Question about NAD C320 2-Channel Amplifier

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Right side speaker input don't work

I have a Marantz 60's model 2230. I was listening to it one day and the right side went out. I smelled something burning. If you turn the volume most of the way up, you can hear a little sound. This is a family heirloom, please help!! Thanks in advance, Jason

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  • Jsonp Feb 02, 2009

    The left side works just fine. Other than that I don't know how else to troubleshoot it.

  • Jsonp Feb 03, 2009

    Thanks alot Dan!!! I found the burned resistor last night and replaced it. When I turned the unit on the same resistor wanted to burn up also. I learned alot about resistors online last night. Just general knowledge. I'm sure there is more I need to learn. I do have a multimeter and I can solder. I'm sure I can do the repair but I need guidence. What can you tell me about output transistors that could help me? Where do you begin testing with the multimeter?


  • Jsonp Feb 03, 2009

    Asheville, N.C.

  • Dick
    Dick May 11, 2010

    There is no way to tell what is wrong with it from that description. I can tell you it isn't something you can fix yourself unless you are skilled with a multimeter, have the schematic, and can read a schematic. But if you had those three things covered, you wouldn't be here.

    Good luck


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There are a number of possibilities that can cause this. Since you smelled some burning, I would suspect that the output transistors on the right side have shorted. This can sometimes cause a resistor to burn before that section is turned off. This is a relatively simple repair for anyone familiar with those units. I have rebuilt a number of these over the years and can tell you that the repair is worth the expense. You can figure on $25-$40 in parts plus the local labor rate for the total cost.

If you have a multimeter and can solder, you may be able to repair this. This is not the easiest unit to access however, so if you are not experienced, I would not start here.

Keep me posted.

Posted on Feb 03, 2009

  • ABRsvcs Feb 03, 2009

    The output transistors are the large silver parts that are roughly oval. The best way to resolve this is to A/B the 2 sides. Remove the output transistors from both sides (mark the ones from the bad side). With the outputs removed, you should be able to power up the unit without generating smoke. If so, carefully take voltage measurements on both sides to determine where things go bad. Its hard to describe the steps as I have been doing this for years and most of the checks are habit.

    Where are you located?



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