CDM-2 Servos - Static vs. Dynamic

[amc184]

I was playing around with a few of my CDM-2 based CD players the other day, swapping the mechanism out of a player I had junked (a CD650) into a CD150. The laser mech from the CD650 just would not track well; tracks one to five were fine, track six was getting marginal, and beyond that it would not track at all. I checked the normal things (friction in the bearings etc.).

It was then that I did some reading, and came across an issue I had never considered before: Static vs Dynamic CDM-2s. It seems that the CDM-2 had two types of radial drive, static and dynamic, and there are different servos for each. This results in four different servo panels:

- No.5725 (static radial drive, on board microcontroller)
- No.5768 (static radial drive, off board microcontroller)
- No.5826 (dynamic radial drive, on board microcontroller)
- No.5827 (dynamic radial drive, off board microcontroller)

And within the model CDM-2/10 there are eight variants:
- Static models; 0000 (Hi-Fi), 0001 (Top Hi-Fi) and 0003 (Leuven)
- Dynamic models; 0008, 0300, 0301, 0303, 0307

Now at the moment I have three CDM-2 laser mechs (a 0000, a 0001 and a 0301) and four servo boards (three 5725s and a 5827). I'd like to run the 0301 laser mech in my Philips CD150, but I need a 5826 servo panel to do this. I've had a look at the schematics of both the 5725 and 5826 servos, and there isn't a whole lot of difference, about half a dozen passive components in the radial drive.

My big question is: Are there any other differences between a static and dynamic servo, especially with the microcontroller programming? Am I going to get a servo that works with dynamic CDM-2s in a CD150 by swapping out those half dozen passive components? I have shown a block diagram of the servo below, with the radial tracking and drive portions highlighted.



And before this I thought a CDM-2/10 was just a CDM-2/10 . Anyone out the care to elaborate on the difference between the static and dynamic radial motors? And does anyone know if the other CDM-2 variants (the /29 etc) are static or dynamic? I would guess dynamic, but I'm not sure.