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  #1  
Old 04-19-2017, 09:19 AM
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DonFromTX DonFromTX is online now
 
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Default Audio Problems (was headset confusion thread)

I have a Dynon touch installed in an RV12, using the original D180 wiring with the Vans conversion harness to Skyview.
The only sound I get in the headset is the stall warning, and it seems weak. Audio tests produce nothing from the Skyview nor SL30 nav/com except a very faint "air rushing" sound. In the test setup menu, I THINK I could faintly hear two words repeated, but too weak to positively ID. I have numerous headsets, they all act the same, plugged into pilot or co pilot jacks.
Has anyone had a similar experience? My next action will be to check the connections between the headset wires and the conversion harness again.
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  #2  
Old 04-20-2017, 07:32 PM
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Well I checked all the wires from headset plugs to the 5000 box today, all were where they should be. One thing did pop up however, but I think it should make no difference. The two shielded wires called WH-RZ-942 (WHT) and WH-RZ-943 (WHT) (circled in blue in the attached photo) [IMG][/IMG]were not furnished in my wiring kit. It appeared they were only extension cords, so I just added some wires, but noticed I had not shielded them with a cover. Don't think that would cause my problem.
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  #3  
Old 04-20-2017, 08:19 PM
John-G John-G is offline
 
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Don .... Audio grounding (and shielding) can be a funny thing, especially if you are striving for low noise.

By not using a shielded audio cable for your patch, you have rendered all the wiring aft of your patch as un-shieilded. This is because the shield on the audio cable is typically only grounded at one end of the cable usually at the connector end (AV-50000A end). I would suggest continuing the shield ground beyond the patch. DO NOT just ground the shields to the air frame.

If the actual patch is very short .... you could just tie the two shields together around the patch using a small length of wire. If the patch is long, I would just pull out the wiring and replace it with shielded audio cable.

This is likely not going to solve your overall audio issue, but could help eliminate some background noise later down the road.

Did you also buzz out the other audio wires as well?
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Last edited by John-G : 04-21-2017 at 07:34 AM.
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  #4  
Old 04-21-2017, 07:28 AM
Mich48041 Mich48041 is offline
 
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Don,
The headset jacks need to be grounded in order to work. The best way to accomplish that is to run a dedicated ground wire between the jacks and the AV-50000A. And mount the jacks to the airframe with insulating washers. If there is no dedicated ground wire, then the jacks can be grounded by mounting to the airframe without insulating washers, at the risk of possibly picking up noise. Bottom line, no ground equals no sound.
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Old 04-21-2017, 08:33 AM
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Maybe we are getting somewhere now Joe, I have my headset jacks installed with isolating washers! However 31B-17 clearly shows and requires them!
I also notice that changes have been made, in that there is now a connector near the jacks that was not there when I installed my headset jacks. Is it possible that the grounding happens there? Furnished with my kit so long ago were just the wires RZ194 and RZ195 which were attached directly to the headset jacks.

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Don,
The headset jacks need to be grounded in order to work. The best way to accomplish that is to run a dedicated ground wire between the jacks and the AV-50000A. And mount the jacks to the airframe with insulating washers. If there is no dedicated ground wire, then the jacks can be grounded by mounting to the airframe without insulating washers, at the risk of possibly picking up noise. Bottom line, no ground equals no sound.
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  #6  
Old 04-21-2017, 09:14 AM
Mich48041 Mich48041 is offline
 
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Don,
Since your headset jacks have isolating washers, I will assume that the shield is connected to the jack barrel solder lug. If so, then the instrument panel end of the shield needs to be connected to the AV-50000A ground, OPTIONS D-Sub pin 37.
The barrels of the headset jacks need to be grounded somehow. Either use the shield (best) or a separate wire or remove the isolating washers (not recommended).
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Old 04-21-2017, 10:51 AM
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The instrument panel end of the shields are in fact connected to pin 37 of the options plug. I guess it is pull the wings again and see what is going on down there. Wait a minute, I can just ground the jack housings to ground inside the aircraft to see if that is the problem, right?

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Don,
Since your headset jacks have isolating washers, I will assume that the shield is connected to the jack barrel solder lug. If so, then the instrument panel end of the shield needs to be connected to the AV-50000A ground, OPTIONS D-Sub pin 37.
The barrels of the headset jacks need to be grounded somehow. Either use the shield (best) or a separate wire or remove the isolating washers (not recommended).
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  #8  
Old 04-21-2017, 11:44 AM
Mich48041 Mich48041 is offline
 
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Yes, you can do that. A cheap set of earbuds can be used for troubleshooting audio. Connect one wire to ground and probe audio connections with the other wire.
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  #9  
Old 04-21-2017, 08:17 PM
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[IMG][/IMG]That was it, thanks Joe!
I only had a minute, but turned on the skyview audio test,
and shorted out the jack to the airframe - and Heard "Dynon Skyview"
sweetly over and over! The problem was originally that jack was grounded to the airframe, see attached photo. Later it was said on the forum I think,
that you had to isolate both of them, and I did.
That apparently made an open circuit.
So I get to pull the wings again and fix that, however the jacks are currently furnished as a module. Do you know of any location where the wiring of that module viewable? I would like to make sure I upgrade to the latest wiring when I fix it. Do BOTH jacks need grounded? I assume the ground lug is easy to spot on them.

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Originally Posted by Mich48041 View Post
Yes, you can do that. A cheap set of earbuds can be used for troubleshooting audio. Connect one wire to ground and probe audio connections with the other wire.
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Last edited by DonFromTX : 04-21-2017 at 08:20 PM.
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  #10  
Old 04-22-2017, 07:05 AM
John-G John-G is offline
 
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Don,

Sounds like for sure your issue is with the grounding ... I'm thinking your patch is not continuing the shield continuity to the headset jacks and you have lost the ground for the headsets ....

OR, you may have been caught unknowingly in a little gotcha ... if the old method of wiring the headset jacks only relied on the ground coming from mounting the jack onto the seat pan and did not run the audio cable's shield to the headset jack's body ... that is your main issue now that you have added the isolation washers.

To answer your question .... Yes, both the headset jacks for pilot and co-pilot need to be grounded to the audio cable's shield. Need to look at the print but I believe the body of mic jack uses a different wiring and does not get attached to the shield.

When the isolation washers are used to mount the headset jacks (and it is a good idea to use them to keep noise levels as low as possible) it is imperative that the audio cable's shield is wired to the body (barrel) of the headset jacks because the audio cable's shield provides the "isolated" ground for the jacks. At the headset jack end of the wiring, if the audio cable's shield does not connect to the body of the jacks, you will want to connect the cable's shield to the body of the pilot and co-pilot headset jacks.

Going back to my original suggestion, if you run a wire connecting the shields for the two cables you made the patch between, I think you will find all is well (however, this assumes that the audio cable's shielding is attached to the body (barrel) of the headset jacks). Here again, if that patch is more than a few inches, I would suggest making the patch with shielded cable or run a new cable entirely.

As an example for the wiring, download the electrical schematic for say, the Knobs panel, which is a later version of the wiring showing the connector and audio headset jack "module" .... you can see on the schematic how the audio cable's shield is wired to the body of the jacks (this is a green line on the drawing if I recall correctly)... thus supplying the grounding for the jacks.
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Last edited by John-G : 04-22-2017 at 09:05 AM.
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