1, repair power supply, the first to use a multimeter to test the breakdown short-circuit power components, such as power bridge rectifier, switch, high-frequency power rectifiers;
Suppression surge current power resistors burned.
Resistivity anomaly detection output voltage port, damaging some of these need to be changed.
2, after completing the first step in turning the power does not work, then the detection module power factor (PFC) and pulse width modulation (PWM) module, please refer to the relevant information, are familiar with the PFC and PWM modules and functions necessary for each foot normal operating conditions of the module.
3, then the filter capacitor voltage PFC circuits at both ends of the power measurement is about 380 volts DC, if you have 380 volts DC voltage, PFC module to work, and then detecting the working status, measured PWM module power input VC, VR reference voltage output, the speed of sound start to start the control voltage / Vcontrol is normal, using 220 vac / 220 vac isolation transformer, switching power supply, CT using an oscilloscope to observe the end of the PWM module is a linear sawtooth waveform and triangle, such as TL494 CT end sawtooth, FA5310 its CT triangular wave.
Output terminals V0 narrow pulse waveform signal is ordered.
4. The practice of switching power supply repair, there are a lot of PWM switching power supply series with UC38 x 8 foot assembly, most of the power can not work because of power starting resistance damage, or chip performance.