The successful repair of the MacBook A1707’s voltage boost issue highlights how the right tools make all the difference— from the multimeter that pinpointed voltage anomalies to the hot air gun ensuring precise chip handling. For anyone tackling similar repairs, China Phonefix offers a one-stop shop for these essential tools, ensuring you have the precision and reliability needed to resolve even the trickiest hardware problems with confidence.
1. Problem Description
A customer brought in an Apple MacBook A1707 with the issue of power-on without display and no CPU power.
2. Initial Inspection and Diagnosis
Upon measuring with a digital multimeter, it was found that there was no CPU power output.
The CPU power circuit was checked, and the resistance to ground was normal, but the expected voltage was not present.
3. Inspection CPU Power Management Chip
The Digital Oscilloscopes measurement results show that the 41 and 42 pins of the CPU power management chip had normal voltage, but the CPU still wouldn’t power on.
The 48-pin (CPU_VR_EN_R) voltage was measured at 3.3V, which was correct, indicating it was in an "on" state.
Measuring the 43-pin (CPUCORE_VIDSOUT_R) and 45-pin (CPUCORE_VIDSCLK_R) voltages, only 0.778V was observed, which was significantly lower than the expected value.
4. Measuring the PP1V0_S3 Pull-up Voltage
Continuing the measurements, the PP1V0_S3 voltage was found to be only 0.777V, much lower than expected.
Tracing the voltage source, it was discovered that the PP1V0_S0SW was shorted to ground, which caused the low PP1V0_S3 voltage and prevented the CPU from being powered.
5. Component Diagnosis and Location of the Fault
Using a reference board, it was found that the short circuit resistance to ground was 60 ohms.
Even after removing U8285 (the voltage regulator) and capacitors C11L1 and C11L2, the short circuit to ground still existed.
The fault was identified as a shorted CPU, and the CPU model was determined to be SR32Q.
A hot air gun heats solder joints to remove the BGA CPU, a fine-tip Soldering Iron Tip cleans residual solder from the pads, and a BGA reballing kit applies fresh solder balls for installing a new CPU.
After removal, the resistance to ground of the CPU pins was measured and found to be 353 ohms, which confirmed the short circuit fault.
A new SR32Q CPU was installed, and its resistance to ground was measured to be 163 ohms.
Use Thermal Imaging Camera inspect the board for overheating components after the CPU replacement. After powering on, the CPU power voltage was restored to normal.
After powering on, the CPU voltage was detected. Measuring PP1V0_S3 again returned the voltage to normal.
The current gradually changed from 1.3A, 1.4A, 1.2A, 1.1A, to 0.8A, finally stabilizing at 771.3mA, indicating that the power delivery system was functioning correctly.
8. System Functionality Test
After installing the machine, I tested the system and found it to be normal. There was no password lock after logging in.
I performed a functional test using my own test hard drive, and all hardware and system functions were normal.
The repair was successful, and the customer's issue was resolved.
ConclusionMacBook A1707 not display and not CPU power is a problem that many technicians often encounter. The problem usually stems from a fault in the power management circuitry. Phonefix will guide you step by step through the troubleshooting process and introduce the tools needed to fix the problem. By following these steps, a technician can accurately diagnose and repair the problem, restoring full functionality to the device.
