Building an AUX In with the stock CD-Player (now with pics!), See post 8 Options

[solidxsnake]

So I got sick of using a cassette adapter in my '95 Celica a while ago.. the mechanical noise of the deck as well as the tape hiss was incredibly annoying for a lot of my music.

I pulled the stereo out and checked pinouts on all the connectors online only to find there is no legitimate line-in source. I found L-R-GND pins in the 13-pin DIN socket on the back of the tape-deck head unit, but hooking wires up to it does nothing.

What I ended up doing was tapping into the line-in ports in the DIN connector by tapping into the CD-Player's line-out. This proved to be a headache at first, where what I did was tore up the CD-Player and pulled the corresponding wires from the 13-Pin DIN socket (LOut, ROut and GND) out from where they went into the CD-Player and connected to the logic board. What happened here was that, while it worked while the CD was already playing, it did not work if power was cut. When I turned the deck off and back on again, the CD player would not power up, as the headunit is expecting a specific line-in signal from the CD-Player (it's got a complex logic circuit)...

I had an epiphany yesterday, and went to work. I kept all of the wires connected to the board where they went, but instead removed some pins from the connector that connects the one logic board to the other (there are a total of 3 logic boards, the main one, the board that controls the optics/motors/mechanics, and the one with the buttons and LCD, that controls the faceplate and external interface). There is a small PCB Bridge between the main logic board and the optics board. I removed this PCB, then desoldered the pins L, R and GND from one of the connectors (you have two connectors to choose from, pick one). At this point, I soldered my L, R and GND from my AUX-In port (which I retrofitted in the faceplate, it can go anywhere really) to the main logic board. I hooked everything back up, and lo-and-behold it all worked great. Except for one small caveat, where if the optics had to pause to read the disc (for instance, a scratch in the disc, a bumpy road causing skipping, or seeking/skipping tracks), the sound from the AUX-In port would cut out. I found a wire inside labeled "MUTE."

The fix for this was to desolder one of the two pins on the bridge PCB between the main logic board and the optics board that connected the "MUTE" signal trace to both boards. And, luckily, it works flawlessly. Now I have a perfectly working AUX-In port in my stock CD player. All I need to do is press "CD" on my head unit (the CD unit, actually) and plug something into the AUX-In port I retrofitted, and I have a direct line-in into the head-unit. This MUTE wire, thus, is the wire that signals the head-unit to pause when the optical drive is either seeking the disc, or encounters a read-error.

The only problem with my method is that the CD-Player is left nonfunctional afterwards. What happens when the AUX-In is enabled is basically that the head-unit believes a CD is playing (and indeed, the CD is spinning in the CD-Drive, and the display shows a track and time, along with RPT, Scan, RAND, and other display icons), however, the audio signal it is sending isn't getting to the main logic board, and thus isn't making it to the tape-deck/head-unit, and thus isn't getting amplified or sent to the speakers. Instead, the line-level signal from the AUX-In port is sent to the tape-deck/head-unit, and is amped and sent to the speakers.

I feel as if that would be a simple fix, where you can integrate a switch on the CD-Player that controls a four-pole double-throw switch that connects the MUTE, L, R, and GND traces to their original position, or to the AUX-In port. A quick schematic would be:

CODE

To CD Player Logic-board "L" - Pole 1 Left Signal - To AUX-In port Tip/Left
To CD Player Logic-board "R" - Pole 2 Right Signal - To AUX-In port Ring/Right
To CD Player Logic-board "GND" - Pole 3 Ground - To AUX-In port Sleeve/GND
To CD Player Logic-board "MUTE" - Pole 4 Mute - Disconnected/Floating

With this schematic, you would have the stock CD Player functionality as long as the switch is flipped to the first set of throws (To CD Player Logic-board). To enable the AUX-In, start the CD Player as if you were going to play a CD, plug something into the AUX-In port, and then flip the switch, and voila, you have a line-in. Granted this is all theoretical, but I see absolutely no reason why it shouldn't work.

I'm not too worried about it as I managed to destroy the CD-Player mechanically (it doesn't eject or accept discs properly, but it will play them if I manage to work them into the drive and toy with the mechanics to lock it in and spin the disc). As long as I don't press eject, then I won't have to worry

I'll get up pics at some point. It's quite a bit of work for a measly AUX-In port, but it sure as hell beats spending money on a new head-unit for a free mod (or next to $10).

Any questions, please ask

This post has been edited by solidxsnake: Aug 14, 2009 - 9:10 PM

[SwissFerdi]

Wow that's a lot of work...kudos for being inventive though. But really, replacement single-DIN head units really aren't expensive, I'm sure you can get them for as low as $30.

[solidxsnake]

Lot of work to figure out, but it's only 3 wires and a little drilling/gluing (or even just running wires if you run a 1/8" stereo plug under the dash or wherever to where your mp3 player will be).

Free > $30

[SwissFerdi]

Free is indeed better, true. Pics of how you fit the AUX input?

[solidxsnake]

I'm not at home right now, but pics will come shortly. For a visual, it's under the "RAND" button on the bottom-left of the CD faceplate. I just picked up a random 1/8" jack and glued it into a hole I drilled.

[DanAdamKOF]

Dude, thanks for posting this. I was toying with a few ideas as to how to add an Aux In to my factory headunit (I like the stock look, at least for now...), and it seems you've taken care of everything.

Now all I'd have to do is figure out where the appropriate points are on my CD Player headunit (seems like yours is different), and figure out where to mount everything... I was thinking of mounting them inside that under-the-radio compartment, but I'd have to reach all the way in there to mess with them. Maybe I'd mount them on the lid, right underneath the headunit... Well, I guess that's all up to me.

[solidxsnake]

Dude, thanks for posting this. I was toying with a few ideas as to how to add an Aux In to my factory headunit (I like the stock look, at least for now...), and it seems you've taken care of everything.

Now all I'd have to do is figure out where the appropriate points are on my CD Player headunit (seems like yours is different), and figure out where to mount everything... I was thinking of mounting them inside that under-the-radio compartment, but I'd have to reach all the way in there to mess with them. Maybe I'd mount them on the lid, right underneath the headunit... Well, I guess that's all up to me.

You want pictures? I forgot to take them, i'll go snap some now if you'd like

BTW, What under-the-radio compartment? I'm not sure about your car, but my stereo system consists of the head-unit (tape-deck and AM/FM Radio) and the CD Player. The tape-deck is a single-DIN unit, the CD-Player another single-DIN unit. When you say "under-the-radio" compartment, I feel as if you may be referring to the single-DIN pocket that comes in Celicas without the CD-Player. If so, I'm not sure what I did would work

Though the fact that you have a CD-Player disproves that... unless at some point Toyota incorporated a single-DIN head-unit with a CD-Player that I'm not aware of (a very likely possibility).

This post has been edited by solidxsnake: Aug 14, 2009 - 7:10 PM

[solidxsnake]

Pictures up!

http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1079.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1080.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1082.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1083.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1086.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1087.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1089.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1091.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1092.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1093.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1094.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1096.jpg
http://bostonrinkrats.bostonrinkrats.com/s...in/IMG_1097.jpg


This post has been edited by solidxsnake: Aug 14, 2009 - 9:09 PM

[DanAdamKOF]

Hmmmm that's kinda different

Here's mine: http://i17.photobucket.com/albums/b72/DanA...OF/DSCF3119.jpg

In theory it would work about the same, all CD players would have the same analog audio + mute signals somewhere in them. Disabling the mute is key so that whey your disc is rewinding, etc. you don't get a pause.

But I'd imagine everything is integrated into my headunit pretty tightly, and wouldn't have much of a place to intercept the signals (I don't see why it would need a sub-board).

The signals still have to exist somewhere, and here's where it gets kinda tricky... but I could (intentionally) break the traces for the signals leading from the CD player, and use either side of the break as solder points, to solder to a 3.5mm jack and a switch. That sounds beyond my capabilities though.

I guess I'll have to pull my CD player apart sometime and poke around. I haven't actually done that yet.

I saw this recently, which led me to search and find your post: http://www.instructables.com/id/MP3-player...for-car-stereo/
and then it led me to this: http://www.instructables.com/id/Corolla-20...aux-input-hack/
if this upside-down method works for opening up the audio input, this could be an acceptable substitute.

This post has been edited by DanAdamKOF: Aug 14, 2009 - 9:23 PM

[solidxsnake]

EEEEEEeeeeehhh... that's just a bit different. Yeah, the concepts should be the same, and even better would be that you wouldn't have to worry about having to deal with the digital interface between the tape-deck and CD-Player (that uses the 13-pin DIN Connector, that you can see in the second pic I posted above). All you'd need to do is intercept the signal.

If you can post up pictures of the inside of your player, I'd be glad to help you out. In fact... now that I think of it, your car has amplifiers, doesn't it? My car ('95 ST) has the 4-speaker audio system, without any external amps. Do any of your amps have a line-in? Check the pinouts for that head-unit if you can find them and see if any of the pinouts are L, R or GND. My tape-deck doesn't have pinouts like that, it has ­±Front Left, ±Front Right, ±Rear Left and ±Rear Right (8 separate wires). The tape-deck doubles as an amp, which is why it has direct speaker outs, as well as no line-ins. If your car has external amps, some of the wires going from the head-unit to the amp should be a line-level connection between the two.

[DanAdamKOF]

I don't know if I have an amp, I guess I need to pull my center console out to check. It's an option I've considered, but it has a few problems. Namely, I can't adjust the volume, bass, treble, etc from anything except my device. If I use an iPod with line-level audio, for example, I can't adjust its volume. My solution would be to use a 3 position switch to toggle between headunit, mute (N/C), and line-in going to the amp, and a potentiometer that can adjust two signals at once (L and R of course) between the switch and line-in jack (or now that I think about it, a simple two position toggle, with one being the headunit and one being the line-in, and turning off the headunit to mute, would work better). I do kinda hate that I can't really adjust the sound any further though, it's hard to get a good bass sound out of my setup without having the headunit boost it a bit, and especially because my two 8" door speakers aren't putting out any sound (probably have a loose/severed wire somewhere).

I'm just glad to see someone on here that would rather make do with what they already have in tweaking their sound system, than just buying a new one. It's cheaper and funner to DIY.

[solidxsnake]

I don't know if I have an amp, I guess I need to pull my center console out to check. It's an option I've considered, but it has a few problems. Namely, I can't adjust the volume, bass, treble, etc from anything except my device. If I use an iPod with line-level audio, for example, I can't adjust its volume. My solution would be to use a 3 position switch to toggle between headunit, mute (N/C), and line-in going to the amp, and a potentiometer that can adjust two signals at once (L and R of course) between the switch and line-in jack (or now that I think about it, a simple two position toggle, with one being the headunit and one being the line-in, and turning off the headunit to mute, would work better). I do kinda hate that I can't really adjust the sound any further though, it's hard to get a good bass sound out of my setup without having the headunit boost it a bit, and especially because my two 8" door speakers aren't putting out any sound (probably have a loose/severed wire somewhere).

I'm just glad to see someone on here that would rather make do with what they already have in tweaking their sound system, than just buying a new one. It's cheaper and funner to DIY.

Completely forgot that the only volume/EQ settings are on the head-unit =_=

Yeah, you will have to find a preamp-in, huh? That's pretty key.

I DIY damn near everything I own. Everything I have has a personal touch, much of which is improper or incredibly ghetto. For instance, my computer (by far my biggest hobby, also my biggest expertise, along with electronics) is watercooled... the parts are all proper watercooling parts, however the reservoir is held to the case with rubber bands and the radiator is just sitting on the floor of the case without any bolts or retaining at all, if I tilt the case the wrong way it'll crush all the parts in my comp

In the process of changing the stock stereo's SMT LEDs to red. I ran out of LEDs, so I'm probably just gonna pull the lights from most of the buttons (FF, Rewind, Rand, Scan, CD eject, Rpt, etc) and only light the ones that are useful (AM/FM, Tape, tape Eject, CD, Power/Fade/Bal, bass/treb). It looks AWESOME, but I gotta figure out what to do with the LCD backlighting (might even just pull the backlighting for the CD LCD, it's useless anyhow).

This post has been edited by solidxsnake: Aug 15, 2009 - 11:18 AM