replaced my screen now its dim help plz :( , help fix edid

Discussion in '2015+ Alienware 13 / 15 / 17' started by ashknani, Jul 30, 2017.

  1. ashknani

    ashknani Notebook Consultant

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    Ur probably right.
  2. t456

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

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    Had some pm's back-and-forth with @ashknani and nothing software-wise seemed to make any difference.

    There is one hardware mod that is guaranteed to work; snipping the PWM wire on the display cable (this one being responsible for brightness control). On most displays these work on a voltage=off basis, so disconnecting it entirely will ensure 100% brightness, regardless of any software setting. Tested just now on my 4-lane eDP display and this worked as expected:


    It isn't very hard to do, requiring only pliers or scissors and some tape. Sleep-mode, closing the lid and other backlight-off's will still work since this mod will only affect the dim signal, not the 'backlight-fully-off'. The process is also reversible by simply soldering the wire ends back together.

    1.) First locate the appropriate pin and its wire. On a 30-pin eDP it's #23 and on a 40-pin (such as the OP's B173HAN01.1) it's #33:

    LQ133T1JW02 - 40-pin, 4-lane eDP cable, wrapper

    2.) Peel back the wrapper, clip the pwm wire and wrap the ends with a piece of tape (just in case, to prevent shorts):

    LQ133T1JW02 - 40-pin, 4-lane eDP cable, pwm-wire cut

    Done; 100% brightness.

    However, if the situation is not low-brightness (10%), but actually no-backlight-at-all then it needs a different mod. No-backlight means you need to shine a flashlight on the screen to see anything on the display, if it's just barely visible then it's the pwm-snip you want.

    1.) Take a small piece of thin wire and short backlight-on/off with either Vdd (control voltage) or ground (control ground):

    LQ133T1JW02 - 40-pin, 4-lane eDP cable, short vdd (or gnd) and bl-on

    Actually guessed wrong here, btw :vbbiggrin: . Had to short it to 23-26/ground instead; this mod resulted in backlight permanent off. Anyway, swapping the wire resulted in full-on, but the disadvantage with this mod is that nothing will ever turn off the backlight, meaning continuous power draw even in sleep-mode or closed lid (~80% of the lcd's consumption is due to the backlight). Mind also that soldering 0.4mm pitch is finicky business, so wouldn't try this without a magnifier and small-tipped soldering iron. A shop might be better suited if you don't happen to have such tools.

    Flashing an edid to a modern eDP panel requires hardware tools since the panel's eeprom is likely write-protected. If that were also true on the bricked LVDS displays then they'd never have bricked in the first place. Could still flash a white-listed edid on this B173HAN01.1, but then you'd need a programmer and probably jumping the wp-pin on the eeprom. Also very risky business since you chance to corrupt the non-edid part of the firmware even by merely reading out the eeprom :oops: (fixed it, fortunately ...). Might still attempt this, of course, but do be careful then.

    An edid tracked down by @ashknani will probably work fine for an edid-flash; it's from a B156HTN05.x, equally a 15.6"+120Hz+1080p+Dell (physical size is irrelevant). Only question is how the system will handle positive vs. negative sync polarity ... it might offset the screen a bit, yet is otherwise harmless to try:
    edids AUO51ED and AUO119D.7z

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