Don't use magnetic USB-C cables

I bought one of those magnetic USB-C cables and nearly fried something in my laptop with static electricity on the exposed plug.
The laptop failed to post, and the blinkenlights indicated a memory failure with error code 00001110.
The next day, it booted fine, which was odd. Memory tests indicate no issues.

warning symptoms that you are about to fry something: the display will glitch or suddenly turn black during use.
solution is to remove the USB-C cable and it’s detachable plug from the laptop.

Of course there are a few threads here about magnetic USB-C cables and in them, they do warn you not to use them, but I didn’t realize it was an issue until it was too late.

2 Likes

Part of the problem might be that people have seen or heard of apple’s magnetic connector. So they think that it should work fine with usb. Well, no. Apple’s magnetic connector was designed from the ground up for that purpose. Whereas USB was never made to handle the issues that such a connector brings. So it can damage or kill your devices. Just a matter of luck. Don’t use magnetic USB, unless you’re fine with the idea that your ports or whole mainboard can die at random.

4 Likes

Not sure if that fully resolves the issue, but I did modify the magnetic charger design so that instead of a usb-c extender there’s a “data blocker” inside, so that physically there are only the voltage, CC and ground wires connected. It does limit the card to only charge, but I wouldn’t want to send 10-40Gb/s through a wobbly connector to begin with.

Might not fully resolve the problem, but it’s certainly far better.

Having tested several of those connectors and used one for more than a year, I dare to say: a warning might be justified, but along the lines of: I you buy such a thing, don’t be cheap. If the adapter costs less than 15€ and does not use gold plated contacts, stay away. Also, the better ones usually do not use pogo pin type contacts but some kind of contact bar.

I have, however, used high quality magnetic connectors between my dock and the FW13 for months with much success and no problems at all. At least full 20GBit USB is no problem (Tested with two external nvme enclosures). I did not yet test full Thunderbolt 40GBit yet, because TB hardware is quite expensive and I had no explicit needs for it so far.

I have attached some pictures of a good one.




2 Likes

The USB-C subreddit strongly advises against any magnetic adapters. But the Apple Magsafe 3 is usb-c on one side at least.

I think the problem is that all the affordable magnetic adapters you find on Amazon are not putting in the real expensive engineering needed to make it work safely and reliably … and if they did, how would you know, you’d probably pick another brand that looks the same but is cheaper.

I have a cheap third-party usb-c magsafe-2 cable from amazon, because I wasn’t going to buy another Apple magsafe-2 adapter (where the cable is permanently attached to the brick, and when it inevitably frays, the whole brick is e-waste). I’ve used it for a couple years on an old personal laptop, it works. But I have seen it arc a few times when the connector comes in askew. You can also easily tell that it behaves a bit different, the green led is instant, while on the real adapter it takes 1 second for it to come on.

My theory: Apple makes sure the voltage/current are not high during connect (and maybe disconnect as well? fast hardware detect?). Even though magsafe-3, while usb-c on the adapter side, is probably not usb at all on the laptop side, I think it’s possible for third-party adapters to make something similar, where there is a logic chip in each side of the adapter, which participates in the power negotiation, and ensures it does not flow during connect (and disconnect?). But that’s a lot more complicated, and I assume no third-party magnetic adapters do this. Would be cool to find one that did …