Ron Johnson wrote in message
...
N_Cook wrote:
Perhaps it is chemistry . Bear in mind that the wire is silver and not
copper and the surface area of a squashed wire is more than when it was
round and any corrosion on that surface will have proportionally more
effect
on the thin flats than the bulky round.

The voice coil wire looked like copper because it was under a coppery
brown
lacquer. But, before it disintegrated, the ribbon section was darker
brown
than the round section.
Now if air could get under the lacquer and tarnish the silver to black
copper sulphide, or whatever that blackening is, then that would
explain
it.
Unfortunately none of that section remains as it literally turned to
dust
after photographing it, you could not pick it up even with fingers, it
was
little more than a wraithe.

Are you sure that voice coil isn't aluminium? Some aluminuium v/cs are
copper coated btw.

Ron(UK)


The voice coil remains unaffected, do you know of a simple test for silver v
aluminium ? I would say it looked brighter, more silvery indeed, than
aluminium but I am not familiar with seeing .07 to 0.09 mm diameter Al wire
or silver wire for that matter.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/