1. Appearance inspection method by observing whether the circuit board has scorched places, whether the copper plating is broken, whether there are smells on the circuit board, whether there are poor soldering places, whether the interfaces and gold fingers are black and white, etc.
2. General method.
All components are tested again until the problematic component is found, and the purpose of repair is achieved. If a component that cannot be detected by the instrument is encountered, a new component is used to replace it, and finally all components on the board are guaranteed It is good to achieve the purpose of repair. This method is simple and effective, but it is powerless for problems such as through holes, broken copper, and improper adjustment of potentiometers.
3. The comparison method.
The comparison method is one of the most commonly used methods for repairing circuit boards without drawings. Practice has proved to have very good results. The purpose of detecting failures is by comparing with the status of good boards. Curve to find anomalies.
4. Working condition.
The working condition is to check the status of each component during normal operation. If the status of a component during operation is not in accordance with the normal status, the device or its affected parts are defective. The state method is the most accurate method to judge among all maintenance methods. The difficulty of operation is also beyond the grasp of general engineers. It requires a wealth of theoretical knowledge and practical experience.
5. Setting the circuit.
Setting the circuit method is to make a circuit by hand, the circuit can work after installing the integrated circuit, so as to verify the quality of the integrated circuit under test. This method judges that the accuracy rate can reach 100%, but there are many types of integrated circuits to be tested, and the packaging is complicated.
6. Principle analysis
This method is to analyze the working principle of a board. Some boards, such as switching power supplies, require engineers to know their working principles and details without drawings. For engineers, knowing their schematics is extremely simple to maintain.