on battery your screen will get 7.7v of power, when the charger is connected it will get the full charger power (19.25v as you said)
Rododendron писал(а):
everything works fine with a brightness of no more than 80%
on 80% brightness the inverter ic on your screen will work at around 15v of power, no more...
long story short... you have a defective inverter ic in your screen that is not working on HIGH voltage
I've seen tons of Asus laptops with this disease, sometimes the defect is the opposite (on low voltage), the screen will work while charger is connected and will go off on battery power...
you can take it the hard-way if you have the experience & tools for it, replacing inverter ic/coil should fix that..
or just take it the easy-way and replace the whole screen
* try another screen to eliminate any suspicion of software related issues