, it should connect to Vcc.

    A little more dangerous method is to attach the display to the laptop and power it on. Then probe each pin with a multimeter until you find the one(s) at 1.8 or 2.5 or 3.3 volts (whatever the voltage it is driven with). If there is only one, it is the Vcc pin. There are also some address pins on there that might be high, so this doesnt gove you a straight answer.
     
  9. mtlfact

    mtlfact Notebook Enthusiast

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    Why not flash the bios? I think it's easier and less risk of damaging anything.


    Sent from my SM-N920W8 using Tapatalk
     
  10. Tolife

    Tolife Newbie

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    Flashing the right edid is my first choice.
    Id rather brick my screen than my laptop.

    Besides, changing the edid is more surgical (less invasive) and more permanent (upgrading the bios will be easier)
     
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