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T450 screen brightness - panel whitelist issue?

T430-T490, T530-T590 Series
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stumpie92
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T450 screen brightness - panel whitelist issue?

#1 Post by stumpie92 » Mon Feb 17, 2020 6:56 am

I bought a refurbished T450 running Windows 10 and I can't change the screen brightness. Could it be that I have a screen not in the BIOS whitelist [2]?
Lenovo thinks [1] my machine was built using a 1366*768 display, it was sold to me as having a 1600*900, and it actually has 1920*1080 (FHD).
The screen type (from HWInfo64) is N140HGE-EAA. The BIOS/EDID whitelist [3] I found includes N140BGE-EA3 and N140FGE-EA2 but nothing else matching closely.
I don't fancy hacking the EEPROM(s) [5], though I have contacts who could probably do it. I did read [4] that the latest Intel graphics driver for W10 (15.40) doesn't check the whitelist, but I've so far failed to install it.
So
  • do I have the non-whitelisted screen problem?
  • if I get the non-Lenovoised driver installed, will all be cured or will I have to use a third-party brightness app?
Your assistance is solicited! It has taken me some weeks to get to this tentative diagnosis, so I will be most grateful for any help.

[1] type 20BUS23J19 not in PSREF, support.lenovo.com recognises it s/n PC05H19X
[2]http://forum.notebookreview.com/threads ... ax.774101/
[3] lost the link!
[4]https://forums.intel.com/s/question/0D5 ... 0&tstart=0
[5]https://old.reddit.com/r/thinkpad/comme ... whitelist/
( 355 - 600E - 770 - X20 - T40 - T41 - T60 ) T410 - T450
(IBM indoctrinated) retirement addicted

BillMorrow
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Re: T450 screen brightness - panel whitelist issue?

#2 Post by BillMorrow » Thu Feb 27, 2020 7:13 pm

surely someone has something to contribute here..?
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She was not what you would call refined,
She was not what you would call unrefined,
She was the type of person who kept a parrot.
~~~Mark Twain~~~

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Re: T450 screen brightness - panel whitelist issue?

#3 Post by JPOESQ » Thu Feb 27, 2020 8:15 pm

(Deleted) - See posts below discussing whitelist.
Last edited by JPOESQ on Fri Feb 28, 2020 9:00 am, edited 1 time in total.
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Re: T450 screen brightness - panel whitelist issue?

#4 Post by RealBlackStuff » Fri Feb 28, 2020 2:33 am

Obviously OP has a non-approved LCD.
T450 et al still has that effing screen whitelist, but do not despair: Tutorial: T450/T450s/W550s/T550/X250 Screen Whitelist Removal
Or mod the EDID (see "more" below).
List of whitelisted screens and more found here: viewtopic.php?t=126671
Lovely day for a Guinness! (The Real Black Stuff)
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Re: T450 screen brightness - panel whitelist issue?

#5 Post by iamdmc » Fri Feb 28, 2020 7:53 am

Yep whitelist strikes again

It's the reason I'm hunting for a broken T450s (with screen intact) 1600x900 or 1920x1080

I only realised too late that my pop's T450 was 1366x768 :(
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stumpie92
Posts: 9
Joined: Sun Feb 16, 2020 11:23 am
Location: Colchester, England

Re: T450 screen brightness - panel whitelist issue?

#6 Post by stumpie92 » Fri Mar 06, 2020 8:48 am

Thanks those above who gave me the right pointers and perhaps courage to hack the BIOS.
I'd still like to know why I can't get the newer Intel driver to work - after all Linux doesn't look at the whitelist!
Bruce
( 355 - 600E - 770 - X20 - T40 - T41 - T60 ) T410 - T450
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stumpie92
Posts: 9
Joined: Sun Feb 16, 2020 11:23 am
Location: Colchester, England

Re: T450 screen brightness - panel whitelist issue?

#7 Post by stumpie92 » Sat Jun 20, 2020 11:57 am

Oh well, just flashed the BIOS and all went according to plan but the machine is I believe bricked. On pressing the power button nothing happens at all. I will open it up and see if there is something clearly broken as well as verify the BIOS image with /u/aracer03 on reddit.
I do have some novice-assisting tips for how to do it all, but that can wait!
( 355 - 600E - 770 - X20 - T40 - T41 - T60 ) T410 - T450
(IBM indoctrinated) retirement addicted

stumpie92
Posts: 9
Joined: Sun Feb 16, 2020 11:23 am
Location: Colchester, England

Re: T450 screen brightness - panel whitelist issue?

#8 Post by stumpie92 » Sun Jun 20, 2021 6:32 am

Returned to the fray! My T450 (modded BIOS) won't boot, but something happens. When I press to power up,every four seconds the power button, Fn, F1 and F4 key lights flash. Switch off works.
This doesn't always happen.
I have tried
1 - reset switch (via pinole)
2 - internal battery disconect, CMOS battery disconnect, CMOS reconnect, Internal reconnect
but neither of these makes any difference.
Any ideas?
( 355 - 600E - 770 - X20 - T40 - T41 - T60 ) T410 - T450
(IBM indoctrinated) retirement addicted

stumpie92
Posts: 9
Joined: Sun Feb 16, 2020 11:23 am
Location: Colchester, England

Re: T450 screen brightness - panel whitelist issue?

#9 Post by stumpie92 » Wed Jun 23, 2021 5:40 am

I have given up on removing the whitelist by modding the BIOS, so rewrote with the saved original version, and then read it to check for identity
Machine won't reboot though, even with AC power

On plugging in the power, red dot in logo flashed and white in power button flashed three times.

Tried starting, nothing happened, but then I get this: every four seconds the power button, Fn, F1 and F4 lights flashed. Switch off worked though, holding down the power button.

I have tried:
- system reset using paperclip - but I think this works only if machine is booted
- switch off then hold power button down for 30s, then switch on
- removing internal battery for 30s
- removing CMOS battery for 30s
- removing CMOS and internal batteries simultaneously for 30s
No luck in any of these cases.

Any further ideas? I feel sure it can be rebooted somehow and then at least I'm back where I started!
( 355 - 600E - 770 - X20 - T40 - T41 - T60 ) T410 - T450
(IBM indoctrinated) retirement addicted

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