Intercom Audio Input

The place to raise issues, ask questions, swap ideas and discuss anything related to aircraft engineering, maintenance and building.
NB Any opinions expressed in this forum are not necessarily those of LAA Engineering

Moderators: John Dean, Moderator

Post Reply
Towline
Posts: 2
Joined: Mon Feb 12, 2018 10:44 am

Intercom Audio Input

Post by Towline » Mon Feb 25, 2019 1:53 pm

Hi, I'm looking for some help with the 403MC intercom.

I'd quite like to get it set up to work with SkyDemon's audio alerts via my iPad.

I gather that I will need the following to enable audio input to the 403:
  • D-sub pin
    Shielded twisted pair wire
    3.5mm jack to put somewhere in the panel
    Pin insertion tool and crimp tool
I'm stuck on what type of pin, how I implement this into an existing intercom and any advice from those who have already done it!

Jon
Jon Salmon
042774
RV-6
Cotswolds

tnowak
Posts: 435
Joined: Wed Jan 02, 2008 12:00 pm

Re: Intercom Audio Input

Post by tnowak » Tue Feb 26, 2019 8:34 am

Jon,

I haven't done it before, but do you know if your current wiring and connector has the pin for the ext audio input?
D type connectors are very common and your connector may already have the pin ready for you to connect your wire to. Looking at the manual it looks like you simply solder a wire to pin 18?

Tony
Tony Nowak
008249

User avatar
John Dean
Moderator
Posts: 300
Joined: Wed Jan 02, 2008 12:00 pm
Location: Kent

Re: Intercom Audio Input

Post by John Dean » Tue Feb 26, 2019 6:18 pm

Jon,

As Tony says it's just, in theory, a matter of connecting pin 18 of the connector and an earth to your 3.5mm socket.

However, in practice, in can be a very difficult job. The D sub connector plugs in to the rear of the intercom and a lot depends on how easy it is to get to remembering that the many other wires will probably prevent you moving it to somewhere its easy to see it. The connector will have a casing which needs to be removed and you should then be able to see if it is of the type where the wires are soldered to the pins or one where the wire is crimped to a pin and then the pin inserted into the connector. You do not require an insertion tool for this but you would need a tool if you wanted to remove the pin.You do need a crimping tool which are not cheap. You also need to look at Pins 23,24 and 25 which control the muting of the input.

It may be that whoever originally installed the intercom included a wire to Pin 18 and didn't connect it but that's wishful thinking! Much depends on the installation on your aircraft as to whether it will be possible to do the alteration easily or if it would be just too much work. In the two installations of the 403MC intercom that I have done, I wouldn't have liked to fit another wire after having done the installation.

Easiest solution is an ANR headset with a suitable socket in the battery box. Plug one end of your wire in there and the other end in your ipad's audio socket and jobs done!

Towline
Posts: 2
Joined: Mon Feb 12, 2018 10:44 am

Re: Intercom Audio Input

Post by Towline » Wed Feb 27, 2019 10:25 am

Thanks both.

Luckly the intercom is in a position where I can remove it from the panel and rest it on the cockpit wall by standing at the leading edge of the wing. I'll check this weekend to see whether pin 18 has been wired.

I must confess I that hadn't even thought of plugging my iPad into my headset. :oops: :lol:
Jon Salmon
042774
RV-6
Cotswolds

PaulSS
Posts: 43
Joined: Wed Mar 15, 2017 7:04 am

Re: Intercom Audio Input

Post by PaulSS » Thu Feb 28, 2019 12:41 am

What sort of headset do you have, Jon?

If it has built-in Bluetooth then the simplest way is to pair your iPad with the headset and then you'll get the audio sans wires.

If your headset doesn't have Bluetooth but it has a 3.5mm aux input then you could buy a Bluetooth receiver, plug it into the aux input and still get the audio without wires all over the place.

Something like: https://www.ebay.com.au/itm/Wireless-Bl ... :rk:1:pf:0
Paul Simmonds-Short
042301

Post Reply