My laptop's monitor gets dimmer compared to as

The problem is probably at your TFT/LCD panel. Find to know by connecting your Notebook to another monitor is it dimming or not

On AC or Battery? As I'm sure you know, your Laptop will dim the Display on Battery to save power. In Windows 7, Open the Control Panel, select Power Options, select High Performance, select Change Plan settings, set Display time, set Sleep and Hibernate to Never, select Change Advanced Power settings, scroll through each one by one and adjust. OR right click a open spot on the Desktop, select Personalize, left bottom select Display. adjust to your preference.

The Sony VAIO VGN-C140G/B manual indicates that it has the following video card:

Processor: Intel® Graphics Media Accelerator 950 on Intel's 950G chipset

The manual, if you require it, can be found at this link: VGNC140GB Manual

You could easily update the driver by using Intel's Driver Updater: Intel Driver Utility Update Graphic

You will likely need to do the same (updating driver) for your monitor. Please respond if updating both drivers doesn't solve your request.

wait so first of all brightness for computer .... you mean to say you hooked a monitor to your laptop right....
basically for adjusting brightness in laptop you need their proper graphic driver... eg. I have a lenovo with intel hd400
so yeah after the graphics driver you can adjust brightness

try to use only one monitor at the same time disable your laptop screen and try it on the sync master monitor. and adjust the resolution

Hi.
Just a general suggestion.
Are the graphics drivers loaded.
(Assuming you are using Windows) what happens when you rightclick on the desktop screen and you click on the Settings Tab

it is still on warranty... check on service ... or you can try to download drivers .. or new chipset for your laptop..
or on startup hit f and chose last known good configuration thaht worked.

try your laptop connected to an external monitor check if DIM issue can be seen from the external monitor if yes update the video driver.

CRT and LCD will look different when compared side by side. Is your CRT calibrated, or are they right in the sense that they are what you are used to? Also Anyway, you can adjust the colors and light levels from the menu on your screen, and depending on your operating system and graphics adapter you should be able to make adjustments there, too. For windows XP, right click your desktop and select properties->Settings->Advanced. There might be a color management tab. Also, there might be software to help you do this already installed. Look for a program group with the name of your Graphics adapter manufacturer. Very often ATI or nVidia. A few resources to help calibrate: http://desktoppub.about.com/od/visualmonitor/Visual_Monitor_Calibration_Tests.htm http://desktoppub.about.com/od/visualmonitor/Visual_Monitor_Calibration_Tests.htm