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GNS430 Communication Voltage- 14v or 28v?

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nuckolls.bob(at)aeroelect
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Posted: Mon Apr 18, 2011 1:31 pm Post subject: GNS430 Communication Voltage- 14v or 28v?

At 02:26 PM 4/18/2011, you wrote:

 	  Quote: 	
		  I found the source that I was talking about earlier.  It's on page 

H-12 of the 430W manual that Bob has on his site.  The note says "If 

the aircraft has multiple power buses, it is recommended that all 

GNS 430W power inputs be connected to the same bus."  I wonder why 

they would suggest that?


	


   Because the multiple power inputs are not designed be

   either/or . . . all inputs are necessary for full up

   operation of the system. Therefore it is not recommended

   that one input come from say the main bus and another

   input come from the e-bus.



   If your design goals call for this system to be

   available in the endurance mode, then all power inputs

   to the system would come from the e-bus . . . which

   is also the most failure tolerant bus having up to

   three sources of power through two independent pathways.



 	  Quote: 	
		     Has anyone else separated the two inputs over a main bus and an 

 AEC E-bus and had good results?


	


   How would one guage "good results". Without going through

   a proof of concept study for abnormal operations, a system

   that was split between busses having different levels

   of accessibility would go un-explored.

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 18, 2011 6:27 pm Post subject: GNS430 Communication Voltage- 14v or 28v?

 	  Quote: 	
		  I believe it is Bob? at TCW that sells the power conditioner/backup 

supply unit. He told me that is how it is suppose to work. If you 

look at his website he has a schematic that shows the two power 

busses hooked up to different pins in the 430.

See:

http://tcwtech.com/Installation%20instructions%20model%20IBBS-rev1.9.pdf

Tim


	


  But that's not a Garmin schematic designed to support their

  product in architectures vetted by their engineering staff.

  This schematic is about applying a 12v standby battery to

  various combinations of ship's accessories. Design goals

  for AEC architectures is to provide failure tolerant (meaning

  reliable power sources) that do not benefit from adding on

  band-aid batteries.



  Without a good knowledge of TCW's design goals and

  the rational for their recommendations, I'm  unable

  to offer a judgement as to potential for error or

  reduced reliability.



  In any case, you can't go wrong taking Garmin's advice

  for installation of their products.

   Bob . . .

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rnewman(at)tcwtech.com
Guest

Posted: Tue Apr 19, 2011 4:05 am Post subject: GNS430 Communication Voltage- 14v or 28v?

Regarding the recommendations for wiring found in the TCW  IBBS install 

manual:



Although the wiring diagrams are found in a TCW publication they were in 

fact "vetted" by Garmin.   We worked very closely with Garmin in developing 

our IBBS and IPS series of products and they tested samples of each before 

we went forward with publishing our install manual.     Although you will 

never find Garmin directly endorsing any third party products,   you will 

find that these TCW products have been written into the Garmin Installation 

Manuals for the Garmin G3x and G900x products.



Perhaps I can clear up the "powered from a single bus " question that Tim 

referred to for the 430W manual, (however I don't work for Garmin,  I just 

worked "with them" on related product developments ).      I believe the 

single bus statement is meant at a high level,  meaning powering the whole 

unit for normal operation.   The 430W/530W units effectively have 3 

significant power inputs, (ignoring the super flags). These inputs power the 

GPS/Nav portion of the unit and Comm portion of the unit.    Two inputs 

called Aircraft Power1 and Aircraft Power 2 are dioded ORed together to 

power the GPS/Nav portion of the product.   Comm Power only powers the radio 

section,  however,  powering the Comm section alone doesn't make the pretty 

screen with useful display info work,  so to be useful the Comm power and 

GPS/Nav power must be present at the same time if you want to use the radio. 

Hence from a high level the single bus comment.   Now the 430 or 530 box 

will work in the GPS/Nav only mode with the radio off line,   this is done 

by just powering Aircraft Power 1 or Aircraft Power 2 inputs as shown in our 

manual or in the G900x manual   (remember, the G900x has a sub-unit called 

the GIA63W which effectively is a faceless GNS530w box, in this manual you 

will find a TCW IPS-12v-8a providing power conditioning to the Aircraft 

Power 2 terminal of the GIA unit and their display unit GDU1040).



Now regarding the multiple pins for each of these three inputs on the Garmin 

unit,    I was told these were for redundancy and current handling 

capability, particularly on the Comm power input which has a higher peak 

current requirement than the GPS/nav power input/       So for example,  the 

Aircraft Power 2 input on a GNS-430W is provided on P4001, pins 15 and 72. 

These pins are literally tied together on the circuit board to form a 

redundant pair of connections,  typically the wiring harness maker will 

connect his single feed to this "input" right at the connector body, 

splicing the feed wire into two pins that feed the respective input.

Hope this helps,



Bob Newman

TCW Technologies, LLC.



---

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