General instruments and meters are within the scope of precision instruments, especially for metering purposes, in order to ensure measurement accuracy, must be regularly overhauled, then share with you today the most common ways of maintenance.
1. The observation method makes use of sight, smell and touch. In some cases, the damaged components will discolor, blistering, or burn spots; burned devices will produce some special odors; short-circuited chips will become hot; visible or unwelded areas can also be observed with the naked eye. .
2. The replacement method requires two instruments of the same type or sufficient spare parts. Replace a good spare with the same component on the faulty machine and see if the fault is eliminated. The comparison method requires two instruments of the same type, and one is in normal operation. Use this method also has the necessary equipment, for example, multimeter, oscilloscope and so on. According to the nature of comparison, there are voltage comparison, waveform comparison, static impedance comparison, output comparison, and current comparison.
The specific method is: let the faulty meter and the normal meter operate under the same conditions, and then detect the signals of some points and then compare the measured two signals. If they are different, you can conclude that the fault is out here. This method requires maintenance personnel with considerable knowledge and skills.
3. The comparison method requires two instruments of the same type, and one is in normal operation. Use this method also has the necessary equipment, for example, multimeter, oscilloscope and so on. According to the nature of comparison, there are voltage comparison, waveform comparison, static impedance comparison, output comparison, and current comparison.
The specific method is: let the faulty meter and the normal meter operate under the same conditions, and then detect the signals of some points and then compare the measured two signals. If they are different, you can conclude that the fault is out here. This method requires maintenance personnel with considerable knowledge and skills.
4. Exclusion method The so-called exclusion method is to determine the cause of the fault by inserting and removing some plug-in boards and devices. When the instrument returns to normal after removing a certain board or device, it indicates that the failure occurred.
5, temperature rise and fall Sometimes, the instrument work for a long time, or in the summer when the working environment temperature is high, there will be failure, shutdown check is normal, stop for a period of time and then boot again and normal, after a while there is a failure. This phenomenon is due to the poor performance of individual ICs or components, and the high temperature characteristic parameters do not meet the requirements of the specifications. In order to find out the reason why the metal processing network, you can use the heating and cooling method.
The so-called cooling, that is, in the event of a failure, the use of cotton fiber will be wiped in place of possible failure of the alcohol to make it cool, observe whether the failure is eliminated. The so-called warming is artificially raising the temperature of the environment, such as using a soldering iron near the point of doubt (note that the temperature must not rise too high to damage the normal device) to see if the fault appears.
6, knocking method often encounter the phenomenon of good or bad instrument operation, the vast majority of this phenomenon is due to poor contact or welding caused. For this situation, tapping and hand pressure can be used.
The so-called "knocking" is to tap the board or component with a small rubber mallet or other knocker on the part that may be faulty to see if it will cause an error or stop failure. The so-called "hand pressure" is when the fault occurs, after the power is turned off, the plugged parts and the plug and the base are again pressed firmly by hand, and if the power supply is turned on, it will eliminate the fault. If it is found that knocking the case is normal, then when the beat is not normal, it is best to re-insert all joints and try again, if the brain is unsuccessful SOOQ. CN copyright, had to find another way.
7, riding method
The riding method is also called parallel method. Place a good IC chip on the chip to be inspected, or connect good components (resistance capacitors, diodes, transistors, etc.) in parallel with the components to be inspected to maintain good contact if the fault is caused by an open circuit inside the device or For poor contact and other reasons, this method can be ruled out.
8, the state adjustment method In general, before the failure is not determined, do not touch the components in the circuit, especially the adjustable device is even more so, for example, potentiometers. However, if multiple reference measures are taken beforehand (for example, position marks or voltage values ​​or resistance values ​​are measured before being touched), they are allowed to act if necessary. Maybe after some change, the fault will be eliminated.
9. Capacitance bypass method When a circuit produces strange phenomena, such as when the display is chaotic, a capacitor bypass method can be used to determine the part of the circuit that is probably faulty.
10, isolation method Fault isolation method does not require the same type of equipment or spare parts for comparison, and safe and reliable. According to the fault detection flow chart, segmentation and enveloping gradually narrow down the fault search range, together with signal comparison, component exchange and other methods, generally the fault will be found quickly.
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