Sunday, April 27, 2014

Small Error In Auxiliary Audio Wiring Discovered

After spending another couple of hours this morning searching for the missing bag containing the multimeter, test lead clips, solder, test jumpers and wiring hardware … the bag was finally located much to my relief.  Although, it was such a nice day today, not much time was spent in the shop … yet again.

That said, the other day while installing the wire harnesses, noticed what seems to be a small error in the prints for wiring the auxiliary audio connector. Today I took the time to investigate … it has been my experience that left channel audio is on the tip and right channel audio is on the ring of the typical 3.5 mm stereo plug used for MP3 players, headsets etc. If wired as per the plans, it appears that the left and right channels are switched at the ES00045 connector. Is that such a big deal? No … but it will make any audiophile cringe.
Aux music jack drawing and ES-000045 fuselage wiring harness connector.

When tracing the wires back they are indeed flip flopped on the drawing. The F397 is connected to the right music input and the F398 is connected to the left music input at the WH-00045 connector … pins 2 and 20 respectfully. I went further and traced the wiring diagram all the way back to the Garmin GTR 200 and all was good … right goes to right and left goes to left.
Using the multimeter to buzz out all the audio wires to the WH-00046 and WH-00045 wiring harnesses.

My suggestion to other builders is consider flip flopping the F397 and F398 wires at the ES00045 connector by connecting F398 (left music input) to pin 1 (tip) and F397 (right audio) to pin 2 (ring) of the ES00045 connector to achieve proper left and right stereo orientation.
Photo of the wiring diagram … zooming in one can see F397 is wired to right music input and F398 is wired to left music input of the WH-00046 harness.

All this got me concerned about the left and right audio for the headsets as well ... because the Garmin GTR 200 has a feature called 3D sound where active and standby radio channels are heard at the 11 and 1 o’clock positions and the co-pilot at 3 o’clock.  Happy to report all is well … according to the wiring diagram, tip (left audio) of the headset jack goes to the left headset audio on the GTR 200 and ring (right audio) goes to right headset audio. Of course, this presumes the wiring diagram is correct and can’t really test that at this time because the instrument kit has not been ordered yet.