Just got myself a Beogram 42VF. Not working, dirty, rusted - looks like it's going to be a full restoration.

First off, does someone have the schematics or a service manual? Somebody messed up the connections to the preamp and bypassed it.

Is there a lid? Never saw a picture of 42 with one, so I guess not?

Was this designed as part of a system - if so, which amp should accompany it? The Dirigent? I really like the colour scheme of this and as I always wanted a valve amp anyways...

Wow, a post about vintage stuff.
Nice ! 

That's a wonderful deck.
Most of these have an envelope with the schematics etc. glued to the inside of the bottom plate.
I suppose you already checked that so here is a bit of info:

The little board shown on the left is a blind-plate to fit if the RIAA is unplugged. It would have been the
correct way of bypassing the RIAA.
If the above info is not enough ask me again and I'll dig around a bit more. I'm sure I have more.

The dustcover was optional (and rare).

Yes, a Dirigent would be a perfect match and then a pair of Type M (as minimum), S or even K speakers.
Add an open reel deck and you will have a very fine setup.

For those who don't know what a 42VF looks like, here's one (Type S274):

Martin

Thanks! Now I know which cable needs to go where. The envelope is still there, but the schematics are gone.

I'm glad they bypassed it this way and didn't just junk the preamp. Unfortunately the needle didn't survive shipping, I'll have to get a spare one before I can test if the preamp actually works.

I will repaint the baseplate - looks really bad right now. Rusty spots and scratches everwhere. Also, the veneer has been painted a long time ago. Will take some time until it looks as nice as the one on your picture. But - the motor runs great! Quiet and with the right speed.

Doesn't the Dirigent already have a preamp integrated? I actually already have a open reel deck that fits the Beogram rather nice size & veneerwise (Tandberg series 15). Now where to get a Dirigent…

Is the tonearm the same as in the 1000 (except for the cueing)? Mine is rather messed up and I guess it'll be easier to find a spare...

The gyro bearing is rather wonky and the grub screw that holds the inner bearing in place is rusted shut. And I might just have ruined the screw head and any chance to get it out...  

Now, what about some pics, we love that, the Dirigent you should be able to find on Danish sites, here one, Lauritz another. Check there frequently, I have seen a pair or 2 within the last year.

For the Grub screw, soke over night in WD 40 or other rust loosener (Caramba, 3 in one), before trying to loosening the screw, try to knock it lightly more times with a screwdriver and a small hammer.

Søren Mexico:

Now, what about some pics, we love that

Alright...try and find all the parts. I'm not really into tidy workspaces. (Other things you see in the pic: a Beolab 1700 and several parts of my SAAB - yes, that thing on the floor is a power steering unit )

Baseplate de-rusted and ready for a new coat of paint.

Body before and after (sanding and wood oil). By the way, this is solid wood and not just veneer!

 

I had the screw soaked in rust loosener overnight. Unfortunately that didn't help at all. The screw head completely disintegrated…

Well…the last time I saw a Dirigent for sale on dba it was in flawless working condition. I'd actually prefer a non-working one (for a cheaper price, of course).

Edit: Just got a mail from the seller. He has a spare SP6-7 and will send it to me. Another problem solved.

Might repair the other pickup anyway - I guess a new diamond should sound better than a 50 year old. By the way, what do you use to play 78s with this? Did B&O offer a different pickup?

Good work. I have one of these too. Lovely looking decks. Mine is really in mint condition except for where the original owner stuck one of those awful "dustbug" dust removal things. This caused the rusting on the top plate. I have the user manual with mine (I will scan it for the site) and it doesnt mention anything about a lid for the deck.

Here is mine.

 

Just opened mine up and heres a scan of the schematics. The preamp bit isnt on this scan but if you need it let me know.

Martin, you say type no. S274, mine says S402. Any ideas?

 

Having just seen the picture, I'm not sure if you can read any of it anyway. If you want a better copy, let me know and I will try and sort it out.

Ablaumeise, Good work, i'm looking forward to see more of your restoration work.

Thanks a lot Beaker your SP 8-9 arrived safely. The stylus is in perfect original condition. ;)

Cheers!

Glad you like it. Are you going to use it or just look at it?

So…I'm gonna need another tonearm. Better don't ask.

What's the exact difference between the ST/M and the ST/L? Just the length?

Beaker, thanks for your scan. I don't know yet if I'll need a scan of the preamp schematics. Depends on wether or not it works...

At the moment i just look at it! ;)

Well…that was a bad idea. Just started working on the BG again, finally got the matching paint and repainted the baseplate. Problem: Turns out if you travel the world for two months and come back you might not remember what goes where. And I didn't take pictures. Ha.

Umm…Beaker? Or somebody else who owns a 42? Could you please take a picture of the innards? Just with the bottom plate off. I have no idea as to how to route the cables or where exactly the voltage selector was located before...

Here you go. Anything else you need, just let me know.

Thanks! I now reassembled everything the way it should be.

Well...so close, and yet something rather important is still missing.

Thanks to Martin, there finally is some progress:

For future reference: The bearing on the ST/L and the Beogram 1000 tonearm is identical, the arm itselft is not (the ST/L arm is longer due to the different counterweight). So...bearing replaced, adjusted - speed is perfect, tracking weight is perfect, arm perfectly adjusted...put a LP on there, take the cover off of the SP7, lower the cueing lever - I can hear the faint sound of Fehlfarben's "Hier und Jetzt" emitting from the stylus, turn up the receiver...

Guess what...I've found the reason why the preamp was disconnected.   It produces nothing but a faint hum. Let's see what we can do about that...

Does anyone have a good quality scan of the preamp-schematics? I can't really read most of the things on beaker's scan.

What I've found so far: AC126...wasn't it those that grow crystals or something?...both test ok, but the breakdown voltages measure about 0,15V on both transistors, whereas on the other two (2Nsomethings) it's the usual Germanium 0,3V. Also, one of the two diodes is open circuit. Can I replace this with a standard 1N4001 or is a Ge-Diode required?

ablaumeise:

the breakdown voltages measure about 0,15V on both transistors

I have some AC151r's that should be a replacement for both the AC126 and the AC107 (as far as I can read beaker's schematic)

They have 180mV measured on B-C and B-E so the 0.15V aren't too bad.

And looking at the supply it shouldn't be a big deal using 1N400x or even 1N4148's as there are 12.5Volts AC so .4V difference won't lower them too much. And the OA85 had 50mA only...  but change both diodes anyway.

As far as I can see this is a voltage doubler circuit - I would expect some 20 Volts supply after the different RC-stages.

Probably the bipolar electrolytics?

  hx (still lovin' his BL4500's )

The diodes seem just rectifiers for the power supply, I'm sure 1N400x:s or similar silicon diodes will do.

I think it was the AF11x types that are most likely to grow internal whiskers... but all germanium transistors are rather fragile by today's standards. Anyway if they work, I'd leave them alone; the exact measurements can vary a lot.

Thanks for your input!

Replaced the diodes with 1N4001s - still nothing. Checked the capacitors - capacitance and ESR both measure out fine.

Checked the transistors out of circuit - they also measure 1,7V e->c...they shouldn't do that, should they?

ablaumeise:

they also measure 1,7V e->c

Did you leave the base floating? 0.1V are easily catched when left open and then they trigger the transistor - even with the voltmeter only.

(Was learning by doing for myself too - my germanium days are way back now...  Anyone remembers the black OC something's?)

Ground the base while measuring & check again.

Are the 20 volts ok? I found the diagram for a BG1000 with a little different schematic: From 14VAC they create 33.5V DC after the 2 diodes, 28.5V at the first cap and 16V at the 2nd cap. But there are different transistors, both already silicium. EDIT: oops, I meant silicon

   hx

P.S. did it work without the preamp, using the short circuit plate? (yet another EDIT: just read there never was a short circuit plate - should say "did it work while bypassed"...)

When the base is grounded, it oscillates between 1,7V and no connectivity. Excuse my ignorance, I was born long after the days of germanium semiconductors.

There are 25V after the diode, I haven't measured further down the line yet.

Just bypassed the preamp, and yes, it works fine. Just a bit too quiet, if you know what I mean.

Strange. I checked the connectors, the caps, the transistors, the diodes, visually checked for bad solder joints...and yet this thing is dead as a doornail.

I'll have another look at it tomorrow, I've used up my patience for today.

You know how sometimes you spend an eternity looking for a problem, and then suddenly you stop and think: "Wait, have I checked...? I mean it's obvious, I'm sure I have...right?". Well, then you know how I feel right now.

I was measuring the supply voltage to the amps. You know, the voltage behind the power supply section. The voltmeter showed -50V. That can't be right. I mean, the minus. So I stopped and considered "in relation to what?". Well, I had it connected to the black cable of the AC supply. Which, according to the diagram, should be connected to common ground. However, there was no voltage at all in relation to the chassis. So I checked the preamp board. No connectivity between the AC input and ground. And that's when it dawned on me. The connection was not on the board, but between the connectors. Remember - those connectors that somebody had messed up to bypass the preamp?  Sure enough, there was no connection. That's when I started to feel like an idiot.  So I soldered a piece of wire on there, connected the turntable to the amp, set down the needle...music. Not sure if I should feel happy or ashamed.

No need to be ashamed, you fond the failure and thats it, I've done a lot of works where I looked for failures for days, and not finding them, stopped took a long brake, and went back to the basics.

Good job !

Repairs to faults that has no "natural" cause are often the worst and most time consuming.
Particularly if you are not aware that somebody has modified something so you are merely
checking what would normally go wrong.

Martin

Just curious: What exactly is the difference between these two? The 75µ came with the Beogram, so I suppose this is the orignal. Unfortunately the stylus didn't survive shipping, so now I'm using the 15µ.