Huawei kpl-w00 notebook does not charge for

Machine model: Huawei kpl-w00

Board No.: daoh96mbafo Rev: F

Fault phenomenon: press boot does not respond, laptop does not charge.

Maintenance process: Huawei’s kpl-w00 notebook does not respond when it is turned on and does not charge.

Huawei kpl-w00 notebook does not charge for Figure 1.

It was found that there was only 6.1v at the common point, which was obviously wrong. The VCC battery was above 7V.

Huawei kpl-w00 notebook does not charge for Repair

Huawei kpl-w00 notebook does not charge for Figure 2.

Test type-C to 19v normal, indicating that the type-C circuit is normal.

Huawei kpl-w00 notebook does not charge for Figure 3.

Observe the motherboard, a standby 3.3V open voltage divider corrode Open circuit, change can be normal display.

Huawei kpl-w00 notebook does not charge for Repair4.

Huawei kpl-w00 notebook does not charge for Figure 5.

This machine uses the charging chip bq25703a, the circuit is a little complicated, share the key points.Take the changed resistor apart again, and let the common point VCC be 6.1v before. Do the experiment with an oscilloscope. The channels are as follows:schematic, q1g level 1 channel, q22 channel, Q43 channel, batt 4 channel. The duty cycle is very small. The waveform can be measured in Q1 Q2 Q3 Q4.VCC can not be measured by multimeter on the right side of Inductor,What an oscilloscope can measure is a square wave.

Huawei kpl-w00 notebook does not charge for Figure 6.

Huawei kpl-w00 notebook does not charge for Figure 7.

Install the standby 3.3V resistor back and measure the waveform.

Huawei kpl-w00 notebook does not charge for figure 8.

Huawei kpl-w00 notebook does not charge for Figure 9.

It is detected that the VCC displayed on Channel 4 is 7.4v, and the same is detected by multimeter. At this time, it is in standby mode, and then look at the startup waveform.

Huawei kpl-w00 notebook does not charge for Figure 10.

When the machine is turned on, Q1 and Q2 are in normal square wave, Q4 directly enters the saturated channel state, Q3 is closed, and VCC 8.4v is output.,Under normal standby mode, the oscillograph is connected with 1 channel Q1, 2 channel Q4, 3 channel bq25703 12Pin SDA, and 4 channel is connected to common point according to channel sequence.