Zhou:
I revewed all e-mail.
I recommend the removal of all output loads from this converter. Physically measure the voltages at the pins of the converter:
1. Pin 1(Vs) to Pin2 (input ground)
2. Pin2 to pin 14 input sync. pin If no voltage is present on this pin 14 then evaluate for possible ground connection
3. If pin 14 has voltage, then
Measure voltage between pin 5(OVout) to pin 6
measure voltage at pin 8 Sync out pin to ground pin 5.
Sent me results of these tests.
Thanks
Tom