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LG 43LF5100-CA(EAX66725502)有声音黑屏(背光不亮)维修

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Post time: 2022-9-6 11:53:49
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LG43LF5100-CA有声音黑屏(背光不亮),检查主板上背光升压电路的两只33UF/100V电容顶部已鼓包,换后背光还是不亮(主板串接21只3V的灯珠也不亮)。取掉屏背光插头用测试仪点灯条正常,测(取掉屏背光插头)升压电容的正极只有60(用指针表测量的)多伏(这个屏的背光是21只灯珠串联的,单只灯珠的供电是3V)的电压,这个电压不正常,说明背光升压电路还有问题。仔细观察背光取样电路的两只电阻R653(120K)、R656(270K)发现R656的外观不正常,R656已经变值。为了不返修将两只电阻都换掉,换后不插屏背光插头(空载)测升压电容正极上电压升到80(用指针表测量的)多伏,插上屏背光插头电视机工作正常。附上相关的图片。另外再说一下这个电视背光不亮时用强光手电筒照屏幕是没有图像的,以前也修到过55的LG背光不亮时有这种现象,可能是这样设计的吧。

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Post time: 2022-9-21 08:39:57
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