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  #11  
Old 03-15-2019, 01:36 PM
alexe alexe is offline
 
Join Date: May 2013
Location: Temecula, CA
Posts: 259
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There is normally a large filter capacitor (around 22,000 mf) on the output side of the voltage regulator. On the RV-12, I believe that capacitor is located inside the switch/fuse module. Itís purpose is to smooth AC noise on the electrical bus. It is not unusual for filter capacitors to fail over a period of time in use. That might be your culprit. You can temporarliy install a second filter capacitor of equal value between the regulator output (B & R leads) and ground. The positive terminal of the capacitor goes to the regulator output, the negative to ground. Give it a whirl and see if it solves your issue.
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RV-12 #120758, N912AE
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  #12  
Old 03-15-2019, 04:07 PM
bobg56 bobg56 is offline
 
Join Date: Nov 2018
Location: Peachtree City, GA
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Would a good noise cancelling head set help?
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  #13  
Old 03-15-2019, 07:37 PM
backcountry backcountry is offline
 
Join Date: Dec 2015
Location: Houston, Texas
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I had already went looking for the capacitor and thought it was missing and thought I had found the problem but I found it was in the switch/power module per the wiring diagram. Yes it is possible that it has failed. It might be worth putting alligator clamps on the capacitor and temporary checking it out.

I already use a Boise noise canceling headset.
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  #14  
Old 03-15-2019, 07:57 PM
alexe alexe is offline
 
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Location: Temecula, CA
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Larry,
Yes, I think it would be a good thing to try. You might consider bugging into the regulator output at the regulator rather than tearing into to the power module and using alligator clips (just for this test). You should be able to find a filter capacitor online fairly cheap. Make sure it has a voltage rating above 25 volts. Fifty volts would be more than adequate. It should have a capacitance rating somewhere between 20,000 and 30,000 microfarads. Please let us know how it goes for you.
Alex
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Alex Erdelyi
RV-12 #120758, N912AE
Flying as of 4/28/15
Paid through December, 2019
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  #15  
Old 03-15-2019, 09:01 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,778
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Here is an easy test for the ground:
With every electrical load turned on including something plugged into the power
outlet, measure the voltage drop between the battery negative terminal and the
radio ground (assuming the noise is coming from the radio). That voltage
should be only be a very few millivolts, the closer to zero the better.
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  #16  
Old 03-16-2019, 05:36 AM
MMiller MMiller is offline
 
Join Date: Oct 2010
Location: Babylon NY
Posts: 54
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If you think itís a bad cap, I would start here.

The 22nf ,1KV capacitor in this photo is in the Ducati regulator. Itís across the G lead input. Like other connections in the regulator, this one is also prone to fracture.



This sample had 100 hours on it.

Here is the full size image if you want to zoom in;
https://drive.google.com/file/d/0ByP...w?usp=drivesdk
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  #17  
Old 03-16-2019, 10:56 PM
backcountry backcountry is offline
 
Join Date: Dec 2015
Location: Houston, Texas
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Yes, I donít want to go into the switch module.
Plan to get a new capacitor and add the alligator clamps to temporarily clip it to the regulator terminal.
If by chance it fixes the problem the capacitor would be permanently attached.
Thanks for your thoughts.
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