Redmi K30 can’t be turned on

Redmi K30 can’t be turned on

Machine model:Redmi K30 5g

Fault phenomenon:Redmi K30 5g can not be started

Fault analysis: a Redmi k305g was sent to repair by the same company. After power on test,Connect the power supply short-circuit current 56ma was found.Connect the power supply,short-circuit current, mobile phone no booting, need to solve the problem of short-circuit current first.In most cases, after solving the problem of short-circuit current, the mobile phone can be turned on.If the mobile phone is still Won’t Turn On, check the current analysis fault.

Redmi K30 can’t be turned on Figure 1.

The maintenance process of Repeat welding power supply was observed.

Redmi K30 can’t be turned on Figure 2.

In addition, there is a Capacitor on the lamp control output Related circuit.

Redmi K30 can’t be turned on Figure 3.

Press the power on key, touch the motherboard, and find the power supply high temperature.

Redmi K30 can’t be turned on Figure 4.

After removal,Connect the power supply short-circuit current 6mA, which is generally caused by a chip damage on the second terminal Related circuit.

Redmi K30 can’t be turned on Figure 5.

The NFC of Xiaomi mobile phone is easy to be damaged. This is an common failing.

Redmi K30 can’t be turned on Figure 6.

So the NFC was removed and the mobile phone was no longer short-circuit current.

Redmi K30 can’t be turned on Figure 7.

The start-up current is normal, but the battery does not respond to start-up and does not charge. In this case, it is considered that there is a problem with the battery detection pin, but diode value and VCC are normal.

At this time, the peer sent a message asking me if the Xiaomi 10 was repaired. I said it was OK. He said that the Redmi K30 was damaged by charging.

At this time, we suspect that there is something wrong with the charging IC, and it also detects pin through the battery.

Redmi K30 can’t be turned on Figure 8.

Replace a charging IC. Battery boot failure is still the same, with the power supply high temperature, the power supply has been replaced, it is ruled out, that is, there is a problem with the lamp control after the circuit.

Redmi K30 can’t be turned on Figure 9.

The lamp control Capacitor was cut out before. Now Diode value is normal, it is found that Inductor is the first high temperature, so it is replaced with a Inductor.Boot prompt system damage, this situation can only Update System.This is the end of the repair.