Apple MacBook Pro A1990 notebook can be repaired when it enters the water

Apple MacBook Pro A1990 notebook can be repaired when it enters the water.

By looking at the same circuit from point to point, it is found that the capacitor corrosion is severe near the circuit corroded by water. Remove the CD3205 chip near the corroded circuit, and there is slight corrosion under the pin. Clean up the capacitors and resistors with corrosion around them, and stick the CD3205 chip again. It is normal to boost the voltage by 20V.

Machine model: Apple MacBook Pro A1990

Main board version number: 820-01041-A

Fault phenomenon: the notebook does not boot when it is flooded.

Maintenance process:

I received an Apple MacBook Pro A1990 laptop. The fault is that it can be turned on occasionally, but not most of the time.

Apple MacBook Pro A1990 notebook can be repaired when it enters the water

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 1

Disassemble the machine and test that there is no PP3V3_G3H_RTC_X voltage.

Apple MacBook Pro A1990 notebook can be repaired when it enters the water

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 2

At the same time, the input terminal voltage PPBUS_HS_3V3G3HRTC_X is not available, and the resistance to ground is only 13 ohms, which may cause a short circuit in the PPBUS_G3H path. Dismantle the two fuses F7000 and F7001, and confirm that the load terminal is short-circuited. Looking at the same circuit from the point to point, it is found that the capacitor is corroded badly near the circuit corroded by water.

Apple MacBook Pro A1990 notebook can be repaired when it enters the water

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 3

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 4

After dismantling, the measurement PPBUS_HS_3V3G3HRTC_X is also generated.

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 5

But the main power supply 5V still can’t be boosted to 20V.

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 6

Remove the CD3205 chip near the corroded circuit.

Apple MacBook Pro A1990 notebook enters the water and does not start up for maintenance Figure 7

There is slight corrosion at the bottom of the pin. Clean up the corroded capacitors and resistors around it, and stick the CD3205 chip again. It is normal to boost the voltage by 20V.