driftkingisback
New member
Hi everyone,
I’m a beginner doing board-level repair as a private hobby. I’m not a professional technician, but I’m very interested in learning and I would really appreciate some guidance with this MacBook.
The machine is a MacBook Pro A2779, m3
Output 20,3 v
3,21 ampere 63watt
The MacBook was simply sitting connected to the charger when it stopped working. There was no liquid damage or accident that I know of.
The interesting thing is that the MagSafe LED is green and I can measure approximately 20V at the input.
When I press the power button, the power supply drops/restarts. If I hold the power button for more than about 10 seconds, the whole sequence seems to restart and I get the same behaviour again.
I opened the bottom case and inspected the board visually but could not see anything obvious.
I also have a thermal camera, and one component marked 2R7 gets significantly hotter than the surrounding components when I try to power the machine on.
I have now disconnected the battery for testing. With the battery disconnected, two the fans starts spinning. I have not removed or replaced any components.
I also have a multimeter and recently bought an oscilloscope because I would like to learn proper board-level troubleshooting.
What would you recommend as the next diagnostic steps?
I would really like to work through this systematically rather than randomly replacing components.
For example, should I start with:
1. Measuring resistance/diode mode to ground around the 2R7?
2. Identifying exactly which power rail the 2R7 belongs to?
3. Checking PPBUS_AON / PPBUS_G3H?
4. Checking PP3V3_AON / PP3V3_S2?
5. Checking for shorts on the main power rails?
If someone can give me a step-by-step measurement sequence, I’m happy to post all the measurements and photos here as I go.
I have the schematic/boardview available and can locate the components and test points if someone tells me what to measure.
I would especially appreciate advice on where to start and how to follow the fault through the schematic.
One more important thing: the internal SSD contains around three years of family videos of our children which I have not backed up yet. I therefore don’t want to perform any procedure that could unnecessarily put the data at risk.
I’m not looking for someone to simply tell me which chip to replace. I’d actually like to understand the troubleshooting process and hopefully get my first successful board repair.
Thanks in advance for any help!
I’m a beginner doing board-level repair as a private hobby. I’m not a professional technician, but I’m very interested in learning and I would really appreciate some guidance with this MacBook.
The machine is a MacBook Pro A2779, m3
Output 20,3 v
3,21 ampere 63watt
The MacBook was simply sitting connected to the charger when it stopped working. There was no liquid damage or accident that I know of.
The interesting thing is that the MagSafe LED is green and I can measure approximately 20V at the input.
When I press the power button, the power supply drops/restarts. If I hold the power button for more than about 10 seconds, the whole sequence seems to restart and I get the same behaviour again.
I opened the bottom case and inspected the board visually but could not see anything obvious.
I also have a thermal camera, and one component marked 2R7 gets significantly hotter than the surrounding components when I try to power the machine on.
I have now disconnected the battery for testing. With the battery disconnected, two the fans starts spinning. I have not removed or replaced any components.
I also have a multimeter and recently bought an oscilloscope because I would like to learn proper board-level troubleshooting.
What would you recommend as the next diagnostic steps?
I would really like to work through this systematically rather than randomly replacing components.
For example, should I start with:
1. Measuring resistance/diode mode to ground around the 2R7?
2. Identifying exactly which power rail the 2R7 belongs to?
3. Checking PPBUS_AON / PPBUS_G3H?
4. Checking PP3V3_AON / PP3V3_S2?
5. Checking for shorts on the main power rails?
If someone can give me a step-by-step measurement sequence, I’m happy to post all the measurements and photos here as I go.
I have the schematic/boardview available and can locate the components and test points if someone tells me what to measure.
I would especially appreciate advice on where to start and how to follow the fault through the schematic.
One more important thing: the internal SSD contains around three years of family videos of our children which I have not backed up yet. I therefore don’t want to perform any procedure that could unnecessarily put the data at risk.
I’m not looking for someone to simply tell me which chip to replace. I’d actually like to understand the troubleshooting process and hopefully get my first successful board repair.
Thanks in advance for any help!