Updating old USB connectors

From Mini-USB and Micro-USB to USB-C

I still have my old CanoScan LiDE 200 scanner. I'm using it only very rarely, but if I do, it annoyed me to also need to use an old Mini-USB cable for it.

I bought some USB-C connectors and decided to try to switch the device connector. The USB-C connectors still have the original USB data and voltage lines. I hadn't even realised that the legacy Mini- and Micro-USB connectors have one extra pin. It was never used for practically anything. Therefore, just connect the two data lines, the voltage pin and ground and everything should work.

This was a straightforward process of taking apart the device, soldering off the old connector and switching in the USB-C connector. The only problem I had was with the very delicate wires from the circuit board to the connector. At first one of the contacts broke off but I decided to solder in some wires instead and with that, everything works. I enlarged the connector port hole in the case a bit and hot-glued everything in place. The end result works great with a USB-A to USB-C cable.

The catch

There's one catch, though. I need to use a USB-A to USB-C cable so that the device gets power, so USB-C to USB-C does not work. The USB-C connectors have a couple of signal pins that detect what kind of device is connected. In pin out diagrams these are called CC1 and CC2. Before the pins give some information, a USB-C port doesn't give any power, unlike a USB-A port which provides 500 mA of current by default. Unfortunately I didn't realize this before gluing in the whole connector to my old scanner.

I also have a bunch of other devices that use Micro-USB for charging, e.g. my bicycle lights. It would be nice to be able to charge those from a USB-C port also, using the same USB-C to USB-C cable I use to charge all my devices, with just a Micro-USB to USB-C adapter.

In addition, it's not just old Micro-USB devices that need charging - I also have some devices with USB-C port for charging, but they still require a USB-A to USB-C cable. For example I have a lint remover like that, and I made an adapter for my Remington electric shaver to use USB-C.

Universal USB-C to dummy devices adapter

So, after realizing how USB-C actually works, I also created an adapter from USB-C jack to USB-C plug so that one of the CC pins is grounded through a 4.7 kΩ resistor. Apparently the USB specifications say 5.1 kΩ is the optimal, but there are huge tolerances (I think around 25% or so) so 4.7 kΩ works just fine. The adapter works only one way, though, since the connectors didn't have enough space to solder another resistor to the other CC pin, which I instead cut off completely. In any case, the standard USB signal lines, voltage and ground are connected normally.

Now my devices also work and charge with a USB-C to USB-C cable, if I just use the custom adapter in correct orientation with the cable. For devices you modify, it might be worth doing the resistor trick for both CC pins while swapping in the new USB-C port. This way, no dummy device adapter would be needed. Back when I did the scanner mod some years ago I didn't know this, but now you know.