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例6 装有CTV222S遥控板的北京8303彩电,搜索存台时图像正常。但换台时,在各个波段均会出现:由低频道向高频道顺序换台或跳越换台后,图像严重扭曲,需要升频微调后图像才能正常。反之换台,图像基本正常。从故障现象上看,似乎与图像中周L103和AFT中周L171(均为TRF1445)变值引起失谐有关。更换两个中周并校准之,故障依旧。由于搜索存台时图像正常,所以有可能是AFT、RF AGC和IF AGC电路发生了故障。对相关元件逐一检查,并对个别元件作了必
Example 6 Beijing 8303 color TV equipped with CTV222S remote control board, search the memory when the image is normal. However, when changing stations, there will be bands in each band: After changing channels from low channel to high channel or after changing stations, the image is severely distorted, and the image needs to be fine-tuned to be normal. On the contrary for Taiwan, the image is normal. From the point of view of the symptom, it seems that it is related to the detuning caused by the change of the value of L103 in the image and L171 in the AFT (both TRF1445). Replace two weeks and calibration, the fault still. Due to the normal image search, there is a possibility that the AFT, RF AGC and IF AGC circuits have failed. The relevant components one by one inspection, and individual components made