1940s radio - servicing and converting gramophone input socket to modern input

Tech, TV, Mobile, Internet and Geek Corner
1
I recently found a lovely and apparently functional 1940s radio (made in Solothurn) in a Brocki.

It has an older style input jack for a gramophone and I was hoping to either buy a converter that would plug into that, so I could use a modern input line, or to find somewhere that could convert it to a modern input directly.

http://www.radiomuseum.org/r/autopho...pion_42.html#b

Does anyone know somewhere in or near Zürich to convert it (or preferably) sell a converter and maybe give it a service?

Cheers, Ali

2
Seems optimistic, but I hope you can do something; it looks pretty cool.

If all else fails, can you gut it and put a modern speaker inside? Something that'll sound good for its size and fit easily in the case, like a Bose or even a computer speaker.

3
Converting the input line is definitely do-able - there are quite a lot of old sets that I've seen with that done. Either option will probably cost more than the set did, but this is Switzerland.

I'm not going to replace the insides though, I'd really like to get an old and crackly set to play old and crackly music on.

4
Just one question - do you want to use it as a phono input, or line-level (for ipod, laptop etc.)?

It's a pity that you are not from Basel. I'd help you. I love retro audio devices.

5
A fascinating project. I tried to find a better picture of it to work out what connector you need to plug into the radio. I found this : https://www.ricardo.ch/nsf/productde...y/?a=752386672 . Is it yours ?

I guess the required connector could be a quarter inch mono jack plug.

Even if you had the connector, you probably would not be able to connect, say your iPhone directly to it. You'd probably need some sort of matching preamplifier or transformer in between.

6

Hi, it depends what's possible. I've assumed that the current line in would work as a phono input with any other input signal being too strong. If I can find something to step a line level input down to phono level I'd connect that externally.

The input actually looks like banana plugs might work and google threw up this, which I will try.

http://en.wikipedia.org/wiki/Banana_...ug_adapter.JPG

I realise also that the valve(s?) may no longer be functioning. At the moment the set hums pleasantly when turned on but that's it, I don't have the antenna connection so cannot tell if there's no reception or if some part needs replacing. The valve gets pretty hot, if that's a sign it still works I couldn't say.

Thanks for the offer of help Bagnos. Basel's not that far away so if you do want to help then I might take you up on that.

I'll take a few pictures and post them later. Mine's not in as good a state as the museum picture above, for now if the insides still work that's enough.

Cheers,

Ali

7
It's not simply a question of level, but also of equalization.

Phono inputs have equalization that won't work with line input, and vice versa.

Also, an older set may have something other than standard RIAA.

You need to find out what's there, and what you need.

Do you have a schematic?

Tom

8
There is a poor quality circuit diagram on http://www.radiomuseum.org/r/autopho...pion_42.html#b

You have to register to see a better quality one.

I think the OP should register (if he has not already done so) and post the circuit diagram here. I'm also curious, having built, as child built, a valve amplifier.

9
A quick update - the set works, sort of, the sockets at the back connect with banana plugs (invented about 20 years before the radio was made). There is some reception on the radio, beautifully the first thing it picked up was Unfinished Sympathy.

Reception is very poor with the jerry built antenna so I'll try with something more robust.

The line in unfortunately does not work as yet. There's also every 10 seconds a thudding sound which could be a fault in one or more of the valves, like some sort of electrical discharge. Happy to be further informed on that.

The website including the schematics is rather strict on the rules about sharing info, which cannot be enforceable given how old the schema is. They also ask for a lot of info that i'm not so happy to share. I may still sign up at some point.

There are also pictures of my set which for reason appear rotated or upside down when posted here, so I'll put them on flickr or some similar.

Cheers, ali

10
Combing through https://www.google.ch/?gws_rd=ssl#ne...thumping+sound suggests (amongst other things) a breakdown in a power supply capacitor.