Leopold FC660MBT USB C-to-C not working, but C-to-A works?


I hope it is okay to ask this kind of question here.

I am the happy owner of a Leopold FC660MBT (bluetooth and USB C). It works well with bluetooth but I am a bit tired of having to buy and switch batteries when I could just keep it connected to my computer.

So I bought a USB C cable (C on both ends), which clearly states “Data and Power cable (PD)”, and tested it on the two USB C ports of my two computers but it does not work: no LED / light on the keyboard, no device recognized on Windows, typing does not work.

Now if I use a USB C to USB A cable (like, the good old rectangle-shaped “original USB”), it works.

Any idea what could be going wrong?

I saw Leopold keyboards being mentioned here and there on this forum. Do your Leopold keyboards have the same issue?

Any guesses on how I could fix it?

Or is it just because Leopold chose a shitty controller that’s only compatible with USB A ports on the host side and the only way out is to mod the keyboard by replacing the controller?

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This happens for me, and I have a couple of different keyboards where this is the case (C-to-A is the only thing that works).

Skimming around—here’s a representative reddit thread with some discussion (grain of salt etc)—it seems to be something about the device manufacturer (keyboard PCB in this case) cheaping out on a resistor in the USB-C connector. So a C-C won’t activate because the power-side (your computer) isn’t seeing the right things from the keyboard side, but A-C is less picky and works fine.

I’ve worked around it two ways.

1: just using a C-A cable if you have the A port anyway.

2: If you only have a C port available, I’ve had success with a C-A cable, then using a female-A-to-male-C adapter. Even though that’s a pointlessly circuitous C-C in the end, it seemed to work for me.

YMMV of course. Good luck!

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I think @unexplainedbacn explained it pretty well (fault with the PCB) but I just wanted to add one option:

This was pretty common 4-5 years ago when we started getting the first USB-C custom keyboards but has thankfully gotten better. Back then some of the custom cable makers (I’m thinking of Zap! in particular) would make USB C-to-C cables that emulated the Host-Device model. The only drawback was that these cables were not ambidextrous (or side agnostic) you had to make sure you plugged the host side into the host and the device side into the keyboard.

Zap! is, unfortunately, no longer doing business but if you reached out to some other cable makers they might be able to tell you if they use a similar cable making method. Most of them are fairly small shops and will work with buyers. I unfortunately am out of the loop on the best custom cable makers these days but someone else here might chime in.

Good luck!

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Yes I just got an answer from the manufacturer and they say on this model the board only works with USB A although it’s a USB C female port, and I would need to change the board for it to work.

Thanks for your explanations guys.

The custom cable sounds like a nifty solution, I need to look for someone who could make it for me. Or maybe just by adapters as proposed by @unexplainedbacn.