OnePlus 7 can't boot repair

OnePlus 7 can’t boot repair

Machine model: onePlus 7
Fault symptom: Won’t Turn On

Maintenance process:
Received one plus seven, and no booting is used normally for fault description.

OnePlus 7 can’t boot repair Figure 1.

Fault analysis:

The first end and the second end of Diode value is normal, but the machine of Connect the power supply OverLoad is either a backlight boosting circuit Short circuit or a small coder boosting Capacitor Short circuit. If the diode diode value at the second end of the back test is 200, it is the problem of the backlight back-stage circuit, and if it is 400~800 Short circuit, it is the back-stage of small coder.

Maintenance process:

Open the scanning chart of Xinzhizao Soft, we know that earpiece and speaker of this model have independent small coder power amplifier chips respectively.

OnePlus 7 can’t boot repair Figure 2.

Turn the VCC down so that the motherboard short-circuit current can find the coder shielding cover high temperature on it.

OnePlus 7 can’t boot repair Figure 3.

When shielding cover was disassembled, it was observed that it was Inductor high temperature, which had left a burning mark on shielding cover.

OnePlus 7 can’t boot repair Figure 4.

Remove Inductor on the left side of small coder, and see that welding pin has burned a hole. If auto power off is removed, it won’t feel OverLoad, but earpiece is silent. Replace Inductor with Inductor OverLoad.

OnePlus 7 can’t boot repair Figure 5.

There are three big Capacitor on the left, which are the boost Capacitor of small coder.

OnePlus 7 can’t boot repair Figure 6.

No Short circuit was found in the measurement, and Connect the power supply OverLoad was put back into Inductor. These three Capacitor are not high temperature, and diode value is slightly lower. After removing the left two Capacitor,diode value is restored,Connect the power supply is no longer OverLoad.