John H

I broke down and put a Roadtop Carplay unit in my 2014 W212. The new unit plays through the AUX connector. There is now a slight buzz at high volume that wasn't there before when using Bluetooth direct to my factory 4.7 sound system. (FYI Roadtop uses bluetooh to the unit but outputs via AUX.) The manual suggests if buzzing is noticed that two ground wires be connected to each other. I did this as there was major buzzing which is now light buzzing.

I tried a $10 ground isolator in the AUX cable and while it reduced the buzz is destroyed the sound. Any suggestions?

nateo83

did you try connecting the grounds together? On the comand there is an aux shield and an aux ground wire, in addition to left and right channel. I’m buying some rf shield tape and i’m going to tape up the Left and Right aux leads individually and also will try a dummy plug. I am also going to undo the harness and tape the aux in wires between the android device and the COMAND to reduce buzzing along the length. And, I also bought a random noise isolator on amazon.

i followed the instructions on this forum to enable the aux in without connecting to the centre console, so I may just also trim back the rca leads to further reduce noise input.

and finally, i believe there is a way to connect the android screen to the stock bluetooth which should completely remove any noise potential…

that’s my plan of attack…

cheers

CaliBenzDriver

your plan sounds right to cure this noise. Make sure Android system and output are a single point (no loop) with Comand.


> Interface...:
Do you know if the Aux Input is directly into Comand unit or through the Media Interface module ?
If that's the case, I can take a look at Interface module for ways of improving noisy design with decoupling caps etc...


> Noise source...:
Is the Aux Input noisy or is Android Output noisy?
Try using a battery powered source for testing.
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nateo83

interface is direct into it, although I have the AMI so that just means the one leg out to the console is loose and the actual rca inputs are also loose.

for noise source - it’s the car alternator. When I turn off the car and it’s just power from the battery the noise stops. So one thing I may have to do is put a noise filter on the power lead to the android unit….. i’m unsure if I need a 15A or 30A for it. My guess is 30A or less.

nateo83

and now weirdly it’s not the alternator. When i pulled out the unit and put RF blocking tape over the LTE and GPS antenna inputs, and the RCA input legs it stopped. Also, I just disconnected the RCA input legs as I enabled the internal aux connection - to reduce another area of potential interference.

i also put RF blocking tape on any loose wire lead and then bundled it together.

problem (fingers crossed) seems gone playing audio now. Will try with phone calls and MS Teams calls.