in this video i explained how does computer atx 200 Watt PSU SMPS switch mode power supply works. i explained diagram step by step so it will very helpful in smps troubleshooting and easy repair. br because the repair man must know how does the circuit works.br computer ATX power supply have input EMI filter, MOVs, NTC, dual line inductor filter bridge rectifier and capacitor to charge at specific dc level, br after that there is standby power supply which generates , VCC for PWM controller. PG power Good signal is generated after voltage level verification by level comparator. PWM controller receives power ON command from CPU and starts switching, which drives the Inverter section BJTs, MOSFETs, IGBTs, and we receive +12 Volt, - 12 Volt, +5 Volt -ve 5 volt 3.3 volt which is further purified by stabilization circuit.