t400 screen brightness oddity!

Hi all,

I just received my t400 today and I love it. Something strange happens though when I go from being unplugged to plugged in. I have it set so that regardless of whether I'm plugged in or not, it's at the highest brightness. But I find that when I decide to go from unplugged to plugged, the screen dims drastically (even though the brightness meter that comes up when you do so says that I'm at maximum brightness.) So then I go to power options and try to change it there but the slider is at max brightness there too.

When I restart the computer and have it plugged in initially it's fine, but I can't figure out why it's doing this. I'm running windows 7.

Any help would be appreciated, thanks!

Edited to add: It doesn't do this every time I switch from UNplugged to plugged, but it has done it twice already and I've only had it for half a day.

 

Mine's been acting up too lately. I'll get back here when I get more details.

 

There should be a setting in the BIOS that says to automatically lower the screen brightness when on battery. You should change this setting to not do that.

 

Hi,

Thanks for the reply. But what's actually occurring is the opposite--the screen is perfectly bright when on battery, but when I plug the power supply back in, the screen dims unaccountably and does not react to me fiddling with the brightness settings.

 

My issue is that in Power Manager I would have the screen set to, say, 70% brightness when plugged in, and 20% when on battery. Let's say I am running unplugged and I turn the brightness to 50% and shut it down at that brightness. When I plug in and turn the laptop on, the brightness stays at 50% instead of upping to 70% like it should. When I open up Power Manager it shows the settings correctly but they are not applied.

 

just wondering, do you have the latest power manager software and utilities and whatnots installed? coz i had problems with the backlight with the beta win7 utilities/drivers, but everything works fine after i installed the official win7 utils

 

Hi Cassiohui,

I thought that may be the problem so I installed all the windows 7 updates and also went to the lenovo site to look for the latest drivers/utilities, but I was having trouble navigating the site to get to where I needed to be. If these needed drivers/utilities are located on the Lenovo site, could you give me some helpful directional tips? After filling out the form I was directed to a page that had a ton of utilities and I couldn't really see which one was the appropriate one. If they are not on the Lenovo site, where can I find them? (Excuse me if the answer is really obvious--I am a little braindead after a lack of sleep due to paper writing.)

 

just install system update 4.0 and it'll (or at least should) pull everything that you need.

 

Thats really weird. Do you have a CCFL display or LED? In my experience over two different laptops with WXGA+ CCFL displays the displays dims a bit when on battery. LED WXGA+ Displays do not seem to suffer from this.

The opposite of what you are seeing.

 

I have a similar issue here... when my T400 is docked and I'm outputting dual display to an external monitor (DVI) + T400's LCD, LCD brightness automatically goes to 100%, and I cannot adjust it! (ctrl-home/end brings up the brightness meter OSD, which changes, but the actual LCD brightness remains at 100%)

Mine is a T400 with Intel GMA 4500 MHD graphic adapter. I suspect it has something to do with the graphic adapter driver, but I can't be sure.

 

With Windows 7 mine does that too, doesn't matter which power plan I have it set on. I just FN + PgUp or PgDn depending on what I need. Think some of the drivers/thinkvantage stuff may not be 100% complete. If you aren't on Windows 7 then ignore my post.

 

i'm using win7, and i haven't had a problem with the screen brightness after updating to the latest utils and drivers

 

this is just a software problem or a bios firmware problem, i use to have these problems in my other thinkpads, but some of the bios update fixed the issue (but brought along other more troubling issues of improper CPU/GPU heat management).

 

I installed the system update 4.0 and it fixed the screen brightness issue.

http://www-307.ibm.com/pc/support/site.wss/document.do?sitestyle=lenovo&lndocid=MIGR-73695

After the installation was complete, it restarted the machine and when windows opened up, the brightness was now at max (how it was setup in the settings).