Public Broadcasting Power Amplifier Failure Analysis And Repair Method
Amplifier machine’s basic approach
Radio: check the power cord to the protective tube pass, if the power cord off, or fuse poor contact, or check the fuse has blown Amplifier Rectifier bridge rectifier is bad or electrolytic and other components, such as the rectifier diodes or Heap bad put a good bridge components and then check the other lines, such as power amplifier tubes.
Normal signal level indicator light flashes, but no sound output: speaker unit first check whether it is normal, as normal, check the speaker wire that is normal, that is, check the terminal good contact, the normal, which means that the case whether visual or hearing, whether to hear or see the output relay pull, pull, if normal, (if the multimeter) before the measurement of the relay input and output are through, such as unreasonable or relay contacts within the oxidation or ignition achievements made charcoal, or for normal relays.
Power indicator light is no sound output normal, but heard the sound output and relay: first with a multimeter, measure the power Amplifiers The power supply is normal, as normal, that is, the signal input terminal signal line office and hand with the thread through as much of the current sound that is heard the initial discriminant power amplifier part of the normal, that is, whether the light could not shake the signal lead or contact bad, so bad contact, that is measured with a multimeter, is the cord to a failure to handle the normal.
Such as power amplifier output no sound output: the speaker unit is a normal inspection, such as whether the poor contact caused terminal burned, if burning the black terminal, that is clear and to ensure access to normal, screw fastening screws.
Power Protection light is on: the first speaker with a multimeter, measure groups have a short circuit resistance is reduced (normal to not less than 30 ), such as machine outside the line resistance of the normal, that is identified as Amplifier faulty, that is, to boot check .
Sound varying phenomenon is likely possibilities:
1, signal line connection is bad;
2, potentiometer connection is bad; 3, signal coupling capacitors; 4, feedback and other poor contact resistance.
Measurement amplifier board in normal circumstances no more than voice are:
Signal line is busy or coupling capacitors open circuit;
2, front no power supply, power supply part of the measurement;
3, volume potentiometer bad; 4, operational amplifier IC bad will occur until failure.
As pure amplifier sound distortion, failure of parts:
1, the power of a Soft breakdown;
2, positive and negative voltage of a voltage-free or low;
3, change the value of such resistance.
Normal voice level indicator does not work:
1, the first measurement of voltage is normal;
2, and then measuring the signal is sent;
3, measuring components for damage. Treble bass adjustment can not: 1, potentiometers are normal; 2, voltage is normal; 3, resistive and capacitive elements are normal;
4, line is connected or poor contact;
5, solder joints have Weld, and leave welding and so on.
I am an expert from China Toys Suppliers, usually analyzes all kind of industries situation, such as exhaust flame throwers , cigarette socket adapter.
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