Instrument maintenance has always been an indispensable part of electronic companies. Because only through it can the originally unqualified products be finally delivered. However, maintenance is also a complex part of electronics companies. Because it requires not only a lot of electronic knowledge, but also rich on-site experience. Let's discuss several commonly used methods
1.Percussive hand pressure method
It is often encountered that the instrument works well and sometimes fails, which is mostly caused by poor contact or faulty soldering. In this case, tapping and hand pressing methods can be used. The so-called "knocking" refers to gently tapping the plug-in board or component with a small rubber hammer or other knock to see if it can cause an error or shutdown fault at the location where the fault may occur. The so-called "hand pressing" means that when a fault occurs, after turning off the power supply, firmly press the inserted components, plugs, and seats again by hand, and then restart the machine to see if it will eliminate the fault. If it is found that knocking the casing is normal, and then knocking it again is abnormal, * Well, first plug in all the copper waterproof connectors JG-T-M firmly and try again. If the problem is not successful, you have to find another way.
2. Observation method
Utilize the senses of sight, smell, and touch. Sometimes, damaged components may discolor, blister, or show scorched spots; Burned devices can produce some special odors; Short circuited chips can burn; False soldering or desoldering can also be observed with the naked eye.
3. Exclusion method
The so-called troubleshooting method is a method of determining the cause of a fault by plugging and unplugging some plug-in boards and devices in the machine. When a certain plug-in board or device is unplugged and the instrument returns to normal, it indicates where the fault occurred.
4. Substitution method
Two instruments of the same model or sufficient spare parts are required. Replace a good spare part with the same component on the faulty machine to see if the fault has been eliminated.
5. Comparative method
It is required to have two instruments of the same model, and one of them is in normal operation. To use this method, it is necessary to have necessary equipment, such as a multimeter insulated multimeter, an oscilloscope oscilloscope, and so on. According to the nature of comparison, there are voltage comparison, waveform comparison, static impedance comparison, output result comparison, current comparison, etc. The specific method is to allow a faulty instrument and a normal instrument to operate under the same conditions, then detect signals at some points and compare the two groups of signals measured. If there are differences, it can be concluded that the fault is here. This method requires maintenance personnel to have considerable knowledge and skills.
6. Ascending and descending temperature method
Sometimes, the instrument works for a long time, or when the temperature of the working environment is high in summer, it will malfunction. The shutdown check is normal, the restart after a period of time is normal, and then the malfunction occurs again. This phenomenon is caused by poor performance of individual IC integrated circuits PI5V330SQ or components, and the high temperature characteristic parameters cannot meet the index requirements. In order to find out the cause of the fault, the temperature rise and fall method can be used. The so-called cooling refers to wiping anhydrous alcohol with cotton fiber on the likely fault area when a fault occurs, cooling it, and observing whether the fault has been eliminated. The so-called temperature rise refers to artificially raising the ambient temperature, such as placing an electric soldering iron close to a suspected location (be careful not to raise the temperature too high to damage normal devices) to see if a fault occurs.
7. Shoulder riding method
The shoulder riding method is also known as the parallel method. Install a good IC chip on the chip to be inspected, or connect good components (resistors, capacitors, diodes, transistors, etc.) in parallel with the component to be inspected, maintaining good contact. If the fault is caused by an internal open circuit or poor contact within the component, this method can be used to eliminate it.
8. Capacitance bypass method
When a certain circuit produces strange phenomena, such as display text confusion, the capacitance bypass method can be used to determine the likely faulty circuit part. Connect the capacitor across the power and ground terminals of the IC; Jump the transistor circuit at the base input terminal or the collector output terminal and observe the effect on the fault phenomenon. If the capacitor bypass input is invalid and the fault disappears when bypassing its output, it is determined that the fault occurs in this stage of the circuit.
9. State adjustment method
Generally speaking, before determining a fault, do not touch any components in the circuit, especially adjustable devices such as potentiometer grinding tools. However, if multiple reference measures are taken in advance (such as making position marks or measuring voltage or resistance values before touching), touching is still allowed when necessary. Perhaps the fault will sometimes be eliminated after the change.
10. Isolation method
The isolation method does not require comparison of equipment or spare parts of the same model, and is safe and reliable. According to the fault detection flow chart, the fault search scope is gradually reduced by dividing and surrounding, and then combined with signal comparison, component exchange and other methods, the fault will generally be found quickly.
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