Hi,

I want to make a DIY boombox with an old Acura radio from 1995.

Front of Radio

Back of Radio

Sticker on Radio

Wiring Harness

Basically, I want to have small speakers in the enclosure, but loud sound isn't a priority. Mainly, I want to be able to use headphones with it as if it's a desktop tape deck and occasionally use speakers if wanted and I can always just upgrade those later. For those, I know I can get away with any old 4 ohm speakers. What's tricky for me is the conversion from straight 4 ohm output intended for car speakers to a headphone output. When in speaker mode, I want the volume knob on the deck to be the only thing controlling volume. But when headphones are plugged in and a switch is flipped, I want the output to go to the headphone jack, but also be lowered enough so I don't blast my ears.

I don't know much about voltages, mW, or any of the terms, just that you should generally match the ohms for speakers, and the consumer side of line-in/out, mic in, headphones, etc, but nothing in depth. I want to know how I can get the 4 ohm speaker signal down to a manageable headphone output; even if it means putting a secondary volume knob just for the headphones, I'm okay with it.

If it helps as a reference, when using my actual tape deck with my headphones, these are the specs for the headphone output of the tape deck.

I know with lots of advances in sound technology over the last 25+ years there's probably a semi to super easy solution to this problem; I've seen those tiny amplifiers on circuit boards you can use on tiny PCs or other small devices, so maybe a reverse of that, an attenuator? I searched for some, but they all seem to have a 3.5mm in and 3.5mm out. I don't know if the signal from the head unit is compatible level/voltage/mW/dB-wise or whatever. Whatever the item happens to be, I plan on using spade connectors for the output switch wiring to the speakers and whatever is needed for the headphone jack.

TL;DR: Need to convert 4 ohm speaker wire signal to headphone jack at corresponding volume level while being able to bypass and go straight to speakers if desired

Thanks!

So I have a 2006 dodge caravan SE, it's a pretty basic van without a line-in jack so I decided to solder one in. I pulled out the stereo and soldered this into the PCB using this pin sheet.

I soldered the front and rear right speakers + to the red wire (right) and the front and rear left speakers + to the white (left) and tied the all the - (negatives) together to the one ground wire.

It works and I can play music at an alright level, but it came with a few problems. 1. Turning on the radio/cd player seems push such a high voltage through the headphone jack of the phone that it crashes (that was terrifying). 2. Using the cd player without the phone plugged sounds absolutely aweful. It sounds alright until, frequently, it'll sound a little static-y. 3. While it plays fine, the audio is just slightly quieter than what I was hoping for.

So I've got a series of questions:

1. How could I prevent the stereo from frying my phone?

2. Is it possible to keep the cd player sound good AND have the headphone jack soldered in?

3. Is there a safe way to amplify the audio coming from the phone so it can play louder from the stereo?

If need be I can take out some perfboard and print a case.

EDIT: Serial # for the stereo: p05091506AE

EDIT 2: So I got everything rewired into the Audio L, Audio R, and Audio GND aaaaaand... nothing. It doesn't destroy anything and everything still works, but it looks like ratsta was correct in that it may not be wired up on the PCB itself. I think I'm going to wait a bit longer before trying anything more drastic, but I appreciate all the insight provided so far and I'm glad I have all this information available for later.

Hi. I’m attempting to add an auxiliary 3.5 mm jack to my 1999 Cadillac Catera. For my particular stereo which is a stock Bose equipped with a built in single disk CD player, there is no prebuilt solution I can buy. If I had the stereo that has a multi disk CD changer then there are aftermarket solutions like the PAC AAI-GM9 wire harness which is plug and play adding in aux.

If you’re asking why don’t I just use a cassette tape adapter or FM transmitter then my answer is they are too low quality. I also don’t want to replace the stock stereo with a new aftermarket one because I like stock.

I’ve opted to try this method which is to wire in directly an aux 3.5 mm plug that has Left audio, Right audio, and ground. I watched a few youtube videos and apparently this is very doable. People tend to not actually solder in the wire to a PCB but just tap into a pre existing wire which is what I’m aiming for here. This video gives a breakdown of what I’m going for: Youtube

So where I’m at now in the process: I’ve taken out the stereo and disassembled it. I’ve begun to analyze the integrated circuits but it seems that the ones that matter the most I’m unable to find the pin outs for - maybe someone can lead me in the right direction in finding these pinouts for these two similar IC’s:

09365321 ©1986 TI ©1998 TI R1B5D020FN 980 W-85A4X9W

2. 09366112 ©1986 TI ©1998 TI R1B5D025FN 980 W-88A0D8W

Both of these IC’s are on what I think is the motherboard. I’ve included pictures here with some annotations. What I think I’m looking for is the Left, Right, and Ground coming from the CD player wires which is 3 out of the 14 red wires. Let me know if I made false assumptions or if there are certain areas I should be focusing on more. Does anyone know where the data sheets are for the IC’s above? Any help is appreciated. Thanks.

I’ve found these two IC’s which are on the CD player PCB: Technics and NEC

Images here: Public Flickr photo album