The iPhone XS Max does not turn on the device to repair the fault, and the small capacitor causes no baseband repair

The iPhone XS Max does not turn on the device to repair the fault, and the small capacitor causes no base band repair

The iPhone XS Max does not start up. After relocating the CPU, it is found that there is no signal in the base band, and the power supply is short circuit. Use the infrared diagnostic instrument to confirm that the capacitor is short circuit.

【 Model 】iPhone XS Max

[Fault phenomenon] The customer described that the machine suddenly shut down in the process of use, without warning, and then tried to turn it on but could not turn it on. There are many reasons for the failure of the mobile phone is not switched on, the use of the process of sudden shutdown, it is mostly the motherboard fault, the specific situation needs to be dismantled to know.

[Maintenance process]

Remove the machine, take out the motherboard, connect the adjustable power supply, first through the current to judge the approximate fault location. When the board is powered on, the current jumps to 230ma normally, and then freezes at 115ma for more than ten seconds and suddenly returns to zero. This cycle goes on for several times. According to the fault current combined with the maintenance experience, the CPU problem was judged to be the problem. The motherboard was stratified with a heating table, the CPU was removed, the welding pad was processed, the tin was re-implanted, the CPU was installed, and the small components around the CPU were processed. The Xinzhi measuring frame was used to test that the startup current was normal and the display screen was displayed normally. However, the test found that there was no base band, no recognition card resulting in no signal.

The base band circuit was detected again, and the short circuit of power supply was found. The infrared diagnostic instrument was used to confirm that the short circuit was capacitor short circuit. After the short circuit was cut out, the new capacitor was replaced.

[Maintenance result]

Use Xinzhi test rack to test base band recovery, fit the upper and lower motherboards well, install them into the mobile phone for testing, boot test, touch normal, base band normal, network normal, fault repair, the end of maintenance