海信SR5468彩电图象拉丝,无信号时光栅左右两侧扫描线稀疏
根据故障现象,首先检查了LA7680(13)静化电路,行输出级,行推动级行AFC电路均未发现故障所在,当测量LA7680(28)在路电压时,忽然关机,经查行输出管损坏,换上行管故障恢复原样,当测LA7680行供电端电压时发现比正常值低0.7V(正常值7.7V)查C421 100UF/16V失效,换上一切正常。
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