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RV-12 audio feedback problem

JRo

Well Known Member
I'm getting annoying static in my headset, as well as my passenger's, when I transmit on VHF. My transmissions are 5X5 on other receivers. Reception is also fine, as is the intercom. My headset works just fine in other aircraft.
Is there a "pot" I can adjust down? Any guess what my noise is from?

Also, found out the hard way that my headset (Bose A20) has a metal hinge right at the peak which actually contacts the canopy when I lift up from the seat to reach lap belt or what ever (and I'm only 5'8"). My headpiece is now wrapped in felt, so all good, but be warned.

Jim
flying 15 hours
 
Sidetone Level Adjustment
The sidetone volume was preset at the factory to what should be an acceptable level. The level
can be adjusted in the System Functions mode. To adjust the sidetone level:
1. Press and hold the Mon button for about two seconds. This will access the System Functions mode.
2. Rotate the large knob to display the Sidetone Lvl page.
3. Rotate the Small knob to change the level number. The range of the number is 000 to 255, with 128 producing one half of full rated output. A setting of 000 slaves the level to the Volume knob.
4. Press any key to exit the Setup Functions mode.
5. Select an appropriate frequency, key the transmitter, and talk into the microphone to check the level.
Above is from SL40 installation manual.
Joe Gores
 
I, too, had horrible/loud audio distortion in my headphones whenever I pushed the PTT button/transmitted (SkyView system). The simple solution was to do as Joe Gores suggests above. By setting my SL-40 "sidetone" setting to "00", my audio distortion went away, my sidetone works great, and all is good. :)

Jim -- Ahh, I remember with great fondness the good old days at RCAP ('TUTE '69 -'73). Do they still use Christmas lights in mayonaise jars for their runway lighting "system"?? -- David
 
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This forum is a great resource! I have the PTT distortion, so hopefully Joe's suggestion will fix it. However another annoying little problem is that the various flashing warnings on the Skyview cause a corresponding on-off click in the headset. This applies to things like the AP not being switched on when Skyview expects to see it on, low fuel pressure warning because the engine and fuel pump are off, maybe a Skyview calibration or backup battery check that hasn't been done yet etc. Has anyone found a way to get rid of these irritating headset clicks?
 
I do not know what causes the clicks, but there is a workaround. Turn the autopilot switch on. And set the "Inhibit Engine Alerts at Boot option" to yes, per page 7-60 of the SkyView System Installation Guide - Revision T. Are there still clicks after the alarms have been acknowledged?
 
I'll try that next time I'm down at the hangar Joe. My headsets are grounded at the fuselage floor ribs as per the older plans. I think the later kits ran a ground wire back to the panel somewhere. Wondered if the clicks might be related to that for some reason. While I manage OK with a sledge hammer and screwdriver, electrons have me baffled.
 
After my original SL-40 failed (just past warrantee, of course), and came back from Garmin after repair, it nearly deafened me the first time I transmitted. Apparently the factory procedure is to set the sideline to the middle of the manual scale, 128. The zero setting, slaving the level to the volume control, works a whole lot better.
 
My headsets are grounded at the fuselage floor ribs as per the older plans.
The headset jacks and especially the mic jacks should NOT be grounded to the floor! Insulated washers (stepped and flat) should have been included in your kit.
 
The headset jacks and especially the mic jacks should NOT be grounded to the floor! Insulated washers (stepped and flat) should have been included in your kit.
Sorry Joe. The headset jacks are correctly installed as per the plans. I was thinking of the PTT ground - senior's moment. :eek:
 
headset/ intercom problems

I have lots of sympathy with you folks having problems,- it's horrible having 'mysteries' in the electronics! Don't forget that back in September 2014 it was established that figure 2 on drawing 31b-17, revision 0,(wiring of headphone sockets) was INCORRECT. At that time, 25 Sept 2014, Scott posted that "a change notice is in work to correct the connector depiction, and resolve this problem". I am unable to see where or if the drawing WAS revised on VAN's website, so it may be that there are still many RV12s with incorrect wiring out there. I reckon it's always worth double checking that the wiring matches the schematic, and using matching STEREO headsets first, then delve further into the electronics if you have to... Hope this helps... Cheers, DEAN....
 
Good point Dean. My Skyview has the D180 conversion harness which is covered by Sections 42C and 42D. Consequently my jacks are installed as per page 31-10 (D180), not 31B-17 (Skyview). Therefore I only have isolating washers on the mic jack and not the headset jack, as only one set of these was supplied with the kit. I wonder if that's contributing to the problem?
Next question - where to get the extra washers? Are they a Vans supplied item or are they sourced from the jack manufacturer - who is...? Alternatively I guess I could shop around locally. Can't be too hard to find some, although the stepped washer is an odd one.
 
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Although mounting the headphone jack with insulating washers is a good idea, they might not cure the clicking noise. I have the D-180, so can not give good advice about the SkyView. I would make sure all of the SkyView settings are right and then fly with it. If the clicking noise goes away after acknowledging all alarms, then it is not really a problem.
 
Thanks Joe, you're right. I haven't really had time yet to delve into re-setting alarms etc. I'm about an hour and fifteen away from the airfield, so unfortunately it's not a quick trip to the hangar to try things out. I also posted a query on Dynon's website last night and true to their reputation, they have been quick to offer to help with troubleshooting. It's probably nothing major and there are workarounds as you pointed out. If I do find out what's causing the problem, I'll post it here. Thanks for digging up the washer info too. Just saw your post.
 
Passenger communication lost

Hi Joe
I have changed the settings as per Sidetone Level Adjustment instructions, this cleared the audio distortion. However there are now no coms between me and my passenger, although he can hear all the communication with other aircraft very clear.:confused:
The other aircraft operators hear my transmissions now clear.
Hope you can help
 
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Mauritz,
Do you have the SL40 and Flightcom 403, or GTR200?
Is there side tone? Can you hear yourself talk?
Did the intercom work before you changed the side tone?
 
If you have the GTR200, have you read page 3-7 of the GTR200 Installation Manual?
Intercom Enabled:
Sidetone volume may also be linked to the ICS (intercom) volume. This is
accomplished by selecting the Sidetone setting one turn counter clockwise from ?00? setting, ?ICS? will be displayed (Figure 3-5). Intercom volume is adjustable in normal mode (see Pilots Guide).
 
Hi Joe
Hi have the SL40 and Flightcom 403. There were a lot of background noise in my transmitting before I changed the sidetone settings and we could hear one another very clear. I can hear myself talk.
 
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.
 
Side Tone

I had a very similar problem and fixed it with the SL40 settings. Van's presets did not work on mine for some reason.

Stein got me going in the right direction.
 
Headset noise

Further to my previous post about the repetitive buzz/click noise I was experiencing in the headsets, I put a post on Dynon's forum. Jake (Dynon Australia) promptly responded by PM and phone to help troubleshoot the problem. He even rang me on a Saturday evening at 10:30 pm (his time) - fantastic service! Anyway, after some experimenting (eg. engine on/engine off, different headsets, disconnecting the EMS etc) to try to isolate the source of the problem, I found that the noise finally stopped when I disconnected the backup battery. I re-connected it to confirm that the battery was causing the problem. To my surprise - no more noise. Connected everything back up, powered up the system several times, flipped all the switches etc and everything works fine. Don't know what the problem was - maybe something to do with micro-Molex connector. The other issue of the SL40 feedback was easily fixed by Joe's suggestion, so all is well again.
 
Fixed now...

I spoke too soon in the previous post. While Dynon's support has been excellent, the problem turned out not to be a fault in the Skyview.

To go back about three months, I've had a constant `bzzt....bzzt...bzzt' sound in my headset repeated at exactly one second intervals. Both pilot and co-pilot sides were affected. The sound level stayed constant despite adjusting the intercom squelch and volume knobs, and was unaffected by the transponder, radio, autopilot or lights. At first I thought the sounds were related to the flashing warning signs on the Dynon, but later realised they were exactly timed to the digital clock on the display. The noise would start as soon as the boot sequence got to `starting network manager'. If I unplugged the GPS antenna from the AV5000 module so that the system couldn't pick up the time signal from the satellites, the clock would not appear and neither would the noise. Dynon initially thought it might be related to the transponder, but neither disconnecting the transponder, the EMS, or anything else seemed to make any difference. If the clock was active, so was the noise. The only way to get rid of it was to disconnect the GPS antenna, which wasn't really a good solution. However, flying with the noise wasn't an option either as it was as irritating as a dripping tap.

However, I got lucky this afternoon when a local electronics guru happened to be at the field. He spent a couple of hours trouble-shooting the system, checking the Skyview settings, the radio, tracing the wiring diagram, pulling pins, etc, until he eventually discovered that the noise was apparently being generated by interference between the music jack wires and the tunnel harness, which runs to the ADAHRS mounted in the tail cone. When the GPS antenna was connected, it appears that EMF generated in the network cable was being fed into the audio wires that run close to the cable in the tunnel, and was therefore audible in the headsets. Disconnecting the two audio wires fixed the problem. It was a simple solution, but tracking down the cause has been a very frustrating exercise. Glad it's been fixed now.
 
Valuable info

Hi Robert, - That's an important post, - for me any way! My aircraft has EXACTLY the same symptoms as you described so well. I had figured out that the regular pulsing noise & hash was coming from the Skyview, as it went away when the SV was turned off, but I had no idea where it was getting in to the audio system. Can you please advise exactly where & how you disconnected (cut?) the music input wires?
I had not planned to ever use the music input anyway,so no loss there, I suspect when I get my aircraft flying,(soon), there will be quite enough inputs of various types to fill my brain without music as well! Thanks very much, DEAN
PS Congratulations on your recent first flight!!
 
I had a somewhat similar noise issue with my Garmin GTR-200 as intercom (not sure what you're using). I ended up (at Van's suggestion - thanks to Rian) simply turning down the audio input volume level - took care of the problem. Apparently the audio input is low-impedance and very sensitive to noise from external sources (in my example thought to be strobe lights and alternator - one noise source pulsed with the strobes and the other "whining" noise varied with engine RPM).
 
Turner, mine is the Garmin SL-40/Flightcom 403 combination. Dean, we pulled pins 2 and 20 from the tunnel connector where it plugs into the AV5000 (but check your wiring diagram to be sure). It was a long afternoon, and it was getting dark when we finally worked out what the problem was. I think it has also cleaned up the other minor Skyview hum and other little extraneous background noises that I was hearing before, but that weren't really a problem. The really annoying sound was the clock pulse. I'm at work again today so will have to wait for the weekend to check thoroughly. The music jack wires should be shielded according to the electronics guy. I haven't had time yet to see whether they are or not, but I'm not too bothered as I wasn't planning to use the jack anyway.

It's nice to finally have the plane in the air. My test pilot, who normally flies a PC12, said it's `a great aircraft and flies beautifully'. Hope your test flight goes well.
 
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Great to hear it's 'fixed' Rob. One thing to consider is although you may have shielded wire on the audio IN jack it may not have the shield grounded at the Intercopm end which is a must for all audio :)

I trust the test flying will be a bit 'quieter' now :)

Jake J
 
Yes, thanks Jake. Fingers crossed. I hate electrical problems even more than fibreglass. At least I can see the fibreglass.
Cheers
Rob
 
I posted this issue on the AeroElectric List to get other opinions. The consensus is that the music jack, or any audio jack, should NOT be grounded to the airframe. The music jack should be insulated from the airframe with a dedicated ground wire going back to the intercom. Any signal that gets amplified is especially vulnerable to noise. Audio circuits should NOT share current paths (ground) with other aircraft circuits. Sets of wires that are twisted are less vulnerable to noise than parallel wires. For those who do not want to disconnect the music input circuit, I suggest that the jack be insulated from ground and that the 3 wires (ground, left, & right) be twisted together.
 
Great to hear it's 'fixed' Rob. One thing to consider is although you may have shielded wire on the audio IN jack it may not have the shield grounded at the Intercopm end which is a must for all audio :)

I trust the test flying will be a bit 'quieter' now :)

Jake J

Joe - just wanted to make my statement clearer. All audio shielded wiring should be grounded at the Intercom ground bus (on the Intercom itself)
Just follow the manuals & particularly the PS-Engineering ones &- they are the best GA audio people IMO :)

Jake J
 
intercom noise

Hi Robert & all, - it wasn't that easy, -I pulled pins 2 & 20 on the fuselage plug, & there was no difference in the noise at all! After a week of all sorts of theories & head scratching, I pulled the music input pins right at the intercom (pins 18 &19): Aaah, absolute silence, intercom, radio etc all working beautifully! So, was the noise being induced in the Van's connector box, or were pins 2 & 20 on the fuselage plug not the correct ones? Being a computer dummy, I have not been able to see the circuit diagram, despite following the Van's instructions carefully.. Anyway the final result is excellent: clear radio & intercom, & NO noise... Cheers, DEAN....
 
Good information, Dean. I still don't know what caused the noise, only what finally made it stop after weeks of frustrating trial and error experimenting. Do you have the conversion harness wiring or the later Skyview wiring?
 
intercom noise

G'day Robert, I, (luckily I think) have the later Skyview 1000 system.... Cheers. DEAN....
 
Thanks Dean. I have the D180/Skyview conversion harness so that may explain why the pins I isolated didn't work in your case. At least you've fixed it, and hopefully the information may help others, although it doesn't seem to be a common problem in the RV-12 community. Maybe it's got something to do with living on the bottom of the planet. :confused:
 
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.
 
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Where in the manual(s) did you find the instructions for the setup of the pots on the SV5000? I've been searching the Skyview installation manual but have not found the instructions you reference. Thanks for the help.
 
Joined the group - -

My I/C has made some noise that I finally got around to chasing down. Thanks to Joe Gores for leading me to this thread. Music wires have been the problem. Disconnected. Seems great now.

Thanks Joe,
 
I had a somewhat similar noise issue with my Garmin GTR-200 as intercom (not sure what you're using). I ended up (at Van's suggestion - thanks to Rian) simply turning down the audio input volume level - took care of the problem. Apparently the audio input is low-impedance and very sensitive to noise from external sources (in my example thought to be strobe lights and alternator - one noise source pulsed with the strobes and the other "whining" noise varied with engine RPM).

Turner,

I'm hopeful, please explain in detail 'simply turning down the audio input' where do you do that? In Skyview or a SV5000 pot...if pot which way do you turn the screw??

Thank you,
Doug in IL
 
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Turner,

I'm hopeful, please explain in detail 'simply turning down the audio input' where do you do that? In Skyview or a SV5000 pot...if pot which way do you turn the screw??

Thank you,
Doug in IL


On the GTR-200 it's a menu option - I no longer have the RV-12, but I think you just press the menu button and find the "audio" input, then use the knob on the right to lower its volume. The audio input looks like a "music" symbol as I recall.

If you don't have GTR200 sorry not sure how it works on Dynon (I had G3X) but I think GTR200 is the standard radio with either EFIS.

TB
 
Thank you for your response...My system is: SL40, Flightcom 403MC, SV
I apologize for not specifying that up front...My bad!
 
Are all microphone jacks and headphone jacks and music jacks all mounted with insulating washers and not touching sheet metal?
 
RV12 audio distortion

Are all microphone jacks and headphone jacks and music jacks all mounted with insulating washers and not touching sheet metal?

Hey Joe! I have many of the same symptoms as described in this thread. I have the SV conversion harness and the headset/mic jacks are grounded to the fuselage. I know I need to install the insulating washers but do not know where to run a ground wire. Can you help me with this?
Scott L.
 
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.
 
Joe,
I do not understand the exact cause of the very noticeable hum which changes with engine RPM and the effect of pulling IC pins and/or adjusting pots, but am willing to experiment....I believe my ELSA headphone jacks are properly grounded.

Following is me reading multiple posts which purport noise fixes. I am trying to determine which if any will fix my very noticeable variable, with engine RPM, humming noise issue. My IC system is an SL40/403MC/ELSA:

1. I read-Pulling IC DSub pins 18 and 19 in a Flightcom IC/SL40 system will disconnect the Aux IC input and clear up other systems noises...The idea is the Aux wires run the tunnel to the Aux jack.....and that path picks up noises from the various other wires running parallel (AP servo/AHARS/fuel etc)
2. I also think I read (probably in a confused state) - that by pulling those pins not only takes out the Aux IC input and noises, but also aural warnings...(not sure how that all works that it affects the aural warnings)
3. and I also read...a suggestion that adjusting AV5000 EFIS L/R Pots makes the noise more bearable rather than disconnecting pins.

I'm ready to adjust pots and/or pull pins 18 and 19 to loose the noise....but don't desire to create more problems if I can accurately narrow down potential fixes.

Thank you!
Doug in IL
 
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Doug, by properly grounded, do you mean that the jacks are mounted with insulating washers? The mic jacks especially should not touch sheet metal.
If you do not use the music input jack, I recommend disconnecting it by pulling pins 2 & 20 from the "Fuselage" connector on the AV-50000A CONTROL MODULE. Doing that will not disable audio inputs or warnings from other sources.
If a Garmin 396 or 496 is installed, is there an "AV Ground Loop" also installed? If not, installing one might help. Van's sells them.
I have a D-180 system and am not familiar with the AV50000A EFIS L/R pots, so can not comment on adjusting them.
 
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