Circuit faults are classified one by one, and there are those common circuit faults

1.First of all, correct the mistake of the question itself:

If only one bulb is broken, two bulbs in series, and neither of the closing switches is lit, then the bad bulb cannot be a short circuit, but only an open circuit!

Therefore, the following is only the case of open circuit.

In addition, the so-called voltmeter measurement and ammeter measurement refer to the two pins of the meter needle at the two ends of L1 and L2 respectively.

2.If L1 is open, use a voltmeter to measure: there is a voltage on L1, and the voltage value is the power supply voltage; There is no voltage on L2.

3.If L2 is open, use a voltmeter to measure: there is no voltage on L1; There is a voltage on L2, and the voltage value is the supply voltage.

4.If L1 is open, use the ammeter to measure: when L1 is measured, the L2 light is on, because the internal resistance of the ammeter is 0, the open circuit of L1 is shorted, and the ammeter reads the power supply voltage (power supply internal resistance + L2 resistance); When measuring L2, the current is 0.

5.If L2 is open, use an ammeter to measure: when L1 is measured, the current is 0; When measuring L2, the L1 light is on, because the internal resistance of the ammeter is 0, the open circuit of L1 is shorted, and the ammeter reads the power supply voltage (power supply internal resistance + L1 resistance).

Landlord, there is a problem with your problem, two bulbs in series, if the voltage is normal (within the allowable voltage range of the bulb, one bulb is short-circuited, then there must be a bulb on, why are both not lit (unless the voltage does not reach the limit of the bulb at all); The problem of open circuit, that open circuit, that one has voltage; If you use an ammeter, the one that measures the open circuit will have a current (but pay attention to the range).

If it is only a bulb problem, then it cannot be a short circuit, it can only be an open circuit, measure the voltage at both ends of L1 and L2 respectively, and open the circuit if there is a voltage.

1. Circuit breaking: that is, the line is short, the lamp holder, the opening and closing of the chatter, the hanging box is broken, the fuse is blown or the incoming line is broken, etc. It will cause the electrical appliances to be unable to work with electricity;

2. Short Zen brings defeat: that is, the electricity takes a shortcut, and the two wires in the socket collide. The short circuit will blow the fuse and cut off the power of the entire lighting circuit, and in severe cases, it will burn the line and cause a disaster;

3. Overload: that is, it cannot bear the load, and the total power of the electrical appliances in the circuit is too large or the power of a single electrical appliance is too large;

4. Poor contact: that is, the contact is not real, the contact of the hanging box is poor, the fuse is poor, the contact is poor, the contact is poor, etc. It will make the lights flicker on and off, and the electrical appliances cannot work continuously;

5. Confusion on the lower road: The lines used are connected together in a chaotic manner.

A circuit fault is a malfunction of a guide wire or electronic device that loses its normal working condition. It is usually manifested as the circuit cannot be opened, there is no output, or the output is abnormal.

1.Cause of circuit failure

Damage to circuit components, such as coil burnout, capacitor leakage, integrated circuit chip burnout, etc.

The welding brigade is not well connected, resulting in unstable circuit or poor contact.

Interference from external factors, such as light, temperature, humidity and other factors, causes damage to electronic components.

Power supply problems, such as power supply voltage too high or too low, power supply fluctuations, etc.

2.Classification of circuit faults

Open circuit fault: refers to the phenomenon that a circuit is broken in a certain part of the circuit, and the current cannot pass.

Short-circuit fault: refers to the phenomenon of short circuit between two electrodes in the circuit, and the current is too large to cause the system to not work normally.

Leakage fault: Leakage occurs in a circuit, causing the current to be too large for the device to function properly.

Overvoltage or undervoltage: A supply voltage that is too large or too small can lead to circuit failure.

3.How to troubleshoot circuit faults

Inspect the components to determine which part is damaged and replace the appropriate component.

Perform a soldering check to ensure the stability of the circuit and good contact.

Check the causes of interference from external factors, such as light, temperature, humidity, etc., and take timely measures to adjust.

Check for power supply issues, including whether the supply voltage is too large or too small, and the stability and reliability of the power supply.

4.Prevent circuit failures

Choose reliable components to improve the reliability of the device itself.

Develop a reasonable maintenance plan and regularly inspect and repair the equipment.

Pay attention to the equipment in a complete, stable and clean environment to reduce the interference of external factors on electronic components.

Use a stable power supply to avoid problems such as overvoltage or undervoltage.

Series Circuit FaultThe fault phenomenon of series circuit is generally summarized into two categories: open circuit (also made"Circuit breaking").All electrical appliances do not work, and the ammeter has no indication, only the voltmeter that collapses on both sides of the breakpoint has an indication, and the indication is close to (or equal to) the power supply voltage.

Short circuit. The part of the electrical appliances that are short-circuited does not work, and the ammeter has an indicator, the voltmeter connected to both ends of the short-circuited electrical appliances has no indicator, and the voltmeter connected to both ends of other electrical appliances has an indicator.

Common circuit faults are as follows:

1. Short circuit: A short circuit will blow the fuse of the lamp, and the lamp will burn out. In fact, it is made by the collision of two wires in the socket.

into the results. 2. Broken circuit: Broken circuit will cause all electrical appliances to fail to operate normally, that is, the circuit is short, and the circuit between the lamp holder, the switch and the line is broken.

Is the fuse broken or the line entering the house broken?

3. When installing the line, each route was not installed, the lower road was disordered, and all the lines were connected together.

4. Load: The total power of the electrical appliance is too large, and it has exceeded the range that the circuit can bear, and there will be a short circuit.

5. Poor contact: that is, the contact is not real, the contact of the hanging box is poor, the fuse contact is poor, the contact at the line joint is poor, etc. This.

It will make the lights flicker on and off, and the electrical appliances will not work continuously.

Electrician knowledge, plumbing knowledge sharing.

Main judgment methods:

Symptom "1: The electrical appliance does not work.

Diagnosis: (1) If the circuit in the question is a series circuit, see if other electrical appliances can work, if all electrical appliances can not work, it means that there may be an open circuit somewhere; If other appliances are still working, it means that the appliance has been short-circuited.

2) If the circuit in the question is a parallel circuit, if all the electrical appliances are not working, it means that the trunk circuit has been opened; If other electrical appliances are still working, it means that the branch where the electrical appliances are located is open.

Symptom "2: The number of voltage representations is zero.

Diagnosis: (1) The circuit is broken between the two binding posts of the voltmeter and the two poles of the power supply;

2) There is a short circuit between the two binding posts of the voltmeter.

Symptom "3: The number of current representations is zero.

Diagnosis: (1) There is an open circuit in the circuit where the ammeter is located and the circuit formed by the two poles of the power supply.

2) The resistance of the circuit where the ammeter is located is very large, resulting in the current being too small, and the pointer of the ammeter is almost immobile (if the voltmeter is connected in series in the circuit).

3) The ammeter is short-circuited.

Symptom "4: The ammeter is burned out.

Diagnosis: (1) The circuit where the ammeter is located directly forms a loop between the two poles of the power supply, that is, a short circuit occurs.

The wires between the voltmeters are short-circuited.

If the circuit in the question is a parallel circuit, if all the electrical appliances are not working, it means that the trunk circuit has been broken or the branch circuit has been shorted (supplemented).

Hello. The common faults of the friend circuit are as follows.

1) Break the circuit. That is, the line is short, the lamp holder, switch, hanging box is broken, the fuse is blown or the incoming wire is broken, etc. Breaking the circuit will cause the electrical appliances to be unable to work with electricity.

2) Short circuit. It's just that the electricity took a shortcut, and the two wires in the socket collided. The short circuit will blow the fuse and cut off the power of the entire lighting circuit, and in serious cases, it will burn the line and cause a disaster.

3) Overload. It is that it cannot withstand the conformity, the total power of the electrical appliances in the circuit is too large or the power of a single electrical appliance is too large. The resulting phenomena and consequences are the same as short circuits.

4) Poor contact.

That is, the contact is not real, the contact of the hanging box is poor, the fuse contact is poor, the contact at the line joint is poor, etc. This will make the lights flicker on and off, and the electrical appliances will not work continuously.

5) Lower road disorder: used.

The threads are all connected. Oh.

1.Direct observation: When a circuit fails, it is not necessary to immediately measure it with an instrument, but to look for possible abnormalities in the circuit with the naked eye. The direct observation method is divided into non-energized and energized detection.

The non-energizing test is to check whether the level and polarity of the power supply voltage meet the circuit requirements;

2.Multimeter detection, multimeter detection is mainly to check the static working point, in which the resistance value and DC working state in the power supply system, transistor, integrated block and line of the electronic circuit can be detected by the multimeter. Check whether the value is normal.

3.In a complex circuit, the signal tracing method can be used to insert a signal at the input end, and then observe the waveform and amplitude changes from the pre-amp to the post-amp or from the post-amp to the pre-amp through the oscilloscope, and finally see which stage is abnormal.

4.The comparison method is more intuitive, mainly by comparing the parameters of the suspected fault circuit with the same circuit in normal working state, finding out whether there is a value with a large parameter gap, and then analyzing the cause of the fault, and always judging the fault location.

5.The substitution method can be used for electronic circuits where the fault is not obvious, and when it is impossible to make an intuitive judgment or when the fault point is suspected.