Datasheet help - LX450 factory head unit AUX in wire

[bloc]

Hello all,

I'm in the middle of trying to copy what was done here to an S10 stereo: HOW-TO: AUX Port in your OE Delco Stereo! (Picture Heavy) - S-10 Forum

Short version is that they didn't need the tape deck in their head unit so they soldered a 3.5mm AUX input wire to the preamp for the tape deck.

I figured opening my Pioneer LX450 stereo would be easy enough to ID all of the relevant chips and figure out what to do.. but I was wrong.

I SUSPECT the chip I'm interested in is on the PCB closest to the cassette mechanism, and it appears to be a Hitachi HA12173. Link to datasheet, a block diagram is on page 7: HA12173 pdf, HA12173 description, HA12173 datasheets, HA12173 view ::: ALLDATASHEET :::

I found a FSM for the LX470 stereo KEX-9527M that narrows things down a lot, but they use a Hitachi HA12216F and the datasheets are different enough that I don't want to assume the pins all do the same things...
LX470 HU FSM http://www.clublexus.com/forums/att...-toyota_kex-m8527-kex-m8727_servicemanual.pdf
HA12216F datasheet: HA12216F pdf, HA12216F description, HA12216F datasheets, HA12216F view ::: ALLDATASHEET :::

The LX450 head unit is a KEX-P9066ZT. I haven't been able to find a good FSM for that yet.

Does anyone understand these things well enough to help me figure out where I should solder in an AUX adapter?

If I can figure this out the plan is to take detailed pictures and do a how-to in this sub. Didn't realize the datasheet stuff was so far over my head.

Thanks for any help.

 

[bloc]

Per the LX470 service manual it looks like the relevant wires would be pins 1 (gnd) 2 (R-channel) and 3 (L-channel) on the ribbon from the tape unit to the main PCB. Finding the same thing on a RX300 SM.

Under both it says
-8.24dBs(300mV)±1dB


After a little digging it seems .3v is common for an AUX input.. so should I take this to mean that is the correct spot for something like an AUX input?

 

[bloc]

Think I figured it out. Attached pic is the back of the main stereo PCB where the cassette module plugs in. sgtp, tpL and tpR appear to be the terminals I need. Now when the parts show up tomorrow I'll solder things up and see what happens.

Also considering getting a cassette and gutting the ribbon to keep the mechanism of the tape deck happy. I know some decks are set up in a way that if both spools aren't running it'll throw an error.. this is why most of the 3.5 to tape adapters have (noisy) gears and stuff inside them. I'll see what I can do about that.

 

[thatcabledude]

Nice work. A buddy of mine did this on his 08 Tacoma years back. Ties it into the CD player the same way. For it to work a cd had to be spinning inside.

 

[b16]

Why not just stick one of these in the tape deck? Its what I'm doing and works just fine, cheaper and a lot less work.

http://www.amazon.com/BESDATA-Universal-Cassette-Player-Adapter/dp/B00JAY397S/?tag=ihco-20

 

[canman]

Had one in for a few years now and it is finished. Not sure if head unit is damaged.

 

[bloc]

So after a little testing it appears that something will have to be in the tape deck spinning the reels or the deck will stop working. This means either keeping an old tape in there flipping back and forth, or stripping down a tape adapter so the gears & wheel inside can do the job. The good news is it is easy to totally disconnect the tape head so an old tape running won't play through the speakers at all.

Why not just stick one of these in the tape deck? Its what I'm doing and works just fine, cheaper and a lot less work.

Amazon.com: BESDATA Universal Car Cassette Player Adapter with 3.5mm Male Jack and 2.5mm Plug Adapter for iPod, iPad, iPhone, MP3, Mobil Device, Black: Cell Phones & Accessories

I already have one of those. Audio quality not as good, super-cheap build quality on the cable itself (and it matters because this thing will be getting used any time I'm in the truck), and I don't want the cable hanging out the front of the head unit.

Technically it isn't cheaper.. and the parts I am getting for slightly less money are higher quality and should last longer.

Plus, I tend to nerd out on stuff like this.

Now that I've had the head unit apart and figured out the terminals I think you'd be surprised how little work it actually is. Granted, I have more experience and confidence than most working on electronics.

Had one in for a few years now and it is finished. Not sure if head unit is damaged.

What is it doing?

 

[b16]

I guess my complaints of the sound quality exist from the head unit all the way to the speakers, aux cable quality is negligible.. lol

 

[bloc]

I mean more along the lines of physical quality. So much of these cheap phone charging cables and similar parts from china are total pieces of crap.

And.. after putting JBL speakers in all 4 doors I'm actually REALLY surprised at the sound quality out of this head unit and factory amp. The main reason for the speakers was the factory ones had literally fallen apart to the point that they weren't air-tight and allowed dust right through the door panel into the interior.

Either way.. I'll do the aux mod and post a how-to.

 

[canman]

Sound quality has deteriorated over time. I just recently purchased Pioneer rear door speakers as the OEMs have likely ripped. With the Pioneer front door speaker upgrade and the Tang Center speaker upgrade, I really was impressed with the sound quality from the OEM head unit/amp. I just now want to be able to play songs from my iPad using the head unit.

 

[bloc]

For anyone following this.. I got the cable soldered in and it works great. Chasing down some noise issues (only when the phone is plugged into the aux and no or low sound is playing.. when there is significant line level it sounds perfect) but think that is the aux cable I actually used. Yes, I realize that is ironic.

Either way.. gonna track down the noise issue then do a real writeup. Just wanted to update that it appears this will be a good option for people wanting to add an AUX in.

Still planning on messing with the top PCB from the changer.. but not in much of a hurry for that.

 

[bloc]

So it turns out the noise is a ground loop. I got a cheap ground-loop isolator on amazon and it totally fixed the popping and static issues at low volumes.. problem is it cut the overall volume down by about half. Even with my phone turned all the way up, the volume on the stereo needs to be about 3/4 up to have moderate-loud (loud enough to overcome wind and tire noise on the freeway).. compared to about half of this with the groud loop isolator removed.


It seems that with the cost of the aux cable + need to run some kind of casette with tape/reels in it + ground loop isolator + labor/soldering + potential wiring issues deviating from factory, the casette adapter is probably a better option.

I'm going to leave the aux cable in but unplugged, using my casette adapter for a while and see if it annoys me that much.

I'll probably still put a thread together showing the mods if anyone wants.. though at this point I'd suggest not bothering trying to hijack the tape input.

CD changer? again, unless you figure out how to hijack the comms between the changer and the head unit I don't see a cheap/easy way to make it work.

 

[canman]

I tried this...but had similar results regarding volume level and noise.

Adding Iphone to OE Stereo

 

[bloc]

I've practically memorized that thread.. don't have a working cd changer which seems necessary for the comms between the HU and changer to hijack that audio signal.

Thanks for the info though.

 

[b16]

Sound quality has deteriorated over time. I just recently purchased Pioneer rear door speakers as the OEMs have likely ripped. With the Pioneer front door speaker upgrade and the Tang Center speaker upgrade, I really was impressed with the sound quality from the OEM head unit/amp. I just now want to be able to play songs from my iPad using the head unit.

I've wanted to do exactly this. Which Pioneer door speakers did you use? And that Tang sub sounds good in there? Did you add any crossover to the sub?

 

[canman]

I've wanted to do exactly this. Which Pioneer door speakers did you use? And that Tang sub sounds good in there? Did you add any crossover to the sub?

"Tang Band W4-1720 4" Underhung Midbass Driver" from www.parts-express.com!

Yes, I like the Tang unit and believe the centre "sub-woofer" adds a lot to just the door speakers. Everything's is still stk except the front door speakers.
Just realized I had bought some rear speakers some time ago (TS-G1044R) . Picked up the TS-G1045R last week.

Also replaced my cassette adapter with a GE cheapo unit this morning. Had a Monster unit previously. Noticed a lot less motor noise with the GE adapter. Also cleaned out the head unit a bit with a Qtip as there is a lot of fine dust inside. Want to replace the rear speakers, but the black flies are brutal now.

 

[stevezero]

I hacked into the wiring harness on the cd changer under the center console, and soldered in two rca plugs (you cut the r +/- and l +/- on the harness that runs from the changer to the head unit. I dont recall the color code. I found the thread on clublexus forums. I connected the rca plugs up to a bluetooth adapter, added switched 12v power and ground. I dont use my cd changer anymore, and can stream audio from my phone with no issues. bought the bt adapter off ebay for 25 or 30 bux. You have to leave at least one disc in the changer for it to work properly. The volume level is only slightly lower than the radio level, and can be adjusted with the phone volume.

 

[lx470guy]

Hey guys I’m learning a lot here. But was wondering if someone could help out. I’m wanting to put a cheap Bluetooth adapter (has aux, usb, and receiver) on the circuit board of my tape deck. I have a 06 lx470 with the mark and Levinson.

I’m planning on soldering the L,R,and ground wires from aux cable and then wiring the usb to 12v ignition. Not sure where to solder for connecting aux.

Last picture is on the main radio board. Circled area is my best guess to where to attach

 

[KeenLexus]

Think I figured it out. Attached pic is the back of the main stereo PCB where the cassette module plugs in. sgtp, tpL and tpR appear to be the terminals I need. Now when the parts show up tomorrow I'll solder things up and see what happens.

View attachment 1252591

Also considering getting a cassette and gutting the ribbon to keep the mechanism of the tape deck happy. I know some decks are set up in a way that if both spools aren't running it'll throw an error.. this is why most of the 3.5 to tape adapters have (noisy) gears and stuff inside them. I'll see what I can do about that.

I know this is necroposting, but I just followed this advice with these results.

Soldered:
Ground to SGTP
Red to TPL
White to TPR

Result:
Aux in plays on ALL INPUTS, including Tape, CD and FM/AM

Solution:
My 6 disc changer works and I love it. In Disc 6 I have a blank CD-R disc. On vehicle Startup when CD Input is selected, and Disc 6 is checked, it will attempt to do so (makes some clicks) and then reads ERR 23.

That’s ok, cause immediately the Aux Input works as soon as you press play on your device! There is no grounding issues, and it’s clear as a bell.