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I have a MacBook Pro (Retina, 15-inch, Late 2013) from Mid-2014 which is vintage classed. It is running MacOS Catalina 10.15.7 (not Big Sur which is the later OS available).

Recently I am experiencing rather frequent random sudden shutdowns (multiple per day or near-daily). The screen suddenly becomes dark but the computer is still on. After 20 seconds or so, it powers off completely. This happens when plugged in with charger (not sure if it happens on battery or not). From some of these shutdown events, it looks to be related to code -128, which is an "unknown cause": (Shutdown Cause -128) or possibly related to memory issues.

$ sudo log show --predicate 'eventMessage contains "Previous shutdown cause"'

Filtering the log data using "composedMessage CONTAINS "Previous shutdown cause""
Skipping info and debug messages, pass --info and/or --debug to include.
Timestamp                       Thread     Type        Activity             PID    TTL  
2022-01-06 11:46:14.824317+0100 0xb5       Default     0x0                  0      0    kernel: (AppleSMC) Previous shutdown cause: -128

I have tried resetting SMC, and NVRAM/PVRAM (holding Opt-CMD-P-R on boot), and run the Apple Diagnostics on startup (holding D on boot). I still have the same issue, and Diagnostics didn't find any issues.

Battery health is at 88% (battery and top case replaced in early 2019).

I just discovered that on my charger, the wiring inside is exposed (the outer material protecting them have somewhat broken at a place). I can't tell if there is sufficient damage or not to the wiring. An extreme close-up (hardly visible to the eye) in the photo shows that there has at least been some minimal tearing to the wire:

enter image description here

Is it possible that this can be causing voltage issues? If so, can I use electric tape to cover it up, or do I need to buy a new charger?

I am somewhat hesitant to buying a new charger, because I suspect that the exposed wiring may not be the problem, and that there is a bigger hardware issue at fault – in which case investing further in this vintage-classed computer may be cost inefficient.

I would also appreciate general advice on how to proceed with this matter altogether.

2 Answers 2

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I have had several chargers where the outer cover fails like that.

given the size of the magsafe connector there won't be an easy fix with shrinkfit tube, done that with smaller ones.

Any tape wrapped around will only be temporary, as it will unwrap, get sticky etc.

I found the best solution was to open the charger and shorten the cable so only good outer cover is there. Fiddly and you need to crack the charger case, possible with a sharp knife through the little valley or seam on the charger - do NOT cut too deep... Make sure you leave the charger unplugged for at least 24h before attempting as the caps inside will let you know otherwise...

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You should take a look at this link. The steps for Catalina are:

(MacOS 10.14, 10.15)

  1. Reboot with Cmd+R pressed.
  2. Open Terminal
  3. sudo csrutil disable
  4. reboot in normal mode
  5. sudo mount -uw /
  6. sudo mv /System/Library/Extensions/AppleThunderboltNHI.kext /System/Library/Extensions/AppleThunderboltNHI.kext.BAK
  7. csrutil enable
  8. Reboot and forget about the problem

I have been facing the same problem with my MacBook Pro Mid 2014 Retina 15-inch. This turns out to be a common problem in these MacBooks and after a lot of troubleshooting the only thing that solved my problem was disabling some thunderbolt drivers as shown in the link.

If you want more info on the hardware problem behind this shutdown you can see this video explaining the faulty FDMF 6808N chips in the logic board that cause the issue.

PS. I don't think the charger causes an issue here but you might want to fix it up with some tape. You will buy a new one eventually, especially if you start to see some heat build-up on the adapter.

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