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Old 13th Jan 2020, 11:06 pm   #1
briscaF1
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Default Telefunken Operette Radio advice

Hi all,

I've got this old Telefunken Operette (as shown). Some of the resistors and capacitors are damaged (cracked, holes in them) as though they have seen too much voltage/current at some point so I think it may well be very poorly.

I've partially stripped it as was going to turn it into a Bluetooth speaker by gutting it and putting an amplifier plus a couple of speakers in it but it seems a shame to do this plus I didn't want to go ahead and trash something that might actually be rare.

What's the view on this, please? Worth saving or best to continue life in a new guise?

Thanks in advance.
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Old 13th Jan 2020, 11:49 pm   #2
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Default Re: Telefunken Operette Radio advice

Also, I guess this is a HCH81 model, circa 1955 (looking on radiomuseum.org)?
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Old 13th Jan 2020, 11:55 pm   #3
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Default Re: Telefunken Operette Radio advice

Looks quite clean and tidy, certainly worth a restoration and you can possibly also add the Bluetooth as well.

Ed
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Old 14th Jan 2020, 8:48 am   #4
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Default Re: Telefunken Operette Radio advice

Thanks for the reply, Ed.

I wouldn't know where to start with it, to be honest, as I'm not sure if any of the valves work / where to source the parts.

Also, I guess this operates off 125V so would need some adjustment to work in the UK (which is possibly why it has been destroyed?).
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Old 14th Jan 2020, 10:32 am   #5
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Default Re: Telefunken Operette Radio advice

This would be a good starting point for repair information:-

https://www.vintage-radio.com/repair...ion/index.html

It would help if you could post a picture of the underside of the chassis so that members can assess the extent of any damage.
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Old 14th Jan 2020, 10:56 am   #6
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Default Re: Telefunken Operette Radio advice

I would fit a self-contained BT module, connected to the existing speaker, and leave the original chassis, valves etc. in situ but disconnected.

That way, you'd have what you currently want, but if you lose interest and want to pass the set on later, someone would still have a viable restoration project.

N.
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Old 14th Jan 2020, 11:37 am   #7
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Default Re: Telefunken Operette Radio advice

I don't think it's particularly rare. Looks like one recently sold for 45
Recent sale
It's an old French radio and if it's been plugged into 230V/240V that won't have done it any good at all.

I would also suggest installing a Bluetooth module connected to the existing speaker and leave the rest untouched.
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Old 14th Jan 2020, 12:12 pm   #8
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Default Re: Telefunken Operette Radio advice

Quote:
Originally Posted by briscaF1 View Post
Also, I guess this is a HCH81 model, circa 1955 (looking on radiomuseum.org)?
HCH81 is a valve type, so far as I know it's a variant of the ECH81 valve (Mixer/Oscillator)

The HCH81 was also used in other Telefunken receivers.

Lawrence.
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Old 14th Jan 2020, 1:48 pm   #9
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Default Re: Telefunken Operette Radio advice

Thanks for all the replies.

I'll take some pics of the underside later but the components are black and the damage may be hard to see.

I'll try the speaker out to see how it sounds as it is. I did think of doing this myself but I wanted it to be stereo - I guess I could always mount a second speaker and cut the board out behind the grill to accommodate.

Thanks
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Old 14th Jan 2020, 4:51 pm   #10
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Default Re: Telefunken Operette Radio advice

Check the valve heaters- if they're intact (they'd likely have survived a short term 2X overcurrent) the rest of any problems may not be too dire. If they're dead, they're a bit obscure and probably not worth the bother.
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Old 14th Jan 2020, 11:30 pm   #11
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Default Re: Telefunken Operette Radio advice

First batch of photos.

You may be able to see some cracks running the length of the capacitors. I think some may be too straight to be cracks but one definitely looks like it has failed.

One of the caps (the one with the green resistor with dots) looks melted at the ends which doesn't look very good, either.

I'm not sure about the heater - what would I be looking for ?
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Old 14th Jan 2020, 11:32 pm   #12
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Default Re: Telefunken Operette Radio advice

Final item.

It is a shame if it has been over-voltaged as it does look pretty clean overall. I've no idea if the valves are functional either.
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Old 15th Jan 2020, 1:07 am   #13
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Default Re: Telefunken Operette Radio advice

That all looks very normal and in good condition to me.

All those black capacitors look as they should do, but are very likely to be internally electrically leaky. Some of them will be in critical positions and the leakage that they have will likely cause damage to valves and transformers if the mains were applied to the set. Some would advise replacing all of them, although I only tend to replace the ones that are likely to cause problems, as I like to keep with originality as much as possible. The valves will probably all be fine, but you never know and it's a risk you take. Certainly you'd need to check the electrical condition of particularly the output transformer before you start doing a lot of work on the set and also check the continuity of the valve heaters.

You'd need to arrange a 125 volt supply for the set if that's what it's supposed to run off.
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Old 15th Jan 2020, 8:33 am   #14
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Default Re: Telefunken Operette Radio advice

Hi, some French sets were designed for 125v but may also have tappings on the mains transformers for up to 220v. Not ideal to connect to 240v but will not do immediate damage if it has happened.
There could well be someone in your area who could quickly check it for you.

Bit of a waste of time adding a second speaker in the hope of getting stereo as they would be far too close together


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Old 15th Jan 2020, 3:53 pm   #15
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Default Re: Telefunken Operette Radio advice

This set has series-wired heaters, so no power transformer. The back mentions a "special adaptor" (probably just a big resistor!) for 220V use.

Much of the Continent used to be wired for 127V phase-neutral, 220V between phases.
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Old 15th Jan 2020, 6:17 pm   #16
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Default Re: Telefunken Operette Radio advice

I'm in the Stafford area if anyone is nearby ? I don't have a variac or an 110V isolation transformer (I presume this set works 110 - 125V)

How much current would one of these sets draw when operating normally ?
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Old 16th Jan 2020, 1:14 am   #17
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Default Re: Telefunken Operette Radio advice

Less than half an amp at 120V.
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