Help for a Naim CDI (CDM4/x)'s laser

[marcot]

Hi everybody:

my NAIM CDI doesn't want to read discs any more (ERR, no TOC reading).

I was told that my mech's laser (CDM4721 or 27, don't know) is dead (by two professional not-naim technicians).

Naim doesn't want to help me with any technical suggestions.

I have read many things on the web about this problem.

Now my question is: is that possible to use a CDM4/19 pick up instead of another one? If it is, do I have to change some electrical values somewhere in the servo board or it fits automatically?

Thanks a lot

Marco

 

[Fantasio]

Yes : replace CDM4/25 /27 laser

Absolutely!

You can take a CDM4/19 laser arm and transplant it to a CDM4/25 or CDM4/27.

However you will have to adjust the focus and laser power pots to the new laser. I had a CDS which had had a new laser fitted from a CDM4/19. The guy who sold it to me had done the job by himself.

I advise you to grab a CDM4 service manual (any CDM4 equiped cd player service manual will do) in order to get the instructions on how to disassemble / reassemble the rafoc and how to properly align it on the CDM4/25.

CDM4/19 donor cd players are quite easy to find.

Hope this helps.

 

[Web Wolf]

For Fantasio

I've a similar problem because I bought a NAIM CDi in ebay a little time ago and now the player, when I insert a cd, try to read it and then it writes an error message. NAIM assistance says that the problem is that the lens in exhausted. As I found here, I should have the CDM4/27 mechanic. I found a CDM4/19. Really if I replace the laser it will work again ? What are the differences between mechanics ?

The assistance said to me that often similar mechanics didn't work on NAIM players.

Do you know where could I find a CDM4 service manual or is it possible to contact the guy ho sold you the CDS ?

Please help me !!!

 

[powerflux]

I've a similar problem because I bought a NAIM CDi in ebay a little time ago and now the player, when I insert a cd, try to read it and then it writes an error message. NAIM assistance says that the problem is that the lens in exhausted. As I found here, I should have the CDM4/27 mechanic. I found a CDM4/19. Really if I replace the laser it will work again ? What are the differences between mechanics ?

The assistance said to me that often similar mechanics didn't work on NAIM players.

Do you know where could I find a CDM4 service manual or is it possible to contact the guy ho sold you the CDS ?

Please help me !!!

first of all, try to clean the lens with a dry q-tip. 90% of the cases is a dirty lense. make a circular motion from the inside out with a little bit of pressure. be carefull ofcourse not to press too hard!!

 

[io]

Cdm4/25

JusTone Lasereinheiten. CDM4/11 Ersatz Lasereinheit Laufwerk Lasereinheit, Laserpickup, Laserunit, Pickup, Laser, Laserkopf

 

[Web Wolf]

Thanks to all who gave me help ! I've just found a CDM4/19 meachanic on ebay (seller says it's status is new ... I hope so ). What if I substitue the laser only ? Have you got a CDM4 service manual ?

Thanks boys

 

[amc184]

Where did you find a new CDM-4/19 on eBay? I've only seen used ones on there.

 

[Web Wolf]

Mah ... I think it's a question of ***. Seriously, I hope so. The seller said to me that he has taken some parts from old unsold machines ...

Is out of there somebody ho could help me to trasplant the optic from the CDM4/19 to the CDM4/27 and to calibrate the trimmers ?

Ah, another thing, ... now I can hear a light buzzing from the cdplayer, an electrical noise, but not from the loudspeakers.

 

[io]

Cdm4/19

Where did you find a new CDM-4/19 on eBay? I've only seen used ones on there.

Hi

Hungary sales Philips CDM4/19 NEW Original pickup.
circa 20 US dollar/each

j PHILIPS CDM 4/19 TELJESEN J BONTATLAN CSOMAGBAN!!! - eladó - CD játszó | Expressz.hu

 

[Web Wolf]

Hi everybody, I'm really desperate !! I replaced the optical unit of the CDi (I took the laser from a CDM4/19 though mine is a CDM4/27). The new optical seems to work, but the player, when trying to recognize a disc, make two complete revolutions and then the message "Err" is displayed. I replaced all the capacitors on the control board of mechanics,too (certainly it is always a good thing), but the behavior of the machine has not changed. Looking at the optical, I can see that it moves itself, focusing etc.

Do you have the opportunity to speak with some experts on this machine and ask them what could be groped?

If the DAC is ruined obviously It would not make sense to repair it. :-(

Thanks again
Simon

 

[Fantasio]

An ERR display message means the CDP was not able to read the TOC on the CD. It does not mean the DAC is ruined.

You may have to adjust the trimmers for your new laser optical unit. One is for the
focus and the other one is for the laser power.
To get a hint at how to do that, have a look at the Philips cdp service manuals at hifiengine.com.
The procedure is quite similar for all Philips CDM and SAA72xx based units.

 

[Web Wolf]

Hi, perhaps you're right, but I'm thinking... why the optical unit should have a different alignment than the old ? If they are equals

There is a photo of my control board. All capacitors are substituted. Perhaps I should use the trimmers, but I see two diodes, too: if I want to substitute them I should measure them, but how could I do ?


PS: I had the same behaviour with the old optical unit.

http://img338.imageshack.us/img338/7349/dsc03213h.jpg


Bye and thanks

 

[amc184]

but I'm thinking... why the optical unit should have a different alignment than the old ? If they are equals

There is variability in the laser diodes and photodiode pickups, having to adjust a servo when you change RAFOCs is completely normal. Make sure you adjust it carefully, in line with Philips' service instructions.

The Naim probably doesn't have a service manual, or at least one that's publicly available, so I have attached the schematic, board layout and adjustment procedure for this particular servo board. The part you'll want to follow is the section marked 'B4 LASER CURRENT ADJUSTMENT'.

The ZIP file contains a PDF. For some reason this forum allows larger ZIP files than any other.

 

[Web Wolf]

Thanks for the help ! Very precious. So I should need only a simple tester ? For the ohm I've a RLC bridge, too. The unic problem is that I need the "test disc 5A" mentioned in the table to adjust voltages. Do you know where could I find one ?

Another thing: I didn't understand the column near to "MODE", the one with voltages. The other thing is that my servo board is placed inverted, so it's very difficult to measure.

Thanks again

 

[amc184]

So I should need only a simple tester ?

Yes, just a multimeter that measures voltage and resistance.

Do you know where could I find one ?

On the shelf next to your stereo! Just use a normal, pressed CD.

I didn't understand the column near to "MODE", the one with voltages.

They refer to the point at which you must place your multimeter probes to take each measurement. They are marked in red on the PCB layout diagram.

The other thing is that my servo board is placed inverted, so it's very difficult to measure.

Yeah, most players are like that. I often temporarily solder wires to the testpoints, then clip test leads to the appropriate wire when I need to.

 

[johnm]

I have successfully replaced a CDI mechanism in the past. I have a ZIP file (too big to put here) which contains all the information you need for adjustments. Please PM me with your e-mail address.

Incidently if you get ERR messages in the future best cure to try first is a Naim CD5i puck - stops slipping from the AWFUL top-hat pucks. I discovered this a few years back now and many people have tried it successfully since.

- John

 

[Web Wolf]

Excellent, Thanks to all. How could I send you a PM ?

 

[Web Wolf]

I've read on the internet that the Philips CD 5A cannot be duplicate because it contains praecise informations on jitter and other things that would be altered with the copy.
Is it thrue ?

If so, in order to optimize the lens, I should buy a philips test cd 5A, but where ?

 

[amc184]

If so, in order to optimize the lens, I should buy a philips test cd 5A, but where ?

As I have already explained; you don't need test disc 5A to set the laser current, just use any pressed CD (not a burned one). Jitter has nothing to do with setting the laser current or focus offset.

 

[Web Wolf]

Excuse me, but the laser should become of different levels in a musical signal isn't it ? Isn't better a pink noise or white noise cd ?

Another thing: when, during calibration of voltage, it says to connect to ground, does it means connecting to player case or to the common ground (star ground usually used by NAIM machines) ?