[Ron C[_2_]]

On 12/2/2018 6:55 AM, Phil Allison wrote:
Ron C wrote:



Have you checked whether there's a break in the inteqrnal wiring?

Peace,
Paul


Yes, I've checked .. no problems there.


** Hang on - you say the internal wiring is all OK ( not corroded) and the mics are both dead ? Have you checked the voice coil with a DMM ?? A reading at the XLR of about 250 ohms shows it is intact.


Heck, the mic's are 20++ years old,


** Still within the useful lifespan for Shure vocal mics that get low usage.


so I guess
I've gotten my money's worth out of them.


** I disagree and think the foam wind sock disintegration is a separate issue to the mics going silent.


I understand that electrets can become depolorized
but never thought dynamics would/could go bad just
sitting in a box. Live and learn.


** Fine copper wire, as normally used for voice coils on mic diaphragms, corrodes under damp conditions and develops opens.

However, Shure mics like the SM57 & SM58 use much thicker wire for the voice coils followed by a step up transformer which goes a long way to extending these mics lives.



... Phil


Damn, I hadn't thought to check for an open voice coil.
Yep, they both measure as open. Corrosion of the super
fine wire is quite the logical explanation.

Thanks.
--
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Later...
Ron Capik
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