I noticed a little beauty up for sale at a local auction recently;
A Bang & Olufsen Master 39K in what seemed to be perfect condition.
The thought of bidding on it soon occured to me but I somehow managed to resist
the temptation. Though not quite as good looking as this particular one, I have a
similar set in my collection already that I am really looking forward to restoring.
I've restored several basket cases in my time and it was always great fun and
very rewarding but still, it would be nice to restore a set that obviously
has been cared for to an extreme extent all of its life.
Anyway, it went to a new danish owner at a more than fair price.

A couple of days after the auction ended, I was contacted by the new owner.
He asked if I thought the radio would be safe to power up and/or which things
to check before eventually doing so.
I gave him a couple of ideas regarding what to check and how but partly
because the radio was in a showroom geographically much closer to me than
him and partly because the new owner was a bit afraid of ruining something, we
agreed that I went to the showroom and picked up the radio, brought it with me home
and gave it a good check. That would also spare the poor thing from a potentially
very dangerous trip with a courier across the country.
I was - and still am - extremely busy these days so the radio stood untouched a
couple of weeks in my humble repairshop before I could set aside time for it.
Now, the time has come, even if work on this set as well as my reporting back here
may be a little on-and-off. It's summer in Denmark, we have a heat-wave and there
are so many other things to do but I probably won't be able to leave this
wonderful thing alone.

Martin

Oh what a beautiful model. Looking forward to the rest of the thread

The first thing that struck me was the exterior condition of this radio.
It looks absolutely new !
This is very rare to see for a 70+ years old radio.
It has one scratch on the cabinets left side, looks a recent mark and it was
mentioned in the auction listing but apart from that it is unbelievably beautiful.
Not a single mark anywhere.
No fingerwear on the buttons - they are shiny and smooth as new. I never saw this
before unless polished by myself.
No fingerwear around the buttons - if buttons were ever manipulated it would
have been with the utmost care not to touch the cabinet behind them (think long nails).
A very tiny flaking to the lacquer at the rattan mesh in front of the speaker was
to be expected from the millions of tiny vibrations from the speaker cone sitting
just behind it.
And no dust have collected at the groove at the bottom of the dial glass.
Unbelieveable !
It must have been covered when not in use.

Martin

Looks in absolutely beautiful condition Martin - the sneak preview I had doesn't do it justice

Chris.

Unbelievable, to see a Master 39 K in such beautiful condition.

I'll follow the thread with great interest.

Rudy

Looks beautiful - I'll be following this thread with great interest.

You know we are very lucky - think of all those poor sods who hate B&O and get their kicks from drooling over microscopically small Chinese SMD components in yoo-hoo-bla-bla Digital wonderpieces.

Menahem

At the backside, three service stickers reveal that this radio has indeed seen
use as it was serviced by the same repairshop in 1950, 1953 and 1956.
A repairshop in Slangerup, not very far from where I live and where the radio
was auctioned.
So this radio was definitely cherished, not only while in use but also later.
The usual marks of 40+ years of storage in the basement or in the attic, burried
under various other "useless" stuff, are non-existent here.
Note the telephone number 8 and later changing to 320, suggesting a small town with only a few phones
and the radio repairer was one of the first in this town to have a phone.

Martin

Simply wonderful. A real find for the lucky owner.

Everything looks wonderfully original, - well, there is one thing; A socket at the
bottom left corner of the rear cover is not original.
It's labeled "Telefon" (telephone), which puzzles me a bit. I'm sure the
explanation is to be found inside.
The label is held to the rear cover by two rivets, cleverly mounted
using two existing ventilation holes so as not to ruin the rear cover.
What a sense for detail.
The large round hole, where the socket is now mounted, was already there.
I've noticed it on other sets too, only they were all empty.

Martin

Why 'Telefon' then Martin????

Thanks for your interest and comments. Makes it all worthwhile.

The Master 39K was the second-largest table model of the year 1939, the
Master Deluxe 39K being top of the range, not counting floor-standing models and radiograms.
The models of the same year also included the famous Beolit 39 of which I had the
pleasure of fiddling with one just two years ago.
That story can be found here http://forum.beoworld.org/forums/p/18607/137835.aspx#137835

Martin

Being a quite advanced radio for its time, the Master 39K was meant for use in
the livingroom as the primary entertainer.
It has a comprehensive AM coverage and connection for a grammophone.
You could hardly wish for more back then.
Well, that should maybe be B&O's then newest invention, a revolution for
the daily radio user, the convenient pushbutton station selectors. A first for B&O.

Martin

Wow! What a great condition this old radio is in! It will be my pleasure to follow up on this thread, as you always make really exiting restoration threads :)

Let's take a look inside;
The rear cover is held to the cabinet with two clips.
No screws and no tools.

Martin

The mains power comes in through a plug mounted to the rear cover so will automatically
be disconnected when the rear cover is removed.
That does not mean that the chassis is safe to touch though.
I will not go in to the same degree of detail as I have done previously on this
subject but merely repeat that servicing a valve set like this can be a risky business.
Voltages higher than that of the mains can be found inside the set and if you don't find
them yourself, they will find you !
Never rest one hand on the chassis while working with the other. Keep one hand on
your back and never touch anything unless you are absolutely sure that what you
do won't kill you.
Even when switched off, both the chassis and several components can still hold
full mains voltage or more.
You can read more about safety with valves in my previous restoration write-ups.

The chassis is held to the cabinet by 3 large screws with bakelite heads and even
larger metal washers.
One screw has tiny bits of what seems to be the remains of a red sticker.
There's not enough left of it for me to read anything but it has been sitting across
the screws head and washer so will most likely have been a warranty label.

Martin

Nice view of the innards.

Martin

Martin, have you noticed that "your" set has diferent names on the station pushbuttons?

Rudy

Both versions are commonly seen (well, as common as these get, anyway).
There were two different chassis versions (mainly due to a change to CL6 output valve
instead of CL4, I believe), and I'm almost sure that the default stations were
reconsidered at that time.
You can check if yours is the early version with the CL4 output valve.
The one on my bench is a "version II" as B&O calls it in the service manual, i.e
the "later" version with CL6.

Having said that; The pushbutton station selectors each covered a certain frequency
range and any station within that range could be set to the given button.
You could not change the range though, this means that not any button could be set to
any frequency and all "re-programming" of the buttons would have been done at
the repairshop where correct instrumentation was available.
And the tuning stayed correct for years.
My guess is that buttons with non-default station names could be ordered from B&O but
I haven't been able to confirm this.
It may not appear very convenient seen with modern eyes but to just be able to
select a station at a simple push of a button was hot news back then.
Even a child could change station.

Martin

Two versions of the radio was offered. One for the Copenhagen area (called 'Københavneren') and one for Jutland (called 'Den jyske').

The Copenhagen model started with København on the pushbuttons where the Jutland model bagan with Hamburg instead.

Furthermore, if a customer wanted other stations than the two models could offer, the radio could be ordered with the specific wishes.

Thanks Vifa, for the interest and comment.
So that is the explanation.
It makes perfect sense here in that this set was in use only 25 Km or so from Copenhagen.

Martin

Martin,

I've checked mine and I have  an early version with the CL4 output valve.

Serial number of my set is 41586.

Thanks Vifa for the explanation  on the Copenhagen and Jutland version.

Rudy

The start of another great thread, Martin. Looking forward to it -and what a beautiful piece it is!

Thanks Jaff,
Nice to know that there are people following this thread. 

Rudy, that's interesting. I'm working on chassis no. 41548 and it has the
new circuitry and a CL6.
Of course, we cannot rule out that one of them was modified at some point but
I doubt that it could be the one, I have here. It shows absolutely no signs
of modifications of that sort whatsoever. But on the other hand, it's not very
likely that your set was modificed back to CL4, is it ?

Martin

Hi Martin,

You're right.

I double checked my set and itn also has a CL6. 

Must be a mistake in my tube database.

My mistake.

Martin, could you later on suggest an alternitive for the Master 39 K dial lamp?

it's missing in my set.  

Rudy,

Thanks for this nice photo of your set.
Looks like you already found an alternative for the dial lamp ... 
Seriously, these have proved incredibly hard to find and probably
easier to replace by something else. It seems to be a 110V lamp and the current
is the same as that of the valve heaters. I made a temporary solution
in a Beolit 39 for the same reason.
I will keep an eye out though.
Now I think of it, I am always keeping an eye out for parts and info.
Maybe someone can tell us if the same lamp is used in f.e. Master Deluxe 39K ?

I noticed the grid cable to the output valve, it is screaming for attention. 

I also noticed your Master 39K does not have the output transformer mounted
behind the speaker and not on the speaker itself. Where is it then ?
The speaker looks exactly like mine and is a Peerless "Orkester" 5 Ohms type.
The output transformer is listed as a Peerless CL4 like the one I saw in Beolit 39
but in this Master 39K a B&O output transformer has been mounted as
you can see. Maybe to carry that "Telefon" connection too. Who knows.
The CL4 transformer is somewhat smaller than the B&O.

Martin