COM reception problems

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diamondchad
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Re: COM reception problems

Post by diamondchad »

Thanks everyone. Good information indeed. Nothing yet. I will let you guys know when we find the culprit.
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diamondchad
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Re: COM reception problems

Post by diamondchad »

Audio panel in the G1000? Or in the rack? What is pricey?
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Diamond_Dan
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Re: COM reception problems

Post by Diamond_Dan »

The audio panel sits between the PFD and the MFD. Was $1350 installed for a swap with a refurb unit but that included some troubleshooting time.
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diamondchad
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Re: COM reception problems

Post by diamondchad »

Ok, it was the mis-gapped plugs and/or the old plug wires causing the terrible static. I called Denny at Electroair and he suggested I replace the plugs and the wires. Old wires (blue) were 1000 ohms /ft, new wires (red) are 5000 ohms /ft. I don’t know which fixed the problem but radio is nice a quiet now. When I had the engine overhauled, the shop installed new conventional plugs. The gap on these were too small. Ordered new correctly gapped plugs from Denny and all is well.
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Pascal
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Re: COM reception problems

Post by Pascal »

Wow, I would never have thought of that. Thanks for sharing this Chad !
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nrenno
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Re: COM reception problems

Post by nrenno »

I starting having problems with the radio on my 2005 DA40. Initially, sporadic scratching noise would occur briefly and then disappear. On a flight a few weeks ago, the noise started and did not go away. I could barely hear the controllers and was unable to transmit. I retuned home with 7600 on the transponder.

My mechanic replaced the PTT switch and I made two local test flights without any problems. However, I noticed that turning the avionics master on would cause a short delay between pressing the PTT and hearing the carrier. This delay does not occur when only Comm 1 is active (before turning the avionics master on). I do not remember if the delay is normal.

When doing ground check in preparation for a flight this morning the scratching noise returned, and I was not able to transmit except when turing the avionics master off and using only Comm 1. I decided to put the plane back in the hangar.

Based on the comments in the previous posts, it appears that the problem is likely in the audio panel. Should I go ahead and just replace it?

Thanks,

--Nilton
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Karl
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Re: COM reception problems

Post by Karl »

Most avionics issues I come across can be resolved by re racking the unit.
Remove the com box, inspect the pins to ensure no damage, clean with good quality contact cleaner then reinstall.
This is the quickest, cheapest thing to do before paying mechanics or ordering replacement parts. It fixes most issues.
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Karl
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Re: COM reception problems

Post by Karl »

Recently we have been getting more and more static problems and it was becoming difficult to diagnose.

Our DA40 and DA42 are now 12 years old and operate over the sea every flight. We have been finding corrosion in the bonding system despite passing the bonding test.
Corrosion at the static wick mount point is readily visible and easily fixed but we have also found bad corrosion on the bonding strap at the inner end of tailplane rear spar, behind the elevator. It is not easy to access and impossible to inspect without removing the elevator which will require an engineer sign off.
NOTE. This is on DA40 and DA42 I am not sure if the bonding system is the same on the DA20.
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nrenno
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Re: COM reception problems

Post by nrenno »

Thank you, Karl! We will do the contact cleaning first. Diamond Customer Service also suggested swapping the GIA units to see if the problem moves from Comm 1 to Comm 2.
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