Makita DMR104 Bluetooth Mod

Makita DMR104 Radio's lack bluetooth functionality, I have seen a few people modify them to have bluetooth but they go crazy drilling and cutting the case to suit their needs. my option costs around £5, only basic soldering skills needed and there is an option to not even have to drill holes for buttons if you don't want to do this. The bass isn't AS loud compared to a direct connection in, or the radio, but it works just fine and is loud and clear enough. You could buy a more expensive module if you want it to have better booming sound but the LN BT02 usually comes with all the cables you need to connect and the board is clearly labelled as well which helps a novice understand which wires go where.

Supplies

LN BT02 Bluetooth Module

Soldering Iron

Long philips screwdriver

Hot glue

Small plastic rod

(optional)

Drill

1cm long tactile switch x3

Step 1: Unscrewing the Back

Unscrew the two screws at the back using a long philips screwdriver

Step 2: Unscrewing the Front

Unscrew the 4 allen bolts located on the front

Step 3: The LN BT02 Module

The LN BT02 Bluetooth module, costs around £5, it is perfect for this project. I am going to only take the power off of the 12v in as I didn't want to mess around with the battery power (the battery is 18v, but needs to be converted through the board found at the centre (2nd picture), there are two separate inputs for two different battery types.

In theory you could connect a 18v to 12v stepdown transformer to this board, but I didn't know much about this to do it safely and not cause any interference in the audio signal but I welcome any comments on how to do this and perhaps I can add this step in the future.

So it's important to know that this mod will only work when wired up the way I have done it if you power it with the 12v adapter, it won't give power to the bluetooth module via battery unfortunately.

The module is perfect for this as it came with the cables needed and all cut and ready to go and are the perfect length.

You only need the connection for the audio out and the 7 to 24v power connector.

Step 4: Tapping in the 12v

Wire the bluetooth modules power (NOT the 5v one) the 7 to 24v power input, take a feed off of the positive and negative pins of the 12v power in located on a board screwed to the front panel of the radio.

Step 5: Wiring Up the Audio

Wire the audio out wires to the AUX 2 jack, the jack is secured by two screws, unscrew it and you can see the connections. They are even labelled on the board L D G R. The colours are not the same except for Ground, but you could be supplied with any colours, so just make sure you follow the labels for each wire from the LN BT02 board to this little board with the jack connected to it. L to L, ground to ground and R to R.

Thats all the connections done! Now you should be able to power it when connecting the 12v power adapter, pair it with your phone. You only need to follow some more steps to finish the mod.

Step 6: Hot Glue the Board

Hot glue the boar to the inside base of the radio, or use a sticky pad. I used both a foam sticky pad and hot glued the sides. The provided cables should just be the perfect length

Step 7: Activating the AUX 2 Jack

The audio jack needs to be plugged in using a small plastic rod of some sort (I used a lego one). Instead of soldering the jack to be permanently on, I used this plastic rod to activate the audio with the radio unit, with nothing plugged in when you press "BAND" AUX 2 will not show up, you need to have something plugged in to activate the switch inside of the audio jack for the radio to see you are using aux 2. I didn't solder or bridge any connections to keep it simple. A plastic rod like this is ideal.

With the plastic rod inserted, AUX 2 is activated and you will be hearing the sound of your paired bluetooth device when you select AUX 2 on the radio.

Step 8: Adding Buttons

If you are happy with just having bluetooth in the radio and thats it, you can go ahead and close it all up and it's job done! This bluetooth module automatically goes into pairing mode when powering on (you don't need to press a button to pair) so it's an easy mod to do for a beginner with basic soldering skills, also notice how there was no drilling or anything needed and if you wanted to remove the mod completely just desolder it from the pins you had connected it to.

But if you did want buttons, the module comes with a small group of buttons attached to a pcb that can be separated if you wished to have them in different locations.

The provided buttons are small however so I desoldered them and added the same kind of buttons but with longer buttons to them.

Step 9: Drilling Holes

I drilled 3 small holes at the front for the buttons, I have chosen to have them at the front rather than the top, the radio is splash proof so make note that any drilling to the case will make it less splash proof, if I drilled holes at the top of the case then some water may go down inside the unit, so I placed them under the control knob at the front, I could add a rubber membrane to make it splashproof again but I think it's ok for what I use it for, it's not going to be exposed to the elements as it will be powered with the adapter and not a battery as well.

The buttons just control play, back and forward. Holding forward or back increases or decreases the volume of the paired bluetooth device.

That is all the mod is really!

I hope you found it helpful to add bluetooth to these radios as they are great, hard wearing devices and be a shame to leave them bluetooth-less!

It's a shame I didn't go to the next level and have it run with the battery but I think more parts are needed and more soldering involved because the battery connection is independent of the 12v in, but is controlled by the board, and I didn't want there to be a situation where say if someone plugged in the 12v adapter AND had the battery connected as well - maybe I would have bridged two points together which shouldn't have been and caused a short or a 12v feed back into the battery ... i don't know, I just need to research into this more to see how the regulator board works.

So for now it's a bluetooth mod that runs with 12v adapter.