Originally Posted by Jim Land

jetskimatty wrote in
:

I have a mission ms10 subwoofer.
It died a few months ago and since the local engineer looked at it, it
seems that I need a new component for it called a "s53 ami" power
amplifier module.
The company that originally manufactured the board have gone out of
business and I have emailed Hardman Karmon, Jbl and Mission about the
problem and they say I may as well throw it away!!
Can anyone please help me with this as I really don't want to throw it
away!!

If you do some Googling, as I just did, you will find out that you are
not the only person in the world who had this problem with a subwoofer
powered by the S53AMI. The web is full of people whose sub stopped
working when the S53AMI blew. Transistors blew up. A capacitor had a
bad habit of blowing up. When they replaced the S53AMI, the replacement
blew up.

The speaker manufacturers (including JBL and Infinity) and their factory
service centers had lots of problems on their hands with replacing
S53AMIs and making modifications to the circuit to try to make it more
reliable. They finally gave up on repairing units and instead offered
discounts on more recent subwoofer models. And then the S53AMI wasn't
available any more.

There's an interesting discussion thread over at
http://www.diyaudio.com/forums/showthread/t-48627.html where some audio
freaks actually opened the metal can and removed the epoxy encapsulation
of an S64AMI (similar to your S53AMI) so they could trace the circuit and
measure component values. What they found is very discouraging. They
say it's a digital amp, class D, Harris circuit. No heat sinks on the
output transistors. And poor circuit design throughout, making for a
very cheap module to build, but very poor reliability.

In summary, you *don't* want to replace the S53AMI in your subwoofer,
even if you could find one. You want to buy a new, different amplifer to
replace what's in your subwoofer, as another poster has suggested. They
are not that expensive, and will put new life into your subwoofer. So
you don't have to throw it away!