Hello. I have one A2289 (820-01987-A) device. The Apple logo appears and the device resets. I connected it to an external display and disabled the socket of its own display. When I press the ALT key, the disc symbol appears, it does not reset or shut down, but the system does not start up in any way, when I make a selection, the password screen does not appear on the black screen. When I connect the system disc from the external display to the external display, when I make a selection to set up the system, it stays on the black screen after a while. the device turns off. There was a trace on the U3701 as if it had exploded, but it could see wifi on the external screen. I removed U3701, but the result is the same reset. Where might the problem be? What should I do? Can you help me?
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Thank you for the link. I made the measurements and the following PPVCCEDRAMS0_EN_FILT_BUF signal is missing. When the device came to me, the screen was defective. I tried the working screen, but it turns off.
PP0v95_S0_CPUVCCIO_REG_R : 0.97v
PVCCIO_EN : 3.3v
PPVCCEDRAMS0_EN_FILT_BUF : 0vComment
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Measure (carefully) the voltage to ground on each side of R7766.
Next, remove all power -> measure the resistance to ground at R7766. Post the measurements.Comment
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while there is power . I measured both sides.
R7766 .
1 no : 0.5v
2 no : 0v
when all power is off .
1 no : 0
2 no : gnd 0.5
C7777 . PP3V3_S5 = 3.3V ( After a while 3.3v disappears )
Resistance 47k seems correct.Last edited by kartal; 12-08-2023, 02:50 AM.Comment
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Measure the voltage to ground of the following:
PP3V3_S5
PVCCEDRAMS0_EN ; this signal is then fed into the U7712 gates to wave shape / clean up the same signal and results in being PVCCEDRAMS0_EN_FILT_BUF
ALL_SYS_PWRGD_R ; this signal must be a logic HIGH to denote that all power rails are validComment
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these voltages exist.
PP3V3_S5 : 3.3v
ALL_SYS_PWRGD_R : 1.8vComment
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But voltage at R7766 is 0 volts? Continue to review the signal voltage between R7766 and the above. The same logic voltage must appear at R7766 unless the buffer gates are defective in this signal path flow.Comment
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R7766 1 NO: 0.15vComment
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Hi everyone - first time poster on here looking to embark on my first repair! Thank you in advance for any help!
My Macbook only turns on when the charger is plugged in and only the trackpad and fans show signs of life. The display, caps lock light and touchbar do not turn on. There was previous liquid damage to the touchbar but after cleaning and drying the laptop was operational for a year without any issues. There doesn't seem to be any sign of liquid damage to the board, at present.
What I have done so far:
- All of the routine diagnostic methods including... -
Hi everyone. Just a reminder I am not a professional repair technician, fixing Apple electronics is my hobby.
Recently got my hands on MacBook Pro A2289 with interesting behavior. Pristine condition, no water damage, no visual issues whatsoever. It has no image, no CapsLock, no life except the fan is spinning. But it is able to boot into DFU and recognized by another MacBook. I tried to revive and restore the laptop, but the process ends when the MacBook usually should show an Apple logo with a progress bar. I assume the main power lines and T2 are working. It seems like the Intel... -
Hi,
I hope this is the correct place to post about this device. I originally posted regarding this on iFixit so see the details from that post below:
"I'm hoping someone can give their opinion on the symptoms I'm seeing before I spend any more time and put money into this. I got this MacBook from a customer and after looking at it they decided they didn't want it.
It doesn't turn on and there's no visual signs of life. I have tried resetting the NVRAM, SMC, power cycling, unplugging the battery, using the charger with the battery unplugged. Removed the... -
Dear friends,
a close friend of mine gave me this machine, she told me that the last days the fan was going high and that it was heating up too much for the usual things, and that suddenly one morning it didn't start anymore .
I opened it and inspected carefully with a high magnifying lens, found no oxydized spots but a short on PPBUS_G3H , then a blown U6903.
I changed U6903 with a new one, PPBUS_G3H became 558 (measuring with red probe to gnd , and black on F7000) , PP3V3_G3H_RTC 463.
Now when I plug the usbc cable (original Apple 61W power supply), nothing starts automatically,... -
I have a problem I'm hoping someone can help me with. I have an A2289 MacBook that had some liquid damage. After repairing any areas that had corrosion, I was able to get it to show 20v but only .01a on the multimeter. It was consistent on all ports, however I could not get the MacBook to go into DFU mode. I read that I should refllash U4770 and after grabbing the bin from this site I did just that. After soldering the chip back on the board, now I have DFU mode, but the thing is, it won't revive or restore, giving me the error that the device left the DFU state or something to that effect. The...
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