Right Angle Mic Plug Adapter

[Tcheairs]

I'm attempting to fabricate a right angle mic plug adapter (Bose Aviation X headset with ANR) which plugs in overhead behind me on my tip up RV7A. (interferes with access to the baggage compartment)

I'm assuming this is a 3 wire connection for the .206 male mic jack from the Bose headset. I do have ANC in my Aviation X. I'll probably wire the Switchcraft S-206 to a female jack which will receive my mic plug from my headset.

Does anyone know whether or not I am correct in assuming a 3 wire connection is all that's required for a Bose mic connection..tip (mic) ring (mic audio out) and sleeve (common ground). And to go one step further, does anyone know the color codes in the Bose mic jack corresponding to these 3 connectors? I don't have a "donor" cord to "disect" to see the colors.

Here's a link to a schematic of the Switchcraft S-206 plug

 

[BobTurner]

The tip connection is conventionally used for a PTT switch (ground the tip to transmit). Ring is mike out, sleeve is ground. In my aircraft I didn’t even both wiring the PTT connection to the mike jack - I use PTT switches on the sticks. (If mine fails in flight I’d have to move my plugs to the other side, and use the copilot’s PTT button.)

 

[Tcheairs]

Rt Angle Mic connection

Well, I found a donor Bose mic cord and plug and opened her up. The male plug itself has not 3 but 4 contacts. I was not able to open it up to see where the wires were connected because it is protected by a heavy plastic shield which is glued to the connector. There are a number of wires inside the mic cord. Black, white, green, yellow and orange. It's hard to believe that they are ALL connected to the plug somehow.

Photos attached..guess I'm going to have to get some help from the Bose folks.

 

[Tcheairs]

RT ANGLE MIC

I have a PTT on my stick as well, but won't I need a 3rd connection on the mic plug to have my transmission fed back to my headset? Or does that come directly from the comm panel?

 

[BobTurner]

Wow, this is a non standard plug with two ring terminals! (Compare to figure in first post.) I have no idea what’s going on here.

 

[BobTurner]

I have a PTT on my stick as well, but won't I need a 3rd connection on the mic plug to have my transmission fed back to my headset? Or does that come directly from the comm panel?

Hearing yourself (called ‘side tone’) is generated within your transmitter and fed back thru the other audio connector (1/4” stereo plug).
My guess is that for manufacturing convenience they just used one cable for both the 6 pin plug or the separate .25” and .208” plugs. If you use an exacto knife and slice open that plastic shield you’ll probably see one wire connected to one of ring terminals, one to the barrel, and maybe one to the shield. Use an ohm meter to figure out what is what. The other wires will, I think ( guess), just be terminated in a shrink wrap insulation.

 

[Tcheairs]

Bob, I found the manual online for my Bose Aviation X headset. Here are the wiring schematics for the headset. I'm afraid it's all above my pay grade.

 

[BobTurner]

Okay, it’s about what I thought. Unfortunately they switched color codes from what they show (behind the panel wiring) compared to the to-the-plug wiring (which is not shown), as they show no green or yellow wires!)
Notice the mike plug only has two connections. The tip is just for PTT use and is not connected to the headset. You’ll have to plug the mike plug into its jack, and look and see which of those two ring terminals it uses. I think it’s the one farthest from the tip but not positive.

For optimum noise immunity most modern installations insulate the jacks from the airframe, and run a separate ground wire back to a single point ground on the audio panel/intercom. Many legacy installations do not. Same for ‘mike lo’. If your audio panel has a mike lo input, insulate the jack from the airframe and run back to the audio panel. If it does not have a mike lo input, just use a ground connection at the audio panel.

Which leaves me with my previous comment.
1. Look at the jack with the mike plug inserted, figure out which ring terminal it uses, use an ohmmeter to figure out which wire is connected (if you can’t see the connection scrape the insulation off a small spot on each wire to use with the ohmmeter).
2. Figure out the mike lo/ground wires attached to the barrel.

 

[Tcheairs]

Good idea, but I have no access to the mic female jack as it is installed in the overhead structural member which supports the rear window aft of the roll bar. Must have been installed (with wiring) when the RV7A was built. That's what's driving this project in the first place and the need to get these wires up along the roll bar and out of the way.

Thanks for your thoughtful input, Bob Guess i'm stuck with this inconvenient comm setup. But Could probably pay somebody a lot of money to install my jacks under the instrument panel. or near the armrests.

 

[BobTurner]

While a good, neat job would remove the old hardware and wiring, just abandoning it in place is not unreasonable. The cost of jacks and shielded wiring is pretty modest. Worst part is gaining access to the connector in the back of your audio panel.