Bad transmit on pilot side, but co side okay?

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shoffert
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Bad transmit on pilot side, but co side okay?

Post by shoffert »

Hello, Everyone.

I'm new the forum. I picked up 2002 DA-40 earlier this year to teach my kids to fly in, and I love it. Just a touch slower than my old Glasair iii, but a real joy to fly and I save $5k a year on insurance!

I do my best to search the forum before asking a question so I don't need to post often, but I haven't found a post about my particular problem yet. I wonder if someone has seen it before?

My pilot side radio transmissions are weak on Comm1 and Comm2 (2002 DA-40 with two Garmin 430s and the original Garmin audio panel).

The co-pilot side transmits just fine on both radios. Intercom is crystal clear from both seats, as are all incoming radio transmissions from both radios. Changing headsets makes no difference. My only trouble is weak transmissions from the pilot side.

In the hanger, I can transmit clearly to the backup radio, but airborne I have no range.

Such an odd failure...just wondering if anyone has seen it before...the solution of plugging into the co-pilot jacks and reaching over to use that button to transmit during flight is totally hilarious when your buddy is riding shotgun!

Leads are much appreciated!
-Steve
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Steve
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Re: Bad transmit on pilot side, but co side okay?

Post by Steve »

Steve:

Welcome! Most likely it is your Pilot's PTT switch or Mic jack. You can confirm this by unplugging the Pilot's headset mic plug and then trying the handheld Mic, plugged into the jack under the instrument panel. This will bypass both the Pilot's PTT switch and Mic wiring and jack. Let us know what you find...

Steve
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shoffert
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Re: Bad transmit on pilot side, but co side okay?

Post by shoffert »

Mine didn't come with the handheld...I'll start tracking one down and try it right away. I bet someone at the field has one I can borrow.

You think it could still be the pilot side switch, even though I can transmit from the pilot side, just with limited range? In the hanger, with my headset plugged in to the pilot side like normal, I can successfully transmit from the pilot side to my backup radio.
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Re: Bad transmit on pilot side, but co side okay?

Post by Sandy »

I had a weird problem like that. It turned out to be an issue in the A20’s headset mike plug. Fortunately, Bose replaced it for free at their booth at Sun N Fun.

Try switching a different headset to the pilot’a side.

Sandy
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Rich
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Re: Bad transmit on pilot side, but co side okay?

Post by Rich »

shoffert wrote: Mon Apr 13, 2020 11:06 am Mine didn't come with the handheld...I'll start tracking one down and try it right away. I bet someone at the field has one I can borrow.

You think it could still be the pilot side switch, even though I can transmit from the pilot side, just with limited range? In the hanger, with my headset plugged in to the pilot side like normal, I can successfully transmit from the pilot side to my backup radio.
Looking at the wiring diagrams I don't see the PTT being able to impede the output signal yet allow transmission, but it's worth trying a handheld just to confirm/eliminate the pilot headset mike jack.

Another thing to try is to reseat the audio panel. I've had this cure assorted weirdness that showed up in the other boxes.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rick
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Re: Bad transmit on pilot side, but co side okay?

Post by Rick »

I know you don't have the G1000, but in the G1000 config I believe there is an adjustment for pilot-side and copilot-side mic levels in the audio panel. Could there possibly be something like that in the 430 for your Garmin audio panel? Just a shot in the dark...

The only other thing I can think of would be a (near) short in the pilot-side mic jack. I wonder what the difference would be if you measure the impedance of the two mic jacks with the power off? If the pilot side was nearly zero, and the copilot side much higher, I would start there...
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shoffert
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Re: Bad transmit on pilot side, but co side okay?

Post by shoffert »

Rich...I've been thinking audio panel the whole time. I hadn't thought about cleaning and re-seating the connections. That should have come to mind.

Rick...I'll also check the mic levels...I haven't seen that affect outgoing transmissions before, but I'll try anything to stay out of the avionics shop at the moment! Volumes are great on the intercom with current settings. I see you're just up the road in Roanoke. I'm based in Asheville, NC. You should drop a line if you 're ever in town.
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Re: Bad transmit on pilot side, but co side okay?

Post by Rick »

Well.. howdy, neighbour! Likewise, let me know if you're ever up this way. And don't discount the shorted mic jack theory - I'm liking that better the more I think about it, and it's an easy test that doesn't involve a trip to the shop!
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shoffert
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Re: Bad transmit on pilot side, but co side okay?

Post by shoffert »

To close out this thread...

I pulled the PTT and found the part number on the side. I ordered an identical one online for $1.50...$5.26 with express shipping. 10 minutes to pull the switch and solder the new one on. Huge win.

Just a little oxidation on a contact can do crazy things, I guess!

-Steve
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Re: Bad transmit on pilot side, but co side okay?

Post by Steve »

Steve:

Care to share the Manufacturer/part number/source for the PTT switch? Also, how do you remove it? I'm sure yours won't be the only one to fail...

Steve
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