Homemade iPod
Cable Construction Unscrew the retainer
(pictured below - it's the part at the far right and has two flat
sides) The pin and fuse will then
fall out out and the spring might too Next, pop off the little
metal ring that is left with a small screw driver driver Now you can wiggle the first
part of the gray plastic case out (top most plastic piece in the
picture) Now you can pop out the
bottom gray plastic piece with wire harness and amplifier circuit board
from the white plastic bulb. Grasp the plastic bulb in one hand and push
up slightly on the gray plastic with the other hand. It should pop free
and pull out. Free the metal power and
ground contacts. These are the spring metal pieces in about the center
of the picture below. There is a little part of the
lower gray housing that acts as a retainer clip to hold the circuit
board in place. Hold this back with a small screw driver and wiggle the
circuit board free. Once you have the parts
wiggled free, you can snip the wires. Snip them as close to the circuit
board as possible to maintain the length. You will be left with the
harness still poking through the lower gray plastic housing. Since you
can't slide the harness back through, you need to snip away the gray
housing with a pair of side cutters until the cable is free. Throw everything away except
the cable (By the way, the circuit board is
nothing more than a cheap line level amplifier. Nothing is done to the
power signal ,it's "pass-through" according to Belkin tech
support.) This is how it will look once you have taken everything apart: And here's what you should have left over after cutting off the circuit board: Referring to the picture above and going from top to bottom,
here is the wiring breakdown: Thin Black
wire: Red wire: White wire: Medium Thickness Black
wire: Green wire: Yellow wire: Thick Black
wire: Just to be sure, I carefully
de-soldered it and measured the resistance using the Fluke meter. It is
exactly 1 mega-ohm, which matches what the code translates to. Measuring
the resistance while still in the circuit will give a false reading.
Make your audio connections
I used the Belkin Auto Kit for iPod for three
very important reasons:
Once you have the Belkin
connector, do the following:
This is one of three ground wires. It is the same type of a
wire as the white, red, green and yellow wires.
This is
power, +12VDC. I called Belkin tech support and they said that power is
just pass-through (the front line support guy was good enough to check
with engineering with little pressure from me). In other words, the
voltage can actually be anywhere between 11 volts (if you have a bad
battery and the car isn't running) and 14.5 volts (car running). The
iPod can apparently handle this variance, perhaps by way of a Zener
diode; only Apple knows. Anyway, just to be sure, I verified this with
my handy Fluke meter. It is indeed pass-through voltage from the
car.
Connect
this to one end of a 1/4 watt 1 mega-ohm resistor and connect the other
end of the resistor to ground. You can pick up a package of these
resistors at Radio Shack for about $1. Part number is 271-1356.
The other end of the resistor is the second of the three ground wires. I
didn't experiment much and do not know what purpose the white wire with
resistor to ground actually serves. I may experiment with this later or
call Belkin. Anyway, I'll update this page with the results.
This is actually the shielding around the green and yellow
wires, which are in a separate cable within the main cable. Anyway, this
is the common audio ground. Connect it to the negative audio signal but
not actually to the ground circuit. In other words, do NOT connect this
to the other three ground wires.
Left
audio signal
Right
audio signal
This is actually the braided shield for the main cable that
is just twisted together and inside some heat shrink. This is the third
of three ground wires.
This picture is a close-up of the
1 mega-ohm resistor that is on the Belkin circuit board. It is the little
black thing at the bottom labeled "01E." It is an SMD style resistor and
the code for it can be looked up here.
I used a Radio Shack 3 foot Y adapter audio cable, part number 42-2550.
Refer to the wiring breakdown above.
When looking at the Radio Shack cable,
remember your R's. Red = Right. Solder the yellow and green wires from the Belkin cable
to the corresponding inner cores on the radio shack cable. Gather all of the
shielding and twist it together. DO NOT LET THE SHIELDING COME INTO
CONTACT WITH THE AUDIO SIGNAL AT THE CORE. Gather each twisted cable shield from
both sides of the the Radio Shack cable and twist them together (to make one wire).
Then solder the shield from the Belkin cable to the 2 RCA ground wires you just
twisted together (top wire in the picture plus the two twisted wires at the right).
If the tiny wires inside your RCA cables look exactly like the ones pictured on the right, you can skip this blue paragraph:
(Depending on the brand of RCA cables you choose, there might
be 2 seperate tiny wires inside each RCA cable. Just remember that the red one is
always the right audio channel [positive], and the black ones will always be the
audio ground [negative]. If this is the wiring set up in your RCA cables, connect the right [red]
& left [other color] to the corresponding wires in your Belkin cable. Then wrap the 2
black wires from your RCA cables together [to make one wire] and connect them to the sheild from the Belkin cable [top wire in the picture plus the two black ground wires from your RCA cables].
The wires are thin and can be hard to see. This can be tedious for some so please have
patience. Though not pictured, be sure to ALWAYS use heat shrink tubing or electrical
tape to insulate the wires from each other after each connection you make.
Here you can see the bottom end of the resistor
connected to the white wire.
Notice how I connected the first black ground (thin) wire to the other end (the top end, but not the very top) of the resistor (It doesnt matter which side you choose to be the "top" or "bottom").
Also connect the outer shield (third of three
ground wires - the fat one pictured below between the resistor and the red wire) to
the top end of the resistor, but ABOVE where the thin black wire is already conntected. Then you will have to attach a new wire (not pictured) to the very top end of the resistor. This will be your main ground wire. The outer shield and black wire go
straight to your main ground wire. The white wire goes to the main ground via the
resistor.
The remaining red wire will be your main power wire. You'll have to attach a new wire to the end of this wire to extend it. I suggest that you add an inline fuse between the thin red Belkin wire & your new extended wire.
I chose this style of connector
to tap into power and ground of my cars, but you can choose any connector style that is easiest for you based on your type of car. When sliding the light blue
portion into the darker blue portion, be sure that the little "tongue"
slides in correctly. It's easy to push it out of the way and have NO
connection even though you pushed them together properly.
Here is my complete harness.
Notice how I doubled over the harness and wire tied them. I did this for
strength to take the load off of the tiny wires in the
Belkin harness that are very thin and can break easily.
Since I tapped into the audio
accessory wiring harnesses in the cars, which are already fused circuits,
I did not add another fuse. You can perform this optional step if you'd
like. You SHOULD DEFINITELY DO IT if you wire the iPod directly to an
unswitched power source such as directly to the battery or where the
circuit has no fuse. I suggest tapping into a "switched" power
source (meaning one where power is cut when the car is turned off) because when the power is switched off, the iPod goes into a paused
state.