例1开机后有“沙沙”声,收不到任何电台,但照明手灯能正常发光。分析与检修:打开后盖,测得整机静态电流约为8mA 正常;用镊子碰触音量电位器的中心抽头,发现喇叭中有“喀喀”声,说明低放电路工作正常。该机变频、中频、检波、低放电路是由单片 TC(D3839A)及其外围元件构成的。用“干扰法”继续由后级向前级检查,当用镊子碰触 D3839A④脚(检波输入端)时,发现喇叭中也有“喀喀”声,表明检波电路工作正 Example 1 after boot Analysis and Overhaul: Open the back cover and measure the quiescent current of the whole machine about 8mA normal; touch the center tap of the volume potentiometer with tweezers and find that the speaker has “Titicaca” sound, indicating that the low-discharge circuit is working normally. Machine frequency, IF, detection, low-discharge circuit is composed of a single chip TC (D3839A) and its peripheral components. With “interference method ” to continue to check from the previous stage to the previous level, when using tweezers touch D3839A feet (detection input), the speaker also found “Titicaca ” sound, indicating that the detection circuit is working