Laser in CDM1

[diyman]

For the Philips CD960, is the laser diode supposed to be on all the time or only when it plays a disc??

😕 😕
ckt

 

[phimor]

Hi,
I don't know the exact model you refer to, but I have about 10 players with the CDM0/1 pick up, and they all shut down the laser if there is no disk. Also when not spinning.

Cheers

Philippe

 

[Terry Keith]

I am looking for two CDM1 units to restore two CDX players. Anyone have available units?

Thanks!

The Restorer in Ohio

 

[phimor]

Hi Terry,

sorry none of mine are available for parts (they all work - they did not when I got them).

Try
http://www.ersatzteil.justone-schnepel.de/html/bildergallerie1.html

Also I have seen some on German ebay sites.

I assume you have tried replacing the 33uf caps already?.

Cheers

Philippe

 

[Terry Keith]

I have swapped out the CDM1 boards with the components on them to another CDM1 assembly and they do work.

I am in search of replacement laser diodes for the light pin tube.
This particular diode is a three pin type with a grounded case similar to an older type metal case transistor with a small orientation tab near the pin that's grounded to the case.

Thanks for the site url you sent. The pictures are great, but I don't read German!

Another gentleman was pursuing replacement laser diodes on this site earlier this year and said he'd found some and had them on order, but I have not been able to locate his followup post - if it exists.

I believe I have a process for removing the old diode and replacing it with a new one if I can get some NOS or replacment diodes of the correct type.

Cheers,

Restorer

 

[Silver Eagle]

IMHO, most old Philips CD player's laser diode can output sufficient power, but photo diodes have problems.

So, maybe you can check photo diodes first.
Or check Servo loops. (Focus and Radial control)

 

[Terry Keith]

Do you mean the chip assembly that is glued to the radial arm?

The 8 Pin chip that has the flex cable attached?

TK in Ohio

 

[Silver Eagle]

Yes. The 8 Pin chip contants photo diodes.

If you de-solder the flex cable, you will find a small window under the chip, and you can see the die.

I tried many times to fix damaged CDM-1 laser pick-up.
Never success!

But I notice most laser diode can output sufficient power.
So, I think it must be something worng elsewhere.

 

[Terry Keith]

Thanks for the information!

I have confidence that CDM1 units can be successfully restored with a combination of skill, patience, ingenuity, and collaboration!

Best Regards,

Restorer in OHIO

 

[Gasho]

How can i replace laser diode in laser optical assembly without using a force?

 

[Salar]

I will resurrect this thread for some useful information:
First of all, the diode used is a Sharp LT022MC, same diode as being used
in early Sony mechs.
A friend sent me a disassembled laser tube.
I will measure it and put the data into my CAD program.
As he stated, it was not easy to remove the diode. It seems to sit stiff
in the housing and he had to remove (and accidentally destroy) the
prism above the laser and the diode´s window. Also Looks like the quarter photodiode receiver can´t be removed without breaking it.
What strikes me is the fact that the laser diode sits in the tube without play.
It is said that not two diodes (i.e. the placement of the emitting silicon in the housing) are the same. Angle in a clockwise manner might play a role because
of astigmatism. Nevertheless, if a diode is worn out, replacement might be easier than with Sony players which have a diffraction grating.See also this thread:

http://www.diyaudio.com/forums/digi...r-pickups-why-not-replacing-diode-only-4.html

Here are images of the CDM-1 laser pins. Check also this link in German:

CDM1 Linsen

 

[Mike P]

Has anyone here actually managed to replace the laser diode in a CDM1 yet?

 

[Mike P]

I have a suitable candidate for attempting a diode replacement (a Marantz CD84 with low laser power). I have some genuine LT022MC diodes so I might give it a try.

Any ideas how to gently remove the old diode? Dissolve the glue with acetone?

 

[ManoloMos]

Hello. I don't have any experience on these Philips players. But, seeing the pictures, is a thing very clear: Don't remove the photodiode array from the aluminium piece.

Hi Mike P. Can you publish any picture or the laser diode placed?

The market is very scarce of reliable and not fake LT022mc or equivalent laser diodes.
This is the only decent that I've found, a LT023mc that is a bit better in phase performance to the LT022mc, but it is not cheap.


LT023MC semiconductores caso: Estandar Marca: Sharp | eBay

Best regards

 

[Mike P]

Hi ManoloMos,

I bought diodes from the same UK based ebay seller that you linked to in this thread.

Do you think the LT023MC is a straight drop-in replacement for the LT022MC?

I've bought several items from Little Diode and they all been OK but some people on this forum have received fake parts from him.

 

[ManoloMos]

I didn't know that Little Diode Shoph had been affected with counterfeit components. LT023mc is a little better in phase than the LT022mc, but now, I don't know what to think abot the LT023mc in Little Diode. Who knows...