What are the performances of various electronic components after damage?

There is life and death, and electronic components have a long life. The life of an electronic component is closely related to its structure and nature, as well as its use environment and its role in the circuit.
When the winter is coming, there is a cold current, some of the body is poor, can not stand the cold and hot changes of the environment, fever, but the strong body is strong, no sick. This shows that illness is related to your own constitution.
                              
There are also physical strengths in the circuit, and the resistance list of electronic components is as follows:
Resistors, inductors, capacitors, semiconductor devices (including diodes, transistors, field tubes, integrated circuits), that is, under the same operating conditions, semiconductor devices are most likely to be damaged.
Therefore, when we look for faulty components, we must first check the diodes, transistors, field tubes, integrated circuits, etc. Generally, when the semiconductor device is damaged, the breakdown is more common. The multimeter diode buzzer test should have a minimum of PN on any two feet of these devices. The resistance of the knot is about 500. If the buzzer is 80%, it can be removed and tested to confirm.
We all know that the scorpion in the early days is bad, and the head guards are ready to sacrifice at any time, which shows that the job determines the degree of danger.
In the circuit, components operating under high voltage, high current, and high power are undoubtedly subjected to large pressures, and are highly likely to be damaged. They are also key components and functional components of the circuit.
Where the heat is generated at a large current (the Joule's law - the heat is proportional to the square of the current), so any component with a heat sink is a consumable. High-power resistors are also wearing parts. How can high power resistors be seen? It has nothing to do with its resistance, only related to its volume. The larger the volume, the greater the power. In the circuit, the fuse and the fuse are the most unsafe components. First of all, because of its low melting point, it is easy to break, and because it is the danger of protecting others, it rushes to the front line and acts as a security guard, so it is bad when it is bad.
The way the components are damaged is overvoltage damage, overcurrent damage and, of course, mechanical damage. Overvoltage damage such as lightning strikes, breakdown of the bridge rectifier. Overcurrent damage such as thermal breakdown of the display tube.
There are also various ways to die in response to people. Overpressure damage such as daggers, the head is lost, the person is dead, and the body is intact. The appearance of the component damaged by overvoltage does not show any significant change, but the parameters are completely changed. Over-current is like a beating death. It can be banned at first, and it is getting worse and worse. When it is dead, it is already bruised and bloody. Over-current damaged components have high surface temperatures, such as cracks, discoloration, and small pits. In severe cases, the circuit board around the component turns yellow and black.
Common electronic components can be used to do some simple tests with a digital multimeter when the appearance looks abnormal.
resistance
This is very simple, the test resistance is right.
diode
Use a digital multimeter to test the voltage drop of the PN junction, which can be compared with a good diode of the same model.
Transistor
Whether it is N tube or P tube, you can use a digital multimeter to measure whether the two PN junctions are normal.
Field effect transistor
Test whether the PN junction of the body diode of the FET is normal, and test whether GD or GS has a short circuit.
capacitance
Non-polarity capacitor, breakdown short circuit or desoldering, severe leakage or resistance effect.
The effective characteristics of the electrolytic capacitor are: breakdown short circuit, increased leakage, small capacity or open circuit.
inductance
The effective characteristics are: disconnection, desoldering
chip
The internal structure of the integrated circuit is complex and has many functions, and any part of the damage cannot work normally. There are also two types of damage to integrated circuits: complete damage and poor thermal stability. When it is completely damaged, it can be removed, and the positive and negative resistance of each pin to ground can be measured compared with the normal integrated circuit of the same type. It is always found that one or several of the pins have abnormal resistance. For poor thermal stability, the suspected integrated circuit can be cooled with absolute alcohol while the device is in operation, and can be determined if the time of failure is delayed or no longer occurs. Usually only new integrated circuits can be replaced to eliminate them.
Whether it is a fault caused by natural loss or a fault caused by man-made damage, it can generally be attributed to three faults: circuit contact open circuit, electronic component damage and software fault. If the contact is open, if the wire is broken, the plug is disconnected, the contact is bad, etc., it is generally easier to repair. The damage of electronic components (except for obvious burnout and heat) is generally difficult to be discovered by observers. In many cases, it is necessary to use instruments to detect and judge. Therefore, for technicians, it is necessary to understand various devices first. The effectiveness of this feature is extremely important for troubleshooting circuit faults and improving inspection efficiency.