Help needed from Martin or other CD drive specialists

[YannChris]

Hello Beoworlders,

I’m not so lucky on my Beocenter 9000 restoration project, here is the situation for the time being:

I have 2 CD drives :

1 – One CDM 2/10 which was initially in my Beocenter.
It has been recapped by a professional using the CK-003 capacitor kit bought at Beoparts. The 1,5 mF capacitor has not been changed, as stated in the instructions sent in the kit. The original capacitor was a sort of bubble.
BUT unfortunately, while I was doing tests before the exchange, the unit touched the bottom of the Beocenter and a smell occured before I could cut the power.
Here are pictures of the unit:

 

2 – One CDM 4/24 bought second hand. The seller said that capacitors were replaced.
I had the board audited by the professional who took care of the other drive which did not find broken traces or dry joints
Here are pictures of the unit :

The symptoms are shown in the 3 videos below, made without disc but the behaviour is the same with a CD in place.

As an alternative, I have found a classified for a functional Philips CD 150, but the CD is held by a clamp and not by the center as on my drives.

So I wonder what to do without risking a major failure:
– Exchange the servo boards between the CDM 2 and CDM 4?
– Place the servo board of the CD150 on the laser of my units?
– Place the disk holder of one of my drives on the CD150?

OR… send my drives to a Beoworlder who could repair them at my cost?

As I’m not so skilled in electronics, the latter solution would really be great.

But I’m open to any good advice or help.

Thanks by advance,
Yann.

[Dillen]

Did the smell come from the drive?
Can you still smell where it came from?

It’s not uncommon to see the ribbon cable damaged where it is held by the black clip.
The cable goes around sharp corners and it takes only very little pulling to damage the cable.
It’s also very short – only long enough to reach the board socket. Inexperienced repairers
can accidentally pull it when dismounting the board from the drive, because they may
not know the cable is there.
I would check the cable on the drive that wasn’t burned.

Martin

[YannChris]

Hello Beoworlders,

To Martin: Sorry but I could not localize the smell.
I always carefully removed the ribbon cables using the ZIF connector on the servo board.
I agree with you, there are sharp angles on the CDM 4 and I hope that the seller took care when he recapped the unit.

To all: Today, I exchanged the laser units from one drive to another, here are my findings:

CDM 4 servo with CDM 2 Laser: plays well on an 8 tracks CD except a noise when moving to a track at the end of the CD, but does not work on a 18 tracks one. This behaviour was identical on original CDM 2 unit before the “smell incident”. See these videos:

CDM 2 servo with CDM 4 Laser: same symptom as on full CDM 2 unit after the “smell incident”. See this video:

I come to the conclusion that something is wrong on both servo boards as no perfect result is obtained.

When it comes to lasers, I suppose they are still functional, but I suspect the CDM 2 one needs some tuning and I have neither knowledge and equipment to proceed. I have no idea for CDM 4.

So “I send an SOS to the world” and would be grateful if somedy with the know-how could take over this repair. Of course, I take all the costs.

Thanks by advance and kind regards,

Yann.

[matador]

Hi,

Idiot question: did you try with (a lot of very) different discs? If no, maybe it is related to the “density” of data on the disc? I think I’v read somewhere that the specs on CD’s have evolved with time and some early decks may have problems reading more recent discs. I’ve got a deck that is unable to play any burned CD’s that can be read without problem on my BS9000.

Worth a try.

[YannChris]

Hello Beoworlders,

To Matador: I did not test a lot of CDs as I was unsure that the mix between lasers and servo boards was safe.

To all: I went further on the CD150 alternative solution and found that the grey 14 pins connector of the Beocenter’s drive is split in two separate connectors (9 + 4 pins) on the Philips one.

The last option is to send my drives to someone who is able to repair them.

Anybody interested?

Kind regards,
Yann.

[YannChris]

Hello Beoworlders,

Following Matador’s advice, I tested the still “functional” drive with several discs.

There is no logic in the results, as some CDs with a lot of tracks work fine and some don’t.

On a few of them, the discs is read for a few seconds then stops.

In one case on a short disc, the sound was highly distorted.

I suspect that tuning of the CDM2 laser is not adapted to the CDM4 servo board.

Any advice?

Kind regards,

Yann.

 

 

 

 

[Dillen]

Unless you are absolutely sure you know what you’re doing, it’s never a good idea to swap servo PCBs between lasers. Let alone across different drive versions.

Martin

[YannChris]

Hi Martin,

I completely agree with you.

That’s why I only did short tests and don’t plan to use this hybrid solution.

By chance, once the servos and lasers were paired properly, no further issues arose.

For now, I can’t go further without the help of someone in the know.

Kind regards,

Yann.

 

 

[pilatomic]

Hello YannChris,

I’m a bit late to the party, but after a close inspection of your 1st photo, the bottom right resistor looks suspicious to me.

According to the documentation I have for the CDM 2 ( not for this exact board ), this could be R3108, a 4.7 ohm resistor responsible for filtering part of the +5V rail.

Can you get a closer look ?

[YannChris]

Hello Mathieu,

Many thanks for your advice.

I do not have the CMD2 anymore, as I sent my Beocenter to be fixed by a professional.

But I still have my 2nd Beocenter’s CDM4 drive.

If you have any clue, I’m interested.

Kind regards,
Yann.

[pilatomic]

Hello Yann,

I’m afraid I am not familiar enough with these circuits to offer any meaningful clue on this issue.

I can just wish you to find someone with experience on those.

Best regards

[Author]

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