5 ways to find faults with multimeters
⒈ feeling method
Use the senses to directly judge the cause of the failure. Through visual inspection, you can find such as disconnection, desoldering, short circuit, broken fuse tube, burnt components, mechanical damage, copper foil lifting and fracture on the printed circuit, etc. ; You can touch the temperature rise of the battery, resistors, transistors, and integrated blocks, and you can refer to the circuit diagram to find out the reason for the abnormal temperature rise. In addition, by hand, you can also check whether the components are loose, whether the integrated circuit pins are firmly inserted, and whether the transfer switch is stuck; you can hear and smell whether there are abnormal sounds and odors.
⒉ voltage measurement method
Measuring whether the working voltage of each key point is normal can quickly find out the fault point. Such as measuring the working voltage and reference voltage of the A/D converter.
⒊Short circuit method
In the method of checking the A/D converter mentioned above, the short-circuit method is generally used. This method is often used when repairing weak and micro-electric instruments.
⒋ circuit breaking method
Disconnect the suspicious part from the whole machine or unit circuit. If the fault disappears, it means that the fault is in the disconnected circuit. This method is mainly suitable for the situation where there is a short circuit in the circuit.
5. Measuring element method
When the fault has been narrowed down to one or a few components, it can be measured online or offline. If necessary, replace it with a good one. If the fault disappears, the component is broken.
Introduction to the accuracy of digital multimeters
The accuracy of a digital multimeter is a combination of systematic and random errors in the measurement results. It indicates the degree of agreement between the measured value and the true value, and also reflects the size of the measurement error. Generally speaking, the higher the accuracy, the smaller the measurement error, and vice versa.
Digital multimeters are far more accurate than analog analog multimeters. The accuracy of the multimeter is a very important indicator. It reflects the quality and process capability of the multimeter. It is difficult for a multimeter with poor accuracy to express the real value, which may easily cause misjudgment in measurement.
