How to detect the failure of a digital multimeter - Database & Sql Blog Articles

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The multimeter can be used not only to measure the resistance of the object being measured, but also to measure the DC voltage. Even some multimeters can measure the main parameters of the transistor and the capacitance of the capacitor. Fully mastering the use of the multimeter is one of the most basic skills of electronic technology. Common multimeters have pointer multimeters and digital multimeters. The pointer multimeter is a multi-function measuring instrument with a head as the core component, and the measured value is read by the pointer of the meter. The measured value of the digital multimeter is displayed directly by the liquid crystal display in digital form, which is convenient to read, and some also have a voice prompt function. A multimeter is a meter that shares a meter head, a voltmeter, an ammeter, and an ohmmeter. The failure of the multimeter is multifactorial, and the randomness of the problem is large. There are not many rules to follow, and the repair is difficult. The frontal Xiaobian compiled some of the repair experience accumulated in the actual work for many years for your reference. The troubleshooting methods for Fluke multimeters can be roughly divided into the following categories:
(1) The measuring voltage method measures whether the working voltage of each key point is normal, and can find the fault point faster. Such as measuring the operating voltage, reference voltage of the A / D converter.
(2) The sensory method makes judgments directly on the cause of the fault by means of the senses. Through visual inspection, it can be found that such as wire breakage, desoldering, wire short circuit, fuse tube break, burnt component, mechanical damage, copper foil on printed circuit. Lifting and breaking, etc.; you can touch the temperature rise of the battery, resistor, transistor, and integrated block. Refer to the circuit diagram to find out the cause of abnormal temperature rise. In addition, the hand can also check whether the component is loose, whether the integrated circuit foot tube is firmly inserted, whether the transfer switch is jammed, and the sound and odor can be heard and smelled.
(3) The open circuit method disconnects the suspicious part from the whole machine or unit circuit. If the fault disappears, it indicates that the fault is in the disconnected circuit. This method is mainly suitable for the case where the circuit is short-circuited.
(4) Short-circuit method In the above-mentioned inspection A/D converter method, the short-circuit method is generally used, and this method is used more frequently in repairing weak current and micro-electrical instruments.
(5) Measuring component method When the fault has been reduced to somewhere or several components, it can be measured online or offline. If necessary, replace it with a good component. If the fault disappears, the component is broken.
(6) The interference method uses the human body induced voltage as an interference signal to observe the change of the liquid crystal display, and is often used to check whether the input circuit and the display portion are intact.