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一、伴音自激故障现象:开机扬声器发出“啪啪”的低频自激声,图像正常。分析检修:根据故障现象怀疑故障来自伴音电路。该机伴音电路由IC401、Q401、Q402、T401等元件组成。其中IC401及外围元件构成伴音中放电路,Q401、Q402及T401等构成功放级。该机出现低频自激现象,怀疑电源内阻增大的可能性较大。该机伴音中放级与功放级的供电电路不同,前者由行输出级供电,通过电阻R401加至IC401第
First, the sound self-excited Fault phenomenon: boot speaker issued a “pop” low-frequency self-excited sound, the image is normal. Analysis and maintenance: According to the fault phenomenon suspected fault from the sound circuit. The aircraft sound circuit consists of IC401, Q401, Q402, T401 and other components. Which IC401 and external components constitute a sound in the discharge circuit, Q401, Q402 and T401 constitute the amplifier stage. The aircraft appeared low-frequency self-excited phenomenon, suspect the possibility of increased power supply resistance. This machine accompaniment sound level and power amplifier stage power supply circuit is different, the former by the line output stage power supply, through the resistor R401 added to IC401