AC 220V after D7401 bridge rectifier obtained 300V DC voltage, the way is added to the standby power oscillation circuit IC7401, way is added to the standby power transformer T7401 the ~ 4 coil. 300V D7406 IC7401 added to the voltage of the foot, as starting power supply voltage of IC oscillation. IC7401 from the output 8VP of a drive pulses to switch Q7401 g, in under the action of the driving pulse Q7401 periodic guide through and cut, in T7401 secondary winding and the auxiliary winding of the pin output pulse shape of the induced voltage. The auxiliary coil is connected to the end of the second, and the induced voltage is generated by the D7408 rectifier and the C7407 filter is obtained from the 14.7V voltage, which is called "self feeding" (IC7401). Also, induction voltage generated by the terminal 2 is the D7409 rectifier, C7408 filter are 14.6V supply voltage, is divided into the following several road: a road for three power relay line power supply package, all the way through the Q7708 PFC oscillation IC7201 power supply and a road through the Q7710 based switching power supply IC7301 power supply. Finally a way to supply power to the AC detection circuit.

In T7401 Secondary 7 to the winding, the end of the grounding, induction voltage of the end of the D7651 rectifier, C7601 filtering obtained 6V standby power supply voltage STB6V, P2 sockets are connected through a Q7601 output to power plate and a plate 20, 22, 23 feet, then output to the motherboard.

D7602 is an overvoltage protection diode. R7603, R7604, R7605 STB6V output voltage division sampling resistance pressure and share in the upper end of the R7605 voltage sampling, IC7601 added to the error amplifier input end and amplified inverted phase from K inverting output voltage control, added to the PC7401 internal luminous negative end of the tube. When STB6V output voltage rises, sampling overvoltage at the upper end of the R7605, IC7601 of K terminal voltage drops, optocoupler in light emitting diodes become strong, photosensitive audion resistance becomes smaller, the very C voltage drop, the IC7401 voltage feedback end feet voltage drop, which will enable the output positive drive square wave narrow, so that STB6V T7401 output is stabilized in the standard 6V.

IC7401 the foot to indirectly have a soft start capacitor, the foot is connected with a switch tube overcurrent protection. Q7401 S pole current through current sampling resistance to R7403, R7404 to ground and the resistance to the current into a voltage. By the feet of the added to the R7409 IC7401. When the flow through the switch tube current is too large, added to the foot of a voltage rise. This will trigger IC internal Overcurrent protection circuit, and cut off the output driven square wave, eliminate the phenomenon of over current.