Lenovo Xiaoxinchao 7000-13 notebook is not powered on for repair.

After disassembling the test, it was found that the power supply did not pass through the common terminal, and the resistance of the common terminal was measured at 0 ohm. It means that the short circuit caused the protection. After measuring each large inductance and disconnecting each test point, no short circuit was found, so we had to use the burning machine method.

Machine model: Lenovo Xiaoxinchao 7000-13

Main board number: 1701A_05_01 REV:MP

Fault phenomenon: Lenovo Xiaoxinchao 7000-13 notebook is not powered on.

Maintenance process:

As a result, it was found that the capacitor of the power supply pin filter of the CPU power supply chip was short-circuited at fault point C6705. After the replacement, the resistance of the common point became more than 400 ohms. After power-on, the notebook can be turned on normally, but it was found that the battery could not be charged. Both the battery and the adapter can be turned on, and the battery can be found, but it cannot be charged.

The charging and discharging circuit ISL95521 is tested. In the case of external power adapter, it is found that PIN1 ACIN 2.1V is normal (the potential of this pin is 0v without adapter), but the power supply of PIN2 AC0K is 0V (the point of this pin should be about 3.2v in the case of adapter). The external R5914 is tested. One end of this resistor is connected to+V33A _ EC (3.3V), and the other end is connected to ISL9221.

It is found that this resistance has become more than 10 megabytes. After replacement, the charging fault was eliminated and the machine was repaired.