Telefunken Jubilate 9 export - help

[Diniz Diniz]

Hi everyone,

My last acquisition was a telefunken jubilate 9 export. The set seems very well preserved. Although, something is not working properly. I'll try to explain....

When I turn on the radio on the FM it is possible to tune a few stations (good quality of signal) but the sound is not loud (compared to other jubilate (1061W) I have). Occasionaly there are "spikes" of a very loud sound and very good quality signal, and it is possible to tune in more sations with very good reception. Sometimes the "spikes" last for a second, sometimes more... I know something need to be checked but I would like to have your advice first.

Thanks in advance and I appologize for the "poor" explanation. It's the best I can manage with my bad english

Cheers

Diniz

[Diniz Diniz]

Hi, I'm still hoping to have your advice, meanwhile, can anyone confirm what capacitor is the "that capacitor" in this set? Is it C32? (see image below)

Thanks once more,

Diniz, Portugal

[TonyDuell]

Yes, C32 looks like 'That Capacitor'

[Diniz Diniz]

Thanks TonyDuell!

Does anyone have a tip explanation for the problem I described above?

Thanks in advance

[murphy512]

Sounds like a dry joint or loose connection.
With a plastic stick check all joints for loose connection
Make sure that the valves pins make a good contact, spraying the pins and valve holders with Servisol may help.

[Diniz Diniz]

Hi,
I've been checking all points for loose connection, and i have heated some points with the soldering iron, and it seems to be better. At least the cracking noise has almost desapeared, although it is now playng not as loud as it used to.
It still have a 'hum' audible when the volume is not at the maximum...??

Ok, but my 2 questions are:
- I realize that when tuning some stations (the ones where i have the worst signal) it stays in the same station for a big interval (for instance from 92MHz to 93MHz) and in some cases there are to stations overlapping. How can i deal whith that problem?

- How do you manage to solder that 'hair thickness wires? It seems that the solder (weld) flee from the wires...

Many thanks in advance, I hope to get your tips!!

[Herald1360]

The hanging on to stations sounds like AFC action. Automatic Frequency Control is often found on VHF set- it's a system which effectively locks the tuning to a station over a range of frequencies either side. It's useful for stopping the set from drifting off tune as long as the AFC "capture" range is larger than the likely drift in the set.

Hair wires that won't solder sound very much like enamelled copper wire used in coils and transformers. The enamel is very thin insulation and older enamels were pretty much solder proof. Newer types are designed to be "solder through" in the sense that the iron temperature is high enough to melt/burn off the enamel. They're still not "easy" to solder, though, and pong a bit if you so succeed!

[Diniz Diniz]

Hi,
Chris, I realy appreciated your comment. Since I am not a english native speaker, I have some difficulty in following the reasoning of some statements in this forum. Mostly when there are technical terminology involved. Can you please talk a bit more about AFC?

Question for all the forum:
The set seemed to be fine, but yesterday the following happened:
When I turn on the set it plays very loud for a few seconds, and instantaneously reduces the volume and stays like that. If I turn off and again (imediatly) turn on the radio starts playing with reduced volume. But if I wait several minutes between the turn off and the turn on, it plays very loud again for a few seconds.
Any tips where should I start investigating the problem

Your help will be much appreciated!

Diniz, PORTUGAL

['LIVEWIRE?']

Hopefully Herald 1360 has explained what AFC is and how it works. Basically it makes tuning to a station 'broader'. Some radios, possibly including the Jubilate 9, have switchable AFC, the idea being to tune in with the AFC switched off, then switch it on. AFC will 'pull in' a station i.e. minimise the effect of any drifting of frequency. It also to some extent prevents weaker stations on nearby frequencies from interfering with the wanted programme.

[Herald1360]

AFC uses the dc output from the FM detector which is zero when the set is correctly tuned and swings negative or positive as the tuning varies either side of correct. Too far away and the voltage drops back to zero as there is simply too little signal to give any voltage. This voltage is used to control a voltage variable capacitor in the local oscillator circuit in such a way as to drive the detector dc (error) voltage back towards zero. This results in the effect described where as you approach correct tuning the signal jumps into lock and is held there until the tuning is far enough out on the other side for there to be no dc voltage left at which point the system loses lock on the tuning.

[Diniz Diniz]

Thanks a lot 'Livewire' and Chris for the very elucidative statements about AFC. I was not aware of it, and since my main purpose is to learn something, I am very grateful.
I dont know if when 'livewire' mentioned switchable AFC, it means that is possible to swicth it on and off... since I can not find nothing on the set allowing that. (images below)

I would like to kindlly ask you both if you can suggest me something regarding the volume problem I've described. The set starts playing quite loud, and remains like that for a few seconds, and after that period it instantaneously reduces the volume... I already tested other valves and the problem persists... could that symptom be related with C32, the 'that' capacitor in this set?
Your help would be much appreciated.
Thanks again for your availability

Diniz, Portugal

[Freya]

Does the volume level return if you operate the keys on the front, switch from FM to AM and then back.

['LIVEWIRE?']

I don't see any indication as to the function of each button, Diniz, and I forget what the German for 'AFC' is. A circuit diagram or clear illustration of the front panel showing which button does what may help us to determine whether or not the AFC is switchable. If, as Freya suggests, the volume level returns when the keys (buttons) are operated, then it's likely the switch contacts are faulty and (further) cleaning will be needed. As to 'that' capacitor, wihich connects between the anode of the first audio amplifier valve and the control grid of the output valve, if it hasn't already been changed, it should be. Check if there is a positive voltage on the control grid. If so, that capacitor is suspect.

[ms660]

If it has AFC I wonder if there's an AFC switch incorporated in the FM tuning control (push or pull operation) In the second picture there seems to be a gap between the two control knobs that are on the right hand side of the receiver, unless they've not been fitted correctly?

Lawrence.

[Diniz Diniz]

Hi,
I will try to reply the 3 last comments, which I really appreciated! Thanks.

Freya, I've followed your tip, and it happened as you described, the radio plays louder in AM band. (I'll come back to this topic).

Livewire, I don't see any indication of a switchable AFC in the front panel, but I will add some more pictures I just take. Regarding C32 (that capacitor) I already replaced it. I was planing to replace C31 also, but it has 3 legs (??) and I don't have nothing similar to replace it.

Lawrence, I don't believe there is an AFC switch incorporated in the FM tuning control. The outsider knob on the right hand side of the receiver was, indeed not been fitted correctly, since I applied some lubricant on it.

I have inspected the FM switch which is quite inaccessible (I don't know how to look inside - img_7). When I pressed one of the wire/contact the set starts playing louder. I believe it could be the cause of the problem, but I will test it again tomorrow, otherwise the neighbours will complain

Cheers

[Freya]

A Telefunken Decapo 9 of mine had the same problem which I ended up solving with a dental t-pee brush inside the switch with switch cleaner, a bit of a job to do.
Noticed on your last picture it seems to show some dodgy looking capacitors remaining.

[Diniz Diniz]

Thanks Freya for the advice, I will try to follow your procedure!

Regarding the dodgy capacitors, I will replace them today and I will let you know if it has any impact in the problem.

Regarding C31 (see images attached), which is a 3 legs capacitor, how can I replace it by a 2 legs I have read some time ago here in this forum that the 3rd leg is kind of a 'screen', though I dont know the meaning of that...

Your comments on this are welcome!

Diniz, PORTUGAL

[julie_m]

Just ignore the ground connection, and connect the two plates of the capacitor as shown in the diagram.

If the set breaks into oscillation, you will need to arrange shielding for the capacitor by wrapping conductive metal tape around it, and connecting this electrically to the chassis of the set.

[Freya]

I ended up making a tight fitting coil of wire over the new capacitor, heat shrink tubing over the coil.

[Diniz Diniz]

Hi,
Thanks Julie_m and Freya for your tips. One day I would like to see an image of the procedure you described, in order to better understand how to do it myself.

For now I just left a new 0.01uF capacitor (2 legs) in C31 position.

After replacing C33 and C26 (I replaced both at the same time) the set started playing properly (loud sound) with no intermitencies. Tomorrow I will test it for a longer period, but I believe it is nice now.

I was wondering if the problem concerned to C26 or C33, and why did (the capacitor causing the problem) just affect the FM band and not the AM. Since my purpose is to learn something, I have attached below the diagram including C26 and C33, to see if anyone has an idea.

Thanks once more for your precious help.

Cheers,
Diniz, PORTUGAL