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例1 无伴音,图像正常。该机伴音集成块用uPC1353。干扰功放输入引脚,无声。用万用表R×1kΩ档干扰脚,喇叭有声,由此初步判断集成电路有问题,进一步测脚电压0.6V和正常6.5V相差甚远,查外围元件无损坏,更换集成块,故障排除。例2 伴音中有交流嗡嗡声产生交流声的原因有:(1)伴音功放电流过大;(2)电源电压波动较大;(3)低放有不良耦合。根据不受音量电位器控制这一点,排除前两项,着重查低放电路的耦合电容,用一电解和耦合电容逐一并联,当并联5C_(11)时,嗡声消失,焊下测量,无容量。5C(11)是去耦电容,因无容量,就造成嗡嗡声。
Example 1 without sound, the image is normal. The machine sound integrated block uPC1353. Interfere with amplifier input pin, silent. With multimeter R × 1kΩ file interference feet, speakers sound, thus initially determine the integrated circuit has a problem, further measuring pin voltage 0.6V and normal 6.5V far, check the external components without damage, replace the manifold, troubleshooting. Example 2 AC buzz hum sound generated by the exchange of reasons are: (1) audio amplifier current is too large; (2) power supply voltage fluctuations; (3) low release with a bad coupling. According to the control of volume potentiometer from this, excluding the first two items, focusing on low-coupling capacitance of the circuit, with an electrolytic and coupling capacitors one by one in parallel, when in parallel 5C_ (11), the disappearance of the noise, welding measurements, capacity. 5C (11) is a decoupling capacitor that buzzes because it has no capacity.