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例1 故障现象:该机拍摄室内和低照度物体时画面正常,拍摄高亮度物体或在晴天拍摄外景物时图像发白,并伴有拉毛。检修过程:打开机壳,在按下面板上的POWER开关时,光圈环随之动作,但用手遮挡镜头时光圈环并不随之改变,据此可基本确认故障位于自动光圈系统。经采用电压检则法对光圈控制比较器IC_(301)测量后,发现IC_(301)的⑧脚电压为8.9V,⑤脚电压为0.95V,均正常。⑥脚电压为1.2V,而⑦脚电压为3.8V(异常),反复检查其⑦脚外围元件未发现异常,判断IC_(301)有问题用AN1358S更换IC_(301)后,故障排除。剖析AN1358S的内部等效电路,它是一种贴片式双运算放大器芯片,
Example 1 Fault phenomenon: The aircraft shooting indoor and low-light objects when the screen is normal, shooting high-brightness objects or when the photo in the sunny outside when the image is white, and accompanied by hair. Maintenance process: Open the case, press the POWER switch on the panel, the aperture ring with the action, but the hand ring when the lens aperture ring does not change, which can basically confirm the fault is located in the automatic aperture system. After using the voltage detection method for the aperture control comparator IC_ (301) measured and found that IC_ (301) ⑧ foot voltage is 8.9V, ⑤ pin voltage is 0.95V, are normal. ⑥ pin voltage is 1.2V, and ⑦ pin voltage is 3.8V (abnormal), repeated inspection of its ⑦ pin found no abnormal external components, IC_ (301) to determine the problem with AN1358S replace IC_ (301), troubleshooting. AN1358S analysis of the internal equivalent circuit, which is a chip dual op amp chip,