I have made non-isolated power supply using LNK409 with following config.
IN : 185-240V
Ou : 70V 400mA
Power Factor : 0.981
Efficiency : 88.5%
This power supply can also output upto 50Watts. I am using it for 30W output.
But When I change the IC it will change the output upto 20%. Also tried changing different IC for Different PCB.
But the problem is LNK409.
I note that there is number on IC like 1113,1112,1046...etc
Output changes with these number.