Power amplifier circuit is a common channel in the sound system, but also in the whole high voltage, current, high temperature components, so the fault rate is high.

1. completely silent
Fault analysis: completely silent may be a power amplifier or power failure.
1. Left and right channel completely silent
Maintenance method: First check the power supply voltage of the power amplifier. If not, check whether the fuse in the power amplifier is blown and whether the power supply circuit is normal. If so, check whether the power amplifier output is open and whether the protection circuit operates. If the power amplifier output circuit is normal, check whether the DC working voltage of the tone control circuit and the preamplifier circuit is normal. If normal, the signal injection method can be used to check a channel.
2. Only one channel is completely silent
Maintenance method: First, connect the two-channel speakers to each other. If the original channel is normal after the exchange and the other channel is completely silent, it indicates that the speaker is faulty. If the fault persists after the swap, the power amplifier of the original channel may be faulty, and the DC voltage at the output end of the power amplifier of the channel should be measured to see if it is abnormal. If the measurement is abnormal, it indicates that the integrated power amplifier is very likely to be damaged. After checking the external circuit of the integrated circuit without abnormality, replace the integrated circuit; if it is normal, use the signal injection method to check the channel system.

2. noise big fault analysis:
The noise is mainly due to the leakage of coupling capacitors, changes in the performance of electrolytic capacitors, and poor contact of potentiometers. Maintenance method: alternative method can be used to check whether the filter capacitor of the whole machine is invalid, and then check whether the filter of DC working voltage of power amplifier front amplifier circuit and tone control circuit leaks electricity. For the failure of noise only when the potentiometer is rotated, the potentiometer can be cleaned first and replaced after it is invalid.

3. silent fault analysis:
Silent fault means that there is no audio signal sound, but there is current sound. The fault indicates that the DC working voltage of the power amplifier is normal, and the output end of the power amplifier is not open, which may be the damage of the power amplifier or the damage of the previous amplifier circuit. Maintenance method: in the case of power, the loudspeaker volume potentiometer open, with a metal touch volume potentiometer sliding end. If there is no interference sound in the speaker, it means that the fault is in the power amplifier; if there is interference sound, it means that the fault is in the pre-amplifier circuit. When the fault is in the power amplifier, measure whether the DC voltage at the output end of the power amplifier is normal. If it is not normal, it may be a fault of the power amplifier integrated circuit and replace it. When the fault is in the pre-amplifier circuit, it can be checked by signal injection.

4. howling fault analysis:
The howling belongs to high frequency self-excitation, mainly caused by the open circuit or failure of the high frequency filter capacitor and the high frequency filter capacitor of the amplifier circuit. Maintenance method: For high-frequency self-excited faults, the parallel capacitor method is mainly used to check whether the high-frequency damping capacitors in the circuit and the small capacitors at both ends of the filter capacitor are open or the capacity is reduced. For low-frequency "beep, beep" sound, the main check whether the decoupling capacitor is open circuit, and check the internal resistance of the power supply, you can try to connect a large filter capacitor in parallel with the filter capacitor of the whole machine.

The power matching between the power amplifier and the sound should consider that the rated power of the power amplifier is slightly larger than the rated power of the speaker. Generally, the recommend ratio is that the power of the power amplifier is 20% to 30% higher than the power of the speaker. This matching method can ensure the stability and sound quality of the system.
The following are detailed explanations and recommendations:
Basic principle: The rated power of the power amplifier should be at least equal to the rated power of the speaker, and ideally should be slightly higher to avoid the situation of "small horse-drawn cart", that is, the power amplifier is not enough to drive the speaker, resulting in poor bass performance and sound quality.
Specific ratio: According to different usage scenarios, the power matching ratio of the power amplifier and the speaker can be adjusted between 1.2 and 2 times. For example, in a home theater system, the ratio of recommend is 1.2 to 1.5 times. This ratio can ensure that the speaker gets enough driving force, while avoiding damage to the speaker due to excessive power amplifier output.
Other considerations: In addition to power matching, impedance matching and frequency response consistency should also be considered. The impedance of the amplifier should match the impedance of the speaker to reduce the risk of sound quality distortion and equipment damage. At the same time, ensure that the frequency response range of the power amplifier covers the frequency response range of the speaker to ensure the integrity and clarity of the music.

1. mono wiring
Mono system usually consists of a speaker and a power amplifier, wiring method is relatively simple. First, connect the positive and negative wires of the sound box with the positive and negative ports of the power amplifier respectively. When connecting, you need to pay attention to the correspondence between the positive and negative poles to avoid the loss of sound quality or damage to the equipment due to the reverse line.

2. stereo wiring
Stereo wiring requires two speakers and a power amplifier, with the left and right channels connected to one speaker respectively. First, connect the positive and negative lines of the speaker to the left and right channel ports of the power amplifier respectively. When connecting, you need to pay attention to the correspondence between the left and right channels to prevent asymmetry or misalignment of the sound. After the connection is completed, the volume and balance can be adjusted to achieve the best listening effect.

3. 5.1 channel wiring
5.1 channel is a kind of multi-channel surround sound, need 5 speakers and a power amplifier support. Among them, the front left and right speakers are responsible for playing the main sound of music, the rear left and right speakers are responsible for playing the surround sound effect, the center speaker is responsible for supplementing the main music, and the subwoofer is responsible for the bass effect.

The wiring method is as follows: connect the center, front left and right, rear left and right, and subwoofer of the power amplifier to the corresponding speaker ports. Similarly, it is necessary to pay attention to the correspondence between the positive and negative lines, so as not to connect the reverse line to affect the sound effect.

After the 5.1 channel system wiring is completed, the sound effect mode needs to be set to 5.1 channel in the playback device to achieve the best playback effect. At the same time, pay attention to the use environment and volume control of the equipment during use to avoid affecting the service life and listening effect.

1. balance connection
Balanced connection means that the signal pin and the ground pin use two different wires to eliminate noise interference and improve the quality and stability of audio transmission. In the balanced connection, the interface can be divided into 1/4 inch and XLR. The 1/4-inch connection is usually used for musical instrument audio equipment, while the XLR connection is usually used in professional audio equipment. When connecting, you need to use a balance line connection between the amplifier and the speaker.

2. unbalanced connection
Unbalanced connection means that the signal pin and the ground pin use the same wire, and the 6.35mm interface and RCA interface are commonly used. In the unbalanced connection, the same unbalanced line connection is also used between the amplifier and the speaker.

3. dual core connection
Two-core connection means that the signal and ground pins use two different wires, one of which is used as the signal output wire and the other is used as the ground wire. This connection requires two dual-core connections between the power amplifier and the speaker.

4. one-way connection
One-way connection refers to the connection mode of transmitting audio signals from the power amplifier to the speaker, which is characterized by the high level of the power amplifier than the speaker. In one-way connection, a single core wire connection is required.

5. bidirectional connection
Two-way connection refers to the connection mode of transmitting audio signals between the power amplifier and the speaker, which is characterized by the equal level of the power amplifier and the speaker. In a two-way connection, a two-core wire connection is required.

It should be noted that when connecting the speaker cable, you need to ensure the correctness of the connection between the positive and negative poles, otherwise it will cause audio distortion or damage the equipment. In addition, the stability and quality of signal transmission should also be considered in the length and quality of the connecting line.

The method of using the audio and power amplifier cable should be noted: use a special] speaker cable connection. The L channel (left channel) of the power amplifier is connected to the left audio_, and the R channel (right channel) is connected to the right audio, taking the left and right as the standard. The "" and "-" of the connecting lines of the two stereos must be connected correctly, otherwise the bass will be canceled out.
1. First of all, look at the back of the amplifier and stereo, whether the audio cable is complete; If not, you have to go to the hardware store to buy-section first, it doesn't have to be too long, otherwise it will be put on the back.
2. It is easy to connect the audio cable. You can also find a vise or scissors. Strip the audio cable from the rubber layer on the outer surface to expose the copper wire inside. Generally, it is in two colors: brass and silver.
3. Remove the skin, twist the copper wire a few times with your hand to make the copper wire harder, and then see that there are red and black terminals behind the power amplifier, and the brass-colored one is connected to the red column. The silver is connected to the black column.
4. The other end of the audio cable is also connected to the back of the audio. Some audio is of the binding post type, while others are more convenient. They are of the snap type. The finger presses the snap, pokes the cable in, and then lets go. The cable is clamped by the snap, which is very firm.
5. For two stereos, connect the lines to both sides of L eft and Right respectively, that is, connect the lines to the left and right respectively.
6. After the power amplifier and audio are connected, it is necessary to input the sound source to the power amplifier. The sound source-DVD player can be used in general situations. If allowed, notebook can also be used, which is more flexible. The connection line needs to use two audio lines with lotus heads at both ends. The L and R channels inserted under OUTPUT at the back of DVD output sound signals, and the power amplifier is also inserted under L and R, but note that it is under INPUT input. In this way, the sound will be output from the DVD to the amplifier, and then from the amplifier to the audio.
7. Now you can turn on the DVD and amplifier, and you should be able to hear the sound. The following is the button description on the front panel of the power amplifier. You can find a small flat-blade screwdriver, plug in the microphone, and slowly adjust the knob while talking until the sound is suitable for your own voice, and you can listen comfortably.