收到同行送来的故障机壹台LG 42LB7RF液晶电视,故障表现为灰屏,该机逻辑板的型号为6870C-0180C。上电,测得逻辑板供电(12V)为11.85V,VGL电压为-4.96V,VGH电压为0V,VGH电压明显异常;VCC电压为1.268V,如图1所示,低于正常值3.3V;VCC1.8V电压为0.68V,也明显偏低。因VCC1.8V来自vCC,于是检查VCC外围电路,如图2所示,发现R136(4702 )在路阻值为5.39k,明显异常。更换R136后试机,故障机修到这里,终于修好值得探讨。,此时测得VCC电压为3.301V ,VGH电压为24.49V。 |
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