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all right so we're going to talk about
testing an msd box for spark uh this is
a 6al inbox it's exactly the same as a
6al digital box that you would have in a
drag car a hot rod something like that
the only difference here is the back is
see-through and it's potted so you can't
mess with the internals
that way nascar knows that nobody's
cheated this box up to get some kind of
unfair advantage out of it so basically
what we've got going on here
we've wired it up the way msd tells you
to wire it
we've got our heavy red and our heavy
black are our main power and ground so
that's your 12 volt from your battery
and what we're supplying that with
is this power supply here which i can
adjust anywhere from 0 to 24 volts
and it goes up to 3 amps
but we're going to leave it set at 12
for this to simulate our automotive
battery
so
we're running this white wire
is what would run to your distributor
our colors don't correspond i use scrap
so bear with me on this uh i use the
yellow and we're going to use that uh
over here we're going to tap it to
ground and that's going to simulate our
distributor signal but the distributor
signal is what's going to tell this box
when to fire
so if we go to our six pin weather pack
here if we start at the violet wire the
violet and the green wires are for a
magnetic pickup such as a crank trigger
something you'd use on a drag car
you would use that instead of the
distributor signal you would never use
both together
so
we're going to carry that on i did have
violet and green wire in my scrap pile
so we kept that consistent our orange
and black wires here
i ended up using orange and pink so
don't get confused there but the orange
wire goes to the positive side of your
ignition coil
and the black wire which is our pink
will go to the negative side
here on this box our tack signal wire is
brown it's kind of hard to see because
it's an older wire so it's faded we use
blue for this test we're not going to
worry about that i left it over here
we're not messing with the tack right
now and then our last wire is our red
wire that is our 12 volt ignition source
so that's when you key on it's going to
supply a 12 volt ignition signal to this
box
so basically what we've got going on
here
is we've got a coil set up coil wire
coming from the coil and we've used a
bolt
in the plug to simulate a spark plug
we've got about a half inch gap here on
this ground we're using this uh this
piece of steel plate here as a ground so
what we're going to do is we're going to
do two tests to test for spark here i'm
going to do the distributor test first
and what i'll do is i'll take this wire
and tap it to my ground source and you
should see a spark jump across that gap
and it should be a pretty considerable
spark if the box works and then we'll do
our magnetic pickup test our crank
trigger test and all i'm going to do
here
is tap the purple and the green wire
together and that's going to do the
exact same thing you're going to see a
pretty massive spark jump across that so
here we go we're going to see what she
does
i'm just going to tap it right to the
ground
[Music]
so there we go we know our distributor
signal wire works
so that part of our box is operating
correctly we're going to do the same
thing here
we're going to tap the violet wire to
the green wire and it's going to
simulate the same thing so let's watch
our gap
so there you have it that's how you test
an msd 6al digital ignition box
