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Description of the nine major instrumentation fault diagnosis methods

1. Isolation method
The isolation method refers to the fault detection flow chart, segmentation and enveloping to gradually narrow down the fault search range, and then cooperate with signal comparison and component exchange to find out the cause of the fault.
2. Observation method
When the instrument fails, people can use the visual, olfactory, tactile and other methods to observe the instrument and see which position it is faulty. If some instruments fail, the internal damaged components may appear discolored, blistering or burnt spots; the burnt device will produce some special odors, such as burnt smell; short-circuited chips will be hot And the place where the welding or desoldering can be observed with the naked eye.
3. Knocking method
People sometimes encounter unstable operation of the instrument, which is usually caused by poor contact or solder joints. In this case, one can use the tapping method, that is, tap the board or part with a small rubber hammer or other tapping object on the part that may cause the fault to see if it will cause an error or a shutdown failure.
4. Replacement method
When the instrument fails, if there are two instruments of the same model or there are enough spare parts. Then people can replace a good spare component with the same component on the faulty machine to see if the fault is eliminated. If the fault is eliminated, it means a fault caused by the replaced component.
5. Exclusion
The so-called elimination method is to determine the cause of the fault by plugging in some plug-in boards and devices inside the instrument. If the instrument returns to normal after removing a board or device, the cause of the malfunction is here.
6. Lifting temperature method
If the instrument works continuously for a long time, it is more likely to malfunction. This may be because the internal temperature of the instrument rises due to long-term work, which affects the normal operation of the instrument. At this point, you can turn off the instrument for a period of time, wait a while and then turn it on to see if the instrument can work normally.
7. Capacitor bypass
When a circuit produces a strange phenomenon, such as a display disorder, the capacitor bypass method can be used to detect which part of the faulty circuit.
The above is the fault detection method of the nine instruments introduced by Xiaobian. If the instrument fails to detect the cause of the fault after repeated testing, it is recommended that the company purchase a new instrument.
8. Riding the shoulder method
The shoulder method is also called parallel method, that is, a good IC chip is placed on the chip to be inspected, or good components (resistance capacitors, diodes, transistors, etc.) are connected in parallel with the components to be inspected to maintain good contact. . This detection method can detect the cause of malfunction such as open circuit or poor contact inside the device.
9. Comparison method
The comparison method refers to the use of two instruments of the same type, one of which is in normal operation. Then let the faulty meter and the normal meter run under the same conditions, and then detect the signals of some points, such as voltage, waveform, static resistance, etc., and then compare the two groups of signals measured. If any group of data is different, then It can be concluded that the fault is here.

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