Stereodecoder for Minette 609/610K and Dirigent 609/610K

Hi Beoworld,

I have few questions regarding two vintage B&O devices. It is about Minette 609K and Dirigent 609K. I bought both devices some time ago and few weeks ago my good friend and technician Robert got them on his workbench to check/clean and repair them (few little issues on both). They are now fine, works very good but I don’t like one thing about them: unfortunately both devices are without Stereodecoder :-(

I decided to try to find at least some information about those optional boards and if possible to find and buy them. I know that those are very rare and that it would not be easy to find one.

There were few threads on Beoworld about similar issue but actually I didn’t find any concrete information, pictures or schematics. I know that the stereodecoder for Minette 609/610K was unique. It has a Type number 8902017 (thanks Martin for that info). The second one build in Dirigent 609/610K is different.

So the first question is: Is there any similarity of this decoder with oder stereodecoders built in other devices of this era (Master de Luxe / Grand Prix 608/609/610)?

I am looking for the original schematics. I would be very thankful for few pictures in good resolution from inside of devices (if possible from both sides of the printed board).

So, is there any chance that one of you has a schematic and is willing to share it with us/me?

I would appreciate any help on this issue!

Thanks.

Mika fitted a stereo decoder to a Dirigent a couple of years ago.
It must be in the archived forum somewhere.

Martin

Hi Martin,

thx for that information but I can not find it. I found only this thread from Frede. There are some interesting information (actually more questions as answers) but no pictures or schematics.

Can you post the old Mila's thread ?

Or maybe he is around and can help too....

BR

 

My old thread on my Dirigent 610K is here in the archives but it seems I didn't post much on the stereo decoder.

Anyway, I quickly gave up on the idea of ever finding an original decoder or even building one from scratch, as I'm not too interested in trying to replicate the coil tanks and other funny components.

I found a web page where some guy from Germany had fitted a Kemo B127 stereo decoder kit into an old Braun valve receiver. That proved quite promising as the signal levels of the kit are almost directly compatible with the circuitry of the Dirigent (unlike with a BM900 for example, where you would need additional amplifier stages). Some coupling caps on the decoder will need to be replaced.

It's far from plug and play though - while the Dirigent is supposedly "stereo ready", it needs a number of modifications in the IF and detector stages. The original mono circuitry will pass the 19 kHz pilot signal and light the stereo lamp of the decoder, but the bandwidth isn't nearly enough for the stereo matrix signal riding on the 38 kHz subcarrier, so you get very little or no channel separation. Even 50 years ago, the technician installing the original decoder would've had to do the same modifications.

Also, you will not find the supply power for the kit in the Dirigent. Thankfully it consumes very little power, so I was able to steal it from the valve heater supply without a transformer or directly grounding either end of the heaters (two-ended AC through two caps, then rectified to feed a 78L regulator).

It seems you can still find the Kemo kit for peanuts on the interwebs, although the IC it uses was apparently obsoleted a long time ago.

Here's the final installation - right where the original would've been. The LED glows through the vent holes on the cover and the sound quality is extremely pleasing

Most of my notes seem to be in the magical Somewhere land since I've moved after this, however, here are the schematics of the interfacing and modifications.

It could use some tweaking of the resistor values that interface the Dirigent detector output with the AF input of the Kemo decoder. With these values, the audio levels of mono and stereo mode (seleted by the rotary switch on the front panel) match well, but it loads the detector output a bit too much and the tuning indicator (EM87 valve) doesn't quite reach the top of its usable range.

Hi Mika,

many, many thanks for your help! Your description is superb and very detailed.

I thought too that it will be very difficult to find the original decoder and I thought we could build one from scratch. To make the modification of existing decoder you wrote about is probably the best way though also not easy. But if I don't want to wait years for the original one...

@Leslie & Co. Any chance that somewhere in your dungeons one unused stereodecoder is sitting useless around?

Now I will look on Bay or other Internet and local opportunities to get one.

Once again many thanks.

I will post news about this project as soon we have some.

Regards,

Theomaster

 

Martin
(Scan by PerH)

The 890001 decoder shown in this thread http://archivedforum2.beoworld.org/forums/t/12546.aspx
is in the repairshop "bulk" packing (grey box).
Like this Type 2015 :

Identical to the one fitted in this Grand Prix 609 http://archivedarchivedforum2.beoworld.org/forums/p/28435/224654.aspx

 

On the shop-shelves, you would find the 890001 in a more visually friendly blister packing like this:

Martin

Martin, you are simpy grate!

How do you find all those pictures?!?!?

I know, the way I make my questions and answers to my own and other posts is not always realy inspired but you are always ready to be challenged ...

Cheers for that!

Grate to have you here.

 

the_o_master:

How do you find all those pictures?!?!?

I didn't find them.
I took them a couple of minutes ago.

Martin

I have a couple of info's of the SD 610 for you.

/Frede

.... and 1 more

/Frede

SD610 implemented in Dirigent.

This give you a chance to practice your Danish ......

/Frede

 

Dillen:

I didn't find them.
I took them a couple of minutes ago.

Martin

O my goodness, how deep and big could your Beo-dungeon be, with all that treasure

 

classic:

SD610 implemented in Dirigent.

This give you a chance to practice your Danish ......

/Frede

Also many thanks to you Frede!

With those schematics we could really try to make it from scratch too.

And Danish is bit complicated but with google-translate not impossible

Send me a PM and I can send you the PDF file with all information.

/Frede

OK, we started the preparation of the project "Stereodecoder 609/610"

The PCB and standard components would not be the problem.

The big issue will be to find ***.
So, we are looking for following parts:

***

We also need the ***.

A *** would be also helpful because we hope we could then clone few pieces.

So, if anybody can provide any of these components or maybe has **** , it would be grate help for us.

I count on you Martin, Frede, Mika ....

Best regards

 

 

*** EDIT by Dillen

Sorry, I had to edit your post. 
A minimum membership level of silver is asked for to place sales/wanted ads.

Martin

Dillen:

Sorry, I had to edit your post.
A minimum membership level of silver is asked for to place sales/wanted ads.

Martin

Hallo Martin,

thank you for "remind me".

I renewed my silver membership few minutes ago.

So I hope now I may ask what I want. Here my second try:

OK, we started the preparation of the project "Stereodecoder 609/610".

The PCB and standard components would not be the problem.  The big issue will be to find those filters. So, we are looking for following parts:

Coils (DE:Filterspulen) for Stereodecoder: 993 L 151 (19kHz),  993 L 152 (19kHz), 993 L 153 (38kHz). The numbers are taken from schematics.

We also need the ZF-Filter for my Dirigent: 971 H 172, 971 H 173,  971 H 174 und 971 H 175.

A single component would be also helpful because we hope we could then clone few pieces.

If anybody can provide any of these components or maybe has spare parts PCB, faulty Dirigent (or Minette), it would be grate help for us.

Best regards

Hi Frede

har du på nogen måde en indbygningsvejledning til Minette FM 609K. Jeg kan se at der er mange ligheder mellem Dirigenten og Minetten, iden der vel aprimært er LF amp’en til forskel.

Sagen er at jeg har hittet enb stereodekoder fra en BM 1000, og vil bygge den ind i en Minette. Det ser ud til at kunne lade sig gøre, men i din beskrivelse af Dirigenten indgår der et ekstraprint som jeg ikke kender omfanget eller indholdet af. Det skal sikkert opbygges separat, men først når jeg ved hvad det indeholder, og hvor det skal monteres.

Kan du hjælpe?

På forhånd tak

mvh

Flemming Hynkemejer