I will just preface all this by saying that I have a fairly technical background but have never attempted SMD electronics diagnostics and repair before, I really like the idea and want to learn.
I have a MacBook Pro late 2016 that died maybe four years ago. Over the course of 30 seconds, it got slower and stuttered, until it froze for a second and died. No click from the trackpad anymore, nothing. I started getting interested in electronics repair and decided to give it a shot, so I opened it, removed the battery (one cell was puffy), took out the motherboard and experimented with it for a week. I am so confused by what is happening as there are multiple failure modes.
The motherboard is a 820-00239.
Failure mode 1
When I plug the computer, the voltage checker reads 5V, then 20V. The CPU gets warm, all the rails are on, all the way to S0, I don't find anything wrong. Because of this I put the motherboard back in the laptop. The fans don't start, the display seems broken (just 5 mm of colored jagged lines appear at the top of the display, I can see the cursor moving up there), the backlight is on, and the trackpad works. I plugged an HDMI adapter to use an external display, but that only worked in recovery mode, not for a regular boot. The touch bar is there and responds to touch, but extremely slowly.
Before failure, PPVCC_S0_CPU is present at about 0.626V, then got missing. ALL_SYS_PWRGD, PP5V_S0, P5VS0_EN all went missing (non-exhaustive list).
Failure mode 2
After two, three minutes or so of being up and running, the laptop will shut off — whether the motherboard is in or out of the laptop. At this stage G3H and S5 are there but nothing else. I tested all the rails in the power aliases containing G3H and S5 (all present).
Failure mode 3
If I unplug and replug the laptop, the voltage checker reads 5 V and stays at 5 V. I identified that PP20V_USBC_XB_VBUS, PP3V3_UPC_XB_LDO, PP1V8_UPC_XB_LDOA and PP1V8_UPC_XB_LDOD are present, but PP1V1_UPC_XB_LDO_BMC is not. At this stage, I can't do anything more than that, I have to wait multiple hours (a night?) until it works again. At that point, if I plug the computer, from 5 V we reach 20 V again. According to logi wiki, a missing LDO_BMC is a sign of a broken cd3215 or corrupted bootrom, but I can't see how these two cases explain what happens here.
Since there is no battery, I'd assume something “remembers” that it was on for it to fail consistently afterward. Failure mode 3 is extremely reliable as well, it will happen every time I unplug and replug, and it takes multiple hours for it to work again, certainly more than two hours. I don't think it's related to heat since it takes so long to get back to a working state, so could it be some capacitor holding a charge for so long? And what could cause all of this mayhem?
I am really confused by all of this, but I hope any of this can make sense to you. Thank you for your help!
I have a MacBook Pro late 2016 that died maybe four years ago. Over the course of 30 seconds, it got slower and stuttered, until it froze for a second and died. No click from the trackpad anymore, nothing. I started getting interested in electronics repair and decided to give it a shot, so I opened it, removed the battery (one cell was puffy), took out the motherboard and experimented with it for a week. I am so confused by what is happening as there are multiple failure modes.
The motherboard is a 820-00239.
Failure mode 1
When I plug the computer, the voltage checker reads 5V, then 20V. The CPU gets warm, all the rails are on, all the way to S0, I don't find anything wrong. Because of this I put the motherboard back in the laptop. The fans don't start, the display seems broken (just 5 mm of colored jagged lines appear at the top of the display, I can see the cursor moving up there), the backlight is on, and the trackpad works. I plugged an HDMI adapter to use an external display, but that only worked in recovery mode, not for a regular boot. The touch bar is there and responds to touch, but extremely slowly.
Before failure, PPVCC_S0_CPU is present at about 0.626V, then got missing. ALL_SYS_PWRGD, PP5V_S0, P5VS0_EN all went missing (non-exhaustive list).
Failure mode 2
After two, three minutes or so of being up and running, the laptop will shut off — whether the motherboard is in or out of the laptop. At this stage G3H and S5 are there but nothing else. I tested all the rails in the power aliases containing G3H and S5 (all present).
Failure mode 3
If I unplug and replug the laptop, the voltage checker reads 5 V and stays at 5 V. I identified that PP20V_USBC_XB_VBUS, PP3V3_UPC_XB_LDO, PP1V8_UPC_XB_LDOA and PP1V8_UPC_XB_LDOD are present, but PP1V1_UPC_XB_LDO_BMC is not. At this stage, I can't do anything more than that, I have to wait multiple hours (a night?) until it works again. At that point, if I plug the computer, from 5 V we reach 20 V again. According to logi wiki, a missing LDO_BMC is a sign of a broken cd3215 or corrupted bootrom, but I can't see how these two cases explain what happens here.
Since there is no battery, I'd assume something “remembers” that it was on for it to fail consistently afterward. Failure mode 3 is extremely reliable as well, it will happen every time I unplug and replug, and it takes multiple hours for it to work again, certainly more than two hours. I don't think it's related to heat since it takes so long to get back to a working state, so could it be some capacitor holding a charge for so long? And what could cause all of this mayhem?
I am really confused by all of this, but I hope any of this can make sense to you. Thank you for your help!
