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Questions about the 9005 Low Voltage Module

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nuckolls.bob(at)aeroelect
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Posted: Sat Jan 01, 2011 9:56 pm Post subject: Questions about the 9005 Low Voltage Module

[quote]At 09:53 PM 1/1/2011, you wrote: Today it was cold and rainy so I had great fun soldering the various bits onto the 9005 PCB for the low voltage module in the comfort of the heated workshop.  When I got it all finished I made up a test lead out of a mating D-sub connector and two alligator clips.  Pins 4,5, and 9 all are connected to the red alligator clip, while pins 3,6,7,8 and the test LED cathode are all connected to the black alligator clip.  Pin 2 is connected to the test LED anode.  My plan was to hook those alligator clips to the truck battery, such that the LED would flash with the engine off and extinguish with the engine on, since the voltage situation would mirror the airplane that doesn't happen to have a functioning alternator yet.    Good plan . . .   I don't think it is working correctly yet, and I was wondering if Bob or anyone else who has built one of these might have some suggestions.  When I first apply the battery voltage with the truck engine off, the LED in the test harness and the LED on the PCB flash once, like Captain Ramius's "one ping only."    <snip>  Is it possible that a difference in current draw between this LED and the one originally supplied with the 9005 kits would cause this behavior?       No.  I should also add that I did not need the aux battery features so I omitted the three components Q114, R119, and Z118 as per the note in the documentation.     No problem.     With the device under test hooked to your battery    in a non-running vehicle.  Hook the minus lead    of your voltmeter hooked to battery (-). Measure    and record the voltages at the following test points:     U107  Pin 1     U107  Pin 2     U107  Pin 3     U107  Pin 4     U107  Pin 7     U107  Pin 8     Also     U110  Pin 1     U110  Pin 2     U110  Pin 3     U110  Pin 4     U110  Pin 5     U110  Pin 6     U110  Pin 8    

        Bob . . .                    ////                    (o o)     ===========o00o=(_)=o00o=========     < Go ahead, make my day . . .   >     < show me where I'm wrong.      >     =================================  [/b]    [quote][b]

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nuckolls.bob(at)aeroelect
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Posted: Mon Jan 03, 2011 6:36 am Post subject: Questions about the 9005 Low Voltage Module

At 07:57 AM 1/2/2011, you wrote:

  	  Quote: 	
		  Thanks Bob!  Here are the readings that I get.  Battery Voltage this morning is 12.3.



 U107  Pin 1: 0

 U107  Pin 2: 2.38

 U107  Pin 3: .68

 U107  Pin 4: 0

 U107  Pin 7: 11.24

 U107  Pin 8: 11.49



 U110  Pin 1: 0

 U110  Pin 2: 10.77

 U110  Pin 3: 0

 U110  Pin 4: 11.49

 U110  Pin 5: 7.66

 U110  Pin 6: 10.78

 U110  Pin 8: 11.49 	


   Okay, all of the voltages you've measured are expected

   values with one exception. Pin 3 of U107 voltage is

   established by the voltage reference Z103 and SHOULD

   be within 30 millivolts or so of 2.50 volts.



  http://www.national.com/ds/LM/LM185-2.5.pdf



   The fact that you're reading only .68 volts suggests

   that Z013 is installed wrong. See data sheet for pinout

   orientation . . .



 [img]cid:.0[/img]



    Note that the image is a BOTTOM view

    of the device. The pictures for assembly of

    the 9005 show the flat side of the device

    pointed toward the power transistor location.



    If you determine that the device IS

    installed wrong you should consider the

    best way to replace it. If you have the tools

    and experience to removed parts from a plated

    thru hole board, you have a high probability

    of re-using the original part.



    I very seldom pull a part off a board with

    any notion of reusing it. The value of the

    part is usually pretty small compared to the

    value of the whole. I usually clip the leads

    on the part to be removed so that they can

    be taken out of the holes one at a time thus

    minimizing hazard to the board.



 

 

   Bob . . .

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nuckolls.bob(at)aeroelect
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Posted: Tue Jan 04, 2011 7:14 am Post subject: Questions about the 9005 Low Voltage Module

At 09:28 PM 1/3/2011, you wrote:

  	  Quote: 	
		  That's great information, thank you for your help!  I found the Digikey invoice and I think I might have ordered the wrong part.

  

 The national part is the Digikey LM285Z-2.5-ND

  http://www.national.com/ds/LM/LM185-2.5.pdf

  

 The one that I ordered is made by ON Semiconductor, Digikey LM285Z-2.5GOS-ND.

  http://www.onsemi.com/pub_link/Collateral/LM285-D.PDF

  	


   I don't think so. The LM series devices are National

   Semiconductor originations. All competing manufacturers

   have to put out a drop in duplicate of the part.



   If the voltage at U107-3 had been zero or identical

   to an adjacent pin, then I would suspect a solder

   splash or an ECB defect often called a 'cat hair'.

   The fact that your measurement is unique and way out

   of whack for what the LM285 should present suggests

   that neither event is in force. You might check

   markings or color code for the R104 . . . make sure

   it.s a 4.7K and not something higher. Also re-flow

   the solder joins on R104. It's extremely rare that a

   new part is bad out of the box so if the LM285 is

   not installed wrong, we need to explore other possible

   causes for U107-3 voltage not to be 2.50 volts.



 

 

   Bob . . .    [quote][b]

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