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长城JTC 472和长风同属一种机芯。通电后出现三无,有“吱吱”叫声,根据维修经验初步判断是行停振所致。测电源主输出+120V(正常106V略偏高)怀疑是行振荡电路启动供电部分元件变质或损坏。测IC501(33)脚TA7698行场供电输入脚,电压为0V(正常为8.8V)拆下R409电阻器已开路,换上同规格电阻后故障排除。②图像上部略有压缩,并有数条亮线。造成上述故障原因多半是场输出电压不正常所致。测场输中心是25V(正常为25.5V)略偏低。测V306三极管集电极电压42V(正常58.8V)偏低许多。拆R325电阻发现开路更换后故障消除。
Great Wall JTC 472 and Changfeng belong to the same kind of movement. After the emergence of three non-power, a “creak” sounds, according to the initial assessment of maintenance experience is due to stop vibration. Measure the power of the main output + 120V (normal slightly higher than the 106V) Suspected line oscillating circuit to start the power supply components deterioration or damage. Test IC501 (33) feet TA7698 field power input pin, the voltage is 0V (normal 8.8V) Remove the R409 resistor has been open, put on the same specifications after the resistance troubleshooting. ② slightly compressed upper image, and a few bright lines. Caused by the failure of the above reasons are mostly caused by the field output voltage is not normal. The center of the measuring field is slightly lower than 25V (normal 25.5V). Measured V306 transistor collector voltage 42V (normal 58.8V) much lower. Remove the R325 resistance found open replacement fault eliminated.