Looking to use iPod, no manual to tell how to switch to the addaptor
You definitely can wire an auxiliary input into a pioneer DEH-1400. The
design of this unit is highly modular and thanks to the engineers who
designed it there is an easy, straightforward way to add an aux input
to the unit. The way to do it is to decouple the the AM/FM receiver
stage from the volume control/Amplifier stage and inject your MP3 audio
signal there. If you have experience taking things apart, know how to
use a soldering iron and are good at basic electronic wiring you can do
it. It does take some time but for me, it was worth it.
Look for and down load the service manual for the deh-1400. I saw it on
a number of sites and at least one of them lets you D/L for free. This
has a schematic and will help you understand everything described here.
There are spare (unused) line level audio inputs to the Volume
control (VC) chip but I was concerned that I would have to somehow
re-program or spoof the system controller to tell the VC chip that the
spare is being used, so instead I just decoupled the AM/FM receiver
line stage from the VC chip. This is easily done by desoldering and
removing jumpers JP96 and JP100 from the circuit board. You will see
the jumpers when you take the unit apart, they aren't shown on the
schematic or labled on the PWB layout drawing. These jumpers connect
the FM line out to the input side to C311 and C312. Once the jumpers
are removed, you now have a usable stereo line level input to the VC
chip that utilizes all of the audio equalization and amplification
features of the unit.
So how do you select between AM/FM
source and Aux. input source you ask? Well, I just took the brute force
approach and wired in miniature Double Pole, Double Throw (DPDT)
Switch. One position joins the FM stage to the VC chip (like the
jumpers previously did) and the other position connects the Aux. input
to the VC chip. A convenient space near the head unit (on my 15 year
old truck) was available on my dash to mount the switch and 3.5 mm
stereo input jack. (sweet).
Another way to do it is to use a
3.5mm input jack that has normally closed connections which open when
the plug is inserted the Aux. jack (like GC electronics part number
30-574). (this saves a second hole in the dash and a switch that you
have to flip).
I used twisted, shielded pair wiring for all wiring, (shield used for
audio ground) I enlarged an existing hole on the back of the sound deck
(between the heat sink and the line out jacks) to run the wiring out. I
picked up audio ground at the ground jumper for the VC chip (were C307
and C309 are connected in common). The solution sounds great and works
good. Just run the radio in FM mode, plug in your MP3 to the Aux. Jack
and ignore the tuning display. (or tell yourself "wow, every station is
getting music I like ... and commercial free too!)
Notes on Input volume level setting and input impedance: If you are
plugging your mp3 player directly into the Aux. jack you will probably
notice that you should adjust the volume level on the mp3 player in
order to match the volume level that is fed from the AM/FM receiver to
avoid a sudden change in volume level when switching between sources.
If you are getting fancy (like I did) and putting a docking station
into your vehicle or you just don't want someone plugging in their mp3
player at max volume and making you have to then turn the radio volume
down, you should put an attenuator circuit in line with the Aux. input.
The attenuator circuit that I used is a simple home made (dual for
Left/Right) resistor divider network. I used the same resistor values
that pioneer used in their design coming out of the AM/FM receiver
stage. (2.7K Ohm for the series elements, 1.6K Ohm for the shunt
elements) I used 1/4 W, 2% metal film resistors. This will provide
approx. 4.3dB of attenuation and should match the line level out of
your MP3 (or the earbud out at max volume setting) to the volume level
sent out by the FM stage thus allowing smoother volume transition when
you plug the MP3 player in. The resistors also provide some
isolation/matching between the (relatively) low impedance of your MP3
output and the VC chip. (The attenuator is really optional but I like
having the volume levels matched when I move between sources).
Good Luck, worked for me.
Aug 16, 2008 |
Pioneer DEH-1400 CD Player