IPhone XS Max does not start the fault repair, and the small capacitor leads to no baseband maintenance

IPhone XS Max does not start the fault repair, and the small capacitor leads to no baseband maintenance.

IPhone XS Max was not turned on, and it was found that there was no baseband after replanting CPU. After adding a new capacitor, the fault was fixed.

“Machine model” iPhone XS Max

[Fault phenomenon] The customer described that the machine suddenly turned off during use without warning, and then tried to turn it on, but it could not be turned on.mobile phoneThere are many reasons for the failure of not turning on the machine. When it is suddenly turned off during use, it is mostly that the motherboard has failed, and the specific situation needs to be disassembled to know.

IPhone XS Max is not turned on for maintenance. Figure 1

[Maintenance process] Disassemble the machine, take out the motherboard, connect the adjustable power supply, and judge the approximate fault position by the current first. When the single board is powered on, the current normally jumps to 230ma, then stops at 115ma and suddenly returns to zero after more than ten seconds, and so on. According to the fault current combined with maintenance, it is judged by experience that it is a CPU problem. The main board is layered by using a heating table, the CPU is removed, the solder pad is processed, the tin is replanted, the CPU is installed, and the small components around the CPU are processed. The test frame made by Xinzhi is used to test that the startup current is normal and the display screen is normal. However, the test found that there was no baseband and the card was not recognized, resulting in no signal.

IPhone XS Max is not turned on for maintenance. Figure 2

Re-test some circuits of the baseband, and find that the power supply is short-circuited. Use an infrared diagnostic instrument to confirm that it is a capacitor short-circuited. After the short circuit is removed, add a new capacitor.

IPhone XS Max is not turned on for maintenance. Figure 3

[Maintenance Result] Short-circuit Troubleshooting Use Xinzhi test stand to test that the baseband is back to normal, attach the upper and lower motherboards, put them into the mobile phone for testing, start-up testing, touch normal, baseband normal, network normal, fault repair, and maintenance is over.

This case was originally provided by Xunwei Quick Repair Flagship Store, and it is forbidden to reprint without authorization!