A method for detecting resistance components using a multimeter.

The use of multimeter to detect resistance components is often encountered by electricians and electricians. This article introduces the detection methods of this kind of components.

1. Detect considerations.

A multimeter is used to measure the resistor. The error of measuring resistance by the pointer multimeter is mainly determined by the head error, the scale error and the reading error. The larger the resistance of each block is, the larger the resolution error is.

1.1. Appearance check.

To judge whether a resistor is good or bad, it should first be judged from its appearance. Observe whether the surface coating of the resistor is discolored and damaged. Because when the resistor burns, its surface often blackens or discoloration. From the appearance, we can judge more rapidly and intuitively.

When testing the resistor with a multimeter, first select the retaining position with the pointer scale around the median resistor according to the mark or color ring nominal value, connect the two pens short and adjust the pen to zero, so that the stylus is immediately at both ends of the measured element. The readout number multiplied by the blocking multiple is the actual resistance value, but the following points should be noted in the actual detection.

1.2. Shift has to be zero.

In the resistive detection, shift must be zero, especially Rx1 shift offset is larger, error increases, so shift must be re-zero. In the use of low-barrier detection connectors and components resistance, the two pens to each end of the element-must be good contact, otherwise by the contact resistance caused by the measurement error is very large.

1.3. The selection principle of the retaining position.

The selection of the multimeter retaining position, so that the needle finger around the median resistor is better, -is the best choice than the nominal value of a shift lower than the retaining position is most appropriate. For example, it is better to select R × 100 gear to measure a 1 000-ohm voltage.

1.4 effect of human resistance

To prevent the shunt effect of human resistance (about several hundred to several megawatts), do not touch the resistance lead and the metal part of the stylus when testing the resistor (refer to the high resistance resistor).

1.5. One end of the resistor should be soldered under the resistor measurement.

In order to accurately measure the actual resistance value of the resistor on the circuit, one end of the resistor must be welded to avoid being affected by the bypass diversion of other components in parallel to the resistor. In particular, the in-situ measurement of the upper and lower bias resistors in transistor-based circuits is greatly affected by the junction resistance of transistors.

1.6. The method of analyzing the measured resistance value.

(1). When the difference between the measured resistance value and the nominal value is less than + 10%, the normal use is generally not affected. It should be noted that there is still an error of + 2.5% in the multimeter blocking.

(2). If the difference between the measured resistance value and the nominal resistance value is greater than + 10%, the error of the resistance is large or has deteriorated.

(3). If the resistance of the resistor is measured to be infinite, the resistor is damaged on the open circuit.