Redmi XMG1902-BR notebook can’t be repaired without power on

Redmi XMG1902-BR notebook can’t be repaired without power on

The standby chip is hot, and the short circuit of EC causes LDO 3.3 to be pulled low; Judging from the problem on the EC side, I found that there was a needle attached to 5V, which caused the EC to burn when it was powered on. Pins are broken, and then an EC is changed. The boot is normal, and the fault is eliminated.

Machine model: Redmi XMG1902-BR notebook

Malfunction: The notebook can’t be turned on without power.

Maintenance process:

I received a Redmi XMG1902-BR notebook computer. The fault described that after the customer changed the fan, the notebook could not be turned on, and the standby chip was hot for 0.18A The short circuit of EC caused the LDO 3.3 to be pulled low.

Redmi XMG1902-BR notebook can’t be turned on without power. Maintenance Figure 1

A disassembled EC chip was replaced, and it didn’t trigger when it was powered on, 0.05A Once the switch indicator on the keyboard was plugged in, the single plug-in battery couldn’t be charged, and the ACOK from the test charging chip was low. After it was cut off, it was judged to be a problem on the EC side.

Redmi XMG1902-BR notebook can’t be turned on without power. Maintenance Figure 2

Short-circuit the five or six pins of BIOS, and the indicator light goes out. At this time, ACOK is high.

Another EC is still the same, that is, a procedural problem. Looking for RT809H brush, after brushing, plug-in standby is normal, press the switch to power on EC and it’s broken again. It’s still the same to return to the initial fault and change another EC.

When the machine is plugged in, it comes out with LDO3.3 and inductor 3.3 and 5 V. The possibility of these voltage strings is ruled out. When the machine is powered on, it will burn EC, which signal must be in string.

After checking the fan socket, I found that a needle had reached 5V, which caused the EC to burn when it was powered on.

Redmi XMG1902-BR notebook can’t be turned on without power. Maintenance Figure 3

Pins are broken, and then an EC is changed. The boot is normal, and the fault is eliminated.