Murphy A122

[Andrewausfa]

The speaker wires go in a couple of clips which I think yours may be missing but it all looks something like this when complete.

Andrew

[stephen-niall]

Thanks andrew for that picture,

I spent a while looking for some wires that were free on the chassis.

I have had the radio working & picking up signal, but as i increase tone is gets almost impossible to listen too. Does anyone know what could cause this ?

My main guess would be something with the tone pot & to clean it with contact cleaner, I will be doing that as soon as i get a new bottle. But i'm not 100% sure.

I think one of the valves has gone, as i can twist the glass part (With no force), slightly left and right ... Does anybody know any suppliers of these particular valves, i believe its a Mazda TH-41.

Many Thanks,
Stephen

[mark pirate]

The valve should be ok, as you have had the set working, it will only be the failure of the cement holding the glass to the base, I use masking tape to re-secure the base, Don;t use superglue or the glass may fracture after a while.

Mark

[Nickthedentist]

Originally Posted by stephen-niall

I think one of the valves has gone, as i can twist the glass part (With no force), slightly left and right ...

That's almost normal for a set of this age. The valve may well be working perfectly and continue to do so, unless you wiggle it too much! Don't buy any new valves un-necessarily - they're not cheap, and there are only so many left to go round.

Best advice is to leave well alone, or use Araldite, but not Superglue, as mentioned above.

If you need to remove the valve, always grasp it by the base, never the glass "envelope".

[stephen-niall]

Ah, I will simply take extra care with the valves then.

Currently iI'm gluing the side panels which have de-laminated back together and am removing the rust from the inside surfaces. I will update with pictures in a little while showing what iI've done so far.

[Nickthedentist]

Originally Posted by stephen-niall

And am removing the rust from the inside surfaces.

BTW, never use wire wool for this, as the tiny bits will get everywhere and short the tuning capacitor and wreck the speaker.

I find a green plastic pan scourer with a squirt of WD40 on it, followed by a clean rag with some WD40, and finished off with a clean, dry rag works well for light rust.

Either way, best protect the speaker, either with some cling film, or by carefully removing it and storing elsewhere.

N.

[stephen-niall]

All the bits i removed the rust on i removed from the unit & chassis. The speaker in my unit has had its coil burnt out somehow, so is knackered. I have a substitue one i can use for now, but would eventually like to get an original speaker.

I did use wire wool, but wiped all the dust away with a damp cloth. Most of the rust was surface rust and i was able to remove it by scratching it off with a 'putty knife' .

Cheers,
Stephen

[Nickthedentist]

Next time, you could try car "cutting compound" e.g. from Halfords, which will polish away rust spots without scratching like a putty knife or similar might.

[stephen-niall]

I actually have some rust treatment stuff (Not too sure of the name), and you paint it on & it dries sort of like an epoxy resin, it converts all the rust back to metal. Its really good stuff, and works on really rusty items. but because of the small amount of rust, i didn't feel it was neccesery to use it. Thanks for the cutting compound idea, i'll be sure to keep it in mind.

[Refugee]

The capacitor in series with the tone control may well cause a problem if it is short circuit.
It is C26 on the circuit I showed a few messages back.
It will ruin the tone control pot if it is not replaced.

[stephen-niall]

Ah, Thanks for that. I'll replace that tomorrow if i have a suitable spare.

Stephen