Over the years, we've gotten countless questions regarding instructions for replacing the microphone on the Bose A20 aviation headset. Replacing the microphone is a fairly easy process that can be accomplished within 5 to 10 minutes.
There are many reasons why a pilot may choose to replace the microphone on the Bose A20. The most common reason is due to a damaged microphone or faulty connection caused by a break in the microphone cable due to years of rotating the mic boom. Another reason a pilot may wish to replace the microphone could be that they want to switch from a low impedance 5 Ohms mic (commonly found on the military version of A20 with the U174 helicopter plug) to a high impedance electret mic so that the headset can be used in a G/A aircraft. If the reason is the latter, and the headset will be used in an aircraft with a G/A dual plug connection, then an adapter, such as the U174 to GA Adapter will also be needed.
To get started, all you need is a small Phillips-head screwdriver such as a #1 and a replacement microphone such as the Bose OEM Electret microphone.
Step 1: Detach the down cable
The first step is to remove the headset cable assembly (down cable module) from the headset. This will make the process much easier. This is accomplished by removing the two screws that secure the cable assembly to the headset.
Step 2: Remove the housing cover
Once the cable assembly has been removed, you can now disassemble the microphone housing assembly and remove the cover. Again, just two screws.
Step 3: Unplug the old mic
In this step, you will gently unplug the mic cable (white connector) to remove the old microphone. Once this is done, you can now reverse the process and connect the new mic.
Step 4: Put everything back together
When putting the microphone assembly back together pay special attention to the tab markings. Replace the microphone assembly cover and secure with two screws. Finally, reconnect the cable assembly to the headset and tighten the screws.
Congratulations! That's it, you're done. Now test everything out then go fly.