NAD 3020A Loup pop on switch off

richardmoon · 3rd December 2010, 02:49 PM

I have been given a NAD 3020A which is working well apart from a loud pop through mainly the right channel when I switch it off. This happens at the same volume regardless of volume setting and also happens through headphones when connected. I am currently working round it by plugging a jack plug into the headphone socket on switch off. Is this a common fault which is easy to fix or does it need someone more skilled than me to fix it.

jaycee · 3rd December 2010, 06:11 PM

If you disconnect the "pre out" and "normal in" jumpers, do you still get the pop?

godfrey · 3rd December 2010, 06:54 PM

I'm guessing that there's a relay that's supposed to disconnect the speakers when the amp is switched off (or on) to avoid the "pop". If so, the problem is probably with that relay or the circuit controlling it.

cliffforrest · 3rd December 2010, 07:04 PM

Quote:

Originally Posted by godfrey

I'm guessing that there's a relay that's supposed to disconnect the speakers when the amp is switched off (or on) to avoid the "pop". If so, the problem is probably with that relay or the circuit controlling it.

IF there is a relay (and I can't remember for the 3020A) AND it is only one channel, a welded set of contacts on that channel is the most logical cause.

reddish75 · 3rd December 2010, 10:31 PM

No output relays on the 3020 models i'm afriad and a turn on/off thump is quite normal on these amps.

richardmoon · 4th December 2010, 12:55 PM

Thanks for the replies, I have been around a few 3020's in the past and all have had the start up thump, which I quite like!. However none have had this loud click/pop on switch off. I have disconnected the jumper links and the pop dissapears. I have then connected the right pre amp out to the left normal in. After doing this the pop moves to the right channel.
There is a slight click from the left channel which is only really noticable on headphones and which seems normal, the click from the right channel is the same sound but far louder.

DF96 · 4th December 2010, 01:24 PM

If there is not a mains filter, add a 10nF mains-rated (e.g. X or Y) capacitor across the transformer primary. If such a capacitor is already present, try replacing it. These capacitors are designed to fail-safe, which can mean that their capacitance declines over the years. The aim is to reduce the spark at the mains switch, and also reduce the pulse which is getting picked up somewhere.

fastvideo · 4th December 2010, 02:16 PM

Quote:

Originally Posted by richardmoon

I have been given a NAD 3020A which is working well apart from a loud pop through mainly the right channel when I switch it off. This happens at the same volume regardless of volume setting and also happens through headphones when connected. I am currently working round it by plugging a jack plug into the headphone socket on switch off. Is this a common fault which is easy to fix or does it need someone more skilled than me to fix it.

Quote:

Originally Posted by richardmoon

Thanks for the replies, I have been around a few 3020's in the past and all have had the start up thump, which I quite like!. However none have had this loud click/pop on switch off. I have disconnected the jumper links and the pop dissapears. I have then connected the right pre amp out to the left normal in. After doing this the pop moves to the right channel.
There is a slight click from the left channel which is only really noticable on headphones and which seems normal, the click from the right channel is the same sound but far louder.

From what I understand the pop noise is always on the right channel and happens only when you switch it off, right?
Is this the same circuit with Nad 3020B?

godfrey · 4th December 2010, 02:19 PM

Quote:

Originally Posted by richardmoon

...I have disconnected the jumper links and the pop dissapears. I have then connected the right pre amp out to the left normal in. After doing this the pop moves to the right channel.

Sounds like the problem is in the pre-amp section, then. (I assume you meant "...moves to the left channel").

wazz · 4th December 2010, 08:11 PM

Does that amplifier have a switched mains output for powering other gear, and is anything else powered down with the amplifier? Or does it pop with an unused source input selected at the time of shutdown?

3rd December 2010, 02:49 PM	#1
richardmoon diyAudio Member Join Date: Jan 2009	NAD 3020A Loup pop on switch off I have been given a NAD 3020A which is working well apart from a loud pop through mainly the right channel when I switch it off. This happens at the same volume regardless of volume setting and also happens through headphones when connected. I am currently working round it by plugging a jack plug into the headphone socket on switch off. Is this a common fault which is easy to fix or does it need someone more skilled than me to fix it.

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3rd December 2010, 06:11 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	If you disconnect the "pre out" and "normal in" jumpers, do you still get the pop?

3rd December 2010, 06:54 PM	#3
godfrey diyAudio Member Join Date: Nov 2009 Location: Cape Town	I'm guessing that there's a relay that's supposed to disconnect the speakers when the amp is switched off (or on) to avoid the "pop". If so, the problem is probably with that relay or the circuit controlling it.

3rd December 2010, 10:31 PM	#5
reddish75 diyAudio Member Join Date: Aug 2006	No output relays on the 3020 models i'm afriad and a turn on/off thump is quite normal on these amps.

4th December 2010, 12:55 PM	#6
richardmoon diyAudio Member Join Date: Jan 2009	Thanks for the replies, I have been around a few 3020's in the past and all have had the start up thump, which I quite like!. However none have had this loud click/pop on switch off. I have disconnected the jumper links and the pop dissapears. I have then connected the right pre amp out to the left normal in. After doing this the pop moves to the right channel. There is a slight click from the left channel which is only really noticable on headphones and which seems normal, the click from the right channel is the same sound but far louder.

4th December 2010, 01:24 PM	#7
DF96 diyAudio Member Join Date: May 2007	If there is not a mains filter, add a 10nF mains-rated (e.g. X or Y) capacitor across the transformer primary. If such a capacitor is already present, try replacing it. These capacitors are designed to fail-safe, which can mean that their capacitance declines over the years. The aim is to reduce the spark at the mains switch, and also reduce the pulse which is getting picked up somewhere.

4th December 2010, 08:11 PM	#10
wazz diyAudio Member Join Date: Dec 2010	Does that amplifier have a switched mains output for powering other gear, and is anything else powered down with the amplifier? Or does it pop with an unused source input selected at the time of shutdown?

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