When decorating a house, it is the decoration material that is indispensable. When we choose it, we also pay attention to its quality. There are many types of decoration materials, and switching power supply is one of them. How do we choose it? So everyone knows what is the working principle of switching power supply? Today, Xiaobian will take a look at the working principle of switching power supply. Switching power supply purchase tips!
Switching power supply works:
1. In a linear power supply, the power transistor is working, and the linear power supply causes the PWM switch power supply to be closed or disconnected. In the closed and open states, the voltage of the power transistor is relatively small. It will produce a lot of current. When the switching power supply is turned off, it is reversed. The voltage is large and the current will be extremely small. The controller that controls the working principle of the switching power supply is to be better. Maintain stability and bring safety to people's living environment.
2. When the working principle of the switching power supply is running, the switching power supply is also a certain working condition. For example, the switch is not in a linear state when working, but is in a state of being switched under the operation of the electronic appliance; in addition, the DC, the switch When the power supply is working, it is DC, not AC; the high frequency of the last switching power supply is high frequency under the working condition of the electronic appliance, not close to the low frequency state of the work! In the working principle of the switching power supply, these work The conditions are certain.
Switching power supply purchase tips:
1. When repairing the switching power supply, first use a multimeter to check whether the power components are short-circuited, such as the power rectifier bridge, the switch, the high-frequency high-power rectifier, and whether the high-power resistor that suppresses the inrush current is blown. Then check if the output voltage of each output voltage is abnormal. If these parts are damaged, they need to be replaced.
2. The first step is completed. After the power is turned on, it still cannot work normally. Then, the power factor module (PFC) and the pulse width modulation component (PWM) are detected. Check the relevant information and familiarize with each function and module of the PFC and PWM modules. Prerequisites for normal work.
3. Then, for a power supply with a PFC circuit, it is necessary to measure whether the voltage across the filter capacitor is about 380 VDC. If there is a voltage of about 380 VDC, the PFC module works normally. Then detect the working state of the PWM component, measure its power input terminal VC, reference voltage output terminal VR, start control whether the voltage of Vstart/Vcontrol terminal is normal, use 220VAC/220VAC isolation transformer to supply power to the switching power supply, observe the PWM module CT end with oscilloscope Whether the waveform of the ground is a linear sawtooth wave or a triangle, such as the TL494 CT end is a sawtooth wave, and the FA5310 has a CT wave at the CT end.
4. In the practice of switching power supply maintenance, there are many switching power supplies that use UC38×× series 8-pin PWM components. Most power supplies cannot work because the power-on resistors are damaged or the performance of the chips is degraded.
5. When there is no voltage of 380VDC on the filter capacitor, the PFC circuit does not work normally. The key detection pin of the PFC module is the power input pin VC, the start pin Vstart/control, the CT and RT pins and the V0 pin. When repairing a Fuji 3000 camera, test that there is no 380VDC voltage on the filter capacitor on the board. The VC, CT and RT waveforms and the V0 waveform are normal. The measured field effect power switch tube G has no V0 waveform, because FA5331 (PFC) is posted. The chip component, after the machine is used for a long time, there is a virtual soldering between the V0 terminal and the board, and the V0 signal is not sent to the FET of the FET.
When we choose a switching power supply, we need to know how it works. Of course, its quality is also an important part. The above is the working principle of the switching power supply and the switching power supply purchasing skills introduced by Xiaobian today. I want to know more information, please continue to pay attention to the decoration home.
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