Lenovo B575E notebook Won't Turn On repair

Lenovo B575E notebook Won’t Turn On repair

Machine model: Lenovo B575E

Version number: 11314-1 48.4vv01

Lenovo B575E notebook Won’t Turn On repair Figure 1.

Fault phenomenon: power on standby notebook no power on

Maintenance process: three under five divide two machine, full board drawing.

Lenovo B575E notebook Won’t Turn On repair Figure 2.

After measuring 3v5v standby, it was found that the standby VCC was 0.02, but it dropped to 0.004 after a while.

Lenovo B575E notebook Won’t Turn On repair Figure 3.

As soon as I saw this was wrong, I called 3v5v, and Inductor was Short circuit, so I measured the waveform of 3v5v, and directly showed the figure above.3V standby test point.

Lenovo B575E notebook Won’t Turn On repair Figure 4.

3V waveform.

Lenovo B575E notebook Won’t Turn On repair Figure 5.

5 V standby test point.

Lenovo B575E notebook Won’t Turn On repair Figure 6.

5V waveform.

Lenovo B575E notebook Won’t Turn On repair Figure 7.

Obviously, 3V waveform is abnormal, saw tooth is very obvious, replace 3V Capacitor.

Lenovo B575E notebook Won’t Turn On repair figure 8.

It is normal to change the waveform of 3V Capacitor, but the standby mode still changes from 0.02A to 0.004. The original one is 3V standby, and VCC does not flash. Press Switch and then turn on 3v5v standby.This is the end of the repair.It’s the problem with the 3V standby filter Capacitor. Let’s take a picture of booting up.