Date:         Sun, 17 Aug 2008 06:00:40 -0700
Reply-To:     mdrillock <mdrillock@COX.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mdrillock <mdrillock@COX.NET>
Subject:      Re: Dometic Wiring Question
Comments: To: RAlanen@AOL.COM
In-Reply-To:  <ccb.328dd406.35d96a7b@aol.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Frank, the power comes from the thermocouple itself. That is the "magic"
of the thermocouple. It makes a small voltage from the heat and that
voltage goes over the black wire to the LED panel where it is amplified
electronically to a stronger signal that can turn on the flame LED.

David did not make his correction of my post as clear as he could have.
What he said was that the voltage from the "magic" thermocouple is
negative with respect to ground, not positive as I said.  The voltage
still comes from the thermocouple. The black wire is NOT for a ground,
it carries a voltage to the LED panel, though according to David a
negative voltage.

You can see this for yourself if you have an early Dometic with the
small electric meter for the flame. The flame  meter works with no
external electrical power connected to the fridge whatsoever. The real
purpose of the thermocouple is to provide voltage to the safety valve.
This voltage is used to hold the valve open when the flame is lit. If
the flame should go out, the heat stops and the thermocouple stops
making the small voltage and the valve turns off. That is why it is
called the safety valve. It turns the gas off for safety if the flame
should go out. The valve has a small electromagnet in it. The button you
push during lighting opens the valve but once you take you finger off
the electricity from the thermocouple is what keeps it open if the flame
is on. That is why you have to hold the button for a short while after
lighting. Once the flame heats up the thermocouple enough it makes
voltage to hold the electro valve open after you let go. The flame meter
and flame LED merely provide a way for us to see that the voltage is
being generated by the thermocouple so we know we can let go of the button.

Mark



Frank Condelli wrote:
> In a message dated 16/08/2008 12:26:59 P.M. Central Standard Time,
> LISTSERV@GERRY.VANAGON.COM writes:
>
>         Mark, if that's true where  does the positive power come from to go
> up that black wire.  That spade  terminal on the back of the safety push button
> switch has no power going in so  no power can be going out through that
> terminal. ???????
>
>
>
>
>>>>>>> This positive lead is later used
>>>>>>>
> for the  flame LED though many times here people have wrongly referred to
> it as a  ground. Frank Condelli's Dometic writeup perpetrates this error.
> It is not  a ground at all, but a positive voltage source for the LED
> flame  indicator.<<<<<<<
>
>
>
>
>
> Cheers,
>
> Frank  Condelli
> Almonte, Ontario, Canada
> '87 Westy & Lionel Trains (_Collection for sale_
> (http://members.aol.com/Fkc43/trainsal.htm) )
> _Frank Condelli &  Associates_ (http://members.aol.com/Fkc43/busindex.html)
> - Vanagon/Vanagon Westfalia Service in the Ottawa Valley
> _Vanagon Stainless Steel Exhaust  Systems_
> (http://members.aol.com/Fkc43/exhaust.htm)
> _BusFusion_ (http://members.aol.com/BusFusion/bfhome.htm)  a VW Camper
> camping event, Almonte, ON, June 12 ~ 15,  2008
>
>
>