For instrumenti takvi as multimetri, there are sever methods of fault diagnosis.
1. Udaraljke ruka tlak metoda
It is common to encounter the phenomenon of good and bad operation of the instrument. Most of this phenomenon is caused by poor contact or virtual soldering. For this situation, tapping and hand pressure methods can be used. The tzv "knocking" is to gently tap the plug-in board or component with a small guber hammer or other knocking object on the part where the fault may occur to see if it will cause an error or shutdown. The tzv "hand pressure" means that when a fault occurs, turn off the power, press the plug and socket firmly with your hands again, and then turn it on again to see if the fault will be eliminiran. If you find that it normal to knock the casing once, but it is abnormal again when you knock it again, it again, it is best to to re-insert all the connectors firmly and try again. If it is not successful, you have to find another way.
2. Promatranje metoda
Use sight, smell, and touch. Ponekad, oštećene komponente will discolor, blister, or have burnt spots; spaljene komponente will produce some special smell; short-cuted chips will become hot; and welding or desoldering can also be observed with the naked eye. .
3. Elimination method
The tzv troubleshooting method is to determine the cause of the fault by unplugging and plugging in some plug-in boards and devices in the machine. When the instrument returns to normal after removing a certain plug-in board or device, it means that the fault occur there.
4. Supstitucija metoda
It is required to have two instruments of the same model or senoughicient spare parts. Replace a good spare part with the same component on the faulty machine to see if the fault is eliminirano.
5. Usporedba metoda
It is required to have two instruments of the same model and one of them is running normally. To use this method, you must also have the necessary equipment, such as a multimeter, osciloskop, etc. Accord the nature of comparison, there are voltage comparison, waveform comparison, static impedance comparison, output result comparison, current comparison, comparison, current comparison, etc. The specific metoda is: let the neispravan instrument and the normal instrument run under the same conditions, then detect the signals at some points and compare the two measured signals. If there are differences, you can conclude that the fault lies here. This method requires maintenance personnel to have considerable knowledge and skills. Ten techniques for fault diagnosis of instruments such as multimetri
6. Grijanje i hlađenje metoda
Sometimes, the instrument will malfunction after working for a long time, or when the working environment temperature is high in summer. It will turn off and check if it is normal, then it will be normal again after stopping for a while, and then it will malfunction again after a while. This phenomenon is caused by the poor performance of individual ICs or components and the failure of high-temperature characteristic parameters to meet the index requirements. In order to find out the cause of the fault, the temperature rising and cooling method can be used. The so-called cooling means that when a fault occurs, use cotton fiber to wipe anhydrous alcohol on the parts where the fault may occur to cool it down and observe whether the fault is eliminated. The so-called heating refers to artificially raising the ambient temperature, such as using a soldering iron close to the suspected part (be careful not to raise the temperature too high to damage normal components) to see if a fault occurs.
7. Shoulder riding method
The shoulder riding metoda is also called the parallel metoda. Place a good IC chip on the chip to be inspected, or connect good components (otpornici, kondenzatori, diode, tranzistori, itd.) in parallel with the components to be inspected and maintain good contact. If the fault is caused by an open circuit or internal circuit within the device, Uzroci such as exposure to **can be eliminated by this method.
8. Kondenzator premosnica metoda
When a certain circuit proizvodi strange phenomena, such as a messy display, the capacitor bypass method can be used to determine the likely faulty circuit part. Connect the capacitor across the power supply and ground terminals of the IC; connect the transistor circuit across the base input terminal or collector out terminal to observe the impact on the fault phenomenon. If the capacitor bypass input terminal is invalid and the fault disappears when its out out terminal is zaobiđeno, it is determined that the fault occurs in this circuit.
9. Država prilagodba metoda
Općenito speaking, before the fault is determined, do not touch the components in the circuit casually, especial adjustable components, such as potenciometers. Međutim, if re-reference measures are taken in advance (for example, marking the position or measure the voltage or resistance value before touching), touching is still allowed when Necessary. Maybe after a change sometimes the glitch will go away.
10. Isolation Law
The fault isolation method does not require the same model of equipment or spare parts for comparison, and is safe and reliable. According the the fault detection flow chart, segmentation and encirclement postupno narrow the fault search scope, and then cocollaborate with methods such as signal comparison and component exchange, and the fault will general be found fast.
