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[Valentin]

Hi mates,

My 3.0 MV6 from 1996 doesn't have the Bose system. But the sound seems to be pretty nice.
It has a CD changer in the booth, which is stuck (there is one CD that cannot eject and the mechanism looks like it's bent).

I wanted to unpin the 3 lines IN and replace them by a 3.5 jack, as I already did in my Calibra (on which I partially rebuilt and retrofited a genuine Bose system for Calibra).
This mod allows you to keep the OEM unit and you can also put a bluetooth device on the jack, hide the stuff in the glovebox and you have all you need from your phone

The mod is quite simple, you unpin the LineIN Right, LineIN Left and LineIN Ground, then you crimp respectively right, left and ground on new pins that you fit into the 10 poles connector, same place as the wires from the changer. But it doesn't work

I guess there is an information missing for the radio to see the jack signal, but I don't know how to do. On the Calibra I remember there was an extra ground to simulate the CD Changer, but I'm not sure about that and I cannot remove the unit right now to check the wires on this car.

Nobody ever made this mod on the Omega ?

[TheBoy]

I never did it on an sc804, only on newer ones.  I found it needed a small circuit as well just to bring the levels and impedences to what they should be.

I think it's a Philips setup, so you might be better with a CD Changer emulator, that will sort all the level issues, as also any protocol issues that might be fighting you?  Emulators were a thing back around that era.

[Valentin]

Oh I see, it needs a bit of electronics knowledge about D2B protocol... Well, it's too complicated for me as I don't find any changer emulator for this particular Philips DC012 device, and I don't know anything about microcontrollers.

Will go for a new retro look Blaupunkt head unit, loosing the radio display on the MID

[Doctor Gollum]

No reason why the CDC aux in hack won't work. It's a useful addition and keeps all the other functionality 

https://rutube.ru/video/9802f7b8d2ec6006d91305a0ad55355a/

Fundamentally this is the mod but double check the pins/wires you need to tap into on your set up.

[TheBoy]

No reason why the CDC aux in hack won't work. It's a useful addition and keeps all the other functionality 

https://rutube.ru/video/9802f7b8d2ec6006d91305a0ad55355a/

Fundamentally this is the mod but double check the pins/wires you need to tap into on your set up.

I think that's what he tried.  Earlier Philips setups needed the CD Changer to be present and working though, and not in an error state.  I found this out with one of my Rovers which was prone to laser wear - it it couldn't read the CD and think it was playing, you couldn't feed audio into the headunit.

[Doctor Gollum]

It's a cheeky hack so a shame if it doesn't work.

That said, aftermarket with steering wheel adaptor will keep some of the factory usability re steering wheel controls, but the trip computer is a standalone system that happens to have a display input from the head unit. So the only loss there will be channel/track displays but the new head unit will have those.

[Valentin]

The connections from the CD changers are :
- Line in Left
- Line in Right
- Line in Ground
- D2B+
- D2B-

What I understand is that D2B is the protocol and the information travelling through both wires gives the radio unit the right information about the state of the changer. Thus, we should be able to know what is the resistance value there have to be between both wires to indicate the radio unit that the changer is in working state, indefinitely.

I got the service manual from the Philips DC012 but didn't find this value yet.

First I will try to repair the changer which is stuck, then if it works properly I may be able to mesure the value between both wires. Then remove the changer and put a resistance in place.

Or am I totally wrong ?

[TheBoy]

I think if you can get the changer to work, then you can inject the audio on the audio lines. I suspect that currently, because it's in an error state, the HU is not switching to the incoming audio lines.

The D2B is an I2C type bus from memory, so you're not looking for a resistance there, it's a bus that carries a digital signal (for state, operation, and commands).  These types of buses are terminated to reduce signal bounce, so you will see an impedance at both ends.

[Valentin]

Ok I finally got the changer to load CD's and try to read them. It struggles a lot to find tracks and to stay on them, jumping every time the car drives over a small road irregularity.

BUT, plugged the jack to the L/R/GND lines and now it works just fine ! Until the changer's death

The jack is plugged to a Bluetooth receiver hidden in the glovebox

[TheBoy]

The lasers on those Phillips units are prone to failure with use. Fortunately replacement lasers are (or used to be) readily availlable. Bit of a ballache to have to change it when you don't actually need it though!