LEMO Connector to GMA - discrepancy

[supik]

Everyone seems to wire (or splice) the black (GND) wire from the LEMO (BOSE) connector to the AUDIO Lo (RETURN) Pin in the GMA.

I'm utilizing the LEMO only, I don't have the standard GA connectors. My connector incl. the wire bundle comes from David Clark.

Garmin GMA240/245 Install manual suggests to connect the black GND wire to the Backshield.

I have mine connected directly to the aircraft GND according with the David Clark LEMO diagram and I'm picking up some noise, incl. strobes.

So what's the best solution? Put the LEMO (GND) on the backshield (which doesn't indicate to me there would be much difference from my current wiring) or connect it directly to the AUDIO Lo (RETURN) Pin?

Attached is a screenshot from the GMA245 install manual.

Thanks,

 

[supik]

3 more diagrams

3 more pictures, one with the suggested DAVID CLARK wiring and the second is from Steinair I think -I might be wrong and the 3rd is from Diamond Aircraft.

 

[PilotjohnS]

Me think

I think the ground for the ANR circuitry should be tied to the headset ground since the plane power is used for the ANR circuitry and Bluetooth stuff. And theses headset ground should be a s close to the audio component as possible to minimize pickup from other stray grounds

I am going through this now.

I had a lots of bad comm stuff happening after paint, but as soon as I sanded the paint away from the antenna mounting screws, my comms have never been better.

Grounds for audio are really important since the audio signals are soo low power.

 

[N890GF]

I recently installed LEMO Plugs for my Dynon Intercom setup, and I tied the main ground to the grounding point at the intercom. I am going to update to a GMA 245 in the future when I add a second radio, so I began working on a wiring diagram. The top of the diagram shows the LEMO plugs and how they tie into the GMA. I will be grounding the LEMO plugs to the shield ground of the backshells of the GMA.

On the Dynon Intercom I tied the shield ground and the main ground to the same point at the intercom. I haven't flown yet, but all ground tests have passed with flying colors.

 

[g3xpert]

LEMO Wiring

Good Morning,

For some additional commentary on our wiring suggestions specific to the GMA 245(R) audio panel, please see this post.

Thanks,

Justin

 

[supik]

Thank you!