Second apple Macbook Air A1932 notebook does not boot

Second apple Macbook Air A1932 notebook does not boot.

Confirm that T2 may have a fault, check that T2 is not short-circuited, and trace that T2 external BIOS waveform is normal. Rom has started to work, and T2 has also turned on the CD3215 I2C bus with 1.8v waveform and voltage. In this case, directly replace the CD3215 chip, and both of them can be changed together, which can boost the voltage, boot normally, and turn on the machine perfectly.

Machine model: apple Macbook Air A1932

Malfunction: The notebook does not boot.

Maintenance process:

I received an Apple MacBook Air A1932 notebook computer, which is the second repair machine, and it is not boosted, so it is not online after recovery.

The bare board’s current is a little high without boosting, and the short circuit of the periphery of the CD215 chip and the U7800 PMU chip is not measured.

Second apple Macbook Air A1932 notebook does not boot figure 1

When the current is set at 279mA, the obvious heating of T2 is observed by infrared detection, and it is confirmed that T2 may have a fault.

Second apple Macbook Air A1932 notebook does not boot figure 2

After plugging in, the CD3215 should send out three LDO voltages of 3.3v 1.8 v1.1v, and then send them to the charging IC9240HI chip through the isolation tube to complete the first step-up of 12V. At this time, the voltage at the common point does not mean that the step-up of the CD3215 is completed.

After the common voltage is turned on, PP3V3_G3H_RTC_R continues to be generated to supply power to cd3215. At this time, PMU7800 starts to work and successively outputs 1.8SLPS 2RPP1.1PP3V3Awake 0.82v0.9V and other voltages to supply power to T2. T2 starts to work, and its internal configuration rom and external ROM work. T2 chip turns on cd3215 through I2C SCL SDA bus, thus completing 20v boost. Continue to trace the subsidiary circuit of T2, and inquire step by step according to the time sequence.

Check that T2 has no short circuit, and trace that T2 external BIOS waveform is normal.

Second apple Macbook Air A1932 notebook does not boot figure 3

Rom has started to work, and T2 has also turned on the CD3215 I2C bus with 1.8v waveform and voltage. In this case, directly replace the CD3215 chip, and both of them can be changed together, which can boost the voltage, boot normally, and turn on the machine perfectly.