w00t! hacking Pioneer DEH-345 HU easy?

Telek · 11-11-2002, 06:05 PM

Hey guys, kickass. I just took apart my Pioneer DEH-345 head unit and guess what! not only is it nicely modularized (the radio unit is on it's own riser, and the CD unit is entirely removable and connected to the main PCB via a ribbon cable), but the main PCB is also labelled... Strange, eh? Every pin for all of the connectors has a label on it... So I figure that the CD connector will be the best one to hack into to get a line-in feed (because I can just feed in a blank CD so that there's no other line noise and I don't fsck up the radio input)...

So here's what I have for the CD connector pinout:

Code:

                 (01) VD
(02) DINC        (03) EJTD
(04) CLAMP       (05) XRST
(06) XAO         (07) XSTB
(08) XSI         (09) XS0
(10) XDSCK       (11) FOK
(12) MIRR        (13) LOCK
(14) CONT        (15) CDR0
(16) AGND        (17) CDL0
(18) CD5V        (19) CDLOAD
(20) CDEJET      (21) CDGND
(22) CDGND       (23) PGND
(24) PGND        (25) PGND

so, by the looks of it I should just be able to use pinsets (15,21) and (17,21) for the R,L channel line-inputs, yes? Anyone have any experience with head unit hacking? This is kinda neat, because this HU has a tuner like 100x better than the alpine unit that I have in the car right now. And I should just be able to play a blank CD (or maybe even just have no CD in there, I don't know if that would work) and then pipe in my own line-level input, right? Is there any precautions that I should take or things that I should take into consideration. I can use my SB-Live's lineout to make sure that I get a stable line-level output (I think).

Thanks for your input!

Telek · 11-12-2002, 08:13 AM

Yahoo!! IT worked fine... The output from the CD-unit went into 2 2.188Kohm resistors (dunno why, it just lowered the volume of the output from the CD unit) so I just unsoldered those resistors, put in some cat5 wire and connected it to an old turbo-switch (switch allows an A-B or B-C connection, A,B,C are pairs of wires), and then connected the 'C' connection on the turbo switch to an extra set of RCA female jacks, and presto, I now have an aux-input! The HU still has to be in "cd player" mode, but all I have to do is push in the switch and it now takes the line-level input from the new RCA jacks instead of the CD-player. Push the switch again and it's back to the CD-player (I did this so I wouldn't accidentally screw up and pipe in both inputs at the same time, and because the CD player has to be "playing" at the time for the input to work at all).

(Oh yeah, when I said "labelled" I didn't mean just like R1 and C02 and stuff like that, it has a lot of labels like what I copied down for the CD connector, and it has them for the radio, both of the connectors, and in multiple places all over the bottom of the PCB)

Here are some pretty crappy pictures, unfortunately I only had my webcam to take pictures with.

Here you can see the whole main PCB, the black connector front left is for the faceplace, the white connector upper left is the main connector for power/speakers. The white connector offcenter is the CD unit ribbon connector cable. To the left of that is where to 2 resistors came out from the bottom (top is CDL0, bottom is CDR0), and to the right is the CDGND connection. I used hot-melt glue to hold everything in place after I soldered it just so that it won't move and break later on.

This is a slightly better picture of the connections

Here is where the cables come out of the bottom of the unit.

Here's the turbo switch connector I was talking about.

Here's the CD-unit (disconnected) with the ribbon cable.

I'm really curious now to see if I can somehow hack into the signal cables and perhaps use the CD-controls to actually control the computer media playback... that would be really sweet :P

Hope that this might help someone.

Charliey · 11-12-2002, 04:55 PM

Thats really interesting. Looks like youve got one of the easier to mod headunits out there.

jol · 11-13-2002, 04:12 AM

Nice pioneer-ing there

meabye others get the courage to open up their hu's too now

Telek · 11-13-2002, 05:00 AM

yeah! even if you don't know which pins are which, it should be easy to brute force it... Switch your voltmeter to AC and look for a few pins on the connector to your CD unit that are tied together (this will most likely be ground). then check the AC voltage between that and different pins and once you find one that varies around 250mV, that's most likely audio. grab a pair of headphones or a speaker and carefully connect those pins to the speaker, and if you hear sound then you're in business!

If your amp has a pre-out as well, you can trace the lines from the connector to the preout. There's only a few components in the path between my 2 pins for audio and the pre-out, so that's another method to find it.

Another method to find the CDGND is to also look for continuity between the outside shell of the pre-out connections and the different pins in the CD connector, the ones that have a connection are most likely AUDIO GROUND.

Good luck everyone! Just remember, as long as you're careful and remember how to put it back together, using a voltmeter isn't very dangerous... just make sure that you don't cross any pins by mistake (i.e. touch 2 pins at once). Grab a magnifying glass and make sure that you have a steady hand and some good light. Even if you cross some pins by mistake, as long as they're not voltage carrying pins you're most likely OK. I accidentally touched 2 pins together and just had to turn the unit on and off and it worked again.