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Damage to electronic components
All electronic devices, such as computers, instruments, automobiles, etc., are all composed of different functional electronic components. The basic unit of electronic circuits is electronic components. These devices are in the form of hardware. They all have their own electrical components. Parameters such as voltage and current and power characteristics. Therefore, the components are the most vulnerable items, and the general faults are characterized by electrical parameter damage and physical damage, and the damage characteristics of these electronic components are respectively below.
Resistance damage characteristics:
Resistance is the most abundant component in electrical equipment, but it is not the component with the highest damage rate. Resistance damage is the most common with open circuit, the resistance value becomes smaller, and the resistance value becomes very small. Common carbon film resistors, metal film resistors, wirewound resistors and fuse resistors. The first two resistors are the most widely used, and their damage characteristics are: low resistance and high resistance have higher damage rate, and the intermediate resistance is rarely damaged; second, low resistance resistance is often burnt and black, very It is easy to find, and there are few traces when high resistance resistors are damaged. When the cylindrical wirewound resistor is burnt out, some may be black or have a surface blast, crack, and some have no trace. Cement resistance is a kind of wirewound resistor that may break when burnt out, otherwise there will be no visible traces. When the fuse is burned out, some surfaces will blow up a piece of skin, and some will have no trace, but it will never burnt and black.
Electrolytic capacitor damage features:
Electrolytic capacitors are used in large quantities in electrical equipment and have a high failure rate. Electrolytic capacitor damage has the following performances:
Completely lost capacity or capacity becomes small, slight or severe leakage or loss of capacity or capacity and leakage.
The methods for finding damaged electrolytic capacitors are:
Look: Some capacitors will leak when they are damaged. There will be a layer of oil on the surface of the circuit board under the capacitor or even the surface of the capacitor. This capacitor can never be used again; some capacitors will bulge after being damaged, and this capacitor can not be used any more.
Touch: Some electrolytic capacitors with serious leakage will heat up after starting up, and even hot when touched with fingers, this capacitor must be replaced.
There is an electrolyte inside the electrolytic capacitor. If it is baked for a long time, the electrolyte will dry out, resulting in a decrease in capacitance. Therefore, it is important to check the capacitance near the heat sink and high-power components. The closer to it, the more likely the damage is. Big.
Damage to semiconductor devices such as diodes and transistors:
Diodes, triode damage is generally PN junction breakdown or open circuit, which is mostly through breakdown short circuit.
There are also two types of damage performance:
First, the thermal stability deteriorates. It is normal when starting up. After working for a period of time, soft breakdown occurs. The other is that the characteristics of the PN junction deteriorate. Using a multimeter R×1k, each PN junction is normal, but It can't work normally after the machine. If it is measured with R×10 or R×1 low-range file, it will find that its PN junction forward resistance is larger than normal.
Features of integrated circuit damage:
The integrated circuit integrated circuit has a complicated internal structure and many functions, and any part of the damage cannot be operated 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. 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.