Inexplicable internal damage to USB-C ports: cause?

Sounds like just the I/O Boards which contain the USB-C ports were replaced.

I can tell you from supporting thousands of our organization's USB-C Apple laptops that over half of them tend to have accidental liquid damage on the contacts inside the USB-C port. Once the I/O Board is removed, it is usually easy to see the corrosion caused by the liquid. Because the ports are so tiny, the contacts are closer together than with most older ports (Thunderbolt 2/mini-display ports also tend to have this issue to a lesser extent) so if even just a single drop of liquid enters the port, it is likely to start corroding the contacts as it will easily make contact with two pins. With electricity flowing through the drop of liquid from touching two pins, a chemical reaction begins and before long corrosion will form on & between those two pins.

Keep in mind that it may just be a small liquid spill on the table nearby the laptop where none of the actual puddled liquid ever touches the laptop, but it can still cause drops to splatter much further. Just because you never spilled anything near the laptop doesn't mean someone else didn't have an accident & cleaned it up without saying anything to you. Maybe a cold drink is set down and a drop condensation from the cup flys off.

Liquid damage to the USB-C ports on the Apple laptops is so common on the laptops within our organization that I inspect the ports on every Mac I handle. However, even inspecting these ports I will many times miss the corrosion as it can be very difficult to see unless I pull it all apart to get an unobstructed view.

The intermittent nature of external devices working may be due to how the USB-C cable is connected to the laptop. Rotating the connector of the USB-C cable 180 degrees upside down can sometimes make a difference between a device working or not working if the USB-C port is partially damaged or half bad.

The only times I've ever had to replace the I/O Boards were for liquid damage, or for the ports becoming physically worn so that the cables were getting too loose to stay in place (worn ports are only an issue with the 2016 & 2017 models).

Juedne wrote:

previous models overheated insanely, but I thought this one had solved that problem. However it's started running hotter and hotter even when untaxed, despite elevation above desk and fan beneath.

The Intel USB-C Apple laptops run hot...the cooling system is designed to keep the laptop at 80C - 90C as much as possible when under load. Depending on the pins affected on the USB-C port, it is possible the damaged ports could be affecting the behavior of the laptop. If you are not actively working on anything and it is hot with the fans running at higher speeds, then it likely indicates a software issue of some sort, most likely third party software. You can run EtreCheck and post the report here for the contributors to examine to see if we notice anything which would cause your Mac to work harder than normal when idle.

Make sure to disconnect all external devices in case one of them is causing a problem. With known bad USB-C ports, an external device could potentially cause a problem with the laptop where it may cause macOS to work harder.

I'm now wondering whether the overheating could soften the pins to the extent that they can't handle normal plugging / unplugging?

No the laptop won't get hot enough to soften anything on the ports.

My concern isn't just how I got here, it's prevention and not having to repeat monumental hassle of being without a computer for two weeks while it's repaired.

Completely understandable as I am the same way even with client systems, but sometimes you may never know.

A couple of times I have seen burnt contacts on the USB-C ports, but that has been extremely rare. That could still have been started by a drop of liquid, or some tiny conductive item got stuck in the port or inside the cable connector, or it could have been from a faulty cable or external device, or possibly even a faulty Logic Board.

The I/O Boards on these laptops are usually very simple with no circuitry except for the wires & contacts...so there is very little to fail naturally with the I/O Boards.

It is possible that seeing the damage it can be determined if liquid was definitely involved by seeing either liquid residue or corrosion, otherwise it is hard to say what caused the problem except that it was most likely from an external source.

I'm just someone who has supported our organization's thousands of Macs for over 20 years so I have seen & learned quite a lot in that time. If you were not source, then you will likely never know unless years later someone makes a comment about it and you suddenly make the connection to your laptop. Take my two cents as you will. Just thought I would provide insight from the other side.

Apple has only two boxes to check:

[_] defects in materials or workmanship, covered by warranty

[_] OTHER, including accidental damage

checking OTHER is not an accusation, it simply says yours is not a defect in materials or workmanship.

Electro-mechanical devices fail at random, arbitrary, and capricious times. 

The most frequent reason for most failures is 'just because'.

Your specific failure is most likely caused by an advanced scientific principle called ...

... 'bad luck'.

--------

If you want a really substantial lesson how this this works (or more precisely how this stops working) own an older used automobile.

--------

If I could put all that history behind me for only £79 and have Apple stand behind that repair, I would take it in a heartbeat. You will likely receive a remanufactured or new mainboard.

Remember that your DRIVE (and all its files) will NOT be returned to you if they replace your mainboard. You attest that you have all the backups you desire when you submit your Mac for service.

Tiny conductive item can be anything from anywhere. I've seen so much stuff over the years from staples, to metal shavings, to even insects shorting out a circuit. Like I said, seeing the damaged part could possibly tell you.

EtreCheck will just give us information about the software running at lower levels inside macOS which typically will be the apps which tend to cause problems. Plus it will show some performance statistics and summaries of some system logs which may also contain clues.

As for monitoring the temperatures and fan speeds of a Mac, it really doesn't make sense since the laptop will do its best to maintain the system at the level Apple designed. If the cooling system is incapable of keeping the system temps within that range, then the CPU will become throttled to idle speeds until the cooling system can get the system back into a safe operating range. The only reason for seeing this information is to understand how the system meant to work or for hardware troubleshooting purposes for repair techs. MacsFanControl is the app I use when I am monitoring the cooling system when troubleshooting potential hardware issues. Most times I don't even need it now that I have an understanding of how a Mac's cooling system works.

HWTech wrote:

As for monitoring the temperatures and fan speeds of a Mac, it really doesn't make sense since the laptop will do its best to maintain the system at the level Apple designed. If the cooling system is incapable of keeping the system temps within that range, then the CPU will become throttled to idle speeds until the cooling system can get the system back into a safe operating range. The only reason for seeing this information is to understand how the system meant to work or for hardware troubleshooting purposes for repair techs. MacsFanControl is the app I use when I am monitoring the cooling system when troubleshooting potential hardware issues. Most times I don't even need it now that I have an understanding of how a Mac's cooling system works.

I've experienced an sudden thermal shutdown. Wasn't a good thing. The fans were on full blast when it just went completely dead and wouldn't restart for a minute. And when it restarted the battery was reporting negative capacity.

Doesn’t matter if it’s wear and tear, accidental, or a design defect. The warranty is only one year.

I’m surprised the repair cost was that reasonable. I remember when a USB port failure on a Mac meant a complete logic board replacement from Apple since the ports weren’t modular and were soldered directly on the board.

it is possible that it is accumulating dust inside, but any service will include cleaning out accumulated dust.

Since about 2016, SSD drive components have been soldered to the mainboard for maximum reliability. Apple determined that more problems were CAUSED by sockets that were SOLVED by sockets. Once they could buy drive components that were reliable enough, they soldered them in place for trouble-free operation.

There's no way we can tell you about physical damage over the Internet. Get it to Apple for evaluation.