Hi again,
Luckily I found RL207 fast recovery diodes in a near city. But I am sure it will also burn out after few weeks or months. I think the design around the diode is poor. All SMPS of the same model has problem on the diode and burns frequently.
According the example schematic at #1 post of mine, the diode seems like a protection diode (same as a diode across a relay coil). Sorry I wrote '1uF' in the schematic, it's actually 0.1uF, 400V . IC 'UC3843A' creates 500KHz and the MOSFET drives the transformer. So the 0.1uF capacitor acting there as a 3 ohms series resistors? (capacitive reactance of 0.1uF+500KHz is around 3 ohms.) And then a 22k 1watt resistor is a bleeder resistor for the capacitor?
I guess I can modify the R1 or C1 to solve frequent diode burning problem. How you think? (I didn't get more powerful diode than HER207 so thinking like this way)