Beosound Overture CD wont spin some help

[humb11]

Hi to all in this forum.

I have in hands a B&O Overture that CD wont spin.

Have clean laser and diode.

Have made the tests with service mode.

1- test focus (i can see light with camera)
2 - off
3 - Spin clockwise (ok)
4 - Stops
5 - Moves laser (ok)

Changed caps on mech board all 6.

Any ideia????

 

[Mooly]

That looks like a CDM12.1 ? or VAM type derivative.

So the laser is lit during the time the lens performs a focus search operation (when it moves up/down 3 to 5 times) ?

Most player faults are down to the pickup so that has to be favourite really. The platter won't spin until focus on a disc is found.

 

[humb11]

It´s a 12.4 and it does lit when searching for focus.
Could it be too low the power off laser?

Its that laser that has an IC TDA1302T

 

[Mooly]

Low emission is possible, but virtually impossible to check without a laser power meter. Contaminated optics internally in the pickup can give problems too.

There's a fair chance a new pickup would fix it... and there lies a problem because the CDM12.4 has been out of production for many years and the offerings available today vary enormously in quality.

 

[humb11]

Ive consider buying a new unit, just laser.

I´ll do that an then post the result,

Thanks for the help

Cheers

 

[Mooly]

OK 🙂

I wish I could be more confident over this one and in particular the quality of replacements... but the 12.4 is favourite as failure item.

 

[humb11]

I´ve already received and mounted the new laser, know cd spin and stops.

Like he haven´t found focus.

Can´t check what could be the problem,

 

[Mooly]

In the first post you say it doesn't spin a CD.

So it sounds as though changing the pickup has changed the fault with you saying a "CD spin and stops". Is that correct ? If so then it has found focus. It wouldn't spin if not. I assume its not showing the TOC (table of contents) on the display.

What you should do is look at the RF signal from the pickup on a scope... it tells so much of what is going on in a player.

 

[seppoa]

In first post you say that in test mode 1, Focus test the laser lights. With an disc in place, you should hear the laser focusing, when nudging the disc. If so, the focus works, so next step in test mode will start the disc spinning with focus. Then you should see the RF waveform om the proper testpoint, wobbly thou as the tracking servo not is closed yet...

To properly diagnose this kind of faults you need an oscilloscope. I have access to service information at my work, I work at an authorised B&O service shop, but these are not my main workload 🙂 So if needed I can investigate more, then I need the complete typenumber in digits, not only name of the gear...

/Seppo

 

[humb11]

reference: CDM-12IND
310414702111

ON BOARD CD CONTROL
310414820181
CDM 12 B-O
PHILIPS 1995

 

[humb11]

What i´ve check is the service manual that i have the board that controls CD and adjustments are diferente, can´t find resistor that ajusts current to laser it should be on board nº8.

But there there is no resistors ajustments.

The manual says that when you change the laser that´s the first thing to do, or CD will spin and stops because exceeds 25mv.

Help in this isssue. Please

 

[humb11]

Is there anyone in this forum that could please give me some lights on this issue!!

 

[Mooly]

The laser power control preset is mounted on the PCB attached to the pickup itself (on a CDM12.4) but should never need adjustment away from the factory setting.

 

[405man]

I have repaired a conciderable number of these, about half were faulty lasers some were faulty capacitors on the control board behind the laser and a couple had faulty interface boards on the B&O unit, faultfinding is easier if you have a spare CD deck, I had spare B&O interface boards so I did not investigate further and I have a couple of faulty control boards which were not fixed by replacing the capacitors. The B&O manual assumes that you will replace the complete assembley so not very helpfull.

Stuart

 

[405man]

I should have added that in almost all cases the laser was lit and the system attempted to focus. The usual action is for the laser to return to the center then to light then find focus then read TOC then play, I did have one where the laser went to close to the center so could not find TOC, if you moved the laser out about 5mm everything worked and I adjusted the stop switch and everything was well

Stuart

 

[humb11]

Understood! I will try the second option and post results,

Many thanks for the help

 

[mzile]

Understood! I will try the second option and post results,

Many thanks for the help

Hi Humb11, how did you go with this issue? I seem to have a similar problem where, occasionally, when I load a CD, the CD spins, stops, spins again and stops again. Seems to be on and off but has been more off than on. I'm hoping it is what Stuart (405man) said, i.e. if laser goes too close to the center and cannot find TOC... I will try moving the laser out by about 5mm and see if this changes anything.

Mario.

 

[mzile]

I should have added that in almost all cases the laser was lit and the system attempted to focus. The usual action is for the laser to return to the center then to light then find focus then read TOC then play, I did have one where the laser went to close to the center so could not find TOC, if you moved the laser out about 5mm everything worked and I adjusted the stop switch and everything was well

Stuart

Hi Stuart, are you able to advise how you adjusted the stop switch? Mario.

 

[405man]

The switch is next to the disc motor and is operated by the end of the rack attached to the side of the laser, I bent the contacts forward about 2mm, make sure you bend both

Stuart

 

[mzile]

The switch is next to the disc motor and is operated by the end of the rack attached to the side of the laser, I bent the contacts forward about 2mm, make sure you bend both

Stuart

Thanks very much Stuart. Will let you know how I go. Can I ask where you are located? Mario