Electronic components are the cornerstone of the electronics field. They constitute both large and small electronic devices. To enhance your understanding of electronic components, this article will introduce electronic components and their failure characteristics.
I. Electronic Components
Electronic components are parts of electronic devices and small machines and instruments. They typically consist of several parts and are used in similar products; it generally refers to components in electrical appliances, radios, instruments, and other industries. It is a general term for electronic devices such as capacitors, transistors, hairsprings, and springs. Diodes are a common example.
Electronic components include: resistors, capacitors, inductors, potentiometers, electron tubes, heat sinks, electromechanical components, connectors, discrete semiconductor devices, electroacoustic devices, laser devices, electronic display devices, optoelectronic devices, sensors, power supplies, switches, micro motors, electronic transformers, relays, printed circuit boards, integrated circuits, various circuits, piezoelectric materials, crystals, quartz, ceramic magnetic materials, printed circuit boards, special materials for electronic functional processes, electronic adhesives (tapes), electronic chemical materials and components, etc.
Regarding the quality of electronic components, we have obtained domestic and international certifications such as EU CE certification, US UL certification, German VDE and TUV certifications, and China CQC certification, ensuring the quality of our components.
II. Fault Characteristics of Electronic Components
Although electrical equipment contains a large number of electronic components, their failures follow a pattern.
1. Characteristics of resistor failure
Resistors are the largest components in electrical equipment, but not the ones with the highest failure rate. Open circuits are the most common type of resistor failure. Increasingly low resistance is rare. Common types include carbon film resistors, metal film resistors, wire-wound resistors, and fuse resistors.
The first two types of resistors are the most widely used. Their damage characteristics are that the damage rate of low resistance values (below 100Ω) and high resistance values (above 100kΩ) is relatively high, while the damage rate of medium resistance values (such as hundreds of Ω to tens of thousands of Ω) is very low. Secondly, low resistance resistors are often burned black when damaged, which is easy to detect, while high resistance resistors are rarely damaged.
Wire-wound resistors are generally used for high current limiting and have relatively small resistance values. When cylindrical wire-wound resistors burn out, some will turn black or crack on the surface, while others will show no signs of damage. Cement resistors are a type of wire-wound resistor; they may break when burned, otherwise, there will be no visible trace. When fusible resistors burn out, some will have a piece of their surface chipped off, while others will show no signs of damage, but they will never burn out or turn black. Based on these characteristics, we can focus on inspecting the resistors to quickly identify the damaged ones.
2. Characteristics of electrolytic capacitor failure
Electrolytic capacitors are widely used in electrical equipment but have a high failure rate. Damage to electrolytic capacitors can manifest in several ways: first, complete loss or reduction of capacitance; second, slight or severe leakage; and third, capacitance loss or reduction accompanied by leakage. Methods for locating damaged electrolytic capacitors include:
(1) Note: Some capacitors leak liquid when damaged. A layer of oil may appear on the circuit board beneath the capacitor and even on the capacitor itself. Such capacitors cannot be reused; some capacitors bulge after damage and should no longer be used.
(2) Touch: Some electrolytic capacitors with severe leakage will heat up after startup, and may even become hot to the touch. These capacitors must be replaced.
(3) Electrolytic capacitors contain electrolyte, which can dry out during prolonged baking, reducing capacitance. Therefore, it is necessary to focus on inspecting capacitors near heat sinks and high-power components. The closer the capacitors are, the greater the likelihood of damage.
III. Damage Characteristics of Semiconductor Devices such as Transistors
Transistor damage typically occurs when the PN junction breaks down or becomes open-circuited, with breakdown and short circuit being the most common. In addition, there are two other types of damage: one is poor thermal stability, where the transistor works normally at startup but experiences soft breakdown after a period of operation; the other is a deterioration in the characteristics of the PN junction. Measurements using a multimeter with an R×1kΩ rating show that all PN junctions are normal, but the transistor fails to function properly in the machine. If the multimeter has an R×10Ω or R×1Ω rating, the forward resistance of the PN junction is higher than normal when measured at low ranges.
Diodes and transistors can be measured in a circuit using an analog multimeter. A more accurate method is to set the multimeter to the R×10 or R×1 range (usually R×10, use R×1 if the difference is unclear). Measure the positive and negative resistances of the PN junction of the diode and transistor in the circuit. If the positive resistance is not too high (relative to normal), and the reverse resistance is sufficiently high (relative to a positive value), the PN junction is normal. Otherwise, it is questionable and requires retesting after soldering. This is because the external resistances of diodes and transistors in general circuits are mostly greater than several hundred or several thousand ohms. By measuring the low resistance of the multimeter in the circuit, the influence of external resistance on the PN junction resistance can be largely ignored.
