Identification and detection of circuit board components

Date：2021-10-22 15:28:00Views：1187

For beginners of electronic technology, mastering the basic circuit principle, the functional characteristics and detection of components, and how to analyze the schematic diagram are all basic skills that need to be mastered. Here's how to identify the components on the circuit board? Circuit boards often need maintenance. What are the rules for the maintenance of industrial PCB circuit boards? The components on the circuit board should not only be known, but also the vulnerable parts on the circuit board during maintenance.

There is a big difference between the component layout on the circuit board and the schematic diagram, which will make beginners feel "complex". In fact, there are skills to understand the components on the PCB.

1. When actually analyzing the circuit board, first, according to its shape, see what components this component looks like. However, the accuracy is not high. You have to look more at it at ordinary times.

2. Secondly, it is identified in combination with the printing of the components themselves. Generally speaking, the printing expresses some parameters or models. Of course, it also has attributes such as the manufacturer's batch number and version number, and some international certification symbols. This method also depends on the usual understanding of the component models and parameters. Thirdly, you can disassemble the components to see the internal structure. The components of a certain type and series have the same or similar structural characteristics. If they are disassembled more, they are more familiar with the internal structure and working principle of the components. You can disassemble as many components as possible to further improve your basic component knowledge.

3. If the components are on the circuit board, it shall be judged according to the component symbols and silk screen printing on the board. If it is marked R12, it is the resistance, which is numbered 12 in the circuit. 10. Y and Z can represent crystal oscillator. At the same time, you can judge the function of components according to their circuit, and then analyze what kind of components they belong to, which requires you to be familiar with the basic circuit.

1、 Places with unreasonable design are most likely to fail

What are the unreasonable places of industrial circuit board design? The first is the problem of heat dissipation. Many circuit boards are damaged due to poor heat dissipation design; The second is the copper foil wire of the printed board. The copper foil of the power supply line of the circuit board with poor quality is very thin, which is easy to burn out due to overcurrent, making the main board unable to work.

1. The frequently used places are prone to failure, such as the driving motor of industrial circuit board, rotating shaft, switch tube of switching power supply, common buttons of operation panel, etc.

2. Components with heavy load, high power and high working voltage are most likely to fail. The power supply, driving circuit, power control device, transportation and discharge of industrial circuit board are the most vulnerable to damage. These components are usually close to the radiator. If the protective measures are not enough and the heat dissipation is not good, it is easy to become the first victim.

3. The protection circuit is most vulnerable to damage. All expensive chips or components on the circuit board are protected. Once the equipment is abnormal, these protection circuits will be sacrificed first. During maintenance, these protective devices can be identified at a glance.

4. Inline seat The interface and wiring of the connector are easy to be in poor contact or broken. For example, the board is in poor contact with the slot, the cable is usually blocked when the cable is broken, the cable plug is in poor contact with the wiring terminal, component faulty welding, etc.

2、 Damage characteristics and detection of common components of industrial circuit board

The damage of industrial circuit board is usually the damage of a component, which may be a chip, a capacitor or even a small resistance. The maintenance process is to find out the damaged parts and replace them.

1. Capacitors with small resistance and large capacity are easy to break

The resistance with small resistance value is often used for current limiting of power supply line, that is, it plays the role of fuse. If the current is too large, it will burn out first. In addition, a large number of ground capacitors are used for filtering on the power supply line, which is generally large in size and capacity. If the voltage or current is unstable, it will break through the capacitor and cause leakage.

2. Fault characteristics and maintenance of capacitor damage

In electronic equipment, capacitor damage causes the most faults, especially electrolytic capacitor damage. Capacitor damage: 1 Capacity reduction; 2. Complete loss of capacity; 3. Leakage; 4. Short circuit.

3. Methods to judge whether the amplifier is good or bad

No matter what type of amplifier, there is feedback resistance RF, so we can check the feedback resistance from the circuit during maintenance and check the resistance between the output and reverse input with a multimeter. If it's outrageous, like how many ω Above, we can be sure that the device is used as a comparator; If this resistance is less than 0 ω To dozens ω， Check whether there is resistance between the output end and the reverse input end. If so, be sure to make an amplifier. According to the principle of virtual short of amplifier, that is, if the amplifier works normally, the voltage at the same input and reverse input must be equal!

3、 The maintenance shall have a block diagram in mind

How to repair industrial equipment without relevant information? You can draw inferences from one instance. For example, switching power supply is always inseparable from oscillation circuit, switching tube, switching transformer, etc. During inspection, check whether the circuit vibrates, whether the capacitor is damaged, and whether the triode and diode are damaged. In addition, pay attention to the maintenance sequence during maintenance, so as to find the shortest path to solve the problem and avoid random poke and disassembly, failure of maintenance and expansion of fault.

In conclusion, due to the reasons of technology, manufacturer and manufacturer, the same component will have different shapes, structures and materials. More understanding and accumulation will be of great help. I hope this article will be helpful to you, and we will bring more wonderful content in the later stage. Our testing services include: electronic component testing and verification, IC true and false identification, product design and material selection, failure analysis, function testing, factory incoming material inspection, tape braiding and other testing items. Warmly welcome to call, we will serve you wholeheartedly.