NAD 2140 Problem

Aquarium · 27th January 2007, 09:09 PM

I have a NAD 2140 Power Amp that started giving me strange problems.It blew a couple of it's 3.15 Amp fuses on the PCB after distorting sound started coming from the left channel only.I replaced all 4 3.15 Amp fuses and it seems fine powering up but the noticeable distortion coming from the left channel is still present.Any help or ideas would be appreciated?

es44 · 27th January 2007, 09:45 PM

Most likely it's the driver or output transistors that's blown. If you look at the schematics, the 3.14A fuses are sitting to ( try to )protect those. They will blow again if you krank it up a bit.
Oh yeah, if you don't have the schematic, then drop me a PM, then i'll send it to you.

Good luck
Ebbe

Aquarium · 28th January 2007, 12:05 AM

Thanks,I have that schematic already.I have replaced all fuses on the PCB and I have the amp sitting on with a multi-meter attached to the speaker output measuring the DC from time to time.It seems to have stabilised around 4mv each side which is O.K. I will have to listen again I guess.Can I just replace the left channel output transistors and hope for the best?

es44 · 28th January 2007, 08:38 AM

Well, maybe i'm a litlle too fast to call them dead. It doesn't sound too bad with that kind of dc-balance.
Maybe it's just a coincidence that the fuses blew. Maybe it could be some of the capacitors beginning to dry out ?.
It's a little bit hard to guess without further measurements. A scope and a ESR-meter would be a great help.

Aquarium · 28th January 2007, 06:13 PM

Yes,I hooked up a radio to further investigate and the DC in the left channel shoots right up when under load with quite wide fluctuations,the right channel is o.k.Time for the shop I think.

27th January 2007, 09:09 PM	#1
Aquarium diyAudio Member Join Date: Jun 2004 Location: Adelaide Australia	NAD 2140 Problem I have a NAD 2140 Power Amp that started giving me strange problems.It blew a couple of it's 3.15 Amp fuses on the PCB after distorting sound started coming from the left channel only.I replaced all 4 3.15 Amp fuses and it seems fine powering up but the noticeable distortion coming from the left channel is still present.Any help or ideas would be appreciated?

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27th January 2007, 09:45 PM	#2
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	Most likely it's the driver or output transistors that's blown. If you look at the schematics, the 3.14A fuses are sitting to ( try to )protect those. They will blow again if you krank it up a bit. Oh yeah, if you don't have the schematic, then drop me a PM, then i'll send it to you. Good luck Ebbe

28th January 2007, 12:05 AM	#3
Aquarium diyAudio Member Join Date: Jun 2004 Location: Adelaide Australia	Thanks,I have that schematic already.I have replaced all fuses on the PCB and I have the amp sitting on with a multi-meter attached to the speaker output measuring the DC from time to time.It seems to have stabilised around 4mv each side which is O.K. I will have to listen again I guess.Can I just replace the left channel output transistors and hope for the best?

28th January 2007, 08:38 AM	#4
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	Well, maybe i'm a litlle too fast to call them dead. It doesn't sound too bad with that kind of dc-balance. Maybe it's just a coincidence that the fuses blew. Maybe it could be some of the capacitors beginning to dry out ?. It's a little bit hard to guess without further measurements. A scope and a ESR-meter would be a great help.

28th January 2007, 06:13 PM	#5
Aquarium diyAudio Member Join Date: Jun 2004 Location: Adelaide Australia	Yes,I hooked up a radio to further investigate and the DC in the left channel shoots right up when under load with quite wide fluctuations,the right channel is o.k.Time for the shop I think.

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