U301 is a tool that helps resolve the issue of an unresponsive M1 MacBook Air. It enables the reading and writing of data on the USB C ROM chip. Compatible with all MacBooks that have a Type C port from 2016 to 2020, U301 comes with the original ROM data for these devices. Today, we will explain how to utilize U301 for fixing the problem of a non-booting M1 MacBook Air.
Initially, upon attempting to power on the MacBook Air, we encounter the issue where the device fails to turn on.
The MacBook Air is disassembled to conduct additional tests. The back cover is removed and the battery is disconnected. Next, the screws and motherboard are taken out, and the battery flex cable is detached. Finally, the heatsink on the motherboard is removed.
Connect the BY3200 to the DC power supply and provide power to the motherboard. Observe erratic fluctuations in current and voltage, with the voltage oscillating between 0 volts and 5 volts. This indicates an unstable boost in the power supply line of the motherboard, leading to the issue of it not turning on.
After examining the bitmap, we locate L5840 along the primary power supply line. By referring to the drawing, we search for L5840 and discover that it corresponds to the output voltage of PP3V8 AON VDDMAIN. Subsequently, we proceed to measure the voltage of L5840, which is confirmed to be within the normal range.
Next, we assess the operational environment for voltage amplification ranging from 5 volts to 20 volts.
Locate U8100 on the bitmap, and then search for U8100 on the drawing to find the listed output voltages.
The voltage in standby mode usually requires measurement. Consider L8230 as a case in point. Locate L8230 on the bitmap and verify that the voltage is within the normal range.
Continuously measure additional inductors and confirm normal voltages. Proceed with the measurement of LC320 and locate its corresponding position on the drawing. The output voltage for LC320 is PP5V S2, which is within the expected range.
The voltage boost from 5 volts to 20 volts has been determined to have favorable working conditions. Consequently, it is necessary to rewrite the ROM data of CD3217. Locate the ROM chip labeled UF400 on the provided drawing and identify the SPI CLK signal. Proceed to locate the UF260 ROM chip on the bitmap and proceed with its removal. Begin by applying Paste Flux, and then use a Hot Air Gun at 420 °C and airflow 4 to remove the chip.
Attach the chip to U301, ensuring that the pin of the chip is properly aligned. Proceed to connect U301 with a Windows computer.
Start by opening the software, then click on “Read ID”. Choose the appropriate file and click “Open file”. Next, select “USB C Original Data” and locate the matching model.
Clicking on “Auto Program” will result in the successful writing of the data.
Detach the chip. Reinstall the chip back into the motherboard. Connect the motherboard to power. The voltage, which has been boosted from 5 volts to 20 volts, returns to normal. The current jump is also good, indicating that the motherboard is powered on.
After disconnecting, activate the battery to ensure the MacBook can turn on. Once activated, proceed with installing the motherboard for testing. The MacBook now powers on without any issues, indicating that the fault has been resolved.
U301 is available for purchase on REWA Shop. For further information, you can reach out to our sales team. More M1 MacBook repair content will be shared by REWA in the future. If you have any specific topics related to M1 MacBook repair that interest you, please feel free to leave a comment.
