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Audio Problem with 2nd Nav/Com

2006-07-10 20:17:06

Audio Problem with 2nd Nav/Com

I am having a problem with an MX-170B Nav/Com in the #2 tray. The unit was recently repaired and seemed to work OK when I first reinstalled it. After having some unrelated panel work done, the volume on the #2 Com was barely audible. The #1 radio, also an MX-170B, works fine. I swapped the two radios and the problem remained with the #2 tray, so the problem does not appear to be the radio.

I have a King KA-134 audio panel. I removed it from the tray, but it appears to be only a switching device. Does anyone know how the amplification for the radios to the headsets is handled? Also, I notice that the aircraft speaker does not work when I switch from Phones to Speaker on the audio panel (SPK button pressed). I don't know if this is related as I just discovered that the speaker doesn't work. Any help or advise would be appreciated.

Thanks

Jon Plaxton

Jonathon Plaxton: jplaxton00; 186 Posts

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2006-07-12 23:55:27

Re: Audio Problem with 2nd Nav/Com

The 170B puts out a low(headphone) audio that is fed directly to the headphones or intercom via the switch panel.

Dave Hainline: Guest; Posts

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2007-08-15 13:21:01

Re: Audio Problem with 2nd Nav/Com

I had my MX 11 to the mfg twice, neither repair fixed the problem, loosing power! I had the power pin in the slide in connector replaced. It has been working for 3 months without a problem. It was not an easy job, but worth the effort.
BobS
As a test, try this. Get a long bread knife. Long enough to reach the connector in the fixed tray. Buy some fine 400 grit wet/dry sand paper, the black smooth stuff. Tape it to both side of the end of the knife. Insert the knife into the connector and burnish the contact points on the connector. Clean by taping clean white paper to the knife end. re-burnish the connectors. If this improves your problem plan to replace the contacts on the connector.

Guest: Guest; Posts

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2007-08-16 18:00:14

Re: Audio Problem with 2nd Nav/Com

Hi Bob;

I had forgotten about this post. It turned out the problem was with me. I finally took the plane to the local radio shop. The tech pushed the #2 Nav/Com another 1/8 inch into the tray, and it worked just fine. Seems the bottom mounting tray was installed 1/8 inch farther into the stack than the top tray. I was pushing the radio in to where the face lined up with the top radio, so some of the connector pins were probably not engaging. So I got to feel stupid that day for only $60! Beats the time I shorted my electical system trying to replace a landing light switch and got to feel stupid for $700. That feeling lasts a lifetime!

Jon