Comm issue

[anthonydesmet]

Folks,

Took off today to drop airplane at Dugosh. 20 minutes from home base everything worked fine.  Got the switch from departure to center and stopped receiving on all comm jacks and two different headsets. When I transmit I could see the TX on the G430 and the G250 and I could see the RX when folks tried to reply. When I got back to home base people in the pattern could hear me transmitting in the blind but I couldn’t hear them with intercom in pilot isolate or intercom or speaker on both radios. We tried swapping comm control panel but no luck. Right now everything is ver faint we can hear with the motor not running 

[PeteMc]

So with two radios having the issue, it would suggest it's not the radios.  But it takes two seconds to make sure the connectors are seated correctly on the back of the radios and the Comm panel.  Were the radios removed recently?  There's a chance that some pins were bent and for some reason it just took a while for you to get a short on the speaker/headset side.   Does the Speaker have the same issue?  

And when you swapped the Comm panel, did you look at the connector.  Hard to see it really when connected to the tray, but you might see something.  But make sure that connector on the back does not have anything pulled loose, etc.

 

 

Edited February 20, 2024 by PeteMc

[anthonydesmet]

No radio work recently. Swapping audio panel had same issue and as you stated all seems secure behind the audio jacks.  Speaker works fine which is leading me to believe it’s the ICS/VOX box.  But I do get a green light on the ICS/VOX box so it has power.

[anthonydesmet]

UPDATE and still looking for advice.  I was able to get a second N.A.T ICS/Intercom box and swap but still same issue as above. After trying different audio panel boxes and this ICS box does anyone know where there is another spot behind the stack that all headphone jack’s eventually come together that might be causing no receive audio in all headphones on both radios? Again, speaker audio is fine.

[cbarry]

Could it be that vibration over time may caused have one of  comm jacks to  become loose or even possibly grounding out?    

[PT20J]

Maybe this will help.

AA80 InterVOX.pdf

[anthonydesmet]

20 minutes ago, cbarry said:

Could it be that vibration over time may caused have one of  comm jacks to  become loose or even possibly grounding out?    

That might be the issue. A few flights prior my pilot Jack was lose and comm was in and out until I hand tightened it.  Worked fine.  If that grounded the entire system how would one troubleshoot/resolve?

[cbarry]

9 hours ago, anthonydesmet said:

That might be the issue. A few flights prior my pilot Jack was lose and comm was in and out until I hand tightened it.  Worked fine.  If that grounded the entire system how would one troubleshoot/resolve?

I’m certainly not an audio system expert, but I can imagine if the insulator between the jack and the panel had failed or was missing then by tightening the jack it could have grounded out.  

[PT20J]

I have had this happen when the headset jack was not completely pushed in. Some of the jacks on my plane are pretty tight and with some headsets the jack feels seated but it's not and if I press hard in moves slightly and seats fully.

Another test of the ICS is to turn it's power off. This should fail-safe connect the pilot's headset directly to com 1.

Does your airplane have a set of emergency jacks on the panel and if so have you tried them? The audio output from the audio panel to the ICS runs through that jack.

If it's not the headset (you tried two), it's not the jacks, it's not the radios (they both indicate TX and RX and the speaker works), it's not the audio panel (you swapped that) and it's not ICS (you swapped that, also), then the only common point is the wire between the audio panel and the ICS. The audio panel is fortunately at the top of the radio stack so it is pretty easy to access with the glare shield removed and the ICS is probably also easy to access.

[KSMooniac]

A while back the fresh air duct on the right side under the panel migrated enough to contact the headset jack installed under the panel at the right sidewall.  After enough vibration, the duct material was breeched and the metal wire wrap was able to short the jack.  That was an aggravating nuisance until I found it by accident.

[anthonydesmet]

16 hours ago, PT20J said:

I have had this happen when the headset jack was not completely pushed in. Some of the jacks on my plane are pretty tight and with some headsets the jack feels seated but it's not and if I press hard in moves slightly and seats fully.

Another test of the ICS is to turn it's power off. This should fail-safe connect the pilot's headset directly to com 1.

Does your airplane have a set of emergency jacks on the panel and if so have you tried them? The audio output from the audio panel to the ICS runs through that jack.

If it's not the headset (you tried two), it's not the jacks, it's not the radios (they both indicate TX and RX and the speaker works), it's not the audio panel (you swapped that) and it's not ICS (you swapped that, also), then the only common point is the wire between the audio panel and the ICS. The audio panel is fortunately at the top of the radio stack so it is pretty easy to access with the glare shield removed and the ICS is probably also easy to access.

Thank Skip. Yes, I failed to mention- when I plug into my emergency jack it’s completely dead. I can’t hear the PTT like when I’m in the normal Jack. I get same result when I’m in the normal jack and I select pilot isolate on the ICS box.

 

Sitting here and since I was by myself I can’t remember if the ICS audio or XM music comes through. I guess that would one more step to isolate the jack or not.

[PT20J]

4 hours ago, anthonydesmet said:

Thank Skip. Yes, I failed to mention- when I plug into my emergency jack it’s completely dead. I can’t hear the PTT like when I’m in the normal Jack. I get same result when I’m in the normal jack and I select pilot isolate on the ICS box.

 

Sitting here and since I was by myself I can’t remember if the ICS audio or XM music comes through. I guess that would one more step to isolate the jack or not.

I would check the connections at the emergency jack. a short or open there would take out all the phone jacks because it is in the line between the ICS and the audio panel.

[LANCECASPER]

On 2/29/2024 at 6:28 AM, anthonydesmet said:

Thank Skip. Yes, I failed to mention- when I plug into my emergency jack it’s completely dead. I can’t hear the PTT like when I’m in the normal Jack. I get same result when I’m in the normal jack and I select pilot isolate on the ICS box.

 

Sitting here and since I was by myself I can’t remember if the ICS audio or XM music comes through. I guess that would one more step to isolate the jack or not.

I don't think you would hear the yoke PTT on the emergency jack. That's where the handheld mic plugged in. The push to talk was on the handheld mic.

[anthonydesmet]

Spent all day out there,  no luck. Wires appeared to be in tact.  Disconnected jacks from holder and checked washers and reinstalled.  I found three wires behind the audio panel (white with black stripe) that had a lose solder to the brass bar which I guess is a ground.  I tried to resolder but couldn’t get good contact. I did wrap them tight around that brass bar but no change.  Also speaker was still working entire time but when I went to leave, I have no speaker now and pilot PTT is out

[EricJ]

6 minutes ago, anthonydesmet said:

Spent all day out there,  no luck. Wires appeared to be in tact.  Disconnected jacks from holder and checked washers and reinstalled.  I found three wires behind the audio panel (white with black stripe) that had a lose solder to the brass bar which I guess is a ground.  I tried to resolder but couldn’t get good contact. I did wrap them tight around that brass bar but no change.  Also speaker was still working entire time but when I went to leave, I have no speaker now and pilot PTT is out

It sounds like maybe a connector is coming unseated somewhere, perhaps at the audio panel?   You might make sure that all the connectors at the audio panel and/or intercom are fully seated if you haven't already.

[anthonydesmet]

Does anyone know how many wires should be coming out of the pilot phone jack and the emergency jack?

[PT20J]

Check the schematics in the manual I posted above. With an AA80 InterVOX intercom (which is what I assume you have) each of the four primary phone jacks goes directly to the ICS, so there should be a shielded twisted pair to each jack: one wire connected to the tip and one to the sleeve. 

I agree with Eric that it sounds like a connector problem now that more things are failing. If you have a KMA 24 audio panel the three lugs on a strip at the rear of the tray on the upper left side (facing forward) are indeed grounds and the wires should be resoldered. Probably a dumb question, but are you making sure to turn the front panel screw on the audio panel all the way in so that the panel makes good contact with the connector?

Again, if it is a KMA24, the rear connector on the tray mounts with two screws from the front. I would check that the ears on the connector where the screws go through are not broken allowing the connector to be pushed out of position when the audio panel is screwed in. King used PCB edge connectors for the Silver Crown avionics and I have found that over time the pins on the tray connector sometimes don't make good contact. With the audio panel out you can access the connector through the opening in the top of the tray and use a small flat blade screwdriver inserted between the plastic body and each pin to gently push it toward the center of the connector so that it makes better contact when the panel is screwed in. I've had to do that with several different King radios.

[0TreeLemur]

51 minutes ago, PT20J said:

King used PCB edge connectors for the Silver Crown avionics and I have found that over time the pins on the tray connector sometimes don't make good contact

The KC-192 autopilot computer in my J has an intermittent connection.   Reseating the computer can cause it to start working again.  Would this adjustment work with those pins or should I get the pins replaced?

Thanks,

Fred

[PeteMc]

In my earlier post it doesn't look like I said to check for recessed pins in the connector.  It shouldn't happen if the connector was created with the right pins and done correctly, but it can happen and it easily can happen if the wrong pins were used.  And it may be a subtle difference, but if any of the pins are recessed/pushed back into the connector, you may be getting a bad connection or no connection at all. 

 

[PT20J]

1 hour ago, 0TreeLemur said:

The KC-192 autopilot computer in my J has an intermittent connection.   Reseating the computer can cause it to start working again.  Would this adjustment work with those pins or should I get the pins replaced?

Thanks,

Fred

I had to do that on my KC 192. The avionics tech that fixed an intermittent problem with between my GI 106 and KX 165 taught me that. 

[anthonydesmet]

Update: spent all day yesterday and verified audio panel has a good seat and the two black screws Skip mentioned are secure. Resoldered the three lose ground wires and also touched and verified each pin receptor in the ICS box connection and still nothing.  Got the speaker and pilot PTT to work though.  I also looked at each wire coming out of phone jacks and verified they travel and connect into individual sleeves that all look in tact.  Also took the shrink wraps off at each connection to verify all still secure.

i think my next step is to get plane to Dugosh for annual next Sunday VFR on speaker and hand held and let Gulf Avionics troubleshoot and/or start rewiring new audio panel and comm jacks in.

PIREP on Gulf Avionics at Kerrvile?

[affricate]

Happening to me right now, 

I can still use my speakers, PTT hand mic and plug my headphones into the emergency headphone jack. 

Got an appointment to replace the old NAT intercom and King KMA 24 out with something modern. 

Does anyone have any recommendations for a audio panel that allows one to adjust specific frequencies, like push up 4K HZ, etc?

(too many drums, rock and roll, guns, and cockpits !!!! )

[LANCECASPER]

12 hours ago, affricate said:

Happening to me right now, 

I can still use my speakers, PTT hand mic and plug my headphones into the emergency headphone jack. 

Got an appointment to replace the old NAT intercom and King KMA 24 out with something modern. 

Does anyone have any recommendations for a audio panel that allows one to adjust specific frequencies, like push up 4K HZ, etc?

(too many drums, rock and roll, guns, and cockpits !!!! )

You might make sure it's the audio panel that's bad by seeing if they have another KMA24 to slide in (or any PS Engineering 7000 series) and see if that clears it up. It might just be the internal amp that's bad. Or it could be the jack that's bad. If you haven't done so try the headset on the co-pilot's or a back seat jack.

As you know, the audio panel connects to everything in the panel and is very labor intensive. If that's all you're ever planning on doing, then go for it. But if you're planning on other panel work I would try to include the audio panel at that time. If a compatible used audio panel clears it up, then it might make sense to kick the can down the road until you do what you really want to do.

[affricate]

AA80 InterVOX.pdf

9 hours ago, LANCECASPER said:

You might make sure it's the audio panel that's bad by seeing if they have another KMA24 to slide in (or any PS Engineering 7000 series) and see if that clears it up. It might just be the internal amp that's bad. Or it could be the jack that's bad. If you haven't done so try the headset on the co-pilot's or a back seat jack.

As you know, the audio panel connects to everything in the panel and is very labor intensive. If that's all you're ever planning on doing, then go for it. But if you're planning on other panel work I would try to include the audio panel at that time. If a compatible used audio panel clears it up, then it might make sense to kick the can down the road until you do what you really want to do.

Thanks, going to have it all checked out next week. The avionics shop believes it's the old NAT intercom unit, and those aren't made any longer. 

[LANCECASPER]

1 hour ago, affricate said:

AA80 InterVOX.pdf 799.48 kB · 1 download

Thanks, going to have it all checked out next week. The avionics shop believes it's the old NAT intercom unit, and those aren't made any longer. 

True, but there are a bunch of them on eBay, that would at least rule out the wiring.