Restoring a Gecophone induction speaker.

[Mr Etronic]

Restoring the above. Hate to bin things that have lasted this long.
Case is easy.
Slight tear in speaker, easy enough.
I'm getting infinite resistance across the terminals. I take it the coil has gone or I would get something?
If I put a 9v battery across a speaker this big, will it move it?
Suns out lol but more fun doing this.

[Ed_Dinning]

Hi, looks like the coil (which will be similar to those fitted to headphones) has gone OC. It is many turns of fine wire so fiddly to rewind, but do-able.
The magnets may also have weakened with time, but can have a modern, ferrite high power magnet fitted to assist them.

Ed

[lesmw0sec]

Yes - they are normally fairly easy to rewind if you don't mind fiddling with very fine wire! Regarding the battery test, you won't detect much visible movement, but should get a well audible click.

[Mr Etronic]

Tried a 9v battery on this speaker.
It has terminals labelled high and low.
On low I get a crack.
On high nothing.
Why a high and low, normally just two terminals?

[Station X]

Possibly to match different impedances. These speakers were generally wired in the anode circuit of the output valve.

I assume only one of the windings is open circuit.

[Mr Etronic]

Originally Posted by Station X

Possibly to match different impedances. These speakers were generally wired in the anode circuit of the output valve.

I assume only one of the windings is open circuit.

Well the low seems open and the high seems open.
I get a slight crack across the low which I assume is the voltage from the voltmeter to test continuity.

If the low is giving a slight crack on the speaker, shouldn't I get a slight resistance on it? Not showing it is open?:

[Station X]

I'm not familiar with your meter, but it only has a single ohms setting on the knob. There's also a range button. If you press this, possibly several times, does it switch ranges and perhaps show something other than an over range indication ie 0L?

It's also been pointed out in the forums that DMM's may have problems mesuring inductive loads, but it's not a problem I've come across myself.

[Station X]

Just had a look at the manual. In addition to auto-ranging, there are six resistance ranges to choose from going up to 60M.

[Mr Etronic]

Manual...really lol. So thats why the is no switch its auto. Is the manual online?

[Station X]

Here:-

https://d3gqasl9vmjfd8.cloudfront.ne...2477ad9b5e.pdf

What range were you using when checking the windings?

[Mr Etronic]

You nailed it. A new meter came yesterday had it set wrong.
Having set it right....
low=1.028KΩ
Hi=open
So it seems the coil is ok.
Many thanks for that.
So repair that ripp and it may be ok. You saved me a lot of work cheers.

[Mr Etronic]

Sorry I confused your earlier post about range. But sorted in the end...

[Ed_Dinning]

Hi it looks like it has a transformer fitted from the pic in post 4. so it could be used with an external transformer if your set was connected to the high input (or rewind the transformer, not quite so fiddly as the LS coil)

Ed

[Silicon]

If you decide to take the 'magnet' apart you may weaken it if you don't use a 'keeper' and the proper procedure.

Others will know a lot more about this aspect than me.

[Mr Etronic]

Roger that Silicon....If I can I'll leave well alone.


This was sent by a gentleman.

"The one sort of windings is to generate the magnetic field instead of a permanent magnet. It is also used in the circuit as a smoothing choke. The second windings are for the speaker. If you look at the speaker and the two windings it should be obvious which is which."

Would this be specifically for a particular radio with 4 outputs?

[Station X]

Originally Posted by Mr Etronic

This was sent by a gentlman.
"The one srt of windings id to generate the magnetic field instead of a permanent magnet. It is also used in the circuit as a smoothing choke. The second windings are for the speaker. If you look at the speaker and the two windings it should be obvious which is which."

Would this be specifically for a particular radio with 4 outputs?

That doesn't sound right to me. You can clearly see the permanent magnets.

Try the working winding on a headphone socket (MP3 player etc.) it may work a treat.

[Mr Etronic]

Originally Posted by Station X

Possibly to match different impedances. These speakers were generally wired in the anode circuit of the output valve.

I assume only one of the windings is open circuit.

This sounded a better explanation.