Bluetooth headsets for motorcycles are expensive. Nokia BH-503s are cheap. Moreso for the knockoffs. This instructable will show you how to rewire a Nokia BH-503 for use with a universal motorcycle helmet.
Step 1: Disassemble
First thing's first. Take out all the screws and keep them safe for future use. Each side of the BH-503 has 3 main screws wight under the foam covers. After taking them out, the speakers, battery, and PCB should be in plain sight.
Step 2: Note the Connections
the BH-503 PCB is pretty straightforward. the terminals for Battery, Speaker, and Mic are labelled here. in case yours aren't, it's as simple as following where the wires lead to. Take pictures of your wiring before desoldering so you can avoid errors later on.
Step 3: Separate the Parts
What we want to do is basically extend the wires of both speakers and the mic so we can place them in the helmet while attaching the controls and battery outside for easy access. You also might want to cover your speakers with hard plastic, since the membrane is very soft and fragile.
Step 4: Combine Controls and Battery
The battery is located on the left earpiece, while the controls are on the right earpiece. Since we are taking out the speakers, it is now possible to combine the battery and controls in the same housing. For the battery, use the space left off from taking out the right speaker. Solder the battery terminals to the PCB and test if it lights up.
Step 5: Measure and Fit to Your Helmet
After attaching the battery, it's now time to rewire and resolder both speakers. I decided to attach the control housing on the left side of the helmet for easier access during rides. This meant that I would have to use a shorter cord for the left speaker than for the right speaker. Measure the length of each side and cut your wires. some slack is ok, but making it too short results in a waste of some time, effort, and materials. Do the same for the mic. Fortunately for me LS2 helmets already have a provision for small speakers in the helmet, so there was no need for me to tinker with the inside.
Step 6: Clean Up and Reassemble Everything
The last step involves cleaning up. The connections are still fragile at this point. I used ho glue to set the wire insulation to the control housing so the solder points don't get stressed during use. I also put some velcro tape on the surface of the helmet and the back of the control panel so I could easily take it out when the helmet needs cleaning, or I want to use the headset on another helmet.
Step 7: Test Your Work
Power up your unit and pair it with your phone. If it works, congratulations, you can now enjoy music and voice calls on the go!