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Discussion Starter #1 (Edited)
Audio_R and Audio_L are swapped!
Ensure to solder them correctly.
Currently I'm unable to fix the pictures...
The notice will be deleted once it's corrected.



Hi all, I recently spent some time trying to make it work.
Well, it's working great, so I'm making a guide. :)
In case any image is too blurry (sorry, AO forum shrinks them automatically), here you have them full-sized:
https://postimg.cc/gallery/g9n00w34/


Parts you need:

2x 1K resistor 1/8w
2K2 resistor 1/8w
4K7 resistor 1/8w
10K resistor 1/8w
Electrolytic capacitor 1uF 16V
Electrolytic capacitor 10uF 25V
BC547C transistor
BDX34C transistor
74HC14N logic circuit
Small perfboard / DOT PCB

All those parts are cheap and very easy to buy at a local electronics store.

Obviously, you need a bluetooth module! I bought this one, and the sound is very good, doesn't make strange noises or interferences.
Also, this module has a relay that switches to an external audio input when the bluetooth is not playing.
This way we can connect the aux-in to that input. It will be always active until you play something using bluetooth.


https://www.aliexpress.com/item/CSR64215-Amplifier-4-2-Wireless-Lossless-Bluetooth-Audio-Stereo-Receiver-Board-Integrated-Circuits/32870155459.html


The circuit is based in the original Angeloffrief's work: AUX-IN Becker BE2580 Porsche PCM1

The circuit. It has three parts:

- Faking the presence of the cassette with a simulated signal. The original circuit worked pretty bad, I had to push a lot of times the cassette button to make it work.
Also, as it directly pulled a signal from the radio to fool the cassete presence, it caused weird noises when listening to the FM radio.
That's why I tried isolating the signal with a TTL buffer. And it worked!
Now the radio works great and the cassette engages almost perfect, some times I have to push it twice or three times but no more. Before, it was a nightmare.

- Second part of the cassette circuit. This is the same as the original circuit.

- Powering of the Bluetooth module. The audio board only has permanent 12V, so directly plugging the module would drain the battery.
As I didn't want to set up wires between the ICS boards, cause I preferred to make it as clean as possible, I had to make this little circuit.
We have a 5V power that only works when the ICS is powered up, so I use it to power the circuitry and also enable a transistor that only switches on the permanent 12V to the BT when the ICS is on.



(clic for larger image)



Where to solder the wires on the ICS audio board:




Cut this tracks in the underside of the board:




Connection of the BT module:



If by any means you hear any hissing you can try to load the output of the BT module, so the amplifier has a small load:
You'll need 2x 47ohm resistor 1/8w



This was my setup. I used other component instead the BDX34C transistor, just because I found it in my disaster box :heh:.

The're are few changes, I removed the relay from the beggining because I wasn't going to use the Aux-in, neither I wanted to hear it clicking, but it's barely audible, it's just me, I'm special :).
Also I soldered the resistors to load the output, I didn't try without them.

As the cassette mechanics are no longer used, I used it's screws to hold the boards in place.

Video of it working:
 

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Fantastic write up, thank you!

My girl has been complaining for a whole year about how the GT had a Kenwood with bluetooth and the 166 doesn’t even have a än aux... I need to fix this to shut her up :blabla::rotate:
 

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Well done, but that's a lot of work.

I just use a Bluetooth to FM transmitter, for the cost of a tenner off ebay. It's small, just sits neatly in the lighter socket, and my phone pairs to it as soon as I start the car, and the ICS has the frequency of the transmitter as a preset channel. I can have my Google Music through it, and all phone calls, voice apps and messages too, as it has the benefit of having a small microphone in it. And the sound quality of the music is the same as the sound from the CD changer, (not that I use that anymore!) with no interference or anything untoward, no wires, soldering, or disassembly. My cassette and CD changer and amp are all still stock, working and untouched.

Attached picture. You can even put it in the rear lighter socket if you'd prefer, so you can't even see it then. I won't recommend a particular make, but suffice to say this one is Chinese, cheap and off ebay. I'd be lost without this now - who had CDs or tapes knocking about nowadays!?
 

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Discussion Starter #5
The sound quality between using a FM transmitter and directly feeding the ICS is huge. Wouldn't recommend it.
It isn't that much work. You got it done in a saturday afternoon. Better than thinking in death while watching outside while it's raining and cold :hehe:
 

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Well done, but that's a lot of work.

I just use a Bluetooth to FM transmitter, for the cost of a tenner off ebay. It's small, just sits neatly in the lighter socket, and my phone pairs to it as soon as I start the car, and the ICS has the frequency of the transmitter as a preset channel. I can have my Google Music through it, and all phone calls, voice apps and messages too, as it has the benefit of having a small microphone in it. And the sound quality of the music is the same as the sound from the CD changer, (not that I use that anymore!) with no interference or anything untoward, no wires, soldering, or disassembly. My cassette and CD changer and amp are all still stock, working and untouched.

Attached picture. You can even put it in the rear lighter socket if you'd prefer, so you can't even see it then. I won't recommend a particular make, but suffice to say this one is Chinese, cheap and off ebay. I'd be lost without this now - who had CDs or tapes knocking about nowadays!?
I'd fancy giving that a crack.
Could you please post the link to the one you bought?
I had a quick look and there any too many to choose from!
 

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Well done, but that's a lot of work.

I just use a Bluetooth to FM transmitter, for the cost of a tenner off ebay. It's small, just sits neatly in the lighter socket, and my phone pairs to it as soon as I start the car, and the ICS has the frequency of the transmitter as a preset channel. I can have my Google Music through it, and all phone calls, voice apps and messages too, as it has the benefit of having a small microphone in it. And the sound quality of the music is the same as the sound from the CD changer, (not that I use that anymore!) with no interference or anything untoward, no wires, soldering, or disassembly. My cassette and CD changer and amp are all still stock, working and untouched.

Attached picture. You can even put it in the rear lighter socket if you'd prefer, so you can't even see it then. I won't recommend a particular make, but suffice to say this one is Chinese, cheap and off ebay. I'd be lost without this now - who had CDs or tapes knocking about nowadays!?
I'd fancy giving that a crack.
Could you please post the link to the one you bought?
I had a quick look and there any too many to choose from!
Hi there. Sure, this is the one that I use :

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/263302071388
 

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Get well soon mate
 
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