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.
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.
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.
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.
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.
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?
Sounds like the problem is in the pre-amp section, then. (I assume you meant "...moves to the left channel").
Re-opening this thread as the amp was put to one side to be looked at when I had time. Its now needed.
If the capacitors mentioned above are likely to be the problem can anyone confirm they are the blue ones in clear plastic covers as pictured.
http://i1269.photobucket.com/albums/jj592/soupdragon6/P1050025_zps52b346f1.jpg
http://i1269.photobucket.com/albums/jj592/soupdragon6/P1050024_zps30c06dc8.jpg
If they are, what do I replace them with?. I have a Maplins nearby. A product number would be appreciated. Capacitors - Components | Maplin - The Electronics Specialist
I have a photo which shows writing on the capacitor which with editing can be uploaded if needed.
Thanks.
If the capacitors mentioned above are likely to be the problem can anyone confirm they are the blue ones in clear plastic covers as pictured.
http://i1269.photobucket.com/albums/jj592/soupdragon6/P1050025_zps52b346f1.jpg
http://i1269.photobucket.com/albums/jj592/soupdragon6/P1050024_zps30c06dc8.jpg
If they are, what do I replace them with?. I have a Maplins nearby. A product number would be appreciated. Capacitors - Components | Maplin - The Electronics Specialist
I have a photo which shows writing on the capacitor which with editing can be uploaded if needed.
Thanks.
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Those caps have a safety issue, like any mains connected components. They should be X-type caps now, not those ceramic types originally fitted. Their purpose is to quench the momentary switching arc but this does not produce the same sound as a "pop" or thump on switch on/off. Really, I don't see how this can affect one channel and not the other at all.
I haven't tried experimenting with 3020 wiring but the muting FETS are what should block the typical switching thumps when there is no muting relay, as here. The fact that the fault only appears in one channel tells you that there is a difference in the channels and you do at least have one good channel to check against the other. I would concentrate on the amplifier and leave the 230VAC stuff for later when this problem is sorted.
I haven't tried experimenting with 3020 wiring but the muting FETS are what should block the typical switching thumps when there is no muting relay, as here. The fact that the fault only appears in one channel tells you that there is a difference in the channels and you do at least have one good channel to check against the other. I would concentrate on the amplifier and leave the 230VAC stuff for later when this problem is sorted.
Yes leave the 230 V stuff .... that is not the problem.
Pretty sure the preamp in 2030A do not have muting fets.
Could be a bad electrolytic cap ..... loosing the DC voltage before the PSU voltage for the output section drops, and therefore loosing the bias point before ....
If the preamp had it's own PSU caps for each channel I would have looked ther, but it seems to be common ... therefor I would put my attention to either C513 / C515 or C514 / C516 (depending on chanel). these are 47u /6V3 ... so maybe just change all 4 .....
but only this if you are sure there is no DC oun the preamp output ... and if it is the same when in AUX/TAPE/line as in Phono ....
NAD 3020 SCH Service Manual free download, schematics, eeprom, repair info for electronics
/Baldin
Pretty sure the preamp in 2030A do not have muting fets.
Could be a bad electrolytic cap ..... loosing the DC voltage before the PSU voltage for the output section drops, and therefore loosing the bias point before ....
If the preamp had it's own PSU caps for each channel I would have looked ther, but it seems to be common ... therefor I would put my attention to either C513 / C515 or C514 / C516 (depending on chanel). these are 47u /6V3 ... so maybe just change all 4 .....
but only this if you are sure there is no DC oun the preamp output ... and if it is the same when in AUX/TAPE/line as in Phono ....
NAD 3020 SCH Service Manual free download, schematics, eeprom, repair info for electronics
/Baldin
Thanks for the replies. I was hoping replacing the above would solve it as they are accessible and easy for me to replace. If I remember to turn the balance to the left channel before switching off there is no loud pop so I'm going to connect it and use it as it is.
The reason I've dug this amp out of the cupboard is a recently developed, intermittent fuzzy sound to my nad 314. This is intermittent, on both channels including on headphones. This developed recently after starting to use a pair of Kef Cara speakers which were given to me along with a Marantz PM 26 amp The marantz sounds ok but the balance needs to be 90% to the left to get an even output.
As the marantz had been paired with these speakers from new is it possible they damaged both this and my nad?. They're 4 ohm so should be fine. I removed the main drive units and found no sign of them ever being opened before.
I'm guessing its a coincidence my 314 developed this fault shortly after starting to use these speakers but I don't want to add the 3020 to my growing collection of faulty amps!.
The reason I've dug this amp out of the cupboard is a recently developed, intermittent fuzzy sound to my nad 314. This is intermittent, on both channels including on headphones. This developed recently after starting to use a pair of Kef Cara speakers which were given to me along with a Marantz PM 26 amp The marantz sounds ok but the balance needs to be 90% to the left to get an even output.
As the marantz had been paired with these speakers from new is it possible they damaged both this and my nad?. They're 4 ohm so should be fine. I removed the main drive units and found no sign of them ever being opened before.
I'm guessing its a coincidence my 314 developed this fault shortly after starting to use these speakers but I don't want to add the 3020 to my growing collection of faulty amps!.
4R speakers are obviously a heavier load for a given volume setting than 8R speakers. That may have led to problems sooner with an already duff amplifier but generally speaking - no, speakers won't cause amplifier failures unless they are irredeemably stuffed (damaged voice coils). The amplifiers are specified to drive speakers from 4R upwards and so they should, barring their own faults. The problems stem mainly from the age of the amps and their deteriorating electrolytic capacitors.
It seems you do have a mounting pile of vintage gear that now needs proper repairs and maintenance. It would be wise to have them properly repaired or dispose of them as faulty units - perhaps that is how you received them in the first place.
If the speakers do have a problem, it will most likely be with only one box which you will hear as an obvious sound imbalance or odd noise from one speaker as opposed to one channel output. Simple logic and another pair of speakers will surely sort whether such a problem exists and whether the source is speaker or amplifier and which channel or box.
What you need to do with the 3020A amplifier involves some serious signal tracing, testing and measurement which may be more than you hope to carry out because the dumb shotgun alternative of replacing all possible suspect components is expensive, tedious, possibly dangerous and not guaranteed to work anyway, even if your soldering and component replacement choices are up to it. I would seek pro. repair help or a friend who has successfully sorted this problem in 3030As already. FWIW, there is no schematic or manual for this model I'm aware of. The 3020 manual is linked by Balerit above. For the 314 look here: http://www.hifiengine.com/manual_library/nad/314.shtml
It seems you do have a mounting pile of vintage gear that now needs proper repairs and maintenance. It would be wise to have them properly repaired or dispose of them as faulty units - perhaps that is how you received them in the first place.
If the speakers do have a problem, it will most likely be with only one box which you will hear as an obvious sound imbalance or odd noise from one speaker as opposed to one channel output. Simple logic and another pair of speakers will surely sort whether such a problem exists and whether the source is speaker or amplifier and which channel or box.
What you need to do with the 3020A amplifier involves some serious signal tracing, testing and measurement which may be more than you hope to carry out because the dumb shotgun alternative of replacing all possible suspect components is expensive, tedious, possibly dangerous and not guaranteed to work anyway, even if your soldering and component replacement choices are up to it. I would seek pro. repair help or a friend who has successfully sorted this problem in 3030As already. FWIW, there is no schematic or manual for this model I'm aware of. The 3020 manual is linked by Balerit above. For the 314 look here: http://www.hifiengine.com/manual_library/nad/314.shtml
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Thanks for the advice that the speakers are unlikely to harm. The 314 was bought new but I've used it almost daily for 16 years and owes me nothing. The Marantz and 3020 were both given to me. They're both still usable. I connected the 3020 for a few days recently and was surprised how much I enjoyed listening to it. I forgot to mention the Sansui amp. The second amp I owned which developed an intermittent loss of sound at low volume which is still in a cupboard!. I need a fix or ditch approach but with a large loft things tend to get parked for "later". (Do I really need four turntables?)
Thanks again for your thoughts.
Thanks again for your thoughts.