Haier mechanic T90-T notebook does not start for repair

Haier’s T90-T notebook doesn’t start up, and it is preliminarily judged that there is power supply and it can’t work normally. The actual measurement shows that SLP_S3# has no voltage. Finally, a brand-new original South Bridge chip was replaced, and ME was configured. The test of the machine entering the system was all normal.

[Machine model] Haier mechanic T90-T

[motherboard version number] GJ5CNXX

[Fault phenomenon] The notebook does not boot.

[maintenance process]

I received a fault machine T90-T from Haier mechanic. The customer described that the notebook didn’t turn on, and this machine was repaired by peers but not repaired.

When the power-on current is 0.36A, the power is turned off, and the power is turned on again. It is preliminarily judged that there is power supply that cannot be generated normally.

I searched the forum and found a picture, but I also knew it was a common problem. Carefully observing the motherboard, I found that the previous home only soldered the power supply of Duxian.

Repair of Haier’s T90-T notebook without startup Figure 1

The standby 5V 3.3V 1.8V 1.0V of the motherboard is normal, and the core of the 2.5V 1.2V graphics card is 0.85V and the memory is 0.8V. Have you found it by VCCIO?

Yes, the ON-chasing signal is found that S3# and VCCIO_ON are turned on after U24 phase. The measured SLP_S3# has no voltage.

Repair of Haier’s T90-T notebook without startup Figure 2

When the EC foot is tilted up, there is nothing in the survey, and there is nothing found in the map survey SLP_S4#, but there are differences between the physical object and the PDF data.

Repair of Haier’s T90-T notebook without startup Figure 3

I found that the problem was directed at Nanqiao, and it was normal to check the conditions of Nanqiao. Disassemble the South Bridge chip and find the same fault. Disassemble the South Bridge again, measure all the important points of the South Bridge against the drawings through other point diagrams, and find that there is no problem. Put another piece on it, and it still fails.

It is suspected that it is caused by the leakage of the board layer. Dismantle the bridge, find the nearest point of S3# S4# signal output, disconnect it, and then install the bridge back and start the test again. As a result, the failure is still the same.