LEMO adapter cable

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Rich
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LEMO adapter cable

Post by Rich »

As many are aware, the dual-plug headset jacks in most GMA340-equipped DA40s are designed to supply power to no-longer-available Sennheiser ANR headsets. This appears to make the feature totally worthless unless one goes to the considerable difficulty of installing LEMO sockets and tap that power line connected to the microphone jacks.

Not so fast, grasshopper.

I've determined it's feasible to fabricate a DA40 dual-plug adapter cable that supplies power to the LEMO plug from that existing dual-plug jacks.

Here's the overview:
The headset microphone plugs are physically identical to hand-held microphone plugs. The very tip section (of the three) is used for push-to-talk from such mikes. Headsets with the GMA340 neither need nor use this feature, yet standard dual-plug GA headset microphone plugs still have the three contact points and connect to the prong in the jack that is normally used for this function. It is this prong that has the DC power source connected to it in the DA40. I confirmed this today. So your everyday headset connector has 28 VDC sitting right on that tip piece of the mike plug.

Therefore a powered dual-plug <-> LEMO adapter cable is feasible. In fact dual-plug <-> LEMO adapter cables exist today, but do not claim the power-delivery function. It is likely they simply ignore this tip piece and don't bring the required third conductor from the mike plug to the required #1 LEMO pin. My mission now is to find out if there are any cables out there that (accidentally or otherwise) provide the necessary connection. Failing that I'll be hunting parts to fabricate one myself. This is useful to me as my BluLink-equipped stuff can be powered using A20 6-pin LEMO hardware.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Tim H
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Re: LEMO adapter cable

Post by Tim H »

You've got me thinking, I wonder if you could pull the power off an unused jack and use it for a USB port?
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Rich
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Re: LEMO adapter cable

Post by Rich »

I couldn't find a product that does this but was able to cannibalize a couple of things to construct a cable that works. I'm waiting on a part that I believe will result in a cleaner device. It will require some tweaking but should look better.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: LEMO adapter cable

Post by Rich »

So this dual-plug / LEMO adapter from Pilot-USA does not supply power. But the LEMO connector assembly is easily opened up to expose the wiring to the back of the 6-pin connector itself. This product does bring the microphone tip connector almost to the LEMO connector. The relevant (blue) wire is cut off about 1/2 inch short of the #1 pin. So the task is to bridge that gap with a short bit of wire or cut all of the wires and complete the full connection. But I need a better soldering iron first, as it needs precision work to pull off.
Pilot-USA LEMO Adapter.jpg
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: LEMO adapter cable

Post by Rich »

I tested my prototype today in the hangar with the Carbon A1/BluLink headset with the batteries removed from the control module. It works like a charm. ANR and bluetooth fully functional from ship's power alone :thumbsup:
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: LEMO adapter cable

Post by Rich »

I was looking at the most recent (rev eight) release of the AMM and it appears that Diamond is still supplying power for the no-longer-available Sennheiser headsets. Weird. I was thinking of encouraging Pilot-USA to produce, as a standard product, a variation on their PA-89/A20 that has that blue wire connected to pin 1.

Does anyone know if anyone other than Diamond that has done this?
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: LEMO adapter cable

Post by blsewardjr »

Rich- If I understand what you're doing correctly, this only works if you have headsets with LEMO connections. If you don't is there a cable that can convert a regular ANR headset connection to a LEMO headset? Does this work only with Bose A20s? Thanks. Bernie
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Re: LEMO adapter cable

Post by Rich »

blsewardjr wrote: Sat Dec 18, 2021 2:00 pm Rich- If I understand what you're doing correctly, this only works if you have headsets with LEMO connections. If you don't is there a cable that can convert a regular ANR headset connection to a LEMO headset? Does this work only with Bose A20s? Thanks. Bernie
To clarify, the approach I'm taking allows one to simply use the existing dual-plug setup in the DA40 for one's "normal" headset. There is no alteration to the plane itself. And it only works in planes configured for the long-defunct Sennheiser ANR headsets.

It is for anything that can use a A20 6-pin LEMO connector and make use of ship's power from pin 1. There are adapters that provide dual-plug to LEMO conversion but leave pin 1 unconnected. Among these is the Pilot-USA adapter that I am modifying. In my case it's because the newer BluLink devices and the Carbon A1 ANR control modules can use the LEMO pin 1 for power and bypass the AA's when doing so.

There are other manufacturers' headsets that have also adopted the 6-pin LEMO plug as an option - Lightspeed Zulu3, e.g.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: LEMO adapter cable

Post by blsewardjr »

So I found a Fixed Wing Headset to Panel Power Adapter which would allow my Zulu3 with dual regular connectos to connect to your modified LEMO connector. However, the adapter has the same issue as you found with your connector -- it does NOT power the headset, it only allows you to connect to a LEMO plug for audio. Therefore, unless it also could be modified as you have done AND the Zulu 3 would accept the power without batteries, I would need to purchase a new Zulu3 with LEMO plug rather than the regular dual plug.
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Rich
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Re: LEMO adapter cable

Post by Rich »

blsewardjr wrote: Sat Dec 18, 2021 3:28 pm So I found a Fixed Wing Headset to Panel Power Adapter which would allow my Zulu3 with dual regular connectos to connect to your modified LEMO connector. However, the adapter has the same issue as you found with your connector -- it does NOT power the headset, it only allows you to connect to a LEMO plug for audio. Therefore, unless it also could be modified as you have done AND the Zulu 3 would accept the power without batteries, I would need to purchase a new Zulu3 with LEMO plug rather than the regular dual plug.
Not surprising. The tip of the microphone plug was originally intended for a push-to-talk circuit. Modern audio panels and headsets don't use it, but Sennheiser co-opted it for ANR power. It's conceivable that your Zulu3 input wiring could be modified to accept the LEMO input, but that would be truly adventurous and might not work.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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