Lenovo g50-45 notebook water does not start repair

Model: Lenovo G50-45

Malfunction: notebook water damage no booting,N machine repair.

Maintenance process:
water damage Lenovo G50-45 notebook has been repaired many times.

Lenovo g50-45 notebook water does not start repair Figure 1.

0.18A, 10 after switch, auto power off returned to standby after more than 10 seconds, and VCC was out of order.

Lenovo g50-45 notebook water does not start repair Figure 2.

Open Xinzhizao Soft to find the location diagram, and find that Capacitor resistor is installed backwards.

Lenovo g50-45 notebook water does not start repair Figure 3.

Lenovo g50-45 notebook water does not start repair Figure 4.

After the boot is corrected, the fault is still 0.18, more than 10 seconds auto power off, which can only be detected step by step.

The first step is to look at the timing diagram:

Lenovo g50-45 notebook water does not start repaire Figure 5.

Direct point, measure + CPU_Normal, APU + core_CORE_NB was normal, PLT was measured_RST is low, it seems that Nb working conditions are not satisfied (this is amd integrated u, only Capacitor VCC near CPU). After a long startup test, it is found that J9 has no VCC.

Lenovo g50-45 notebook water does not start repair Figure 6.

Lenovo g50-45 notebook water does not start repair Figure 7.

Continue to trace the source, from Q41.

Lenovo g50-45 notebook water does not start repair figure8.

Continue to pursue Q41 control level 0V.

Lenovo g50-45 notebook water does not start repair figure 9.

There are only two possibilities: 1 Short circuit, 2 disconnection.No Short circuit was detected after power failure, and Q37 was controlled. Continue to check Q37.

Lenovo g50-45 notebook water does not start repair figure10.

After switch, the G pole of Q37 becomes low level, but the collector is not raised, and the line is broken.

Lenovo g50-45 notebook water does not start repair figure11.

Find the nearest + VSB Jump wire, the cable flies well, J9 also has power, turn on 0.4A again, no current of change, come to the forum to download BIOS, continuously brush 3, the fault is still.During the BIOS brushing time, the BIOS pin was tested without BIOS, and there was a piece selection. Finally, a BIOS was found in the forum. This time Normally booting up is finished. Troubleshooting and maintenance are finished.

Lenovo g50-45 notebook water does not start repair figure12.