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Old 21st September 2009, 12:30 AM   #1
diyAudio Member
Join Date: Sep 2009
Location: Wisconsin
Default Looking for MTX 421D info

I have a 421D amp that has full +DC rail voltage on the speaker output terminals. C143, C140 and C120 all showed signs of damage, C120 was completey fried. One of the output fets was also shorted. Any ideas on where to start with this?

I wasn't able to find any schematics for MTX amps anywhere, apparently they won't release them. Attached is a pic of the PCB, where is the saw waveform produced?

Any info would be appreciated.
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File Type: jpg DSCN0730.jpg (970.3 KB, 56 views)
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Old 23rd September 2009, 04:20 PM   #2
lee1976 is offline lee1976  Poland
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Join Date: May 2009
Location: 52.740N, 15.230E
The diagram can be a problem, but I would start from checking the output transistors because probably be pierced
Subsequently, the capacitors, which you write and you can see in the picture and check transistors control (driver)

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