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[例1]BT5080H型CRT背投彩电,图像会聚不良。分析与检修:按“遥控会聚”键,无会聚方格出现。测VD872、VD870输出端均无±20 V输出。查C819正极无300 V。测XS802B无220 V交流输出,SR801继电器未吸合,N802副电源未工作,推测可能是保护电路动作。测V851的A极电压为0 V,G极电压为0.7 V,A、K极已导通,致使V822、V823截止。SRS0l继电器失电,V851 G极受控于±20 V过流保
[Example 1] BT5080H CRT rear projection color TV, poor image convergence. Analysis and Overhaul: press “remote control convergence ” button, no convergence grid appears. Measured VD872, VD870 output no ± 20 V output. Check C819 positive 300V. Measured XS802B 220V AC output, SR801 relay is not closed, N802 deputy power does not work, speculated that the protection circuit may be action. Measured V851 A pole voltage is 0 V, G pole voltage is 0.7 V, A, K pole has been turned on, resulting in V822, V823 deadline. The SRS101 relay is de-energized and the V851 G is extremely controlled by ± 20 V overcurrent protection