Most
long-time audiophiles would be familiar with the issue of
speaker surrounds going crumbly and falling to bits but few
really understand why this occurs. Decomposition of rubber
components does not just affect speakers however. Many amplifiers
use rubber mounts for components like power transformers.
This Audio Research solid state amp provides us with one extremely
mucky example!
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The
unit had been stored face up, resting on its rear handles.
The transformer is mounted just behind the front panel with
a big slab of vulcanised rubber in between. The rubber was
well on its way to reverting to a liquefied state and gravity
was helping it ooze all the way from the front to the back
as can be seen from this shot of the inner surface of the
bottom panel.
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It
was clear from the start that saving this amp would involve
pulling it all apart... but the more it came apart, the worse
it looked. This is very thick, nasty, sticky, smelly goo that
turns anything it touches black. Its consistency is somewhere
between that of hot tar and cold treacle!
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The
sub-panel had to be prised away from the transformer to reveal
the source of this evil muck. The cleaning effort was slow
and painstaking and involved a lot of cleaning materials and
chemicals.
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An hour
or so later and we're almost down to the metal but there's at
least another roll of paper towel and sticky goo remover to
go before the transformer can be re-mounted. |
Vulcanisation
is a process that produces tough rubbers for all sorts of
industrial and automotive applications. It involves the formation
of molecular bonds between latex and sulphur to form very
long chain polymers. Sooner or later however, these bonds
will start to break down thanks to either oxidisation or bacterial
action or both. How long this takes is not very predictable
and no doubt environmental factors would also affect the rate
of degradation. This is precisely the same mechanism that
causes speaker surrounds to break down. Bottom line? If you
see any rubber bits on your gear getting a bit soft and sticky,
don't delay getting it checked out because it's a lot easier
to remove old rubbers while they're still in one piece.
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