How to Repair Common Faults of Amplifier

Abstract: Power amplifier can make each group of speakers get the best frequency response in the listening space, and it is a very important electrical equipment. After a long period of use, various failures will inevitably occur, so it is necessary for us to master its maintenance methods. When in use, it should be placed in a dry and ventilated place. When the whole machine is not working, there is no sound output, and the sound is light and loud, so it should be handled in time. Let's take a look at Bian Xiao. How to Repair Common Faults of Amplifier

First of all, the whole machine doesn't work

1, failure phenomenon

The fault of the whole machine is that the power amplifier is not displayed after power-on, all function keys are invalid, and there is no sound, just like there is no power.

2. Maintenance methods

When overhauling, you should first check the power supply circuit, turn on the power supply, and measure the DC resistance value at both ends of the power plug with a multimeter. Under normal circumstances, the resistance value is several hundred ohms. If the gap is too large, the power transformer is seriously heated, indicating that there is a local short circuit in the primary circuit of the power transformer. If it is infinite, check whether the primary winding of the transformer is open, whether the fuse is blown, and whether the plug and power cord are broken.

Second, there is no sound output.

1, failure phenomenon

Silent failure means that when operating each function key, there is corresponding status display, but no signal output.

2. Maintenance methods

When repairing the amplifier with protection circuit, it depends on whether the protection relay can be pulled in after starting. If the relay is not activated, measure whether the midpoint power amplifier and overcurrent detection voltage in the power amplifier circuit are normal and whether the output voltage is offset. If the midpoint output voltage is deviated or the overcurrent detection voltage is abnormal, it means that the power amplifier circuit is faulty, and check whether the positive and negative power supplies are normal. If the positive and negative voltages are asymmetrical, the load circuits of the positive and negative power supplies can be disconnected, so as to judge whether the power amplifier circuit is faulty or the power supply circuit itself is abnormal. If the positive and negative power supplies are normal, check whether the power amplifier tube in the power amplifier circuit is damaged.

Third, the voice is light.

1, failure phenomenon

Light tone means that the gain or output power of the amplifier decreases due to the great change of the amplifier stage or the attenuation of a certain link during the amplification and transmission of audio signals.

2. Maintenance methods

When overhauling, first check whether the signal source and speakers are normal, and you can use alternative methods to check. Then check all kinds of switches and control potentiometers to see if you can increase the volume. If everything is all right, it depends on whether the fault is in the previous or the next circuit. For a channel with light tone, the signal output from its front-stage circuit can be exchanged and input to the back-stage circuit of another channel. If the volume of the speaker remains unchanged, the fault lies in the back-stage circuit.

Fourth, it is noisy.

1, failure phenomenon

The noise of the amplifier includes AC sound, sonic boom, induced noise and white noise.

2. Maintenance methods

When overhauling, first of all, it is necessary to judge whether the noise comes from the front stage or the back stage circuit. The signal connection plugs of the front and rear stages can be removed. If the noise is obviously reduced, the fault lies in the front circuit. On the contrary, the fault lies in the following circuit.

How to maintain the amplifier

1. Users should put the amplifier in a dry and ventilated place to avoid working in humid, high-temperature and corrosive oil fume chemicals.

2. The power amplifier should be placed in a safe, stable table or cabinet, so as not to damage or fall to the ground, damage the machine or cause greater man-made disasters, such as fire and electric shock.

3. The power amplifier should be far away from the environment with serious electromagnetic interference, such as the aging of fluorescent lamp ballast, which will lead to the disorder of the CPU program of the machine and the failure of the machine to work normally.

4. After the amplifier is used, the function key should be reset. If the function key is not reset for a long time, its pull button spring will be in a stressed state for a long time, which is easy to cause dysfunction.

5. Before switching the audio power supply, adjust the volume potentiometer of the power amplifier to the minimum, which is one of the most effective protection means for the power amplifier and speakers. At this time, the power amplification of the power amplifier is almost zero, at least in the case of misoperation, it will not cause harm to the speaker.

6, in the case of long-term non-use, especially in humid and hot seasons, it is best to power on for half an hour every day. In this way, the heat generated by the components in the machine can be used to drive away moisture, internal coils, speaker voice coils, transformers and so on. It can be prevented from being damaged by moisture.

7. Every once in a while, wipe the machine surface with a clean and moist soft cotton cloth. When not in use, cover the machine with a dust cover or cloth to prevent dust from entering.

8. The normal working temperature of audio equipment should be 18℃ ~ 45℃. If the temperature is too low, it will reduce the sensitivity of some machines. If it is too high, it is easy to burn out components or cause premature aging of components. In summer, we should pay special attention to cooling and keep the air circulating.