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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 2nd Jun 2020, 5:47 pm   #1
g0hze snowy
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Default Grundig 3086

evening gents
my latest purchase to renovate turned out to be very poorly packed and arrived with the case split at it's seams, so before I spent money on getting it repaired I thought I have a look at it's internals.
Replaced missing mains fuse ( should have told me something not quite right!) and fired it up, I was rewarded with dial lamps and a couple of bottles started to glow, then came the smoke from the mains transformer, a NETZTRAFO 9078-063, not good, I was about to save the bottles and scrap it as the front glass panel with the frequency readout printed on it was also broken.

Now I have a number mains transformers removed from old NIXIE pieces of defunct equipment (I had a spell of making NIXIE clocks!, sad I know ha ha), these have the 6.3v heater winding and a low current 230v output.

so my question is this, scrap it or try to use a surplus transformer.

over to you knowledgeable gents, your opinions, as always, appreciated

Snowy
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Old 2nd Jun 2020, 6:38 pm   #2
vidjoman
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Default Re: Grundig 3086

I would have rejected it as damaged and got the money back.
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Old 2nd Jun 2020, 6:49 pm   #3
g0hze snowy
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Default Re: Grundig 3086

went down that path, I was refunded by eBay but it meant that the seller got away with it, oh well live and learn.
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Old 2nd Jun 2020, 8:21 pm   #4
Ed_Dinning
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Default Re: Grundig 3086

Nothing to loose then !
You may find that your nixie transformers are a lower current rating than the typical 50-80mA used by this type of radio.

Ed
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Old 2nd Jun 2020, 9:06 pm   #5
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Default Re: Grundig 3086

Hi Ed, thanks for that info, I was just going to total up the valve heater currents to see if it would have done, you saved me doing that, if all else fails at least I have some valves, untested of course.
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Old 2nd Jun 2020, 9:26 pm   #6
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Default Re: Grundig 3086

Have you actually confirmed that the TX is dead as in internal failure and not just being overloaded by a short on one or more of its secondaries?
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Old 2nd Jun 2020, 9:48 pm   #7
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Default Re: Grundig 3086

Hello,

as far as I remember this model has got the twin EL 95 push-pull amplifier and kind of an early "Wunschklang" equalizer. Somewhere in my attic there must be such a set. I wonder if I might have an extra mains transformer, must have a look then.

Regards, Joe
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Old 2nd Jun 2020, 9:56 pm   #8
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Default Re: Grundig 3086

Seems a shame to scrap it though, 3086 - is that the one with the push/pull output?
Definitely the transformer, still does it disconnected?, just thinking the usual shorted smoothing caps ect.
Steve.
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Old 2nd Jun 2020, 10:08 pm   #9
g0hze snowy
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Default Re: Grundig 3086

Hi Joe and Steve
Thanks for your update, you are both right it does indeed 2 x el95 bottles as audio output
Going to check the main smoothing cap tomorrow, I have a replacement.
I totalled up the heater current and included the 2 x bulbs, just a whisker under 4 amps ( unless I have got it wrong).
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Old 3rd Jun 2020, 1:19 am   #10
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Default Re: Grundig 3086

The transformer may not be burnt out. You say you had valve heaters, so it could well be a short on the HT line somewhere. Disconnect the supply from the transformer to the rectifier and see what happens.
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Old 3rd Jun 2020, 8:37 am   #11
g0hze snowy
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Default Re: Grundig 3086

Thanks Techman, I am going to do that today although I wonder if it is worth it considering the amount of damage to the case, display etc.
One saving grace seems to be that someone else has been inside and changed a number of 'R's and a few 'C's.
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Old 3rd Jun 2020, 12:13 pm   #12
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Default Re: Grundig 3086

Yes, I think it is worth it. It will tell you what the state of play is with the other main components such as the valves and the mains and output transformers. If you can easily get it to a stage where you have sound and reception, at least you'll have a known usable set of parts. Unfortunately, the broken dial glass is the part that makes this set probably beyond economic full restoration, although if it's not too badly broken, then it could be stuck back together and the set could still be reasonably usable - you could post a picture or two of the damage to get some opinions. If the set had been some random AM only 50s woody, then definitely not worth the bother of getting it working and going the whole hog, but because of what it is, it makes it a bit more worth while. I'm wondering if the previous owner powered it up and already knew there was a fault shorting the mains transformer, hence the missing fuse - are you sure it's set to the correct mains voltage tapping?
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Old 3rd Jun 2020, 7:03 pm   #13
g0hze snowy
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Default Re: Grundig 3086

Techman, some bad news, very many of the resistors had been replaced with a cheap substitute, a great many of them had the end caps off, looked ok but O/C when tested, far too many to justify many hours of work to replace them again.
The main smoothing cap fooled me, as well as the 2 x 50mf caps it also had the 4mf used in the output stages.
I saved the speakers and valves, ( I had already purchased 2 x new EL95,s that will teach me to jump the gun huh).
I did marvel at the clutch mech used to tune VHF or back to MW, I bet that this radio cost a bomb when manufactured in the early 50's.
Then display glass was in 3 or 4 pieces with shards missing.
Thanks to you and the other gents for your help and advice.
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