Why is the screen brightness not adjustable?

Question

Windows

So the laptop Lenovo n580 was broken matrix and replaced. After the replacement, the brightness is no longer adjustable. It is regulated only in 2 modes: maximum and minimum.
OC- Windows 7 Ultimate was installed .
When I installed Windows 8.1, then it is regulated normally. And on Windows 7 does not want.
Is it possible to set it up on windows 7 as well??

Answer 1

Try the control panel / power supply. Or look at the map settings...

Answer 2

Pkm on the desktop - the screen resolution
should indicate the exact name of the matrix, for example
LG-Philips LP133WX2 (TL) (E1)
if not, then (IMHO) you need to look for drivers for it