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Beosound 9000 MK I skips tracks after a while

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JoDap
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JoDap posted on Sat, Oct 31 2015 1:23 PM

Hi,

I am newly registered here, after having read in the forum for a while. So I hope that I got the right subforum for my question.

The problem with my BS9000 MK I is not unique as I see it, and there have been numerous threads about this before, and I also read them. However, I'm a bit confused now:

1. I learned that there are at least two different CD mechanisms that were used for the BS9000. The CDM 12.4 and the VAM 1250, both Philips. Most threads about this topic are about MK III and they regularly mention the VAM 1250, so I assume, that mine would be originally fitted with a CDM 12.4, is that right?

2. I read that in most cases the CD wouldn't turn, or the player would go to Pause immediately. In my case the player works fine for a while (up to about 45 min) and then starts skipping. The skipping gets worse over time and eventually it says PAUSE and turns off shortly after. Can this still be attributed to the same error?

 

About two years ago, after moving, I had the same problem and brought the unit to a B&O shop. They replaced the complete laser unit and everything worked fine there. I think the price was around 400€, but the glass lid was also loose back then, so I don't know how much the laser repair alone would have cost.

In the meantime I moved to another country again, so it is difficult to go back to that shop. Anyway, I asked a dealer here and they estimated that if it is the laser unit they can repair it for about 400-450 €. Since that is quite a lot of money to spend (again) I took the player apart and asked a colleague (electronic engineer, works professionally with laser systems) to have a look at it because he suspected that it might be a cold joint at the laser diode. The first thing I noticed was that the unit is a VAM 1250, which surprised me. Secondly, the type label doesn't have the Philips logo. Is that normal?

The engineer found that everything is in order with the solder joints next to the diode. We didn't open the unit to see if there is something else, but he suggested turning the potentiometer a little to increase the power. I DID NOT DO THAT YET.

I assembled the entire thing again and the behaviour has (unsurprisingly) not changed. I checked testmode 27 and it says CD ERR. 03, which according to the service manual of an MK III means: Radial Error; Set when the CD did not get on track after several retries.

 

As far as I see it, my options are the following now:

1. Get it repaired at the B&O dealer

2. Try to find a VAM 1250 pickup or entire unit and put it in myself (I am capable of doing that)

3. Put a CDM 12.4 unit in, since they seem to be more accessible. Question is: do I need to change the PCB as well?

 

Can someone please help me around my confusion about the different mechanisms and suggest what I should do next?

Cheers!

 

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JoDap
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Answered (Verified) JoDap replied on Tue, Nov 3 2015 10:26 PM
Verified by JoDap

Hi, 

I took it apart today and had a very close look at the mechanism, but everything looks fine there. I then drove the sledge all the way out by applying 5V to the small dc motor and it moved without a hitch. I left the sledge there (outermost position) and assembled the whole thing again (I'm getting fast at that Smile  ) 

After powering up the player, the laser moves to the home position and testmode 65 only moves it out. However, Itried playing tracks on outer positions of the CD and it works fine. All evening now with only one little hickup (could also be something with the disc). 

So it works again and I don'treally know why. Magic perhaps...Anyway, the testmode for "light pen out" is still not clear to me. Is it supposed to move the pen only halfway out? Would be great if someone  could confirm that. Otherwise I'm happy, obviously Smile

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JoDap
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JoDap replied on Sun, Nov 1 2015 7:34 PM

Hi again,

I have a short update:

Today I investigated the matter a bit more systematically and I found that the skipping is not dependent on time, but on position of the laser head. I.e. always around tracks 8 - 10 the problem starts. I tried with different CD's obviously. I also took the mechanism out and checked if everything moves smoothly, but it looks alright. When I try Testmode 65 without CD, it looks like the lens moves only about halfway out. I can try to make a picture of that, but it is very difficult to see.

Has anyone observed such behaviour before? What can be the reason for this?

 

marexy
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marexy replied on Mon, Nov 2 2015 12:11 PM

Hi

BS 9000 MK1 has 2 different CD machanism- laser head ( CDM 12.4 and 12.6 )

usuly  typ 2621 - cdm 12.6   and    typ 2626 - CDM 12.4

do not switch them!

 

JoDap
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JoDap replied on Mon, Nov 2 2015 7:57 PM

Hi,

Thanks for your reply. That was also what I thought, but this is the actual unit inside my BS 9000 (type 2621)

I have also another picture here that shows the position of the light pen when it is supposed to be all the way out:

Beobuddy
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I would start by taking the complete lasermechanism apart. take out the pickup unit and clean the whole machanism and grease them lightly. Carefull with the spring at the side of the pickup when you reassemble the parts.

Every different laser has its own PCB. The VAM 1250 and VAM1255 can still be ordered or replaced by the dealer.

JoDap
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Answered (Verified) JoDap replied on Tue, Nov 3 2015 10:26 PM
Verified by JoDap

Hi, 

I took it apart today and had a very close look at the mechanism, but everything looks fine there. I then drove the sledge all the way out by applying 5V to the small dc motor and it moved without a hitch. I left the sledge there (outermost position) and assembled the whole thing again (I'm getting fast at that Smile  ) 

After powering up the player, the laser moves to the home position and testmode 65 only moves it out. However, Itried playing tracks on outer positions of the CD and it works fine. All evening now with only one little hickup (could also be something with the disc). 

So it works again and I don'treally know why. Magic perhaps...Anyway, the testmode for "light pen out" is still not clear to me. Is it supposed to move the pen only halfway out? Would be great if someone  could confirm that. Otherwise I'm happy, obviously Smile

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