Chord Mojo Bluetooth Receiver

I have recently purchased a 2nd hand Chord Mojo and for me, it sounded great and definitely an upgrade over my Galaxy Note 9 3.5mm jack.

However, there are 2 major complaints/issues that I have with Chord Mojo:

• The lack of Bluetooth receiver function. It requires Chord Mojo to be always connected through wire to either my Android phone or my PC/Laptop.
• The use of Micro USB port that is outdated for the DAC and charging. All my other device charge through USB C.

In this article, I will share how I upgraded my Chord Mojo to solve both my Bluetooth receiver and Micro USB port problem.

While searching for how others connect their audio source to the Chord Mojo, I came across this article about connecting Chord Mojo to an XDuoo 05BL Pro Bluetooth receiver (link). The XDuoo 05BL Pro is basically a Bluetooth receiver that for XDuoo XD05 Basic or XD05 Plus to add a Bluetooth function to the DAC. The output of this Bluetooth receiver is coaxial which is also supported by Chord Mojo.

So, I purchased a XDuoo 05BL Pro, dissemble it, and study how the PCB is connected to the battery, the buttons, etc. My plan is to design a new casing to fit this Bluetooth receiver and 3D Print it to be used with my Mojo.

As for the 2nd problem, I found this Micro USB to USB C adapter from UGreen that is suitable for my application.

I’ve also tested that they do receive audio from Android phones through Bluetooth LDAC and output the sound at Chord Mojo.

There are a total of 2 Micro USB ports on Chord Mojo, one is to charge the device, another one is for the USB DAC functionality. The modification that I did is:

• to connect the Micro USB to USB C adapter to the DAC Port to “convert” it to USB-C
• to connect a Micro USB cable to the Charging port and wire the +ve and -ve line to the Bluetooth Receiver 5V supply for the charging

This way the end result is that I will have 2x USB C ports, one for the USB DAC function of the Mojo, and one for charging both the Bluetooth receiver and the Mojo.

For the charging Micro USB Cable, I sacrifice one Micro USB cable, hack into the Micro USB Port to remove its plastic casing, and get access to the USB 4 wire.

Normally USB cable has 4 wires with the colours Red, Black, Green, and White. Red and Black is normally the 5V supply and Green and white is the data cable. Connect the Red and Black wire to the 5V supply on the Bluetooth receiver. By using multimeter I found the 5V Capacitor as shown in the image below:

After wiring the Micro USB Port, I test the charging by connecting the charger to the Bluetooth Receiver’s USB Port and connecting this Micro USB Port to Chord Mojo. Both device can be charge by the USB C port on the Bluetooth receiver.

Now that all the electrical and wiring is complete, I work on the design of the casing. It consist of two part, top and bottom. I also re-use the original buttons from the Bluetooth receiver, and the dimensions from the original Bluetooth receiver’s casing helps in the design. You can download the CAD file for the casing design at the end of this article. Do provide your suggestion and feedback on any improvement to the CAD design at the comment section.

The top casing will house the Bluetooth receiver PCB and Battery, and the original buttons. The side that match to the Mojo also has been shape accordingly to match Mojo dimensions.

The bottom casing will be the ports attachment to the Mojo. The coaxial 3.5mm port, and 2x Micro USB port will be mounted on the bottom casing.

For the top casing, take note that you will need to place the antenna at the bottom of the PCB, the antenna will be the first part to be adhesive onto the casing, before screw in the PCB.

For the bottom casing, the Coaxial port is screwed to the bottom casing, and the both the Micro USB adapter and Micro USB charging port connected.

I uses hot glue to secure both the USB port in the right position. The Bottom casing is attached to Mojo for the whole glueing process to hold the both USB port to the right position.

After the glue harden, it create a fixed micro USB port for this Bluetooth Adapter for Mojo. I uses double sided tape to secure both the top and bottom casing, and also transparent tape to wrap around them

I am very happy with the outcome of this project, and it really give the Mojo both the Bluetooth receiving function and USB C port for the DAC. The Bluetooth receiver also by default already provide the media control button which really improve the experience. I can now leave my Android phone in my pocket and navigate through the playlist using only the upgraded Mojo.

You are welcome to download the CAD file below, and do give your comment and suggestion for this project.