[KolfMAKER]

Thank you, that is a very important additional test.

If I understand correctly:

– BCK remains OK
– WS remains OK
– DATA remains OK
– VDDA / VDDD / VDDO remain stable at 5V
– MSUB remains at 5V
– and the analog audio signal disappears directly at the output pins of the TDA1305T

Then I agree: this makes the TDA1305T itself the most likely cause.

At this point the problem is probably not the CD mechanism, not the digital signal going into the DAC, not the supply voltage and not the mute line.

The difficult part is finding a trustworthy replacement. Since the TDA1305T is an old Philips/NXP DAC, I would be very careful with Ebay or AliExpress parts. They may be reclaimed, relabelled or fake, even if they look correct.

I would try:
– NXP authorized distributor network
– Rochester Electronics
– professional obsolete component suppliers with traceability
– or possibly a donor board from another known-working unit

Personally, I would avoid buying more “new and original” ICs from unknown marketplace sellers unless they can provide proper traceability.

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Thank you, that is useful information.

If BCK, WS and DATA remain OK, and VDDA / VDDD / VDDO all remain stable at 5V before and after the audio disappears, then the digital input signals and supply voltages to the TDA1305T seem to be present.

That does make the DAC a stronger suspect than before.

However, I think there is still one very important measurement missing:

Is the analog audio signal still present directly at the output pins of the TDA1305T after the sound disappears?

If the analog output from the DAC disappears while BCK / WS / DATA and all 5V supplies remain OK, then I would agree that the DAC itself becomes very likely.

But if the analog signal is still present at the DAC output pins, then the problem must be after the DAC, for example in the muting circuit, output stage or coupling components.

So in my opinion the next decisive test is to check the analog output directly on the DAC pins before and after the fault occurs.

Let me know the outcome!

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Thank you, this clarification is useful. What I now think is:

The fact that the original IC always returns to exactly the original behaviour probably means:
– the board itself was not permanently damaged during the IC replacements,
– the original fault is still present in the same signal chain,
– and the Ebay IC’s may indeed be questionable, but they still do not automatically prove that the original DAC IC is the root cause.

The 3 different behaviours with the 3 IC’s are interesting:
– original IC → sound disappears after 1-2 minutes,
– replacement IC #1 → intermittent sound after ~30 seconds, then mute,
– replacement IC #2 → no sound at all.

This could mean:
– the replacement IC’s are fake / reclaimed / defective,
– or they are more sensitive to an existing surrounding circuit problem.

At this point, I personally would not continue buying more TDA1305T IC’s before doing more measurements around the original IC.

I think the important next diagnostic step is determining:
Does the audio already disappear directly at the analog output pins of the DAC, or only later in the muting/output stage?

That would help confirm whether the DAC itself is really failing.

I would suggest checking:
– DAC supply voltages before and after audio disappears,
– BCK / LRCK / DATA signals,
– mute line / muting circuit,
– analog output directly on the DAC pins,
– freeze spray / thermal testing on the DAC and surrounding components.

To me this still feels more like a surrounding circuit or thermal issue than a confirmed pure DAC failure.

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Thank you, that information helps.

Since it is a MK3, at least we know the technician is working with the correct service manual and the correct DAC type (TDA1305T).

However, the behaviour still does not fully convince me that the DAC IC itself is the primary problem.

The fact that:

• the CD continues spinning correctly,
• timing continues normally,
• and the audio first becomes intermittent before disappearing,

still sounds more like a thermal or surrounding circuit issue to me.

Possible areas worth checking:

• power supply stability around the DAC/audio section,
• voltage regulators,
• electrolytic capacitors,
• mute circuit/transistors,
• solder joints or hairline cracks,
• temperature-sensitive components around the DAC stage.

Especially because the failure develops after some operating time.

A useful diagnostic step could be freeze spray / controlled heat testing around the DAC and surrounding circuitry to see if the behaviour changes immediately.

Questions

1. Does the sound always disappear after roughly the same amount of time?
2. And does it return again after the unit cools down?

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

I am not fully convinced yet that the TDA1305T itself is the root cause.

The fact that the CD keeps spinning and timing continues, while only the audio disappears after 1-2 minutes, could also point to a thermal issue, power supply instability, muting circuit, soldering problem or an issue around the DAC/output stage.

Also, the different behaviour with the replacement IC’s does not automatically prove they are fake.

One important question:
Which version of the Beosound 9000 is this exactly? MK1, MK2 or MK3?

There are differences between revisions/boards and that may matter here.

Do you know:
– the exact type / MK version?
– whether the service manual matches this unit?
– if the supply voltages around the DAC were measured when the sound disappears?
– if the mute signal changes state when the audio drops out?

To me this still sounds more like a surrounding circuit issue than a pure DAC failure.

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

@Adams

Thank you very much for sharing your experience. I haven’t had the opportunity to compare all the BeoGram models, and experience their differences.

So, this information is welcome!

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

@Adams

Interesting comment.

How would you rate the BeoGram 4000 series, compared to other (later) linear tracking turntables, and radial tracking turntables?

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

A warm welcome to you Michael !

Great you got the virus too. And by the way, your story brings back to me the ‘triangle of top designers’.

• Braun design s became famous because of (the great) Dieter Rams.
• Apple’s top designer Jonathan Ivy was inspired by the designs of Dieter Rams. There’s a famous list of Apple products derived from Dieter Rams’ / Braun designs: https://sl1nk.com/fVgIa
• Jonathan Ivy also was inspired by the B&O designs, especially with aluminum, which is obviously recognisable in most Apple products.

So, going from loving Braun to loving B&O is quite logical. Enjoy it!

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Dear Daphne,

I get that.
Your Beolab 8000’s were manufactured in 2002.
With this serial number, they are MK1. (serial number 1699 2475 and above are MK2)

Best,

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

I took my BeoGram 1000 out of storage to check how my platter gets disassembled.

With my BeoGram 1000 it’s a 2 step:

1. Remove the C-clip to remove the inner (plastic) plate with the strobe markings.
2. Remove 3 screws on the main plate, to lift it from it’s holder (see the 2 pictures).

In your case, the 3 screws are rivets. So lifting the platter won’t work the way it does for me.

Though:

• If you need to check the suspension, the platter doesn’t have to be removed. For suspension you need to get the acces via the bottom of the plinth.
• If you need to replace the driving belt, there are ways (not the easiest ones) to do that with the platter in its normal position (for instance as described here after point 11)
• If you need to get the platter out of its way: since it seems to be attached to an assembly including the platter axes, there should be a way to release this axes from the shaft. But this can only be done from the bottom side.

 

 

 

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Are you able to rotate the platter, or is it stuck?

For your information, the platter you are trying to remove, looks like this from the bottom side:

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

If I remember well, you should be able to lift the platter up/out.

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

I had the same the first time. But look very closely.

There is a C-clip that sits on the axel-pin in the middle (seen from the top). Remove that, but be careful that it doesn’t jump away.

When removed, you can lift the inner disc with the strobe markings.

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Interestingly, the item on eBay mentions ‘VAM1250/21′ and the main picture shows the exact same box (and VAM1250’ on the white sticker on the box) as the unit I got from Keith Saunders.

If I would have to get one now, I would try this.

(I am not guaranteeing for you, it’s always your own risk)

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Very sorry to hear the VAM1254 does not work.

Though, even if they look almost the same, they are not. I read a lot of info about OPU’s. The VAM1250/21 that you need belongs to the ‘CDM-12 Pro’ family of OPU’s. Others are: VAM1204, VAM1205, VAM1206, VAM1252 and VAM1254. They all share comparable specifications, which also means there are differences. Unfortunately, you just found out about that.

The OPU you have in your BeoSound is a VAM1250/21, like I had. I was lucky to find one with the help of Keith Saunders. Although it is a VAM1250 (not /21), I know this one works.

You can try to contact Keith, but if I remember weel, he sent his last unit to me.

I made a quick check on eBay and found this one: https://www.ebay.com/itm/363230316872

It is a VAM1250, but I don’t know how reliable the advertisement/advertiser is. Maybe you can try to contact them.

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Thanks for adding the picture. It confirms that your laser unit (in the MK2) is exactly the same, as mine (in a MK3).

This type is a little bit hard to find. I made a picture of the packaging on my replacement laser unit (see below). It does not contain any manufacturer/supplier specific text unfortunately. ( The Chinese characters mean ‘Chinese New Year’s Eve) And the barcode number is not leading to specific and right product or manufacturer information.

Though, the looks of the packaging might help you to find the right laser unit.

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Hi Igor,

Can you share a picture of the sticker you refer to?

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Fortunately, I was able to find a VAM 1250 through one of our respected members in the BeoWorld community: Keith Saunders (many thanks to him).

Also I got the laser unit with original packaging. And I think I remember that packaging from a Chinese manufacturers webshop page.
When I have time I will go check that again, because I guess there will be more people in need of this type of laser unit.

Best regards,

 

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

Where can I find it Frog?

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[KolfMAKER]

In the meantime I did find a VAM1250 at Dõnberg Electronics in Ireland:

https://www.donberg.co.uk/catalogue/vam_1250.html

But it doesn’t have the addition ‘/21’. So, I am not sure if this is the right one (Dönberg also doesn’t know if it will work.

 

Question

1. Does anyone know if this VAM1250 will work in the BeoSound 9000 MK3?
2. Are there any other laser units that are compatible with the VAM1250/21?

 

The VAM1250 at Dönberg Electronics:

Location: The Netherlands

Favourite Product: BeoSound 9000

My B&O Icons:

[Author]

Posts