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1、V998+型手机 故障现象:无法正常开机。 判断检修:当手机用机内电池供电时,电池通过电源切换开关管的Q942的⑤-⑧脚送入,并由直流稳压ICU900的⑩脚通过Q942的④脚控制Q942导通,由942的①、②、③脚送出B+电压。这就是机内电池向手机供电的过程。检测电源切换开关管Q942的⑤-⑧脚,测得有4.8V的电池电压输入。按开机键,测得Q942的④脚有高
1, V998 + mobile phone failure phenomenon: unable to boot normally. Judgment overhaul: When the phone is powered by the battery in the machine, the battery is fed into the ⑤-⑧ pin of the Q942 of the power switch tube, and is controlled by the ⑩ pin of the DC voltage regulator ICU900 through the Q942 pin control of Q942, ①, ②, ③ feet sent B + voltage. This is the process by which the battery in the machine powers the handset. Detection of power switch Q942 ⑤-⑧ feet, measured 4.8V battery voltage input. Press the power button, measured the feet of Q942 high