Problem Cambridge D500-SE

[gruchol]

Hello, I have Cambridge D500-SE which don't readed compact disc. Every time when mount compact disc after few seconds show "no disk". I thinked problem is with the laser so exchange laser another from worked Sony CD player. Problem still the same when close CD tray after few seconds show no disc. I noticed when close the CD tray laser lens go down for few seconds and later show "now disc". If I hit down compact disc then laser lens go up and down and music play.
Somebody know where is the problem and can tell me solution?

Ps. Sorry for my english.

 

[Mooly]

There could be many reasons, however I would begin by making sure that all the mechanical aspects are OK before even thinking about looking deeper. Check that the spindle and sled motors are OK and that any microswitches on the mechanism and tray assembly are clean.

Probably a different mechanism but this is the type of procedure.
Sony CDP790 and KSS240 Restoration Project

 

[gruchol]

I checked mechanical parts and micro switches ( with multimeter). Looks all ok.
I recorded a movie with an old laser:
YouTube
YouTube
YouTube
YouTube
On the last movie I recorded where it is the problem. On the Sony CD player always when closed CD tray first laser lens go up and down like focusing.
I don't know which part in CD player is responsible for checking the laser up and down on the start ?

 

[Mooly]

The main syscon (system control IC) looks first for all inputs to be correct such as the microswitches and only then will it perform a 'focus search' routine where the lens goes up and down three times. If focus on the reflective disc surface isn't found then it defaults to the 'No Disc' message.

It would be very very rare for the any of the main IC's to be faulty, problems are almost always elsewhere.

 

[gruchol]

I noticed now if upside down Cd tray the laser lens go 3 times series: fast go down, next slowly to center.
Looks like no have signal to up lens ;/

 

[Mooly]

So begin by looking with an oscilloscope at the focus coil drive amplifier and see if the focus search ramp waveform is present. Also check whether the waveform is swinging correctly above and below the (assumed) zero volt lens resting position.