How to use a multimeter to find short circuits, open circuits and leakage
A multimeter is one of the most commonly used tools for electricians, maintenance personnel, electronic engineers, and hardware engineers. It is essential for detecting electronic circuits and locating faults. A small multimeter has powerful functions, such as measuring resistance, capacitance, diodes, transistors, DC voltage, AC voltage, current, etc. Finding short circuits, open circuits, and leakage is the most basic function of a multimeter. Learn to use a multimeter and handle simple faults yourself.
How to use a multimeter to find short circuits
Short circuit measurement is commonly used in electrical maintenance and component fault location. When measuring short circuit faults, it is necessary to ensure that the power is disconnected and do not operate with live power. Short circuit measurement is carried out using the buzzer or ohm range of the multimeter. Using the buzzer for measurement is more intuitive. When the circuit is short circuited, the multimeter will directly "beep". The principle of the buzzer range is that when the measured resistance is less than about 75 Ω, the multimeter will beep. If you want to more accurately know the resistance between two circuits, you can use the 200 Ω range for measurement. When using the buzzer mode for measurement, sometimes the actual internal resistance between two signals is small, which can easily lead to misjudgment. For example, in the case of relay/contactor coils, many relay/contactor coils have an impedance less than 75 Ω. When using the buzzer mode for measurement, it may sound like a short circuit, but in reality, it is not.
Engineers often use a multimeter buzzer to quickly locate the fault point of a short circuit in a circuit or component, such as measuring whether the resistance or capacitance is short circuited, whether the diode is reverse broken, whether the transistor is broken down (usually the base and emitter are short circuited when the transistor is broken down), whether there is a short circuit between the power supply and ground of the integrated circuit chip, and whether there is a short circuit between two pins.
