Метод комутація живлення живлення обслуговування
1. Коли ремонт комутація живлення живлення, перший використання a мультиметр до перевірте чи кожен потужність компонент is зламаний і короткозамикаючий, такий as the power випрямляч міст стек, switching tube, високочастотний високопотужний випрямляч трубка; чи той те висока потужність резистор that suppresses the перенапруга струм is видування. Потім перевірте чи the опір of each output voltage port is abnormal. If the above parts are damaged, they need to Be Замінений.
2. After the first step is completed, it still cannot work normally after turning on the power supply. Next, check the power factor module (PFC) and pulse width modulation module (PWM), consult relevant information, and be familiar with the function and function of each pin of the PFC and PWM module. A prerequisite for its modules to work right.
3. Then, for the power supply with PFC circuit, it is необхідні to measure hether the voltage at both ends of the filter capacitor is about 380}VDC. If there is a voltage of about 380VDC, it means that the PFC module is works normally. 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 2c use an oscillograph to observe the waveform of PWM module CT terminal to ground is a sawtooth wave or triangle with good linearity, such as TL494 The CT terminal is a sawtooth wave, and the CT terminal of FA5310 is is a трикутна хвиля. Чи форма хвилі of the output terminal V0 is an ordered narrow pulse signal.
4. In the practice of switching power supply maintenance, many switching power supplies use UC38×× series 8-pin PWM components. Most of the power supplies cannot work because the starting resistor of the power supply is damaged or the performance of the chip is degraded. When R is disconnected and there is no VC, the PWM component cannot work, and it is necessary to replace the resistor with the same resistance value as the original power. When the starting current of the PWM component increases, the value of R can be reduced until the PWM component can work normally. When repairing a GE DR power supply, the PWM module was UC3843, and no other abnormalities were found in the inspection. After connecting a 220K resistor to R (220K), the PWM component worked and the output voltage was normal. Sometimes due to peripheral circuit failure, the 5V voltage at the VR terminal is 0V, and the PWM component does not work. When repairing the power supply of the Kodak 8900 camera, when this happens, disconnect the external circuit connected to the VR terminal, and VR changes from 0V to 5V, the PWM component works normally, and the output voltage is normal.
5. When there is no voltage of about 380VDC on the filter capacitor, it means that the PFC circuit is not working normally. The key detection pins of the PFC module are the power input pin VC, the start pin Vstart/control, CT and RT pins and V0 pin. When repairing a Fuji 3000 camera, there is no 380VDC voltage on the filter capacitor on the test board. VC, Vstart/control, CT and RT waveforms, and V0 waveforms are all normal, and the measured field effect power switch G has no V0 waveform. Since FA5331 (PFC) is a patch component, there will be a virtual gap between the V0 terminal and the board after the machine has been used for a long time. Welding, the V0 signal is not sent to the G pole of the field effect tube. Solder the V0 terminal to the solder spot on the board, and use a multimeter to measure the voltage of the filter capacitor to 380VDC. When the Vstart/control end is low level, PFC cannot work either, and it is necessary to detect the relevant circuits whose terminals are connected to the periphery.
