I have two problem with non-isolated flyback LNK419 driver.
1) Some of my driver failure because of Bias Capacitor 10uF 25V( X7R Samsung Original). It happen even after 2 months.
When I change this capacitor it's start again.
It's take 2-3 Watt power with no output at failure time. I checked each & every components but all are working fine.
This failed capacitor shows correct capacitance with LCR meter.
2) Current increses upto 12% with temperature rise in driver.
Driver details are below.
Input : 220V 50hz
Output : 58Volt, 350mA, 20Watt , PF 0.98
Efficiency : 88%
I have attached circuit & PCB layout.