Ten common fault judgment methods for industrial instruments

Instrument failure is a problem that we often encounter in our work, so what are the good ways to judge the failure and find out the problem? Here are 10 methods for analyzing and judging industrial instrument faults, summarizing years of instrument maintenance experience, hoping to be helpful to everyone. The direct observation method does not use any test equipment, but observes and finds faults through human senses. The visual inspection method is divided into two types: visual inspection and startup inspection. The visual inspection mainly includes: ①Whether the instrument shell and dial glass are in good condition, whether the pointer is deformed or colliding with the dial, whether the assembly fasteners are firm, whether the position of each switch knob is correct, whether the movable part rotates flexibly, and whether the adjustment position Whether there is any obvious change; ② Whether the connection is disconnected, whether the connectors are connected normally, whether the spring on the circuit board socket is insufficiently elastic and has poor contact. Tighten; ③ Whether the contacts of the relays and contactors are dislocated, stuck, oxidized, burnt and stuck to death, etc.; ④ Whether the power fuse is blown, whether the electronic tube is broken or leaking (after the leak, the inner wall of the tube is attached with a layer of white powder), damage, whether the paint of the transistor shell is discolored, broken, whether the resistance is burnt, whether the coil is broken, whether the capacitor shell is swollen, leaking, or bursting; Whether the solder joints of the components are in good condition, and whether there are virtual soldering, missing soldering, or de-soldering; The power-on inspection mainly includes: ① whether the power indicator light, each electronic tube and other light-emitting components in the machine are energized and lit; ② whether there is high-voltage ignition, discharge, or smoke in the machine; Collision sound; ④Is the temperature rise of transformers, motors, power amplifier tubes and other heat-prone components and resistors, integrated blocks normal, whether there is hot hand phenomenon; ⑤Is ​​there any special smell in the machine, such as transformer resistance, etc. The smell of burnt, the oscilloscope tube high-voltage leakage and ignition caused by the ionization of the air; ⑥ Whether the mechanical transmission part is running normally, whether there is bad gear meshing, stuck and severe wear, slip deformation, transmission failure, etc. Phenomenon. Visual inspection must be very careful and careful, and should not be careless and impatient. When checking the components and connections, you can only shake them gently, and do not use too much force to prevent breaking the components, connections and the copper foil of the printed board. Do not leave the power switch with your hands when turning on the power and check the power. If any abnormality is found, it should be turned off in time. Pay special attention to personal safety and absolutely avoid touching live equipment with both hands at the same time. The large-capacity filter capacitors in the power supply circuit are charged in the circuit to prevent electric shock. The investigation method is a method of analyzing and judging the cause of the failure through the investigation and understanding of the failure phenomenon and its production and development process. Generally, there are the following aspects: 1. The use situation before the fault occurs and whether there are any signs; 2. Whether there is fire, smoke, abnormal smell, etc. when the fault occurs; 3. Changes in the power supply voltage; 4. Overheating, lightning, humidity, Collision and other external conditions; ⑤ Whether there is interference by strong external electric fields and magnetic fields; ⑥ Whether there is improper use or misoperation; ⑦ Failures that occur under normal use or after repairing and replacing components; ⑧ Before What failures and repairs have occurred.