Yes and no.
If you look at the last page of the Beosound service manual for the CDM12 version, you see the changes they made.
CDM 4 needs -5V and if your system was made for the CDM12, your power supply may be missing those parts (12R113, R23, C61, D7 and TR2).

But why would you want to install an old CD mechanism? (Unless you have a known good CDM4 idly lying around somewhere, of course.) CDM4 has its own problems.

Did you replace the CDM12 yourself? Was it a brandnew replacement unit or a used pickup from some other CD player? Did you follow all the test and adjustment steps laid out in the service manual?

Excellent news, Bill! That was my thinking as well. I appreciate you taking the time to share your experience.

manfy, I saw these notes in that service manual too but could not make sense of if anything needed modification or not. Looking at the companion circuit board for the CDM12, it is marked as supplying both 5V and 12V via the P200 connector that goes to the board behind the CD. So hopefully it should work with Ouverture CDM12 -> Ouverture CDM4 as well!

Reading about the mechanisms, it is my impression that the CDM4s are a lot less error prone - save for the infamous capacitor, but that is at least an easy fix.

So... I might look into aquiring a working CDM4 kit even if it feels a bit like cheating by not fixing the CDM12. I did replace the CDM12 laser unit myself with an unused genuine Philips one. Prior to this ,it did not spin at all (no focus I guess). Not sure what tests or adjustments are needed after this? The builtin test mode works fine, moving the laser etc. But that is maybe better explained/discussed in my related thread:

Martin wrote:

Reading about the mechanisms, it is my impression that the CDM4s are a lot less error prone - save for the infamous capacitor, but that is at least an easy fix.

Far be it from me to talk you out of it! Sound quality is something like a religion to some people -- in fact for me too. But in the end it's a very subjective thing and you should go with what suits you best.
The CDM12 Industrial has a very good reputation, so it's nothing to look down at. It has a 3 beam technology, which makes it faster but of course also more error prone when it starts aging. The simpler single beam CDM4 doesn't exhibit that ailment.

Martin wrote:

manfy, I saw these notes in that service manual too but could not make sense of if anything needed modification or not. Looking at the companion circuit board for the CDM12, it is marked as supplying both 5V and 12V via the P200 connector that goes to the board behind the CD. So hopefully it should work with Ouverture CDM12 -> Ouverture CDM4 as well!

That's easy to verify. Page 15.1 of the service manual shows that the PCB89 (CD interface) has a connector P67 has -5V on pin 1. This voltage is not needed on the CDM12 mechanism, but it IS required for the CDM4. (On the CDM4 this connector goes to the servo board 8.)

If you can measure -5V on your P67 between pins 1 and 3 (GND) then you're good to go.
If you measure 0V then you need to look at the power supply (PCB 12) and you need to find the location of those components 12R113, R23, C61, D7 and TR2 and add them manually.
But to be honest, I find it hard to believe that B&O really skipped those components for units shipped with CDM12. They would save only 10-20cents per PCB, but add the cost of creating a second board version, add costs of stock keeping, etc. etc. That sounds really stupid - but well, who knows!
In any case, you have to check that you have taht -5V supply on connector P67.1. The CDM4 won't work without it.

Hi Martin,

Just to be more clear about my swap, I changed out PCB 8 + Module 97 (CD Mechanism complete). The older parts came from a Beosystem 2500 and were swapped into my Beosound 4000.  The BS4000 at the time had the CDM12 Industrial (Module 97) and PCB 8 (servo motor system and decoder) was much shorter than the corresponding part from the BS2500. The two parts together must go as a pair, the complete CD mechanism and the servo motor system/decoder.

The older parts will fit in the Overture (BS4000) physically perfectly, all connectors match the cables in the cabinet to connect to the rest of the system. If I recall correctly it's a little tight down by the headphone PCB but it will all squeeze in.

I'm sorry if this wasn't more clear before.

Bill 

Bill, yes, that is exactly how I interpreted it! But thanks for clarifiying!

@manfy, -5V confirmed on P67 between pins 1 and 3 (GND)! 🙂

Now I know that I have the possibility to switch CD drive type if needed!

Many thanks to you both, Bill and manfy!