NAD C325BEE - burnt components on AMP-SMD-L BOARD

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Hi,

my NAD C325BEE has some burnt components on the AMP-SMD-L BOARD (left channel). See the pics.

The amp was having some problems in the previous 6-12 months like not going into "ON" mode. The LED was going from amber to red but after a few retries the problem went away.

Yesterday, after a burning smell coming out of it, the LED remained amber all the time so I decided to open it and see what's going on.

The thing is that I do not know why this has happened and what to do to fix it. Should I change the whole board or replace parts. The second is a bit difficult as these are smd's and I don't have the proper equipment. I wonder if I can use regular components.

Changing the whole board makes more sense but what if the root of the problem is somewhere else. And I do not know how easy is to find these boards online.

Any help would be appreciated.

(service manual: http://www.hifiengine.com/manual_library/nad/c325bee.shtml)
 

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Hi,
I had similar problem and decided to share my experience.
My c325bee didn't start from the first time. And the behavior of LEDs were very similar. Fortunately nothing was burned :) I looked up different forums and found that these models have poor quality electrolytic caps, and protection circuit would fail because of this. I changed almost all electrolytics on the boards around power supply, preamps and amps, but it did not help, the issue was still there. Btw, the board quality is also very poor. Be careful with soldering iron - it's very easy to overheat it. Then I found that one of the vertical boards gets very hot, if the rear switch is On. The components on both boards looked fine. However voltage readings across the electrolytic caps were different. I decided to replace those smd electrolytics as well. It was not easy to do it but I managed to unsolder them with only one pad broken (board quality is terrible). I found some brownish, resin-like stuff under the caps on the hot board. It looked like the caps were liking (see photo). I assume that the caps on those boards failed because they were exposed to high temperatures for a long time. So, to make long story short, after replacing these caps the amp works as it should.

Hope it helps,
Yury
 

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I also have a 325BEE in the shop with the same symptoms. The NAD C325BEE AMP-SMD-L board gets warm and emits a burnt odor. I replaced the cap next to the overheating resistor with a thru hole part temporarily to test. The unit no longer gets hot, but it still does not power on.

Customer brought in the unit with exploded main capacitors in the power supply. So I had to restore the power PCB before I could do further testing.
 
I also have a 325BEE in the shop with the same symptoms. The NAD C325BEE AMP-SMD-L board gets warm and emits a burnt odor. I replaced the cap next to the overheating resistor with a thru hole part temporarily to test. The unit no longer gets hot, but it still does not power on.

Customer brought in the unit with exploded main capacitors in the power supply. So I had to restore the power PCB before I could do further testing.

I came across this old thread searching for some known issues with the NAD C325BEE. Recently I acquired an "ebay-special" knowing full well what I was buying. I do like NAD designs, but the out-sourced-manufacturing is terrible.

So questions: did you finally replace these caps with SMD form-factor caps? Also, from my search these smd caps are branded YTF (China)...have you any experience of the quality with YTF caps? I've none.

Thanks,
Joe
 
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