How to identify the measurement key point voltage
Ac single-phase power supply voltage 220V and DC bus 310V voltage of the two power supply voltage, AC input power supply voltage naturally need not say much, directly use the multimeter AC file to measure, DC bus voltage with the DC file of the multimeter, take the red watch pen to take the positive electrode of the DC bus electrolytic capacitor, black watch pen to take its negative electrode, so that you can measure the DC bus voltage.
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The voltage of each pin of the power management chip is measured by the DC voltage file of the multimeter. The black watch pen is in pin 5 of the UC3844, and the red watch pen measures the voltage of pin 7, pin 5, pin 4, pin 6, pin 3, and pin 1 in sequence. Among them, 4 feet and 6 feet use the oscilloscope to measure the output waveform, and the pointer table can be used unconditionally to check the pointer swing into a certain law.
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The two output voltages of the switching power supply are 5V and 16V. If the switching power supply has the output voltage mark, it is measured directly in DC file. If there is no mark, the electrolytic capacitor of the secondary output circuit of the switching power supply is identified according to the electrolytic capacitor of the switching power supply. The 5V output loop electrolytic capacitor is 16V1000UF. Here, the digital meter does not distinguish the positive and negative capacitance, nor does it distinguish the red and black of the watch pen to directly measure the capacitor two pins is the output voltage