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Intercom Noise

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DarnGlasairIII

Joined: 28 Aug 2010
Posts: 9
Location: Jacksonville, FL

Posted: Thu Sep 02, 2010 4:25 pm Post subject: Intercom Noise

Bob,

    

   More data points:

   I installed a portable intercom in my plane.  Its plugged in the new Pilot mic & phone jacks.  With only the internal 9v battery powering the unit, I still get the noise in my headsets, but it is tolerable.  Intercom off = no noise.  When I power the portable intercom from ships power the noise is louder, but still tolerable...barely.

    

   Any ideas now?

 

 

                Jeff Darnall

              Jacksonville, FL

              904-234-8718

                   __i__ 

   *-----o--o--(_)--o--o-----*<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

    

 

 

      

 

 

   [quote][b]

_________________
Thank you, Jeff

bgray(at)glasair.org
Guest

Posted: Thu Sep 02, 2010 4:43 pm Post subject: Intercom Noise

I’d say it’s time to look at your headsets.  

     

Bruce

 www.Glasair.org   

  

--

DarnGlasairIII

Joined: 28 Aug 2010
Posts: 9
Location: Jacksonville, FL

Posted: Thu Sep 02, 2010 4:48 pm Post subject: Intercom Noise

Bruce.  Why?  Tell me more?



I've used several different type headsets and they all have the same issue

_________________
Thank you, Jeff

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Sep 03, 2010 7:09 am Post subject: Intercom Noise

At 07:17 PM 9/2/2010, you wrote:

  	  Quote: 	
		   Bob,

  

 More data points:

 I installed a portable intercom in my plane.  Its plugged in the new Pilot mic & phone jacks.  With only the internal 9v battery powering the unit, I still get the noise in my headsets, but it is tolerable.  Intercom off = no noise.  When I power the portable intercom from ships power the noise is louder, but still tolerable...barely. 	


    Hmmmmm . . . What is the nature of the noise?

    whine, rumble, static, does it's pitch or repetition

    rate change with engine RPM. Does the noise go

    away if EVERYTHING else is off while only the

    radio/intercom pair is operating?



 

   Bob . . .    [quote][b]

bgray(at)glasair.org
Guest

Posted: Fri Sep 03, 2010 9:07 am Post subject: Intercom Noise

Trouble shooting electronic gremlins requires a systematic approach. The most important thing to remember is to only change one variable at a time.   

   

If you have swapped headsets and the noise remained, we can rule out bad headsets.  

   

I would suggest the following decision tree.  

   

<![if !supportLists]>1)     <![endif]>Test the intercom in another aircraft if possible. If the problem follows the intercom, the intercom is bad.  

<![if !supportLists]>2)     <![endif]>Test with the engine and  ALL other electrical devices OFF except the intercom. If no noise proceed to 3  

<![if !supportLists]>3)     <![endif]>Repeat 2 with engine running and ALT off.  

<![if !supportLists]>4)     <![endif]>Repeat 2 with engine and ALT on.  

<![if !supportLists]>5)     <![endif]>With engine off, turn on separately each other piece of electronics.  

<![if !supportLists]>6)     <![endif]>Repeat 5 with engine and ALT on.  

   

Get back to me with the results.  

   

Are you using shielded wire? Is the shield only grounded at one end (which is correct)?    

Bruce

 www.Glasair.org   

  

--

DarnGlasairIII

Joined: 28 Aug 2010
Posts: 9
Location: Jacksonville, FL

Posted: Fri Sep 03, 2010 7:10 pm Post subject: Intercom Noise

It is alternator noise.  Pull the alternator cb and the noise goes away.  I can also hear my flap and fuel pump motors when they run.



Sent from my iPad



On Sep 3, 2010, at 10:09 AM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:



[quote] At 07:17 PM 9/2/2010, you wrote:

  	  Quote: 	
		   Bob,

  

 More data points:

 I installed a portable intercom in my plane.  Its plugged in the new Pilot mic & phone jacks.  With only the internal 9v battery powering the unit, I still get the noise in my headsets, but it is tolerable.  Intercom off = no noise.  When I power the portable intercom from ships power the noise is louder, but still tolerable...barely. 	


    Hmmmmm . . . What is the nature of the noise?

    whine, rumble, static, does it's pitch or repetition

    rate change with engine RPM. Does the noise go

    away if EVERYTHING else is off while only the

    radio/intercom pair is operating?



 

   Bob . . .     	  Quote: 	
		  

	
 

[b]

_________________
Thank you, Jeff

DarnGlasairIII

Joined: 28 Aug 2010
Posts: 9
Location: Jacksonville, FL

Posted: Fri Sep 03, 2010 7:55 pm Post subject: Intercom Noise

Pull alt cb and no noise. No different with any radio configuration. I also get noise occasionally from the electric motors of the flaps and fuel pump when they are run. When I use the portable (9v)  intercom the noise is less, but still there.  When I use ships power, the noise is a little worse, but much less than the installed Sigtronics intercom. When I use no intercom at all I can barely hear any noise, but it is still there.



Sent from my iPad



On Sep 3, 2010, at 12:05 PM, "Bruce Gray" <bgray(at)glasair.org (bgray(at)glasair.org)> wrote:



[quote]    

Trouble shooting electronic gremlins requires a systematic approach. The most important thing to remember is to only change one variable at a time.   

   

If you have swapped headsets and the noise remained, we can rule out bad headsets.  

   

I would suggest the following decision tree.  

   

1)     Test the intercom in another aircraft if possible. If the problem follows the intercom, the intercom is bad.  

2)     Test with the engine and  ALL other electrical devices OFF except the intercom. If no noise proceed to 3  

3)     Repeat 2 with engine running and ALT off.  

4)     Repeat 2 with engine and ALT on.  

5)     With engine off, turn on separately each other piece of electronics.  

6)     Repeat 5 with engine and ALT on.  

   

Get back to me with the results.  

   

Are you using shielded wire? Is the shield only grounded at one end (which is correct)?    

Bruce

 www.Glasair.org   

  

--

_________________
Thank you, Jeff

bgray(at)glasair.org
Guest

Posted: Fri Sep 03, 2010 9:07 pm Post subject: Intercom Noise

Then the problem is an ALT diode or a wiring ground/shield error.  

   

The easiest to check is the ALT. Pull it and send it to your favorite auto electric overhaul shop.  

     

Bruce

 www.Glasair.org   

  

--

DarnGlasairIII

Joined: 28 Aug 2010
Posts: 9
Location: Jacksonville, FL

Posted: Sat Sep 04, 2010 3:35 am Post subject: Intercom Noise

Then why would I also be getting noise from my flap and fuel pump motors?

The alternator and the voltage regulators were replaced during my overhaul of the entire airplane.

I'm suspecting a ground problem.  But just how to attack it is the question.  I (think) evereything is on one common

avionics ground buss.

I suppose my attack will be as follows:

Redo all the grounds at the ground bus.

Then recheck all the power leads.

Then get a filter plan on the power and/or ground. 

(I've already put a big filter on the incoming alternator power line.)

Thoughts?

Jeff



Sent from my iPad



On Sep 4, 2010, at 12:05 AM, "Bruce Gray" <bgray(at)glasair.org (bgray(at)glasair.org)> wrote:



[quote]    

Then the problem is an ALT diode or a wiring ground/shield error.  

   

The easiest to check is the ALT. Pull it and send it to your favorite auto electric overhaul shop.  

     

Bruce

 www.Glasair.org   

  

--

_________________
Thank you, Jeff

bgray(at)glasair.org
Guest

Posted: Sat Sep 04, 2010 12:50 pm Post subject: Intercom Noise

I know you want to start digging into the wiring, and your noise from other devices indicates that there is some problems there, but PLEASE pull the ALT and take it to an auto electric shop and have them check the diodes. There is thing called “infant mortality” in this industry (out of box failure).  

     

Bruce

 www.Glasair.org   

  

--

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