Audio Help Needed

[D&M Dan]

Ray,
I am not in a hanger, yet. However I hope to move the plane to the airport after I resolve this issue. I have had the plane outside, no change. Not a static issue, more of a muffled very faint audio. All most unhearable.

[Mich48041]

Dan,
Confirm using Van's schematic for SkyView prior to 8-25-2011.
I do not understand where on the schematic you see "GR/Wh to pin 13".
Do you hear the stall vane tone warning very faintly too?
Does it make any difference if the Flightcom 403 is switched to isolate?

[D&M Dan]

Joe,
Yes using Skyview electrical system shipped prior to 08/25/2011. I am looking at the headphone / microphone jack section of the drawing. It shows Pilot headphone blu-10, wh-9, Pilot mic Grn-13, orn-2. Co-pilot headphone jack, blu-12, wh-11, Copilot mic grn-13, orn-3.
These are the wires I am trying to pin out but not sure which connector I should be checking.
My wings are at the airport, so I cannot try the stall warner.
When the flight com is switched to isolate I get a loud tone in the headsets.

[Mich48041]

Dan,
OK, I see what you are talking about now. The numbers and colors are on the jacks themselves on Van's prior schematic. The headset portion of that schematic leaves a lot to the imagination. Download Van's Skyview AFTER 8-25-2011 and use that for the headsets.
The headphone and mic wires should be connected to the "OPTIONS" D-Sub on the AV-50000A, pins 24, 25, 26, 27, 28, 29, 37.
That loud tone in the headsets when switched to "ISO" makes me think that the problem is in the intercom or its wiring. Double check those wires.
There have been rare cases of harnesses having wires accidentally interchanged or on the wrong pins.

[D&M Dan]

Today I checked the intercom harness and all wires pin out correctly. With all phone jacks removed from the floor and outside the plane I tried grounding the Headphone jack to the ground on the mic jack. Resulting in a loud tone, even with the avionics switched off.
I also pinned out the jack wires to the option harness as Joe suggested and they are correct.
The intercom from pilot to copilot is also very faint and almost inaudible.
Not sure what to try next.

[BobTurner]

It's very hard to trouble shoot remotely, but here are a few things to try:
Re-install all jacks.
Look at every jack from behind as you insert a plug. Make sure the little fingers that make contact don't move outboard enough to contact anything (like a sidewall).
With harness attached but power off, put an ohmeter on the ground side of each jack, measure resistance to a good ground. It should be zero.
Disconnect the harness from the intercom. With no headsets plugged in, put an ohmmeter on the harness pin for each mike input and each headphone output, measure resistance to ground. They should all be infinite.

BTW, the mike jacks are wired to the 'ring' terminal, not the 'tip', right?

[D&M Dan]

Bob,
The mike jack uses the ring and sleeve terminal as per Van's drawing. I have no connection to the tip terminal.
Mike,
I have the jacks outside the aircraft so they cannot ground to the airframe. What is the best way to check ground back to the AV5000? The ring terminal has the correct blue wire called out per Van's diagram.
Not sure what infinite resistance is. I unplugged the harness and checked resistance from the headphone and mic output pins against airframe ground and I do get a reading.

[Mich48041]

Dan,
Does the volume change at all when the intercom volume control is turned?
You said that the radio transmits loud and clear. The mic audio is getting to the intercom, but it seems that the intercom is not amplifying the mic audio enough before sending it to the headsets. It is possible that the intercom volume potentiometer is defective.
On page 10 of the Flightcom 403 manual is Figure 13, a By-Pass Plug Wiring Diagram. I suggest that you make that D-Sub jumper and install it in place of the intercom. Of course the intercom between the pilot and copilot and other audio will no longer work. But you should be able to transmit and receive the radio. If then you can hear the radio OK, the problem is definitely within the intercom. Call Flightcom to discuss the problem.

[BobTurner]

Originally Posted by D&M Dan

Bob,

Not sure what infinite resistance is. I unplugged the harness and checked resistance from the headphone and mic output pins against airframe ground and I do get a reading.

"Infinite" means well over 100K (100,000) ohms. What are you reading (no mike or headphone plugged in)?
Mike INPUT pins.

[D&M Dan]

Sorry for not getting back right away. I have finally been able to spend time trying to sort through the wiring. Here is what I have done.

Went to Staples and had then print me a large copy of the wiring schematic so as I am more easily able to trace each wire.

Pinned out each lead for the Garmin SL40, Flightcom 403 and wiring through the AV5000. I can find no shorted or mixed wires as per Van's drawing.

Played with the potentiomenter for Com1. Had no effect.

Bypassed the Flightcom 403 with no change.

Reinstalled the headphone jack without the insulation washer. When turning on the master switch I immediately get a loud side tone, even without turning on the avionics switch. With the avionics switch on the volumn is much louder and controllable with Flightcom Volumn Switch now, but with the sidetone. Possibly a grounding issue somewhere? The ground wires I traced seem to be as Van's drawing depicts.

Also I do not know if this is related, but when scrolling through the Skyview setup I see 5 serial ports. Do these need to be setup?
#1 None Serial in Function None Navigation Source Display (Not Set)
#2 Dynon SV-ADSB-470 Serial in Function ADSB Navigation Source Display (Not Set)
#3 Dynon SV-XPNDR-261Serial in Function Transponder Navigation Source Display (Not Set)
#4 Garmin / Apollo SL40 Serial in Funtion None
#5 Dynon SV-GPS-2020 Serial in Function Pos 1 Nav Source Display *(Not Set)
Thanks for Helping, I appreciate the advice.