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Opus-Stereo 2004 Nußbaum

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For model Opus-Stereo 2004 Nußbaum, Telefunken Deutschland (TFK), (Gesellschaft für drahtlose Telegraphie Telefunken mbH
Country:  Germany
Manufacturer / Brand:  Telefunken Deutschland (TFK), (Gesellschaft für drahtlose Telegraphie Telefunken mbH
Year: 1959–1961 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 10: ECC85 ECH81 EF89 EF89 EM84 EABC80 ECC83 ECC83 EL84 EL84
Semiconductors (the count is only for transistors) OA180
Main principle Superheterodyne (common); ZF/IF 460/10700 kHz
Tuned circuits 8 AM circuit(s)     12 FM circuit(s)
Wave bands Broadcast, Long Wave, Short Wave plus FM or UHF.
Power type and voltage Alternating Current supply (AC) / 110-240 Volt
Loudspeaker 4 Loudspeakers
Power out
from Model: Opus-Stereo 2004 [Nußbaum] - Telefunken Deutschland TFK,
Material Wooden case
Dimensions (WHD) 675 x 385 x 280 mm / 26.6 x 15.2 x 11 inch

Mit KW-Lupe
AFC wird aktiv beim Loslassen des Abstimmknopfes. 

Net weight (2.2 lb = 1 kg) 18 kg / 39 lb 10.4 oz (39.648 lb)
Price in first year of sale 559.00 DM
External source of data Erb
Source of data HdB d.Rdf-& Ferns-GrH 1959/60
Mentioned in HdB d.Rdf-& Ferns-GrH 1960/61
Literature/Schematics (1) -- Original-techn. papers.

All listed radios etc. from Telefunken Deutschland (TFK), (Gesellschaft für drahtlose Telegraphie Telefunken mbH
Here you find 3440 models, 3024 with images and 2020 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Telefunken: Opus-Stereo 2004
Threads: 3 | Posts: 29
Hits: 440     Replies: 2
Telefunken OPUS 2004: Fehler im Schaltplan

Die Widerstände W59 und W159 an den Eingängen der EL84 haben den Wert von 220KOhm und nicht, wie im Plan angegeben einen Wert von 2,2KOhm.

Helmut Weigl

Hallo Herr Lucas,

ich nehme an, dass Sie mit Eingang der EL84 das Gitter meinen.

Der Sinn dieser Widerstände liegt in der Unterdrückung der Schwingneigung. Ein Wert wie im Schaltplan von 2,2 KOhm ist schlüssig und im üblichen Bereich. Ein Wert von 220 Kiloohm kommt mir komisch vor.

Haben Sie den Widerstandswert mal gemessen oder sich nur auf den Farbcode verlassen (die Farben kann ich im Bild nicht genau deuten)?

Die Farben des Farbcodes könnten sich über die Jahrzehnte auch verändert haben. Auch der Widerstandswert könnte sich verändert haben.

viele Grüße

Helmut Weigl



Guten Tag Herr Weigl,

natürlich ist pin 2, also das Gitter gemeint. Trotz des Alters wäre eine Farbverfälschung sichtbar.

Ihre Zweifel decken sich mit meinen, aber die orignal eingelöteten Widerstände sind messbar 220KOhm.  Übrigens habe ich zwei Opus 2004 und die Widerstände sind bei beiden Geräten 220KOhm, ein Fehler kann damit ausgeschlossen werden.

Es gibt dieses Modell im Radiomuseum als Praktikumsausführung, ich denke, es wurde zu Zwischen-, Gesellen- oder Meisterprüfungszwecken verwendet. Auch da scheint niemanden der Fehler aufgefallen zu sein.

Versuchsweise habe ich in beide Endstufen R mit 2,2KOhm eingelötet, es gibt keine hörbaren Veränderungen.

Es grüßt

Heinz Lucas

Hits: 3061     Replies: 0
telefunken: Opus Stereo Schematic
George Boettcher Jr.
  1 I recently obtained a Telefunken Opus-Stereo from about 1958.  I need help with a schematic for the unit.   The front panel and tube layout is slightly different from any Opus-Stereo 2004.  This is a German domestic model with FM limited to 88-100Mhz.  Instead of having all the front panel buttons in one row, it has the double row with the tone selection keys in a second row up front, similar to an Opus-7.  Also there are two ECC85 tubes in addition to one ECC83.  (10 tubes total).  The back cover states this is an "OPUS Stereo" but does NOT list it as a type 2004
Can any member help me out with a schematic for this specific model. Thanks
George Boettcher Jr
Hits: 11249     Replies: 24
telefunken: 2004; Opus-Stereo
Jose Duarte Costa

Herr Hans Knoll


I'm one year old, member of Rmorg.

I had been very interested in your technical advices which I appreciate too much.

Also I've one radio set, a Telefunken Opus-Stereo 2004, which has one FM failure.

It receives only one broadcast station in all FM scale.

Tubes were checked.

Unfortunately I have no its schematic diagram.

Also I've not enough experience in these matters, so you can't ask me to reply to your advices very fast, as I would like to do, but I promise to reply to all your advices if you will be so kind to reply me.


Thank you in advance


Best Regards

José Duarte

Hans M. Knoll
  2 Hallo Mr. Duarte,

i receive your Message this moment.

Without Diagramm i think, it is not usable to beginn a Support.

In this Moment i post a Signal: wanted  Diagramm in

I will see, what i can do bevor and come back next days here.
Please wait.

Best regards Hans

Jose Duarte Costa
  3 Thank your reply
Best regards
Jose duarte
Hans M. Knoll

Hallo Mr. Duarte, 

I have seen that you and I searching for the Diagramm. We will hope anyone spend this.

In the meantime I make a brainstorming [ som time i do that ;-) ] 
Your coment : <It receives only one broadcast station in all FM scale.>  give me a idea.  
It seem, there is not a   electrical Failure. Maybe? This set is tuned with "moving Cores"  is called Variometer. 
When inside of the UKW Frontend Box the robe, whos moving those cores, is brocken no Tuning is possible.
see here:

and here:

Also when the Wheel  and  the shaft is not cupled,

the same result is vissible. I have make for you 3 pictures there you can see whats going on.

It is not so easy to test this, you musst open the UKW Box.  Tell me  please what you mean. 

Best regards Hans

Jose Duarte Costa
  5 Herr Hans Knoll
Thank your very much for you ideas.
I checked all the things you told and everything is ok.Now i hear in all the FM scale more than one broadcast at the same time,and when I move scale the light of tube(EM 84) dosen't change.
Once more thank for our reply and the good quality photos.

Best regards
Hans M. Knoll


Hallo Mr. Duarte, 
Your newest  info says:

 Now i hear in all the FM scale more than one broadcast at the same time,and when I  move scale the light of tube(EM 84) dosen't change."
Before this:
It receives only one broadcast station in all FM scale

That's a new situation.  
This phenomena is to observe, when the Cores not moved or, the local oscillator is not present. Can you give a information what FM Stations in Lisboa you receive. Most important,  are frequencies  with a gap of 10,7 Mcs. For example: 88,00 and 98,7 and so on.

If the local oscillator is not preset,  a strong Station take over his function.  We have to clear  this first.

Have you realy testet  the Tube ECC85 on top of the FM Box?

If I have this info, I can further thinking what is next?

Best regards Hans



Jose Duarte Costa

Herr Hans Knoll
Lisbon FM frequencies are the follow.

As I said before, I hear in all the FM scale two stations.
They are: TSF 89.5 and Radio Paris Lisboa 90.4.
The ECC85 was checked and also changed by a new one.
Thank  You.

Best regards

José Duarte

Frequências Nome da Rádio
87.6 Rádio Seixal SEIXALFM
88.0 Rádio Ocidente OCIDENTE
88.4 Rádio Nato -
89.1 Rádio Lezíria RL-FM
89.5 TSF TSF
90.4 Rádio Paris Lisboa RPL 90.4
90.9 Popular FM POPULAR
91.2 Rádio Clube de Sintra RCSINTRA
91.4 Rádio Iris IRIS FM
91.6 - -
92.0 Rádio Nova Antena R N A
92.4 Mega FM MEGA FM
92.8 Horizonte FM HORIZ.FM
93.2 RFM RFM
93.7 Rádio Mais R. MAIS
94.4 Antena 2 ANTENA 2
95.0 Miramar MIRAMAR
95.3 Tropical FM TROPICAL
95.7 Antena 1 ANTENA 1
96.2 - -
96.6 Best Rock FM BEST FM
97.1 Rádio Viva -
97.4 Rádio Comercial COMRCIAL
98.1 Rádio Marginal MARGINAL
98.7 Rádio Baía RAD BAIA
100.3 Antena 3 ANTENA 3
100.8 Rádio Capital CAPITAL
101.1 Romântica FM  -
101.5 RDP África AFRICA
101.9 Estação Orbital ORBITAL
102.2 Rádio PAL PAL FM
102.6 Oxigénio OXIGENIO
103.0 MIX FM -
103.4 Rádio Renascença RR
103.9 Sesimbra FM SESIMBRA
104.3 Rádio Clube Português R. CLUB. P
104.8 Rádio Eco ECO FM
105.4 CSB Rádio CSB
106.2 - -
107.2 Rádio Cidade CIDADE
107.7 Rádio Nossa  -

Hans M. Knoll

Hallo Mr. Duarte,

attached you find a diagramm, i think is the same as in your set.
Please see two Resitors outside of the BOX in this case 8,2 and 33  kohms.

These values depends  from the Supply Voltage off each set.
Please oberve and meassurments the Voltage befor and behind off each Resistor.
The current you can see shut be   aprox. 12 and 3,75 mAmps.


meanwhile send our Member Mr. Eckhard Kull the orig. Telefunken UKW Box of OPUS 2004
The quality is not so good ( its a long journey to me) its only for refence.

Blue arrow= testpoint  -Uosc.   FM local oscillator
New at 1.02.05

I think your 4,5 are to high. Maybe the oscillator do not work.
Use this test to measure the negativ voltage on G1 ECC85 II .
If all O.K. the negativ voltage shut be -2 to -3 volts.

Further you have not answer to Post 5 (moving the cores)
Additional dit you hear the two FM Stations over the whole scale left to right .
How loud is the noise on FM Range much more then on MW?
Its hard job to find whats wronge!

Hans M. Knoll


Jose Duarte Costa
  9 Herr Hans Knoll
I measured and the values are 9mAmps and 4,5mAmps
THank you once more
Best regards
Hans M. Knoll
  10 Hello Mr.Duarte,

i think this 4,5 mA are to high. See my alternations on post 8.

Jose Duarte Costa

Hallo Herr Hans Knoll

-The core's cord is OK it works fine.

- The tensions in 33kOhm resistor are 235V and 84V. So (235-84)/33000= 4,5 mAmp

- The two stations are listened in all scale, mixed and not very clear,. MW is heard  much louder than FM.

Now the negative voltage on G1 ECC85 II:

It was measured  0,00V   but..

When I put the lead terminal inside the hole of the test point, I can hear one station very loud and clear. If I take it off from the hole the tune stands still.

If I turn the tune knob searching another station along the scale, the tune is lost.

 But if I put the lead terminal again, with some luck I can hear another station. Also this new station is heard loud and clear and stands still even after I take off the terminal.

Hans M. Knoll

Hello Mr. Duarte
Its fine you make a good job  Result is, local Oscillator  dues not working.

Next and I think last, you have to test, is a connection between pin 7 ECC85 and ground. Remove the Tube and measure the resistance from pin 7to ground. The value must aprox- 330Kohm. If not, the red marked coil is disconnected . 

In my sample,  all red marked condensers are high quality ceramics.
 I have no idea why one of these in your set, its maybe wrong.

 Fist the 11 pf and 125 pf are important. 
 You can try to put an 10 to 15 pf (green marked) from test point to Case You remember,  the Test dip makes an action.

 Next important is  the 2200pf. ( red ). It is your decision , how to shunt a 2200 pf  for the moment,  to this .( its all in Box) !
If all this without responding,   I have not any idea in the moment. I am sorry

Best regards, Hans M. Knoll



Jose Duarte Costa

Hello Herr Hans Knoll


Sorry for this so late reply. You can understand. I needed a lot of nerve to unwire and open FM case again.


I thank you again for your patience.

I still wonder why it works so good when I touch the test point and it stands working after I take the pointer out. What is the phenomenon?

The measurers you ask me to do are:


Between pin seven and test point ----------- 330 kOhms



            11pF  ------------ 16pF measured

           125pF-------------126pF measured


The test with 10 pF between test point and earth didn't produce any effect.

The two 7,5 pF   presents 8,2 pF measured


I also had made some more checks:


Diode is OK

In pin 2 :  330pF ---- 382pF measured

                   11pF ---- 6,3pF measured

                 Resistor 220kOms---237kOms measured


That's all


It's being hard so I must thank you again for your comittement.

Best regards

Hans M. Knoll

It's being hard so I must thank you again for your comittement

Mr Duarte,
this results < 330 Kohm> are imposibile.

Between pin seven and test point ----------- 330 kOhms

Only if Coil is interruptet,,  and Pin 7 is groundet,,  or ECC85 is heated. 

Pin 7 and Testpoint is conected only thru the red marked Coil.
Lower then  one Ohm must be measured.  

And what is with this Condenser?  Next important is  the 2200pf. ( red ). It is your decision , how to shunt a 2200 pf 

I am sorry,  you must or not?

Hans M. Knoll

Jose Duarte Costa


Herr Hans Knoll


Of course it was a mistake. I'm deeply sorry.

 330kOhms was measured between pin 7 and earth.


About shunting the 22000pF condenser:


 At time I did not understand that it was important do it before a further measuring inside the box.


Of course I'll do it next.

 Next step: I will shunt the condenser; I'll close the box and I'll make  provisory link wires to check it before definitive assembling.


I'll tell you the results in next article.


Best Regards


José Duarte

Hans M. Knoll
  16 Hello Mr Duarte.

I think, you can test the FM Box outsite of the Set.
Is only necessary : DC 220 Volts , AC 6,3 Volt and Earth.
Also without the Case.  
The only failure is at moment, the Local Osc. to not works. To test,  2 to 3 Volt negativ an Testpoint is necessary!

The 2200 pf is inline with the Osc- Coil  and one Part of the Circuit. If these is bad, no oscillation is possible.  I now, it is a hard job. Fact is, no Oscillation, no reception.

All other Phenomenas , i dont now what is audible.  Can you tune different Stations in this case?
The Testpoint is the one and only sesitivest Point in the whole set. 
All frequencies find an Input there.  

Regards Hans M. Knoll
Jose Duarte Costa

Hello Mr. Hans Knoll


I already made a shunt between 2200pF and earth -- nothing happened differently.



I disconnected it and the situation is the same as I told you before:


No tune in, except when I touch the test point.



Such as:


 If the variometer is in its right place (near of a station), I touch the test point and that station immediately can be received.

 It is going on working  in excellent tune even after I take off the touch. It stands well. Radio set seems to be in perfect conditions, until...


 Afterwards I displace the position of variometer. The tune in of this station disappears. It is normal. But..


Afterwards I displace the variometer to another tuning point (another station). Nothing happens... until I touch again the test point. When I do it, that new station can be received loud and clear.

And so on. 


Thank you for your patience

Best regards

José Duarte

Hans M. Knoll
  18 Hallo Mr.Duarte.
Before I write an actual report, please make this additional Test

remove ( resolder ) the two wires from FM Box to the Chassis in this small drawing market
< X> and <X> this is the AFC Controll.

I think at moment  the failure is outsite off the BOX.

New at 16.02. 17:00

This is the AFC Circuit. Please check the red market Resistors partikular the 1Meg Ohm
Your newest Test give me this idea.

More infos after you have testet.
Regards Hans
Hans M. Knoll
  19 See modifications on post 18

Jose Duarte Costa

Hallo Mr. Hans Knoll

At last the guilty one was discovered. One 3Mohms resistor is opened.

 I followed your advices and I tested the resistors near EABC80. Here it is one 3Mohms not a 1Mohms linked to 210V. I changed it and now all is OK.

Congratulations .Set is now working . Thank You very much.

Best Regards

José Duarte



Hans M. Knoll
  21 Hallo Forum.

 20 Posting for one Resistor!  Mr.  Knoll you get old!

Mfg Knoll
Jose Duarte Costa

Hallo Mr.Hans Knoll

In my opinion 20 posting were not because Mr. Knoll is getting old.

It were because his interlocutor is "too young" in this matters.

Some clues sent, were not enough clear to one reach to a quick diagnosis.

Best regards
Jose  Duarte

Robert Sarbell
  23 Profound compliments to both Gentlemen,
I am sure that Herr Knoll knows of the "blind squirrel" cases - when he must dig many times to find the acorn. But, he does not quit, because he knows it is somwhere close.

After many days, I found marginal solder connection within FM pre-amp cage which was sensitive "thermal increase" and then FM stereo went off. Also happened on several other Sansui 1000A receivers built within short time period.

Senor Jose Costa, you are to be commended for displaying persistence with patience.

I am absolutely amazed at the wonderful use of text and the hand-drawn graphics blended together by Herr Knoll. We are indeed honored to follow your performances. The master of a slide rule has mastered the "cyber" rules!!

Un ablazo para Jose,
und mit Viele Grusse to Herr Knoll,
Robert Sarbell

Hans M. Knoll

Hello Robert, 
i thank you for your friendly comment.  I think, you can realize , how many  thought are necessarry to bring it forward.  
For your Eyes,  you remember?  Here  66 2/3 % "oldgemany" and 33 1/3 % "USA" .This are my tools, to search resistors. ;-)

Best regards , Hans


oh, Robert i see!

you mean this one:

yes, this here was my first "TEXAS" for 298,00 DM!


Robert Sarbell
  25 Good Morning Hans,

Yes, many years ago they get much use. But your Texas Instruments is LCD screen. . . .surely your first hand held calculators is using only small LEDS. . . .and not so many trigonometric functions - many tables for that. Even my teacher Herr Kirst did not have hand-held electronics in 1959.



Telefunken: Opus-Stereo 2004
End of forum contributions about this model