Hi ,i have a problem with Zeppelin air power supply.The both mosfets was in shortcircuit,R31,R34 and T9 defective.I replace mosfets,R31,R34,T9(with bc817 npn transistor) ,FAN7387,and the fuse,i remove the triac from the board(i use it at 220v) .the power stars,but the chooper trafo have a verry loud noise (high pitch noise,like is in short or oscillating),the mosfets became hot very quickly ,and at high volume intrerrupts soud and distors.I check C7 and C8,i replace C5 and C31,and i change all the capacitors in secondary..but the same.Any sugestion?