Haier S400 notebook power lamp does not light repair

Machine model: Haier S400

Main board number: US45INE1 MB 8L

Fault: Press the power button, and the power indicator does not light up.

Maintenance process:

A Haier S400 notebook computer, the fault is that the power indicator does not light when the access adapter presses the power button.

Haier S400 notebook power lamp does not light repair Figure 1.

Haier S400 notebook power lamp does not light repair figure 2.

Connected to the regulated power supply, the standby current is 70mA, which is abnormal, and the current does not change when the power-on button is pressed. Measuring the power-on button VCC 5V is normal, and pressing 3.3V is also normal; Measure the main VCC and each branch power supply without abnormality.

TouchECWhen high temperature is slight, it is judged that it should be the direction problem of EC or VCC. Measure VCC VCC EC-11pins VCC to zero. At this time, it is judged that it is the problem of EC, internal VCC, and the standby current after removing EC is 7mA.

Haier S400 notebook power lamp does not light repair Figure 3.

The heating table heats the motherboard to 180°or so, and simultaneously blows and welds with SMD REWORK STATION to replace EC. After cleaning the PCB, power on the standby current of 10mA, power on booting up at one time, troubleshooting and maintenance are finished.