Common repair methods for SMT!

- Sep 18, 2019-

Common repair methods for SMT!

Visual inspection

It is possible to check for the failure of the smt patch by visual, olfactory, auditory, and tactile.

Visually check the wiring, smt patch solder joints, components are wrong, after confirming the correct installation of the battery, give the radio power to listen to the sound, if there is no smell, there is no burnt taste, and touch the transistor by hand Whether it is hot or not, see if there is a crack in the electrolytic capacitor.

2. Resistance method

Use MF47 multimeter to check whether the resistance value of the resistor chip component in the circuit is correct, check whether the capacitor is broken, breakdown or leakage, and check whether the crystal diode and transistor are normal.

3. Voltage method

Use the MF47 multimeter DC voltage file to detect the power supply. The static working voltage of the transistor is correct. If the cause is not found correctly, the AC voltage value can also be detected.

4. Waveform method

Check the circuit waveform with an oscilloscope. In this case, you need to perform an external signal input, and use an oscilloscope to check the output waveform of each transistor.

5. Current method

Use the MF47 multimeter DC current file to detect the collector quiescent current of the transistor to see if it meets the standard.

6. Component replacement method

After the above inspection, if you suspect that a component has a problem, you can replace the component with the same specifications and good components. If the circuit works properly after the replacement, the original replacement component is damaged. This method should not be used for components with higher cost, because if it is not damaged, it will cause unnecessary waste. For higher cost components, components must be replaced before they can be replaced.

7. Step by step separation method

The step-by-step separation method can take the method of checking from the previous level to the latter level, or it can take the method of checking from the latter level to the previous level. Set test breakpoints between the levels so that the test range can be narrowed down during the test, step by step, which makes it easier to check where the fault is located.

The above is the commonly used detection and repair method for SMT patches provided by Peng Zexiang Technology.

Visual inspection

It is possible to check for the failure of the smt patch by visual, olfactory, auditory, and tactile.

Visually check the wiring, smt patch solder joints, components are wrong, after confirming the correct installation of the battery, give the radio power to listen to the sound, if there is no smell, there is no burnt taste, and touch the transistor by hand Whether it is hot or not, see if there is a crack in the electrolytic capacitor.

2. Resistance method

Use MF47 multimeter to check whether the resistance value of the resistor chip component in the circuit is correct, check whether the capacitor is broken, breakdown or leakage, and check whether the crystal diode and transistor are normal.

3. Voltage method

Use the MF47 multimeter DC voltage file to detect the power supply. The static working voltage of the transistor is correct. If the cause is not found correctly, the AC voltage value can also be detected.

4. Waveform method

Check the circuit waveform with an oscilloscope. In this case, you need to perform an external signal input, and use an oscilloscope to check the output waveform of each transistor.

5. Current method

Use the MF47 multimeter DC current file to detect the collector quiescent current of the transistor to see if it meets the standard.

6. Component replacement method

After the above inspection, if you suspect that a component has a problem, you can replace the component with the same specifications and good components. If the circuit works properly after the replacement, the original replacement component is damaged. This method should not be used for components with higher cost, because if it is not damaged, it will cause unnecessary waste. For higher cost components, components must be replaced before they can be replaced.

7. Step by step separation method

The step-by-step separation method can take the method of checking from the previous level to the latter level, or it can take the method of checking from the latter level to the previous level. Set test breakpoints between the levels so that the test range can be narrowed down during the test, step by step, which makes it easier to check where the fault is located.

The above is the commonly used detection and repair method for SMT patches provided by Peng Zexiang Technology.


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