Ten Easy Methods to Diagnose Faults in Instruments, Meters, and Multimeters
1. Exclusion method
The so-called troubleshooting method is to determine the cause of a malfunction by plugging and unplugging some plug-in boards and components inside the machine. When a certain plug-in board or component is unplugged and the instrument returns to normal, it indicates where the fault occurred.
2. Knocking hand pressure method
3. Observation method
Utilize visual, olfactory, and tactile senses. Sometimes, damaged components may discolor, blister, or show burnt spots; Burnt devices may produce some special odors; Short circuited chips will heat up; Virtual or detached solder joints can also be observed with the naked eye.
4. State adjustment method
Generally speaking, before the fault is determined, do not touch the components in the circuit casually, especially adjustable devices such as potentiometers. However, if multiple reference measures are taken in advance (such as marking the position or measuring the voltage or resistance value before triggering), triggering is still allowed if necessary. Perhaps sometimes the malfunction will be eliminated after the change.
5. Comparative method
Two instruments of the same model are required, and one of them is operating normally. To use this method, it is necessary to have necessary equipment, such as a multimeter, oscilloscope, etc. 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 operate the faulty instrument under the same conditions as the normal instrument, then detect signals at certain points and compare the two sets of signals. If there are differences, it can be concluded that the fault is located here. This method requires maintenance personnel to have considerable knowledge and skills.
6. Isolation method
Fault isolation method does not require the same model
7. Substitution method
Require two instruments of the same model or sufficient spare parts. Replace a good spare part with the same component on the faulty machine to see if the fault has been eliminated.
8. Temperature rise and fall method
9. Shoulder riding technique
The shoulder riding method is also known as the parallel method. Place a good IC chip on top of the chip to be inspected, or connect good components (resistors, capacitors, diodes, transistors, etc.) in parallel with the component to be inspected and maintain good contact. If the fault is caused by internal open circuits or contact * *, this method can be used to eliminate it.
10. Capacitor bypass method
When a certain circuit experiences strange phenomena, such as display confusion, the capacitor bypass method can be used to determine the approximate faulty part of the circuit. Connect the capacitor across the power and ground terminals of the IC; Cross connect the transistor circuit at the base input or collector output and observe the impact on the fault phenomenon. If the fault disappears when the capacitor bypass input terminal is invalid and bypasses its output terminal, it is determined that the fault is present in this safe circuit.
