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IPhone 11 has no sound (volume key cable corrosion)

iPhone 11声音三无
IPhone 11, the fault is that the whole board is silent. After receiving the machine, we tested it first, and found that the volume key didn't respond when pressed, the recording function didn't work, and there was no response when the setting was turned on to adjust the volume. We first checked the volume key after disassembling the machine, and found that the volume key had moldy traces. How to operate and maintain it? The following is a detailed introduction!

Shenzhou nh-50hp does not boot (CPU power supply chip is damaged)

神舟nh-50hp不开机(CPU供电芯片损坏) 图2
The nh-50hp of Shenzhou, the customer said that it would not be turned on after installing a sound card. The test found that it would not be powered off without installing a cpu fan, and it was detected that there was something wrong with the temperature control circuit of the cpu circuit. The ntc resistor above was normal, but the resistor below was missing, which made it impossible to divide the voltage in series. The specific maintenance process was as follows:

OPPO R9S Plus black screen plus touch failure (virtual welding of power supply output inductance)

OPPO R9S Plus黑屏加触摸失灵
OPPO R9S Plus, the fault is black screen plus touch failure. Take the motherboard out for testing. Since it is a touch failure of the black screen, let's first check whether the appearance and resistance of the seat display seat are normal. After testing, we found that there is no missing piece near the seat, and the resistance values are also normal. We also measured the display power supply and backlight power supply, which shows that it is not a display problem. At this time, we need to think differently ......See below for details: