The circuit is very similar to the output stage of the Sony XM-D---P5 amps. The audio circuit on page 2 of the PDF file below shows you basically what you have.
http://www.bcae1.com/temp/xmd400p5schem.pdf
http://www.bcae1.com/temp/xmd400p5schem.pdf
Here is the thread I started for a 421D. May add some insight or just waste your time!
http://www.diyaudio.com/forums/car-audio/152275-mtx-421d-issues.html
http://www.diyaudio.com/forums/car-audio/152275-mtx-421d-issues.html
if its the big large amp, i think the last one i worked on was a 6500D. it had similar issues, one shorted output, blown gate resistor, and all 8 power supply transistors were blown.
I used a 73343 to replace the 73335, which are the same thing, except the RDS(on) of the 43 is much lower, making it more efficiant, less heat. worked better.
I got away with replacing the single output in that one also, and it worked fine. no issues out of that amp. just this stupid amp i got here now....
I used a 73343 to replace the 73335, which are the same thing, except the RDS(on) of the 43 is much lower, making it more efficiant, less heat. worked better.
I got away with replacing the single output in that one also, and it worked fine. no issues out of that amp. just this stupid amp i got here now....
Here are pictures of the amp (after mosfets shorted again and blew its resistors)
http://0ki.info/uploads/d3e2801ffd.jpg
http://0ki.info/uploads/fc16338aeb.jpg
http://0ki.info/uploads/d3e2801ffd.jpg
http://0ki.info/uploads/fc16338aeb.jpg
<snip> do the caps look like they need changed?
They look like they got real hot, and the tops appear to be bulging which to me signals a need for immediate replacement.
It looks just like a 421D that I have. I marked the pic with the parts that were bad on mine. The three caps on mine were bulged and the two smaller ones that flank them were blown off the board. The opamp was the main cause of my output problems.
cory
cory
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