Aux cable to factory tape deck

Check both sides of all the circuit boards in your deck. It should be labeled something like R-OUT, L-OUT, S-GND

 

My original 1998 single din radio with the cassette player and pocket underneath had an extra unused plug adjacent to the speaker/power harness IIRC. If I'm not wrong that would be for the CD changer. My radio had the CD button so the CD changer was an option instead of the pocket.

They're apparently super rare, I've never seen a Taco with one installed. Everyone either has the double din full radio or the single din with the pocket.

 

What is the numbers on the square IC chip?

 

I think my radio is diffferent but I just took it apart and on the top daughter board adjacent to the cassette player assembly there is a SONY IC labeled IC1. It's super hard to read but from what I can make out it appears to say "SONY A1 9800" and then there appears to be a Dolby stereo logo and the numbers "735, 785, or 795" but I can't tell the middle number since it's so small. Below that is "G87K" The "G" could be something else but it's hard to tell.

 

Maybe the OP can give me better numbers. Cant find that chip with that info.

 

I think the cheap china part from ebay was the problem, not the fm modulator part. A decent one will sound no worse than a regular radio station. A $2 from China, I wouldn't expect much else than bad sound. No plug in option is going to sound better than the port it's plugged into is capable of delivering, headphone jacks aren't usually studio quality sound.

I used a jabra cruiser (cruzr? maybe) for years on varying vehicles until I would get around and install a BT capable headunit and then it would go into the closet. And then I'd change vehicles and out it would come again. It worked well until last year when it failed completely in my wife's car. BMW, not the most swapable stereo vehicle made to put it lightly. So replaced it with a new one and she's back in business.

 

OK so mixed bag fellas. I met most of my original goals: I can play from phone/mp3, I spent nothing (scavenging parts), little or no change to stock look (drilled a hole where the 3.5mm port fits cleanly in the expansion spacer just above the radio, pics forthcoming for vasinvictor). However, sound is clear but not clean, requires some volume adjustments on radio and mp3 to get right (more on this later).

First, here's what I did:

I wound up soldering L audio to one pot and R audio to another. Red squares show each pots 3 connections, black circles are the connections I made. Ground was made on a ground screw elsewhere.



The sound: there's a perpetual background noise, a hum or vibrating sound. It's constant but can only be heard when I pause the music, and doesn't rev with the motor like a bad ground. I know almost nothing about electronics but here's some observations and my best-guesses: It could be my scavenged parts or even my connector cable. I'll start by replacing the cable, and trying a different "blank tape".

Its also possible that the Sony chip in the pic above is meant to process sound from a tape deck, but the sound I'm feeding in is already clean/processed/amplified. If I'm tapping into the PCB before the chip, and I think I am, it could be trying to amplify or clean up a feed that doesn't need it. The pots could also need some adjusting, as they're factory set to a certain level, presumably for audio from a tape deck. I'll try and adjust this if a new cable doesn't give better results. I think the over-processing or amplification could be the issue because the speakers pop when I plug in or remove the jack - if the volume is high enough - and appear to "kick" the male 3.5 plug out when I remove it (this "kicking" could be in my head).

Other options: Per BartMan's suggestion above, there is an empty port in the back of the radio for a CD player expansion. If I can find a manual for this, it might be easier to hook up here. The signal processing would be close to the sound quality for a CD as for a digital file, and I wouldnt have to sacrifice my tape deck or use a blank tape or CD if I do it right because there's a CD button on my radio that currently does nothing. Only trick is to find out how to fool the control unit into thinking there's a cd player to kick over to.

NOTES FOR FUTURE MODDERS: I didn't mess with the CD input because I already had it all apart, didn't have the wiring diagram for that factory plug, and already had my mind set on soldering something to the PCB (don't judge me, you know you've been here before). For future reference, users may want to start with exploring that CD input slot. It might save a whole lot of trouble. Eventually, I'll get irritated with the noise if adjusting the pots doesn't work, and explore the CD input. If I can't find a wiring diagram for the input, is there a way to ID the prongs with a multimeter? I need to find L and R audio input prongs and I'd assume there'd be some wiring from the PCB to "activate" the CD button on the board.

 

The back ground noise your getting is from the preamp IC. Read the link I posted above. tells how to get ride of all the noise.

 

this one.

 

Check the FSM. The CD changer was a rare add-on, but it was still Toyota OEM.

 

I thought about looking into the CD jack myself but I don't think it will work. Assuming the output from the CD player is just information and not 'sound' as such, I think you would be at best accomplishing nothing. The radio is looking for a bunch of 1's and 0's that it can assemble into sound. Anything you pull from a headphone jack is a high level output.

 

I figured you'd say that, and I figured that's what it was. That write-up left something to be desired, but should prove helpful. The FSM I have only includes body electronics and the pdf below is the closest I can find to a detailed manual, though its for the tape/cd combo Not my model, despite some similarities in architecture.

If Im reading it right, both tape and FM radio are fed through the same amp. I dont know that's the case with my model, though I don't know its not the case either. I dont want to lose my radio. This give any help mechanicjohn? I'll pull the unit tonight and get the serial off that Sony IC...that'll probably be more help than anything.

http://reboots.g-cipher.net/panasonic_cq-jt1010x_cq-js6910x_toyota.pdf

 

OK, good news. Just like mechanicjohn said, and per the instructable he sent, I figured it out. I was leery because that instructable wasnt model specific and calls for removal of an IC. So, like it says, trace the tape head input on the main board to the pre-amp. I tried disabling it, by cutting trace to power, and eventually convinced myself it was the culprit and ripped it off there. I used the schematics from the above pdf. Here's the part I was looking for. on the right is input from tape ribbon.



The Green line on pins 16 and 6 are what I was after. I cut the trace on pin 5, but still had feedback. Desolder or cut it off carefully (For me, this chip was SONY 25650, but regardless of the chip, follow the traces from the tape ribbon to this tape pre-amp to find yours.) I could not find specific schematics on my stereo, but luckily the above was close enough for jazz (or electrical engineering in this case).

After that, follow the traces for L and R audio OUT to their nearest solder points and solder down your audio. Simple as that. Be careful because those solder points don't provide a ton of space to work with. Sound is clean N clear.


Blue boxes were my final solder points for R and L audio.

 

Lineout was the 2 you were looking for and used?

 

What is that IC responsible for? W

What is that IC responsible for? How does disabling it fix the audio issue?

Does the tape deck still work with this mod?

 

The tape signal from pickup head os very week. The IC boosts it to a stronger signal. That matches what a CD player puts out. It's alwsys on and will cause line noise. It will disable tape deck. Using a cassete is pretty ooooold school.

 

Darn I kind of liked the tape deck. I took my stock radio out and put in a touchscreen double-din, but I kind of wanted to turn my old OEM radio into an independent radio for my garage. I still have the stock speakers too.

Is there a way to do this without disabling that IC?

 

You have a cd in type deck corret? Cd plug on back of stereo

 

Yup. There's also a CD button, but no CD slot.

 

Yes, Line Out from the IC. The feed was this:

Tape Ribbon --> IC --> Main board.

This mod disables tape and tape sound processing making the feed:

Tape Ribbon (disabled) --> IC (disabled) --> AUX --> Main Board.