Without a working sample and no immediate experience with servicing this particular
set, it's a bit hard to tell what to consider normal and what to expect.
However, I would think that for a normal listening volume, the volume control would
have to be somewhere around its center position so even if this is merely a 3-valve
construction (not counting the rectifier), it still left a bit to be desired.
Besides, the AGC was still not active which also confirmed that not all was well yet.

Next, my attention was turned towards the frontend valve.
The CCH2, of which I now have three, would be the next thing to check.
Swapping between the three valves left me with two working valves, one slightly
better than the other in the form of more stations received, and one completely
dead valve.
The best valve being the one that came to me with the set.

Check valve voltages.
The heater voltage was low - what is going on here ?
According to service data, the CCH2 heater voltage should be 20 Volts which was
close to the measured. A couple of online datasheets, however, stated 29 Volts.
When I measured the heater voltages initially, I just took the CCH2 since it was
fairly easy to access and the 20V seemed right. The rest of the valves heaters had
to be correct too since this is a series chain, or at least I assumed that.
I then measured around a bit and found all the heater voltages to be low.
The un-original dropper resistor is of the adjustable type, a small screw losens
a bracket that slides up and down the resistor to set its resistance, and it was
then set to match the datasheet heater voltages exactly.

Powering up again left me with a few more stations and just slightly higher volume.
Still not quite home.

Back to the frontend valve.
Unable to find an unused CCH2, I was adviced to try mounting an ECH3.
The function of the ECH3 is very close to that of the CCH2.
Most functions and specs are the same, even the pinout is an exact match, only
the heater voltage is different.
The heater current, fortunately, is the same which makes life much easier when dealing
with a set with a series heater chain.
The CCH2 heater took 29 Volts, the ECH3 only 6,3 Volts so the dropper would have to
be changed to suit this new situation.
Since this is, at least for now, a temporary setup, I didn't want to mess up the
freshly adjusted dropper resistor but instead calculate a second dropper to add to
the series chain.
Ohms law in action; We have to drop (29-6,3) = 22,7 Volts.
With a heater current of 200mA, the resistor calculates to (22,7/0,2) = 113 Ohms
The power handling of the resistor should be no less than (22,7x0,2) = 4,5 Watts

Two 5W resistors were paralleled to give the desired resistance and adequate power
handling and a brand new ECH3 was fitted.

Warming up the set again - this time with the voltmeter across the ECH3
heater, looking fine.

The set came to life and this time with a decent output volume.
Stronger stations are now loud enough for me to want to bring the volume down a bit
but the AGC is still not doing anything - or at least very little in that it
works from -0,3 Volts to apprx -0,4 volts and that according to the tuned frequency
rather than the signal strength of the tuned stations.
Obviously, there's still something to do but it did confirm that none of the CCH2
valves are very good and the ECH3 may well end up a permanent solution with the
dropper resistor value set according to this situation.

If it was twice as easy, it wouldn't be half the fun. 😂

Martin

Martin, I truly admire you patience with this. So I take it your own Beolit 39 is in a non working state then?

Craig🙂

Nearly there- Check the AGC line for

resistors gone high- they usually do

and leaky capacitors - even a tiny leak may kill the AGC - I haven't got the circuit so can't be sure, but if its the original capacitor it will probably need changing.(Temporarily swap the components for new ones)

Occasionally the low value caps go O/C so its worth testing for that too Good luck

Thanks for the comments and suggestions. 🤒 

The AGC components seem fine though I will be replacing the
related capacitor regardless.
Still, a constant low AGC line should only keep the amplification high
so I doubt an AGC fault in this case.
It will of course be checked and the IF alignment will be up next. I will have
to make up a tool to trim the coil core. It's a hex nut sitting far down the long
coil former and any metal objects in there would only disturb the setting so the tool
will have to be plastic, wood or some other non-metallic material.

Martin

Again, it has been some time. Work on the Beolit 39 project has progressed only
slowly but has not in any way halted.

It turns out, I live in an area with only limited AM reception.
Geographically I find myself in a valley ontop a hill, not the best position
since AM generally is greatly directional.

However, with a fairly long outdoor antenna (apprx 20 meters) and a good grounding
(central heating radiator), a good grounding is essential, I managed
to pick up more stations and the volume was much better though the AGC
line still didn't do much.

Time to start transmitting a reference signal.
I have an AM radio transmitter that I programmed to a frequency in the
middle of the MW band where no other stations could be heard.
A wavelength of 400m calculates to apprx 750KHz and the transmitter was
powered up, fed a music signal from a CD and using just apprx 3m of wire
as antenna.
The Beolit was then warmed up and tuned across the MW band. Lots of stations but
suddenly a loud burst from the new local station.
A cloud of dust was emitted from the speaker as I flew towards the volume control.
Now the AGC line did something and the volume was certainly NOT lacking anything !
A little tweaking of the IF coils to peak the signal and a little more testing
reveals the Beolit to be in fine working condition indeed.
The problems I had, turned out to be nothing more than me living in the wrong place.
The radio played Glenn Miller's greatest hits happily for about an hour.
This about concludes electronic repairs to the chassis.

Martin

BRAVO!

you know what they say: location, location, location! 😂

So true, Jeff.   😂

This is about as lucky as one can get, and still not quite home and dry.
Explanation follows but first take a look at what I've found;

Login to view image

Martin

The dial lamp in the photo is a NOS (New Old Stock) dial lamp originally produced for
the Master DeLuxe 39K as can be seen on the white printing on the glass
envelope.

Obviously, the lamp is of the same family as the Beolit 39/40 lamp but not quite identical
in that the interconnects are different to match the Master Deluxe's two series of
valve heaters rather than the Beolit's one.
The interconnects could be converted to match this lamp by rearranging the leads
to the lamp socket but the filament voltage is far from correct, making this lamp
unuseable for the job.
So close and yet so far...

Martin

Martin, it is great to hear you at the end of this restoration.😕

Craig🙂

A very good personal friend of mine in Germany who also happens to be a fellow
B&O collector and restorer and who also follows this thread, asked me to send
him one of the Beolit 39 knobs. Obviously, he had an idea.
Knowing him and what he can do, visiting him and seeing what he has accomplished,
I didn't hesitate and I was very excited to see what he had in mind.
Just a couple of weeks later, this photo was in my mailbox, looking very promising;

Martin