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Detailed analysis of common faults and treatment methods of pure rear-stage power amplifier

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Time: 2018-09-14

Browse: 2935

Many amplifier enthusiasts have a certain love for the post amplifier. TEANMA小编今天就来详细解析后级功放常见故障及处理办法。 However, after long-term use of the rear-stage power amplifier, it will expose a variety of problems, TEANMA editor today to analyze in detail the common faults and treatment of the rear-stage power amplifier.

Common fault one: pure back stage power amplifier does not output

Phenomenon: pure back-end power amplifier, turn on the power amplifier, the panel indicator lights up, there is no current sound in the sound.

Cause analysis and treatment:

The power amplifier may not hear the current sound, but it does not mean that it is a problem. Try another audio source, check whether the wiring is correct, whether the switch has connected the audio source you output, and whether the speaker is connected. If it doesn't work, check if the relay in the power amplifier is on. If it is on, also check if it is on. If not, check the reason why there is no pull.

Did you hear the pickup sound of the relay when you turn it on? If so, insert the signal line and touch the top of the signal with your hand to hear if there is noise. Turn on the volume potentiometer.

Common fault two: suddenly no sound in the power amplifier workshop

Phenomenon: the power indicator keeps working, but the power amplifier is suddenly silent

Cause analysis and treatment:

Suddenly no sound from the amplifier should be the horn relay pull-in protection. There are many reasons for horn protection. It is common that the performance of the final power tube (or push tube) deteriorates, causing the zero potential to drift. At this time, the output will have a DC component. Then there is the failure of the power supply part, which makes the output of the dual power supply asymmetric, and will also cause zero point drift. The other is that the horn protection circuit itself is faulty, which causes the relay to be weak and unable to reliably connect the load. Check them one by one to troubleshoot.

Common failure type three: The volume potentiometer of the pure rear stage power amplifier fails

Cause analysis and treatment:

,如果质量不好,内部很容易发生接触的现象,一般经过拆卸清洗(酒精、),就能修复。 Potentiometers are mechanical components . If the quality is not good, the internal contact is easy to occur. Generally, the potentiometer can be repaired after disassembly and cleaning (alcohol, alcohol). However, if you are not an expert, it will be difficult to return to the ideal state after disassembly. It is recommended that you change to the same model. If there is no improvement, then the problem is not the potentiometer. Of course, there must be no errors in the connection.

Common fault 4: Noise of the post amplifier

Phenomenon: The noise of the post amplifier is too loud

Cause analysis and treatment:

“接地”。 First determine whether this noise changes with the adjustment of the volume potentiometer. If so, check the connection, shielding, and "grounding" of the input cable, input jack, and volume potentiometer itself . If not, you can check from the output, whether the midpoint of the output tube is drifting, whether the resistance of the output feedback resistor is deteriorating, whether the input capacitor is leaking, whether the output voltage of the bipolar power supply is consistent, whether the power supply filter capacitor is deteriorated, the noise of the transformer and Grounding and so on.

There is also the fact that the noise is present or not. It is the original, and there is a great possibility according to the latter part. Determining whether this noise is present on one or both channels can also speed up maintenance.

Common fault five: Pure back-stage amplifier has a low sound in one channel

Phenomenon: Pure rear-stage power amplifier, one channel of sound is very small, the other channel is normal

Cause analysis and treatment:

,我碰到过 It should be a question of the preamplifier of the amplifier , I have encountered it . The detection method is separated at the demarcation capacitor connected to the front and rear pole circuits, and then the two rear poles are connected together to distinguish whether the fault is in the preamplifier or the rear pole circuit. If the two-channel sound is the same, it is a problem of preamplification.


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