On Sat, 09 Apr 2011 00:43:51 +0100, Gareth Magennis wrote:

"Meat Plow" wrote in message
news
On Sat, 09 Apr 2011 00:12:23 +0100, Gareth Magennis wrote:

"Meat Plow" wrote in message
news On Fri, 08 Apr 2011 10:17:06 +0100, Gareth Magennis wrote:

Interestingly the customer said that the amp went DC and fried his
speaker - the amp has no relay or DC protection. My little bit or
research so far indicates that dv/dt failure in industrial motor
applications can be down to pulling the power cable off a stalled
motor, zapping the gate/substrate connection in a nanosecond. Might
this also apply to a faulty speaker in this kind of audio amp which
burns short then eventually self disconnects?

I also understand extremely electrically noisy environments can also
induce this failure mode. The customer is daisy chaining this amp
with another one via the FX send, I'm wondering if this has any
chance of being the cause of the failure.

Slaving another amp via the send isn't likely but a failing speaker
or poorly wired/connected load might be the reason.




Check this out, if just for educational purposes. Quite interesting.

http://www.4qd.co.uk/serv/MOSFETfail.html



Gareth.

Mostly pertaining to motor control applications. My experience is
limited to audio applications. Some similarities exist thought. Still a
good read for failure modes.




Isn't a speaker a motor?



Gareth.

It can be perceived as a sound motor.



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