1957 Telefunken Opus 7 Repair & Bluetooth Mod

UPDATE:

So I’m running a 3-part LIVE workshop that takes us on…

A Time Travel Through Vintage Electronics.

We’ll rewind the clock, dive into the tech of the times…

(and study the very history of how things were broken and repaired has evolved)

The workshop is coming soon, but if you're reading this then you're in luck (or not)...

And there's still time for you to sign up using the link below:

The workshop dates are mentioned in the link above too.

---

Mark repairs a 66 year old Valve Radio, made by Telefunken in Germany. It was certainly a high-end item in its day, but had acculated quite a few problems over the years. Mark also installs his Bluetooth Interface Board inside, bringing it into the 21st century!

[MendItMark]

UPDATE:

So I’m running a 3-part LIVE workshop that takes us on…

A Time Travel Through Vintage Electronics.

We’ll rewind the clock, dive into the tech of the times…

(and study the very history of how things were broken and repaired has evolved)

The workshop is coming soon, but if you're reading this then you're in luck (or not)...

And there's still time for you to sign up using the link below:


The workshop dates are mentioned in the link above too.

[pleasant]

How on earth did you acquire such intricate knowledge of your subject Mark? You surley must have started when you were very young. With your enthusiasm for the work, you make it look so straightforward but to be able to identify faults amongst such a hornets nest of components is a truly gifted talent. Your videos are an absolute joy to watch.

[atw]

WOW mark chongx caps REALLY 😳 on the filter caps (Chinese junk)

[colday]

Always a great night when Mark gets a new video out!

[tonybalm]

There's nothing like the glow of a magic eye. Brought back memories of when my late father used to repair these. Thanks Mark

[maksqwe]

If you ever need dual can caps, they still make them. I service tube amps and regularly order them. Usually from Hotrox or Watford valves. JJ, F&T and ARS are all decent and always available. Excellent video, as usual!

[leonkiriliuk]

OH NO!! You're using ChongX capacitors!?? :(

[jcollins]

I know nothing about electricity or electronics, but these videos are fascinating! Thank you Mark, always a pleasure!

[EsotericArctos]

A lot of the German made radios had a lot of features like this in this era. They were made so well too.
Lovely radios when you get them going. A lot of the paper caps and electrolytics in the filter will be needing replacing in these, but it is always good to see some proper trouble shooting done instead of just wholesale replacing the capacitors. A lot will be like this one and not operational due to the capacitors and sometimes resistors that drift in value. Those old paper capacitors go acidic inside and the paper breaks down, . They basically turn into resistors internally, which is why a lot of restoration channels will just replace all paper caps. The "Black Beauties" are also paper and foil inside. Guess it is hard when you are doing it for a customer to know how far to go as it takes time.
The Ferrite rod in this likely originally had rubber mounts and plastic brackets that held the ferrite rod in place. Epoxy will stop it moving for a while.
I usually put the bluetooth on the tape input on these when I do them. That way the bluetooth only works if tape input is selected. I designed my bluetooth module to run off the 6.3V AC heater line rather than adding an extra transformer :) There is usually plenty of power available and the bluetooth takes very little current.

[kayvan]

The confidence of Mark is unbelievable, an example of an expert who smiles when something goes wrong.

[oldgold]

You made a fantastic job of that Mark, especially with the Bluetooth added to it.👏👏👏👍

[cphrpunk]

It’s funny, I’m American and I far prefer the term ‘valve’ over ‘tube’, to me it makes more sense.

Given the frequency that caps turn out to be dodgy, why not just replace all of them to start with? The OG ones in there will likely just have issues in the future as well.

[andrea.dalessandro]

Very very interesting. I have a question, though: why didn't you use the tape input ("Tonband") for bluetooth? So it would have been selectable from the appropriate button...

[exiledscouser]

Great to see another cheery journey through old tech with Mark. Great content - thank you!

[gavinrfuller]

As always, a pleasure to watch Mark. You really brighten up my day. They sure don't make them like they used to, in many ways it's so much easier today.

[kamakotim.s]

Hello Mark, I had been watching your videos (all), which is quite interesting (your fault finding techniques), always wait for your new videos, I used to check once daily for new updates. But this time, I would like to have a discussion regarding Yamaha Rx-V463 5 channel AV receiver, that broke down while playing, completely dead now, I need your help in that. I had found out it is from the standby transformer, but I could barely get the same ohms or same type as replacement, I did not find any alteration to do in that regard. Kindly help me please.

[garryparker]

What an absolute gem to restore to beyond it's original capacity. Awesome work Mark

[petervogl]

A very nice great repair. I like it. But let me give you one advice: these brown metall-paper capacitors (Brand ERO) are really bad in general after 60 years. Especially when used as a coupling condenser their leakage current may even destroy the power tubes and/or lead to damage of the speaker transformer due to increased bias current. (One end of the coupling condenser goes to Anode of the preamp stage leadind 150V, the other lead goes to control grid of the power tube which has -7, 5V in respect to the kathode of this tube. Any little leakage can cause a big problem) So i don´t take any risk at all, they go to the garbage bin first before I just even think about to put power to the radio.
Testing them on a insulation tester they all read bad, because the tar seal is cracked and the paper dielectric has absorbed moisture from the air. You could try to cook them in wax, driving out moisture, but the result and sustainability is quite questionable. Modern foil caps are just much better.
And there´s another spot where such a 5000pf ERO can cause serious risk of electrical shock. It is connected across the chassis and one of the power supply conductors.
I'm not sure about the situation in GB, but in Germany it is possible to insert the power plug in any orientation. Therefore the mentioned cap can either be connected to N or L. Nowadays a X1/X2 safety capacitor would be required on that spot. The reason for this capacitor at all is to ensure good AM-receiving quality, when poeple were lazy to connect the ground wire. Many people understood the necessity of an antenna for radio reception, but they did not understand the importance of a good ground connection as a counterpoint to the antenna. To avoid annoying complaints, many manufacturers decided in favour of this capacitor.
For the radio waves, it doesn't really matter whether you use the L or N wire as the aerial opposite pole. But it's no fun for people if this damn capacitor fails and the chassis is now at 220V potential.
As a safe solution for my projects, I have decided to remove this capacitor without replacement and instead use a three-core mains cable with PE conductor and establish a safe connection between the chassis and PE. The local safety regulations must be observed here. Remember: not only you, but also people you love want to enjoy the radio.
With best regards from Germany
Peter

[proluxelectronics]

You cannot beat UK electronics engineering channels, so relaxing and informative. Big Thumbs Up.

[MF_VML]

Any reason why you injected the bluetooth where you did rather than hijacking one of the (unused?) turntable / aux inputs? You could then have selected source directly?
Always an enjoyable and informative watch! Cheers