emud: 60; Rekord-Senior
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.Attachments:
- EMUD OT (80 KB)
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.
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.
Hello Mr. Saltzman
I uploaded a schematic of the Emud Rekord Senior 60 USA-Version kindly provided by Otto Künzel.
Perhaps it helps.
Click on the “To the model” seen above. Mr. Günzel kindly uploaded a better clear schematic that should help you a lot.
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.