one
If it is bad, the most common is breakdown damage, you can use a multimeter to measure the resistance or voltage of the chip's power supply end to the ground, generally if within dozens of ohms or the power supply voltage is lower than normal, most can be regarded as breakdown damage, you can disconnect the power supply end, and measure whether the power supply is normal. If the resistance measured is large, it is likely that other ports are damaged, you can also measure other ports one by one. See if there is a short-circuit port to the ground.
two
Specifically designed to detect IC instruments, multimeters do not have this ability. Generally, the use of multimeters is to detect the pin voltage when it is used to make an approximate judgment, and there is no reliability. And the judgment is made under the condition of extremely familiar with this IC.
The answer is as follows: Rice cooker power chip detection method is as follows:
1. Use a multimeter to test whether the resistance on the power chip is normal.
2. Perform a voltage test using a multimeter to check whether the input voltage and output voltage of the power chip meet specifications.
3. Check whether the capacitor, resistor, diode and other components around the power chip work properly.
4. Use oscilloscope for waveform test to check whether the output waveform of the power chip is normal.
5. Check whether the pin of the power chip is in good contact and whether it is loose or broken.
6. If the above tests are normal, but the rice cooker still does not work properly, it may be necessary to replace the power chip.
①→ This fault first measure whether the voltage of the microprocessor power supply pin is normal (normal is 5V) ②→ Detect whether the reset voltage of the microprocessor chip is normal (normal is 5V) ③→ Detect whether the crystal oscillator connected to the microprocessor chip pin is damaged.
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[This exam rate will be changed if necessary]