scratchy voice coil

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14 years 7 months ago #7507 by b.p.sound
scratchy voice coil was created by b.p.sound
I have found 2 of my JBL 12" 2206 drivers that have not been used for 2 months very scratchy just like a burnted out voice coil. Checked resistance and found 1 ok and the other open circuit. I stripped the open circuit on only to find the voice coil in perfect condition and resistance now ok. Under closer inspection I have noticed a lot of corrosion in the gap where the voice coil slides in. this I put down to moisture...... Going back to the other driver I removed the dust cap and found more of this corrosion. I have run the driver up and all seems fine but wondered what to do about the corrosion ? ? ? Idears........

1) Spray some WD40 sround the voice coil and then some sort of lubricant (no funny comments please)

2) Leave it and hope the heat burnes off the corrosion

What do you guys think

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14 years 7 months ago #7508 by nickyburnell
Replied by nickyburnell on topic scratchy voice coil
Stop leaving them in the garden :lol:

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14 years 7 months ago #7509 by Tony Wilkes
Replied by Tony Wilkes on topic scratchy voice coil
No chance that the heat will get rid of the corrosion, in fact corrosion loves heat as does any chemical reaction. It is just the reaction of moisture on the steel after the protective coating (normally zinc) has broken down. Even the zinc coating corrodes and you will often find that the surface has a greyish dust on it.

I cannot see WD40 doing any harm but keep it away from any part that may have been glued or any cloth or paper component. The only real long term solution is to stop it happening in the first place by trying to keep the boxes in a warmish dry place and also trying not to suddenly put cold boxes into a warm environment, impossible though that usually is.

Tony

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14 years 7 months ago #7510 by b.p.sound
Replied by b.p.sound on topic scratchy voice coil
Thanks Tony.
The driver I did strip has something rough on the outside of the coil (corrosion) as it is stripped and usless now I rubbed some fine wet/dry and it soon com off and is smooth but if I remember correctly there is a fine clear varnish/wax layer or something so I would think this will soon corrode again. But that was the outside so you can't get in there with the driver built so it don't matter. I also found one of my 2206's open circuit buy when testing it fully found a break in the tail from the connector to the voice coil. the break was... As it gose through the paper cone so I melted the black super glue stuff pulled the flat ribbon strip up a bit, cleaned and resoldered the braded tail to it. Job done just need to get some dust caps now but works perfectly. that strip is very hard to solder to even after cleaning it up. any tips on soldering to this material. what is it made of ?

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14 years 7 months ago #7511 by Tony Wilkes
Replied by Tony Wilkes on topic scratchy voice coil
I thought it was just copper, are you sure you cleaned all of the insulating varnish off? To be honest I used to do loads of repairs on drivers back in the 70s 80s but leave them alone now and get the pro's to do it.

Tony

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