We have a three year old LG television.
A few days ago I figured it was not as bright as I'd like it.
Thought there must be an adjustment in 'settings' - soon found it. 
Slid the adjustment bar from 50 to 85.
Went back to the program we were on - the Commonwealth Games  - from Edinborough in Scotland.
Bit brighter -  but soon, as in a few minutes, seemed to be dull again.
Sifted the ' brightness' bar to 100.
But soon the picture was dull again.   Think the LG is stuffed!
Need a replacement!
What brand do NAT recommend?
TIA