Date:         Wed, 28 Aug 2002 09:56:22 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Indicator light (fridge propane)
Comments: To: Todd Last <Rubatoguy@MINDSPRING.COM>
In-Reply-To:  <3D6C82B7.2010907@mindspring.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 03:58 AM 8/28/2002, Todd Last wrote:
>I'm not sure if this is a failure of the  water  tank sender unit, or if
>the Blue LED has a much lower forward voltage requirement from the ones
>fro mthe factory,.

Actually it's much higher -- but there's plenty of drive voltage so you
don't notice.

You might check the board for solder bridges or poor solder
joints.   Beyond that (if you care) you're going to have to go through it
carefully with a sensitive voltmeter or scope to see what's actually
happening.  The flame detector light should come on when its input goes
some few millivolts *negative* to board ground.  There's nothing in the
water level circuit that should trigger it, but it's a very sensitive
circuit with a design gain of almost 400.  Schematics are on my website,
see below.  The flame detector amp is the first amp in the right-hand chip
(the other three are for the voltage LEDs).

david


--
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"