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RV-12 audio feedback problem

Hi Joe,

I shall confirm jacks are isolated and determine which Dsub pins 2 and 20 are located....Thank you for the clues..Doug
 
The coax shield and wires connected to the sleeves of the audio jacks are grounded to Van's control board only, not to the airframe. According to Van's SkyView Prior schematic, the coax shield and Wht/Grn wires are connected to Options pin 37 (Gnd); and the Wht/Blk wires are connected to Autopilot pin 12 (Gnd). Microphone jacks and music input jacks are the most vulnerable to noise because those inputs get amplified. Ground them at the control board only, not to the airframe.

Thanks Joe!
Scott
 
Ferrite Modules

Hi Joe,

I shall confirm jacks are isolated and determine which Dsub pins 2 and 20 are located....Thank you for the clues..Doug

Joe, it will be a few days to follow-up on suggestions. In the meanwhile, Question: What is your opinion about installing ferrite modules and where?

Doug
 
Doug, ferrite beads and cylinders will not eliminate audio frequency noises.
Here is a troubleshooting test:
Unplug all headsets and music inputs.
Unplug the FUSELAGE and OPTIONS connectors from the AV-50000A control module.
Now check the continuity between the airframe and the headset and music jacks.
There should be none.
 
Pins 18/19 IC Dsub vs. 2/20 on Fuselage Dsub

Joe,
While waiting to get out to the field hopefully this weekend....the audio noise unknown's have me wandering around the Forums trying to refine my clues. Question: What is different between pulling IC Dsub pins (18/19) and Control Module Fuselage Dsub pins (2/20)?
 
Intercom pins 18 and 19 have audio output to the intercom from more than one source, i.e., EFIS & music & whatever.

Fuselage D-Sub pins 2 & 20 only carry audio input from the music jack.
 
Intercom pins 18 and 19 have audio output to the intercom from more than one source, i.e., EFIS & music & whatever.

Fuselage D-Sub pins 2 & 20 only carry audio input from the music jack.

Joe, pulled 2 and 20 same noise and now no IC input. I guess adjust efis pots? Or disconnect IC pins 18 and 19 next???
Noise is a whine/angry hi pitch bee sound. It increases with rpm can't hear it with passive headphones as easily but engine noise is loud. Can hear the blinking strobes and pulsing landing lights all caught up in the whine. I didn't do the headphone jack conntinuity check yet????any ideas? I'm stumped. I did get a good look at all the wiring. There is no 496 loop you mentioned it whines with the gps Off as well.
 
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Since you mentioned needle, I assume that you have an analog meter, which is fine. It needs to be be set to measure resistance. The meter might have "R" for resistance, or the ohm symbol Ω. Test the meter to be sure it is working. The needle should swing from one side to the other when the meter leads are shorted together. Connect one of the meter leads to bare airframe metal and the other lead to each jack, one at a time. The needle should not move when the jacks are touched.
The headsets and D-Sub connectors "FUSELAGE" and "OPTIONS" should be unplugged during this test.
 
Since you mentioned needle, I assume that you have an analog meter, which is fine. It needs to be be set to measure resistance. The meter might have "R" for resistance, or the ohm symbol Ω. Test the meter to be sure it is working. The needle should swing from one side to the other when the meter leads are shorted together. Connect one of the meter leads to bare airframe metal and the other lead to each jack, one at a time. The needle should not move when the jacks are touched.
The headsets and D-Sub connectors "FUSELAGE" and "OPTIONS" should be unplugged during this test.

Going thru front of panel, batt disconnected, backup batt disconnected. Used digital on ohms, crossed probes reads open, test with fuselage and options disconnected each headphone jack reads SHORT. Aux jack also. SV plugged in minus usb plug and backup batt.
 
Doug, I am not sure if I understand you correctly. You said that crossed probes reads open. When ohmmeter probes are touching each other, the display should read close to zero ohms, in other words, closed, not open.
With headsets and fuselage and options plugs disconnected, and the meter connected between airframe and headset jacks, the meter should read infinity aka open.
 
If the headset jacks are confirmed to be insulated from the airframe, try disconnecting the GPS D-Sub connector from the AV-50000A to see if that eliminates the noise.
 
Doug, I am not sure if I understand you correctly. You said that crossed probes reads open. When ohmmeter probes are touching each other, the display should read close to zero ohms, in other words, closed, not open.
With headsets and fuselage and options plugs disconnected, and the meter connected between airframe and headset jacks, the meter should read infinity aka open.

Crossed probes reads SHORT and either probe in any of the 4 headphone jacks with the other probe touching an airframe screw reads short too!

Probes not touching anything reads open
I can see light brown washers on each jack against the airframe
 
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Did I do the test correctly? I will have to crank it up, do I put everything back in order to try the gps disconnect test ?
 
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If the headset jacks are confirmed to be insulated from the airframe, try disconnecting the GPS D-Sub connector from the AV-50000A to see if that eliminates the noise.

Unable to reach gps dsub thru front. Pulled power and gps connector from gps backside. I can See a few copper strands back at gps sub coming out of top of connector I can not get to. Should I roll it out and try anyway?
 
Doug, lets to the easy tests first. Connect the fuselage and options back onto the AV-500000A and disconnect the GPS D-Sub and see if the noise goes away.
 
If the headset jacks are confirmed to be insulated from the airframe, try disconnecting the GPS D-Sub connector from the AV-50000A to see if that eliminates the noise.

Semi good news. Seems like disconnecting the 496 cleared up the noise except transponder altitude reporting. Should I reconnect pins 2 and 20 to the fuselage dsub or wait until I redo the gps dsub which I think was the whine culprit?
 
Do one thing at a time so that you will know what the problem is.
A ground loop isolator between the GPS and AV-50000A might help.
 
Do one thing at a time so that you will know what the problem is.
A ground loop isolator between the GPS and AV-50000A might help.

Joe I can see a inch diameter round opaque plastic lifesaver looking thing with black gps wire/connector wrapped thru it about two rounds. It looks like it's between the gps and dsub.
 
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Doug, evidently someone else built your plane. Maybe the toroid was an attempt by the previous owner to eliminate the noise. Buy a ground loop isolator and install it in series with the GPS audio.
I suppose that I wasted your time checking to see if the headset jacks had continuity to the airframe. That test is only valid if ALL of the jacks have insulating washers. Even if only one jack is touching the airframe, the ohmmeter will show continuity to every jack since their ground wires are all connected together. If fixing the GPS ground loop does not completely eliminate the noise, then insulating every audio jack from the airframe might be helpful.
I did not realize that the transponder had audio altitude reporting (post #70).
 
Doug, evidently someone else built your plane. Maybe the toroid was an attempt by the previous owner to eliminate the noise. Buy a ground loop isolator and install it in series with the GPS audio.
I suppose that I wasted your time checking to see if the headset jacks had continuity to the airframe. That test is only valid if ALL of the jacks have insulating washers. Even if only one jack is touching the airframe, the ohmmeter will show continuity to every jack since their ground wires are all connected together. If fixing the GPS ground loop does not completely eliminate the noise, then insulating every audio jack from the airframe might be helpful.
I did not realize that the transponder had audio altitude reporting (post #70).

Joe, thank you for allowing me to hog your time. Yes someone else built it in 2010-mid 2012 timeframe. Will install the ground loop isolator, if it works, then I'll reconnect fuselage dsab pins 2 and 20 and regain IC Aux Input.
About the transponder, no not audio altitude, but a little clicking when in ALT mode, otherwise all is quiet.
I can live with that, just happy that the RPM increasing whine has ceased.
I could use some more volume with the aural warnings. I'm at 100% in the system setup module. I'll turn the L and R EFIS pots to the left a smidgen to increase volume level if I read the KAI correctly.
 
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Ground Loop Iso

Airhound,
I sold my G496 but still have the Van's AV Ground Loop Iso in my scrap box. This was furnished with my original Avionics kit.

You can have it if you want it. PM me your address and a promise to pay the priority mail postage and I will send it to you tomorrow a.m. first thing.
i-vBHb4DS-L.jpg
 
The clicking noise from the transponder might be caused by a bad connection at either end of the antenna coax. Also check the antenna mounting.
 
Portable GPS and the Skyview System

All,
I have a couple of questions about portable gps installations in general and noise they may have caused when installed in Skyview equipped RV12s, but first some background.

With Joe's help I managed to mitigate noise in my headphones. It appears our process of elimination is pointing towards the Garmin 496 wiring which when disconnected no noise. And, other than an acceptable clicking which might have to do with the transponder antenna cable, will check that next, wearing headphones is nice again for both pilot and passenger. Tony is kindly providing me a ground loop isolator to plug in line with the gps wiring and see if that clears up the noise before writing off the installation of the 496 or rebuilding the wiring. We'll see.

My questions: I notice on later ELSA RV12 Skyview builds there is no call for portable gps. Is this because we've all gone to Foreflight or Pilot or Wingx and there is no need for an portable/backup in that regard? And are we asking for problems when adding electrical complexity by installing/wiring portable gps's to the SV/RV12 Sytem? Are the Garmin X96 portable gps's the only ones Vans provided the ground loop isolator because they are the only ones they planned to use before SV....what about 660s or 796s with all their wires and cables is there an isolator for those portables as well?? Anyone have noise with them?

Any light you can shed on the topic is helpful and appreciated.
Thank you fellow pilots and maintainers.
 
The GPS x96 was sold with the D-180 system. The reason Van's does not sell a portable GPS with the RV-12 avionics anymore is because it is not needed. The SkyView system has its own GPS. This issue has nothing to do with ipads.
I would not let the possibility of problems deter me from installing desired avionics. Most problems can be solved.
The alternator and strobe noise heard in the headsets is due to the audio output of the GPS, not due to the navigation function. I do not know if other brands or models of GPS have ground loop noise issues.
Actually I have found the 496 audio to be rather annoying. Especially when it yells, "Terrain, terrain, TERRAIN, pull up, pull up, PULL UP.
An option is to leave the audio cable disconnected.
 
GPS X96 & SV history?

Van's never offered the Garmin X96's with SV kits. During the awkward transition period between the D-180 and SV there was one sheet in the Sec 42D SkyView Upgrade plans that included a template for cutting the SV center panel for the Garmin GPS. I think that the assumption was that some of those doing the SV upgrade already had a X96 and might want to use it. There were no wiring harness furnished with the upgrade kit to use the X96 with SV. You would have had to wire it yourself. No other portable GPS's were offered.
i-LvHkjvC-L.png


The Ground Loop Iso was furnished with the D-180 avionics kits. There was no support for other later portable GPS's.

I think most of the D-180 planes with the X96 installed don't have audio problems due to the GPS, at least not reported here very often, so the isolator might solve the problem.

I agree with Joe, if you like your Garmin GPS you should keep it. But I also agree that a backup GPS is not needed with SV. The Garmin data base upgrades are a pain to find, and load into the X96 and they are expensive. Plus you have to remove the GPS and connect it to the internet via a computer. None of that BS is needed to update your SV database for free every month with a USB stick.
 
Concur, if the GLI works I'll keep her. If not then out she comes. Then what to do with the bigO hole in the panel? Just short of replacing the panel I might try to install an airgizmo in place of the 496 for my Aera 560 and not hard wire it in. I think garmin still supports it? How's that sound.
 
Concur, if the GLI works I'll keep her. If not then out she comes. Then what to do with the bigO hole in the panel? Just short of replacing the panel I might try to install an airgizmo in place of the 496 for my Aera 560 and not hard wire it in. I think garmin still supports it? How's that sound.
I think I would cosider the Garmin Aera 660. The footprint is almost the same.
One sweet little unit with great reviews.
 
OK Driftdown!

Do you know if the 660 uses a remote antenna like the x96's, is there a plug-in for one somewhere or is the antenna just self contained?
 
This was in an RV6 I sold 5years ago. It's been resold again since my sale, and don't know whether it's still installed or if the current owner moved to a different unit.
 
OK Driftdown!

Do you know if the 660 uses a remote antenna like the x96's, is there a plug-in for one somewhere or is the antenna just self contained?

Recommend you go to the Garmin website.

There are two antennas they recommend for the Aera 660.

1) Low-profile Remote Antenna Part # 010-10052-05 ($99.99)

2) GA 25MCX Remote GPS Antenna (Low Profile) Part # 010-10702-00 ($31.49)
 
The GPS x96 was sold with the D-180 system. The reason Van's does not sell a portable GPS with the RV-12 avionics anymore is because it is not needed. The SkyView system has its own GPS. This issue has nothing to do with ipads.
I would not let the possibility of problems deter me from installing desired avionics. Most problems can be solved.
The alternator and strobe noise heard in the headsets is due to the audio output of the GPS, not due to the navigation function. I do not know if other brands or models of GPS have ground loop noise issues.
Actually I have found the 496 audio to be rather annoying. Especially when it yells, "Terrain, terrain, TERRAIN, pull up, pull up, PULL UP.
An option is to leave the audio cable disconnected.

Joe, reading about installing a dynon 2020 GPS has me wondering if the 496 and dynon 250 gps are wired to the same dsub that goes to the only gps connector in the AV 5000 and therefore causes noise?
 
It is not a design problem because your system is the only one with a noise problem. You brought up an important point. Since both GPS receivers connect to the same D-Sub, which one is causing the noise? (assuming you have both) Do you know for sure it is the 496 and not the 250?
 
I disconnected the 496 wires from the 496 and that noise stopped. I can't get to the 250's wiring to see what happens there yet. I just have the transponder interigation clicking to check now. What am I looking for other than loose antenna and connector?
 
Check the transponder antenna mounting to be sure it is grounded.
Check the voltage regulator case ground and battery negative ground. There should not be any paint on the sheet metal that could interfere with current flow.
 
Check the transponder antenna mounting to be sure it is grounded.
Check the voltage regulator case ground and battery negative ground. There should not be any paint on the sheet metal that could interfere with current flow.

Joe, PTT causes EGT spike. I noticed the amount of spike relates to what frequency is being transmitted on. The higher the freq the hire the spike. Also dynon indicated my ems serial number is one which was sensitive to RF interference And to send it in for upgrade. I havent had the opportunity to do the prescribed panel continuity check, but will. Does the above situation ring any bells?
 
Mauritz,
The SL40 has a built-in intercom. Perhaps that function was turned on before adjusting the sidetone, and now the SL40 intercom function is shut off.
Although I have never tried it, the Flightcom 403 intercom should work with the radio shut off. So with the radio shut off, can you still hear yourself talk? Can the passenger hear himself talk? I tell my passengers to keep the microphone close enough to kiss. And if they can not hear themselves talk, then neither can I.
Does the intercom break squelch when the knob is turned clockwise?
Is the intercom switch up in the ICS position?
Are both headsets stereo?
Have you tried other headsets?
The intercom works best when both headsets are the same brand and model.
Joe,
Should one or the other IC capability be turned off and not both be on?
 
We were chasing this very issue for the last several weeks (Skyview/Flightcom 403/SL40).

First I tried pulling pins 18 & 19 from the intercom connector, which worked besutifully until it became evident that this also disabled all of the Dynon aural alerts.

I spent a bit of time looking through wiring diagrams until I stumbled upon the page describing the initial Dynon audio setup. Eureka! Spent an hour or so fine tuning the EFIS (L) and EFIS (R) pots on the side of the AV5000, and I'm quite happy with the result.

The book actually has you practice adjusting the pots using an iPod connected to the aux input to get a feel for adjusting them before adjusting the EFIS L&R pots.

The manual specifically mentions the noise generated but the Skyview, and how we need to turn down the EFIS audio pots on the AV5000 until we can hear the aural alerts, but not the background noise. The pots have a 25 turn range, so finding the sweet spot took some time. Eventually, I gave up and turned the pots fully CW until they bottomed, and worked them out 1 turn at a time until I had audio again. The rest of the time was spent fine tuning them so I had the same volume in each ear (I had to flip a dip switch to get stereo audio in my headset. Once done, I went back to mono, as I use the headset in other airplanes that aren't wired for stereo audio).

Getting at the pots is a bit of a challenge,and I had to pull the glare shield to gain access. They're located on the right side of the AV5000. One could pull the screen instead, but you'd have to reconnect it every time to check the audio levels. I had to adjust the pots by feel, but it's doable, if not necessarily easy.

Now I can fine tune the Dynon alerts in the software and have essentially no background noise in the headsets.

Hope this helps someone.
I would like to raise the volume of the EFIS alerts (a tad), my SV setting is at 100%. I have the avionics bay open, should I use my iPhone aux music to test EFIS pot adjustments checking for increased volume as I turn the pot or are adjustments more problematic than just turning the pot screws in or out? Thank you!
 
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