Apple MacBook Air A1466 notebook Camera can't be opened for repair

Apple MacBook Air A1466 notebook Camera can’t be opened for repair

Machine model: apple MacBook Air A1466

Motherboard model: 820-00165-A

Fault: Notebook Camera can’t be opened.

Maintenance process:

I received a MacBook Air A1466 notebook motherboard. Fault description Notebook water damage was turned on, but the front Camera could not be opened, indicating that it was not connected.

Appearance inspection shows that the position of motherboard corrode is near BIOS and CPU MOSFET, and it has been repaired, and Camera special IC U3900 has also been replaced.

Put it into a good chassis for testing, and really don’t recognize Camera. Open the drawing.

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 1.

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 2.

Starting with Camera interface, J4002 consists of five parts:

VCC part PP5V_S3RS0_ALSCAM_F
MIPI data part, there are 2 pairs
I2C_CAM data part 1 pair
The wake-up signal of CAM_SENSOR_WAKE_L_CONN Camera, which is the wake-up signal of forcing GND at low level through R4031 O ohmic resistor.
GND。

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 3.

Measure the above key signals, and find that there is an error of several ohms in MIPI_CLK_CONN_N by measuring the impedance to the ground. If L4009 is removed,short-circuit is directly removed, and the fault remains.

From the power-on measurement, the main V VCC is very stable, without auto power off, measuring I2C_CAM_SCK signal,VCC is only 0.9V, holding the board and testing normally, it should be 1.8V VCC tests of other parts of the interface are generally normal. Next, trace the I2C_CAM_SCK part.

According to the drawings, the 1.8V_CAM is pulled up by 1K resistor, and the test shows that 1.8V is normal, the impedance to ground is normal, and the fault still remains when two 1K resistors are replaced.

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 4.

There are five reasons for the analysis:

U3900 is bad, not as good as welding;
2.U3900 working conditions are abnormal;
There is something wrong with EC U5000;
4.U4000 Camera memory particle problem, defect, working condition, not available;
Bad interface of J4002 Camera.

Replace Camera J4002 interface, replace EC U5000, replace u3900, replace u4000, and check U3900. From the reset inquiry, there is 3.3V, and the IC reset signal comes out. There must be no problem with this IC.

Remove U3900 and make on-off measurement on the bottom pin bit, all of which are normal.

Measure Camera 25M CLK of U3900 with oscilloscope for comparison. Good board has perfect waveform.

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 5.

Apple MacBook Air A1466 notebook Camera can’t be opened for repair Figure 6.

Good board measurement found that Camera 25M CLK had a problem. Look at the drawing, this CLK was output by U1900, and this part was cleaned by corrode near BIOS. Replace all the related IC of CLK near U1900, and the waveform measured by oscilloscope will be output perfectly again.