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长虹C2591(TDA8362单片机)彩电,图像上长下短,其他全部正常。调RP310场幅变化正常,调RP318场中心有1 cm的移动。测N301(TDA3654)⑧脚电压为12 V(正常为4.8 V),其他几脚电压正常。查外围元件正常的情况下代换场块还是无效,据以往经验:电容失效万用表测不准,故采用逐个并联法(断电焊好后再通电)。当用1 μF/160 V电容并在C308上通电试机时一切正常,此时测N301⑧脚电压也由12 V变为5 V。疑问:使我不解的是为何C308失效会使N301⑧脚电压增高一倍以上,⑧脚接升压电容C313还输出字
Changhong C2591 (TDA8362 SCM) color TV, the image up and down short, all the other normal. Adjust RP310 field amplitude changes normal, transfer RP318 field center has 1 cm of movement. Test N301 (TDA3654) ⑧ foot voltage of 12 V (normal 4.8 V), the other a few feet voltage is normal. Check the external components under the normal replacement field block or invalid, according to past experience: Capacitance failure multimeter measured uncertainty, it uses one by one parallel method (off after welding power). When using 1 μF / 160 V capacitor and power on the C308 test machine when all normal, then measured N301 ⑧ foot voltage from 12 V to 5 V. Question: What puzzled me was why C308 failure caused the N301 ⑧ pin voltage to more than double. ⑧ pin connected boost capacitor C313 also output word