Question about NAD C370 2-Channel Amplifier

3 Answers

NAD C370 distortion.

Hi There
The sound from my NAD C370 has just lost quality and is distorted even at very low volumes - I suspect this is the result of a combination of stupid errors by myself today.
I was intending to connect a recorder (hard disc) to the tape 1 out socket (so I could record onto the hard disc).
I had not conected up to the hard disc but I did connect the phonos to the NAD - unfortunately by mistake I think connected to the pre out 2 sockets rather than the Tape 1 out socket and yes I then noticed I had knocked the amp back on while I was grapling around.
Would this have led to my sound problem? and how easy/difficult is it to repar or have repaired. Your advice will be greatly appreciated. Best regards. Nick

Posted by on

  • Nick May 25, 2008

    Hi IrishDruid
    Many thanks for the rapid response.

    As regards the second point(speaker protection relay)- Where would I find the relay and how would I recognise the one which engages shortly after turning the amp on? and what do you mean by 'see audio returns'

    Does the fact that I am asking these types of questions mean that I don't stand a chance of sorting this on my own?
    Many thanks and Best regards, Nick

  • Nick May 25, 2008

    Again many thanks IrishDruid,
    I tend to agree that from what you are saying it seems I should take it in to a NAD service centre...
    Would just like to see if there are any other thoughts out there - just so I can offer all the possibilities to the tecnicians and not appear too green. Best wishes, Nick

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3 Answers

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  • Master
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As a way of explanation of what occurred here, let me describe the circuits involved.

1) By connecting the tape output to the pre-amp in, you basically connected up a loop.
2) The pre-amp out is isolated from the output amplifier so the problem you are having is not in the output amp, but in the pre-amp section. The protection relay does not figure in here. IF it did, you would have no sound at all.
3) The NAD designs are such that the pre-amp section has a number of feedback loops to improve sounds quality and are not the easiest to repair without previous experience.

Bottom line here is that the parts cost for this repair will be in the $10-$20 range only. It is this high mainly because of the feedback design which for overall quality concerns requires that more parts be replaced not because they have failed, but because they have been stressed because of the failed parts.

Dan

Posted on Jun 06, 2008

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  • Master
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Well..my input on this, is that ID, who's really talented at this, has provided a complete review and helpful solution.

i'd give him the fixya back, if I were you

Posted on May 25, 2008

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  • Master
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It looks like you may shorted some part of the audio circuitry, Most likely you will have to replace the entire board (easier option).

If you can find a replacement board, it shouldn't be too hard to replace, if you have had prior experience with electronics. However,i think it is best you let an experienced electronics repair guy do this for you.

hope that helps..

Posted on May 25, 2008

  • Swilin Sampson
    Swilin Sampson May 25, 2008

    Found this possible solution as well by robotek:

    It could also be an issue of a faulty speaker protection relay. Gently tap the relay(the one that engages shortly after turning the amp
    on) when the fault is occurring and see audio returns. This should
    ascertain the problem. Replace it if it is a sealed type, or if it has
    a "lid" you can get off, burnish the contacts with a white business
    card, and give it a spray with contact cleaner/lubricant.

  • Swilin Sampson
    Swilin Sampson May 25, 2008

    'Audio returns' means the quality of the audio output (distortion/static, etc)

    Unfortunately, I do not have an image of the relay in question, and it is quite difficult to explain...
    Perhaps it would be best if you got a technician to look at this, mentioning the relay as well. He should be able to figure that out.

    I wouldn't recommend you opening up your device if you are unsure, as there is a possibility of a severe shock/fire hazard as well..

    You may have to spend a little, but in my honest opinion, this would be the safest/best way to go about resolving this issue..


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