Apple MacBook Air A2159 notebook can't be started for repair

Apple MacBook Air A2159 notebook can’t be started for repair.

The burning machine found that the memory was hot, but it was short-circuited when the memory was removed. It is estimated that the CPU was burnt out, so it was removed together, and it was not short-circuited.

Machine model: 2020 Apple MacBook Air A2159

Main board version number: 820-01958

Malfunction: The notebook cannot be turned on.

Maintenance process:

I received the 2020 Apple MacBook Air laptop, which could not be turned on. The power-on current was set at 0.22mA

Apple MacBook Air A2159 notebook can’t be turned on for maintenance Figure 1

Disassemble the machine, take out the motherboard, and find that the U8245 1 pin with green oil in the picture is burnt out.

Apple MacBook Air A2159 notebook can’t be turned on for maintenance Figure 2

After the power-on test, the current of the motherboard ran to 0.6mA, and all the voltages came out but were not displayed. Because U8245 supplies power to cpu from 3.3 to 1.8v, the measured resistance of 1.8v is normal. The whole board measured the resistance value, and found that the memory voltage resistance value was 1, the power supply of the memory 1.1v_S3 was short-circuited, and the normal resistance value was about 100. The burning machine found that the memory was hot.

The memory is still short-circuited. It is estimated that the CPU is burnt out, so it is not short-circuited. 20 Air A2159 This model CPU loves to be bad, and it is easy to burn the CPU once water enters.

Apple MacBook Air A2159 notebook can’t be turned on for maintenance Figure 3

After installing the cpu memory, it is tested that the resistance values of the memory power supply and cpu power supply are normal, and it is found that the current rises slowly at 0.50-0.51-0.52 after power-on, which is somewhat similar to the current of the memory, and the particle current of the soldering memory is the same.

I found that the brand of memory is different, so I need to change the setting resistor.