Step 2: Cleaning up the PCB
Remove the hot glue covering the solder connections on the PCB. While pulling gently on the cabling, heat the solder joints one-by-one with a tinned soldering iron until they pull loose. Remove the speakers from their plastic holders. Desolder the speakers and the microphones loose from their wiring.
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You should now have the following components: PCB, battery holder, 3.5mm jack, 2 microphones, and two speakers. Using a soldering iron and solder sucker (and soldering wick or whatever desoldering tools you prefer, clear out the holes in the PCB where the wiring was attached. This will allow you to pass the wire through before soldering, giving you a sturdier connection than the factory wiring.
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Step 3: Preparing the microphones and Speakers
Now that we have the PCB cleaned up we’re going to estimate the length of our wiring. The first thing we’re going to do is decide on a location for our microphones. You want one on either side of the helmet in a location where it won’t be too obvious. On my MK VII (produced by EVAKura if you are looking to source the same helmet), I chose a spot right behind the visor where the helmet was going to be painted black. Take into consideration that you will need to access this location from inside the helmet to insert the microphone. Carefully drill a hole matching the diameter of the microphone.
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Next, decide where you would like to mount the PCB. From this location, unroll some wire and run it to one of your mic locations, leaving a little extra, and cut. Measure some wire of a different color to the same length and cut. We used red for positive and black for negative, but the idea here is to differentiate positive and negative, so any two colors will do. For a clean look, chuck these wires into a drill and twist them together. If you do so, leave some additional length as the wires will shorten as they twist together.
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On the back of one electret microphone, solder your negative wire to the pad with traces running to the outer ring and your positive wire to the semicircular pad beside it.
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Repeat this process for the second microphone.
In the same manner as the microphones, cut one set of wire for each speaker. It doesn’t matter which pads you use for positive and negative, so long as you are consistent from speaker to speaker. Otherwise, they will be out of phase (it’ll sound weird, trust me).
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Cont.