See the following for the failure phenomenon, causes and solutions of the sound reinforcement system.
（1） : The sound reinforcement system plays without sound
The power plug of one or several of the audio equipment connected in series is not properly plugged. Solution: Check the power wiring board to make the socket contact well.
 
（2） : The sound reinforcement system sometimes makes a "click" sound, especially in the process of playing music.
(1) The connecting line between the equipment of the sound reinforcement system has the phenomenon of faulty soldering. When there is music signal, the faulty solder joint makes the sound signal intermittent. Solution:
(2) The wiring of each channel equipment must be thoroughly checked, and it is better to re-weld each connection point;
(3) If the connection welding points are thoroughly checked, there is still "clicking" phenomenon, which may be that the connection wire is broken. Check each wire with a multimeter and replace the cable with broken wire inside.
 
（3） : When the sound reinforcement system is silent, the communication sound is serious
1. The connection shield wire of each channel equipment has poor contact or faulty soldering. Solution: carefully check the shield wire between each equipment and try to use welding.
2. The equipment with three-pin power plug is connected to the two-wire input socket, and the two-level live wire and the neutral wire are inversely connected. Solution: the two-wire input socket, the neutral wire and the live wire must be reversed. Generally, the left leg of the socket is the neutral wire, and the right leg is the live wire. The power plug board shall be equipped with three pins, and the pins at the middle and upper parts shall be grounded to ensure power safety.
3. Some audio equipment uses two-pin plug, but some equipment must use three-pin plug, otherwise there may be AC induction phenomenon when connecting between them, leading to the solution of AC sound: reverse the power plug of the audio equipment with two-pin plug.
 
（4） : When the audio system and the lighting system are running at the same time, the AC noise of the audio system is very loud. When the lighting system is turned off, the AC noise of the audio system is not heard when the audio system is running. The sound system and the lighting system share the same single-phase power. The thyristor of the lighting system has a large working current and is AC pulse type. It is directly coupled to the input end of the expansion device through the power lead, thus generating a large AC sound solution:
(1) Sound system and lighting system are powered independently;
(2) The audio system is powered by an isolation transformer whose power should be greater than that of the audio system;
 
（5） : In the process of sound reinforcement, a group of speakers or two groups of speakers at the left and right channel entrances suddenly become silent;
In general, the power amplifier is damaged due to overload or the speaker is burnt due to too large sound power. Solution:
(1) Replace the power amplifier or speaker;
(2) When replacing the high-power transistor with a special-shaped pair to repair the power amplifier, we must pay attention to the occurrence of this situation, which is caused by overload. During tuning, we should pay high attention to the operation problems. In order to protect the power amplifier or speaker, the sound reinforcement system can consider adding a limiter;
 
（6） In the karaoke hall, the singer's singing and the music accompaniment played are separated and not integrated.
1. When the left and right channels of the sound source enter the mixing station, the audio and image adjusting buttons on the corresponding channels are placed in disorder, resulting in audio and image confusion. Solution: correct the adjustment of the audio and image adjusting buttons of the corresponding channels, so that the output signal of the mixing station retains the audio and image of the original sound source;
2. The room equalizer only compensates for the sound of music, or the adjustment of the room equalization curve of the room equalizer is unreasonable. Solution: readjust the room equalization compensation curve;
 
（7） : The effect processing of singing voice is not added
1. The singing sound does not enter the effect machine. Solution: turn on the corresponding auxiliary knob on the singing channel, turn on the auxiliary knob sent by the auxiliary bus, and observe the input signal indicator of the effect machine to see if there is an input signal.
2. The effect sound sent by the effect machine is not programmed into the left and right channel bus or the marshalling bus solution: press the button programmed into the corresponding bus.
3. The effect machine is damaged. Solution: replace the effect machine.
 
（8） : The effect in the singing sound is small and not full enough
It may only use the single-channel effect sound of the effect machine, or it is not connected according to the two-in-two-out method of the effect machine: generally, the effect machine has left and right channel inputs and left and right channel outputs. Try to connect in this way.
 
（9） : The sound source plays, and the loudspeaker of the sound reinforcement system is silent
1. The sound source has no output sound signal, or the output plug socket of the sound source equipment has short circuit or open circuit.
Solution: repair the sound source equipment or replace the sound source equipment. Carefully check the sound source in the wiring and plug socket to eliminate short circuit or open circuit.
2. There is an open circuit or short circuit in the connecting wire between the equipment. Solution: carefully check the connection condition of the equipment wiring and plugs and sockets, and eliminate faulty soldering, desoldering and short circuit.
3. One or several power switches of the serial equipment are not connected, and the acoustic signal is interrupted. Solution: connect the power of the audio equipment.
4. Solution to the misplacement of the sound source button in the input channel of the mixer: correctly place the sound source switch button.
 
（10） : Silent signal when the microphone is inserted into the mixer
The microphone switch is in poor contact, the microphone switch is not turned on, or the microphone is damaged Solution: check the microphone connecting line, connect the microphone switch or replace the microphone.
 
（11） : Hand-held stage wired microphone, with a slight swing action, the sound reinforcement box makes a "click" sound.
1. The microphone switch has poor contact. Solution: replace the microphone switch or re-weld the switch wiring.
2. The microphone terminal is disconnected, or the shielded wire is touching the signal wire Solution: remove the XLR plug base, weld the disconnected wire firmly, separate the shielded wire from the signal wire clearly and weld firmly.
 
（12） : When a single microphone is connected, the volume is higher. When the two microphones are connected, the volume decreases, and the signal input from the two microphones to the mixer is inverted.
Solution: If each input of the mixing table is equipped with a phase inversion key, press one of the two microphone inputs. If each input of the mixing table is not equipped with a phase inversion key, weld one of the microphone signal lines, and then weld them firmly.
 
（13） : After the wireless microphone is turned on, there is no sound when speaking at the microphone
1. The battery on the wireless microphone is insufficient. Solution: replace the battery with a new one.
2. The tuner volume is not turned on Solution: Turn on the tuner volume switch and exceed 3/5.
3. The receiving antenna angle of the tuner is not adjusted properly. Solution: change the receiving angle of the tuner antenna to avoid dead angle in the host activity area.
 
（14） : The left and right channels of the sound source have output, and there is no sound signal output after entering the mixer.
1. The constant value attenuation key of the corresponding input channel on the mixer is pressed. Solution: pop up the constant value attenuation key of the corresponding channel on the mixer.
2. Put the gain adjustment on the corresponding channel at the lowest position. Solution: turn on the gain adjustment on the corresponding channel and put it at the 2/3 position.
3. The placement of the audio-image adjusting knob on the corresponding channel is opposite to the input left and right channel signals. Solution: the placement of the audio-image adjusting knob on the corresponding channel is consistent with the input left and right channel signals.
4. The plug of the input mixer is in poor contact or disconnected. Solution: check the plug at the input end and weld it firmly.
5. Poor contact or desoldering at the output end of the mixer. Solution: check the output plug of the mixer, connect it correctly and weld it firmly.
6. The input signal is not programmed into the corresponding output bus. Solution: press the corresponding output programming button.
 
（15） : The left and right channel speakers are not balanced
1. The sensitivity of the left and right channel speakers is different. Solution: adjust the output levels of the left and right channels to make the speaker sound nearly consistent.
2. The output power signal of the left and right channels is not balanced. Solution: adjust the input power level of the equipment of each channel to approximately the same indication.
 
（16） : One of the tweeters (tweeters) of the left and right channel speakers has no tweeter, and the tweeters of this channel speakers are overloaded and burned.
Solution: Switch the two input signals of the power amplifier. If the tweeter of the speaker still has no tweeter, it means that the tweeter is burned out and the voice coil should be replaced
 
（17） : The left and right channel speakers are split. The sound of each channel speaker is uneven. The frequency dividing point of the two-channel electronic frequency divider is not adjusted properly.
Solution: According to the use of frequency divider, carefully adjust the crossover frequency points at the high and low ends