ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi all,
Have any of you had any experience to convert from a Philips laser CDM2 to CDM4 -11?
I have a confirmed dead CDM2 laser, with a brand-new CDM4 replacement.
I know that B&O had a complete kit, once upon a time LOL.
I've gone through the paperwork on this conversion, as I understand it, basically as follows:
On the Servo PCB, ONE poti (laser current adj) only
C2109 120nF --> 270nF
C2134 100pF - remove
C2141 390nF --> 470nF
R3106 1K --> 4.7K Poti
R3137 56K --> 120K SMD 1206
R3141 100K --> 160K SMD 1206
R3144 43K --> 39K
R3163 82 Ohm --> 15 Ohm
R3200 remains at 120K
Diode 1N4148 - Anode to IC6102 Pin5, Cathode to Ground.
Has anyone got any pointers to add, from experience, before I jump into the deep end here?
Menahem
Well, I jumped in the deep end, and purchased a brand-new CDM4 from Sebastian at Justone in Germany - he has a good stock of new units, expensive, but reliable.
Firstly, the CDM4 laser is NOT physically compatible with the original CDM2 tray, so the tray must be reamed out as shown, to allow the larger CDM4 counterweight to rotate freely all the way, and enough so that at the opposite end, the laser can reach the TOC.
Basically there are 2 notches on the wall which must be removed, and the wall thinned slightly.
Don't hacksaw off the CDM4's counterweight - it will fit, but the balance will be shot.
Here is the top side, showing the leaded component changes by yellow arrows.
At the right side, is the 7910 -10V regulator mod, with associated capacitors, which gives much more stable current to the focus circuitry.
Here is the SMD side, showing the new components. All components installed in this conversion are Vishay BC-Philips, in keeping with the original specs.
It's reading the CD's, and I am monitoring voltages and the HF "cat's eye" waveform to see that all is working OK.
At the right edge, is the blue and white wire connected to R3102, which is adjusted to 50 +/-5mV at poti R3106.