emud: 60; Rekord-Senior

ID: 237512
This article refers to the model: Rekord-Senior 60 Export (Emud, Ernst Mästling; Ulm)

? emud: 60; Rekord-Senior 
21.Nov.10 04:18
58

Mark Saltzman (USA)
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Count of Thanks: 10
Mark Saltzman

Gentlemen,

While performing capacitor replacement and circuit tracing to verify connections, I noticed that the Output Transformer (OT) connections have been modified beyond recognition.  The OT looks just like other EMUD OT's I have found in the model pages, but may have undergone repair or modification during its past lifetime. 

A tone cap that should be mounted on the tone switch assembly has been moved to the OT.  I would like to re-install in its correct location, but unsure which contacts and what value to place here.   

The feedback circuit from the OT to the volume control is completely missing, all resistors and caps that should be located on the OT solder lugs are missing, and no feedback connection to the volume control.  It appears to have been connected Single Ended as the Primary CT(B+) and R39 are connected together at the OT.  I have inspected the OT and found two taps for the primary and 3 for the secondary, but it doesn't look like it has enough to make all the correct connections required by the schematic.

The photo shows the seconday winding and the some of the lug connections.

Any help in this matter would be greatly appreciated.

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 2
Picture of chassis. 
21.Nov.10 21:13
58 from 3351

Paul E. Pinyot † 2013 (USA)
Articles: 187
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Paul E. Pinyot  † 2013

I have this picture of the chassis from this page.  It is hard to see the parts.  But you may get an idea of how they are connected. 

The RM.org Senior 60 schematic (not the export) is clearer than your export model.  You should get an idea of the parts, values and connections if you compair the Export fuzzy schematic with eletrostatic tweaters to the Domestic clear schematic with dynamic voice coil tweaters. 

Be careful.  There is additional feedback on the EL84 Grid 2 Export version that is not on the Domestic version.

Perehaps some one else with a clean Export schematic will verify the secondary feedback resistor and capacitor values for you. 

Paul.

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 3
Still at square 1 
22.Nov.10 04:54
87 from 3351

Mark Saltzman (USA)
Articles: 8
Count of Thanks: 7
Mark Saltzman

Mr. Pinyot,

Thank you for the reference.  In fact, I had studied your photo from your website at length before I decided to post.  BTW, your website is FANTASTIC !!!  It was your photo that allowed me to ascertain that something was amiss with the OT and related circuitry.

Although your photo was very helpful, it unfortunately does not assist me (at this point) in getting from what I have to what I should have.  The lack of a correct circuit in my hand makes it difficult for me to trace as per schematic.  As you know, failed components is one thing, but missing components, especially when placement can at times be critical, is another. 

I guess the information that I was looking for has more to do with a recognition, by fellow techs familiar with the EMUD, of what may have been accomplished by doing this or an acknowledgement of an improper OT, or production run change that is similar on other radios of the same model.

Thanks again.........still at square 1.

 

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Schematic USA-version 
22.Nov.10 17:43
133 from 3351

Thomas Günzel † 1.8.22 (D)
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Thomas Günzel † 1.8.22

Hello Mr. Saltzman

I uploaded a schematic of the Emud Rekord Senior 60 USA-Version kindly provided by Otto Künzel.

Perhaps it helps.

Kind regards

Thomas Günzel

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 5
Verify the chassis on the schematic with red & green pencils 
24.Nov.10 03:52
197 from 3351

Paul E. Pinyot † 2013 (USA)
Articles: 187
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Paul E. Pinyot  † 2013

Mr. Saltzman,

I have been thinking about your situation. I often come across radios that someone has modified. One example is a Saba Frieburg 14 with automatic tuning. What a nightmare. Lots of changed values in the autotune circuit. This is what I do for just about every radio that helped me put the Frieburg back to original.

Click on the “To the model” seen above.  Mr. Günzel kindly uploaded a better clear schematic that should help you a lot. 

I print out the schematic over at least two sheets of paper. Why struggle with reading the values? (I am 52 as of last Sunday and my eye sight is not what it used to be). Your printer may have an option that allows multi page printing of a single page. Then trim and tape it together. 
 
As I go through the restoration (replace capacitor, selenium diodes, ohm out RF/IF & power transformers for continuity, valves, etc) I mark each component symbol with a red or green pencil. The red is for all parts that are bad, out of tolerance or questionable that I replace. The green is for tested good parts (i.e. IF transformers) that are kept. (I do not mark the dial lamps).
 
When I do this I am looking at the connections to see if the parts are connected as indicated in the schematic.  I always remind my self that some one may have been into the chassis before me.
 
When some circuit is miss wired I use the green pencil to trace all the good junctions and circuit paths. I stop tracing when I find a fault or missing parts and fix those problem circuits. This effort is typically limited to one valve stage (more for ham radio gear).
 
For your specific situation I suggest starting tracing at the plate of the audio output valve V5 pins 7 (plate) and 9 (grid2).  You may need to go back to V4-8 grid for all the feedback circuits.
 
Comment - Do not be surprised if the installed V5 cathode resistor R57? is the wrong value.   I find here in the US people play with that resistor (for what reasons I can only guess).  This is a great example to use current limiting devices on the mains to test the unit BEFORE any restoration efforts.  You may save a valve!
 
All this red/green tracing effort helps to systematically Un-modify the chassis and keep track of your restoration efforts all at the same time. This is real important to do with Ham Radio (amateur) gear. You should be able to identify the missing parts to your circuit through this “process of elimination”. 
 
Once identified, you then can obtain those parts and wire them back into the chassis. The worst you can do is solder them into physical positions that are not factory locations.
 
Give the marked up schematic a try,
 
Paul.

 

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 6
Good place to start.... 
24.Nov.10 05:22
207 from 3351

Mark Saltzman (USA)
Articles: 8
Count of Thanks: 7
Mark Saltzman

Mr. Gunzel and Mr. Pinyot,

I sincerely appreciate the assistance.  The new schematic appears to be clearer and has allowed me to identify the correct values within the circuit that were not quite legible in the earlier schematic.

I will trace the schematic and although I normally just mark the circuit while tracing and stop and fix what is in error, I like the two color method suggested and will try it. 

I also treat vacuum tube electronics as though it has been serviced, modified, or just plain old, and never power up until the circuit is true per the best obtainable schematic, the caps are replaced, and tubes have all been checked (initial power up with no tubes).

It was during circuit tracing that I found something wasn't correct, and referred to your photo Mr. Pinyot.  Your photo verified what my tracing had found (or NOT found) and was most helpful in this regard.  

I posted the photo of what I actually have, to see (just in the odd chance) if this was some sort of "common" mod, or if someone could visually identify something amiss with the OT as compared to a correctly wired OT.  Upon my initial inspection it appears that I am not only missing some components, but that the OT does not have the correct amount of winding taps to match the schematic.  I may just have an EMUD OT that is for another model, placed there in an effort to repair the failed original.  It appears to have no center-tap for the primary, and no feedback coil tap for the secondary.

Our methods are on the same page and I welcome the advice given.  Thank you very much.

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