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Today I'm doing a USB cable test.
I have quite a few to go through

ahh, one of those famous three-wire USB cables.
GND, VBUS, and D+ are connected, D- isn't. I'm sure that'll work fine

also this tester can tell if a USB-C cable is inserted upside down or not.
I kinda hate having this ability

also I'm using this device in the CR2032-powered 3v configuration, right?

I own at least one cable that works at 5v but doesn't at 3.3v... because it has some smarts in it, and they don't run at 3.3v

Fun fact: Power-only USB cables are like bees, they leave their stinger behind when they sting you

ooh, nasty: I found a USB-C cable that consistently has a disconnected D+ in one orientation, and intermittently in the other orientation.

So it only works <50% of the time. Nasty.

I decided to cut out the middleman and test all my USB extender cables at once.

Good news: all eight of them work.

okay all "normal" cables tested. I'm now into the realm of tricky ones this can't test directly.

things like male-to-male micro-usb.

why?

and the frankly surprising number of cables I own which have more than 2 ends.

usually they're like usb 3.0 micro B to usb A and an additional power-only usb A, but sometimes they're like USB A to usb mini to usb A female

that one has all the data pins connected, so unlike the usual kind of 3-end connectors which are just there to get some extra power for external devices, this one will break a lot if you connect all three ends

I still need to do that for an AC power cable.

like, people are always saying you should never make a male-to-male power cable... but no one ever said I shouldn't make a male-to-male-to-male cable!

how do I test a male micro to male micro cable?

yeah I don't think I have any way to test this.

wait! I got it.

I have a micro-usb to usb-c adapter. slip that on the end, and now it's a USB-c to micro-usb cable.

okay so it seems that the way this device works means that it's always going to run something like 0.5v across the cables. So no matter how I power it, cr2032 or VIN, it can't test my couple of cables that need +5v

For example, this micro-USB cable that has LEDs in it to show when it's connected.

Or these USB A to micro connectors, which are supposed to be switchable between power-only and data+power.

ONE of them works, the other doesn't. It only does power, and windows throws up a "USB device malfunctioned" error when you try to switch it to data mode

(unfortunately when I connected them both for the picture, I forgot which was which)

okay all done. Let's see the count:
1 power-only mini-usb cable
1 power-only USB-C cable
4 bad cables
3 magneticly attached cables I'm throwing away because I have lost the other half

TWENTY FUCKING SEVEN power-only micro-USB cables.

All have been beheaded and can now be thrown away.

and one cable has defeated me:

lightning to micro-USB.

Normally I could do the same trick I did with the micro-micro cable, but in this case, the cable is too short for that. Since I don't have any USB-C or micro extension cables, I can't make it reach

my wife randomly found a cable in the bedroom, and I ran off with it to stick on the tester. Guess what? It's a USB-C charge only cable!

We must stay ever vigilant, the threat never ends.

William D. Jones

@foone Why does the cable checker need a battery? In case both sides are dead?

@cr1901 if it didn't have a battery, how would it light the LEDs? the cable is plugged into the device at both ends, there's nowhere else for it to get power

@foone Ahhh, see I fundamentally didn't understand how this tester works :D!