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Rick Ruskin Rick Ruskin is offline
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Default Sennheiser mkh405 problem

On 9 Oct 2020 02:18:39 -0000, (Scott Dorsey) wrote:

Rick Ruskin wrote:
I fired up my pair today and found 1 is working while the other is has
a very distorted output. I know these mics tend to drift out of spec
but might it be something else and is there a way for a non-tech to
troubleshoot it? Right now I'm leaving it powered up to see if it
might correct itself but I'm not holding my breath.


1. Check the diaphragm. Is it damaged? Shine a flashlight and make sure the
surface is flat. The capsules on these don't go bad easily but if they do
I don't think anyone can reskin them.

2. There are three or four small electrolytics in there. Do they test good or
are they leaky? Use an ESR tester on them. My personal inclination about
electrolytics of that age is to replace them rather than testing them, but
it's very tight in there and you will need a precision solder removal tool.
Changing them is not for the faint of heart.

Beyond that point you're going to be checking the RF stuff. I have seen the
silver mica caps go bad and the oscillator frequency drift way off once, but
I can't imagine it's that common a failure. There really isn't that much
to go wrong in these; they are not that complicated, but they are RF systems
so they require having your head in a different place than conventional
audio gear.
--scott



Thanks. I'll contact Sennhieser tomorrow to see if they still service
this unit. The caps have been obsolete for decades now but I suspect
something else has bit the dust.




Rick Ruskin
Lion Dog Music - Seattle, WA
http://liondogmusic.com

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