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Tannoy MG12R repair

Mike1965

pfm Member
Hello, this is my first post. Back in the 80's I bought a pair of Tannoy Devon's which are sadly long gone. Too much browsing on forums have brought me back to Tannoy again and I now have two MG12R's.
Unfortunately one of the drivers has a collapsed spider but I have a good condition used cone supplied by Lockwood. I have carefully removed the old cone and there appears to be corrosion on on the horn. How do I fix this? I don't want to damage anything. Thanks for your help and advice.
 
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While you have the cone out its a good time to clean the magnet gap. Use nothing more sticky than the sticky bit on a postit note(s), fold and with sticky side out wipe around the gap, do this several times with numerous post-its until the tacky bit comes out clear. Now using masking tape seal off over the gap to stop any debris falling in.
DO NOT use any wire wool to clean the horn throat.
Try Silvo polishing cotton -its only moistened so no danger of any polish running down the horn throat-it may, if you're lucky, buff off all the surface marks.
If you have proper rust in there then I'd be inclined to brush Rust stop/eater on it to prevent it getting worse-the down side is you must be careful not to get it down the phase plug and it'll turn the rust spots black.
I've only once come across rust so bad as to require Rust eater but once done and behind the dustcap it didn't matter.
 
Thanks Cooky, another question is how do I remove the dustcap from the used cone so I can line it up properly, I read somewhere that I need a shim to do this?
 
Thanks Cooky, another question is how do I remove the dustcap from the used cone so I can line it up properly, I read somewhere that I need a shim to do this?
Here's how I do it, none destructive and without needing shims; The spider has 4 bolt/nuts that allow for alignment. Position the cone so it moves freely(and the leads line up with the plug socket!) then finger tighten the 4 spider nuts, clamp the surround edges down then fine adjust free movement using the 4 spider bolts/ring.
Removal of dustcaps is never pretty and heavily dependent on the glue they've used so I dont do it.
Or send it to Nick at Lockwood(its their cone after all) to do it.
 
Thanks again for your help Cooky, I will try that tomorrow. I'm nervous about sending the drive unit away so if I can do it myself all the better.
 
Firstly the magnetic gap is cleaned out and the pepperpot has cleaned up a bit but other than that things are not going well. One of the leadout wires on the second hand cone is too short to reach the solder tag on the chassis and a lot of the screws on the alloy channels won't tighten up to the chassis. Getting depressed with this already!! What are the chances of buying a single LSU/HF/12G/RS?
 
There's a nack to aligning the alloy channels, I screw into the end holes of each one first, sometimes it helps if you remove the foam gaskets so you can see the screw ends through the holes. Post a pic of the replacement diaphragm to show the leads.
 
I already removed the foams and tried putting the end screws in first, maybe if I can use short bolts that don't protrude beyond the rear of the chassis that would be a solution. I'm at work at the moment so I will post a pic of the leads later when I get home. They have been cut rather than desoldered. One is long enough to just reach but the other would be stretched to reach the tag.
 
With regard to the tinsel lead do I just solder a piece on to make it long enough? Never done this before so I am clueless but I can follow instructions!
 


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