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  #1  
Old 09-15-2010, 09:27 PM
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Noah Noah is offline
 
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Default ANR Panel Powered LEMO Connector Wiring

I'm installing aircraft-powered LEMO connectors for ANR headsets. These have shielded cable pigtails with two conductors each, as well as three small black wires. Two of these are connected to the shields at the connector end, and the third is connected to pin 2.

I also have two shielded 3-wire audio cables from my audio panel pre-purchased harness. The LEMO jacks are about 8-10 ft away from the audio panel, and the "splices" between the 2-wire LEMO cables and the 3-wire audio panel cables will be in about the middle of that run.

Pg. 18 has a schematic:
http://www.bose.com/pdf/customer_ser..._headset_x.pdf

But there are a few unanswered questions:
1. Should the black wires connected to the LEMO shields be locally grounded? Although the online version doesn't say so, the paper copy I received from Bose says they should. This seems to contradict other things I have read.

2. Should I try to keep shielding around the wire splices I make between the two cable pairs? In other words, will having a few inches of exposed, non-shielded wires result in noise?

3. Should I solder the shields together at the splice or just solder the black wire to the shield of the three-wire cable from the audio panel?

Thanks for any help with this.
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  #2  
Old 06-08-2014, 12:44 PM
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AAflyer AAflyer is offline
 
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Default Still wondering?

Noah,
I just posted a similar set of questions. Have you solved your problem? What's the answer?
Thanks.
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  #3  
Old 06-08-2014, 03:38 PM
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Noah,

You would use the two black wires from the audio shields on your LEMO connector only if you were going to splice into existing conventional audio jacks. Here is the Bose schematic that illustrates how to do this:



Normally, shields are grounded only at the audio panel, so in your case where you are using just the LEMO connector, I would not utilize the two shield grounds at the LEMO connector. If I were incorporating conventional audio jacks, then I would follow the schematic above. The other ground (pin #2) is the power ground for your 12 volts in, so definitely ground this wire.

Also, you will have to wire a grounding circuit for your PTT switch. Normally, this would consist of a wire from the PTT pin in your audio panel, through your PTT button on your grip, and then to ground.

Hope this answers your questions.
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  #4  
Old 06-09-2014, 08:46 PM
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Wow! Since I asked these questions almost 4 years ago, I have no clue what I did

Hopefully Pat answered your questions.

Makes me wonder if the alternator whine I hear is related. Somewhere I have pencil and paper diagrams of what I did (I hope) that will eventually become real schematics (but probably not).
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All men dream, but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous menů for they may act their dream with open eyes, to make it possible. -T.E. Lawrence
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  #5  
Old 02-25-2018, 02:28 PM
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To add the Bose lemo connector to prewired aviation dual plugs in a flying RV, should the wires be connected to the existing jacks so the you have 2 wires on each lug, or should they just be spliced in to the existing wires close to the jacks?

~Marc

Quote:
Originally Posted by Pat Hatch View Post
Noah,

You would use the two black wires from the audio shields on your LEMO connector only if you were going to splice into existing conventional audio jacks. Here is the Bose schematic that illustrates how to do this:



Normally, shields are grounded only at the audio panel, so in your case where you are using just the LEMO connector, I would not utilize the two shield grounds at the LEMO connector. If I were incorporating conventional audio jacks, then I would follow the schematic above. The other ground (pin #2) is the power ground for your 12 volts in, so definitely ground this wire.

Also, you will have to wire a grounding circuit for your PTT switch. Normally, this would consist of a wire from the PTT pin in your audio panel, through your PTT button on your grip, and then to ground.

Hope this answers your questions.
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  #6  
Old 02-25-2018, 03:39 PM
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Quote:
Originally Posted by Plummit View Post
To add the Bose lemo connector to prewired aviation dual plugs in a flying RV, should the wires be connected to the existing jacks so the you have 2 wires on each lug, or should they just be spliced in to the existing wires close to the jacks?

~Marc
I updated my RV-6 to include LEMO jacks a little over a year ago. I added wires from the LEMO jack to the existing GA jacks. (soldered wire coming from LEMO to lug on the GA jacks) I then needed to run power and ground forward from the LEMO jacks to tie into my electrical system. I may have been able to use a local ground but have a single ground point for everything else in my airplane so keep the same for the new addition.
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  #7  
Old 03-02-2018, 07:05 AM
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Quote:
Originally Posted by RV6_flyer View Post
I updated my RV-6 to include LEMO jacks a little over a year ago. I add.ed wires from the LEMO jack to the existing GA jacks. (soldered wire coming from LEMO to lug on the GA jacks) I then needed to run power and ground forward from the LEMO jacks to tie into my electrical system. I may have been able to use a local ground but have a single ground point for everything else in my airplane so keep the same for the new addition.
Thanks Gary. The schematic that I down-loaded from Bose shows the ground wire (pin 2) going to the barrel of the phone plug. I thought the ground should go to the aircraft ground buss bar to avoid ground loops. I'll call Bose today and see what they say.

-Marc
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  #8  
Old 03-02-2018, 08:36 AM
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Quote:
Originally Posted by Plummit View Post
Thanks Gary. The schematic that I down-loaded from Bose shows the ground wire (pin 2) going to the barrel of the phone plug. I thought the ground should go to the aircraft ground buss bar to avoid ground loops. I'll call Bose today and see what they say.

-Marc
The barrel of the .250 jack, which pin 2 goes to, is grounded at the audio panel, along with the wire shielding. It is generally better to connect audio grounds together, then tie that into the main ground point.
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Last edited by Raymo : 03-02-2018 at 08:46 AM.
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  #9  
Old 03-02-2018, 09:41 AM
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Quote:
Originally Posted by RV6_flyer View Post
I updated my RV-6 to include LEMO jacks a little over a year ago. I added wires from the LEMO jack to the existing GA jacks. (soldered wire coming from LEMO to lug on the GA jacks) I then needed to run power and ground forward from the LEMO jacks to tie into my electrical system. I may have been able to use a local ground but have a single ground point for everything else in my airplane so keep the same for the new addition.
That's what I did - I already had my dual-plug connections built when I decided to jump ship and go with panel-power. I wanted to keep the dual-plug for possible future use (you just never know) so I added the Lemo but making the connections directly to the relevant points on the dual-plug. 200+ hours later it's still working great.
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  #10  
Old 03-02-2018, 09:45 AM
jliltd jliltd is offline
 
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We fought a bad audio problem in an Air Tractor with Bose A20 upgrade in the helmet and the LEMO receptacle. No standard headset jacks in parallel. No audio panel or intercom (single seat). Just LEMO receptacle wired directly to the single GTR 225 comm radio. We tried changing out transceivers, tried to set gains and all manner of troubleshooting with the fellow who installed the wiring. Naturally since the sparky did the wiring he approached the entire problem with the assumption his installation was right.

I noticed the referenced black shielding wire leads provided by Bose were connected to the comm radio Dsub backshell as is standard practice for shield drains. So I cut them free at the radio connector and all our troubles went away.

So my takeaway on this is that if you are not a tying a new LEMO assembly in to existing standard panel jacks per Bose's drawing assumption, leave those two black leads unconnected.

Jim
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Last edited by jliltd : 03-02-2018 at 09:48 AM.
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