Adding an Audio Jack to a MUJI Wall CD Player

The MUJI wall-mounted cd player is a nice piece of minimalist Japanese design (it got added to the permanent collection of the museum of Modern Art in New York in 2005).

It has one problem though: the internal loudspeakers are of very bad quality and it's not possible to use it with externals speakers because of a missing audio jack. However it's very easy to add one. This instructable will show you how.

What You Will Need

a female 3.5mm stereo audio jack with switch contacts (normally closed)
soldering iron and some wire
a mini drill or dremel

Open the Cd Player Case

Remove the 4 screws on the back of the cd player. Open the case and remove the on/off switch as well as the power connector. You'll find that the two speakers are connected with a 4 pin plug towards the bottom of the player. The two black cables are ground, red is right channel, white is left channel.

You'll need to desolder/cut the red and white cables from the speaker and additionally one ground cable (on the photo I picked the one connected to the right speaker).

Make Space for the Audio Jack

I used a dremel to widen the slot so that the 3.5mm jack fits through the slot. You probably have to experiment, or you could just use a drill with an appropriate bit. A 2.5mm jack might fit without drilling, but I haven't tried that.

If you don't want to drill the case or prefer a single cable for aesthetic reasons you can also try to use a 4-pin cable which combines power and the audio signal, see the comments further down for more details.

Solder the Cables and Fit the Jack

Solder the wires you removed from the loudspeakers to the audio jack. There're usually 5 pins on it: 1x ground, 2x left channel and 2x right channel. Make sure you solder the cables to the pin which is connected to an inserted plug (test it with a 3.5mm solderable plug and make sure you get the polarities (L/R) right). The 2 other pins need to be soldered back to the speakers and will only be active when no plug in inserted (= normally closed). Solder the black cable from step 2 to the ground pin on the jack, and another back to the speaker's ground.

That's It!

Before closing the case make sure that the audio jack is sitting nicely in the slot and that everything works. Dont forget to reconnect the on/off switch as well as the power plug. It should work like a normal laptop audio jack: an inserted plug turns the loudspeakers off.