There seems to be some power troubles as the lights pump a bit, too. Perhaps I should try to replace the output coupling caps and the power supply cap first? And to re-solder that horrible board. The coupling caps could be a logical place to start as the problem is clearly with only one of the two channel and might be because of it's coupling cap going mad.

I am dying with projects that I never get finished and I don't want to have any more! I will try some more things but then I'd appreciate a lot if you could help.

Ville Laustela:

I am dying with projects that I never get finished and I don't want to have any more!

Me too

The lights pump a little in all of mine as well once you get any real volume going. The dial lamps are fed from a separate transformer winding so they shouldn't tell much about the rest of the power supply. But checking the power supply is probably where to begin (and that the power gets to the power amps, as well). And check those DC test voltages given in the schematic at the amp, they should tell you at once if something is abnormal there.

Can someone post a photo of the correct stereo decoder, with model number if any?

There is an old radio shop here which has stock of old B&O parts. I got a Decoder for the BM1400 from him once. I'll be happy to check for you if he has this part.

Menahem

... the mains fuse and it's holder are horribly oxidized; that might have something to do with the lights pump.

I will check around the power supply later on this weekend or next week.

Some more founds: the red wire (as seen in the photo of the horrible-looking-solderings-and-newer-black-caps is loose) both from that board, but also loose from it's other end; the AD139 transistor on the rear panel! I will do some schematics study to figure out where it should be connected....

Ville Laustela:

Some more founds: the red wire (as seen in the photo of the horrible-looking-solderings-and-newer-black-caps is loose) both from that board, but also loose from it's other end; the AD139 transistor on the rear panel! I will do some schematics study to figure out where it should be connected....

Well, then you have one half-wave missing from the output since one of the transistors is out, and it will sound distorted... measure the transistor first before reconnecting it. If it is shorted, connecting it back may burn something else.

Menahem, here are some pictures of the stereo decoder from my Beomaster 900M (type 2222-3, s/n 71669). Text "602L49C" is etched in the corner of the PCB. It has a wire pigtail of maybe 15-20 cm to the Noval plug, and one transistor hanging loose (it switches the stereo indicator bulb, and is supposed to be screwed into the frame for cooling).

tournedos:

Well, then you have one half-wave missing from the output since one of the transistors is out, and it will sound distorted... measure the transistor first before reconnecting it. If it is shorted, connecting it back may burn something else.

I actually already reconnected it; nothing exploded.

The wire was clearly just broken from the solderings from both ends.

I am just about to try with speakers again....

I have now assembled the Stereomaster again and connected the internal speakers: it sounds like it worked!  I am now running some tracks in thrue tape input and radio and I think it really works now. So the problem was simply a loose wire of the transistor. I also replaced the black caps (originally one cap of 64 uF 25v) and remade some of the ugliest solderings. 

One other thing I noted is that the right-side speaker element is of different type. I was wondering why the right side speaker cloth was higher (see the first photo on the first page of this thread) than the other; the replacement speaker is bigger than the original (I believe the left one was original). Martin (or somebody else), would you happen to have one of those?

I will start cleaning the front panel and later on I will do something for the woodworks, too.

Thanks for the tips; I am really happy to get this going again. I will send some more photos as soon as I get the Stereomaster out of my desk...

Excellent, congratulations!

When cleaning the front panel, be careful not to rub the markings off if you have to clean on the inside as well. They look like they can't take any kind of solvent.

Regarding the woodwork, I used no. 600 wet sanding paper on mine (obviously dry, and with a sanding block). Careful at the edges so you don't rip the veneer of the perpendicular surfaces off. After the surface was smooth, I cleaned off any dust with a damp cloth, and then applied teak oil several times. Worked wonders, I managed to remove even some deep scratches and flower pot marks from the top. Watch the thickness of the veneer so you don't sand through it - it's hard to say if it will be thicker or thinner in this Finnish version.

Thanks!

I first tried carefully if the markings seem to be loose but they were firmly in place so I cleaned the whole panel from both sides. There are several bigger scracthes and even some rust in the lower panel so it can't be made mint but it will be fine. I didn't have any good sanding paper at hand so I just applied some bee-wax to the top and it looks a bit better already. There are some deep scratches that will most likely stay there but good sanding will make it look better. 

This really sounds great; even though not quite balanced as the speakers are of different type.

And yes; if I can get a stereo decoder somewhere I would be delighted!

Attached are some more photos (yes; I am keen on taking all kinds of glowing-in-the-dark photos)

The right-hand-side speaker. Someone has replaced it someday in the past. I might replace it with an original type if I can get one.

The woodworks after slight cleaning and some bee-wax on the top.

Nice glow in the dark...

The knobs are on the right corner; I was cleaning them while taking this photo.

Another view...

And one more.

The Stereomaster is now back in one piece and ready to go for action. I am not yet sure where I will put this (I might take this to work) but I will get it to be used somewhere. Looks great and sounds, too.

Stereo decoder and original speaker - if someone has / gets one; I am interested!!

Thanks for the tips and attached are some (more!) photos of the Stereomaster.

It's fun to discuss and send posts with myself...

Today I received a Beomaster 1000 (the older model with white keys and scale) for a quick repair (burnt lights on the scale and missing tuner pointer (!!!!!!!)). I noted that it had a very similar stereo decoder and I tested the Stereomaster with it. Works great! The Stereomaster decoder is fastened in a bit different way so I couldn't test with the internal speakers but with external ones it sounded just wonderful and it was indeed in Stereo. 

So this type of decoder works, too. (To use one in 900/Stereomaster would require some modification with the installation but nothing too serious). 

Just because we're quiet, doesn't mean we aren't listening.

Nice photos and it's a nice set.

Martin

Indeed!

That stereo decoder seems to be exactly the same as in my 900M, only it has a mounting bracket / cooling fin combo, whereas mine is just soldered in the same "hinge" that holds the power amp board.

I actually like the look of the speaker cloth more than the hard plastic grilles on the "real" 900K. Otherwise, the case looks a bit heavy though. Wonder how many of these were built?

The mounting bracket of the 1000's decoder didn't really fit into the Stereomaster so I had "a bit" temporary and impractical installation....  

This is why I had to test with external speakers! With a bit of modification the 1000 decoder could be fitted there, I guess.

I have never seen a B&O 900K but from the photos I have seen I'd say I prefer the Helvar version. The speaker cloth give it a nice lighter appear and the fact the cloths are slightly deeper in the facia makes it to look very nice.

         I have seen now two Stereomasters but I have no idea how many of them were made or are still alive. I could try and send an email to the Helvar (nowadays they make light controllers etc. but they just might have some records still available) and ask about the B&O cooperation - that might give some idea.

I agree with Martin.
We are watching this thread with great interest.
May I say how nice it is to see someone of your age working on this type of equipment, down to component level.

Andy T.

There were other producers of MPX modules (stereo decoders) that fit
the Beomaster 900 and 1000.
Just recently, I discovered this Scan-Dyna module in a Beomaster 900K.
Same method of fitting and same plug as B&O's.
Not sure if that will make it much easier to find one, though...

Martin

... and the reverse side:

Got the pics!

When I'm in Tel Aviv the next time (we live in a village about 3 hours away), I'll go in and see if he has one in stock.

Menahem

Thanks for the photos, Martin.

I would be most glad if any one of you would find a decoder for me!

When I bought my 'Wyndham' Beomaster 900K, it too had a missing decoder board, and some missing knobs.  Frede came to the rescue and was able to supply the decoder board and the knobs, and a RIAA preamp board for my Beogram 1000, which is a natural partner for the 900K.  I'd suggest contacting him.  Good luck, and thanks for the write-up - it's a good looking set and It's great that it is being restored and used.

No luck for the Stereo Decoder at the B&O parts depot in Tel Aviv.

But check this parts unit on ebay - says that the Stereo light works!

380173367669

Also some other good vintage stuff, and Danish L&L tube stuff!!!

Menahem

Hi Menahem. Thanks for checking.

After the last post I have bought a working stereo decoder from Frede (thanks again!) and it's now installed and working. Sorry for not mentioning it here.

The Stereomaster is not in use at the moment, but safely in storage waiting for a proper time and place. (I am at work now, and have a complete 5000 system here. I have it for repair and as I don't have space for it at home I have it at work.  BC needs belts and other small things, Martin's parts should be here today/tomorrow. )

I was just informed that Helvar-Celeston, the finnish company, had a quite intensive cooperation
with Bang & Olufsen from 1962-68.
Several of B&O's models were produced in Finland under the Helvar-Celeston brand.
The Stereomaster (Beomaster 900K) of this thread being one of them.

Basically, the Helvar-Celeston models were more or less identical to the
ones B&O produced in Denmark but with other dials, logos, lettering etc. and
sometimes with slightly different component suppliers.
Some of the portable radios were among the models, they were sold under names like
Celeston Marita (Beolit Teena),
Celeston Rita (Beolit 608/609)
Celeston Rita Automatic (Beolit 700)
Celeston Trans 14 Export (Radio BEO)
etc.

Martin

Dillen:

Some of the portable radios were among the models, they were sold under names like
Celeston Marita (Beolit Teena),

There was one of these for sale last winter in a local auction. Silly me, I didn't grab the picture, but it looked exactly like the Teena except for the script of course. I've also seen one of the local BEO / 610's.