Paul 5r4

Paul 5r4

Well Known Member
I have the D 100 and the D 120. I've wired up per dynon's instructions with the variable resistor from radio shack. My problem is this. I have BARELY any tone in my headset when I press the audio test buttons on either dynon instrument. If the engine was running I wouldn't hear them at all. I've tried both pilot and co-pilot sides, played with any and all volumes etc. I've double checked the ground as well as the rest of the wiring and all looks ok.

I did find a post from Stein from 2009 that said dynon "audio out" alarms don't play well with the flightcom intercom. That's what I have. Is this still the case? His advice back then was to cut the wire and forget about having an audible alarm. I was sure hoping to have this feature. Any help is appreciated!
 
First check is to make sure you have the variable resistor wired up properly. There are three connections. The two outer connections should go to ground and to the audio source (the Dynon Audio Out pin). The center connection should go to the intercom.

Second check is to determine verify that output from the center connection of the variable resistor is going to pin 18 of the Flightcom. The aux input for the Flightcom is pin 18 and 19 for stereo input, but the manual specifies that mono input has to go to pin 18.

Final check is to verify that you are using the correct variable resistor. Dynon specifies a 10k ohm variable resistor. The resistor is not supplied by Dynon or by Flightcom, so there is a chance that you have the incorrect resistor installed.

Perhaps a check from a different source would be useful. Hook up a 3.5mm audio jack to Pins 18 and 19 on the Flightcom, and then plug in your iPod / cassette player / 8 track player to see how it sounds...

Good luck!
 
Scott....

Thanks for the quick response. I think I've done each thing you suggest. The variable resistor is wired correctly, (and it is the correct VR per the part number in the dynon manual), and the center post goes out to pin 18. I will double check that again though just to be absolutely sure. More data here is that everything else works fine with the "sound" system... comm radio loud and clear etc. If I plug in an MP 3 player to the aux input it plays great in the head sets too. My only anomaly is the sound from the audio alerts is just almost not there! Still scratching my head and again I appreciate any responses.

P.S. Has anyone else got theirs wired up with my same equipment and working ok?
 
If your issue is "too quiet" than you might as well remove the variable resistor completely for now. This only reduces volume since it's too loud in 90% of airplane installs. At least you can start here and remove one variable.

Actually, I'd start with just the D100 wired direct to the intercom, no resistors or parallel connections to other equipment. If that's too quiet, then you're kind of stuck.

Sorry I don't have much else to suggest. You can call Flightcom and ask them what the specs are on the input you are connecting to and maybe we can figure out what is up. The output from the D100 is supposed to look a lot like the output from a COM radio, so it should work.
 
The Dynon support guys are right...also note that my response was from some years ago when the Dynon was significantly different (and the HS34 didn't exist). Anyway, at the time the audio outputs from the Dynon were overbearing without a resistor, and sometimes it was hard to match it - so in those cases (and without an HS34) it was frankly just better to disconnect it because in my opinion the Flightcomm just didn't work well with it. This was a common problem in CT's for awhile and a few others with certain configurations of the Dynon and the Flightcomm. It also depends a quite a lot on which intercom version you are using, which input into the intercom you're using and how you have it wired/grounded, etc.

Sorry there isn't much better news...

Cheers,
Stein
 
UPDATE... problem found!

This morning I went to again trouble shoot the alarm problem. I did like dynon suggested and took the variable resistor out of the loop plugging the EMS directly into the aux input, (pin 18), of the flightcom. The problem was still there. I could still just barley hear a tone. I began playing with the wire where EMS and Flightcom came together and POW... tone! This is when I realized that this area was also a common point between the EFIS/EMS and the flightcom. Then I hooked the EMS back to the variable resistor along with the EFIS and jiggled the wire again and have tone to both instrutments. I had checked EVERYTHING... two or three times but unfortunately for me, I had not checked this single point. It was such a simple problem.... one of those I couldn't see the forest for the trees! Thanks guys!
 
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