Here i show you how to add Mute Button to you Auna Mic 900. Auna is using the CM6327A USB audio Interface chip which has a integrated mute function which they decided not to connect so we need to do this by our self.
Optionaly you can connect the LED of you auna to the LED3 Pin. If you do so the LED will later indecate that the Mic is muted.
For the mod you need the following:
- 1x 1k Resistor
- 1x small Button (not to thick oatherwise it will be tricky to get the case back over)
- some thinn Wire
- a soldering iron with a very pointy and small tip
- some experience with smd soldering
If you want some more Information about the chip you can find the datasheet here.
Step 1: Teardown
First you need to Tear down the Mic until you can acces the chip. The PCB with no traces is just shilding and isnt connectet to anyithing and sofore can just be unscrewd.
For the next Step you may now prepare some realy thin wire. I used just one strand of copper out of a stranded copper wire.
Step 2: Soldering
This is the most triky part of the whole Project.
I pre tinned the copper strands and put sume flux on the pins of the chip. Then i alignd the wire with some tweezers and then quickly tacked them down with my iron at 300°C.
Remember soldering the wire for the LED is optional.
Step 3: Add the 1k Resistor and the Button
For this step i solderd the 1k resistor to my copper strand. Aferwards i secured everything with hotglue making shure the bare copper wire dosent short anything. Then i solderd the wire to the other side of the resistor and also secured it with hotglue. Also you can solder the Button now but leave enough slack in the Wire so you can fit the case with the button back on.
Step 4: Mount the Button and Reasamble the Mic
The other wire coming from the button needs to be connected to ground. For that you coud solder it to any groundpoint on the PCB but i just sripped the wire and wound it around a screw when reasambling it. Wich Connects the butoon to case ground.
For mounting the button i just drilled a small hole and secured it with hotglue.
Now you can reasamble the mic!
But make sure to atatch the mic clamp before closing it up, because you wont be able to slide it over the button without damaging it.
Step 5: LED Mod (optional)
For the LED mod you need to cut a track with a stanly knive as sown in the picture. This is the track suppling the LED with 5v. After that connect the mic and verify the LED isn't lighting anymore. Now you can solder the led wire to the free Pad as shown in the picture.
Optionaly you now coud switch the LED to a red one. Also the LED won't light to bright now because the chip only outouts 3.3V and on the negative side of the LED is a 450 Ohm Resister connected. To get around that i woud just cut the negativ wire of the led and add a lower value resistor and connect it directly to gound.