Signs of Damage in Electronic Components on Development Boards

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Electronic components have a lifespan that is closely related to their structure, properties, and the environment in which they are used, as well as their role in the circuit.

In a circuit, electronic components vary in strength, and the resistance capability ranking of electronic components is as follows:

Resistors, inductors, capacitors, semiconductor devices (including diodes, transistors, field effect transistors, integrated circuits). This means that, under the same working conditions, semiconductor devices have the highest probability of failure.

When looking for faulty components, priority should be given to checking diodes, transistors, field effect transistors, and integrated circuits. Generally, when semiconductor devices fail, breakdown is the most common occurrence. When measuring these components with a multimeter in diode mode, at least one PN junction should have a resistance of around 500 ohms. If it beeps, it is likely faulty; it can be removed and measured again for confirmation.

In circuits, components operating under high voltage, high current, and high power conditions undoubtedly bear greater stress and have a higher likelihood of failure. They are also key and functional components of the circuit.

Wherever there is high current, there is substantial heat (Joule’s law—heat is proportional to the square of the current), so any component with a heatsink is likely to be fragile. High-power resistors are also fragile components. In circuits, fuses and thermal resistors are the least reliable components; primarily because they have a low melting point and are prone to breaking, and because they serve to protect others, they are the first line of defense and thus fail first.

Components can fail due to overvoltage, overcurrent, or mechanical damage. Overvoltage damage can occur from lightning strikes, breaking bridge rectifiers. Overcurrent damage can occur from thermal breakdown in display driver tubes.

Overvoltage-damaged components do not show obvious external changes; only their parameters change. Overcurrent-damaged components have very high surface temperatures and exhibit cracks, discoloration, or small pits. In severe cases, the surrounding circuit board may turn yellow or black.

Common electronic components that appear normal can be subjected to simple tests with a digital multimeter.

Resistors:This is very simple; test whether the resistance value is correct.

Diodes:Test the forward voltage drop of the PN junction with a digital multimeter, and compare it with a good diode of the same model.

Transistors:Whether N-channel or P-channel, you can use a digital multimeter to measure if the two PN junctions are normal.

Field Effect Transistors:Test whether the internal diode of the field effect transistor’s PN junction is normal, and check if there is a short circuit between GD and GS.

Capacitors:Non-polarized capacitors can fail through breakdown shorts or soldering issues, severe leakage or resistance effects.

The actual characteristics of electrolytic capacitors are: breakdown shorts, increased leakage, reduced capacitance, or open circuits.

Inductors:The actual characteristics are:open circuits, soldering issues.

Chips:Integrated circuits have complex internal structures and many functions; any part that is damaged will prevent normal operation.Integrated circuit damage can also be of two types:complete failure or poor thermal stability.In complete failure, it can be removed and compared with a normal integrated circuit of the same model to measure the resistance of each pin to ground; one or more pins will always show abnormal resistance.For those with poor thermal stability, during operation, you can cool the suspected integrated circuit with anhydrous alcohol; if the fault occurrence time is delayed or no longer occurs, it can be determined.Usually, a new integrated circuit must be replaced to rule out the issue.

Whether faults arise from natural wear or human damage, they generally fall into three categories: open circuit connections, electronic component failures, and software faults. Open circuit connections, such as broken wires, disconnected plugs, or poor contact, are generally easier to repair. However, electronic component failures (aside from obvious burns and overheating) are often difficult to detect by observation alone; in many cases, instruments must be used for diagnosis. Therefore, for technicians, it is crucial to understand the effective characteristics of various components as this is extremely important for troubleshooting circuit faults and improving repair efficiency.

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