Switch mode power supply Auxilary transformer winding issue

[Ayyaz Ali]

hi, i saw one of the video blog for switch mode power supply MANSON SPS-9400 15v-40Amps and i planned to built it,i have little issue in winding the auxilary transformer in it as it is using a TOP222Y for oscillations generation, and my wrong turn ratio calculations makes the TOP222y to cook in a matter of seconds, i have read many research papers, switchmode power supply books by where they have given formulas for winding a flyback transformer but still the best i can get is my winding ratio now makes the TOP222y to become too hot in about 10 seconds while the output voltage is just fine. So anybody with the same experience please give me some suggestions of what to do.
Thanks

[albert22]

It is possible that the core that you used is saturating. Depending on the type of the core material it may need an air gap to allow Flyback operation and prevent saturation.