cancel
Showing results for 
Search instead for 
Did you mean: 
Reply
drdtyc
Paper Tape
Posts: 8
Registered: ‎10-02-2015
Location: Canada
Views: 787
Message 1 of 7

T420 LCD brightness problem after upgrade to 1600x900 HD+

I have upgraded the LCD of my T420 from a 1366x768 HD panel to a 1600x900 HD+ panel and changed the LCD cable from an HD cable to an HD+ cable.

Everything runs fine with the enhanced screen resolution, except one problem.

The Fn+Home (increase brightness) and Fn+End (decrease brightness) hot keys are not working properly.

I have to press Fn+Home to the full brightness (15) to use the laptop. Anything less than full brightness (1 to 14) gives me a completely dark screen i.e. a blank screen showing nothing as if the laptop was switched off.

I have upgraded the BIOS, the graphic driver (Intel HD driver) and the Hotkey integration utility. But this brightness problem still persists - i.e. only full brightness works or a dark screen with anything less than full brightness.

Any suggestion is welcome.

Community SeniorMod
Community SeniorMod
Posts: 11,853
Registered: ‎06-06-2011
Location: RU
Views: 780
Message 2 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

Hi

Is the graphics driver from Lenovo site?



x220 • Gobi 2000 3g | hdd, msata ssd, wwan, wifi, gps -- unique hand-made config
ThinkPad 25 Special Anniversary Edition. #retro. Signed by D.Hill
T470p | X1 Carbon Gen3 | Miix 2 10" | Yoga Tablet 2-1050F (Android) + BT Keyboard
ThinkPad Stack • 2.4/5 Wireless Router, HDD 1 TB, BT Speaker, Power Bank, Mobile Projector

Do it well, worse becomes itself

Communities:   English    Deutsche    Español    Portugues    Русскоязычное    Česká    Slovenská    Українська   Moto English

drdtyc
Paper Tape
Posts: 8
Registered: ‎10-02-2015
Location: Canada
Views: 771
Message 3 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

Yes, the drivers are from Lenovo support page.

Community SeniorMod
Community SeniorMod
Posts: 11,853
Registered: ‎06-06-2011
Location: RU
Views: 764
Message 4 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

It looks strange enough. I know about such behavior (brightness levels) with Intel's native drivers for HD 3000. But not Lenovo's ones.

Could you remove Lenovo Power Management driver, Intel HD 3000 drivers, Hotkey package and reinstall them in the order above? Or, better, use ThinkVantage System Update and allow the app to download and install that staff. There might be keys, options for installation we don't know about.



x220 • Gobi 2000 3g | hdd, msata ssd, wwan, wifi, gps -- unique hand-made config
ThinkPad 25 Special Anniversary Edition. #retro. Signed by D.Hill
T470p | X1 Carbon Gen3 | Miix 2 10" | Yoga Tablet 2-1050F (Android) + BT Keyboard
ThinkPad Stack • 2.4/5 Wireless Router, HDD 1 TB, BT Speaker, Power Bank, Mobile Projector

Do it well, worse becomes itself

Communities:   English    Deutsche    Español    Portugues    Русскоязычное    Česká    Slovenská    Українська   Moto English

Community SeniorMod
Community SeniorMod
Posts: 9,236
Registered: ‎01-01-2010
Location: US
Views: 744
Message 5 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

Is this a real OEM screen or an aftermarket one? Some of the screen's capabilities are controlled by options in the eeid chip on the panel. 


Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
drdtyc
Paper Tape
Posts: 8
Registered: ‎10-02-2015
Location: Canada
Views: 729
Message 6 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

It seems to me that EDID is the problem.
It used MonInfo.exe to check that my HD+ LCD panel is an LG one with a EDID which is different from those mentioned in the URL below (See Posts #863 #864 and #865).

 

http://forum.notebookreview.com/threads/thinkpad-t420-owners-thread.568372/page-87

 

Here is the details of my LG panel:

 

Monitor
Windows description...... Generic PnP Monitor
Manufacturer............. LG Display
Plug and Play ID......... LGD0362
Data string.............. LP140WD2-TLD2
Serial number............ n/a
Manufacture date......... 2011, ISO week 0
Filter driver............ Monitor

drdtyc
Paper Tape
Posts: 8
Registered: ‎10-02-2015
Location: Canada
Views: 725
Message 7 of 7

Re: T420 LCD brightness problem after upgrade to 1600x900 HD+

Thanks.
I tried ThinkVantage Update.
But the LCD brightness problem is still there.

Check out current deals!


Shop current deals

Top Kudoed Authors