故障表现为:不开机 维修与分析:通电试机,测3.3v偏低,断开负载,3.3V正常,用 手摸主IC 发烫,跟换U400(MT8227),试机,3.3V正常,但还是不开机,跟换U401并抄写程序,能开机,背光亮,无图,测IC外围供电,发现C127处无1.25V,用导线连1.25V,试机,故障机修到这里,终于修好值得探讨。。 |
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