Input source voltage supplied to the transformer is also supplied through {TAIL ~ a start up circuit} to drive {HEAD ~ the pulse width modulator} and the main power switch 
Input source voltage supplied to the transformer is also supplied through { TAIL ~ a start up circuit } to drive { HEAD ~ the pulse width modulator } and the main power switch
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH