Makita BMR radio mod

Makita BMR radio mod

Problem-

Makita BMR radio stops working due to low quality wiring/bad design of the AC/DC adapter

Solution-

Move adapter and flimsy wiring to the interior of the radio, connect to an iec outlet and use a more durable power cord on the exterior of the radio.

Parts cost- (not including misc scrap wire, heat-shrink, solder, etc)-
IEC plug, $1.97

http://www.parts-express.com/pe/showdetl.cfm?partnumber=090-442

10′ IEC cord $4.98

http://www.parts-express.com/pe/showdetl.cfm?partnumber=110-180

My Makita BMR radio stopped working after a couple of years due to frayed wires on the original “power block”, or AC/DC adapter. The radio worked with the 18V LXT battery but not with the adapter (with the adapter plugged in the screen read the letter “E”). Upon looking more closely I realized that the adapter wires had frayed slightly and crossed. I cut and spliced the wires back together but still the adapter still didn’t work.

I did a little research and found that 1) adapter wire failure is a common problem and 2) a few people had come up with various mods for this radio, one of which addresses the crappy adapter wiring issue. (See this video http://www.youtube.com/watch?v=QoTyfYJdUz8 )

The following is an explanation with photos of how I repaired my radio and gave it a more durable cord.

Let me first say that I’m not an electrical expert- I’m a cabinetmaker. I’m offering this info because I know that the power cord/adapter failure is common and I thought it could be helpful to pass on what I’ve learned. If you have questions or constructive comments feel free to let me know. If you don’t like the radio or my modifications I honestly don’t give a crap- I don’t want to hear your opinions on how much time this took me vs my hourly rate or that my soldering skills suck. I obviously can’t guarantee this will work for you and as I said I’m not an expert… so proceed at your own risk.

In my case, the AC/DC adapter died so I had to replace it (it wasn’t just the wires either, my multimeter confirmed that was completely fried). Luckily, I had one leftover from an old netgear router that met the same specs. The basic order of the modification is this…

1) Confirm that you have a working adapter and order parts

2) Unplug, remove battery from and open radio (4 allen bolts on the front and 2 phillips screws in the back, accessed through the large battery compartment)

3) Plug working adapter into the radio and power on. Use a multimeter to confirm the polarity of the connections where we want to connect our adapter (see attached pics). Note polarity.

4) Make a note of what wires go where in the radio (in case you need to disconnect them)

5) Cut hole for and attach iec plug with screws

6) Paying attention to polarity, solder approx 6″ of scrap wires from iec plug to prongs on the AC/DC adapter (I soldered all connections with heat-shrink tubing loosely on the wires. After I confirmed that everything worked I then pushed the heat-shrink over the connections and heated it to protect the connections. Electrical tape would also work fine.).

7) Paying attention to polarity, solder wires exiting the adapter (now 12V DC power) to the bottom of the board located on the bottom back of the face of the radio (see pics).

8) Plug new cord into iec adapter and power radio on to confirm that it works. DISCONNECT POWER CORD NOW.

9) Push heat shrink into place and heat or apply electrical tape to protect connections.

10) With radio on it’s back, put adapter over black plastic “plate” located on the upper-middle back of the radio so that you still have access to the screws that hold the plate on (Sorry I didn’t get a pic of this plate before I glued the adapter in place, look at my pics and you should be able to figure out where it is). Note rough location of adapter to the plate, set adapter aside.

11) Remove the two screws holding the “plate” on and then super-glue the adapter to the plate, making sure you have access to the screws. Let the glue dry completely and then screw the plate and adapter into the radio using the existing screws and holes. (I also made a small cable strap to help make sure the adapter doesn’t come loose. I used a scrap piece of cable and ring terminals, driving the screws through the terminal rings. I don’t think this was necessary but it’s the power connection- I didn’t want to chance the adapter coming loose).

12) Reconnect any wires you may have disconnected and confirm again that the radio works. Now reattach the face of the radio and you’re done.

Separate from the power problems I decided to improve the sound of the radio. While doing the power cord/adapter mod I also added a new pair of tweeters ($2.50 each from Parts Express) with crossovers from some old surround speakers I had. At low to medium volumes in the house the tweeters produce a noticeable hiss but in the shop and at higher volumes the radio sounds much better- it’s especially noticeable in the shop where the higher frequencies make for clearer sound in the mid-range-heavy din produced by my tools, dust collector and air cleaner.

Thanks to Greg Di / vadgegd for posting the original mod video that allowed me to fix my own radio and consequently post this for you.