Only 2/3 USB ports on my MB Pro are reversible

[snail22]

For a while it seemed like a crapshoot trying to get my MB Pro (14" M1 Max) to recognize one of my various external drives. Finally I discovered a predictable pattern: the USB port on the right will only work when the cable is plugged in "right-side up" (which I didn't think was a thing with USB-C but clearly it is). The two ports on the left accept the cable plugged in either way.

I've tested this with 3 different drives and 3 different cables and this behavior is consistent. Not a huge pain now that I know how it works, but is this normal? I was under the impression that a) all three USB ports on my MB were identical and b) USBC cables can be plugged in either way.

 

[lcubed]

time to use AppleCare to replace/repair that port

 

[Basic75]

You tried 3 drives and 3 cables, but have you tried 3 computers? If not, please don't peddle your experience with 1 single defective computer as how things generally are.

 

[snail22]

You tried 3 drives and 3 cables, but have you tried 3 computers? If not, please don't peddle your experience with 1 single defective computer as how things generally are.

A little touchy are we? I think you misinterpreted my thread title so I modified it.

 

[BanditoB]

Hopefully @Basic75 will chill out a bit.

No, your experience with the ports is not normal. The cable should be able to be plugged in either way and should work the same. Time to make a Genius appointment and take all your equipment and cables in to verify what’s going on.

Good luck!

 

[mr_roboto]

For a while it seemed like a crapshoot trying to get my MB Pro (14" M1 Max) to recognize one of my various external drives. Finally I discovered a predictable pattern: the USB port on the right will only work when the cable is plugged in "right-side up" (which I didn't think was a thing with USB-C but clearly it is). The two ports on the left accept the cable plugged in either way.

I've tested this with 3 different drives and 3 different cables and this behavior is consistent. Not a huge pain now that I know how it works, but is this normal? I was under the impression that a) all three USB ports on my MB were identical and b) USBC cables can be plugged in either way.

(b) is correct, a fully functioning USB-C port shouldn't care. Like others said, definitely get it serviced.

I just wanted to explain that the way USB-C supports this suggests what's happening.

USB-C takes advantage of the connector's symmetry. There are four differential pairs of conductors for high speed data transfer, two on each side of the "tongue" inside the computer side port:

TX1+/TX1-      RX2-/RX2+
========================
RX1+/RX1-      TX2-/TX2+

A basic 5 Gbps USB3 connection uses just the TX1 and RX1 pairs (tx = transmit ie outgoing data, rx = receive or incoming data). 10 Gbps uses all pairs. If the cable between the two devices is "twisted" (plugged in a different orientation on one end), the cable effectively swaps the TX1 pair with the TX2 pair, and the RX1 pair with the RX2 pair. The USB-C host port is supposed to deal with this by detecting the swap and using silicon based muxing to correct it.

However, let's say you have a port where at least one of the pins on one side of the tongue isn't able to make contact - there's a piece of debris in there, or the pin broke off, or something. You plug in a 5 Gbps USB-C peripheral. You'll be fine as long as the cable rotation puts the active signals on the side that's good, but not fine if it's on the other side.

 

[Argon_]

time to use AppleCare to replace/repair that port

The USB-C ports are modular, thankfully. A fried HDMI port would require replacement of the board, which I doubt anyone would actually do.

 

[StudioMacs]

A little touchy are we? I think you misinterpreted my thread title so I modified it.

I don‘t know how common this is with USB-C type port, but have you checked to make sure there isn’t a price of lint or debris in there that might be blocking part of the port?

 

[snail22]

Thanks for clarifying that this is definitely a defect. Made my Genius Bar appt and hopefully it's not more trouble than it's worth to get repaired.

 

[Paradoxally]

I don‘t know how common this is with USB-C type port, but have you checked to make sure there isn’t a price of lint or debris in there that might be blocking part of the port?

If that were the case the port wouldn't work at all or fail intermittently.

 

[anotherscotsman]

For a while it seemed like a crapshoot trying to get my MB Pro (14" M1 Max) to recognize one of my various external drives. Finally I discovered a predictable pattern: the USB port on the right will only work when the cable is plugged in "right-side up" (which I didn't think was a thing with USB-C but clearly it is). The two ports on the left accept the cable plugged in either way.

I've tested this with 3 different drives and 3 different cables and this behavior is consistent. Not a huge pain now that I know how it works, but is this normal? I was under the impression that a) all three USB ports on my MB were identical and b) USBC cables can be plugged in either way.

Same thing has happened to me - even the same port! Did you get this resolved? If so, how? Thanks

 

[snail22]

Same thing has happened to me - even the same port! Did you get this resolved? If so, how? Thanks

Took it in to the Apple Store for a repair. They were pretty quick... I got it back in less than a week. Definitely a hardware defect.

 

[anotherscotsman]

Took it in to the Apple Store for a repair. They were pretty quick... I got it back in less than a week. Definitely a hardware defect.

Thanks for that - I’ll follow your lead.