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jumpimg gauge needles

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bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sat Jul 20, 2013 10:02 am Post subject: jumpimg gauge needles

i know this has come up before but i can't find it. a friend with a 912 has the needles on his falcon engine gauges jumping and twitching while engine is running. are there places to look at to fix this? he has been told to run wire from regulator to battery terminal, not just to bus. anything else come to mind?

   

   bob noffs

  [quote][b]

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jul 20, 2013 12:06 pm Post subject: jumpimg gauge needles

At 01:01 PM 7/20/2013, you wrote:

 	  Quote: 	
		  i know this has come up before but i can't find it. a friend with a 

912 has the needles on his falcon engine gauges jumping and 

twitching while engine is running. are there places to look at to 

fix this? he has been told to run wire from regulator to battery 

terminal, not just to bus. anything else come to mind?




	


   Does the jumping stop with the alternator

   OFF?



   Can you describe the architecture of his

   ground system? Do all the gauges wiggle

   or just some . . . and what do they display.

   Are there oil, coolant or fuel SENSORS

   that ground locally . . . in others words

   ground where they mount and then carry their

   data off on a single wire?



   Bob . . .

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bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sat Jul 20, 2013 1:15 pm Post subject: jumpimg gauge needles

bob, i know the answer to some of your questions but i will track down arnie and get answers for them all and get back to you.

  bob noffs

 On Sat, Jul 20, 2013 at 3:05 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

  [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>  



At 01:01 PM 7/20/2013, you wrote:

  	  Quote: 	
		  i know this has come up before but i can't find it. a friend with a 912 has the needles on his falcon engine gauges jumping and twitching while engine is running. are there places to look at to fix this? he has been told to run wire from regulator to battery terminal, not just to bus. anything else come to mind?

 

	




  Does the jumping stop with the alternator

  OFF?



  Can you describe the architecture of his

  ground system? Do all the gauges wiggle

  or just some . . . and what do they display.

   Are there oil, coolant or fuel SENSORS

  that ground locally . . . in others words

  ground where they mount and then carry their

  data off on a single wire?



  Bob . . . 

  ===========================================

_ities such as List Un/Subscription,

 www.matronics.com/Navigator?AeroElectric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ======================ttp://forums.matronics.com/" target="_blank">http://forums.matronics.com

 ======================       -Matt Dralle, List Admin.

 ================================



 



[b]

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sun Jul 21, 2013 6:48 am Post subject: jumpimg gauge needles

hi bob,

  ok, got the info. mitchell gauge for water temp., oil temp and oil pressure. these 3 gauges all twitch, water temp. the worst. the electric uma tach and the elec. vdo fuel gauge work fine. all gauges have a separate ground wire back to a a common ground.

    bob noffs  

 On Sat, Jul 20, 2013 at 4:15 PM, bob noffs <icubob(at)gmail.com (icubob(at)gmail.com)> wrote:

 [quote] bob, i know the answer to some of your questions but i will track down arnie and get answers for them all and get back to you.

  bob noffs

   On Sat, Jul 20, 2013 at 3:05 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

   	  Quote: 	
		  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>  



At 01:01 PM 7/20/2013, you wrote:

  	  Quote: 	
		  i know this has come up before but i can't find it. a friend with a 912 has the needles on his falcon engine gauges jumping and twitching while engine is running. are there places to look at to fix this? he has been told to run wire from regulator to battery terminal, not just to bus. anything else come to mind?

 

	




  Does the jumping stop with the alternator

  OFF?



  Can you describe the architecture of his

  ground system? Do all the gauges wiggle

  or just some . . . and what do they display.

   Are there oil, coolant or fuel SENSORS

  that ground locally . . . in others words

  ground where they mount and then carry their

  data off on a single wire?



  Bob . . . 

  ======================s List Un/Subscription,

 www.matronics.com/Navigator?AeroElectric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ======================ttp://forums.matronics.com/" target="_blank">http://forums.matronics.com

 ======================       -Matt Dralle, List Admin.

 ================================



 



	




[b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jul 21, 2013 12:04 pm Post subject: jumpimg gauge needles

At 09:47 AM 7/21/2013, you wrote:

 	  Quote: 	
		  hi bob,

  ok, got the info. mitchell gauge for water temp., oil temp and oil 

 pressure. these 3 gauges all twitch, water temp. the worst. the 

 electric uma tach and the elec. vdo fuel gauge work fine. all 

 gauges have a separate ground wire back to a a common ground.


	


    Okay, a picture is beginning to emerge. I suspect

    those first three have single wires to the guages

    and they ground through their threaded fittings

    to the engine.



    My working theory is that there is substantial

    resistance between the crankcase and the "common

    ground." I.e. the common ground is NOT a forest-

    of-tabs on the firewall with a nice bond strap

    between crankcase and forest-of-tabs.



    The EASY fix is to take GAUGE grounds for the

    3 twitchy instruments out to the crankcase. I'm

    90% certain that the observed twitchiness will

    go away.



    Years ago I think I related a story about a Long-Ez

    driver who had a 30A alternator on the engine but

    no starter. His VERY long crankcase ground routed

    to battery(-) in the nose offered substantial

    voltage drop when the alternator was charging.

    This cause a rather large excursion in his gauges

    with local ground sensors when the alternator

    was turned ON and OFF.



    Bringing instrument grounds for those systems

    back to the crankcase DIDN'T change the voltage

    drop on the alternator ground wire, it just moved

    that drop OUTSIDE the signal loop for the gauge.



   Bob . . .

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