What are the broad categories of multimeter failure methods?
Multimeters can be used to measure not only the resistance of the object being measured, AC and DC voltages but also DC voltages. Even some multimeters can measure the main parameters of transistors and the capacitance of capacitors. Fully master the use of multimeter is one of the most basic skills of electronic technology. Common multimeters are pointer multimeter and digital multimeter. Pointer multimeter is a multi-functional measuring instrument with a head as the core component, and the measured value is read by the pointer of the head. Digital multimeter measurement value by the liquid crystal display directly in the form of digital display, easy to read, some also with voice prompts. Multimeter is a common head, set of voltmeter, ammeter and ohmmeter in one instrument. Multimeter failure appears to be multi-factorial, and encounter problems with the randomness of large, not too much regularity to follow, repair is difficult. Positive editor will work for many years in the actual accumulation of some repair experience collated for your reference. Fluke multimeter troubleshooting methods can be broadly divided into the following categories:
(1) Measure the voltage method to measure the key points of the operating voltage is normal, you can quickly find out the failure point. Such as measuring the working voltage of the A/D converter, the reference voltage.
(2) feeling method by virtue of the senses directly to the cause of the failure to make a judgement, through the appearance of the inspection, can be found, such as broken wires, de-welding, short-circuiting lap, fuse tube broken, burnt components, mechanical damage, copper foil on the printed circuit warping and fracture, etc.; can be touched out of the battery, resistors, transistors, integrated blocks of the temperature rise, you can refer to the circuit diagrams to find out the reasons for the temperature rise abnormalities. In addition, the hand can also check whether the components are loose, whether the integrated circuit foot tube is inserted firmly, whether the changeover switch cassette; can hear and smell the sound, odour.
(3) Disconnect the suspicious part from the whole machine or unit circuit disconnect, if the fault disappears, said the fault in the disconnected circuit. This method is mainly suitable for the existence of short-circuit circuit.
(4) short-circuit method in the previously mentioned method of checking the A/D converter are generally used in the short-circuit method, this method is used in the repair of weak and microelectronic instruments.
(5) Measurement of components when the fault has been narrowed down to a certain place or a few components, can be measured online or offline. If necessary, replace the components with good ones, if the fault disappears, it means that the components are bad.
(6) Interference method using the human body induced voltage as an interference signal, observe the changes in the liquid crystal display, often used to check the input circuit and display part is intact.
