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EXP2BUS and non-functioning alternator

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun May 17, 2009 6:33 pm Post subject: EXP2BUS and non-functioning alternator

At 05:08 PM 5/16/2009, you wrote:

 	  Quote: 	
		  



I discovered that the IG lead to the alternator was only producing 

12V when measured disconnected.  As soon as a load was applied that 

went down to 1.5V.   It turns out that some filings had got under 

the legs of an IRF4905 Mosfet and seemed to have shorted the pins.



So, new question:  Does anyone know how to test whether the cleaned 

up IRF4905 still works, and what the pinouts might be.  There are 

three legs, but nothing I've read tells me what leg does what.


	


   See:



http://www.irf.com/product-info/datasheets/data/irf4905s.pdf

 	  Quote: 	
		  Would I have to remove the IRF4905 from the board to test it's output?


	


   I wouldn't think so . . . but I'm mystified as to how

   an IRF4905 might be used to control an alternator. This

   is a really husky device. Far larger than necessary

   to effect control of the IG lead of an alternator. Do

   you have a schematic of the EXP2BUS product? I wasn't

   able to find anything useful on the website.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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ianxbrown

Joined: 16 May 2009
Posts: 80

Posted: Mon May 18, 2009 7:33 am Post subject: EXP2BUS and non-functioning alternator

Bob,

I have the installation manual (attached) but it doesn't have a

conventional circuit diagram.  There is a logical layout in Figure 7,

and a physical layout in Figure 3 (the IRF4905 is at J17) and a photo on

the front page, which also shows it's location.



There is evidence that the track leading from the Source pin on the

IRF4905 has overheated, but I have yet to check it for continuity (meter

is at the airport).



Ian



On Sun, 2009-05-17 at 21:31 -0500, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 

 At 05:08 PM 5/16/2009, you wrote:

 >

 >

 >I discovered that the IG lead to the alternator was only producing 

 >12V when measured disconnected.  As soon as a load was applied that 

 >went down to 1.5V.   It turns out that some filings had got under 

 >the legs of an IRF4905 Mosfet and seemed to have shorted the pins.

 >

 >So, new question:  Does anyone know how to test whether the cleaned 

 >up IRF4905 still works, and what the pinouts might be.  There are 

 >three legs, but nothing I've read tells me what leg does what.

 

    See:

 

 http://www.irf.com/product-info/datasheets/data/irf4905s.pdf

 

 

 >Would I have to remove the IRF4905 from the board to test it's output?

 

    I wouldn't think so . . . but I'm mystified as to how

    an IRF4905 might be used to control an alternator. This

    is a really husky device. Far larger than necessary

    to effect control of the IG lead of an alternator. Do

    you have a schematic of the EXP2BUS product? I wasn't

    able to find anything useful on the website.

 

 

         Bob . . .

 

         ----------------------------------------)

         ( . . .  a long habit of not thinking   )

         ( a thing wrong, gives it a superficial )

         ( appearance of being right . . .       )

         (                                       )

         (                  -Thomas Paine 1776-  )

         ----------------------------------------

- 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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