On 11/24/2012 11:39 AM, Peter Field wrote:
> Does anybody know what retains the cables pushed into the terminal block
> (see photo)? The ignition circuit kill wires are the two white cables
> and we have had some trouble with these not making a good connection.
Apart from that they are not pushed fully home, as some others have
mentioned, I see a few more worrying things.
First, these wires should go to your ignition-switch and nowhere else.
But within a very short distance I see a screw terminal (which are
invented to connect lamp sockets to your house wiring - vibration free
-, but are totally unsuitable for car purposes, let alone aircraft
purposes), and some (soldered) connection within a shrink tube. Why is
there not just a straigth cable going to your ignition switch? This is
just asking for trouble, and it looks like your trouble already started.
The vast majority of electrical failures are due to bad connections, so
you should keep the amount of connections down to the absolute minimum,
and where unavoidable, use high quality connectors (and houshold screw
terminals do not in the least qualify for this).
Furthermore it looks like some bare metal wires are poking out of the
wires coming out of the screw terminal. I'm not sure what I'm seeing
here but if these metal wires are connected to the ignition wire, they
just have to touch anything and your ignition is killed.
To elaborate more on connectors: The problem with these screw terminals
is that they do not separate the electrical and mechanical connection.
An electrical connection (clamping) creates a stress point in the metal,
and any movement (vibration) focuses on this stress point using the rest
of the wire as a lever, quickly causing metal fatigue and unexpected and
unpredictable break of the wire. A good connector always has some way to
retain the wire upstream of the electrical connection, so that the
electrical connection point is absolutely free from any movement. (This
also applies to soldering: Any solder joint should be free from any
movement and vibration).
For connecting a lamp socket to your house wiring that screw terminal is
ok, because houses do not move or vibrate very often.
If you ever have a carb going bad and your engine starts to shake or
vibrate heavily, within a few minutes the wire will fall from the screw
terminal. When that happens, the wire will dangle down and if it touches
some metal it will kill the ignition.
Frans
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