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Old 02-06-2023, 03:14 PM   #1
Stephen
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Default A1990 MacBook Pro boot looping

Did a T2 restore. Boot loops constantly then eventually loads the OS.

Did a T2 Restore and revive and OS reinstall. Same issue. Downgraded OS as well nothing.

No visible water damage seen. No burn chips and MacBook has never been worked on.

Once the OS is fully loaded seems good. For a while.

No kernel panic info shows up so definitely curious what’s going on.

It does boot fully into safe mode without issue.
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Old 02-06-2023, 03:43 PM   #2
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Default Re: A1990 MacBook Pro boot looping

Check each and every SMBUS line.
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Old 02-07-2023, 04:15 AM   #3
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Default Re: A1990 MacBook Pro boot looping

205/2000
Good News and bad news! This kind of problem in my past maintenance experience, encountered a lot of similar models of similar failures, are a problem, CPU bad, BAD CPU! BGA CPU replacement perfect solution! If the appearance of the test, no problem, other measurements, are redundant!
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Old 02-07-2023, 05:28 AM   #4
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Default Re: A1990 MacBook Pro boot looping

Good to know. From where do you source a replacement CPU? Donor board or can you share the details of a good vendor with reballed CPUs?
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Old 02-07-2023, 08:30 PM   #5
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Default Re: A1990 MacBook Pro boot looping

We generally recycle chips from customers who scrap their motherboards, but we also get them from our peers. Buying them online requires a certain element of luck, which involves, sellers and buyers, IC dismantling, manual problems, and temperature control, if you don't handle it well, it will break!
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Old 02-07-2023, 08:44 PM   #6
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Default Re: A1990 MacBook Pro boot looping

Sigh it’s a i9 32GB board. Sucks this is a bad CPU or GPU.
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Old 02-08-2023, 01:54 AM   #7
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Default Re: A1990 MacBook Pro boot looping

There is another solution to this problem, which is to modify the circuitry, to solve the reboot problem, but the researchers have not yet published this solution, and friends around me have learned that it is partially solved by modifying the temperature control, you can go into safe mode, view the system error log, find the corresponding point to modify the circuit! You can try... !
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