Electrical equipment troubleshooting, open circuit, short circuit, parallel inspection method - Database & Sql Blog Articles

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The open circuit method, also known as the open circuit method or the split test method, is to disconnect the suspicious part from the whole circuit or unit so that it does not affect the normal operation of other parts, and see if the fault phenomenon disappears. If it disappears, it is generally said that the cause of the fault is at the circuit being cut.

Some electrical circuits are more complicated, involving more components, and thus many factors are affected; some closed-loop circuits, such as logic control circuits, are formed by connecting a plurality of unit circuits end-to-end, and thus are mutually restrained. When such a circuit fails, it is more convenient to use the segmentation method for detection. For example, for power failures with multiple loads, the "open circuit" method can be used to separate the suspected components, unit circuits, and power supply branches to determine their response to the fault phenomenon or to detect whether the function is normal or not. The location and cause of the fault can be quickly determined.

The short-circuit check method uses a short-circuit clamp (DC short-circuit) or a clamp (AC short-circuit) with a capacitor to short-circuit a certain part or a certain component of the circuit, and judge the fault from changes in image, sound and voltage. The identification of faults such as noise, interference, ripple, and self-oscillation is simple and rapid. For example, the maintenance TV set can be connected to the SAWF with a 100pF capacitor clamp. If the picture appears, the SAWF is damaged. Another example is the use of a capacitor clamp to short-circuit a certain circuit input terminal to ground, and the interference disappears. This indicates that the fault is present before this level, and after checking in sequence, the fault can be quickly found. The size of the capacitor used in the short circuit method increases or decreases depending on the operating frequency of the circuit.

The parallel detection method is to judge the fault by using components with good performance, similar specifications or adjustable components to be connected in parallel to the suspected components. Since this method does not require desoldering circuit components, it can be used preferentially. For example, when repairing the color TV with a multimeter, it is difficult to judge the open circuit of the small capacitor, and the failure can be judged by the parallel capacitance method. If the fault disappears after paralleling, it means that the suspected capacitor is indeed damaged; if the parallel is invalid or the acoustic map is worse, it is suspected to be eliminated. For loop capacitance, variable capacitors can be used in parallel to determine the required capacity. As for the resistance deterioration and open circuit failure, the resistance parallel method can be used for inspection. If the potentiometer is used in parallel, the optimum resistance value can be determined by adjustment. For components that are difficult to remove soldering inspection, parallel inspection can also be used.

In summary, the three inspection methods of open circuit, short circuit and parallel have their own advantages, and they play a role in checking short circuit, open circuit and failure.