Spare / Loaner AV-50000 due to intercom and radio noise ?

[snowsam]

Hello,

We have a 2014 RV-12 that has developed noise in the intercom and radio reception. It is like things are a little fuzzy (late 70s-early 80s audio). Everything can be heard, but it is just a little not clear. In addition, the intercom is more prone to feedback (squealing). You can't get much more than 60% on the intercom volume before it starts to ring. Once that feedback ring starts, you have to turn down the intercom until it does not, or it will interfere with any communication.

We have the GTR200 radio/intercom and have already switched units and confirmed the problem persists. Occasionally in flight there is a quiet "pop" and the intercom and radio return to being crystal-clear and crisp. I can then reach under the panel and "tap" under the AV-50000A and the crisp sound goes away and the fuzziness returns. I have tried re-seating the connectors on the AV unit.

Van's suggested that it might be the AV-50000, but they are currently back-ordered. I've placed a phone order to get one when they become available.

Does anyone have one on the shelf that they want to lend/rent/sell ?

This plane is used in a flight school and so it is hard to explain to people why they can't turn the intercom way up and why things sometimes are good and sometimes not.

Thank you!

 

[rcarsey]

There is no magic inside the AV-50000.. its just a circuit board with traces and a bunch of connectors on it -- I haven't seen it, but the electrical diagram doesn't show any components inside. It might be a good exercise to disconnect all the cables going to it, remove it, open it up and inspect for corrosion on pins, traces, etc. then go at it (and all the connectors) with some electronics cleaner spray. Hopefully you can narrow it down to a particular d-sub connector that fails the jiggle test.

 

[rtlongdon]

I had, what sounds like, this exact problem in my legacy -12 about 3 years ago. It got progressively worse but came and went, all or none. I Swapped the GTR200 with a known good unit from a friend, checked the grounds, headset receptacles etc.

Reinforcing Rob's post above- in the end, I jiggled one of the d-sub connectors, can't remember which one now and the problem went away. I removed the connector found the pins had a bit of corrosion. I cleaned everything thoroughly and applied a VERY light coat of Corrosion X to the pins. After that, I took the time to disconnect all the connectors and clean and re-tighten them. I check the d-sub hold down screws at each condition inspection. I do occasionally find one or two that have loosened a bit, but nothing major.

YMMV but maybe gives a simple place to start.

 

[snowsam]

I had, what sounds like, this exact problem in my legacy -12 about 3 years ago. It got progressively worse but came and went, all or none. I Swapped the GTR200 with a known good unit from a friend, checked the grounds, headset receptacles etc.

Reinforcing Rob's post above- in the end, I jiggled one of the d-sub connectors, can't remember which one now and the problem went away. I removed the connector found the pins had a bit of corrosion. I cleaned everything thoroughly and applied a VERY light coat of Corrosion X to the pins. After that, I took the time to disconnect all the connectors and clean and re-tighten them. I check the d-sub hold down screws at each condition inspection. I do occasionally find one or two that have loosened a but nothing major.

YMMV but maybe gives a simple place to start.

Thank you. Will chase this path!

 

[NORDO Industries LLC]

I've had similar issues with my GTR200 (squealing only on certain frequencies when transmitting). Reseating the unit in the tray would fix it, but come back after a few months. Eventually I put a dab of Loctite 242 (the blue one) on the locking screw on the bottom of the radio, and the issue went away.

 

[seagull]

I've had similar issues with my GTR200 (squealing only on certain frequencies when transmitting). Reseating the unit in the tray would fix it, but come back after a few months. Eventually I put a dab of Loctite 242 (the blue one) on the locking screw on the bottom of the radio, and the issue went away.

I had the exact problem with my GTR-200. Reseating it fixed it for a few months then it was back. My solution was to look at the bottom of the radio where it contacts the tray. There were rub marks in the aluminum. I first added scotch tape over the rub areas and that solved it for about 4 months then it was back and the tape was rubbed through. The last time I used a nylon tape the kind that is used on the flaps on the RV-7. That was a year ago, no issues since.

 

[snowsam]

For those wondering what the internals of the box looks like, here are some photos.

The top board is just circuit traces and then a set of pins connects to the lower board, which does have chips and capacitors, etc. The lower board has the audio pots and the trim rate pot on it. There is also a small dedicated cooling fan (not pictured).









Unfortunately, the circuit board repair guys who I had look at the boards did not find anything suspicious. And all the connectors in and out looked good.



(Due to my previous testing) I'm still thinking the problem is inside of the AV-50000A. But since Van's is not expecting more until October (hopefully), I am left with chasing other options too.

Again, if anyone has one that is not in use, I'd love to rent/borrow/buy it from you so that I can try to determine if the issue is in the unit or somewhere else.

In the meantime, I am still chasing various wires around the plane, looking for any nicks, wear, wear in the intercom jacks, the above suggestion(s) about the radio grounding, etc.

Thanks!

 

[MMiller]

This may not be the point of failure causing your problems, but it is suspect.

Looking at the pictures, that bottom PCB fails a visual solder inspection. All of the “through hole” hand solder joints are awful, insufficient solder, cold joints, splatter, and the board wasn’t cleaned of flux.

Since you didn’t mention issues specific to ONLY the right or left audio, I would assume the problem is in the mono audio circuit (the Vans board processes them separately and they are summed/mixed in the intercom) Looking at the board layout I’m guessing the left IC is the mono audio amp. I would carefully inspect all the “through hole” joints (the areas circled) paying extra attention to the mono audio amp.