Philips Cdm’s mechanical alignment

[Scorpio(DDMF)!]

The cdm4/19 in my Philips needs an optical alignment

Unfortunately, it’s service manual doesn’t contain the procedure for it. All I have is sm for the cdm2 – but everything except the pictures is in Dutch… I’ve translated parts of the text with some success, but the keywords are unknown to the online translator

Searching the forum, I’ve found some mentioning of it, but sadly, it points to the service manuals for the players.

Does anyone have an sm which describes the procedure in English? Also, I would be very grateful for any pointers or someone’s experience with the procedure.

Thank you in advance

P.S. I will post the Dutch sm for the cdm2 if needed.

[Scorpio(DDMF)!]

The purpose of the procedure should be the aligning of the laser head with the cd’s data side when resting on the turntable. They should be in parallel.

As I’ve understood from the pictures in the service manual, it is done with a (halogen?) light source, a clear disk and good eyesight . The part which is in Dutch explains the procedure in detail…

I’ve attached the 3 pictures of the process and the whole “alignment page”, in the case that someone with knowledge of Dutch could help?

Cheers!

[Scorpio(DDMF)!]

Clearer pictures of the procedure :

Cheers!

[oshifis]

Could someone please explain, what should be seen/aligned? Thanks

[Scorpio(DDMF)!]

Originally posted by oshifis
Could someone please explain, what should be seen/aligned? Thanks

The best (and only) description of the process was given by Tubee :

Originally posted by tubee
In that case Henri, the alignment of cd surface with laser arm movement is not correct, not parallel, and thus focus isnt right on end of cd compared to begin.

This can be adjusted with a clear cd. Make a clear cd of methacrylate 2mm thick, i did it that least. hole made with a large scissor, outer edge simply grinded on a table grinder.

Lay clear cd on the spindle, look in the reflection of a tubelight, check if reflection Tubelight is aligned with the reflection of laserlens. (But not sure if laserlens has a flat outerplane, if not you don't see a straight line in lens.) The human eye is very good with parellel lines (10 times better then normal sizes estimated) so its rather accurate.
Check it with different positions of laserarm, and with tubelight horizontal and vertical. Untighten first the screws of laserarm somewhat, adjust position of arm towards cd surface slightly, and when all is aligned tighten again. Nice job for a rainy sundaymorning.

A cdm service manual declares this also.

Sadly, it doesn't detail on the "parallel lines" or the exact position and angle of the neon light (which also isn't quite clear from the pictures in the service manual ).

Cheers!

[Scorpio(DDMF)!]

Well, as it would seem, the cdm4 series have self-centering optics and thus don't need this procedure!

This is the only information related to this matter wich I could recieve on the local forum, and I assume it's the correct one?

Cheers!

[tubee]

When the cdm stops halfway a cd, the alignment is neccesary. Also when you dismantle the laser unit, or fit a new laser unit.

It is rather easy, there are notches to align the rafoc (RAdial drive and laser FOCus unit) itself, when cdm is stil not aligned try to correct it as shown. When stil it cannot align properly break off the plastic pins to increase setting angle of rafoc.

Purpose af aligning is an equal distance between laser focus point on begin and end of disc.

Alignment (again!) compare the reflected line from a tube-light on the ceiling on the laser if it is in line with the reflected line on a clear cd disc (a clear pmma sheet of 2 mm thick) The TL must be above you at a certain angle and the tube must be directed in the vieuwing direction. Check alignment in x-axle and y-axle

Btw don't touch the laser connections, very sensitive for ESD!! When you dismantle cdm, electrically short lint cable with paperclip