该机初看,显然是场输出问题,但是,问题没这么简单。再看故障现象,从低频道到高频道换台,场副越来越窄,L H 频段都如此,查TDA8362(42)脚外接的R392(3.6M)另一端电压10伏,明显偏低(正常33伏)查33伏稳压也10伏,换台,频道越高,电压越低,查供电电阻R067(10K)阻值已变大至几百K,换后正常. 本机场震荡电压取至33,伏电阻R392开路或33伏电压为0都会引起水平亮线.长虹changhong用TDA8362(1)都有此特有故障. |
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