Wednesday, 24 July 2019

WARNING! Don't buy this 'BAD USB' cable from Amazon - it could start a fire!

I purchased this USB cable from Amazon yesterday for use in the car with my smartphone.

TECHGEAR: USB C Cable, 30cm USB Type C 90 Degree Right Angle Sync & Fast Charge Reversible Cable

I was intrigued by the 'reversible' design of the USB 2.0 connector as well as the right-angle connectors. I have never seen a USB Type-A male connector with a set of contacts on each side and I wondered how it worked...

So today I used it to connect my phone (a Moto G7) to the USB socket of my new VW Golf, but the Golf console failed to detect that any USB device was connected to it!

So I disconnected the phone from the cable but left the USB 2.0 cable connected to the car's USB port.

After driving back home from the supermarket, I went to unplug the USB 2.0 connector from the car in order to test it...
and nearly burnt my fingers on it because it was really hot!

It had obviously been shorting out the USB 5V rail and it was lucky that it hadn't blown a fuse in the car or melted and caught fire!

I tested the cable and there was NO SHORT when it was not connected to anything, but then I  connected it to the USB 2.0 socket of a USB cable.

I only pushed it in half-way so that the contacts would be easily visible and took some pictures of both sides of the connector - and I couldn't believe what I was seeing....

The four contacts touch the USB socket contacts on this side no problem, but...
Two of the four contacts on the other side short out on the metal casing!
Pins 1 and 4 (5V and ground) and are shorted out by the springs! Since the metal shroud should be ground, if the 5V contact touched the metal spring tensioner then we have a dead short!

QED -  a short just by plugging it in to a USB socket!
I have not used it in any of my computers because I am afraid it might damage them or start a fire!

This must win the award for the stupidest design of 2019! It obviously only works if you plug it into a USB socket that has plastic shrouding and no or weak metal springs or are just lucky!

An old, well-used USB socket may work OK because at least one of the two metal springs will probably not touch one of the two USB power contacts (or at least the 5V contact won't touch the spring), but a new USB socket with strong spring tensioners (like in my new car) may well short out the power!

It was only £3 so it's going in the bin!

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