NAD 3020i Transformer noise

JCHel

Member
2016-03-21 7:55 pm
Hi People,

I am a new user on the forums with limited knowledge so standard school yard appeals of mercy apply. I'll keep it brief...


NAD 3020i just purchased.

Amp sounds good but has considerable transformer noise at all times. Its not sent to the speakers but merely emanating from the unit itself and loud enough to be annoying in a silent room.

I have found various comments about this issue with these units but can't find solutions.

Much appreciated if anyone has any ideas to eliminate this problem.

Cheers and keep up the good fight!

JCHel

p.s. mp3 of the noise recorded on iPhone attached for your listening pleasure.
 

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Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
A lot of 3020 amps, not just 3020i series, developed loose transformer laminations. I don't think any late series models are bolted together though, which means painstakingly packing the laminations tighter in the folded steel frame, ensuring the shielding around it doesn't also rattle or replacing the transformer. I have read here, in other threads on this problem, that the power supply caps and rectifier condition affect this buzzing too.

[IMGDEAD]http://picdb.thaimisc.com/u/usedlism/5957.jpg[/IMGDEAD]
 

JCHel

Member
2016-03-21 7:55 pm
Thanks a lot for the suggestions chaps.
I've taken the advice and straightened out the bottom plate... but alas no difference.

Any more tips? What about this mention of replacing per supply caps and rectifier? Anyone know about that?

Cheers all.
JCHel
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
As suggested in #3, tighten the transformer frame on the laminations or replace it with a transformer from an older wreck. You may not have the skill to do this work so replacement may be your only option.
In any case, you should replace the main smoothing caps. (the 2 big caps right in centre) They could be as old as the amplifier and really needing replacement. I doubt the rectifier has failed but it is a remote possibility. If these are bad, the power supply could easily become noisy too, as I understand happens with other 3020 models too.
 

JCHel

Member
2016-03-21 7:55 pm
As suggested in #3, tighten the transformer frame on the laminations or replace it with a transformer from an older wreck. You may not have the skill to do this work so replacement may be your only option.
In any case, you should replace the main smoothing caps. (the 2 big caps right in centre) They could be as old as the amplifier and really needing replacement. I doubt the rectifier has failed but it is a remote possibility. If these are bad, the power supply could easily become noisy too, as I understand happens with other 3020 models too.
Many thanks Ian.
Any opinion on brand etc for the caps? Testing the rectifier is beyond my knowledge but replacing the caps is certainly within easy reach.

Cheers,
JCHel
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
Don't waste time and money on fancy brands/grades of caps. This a NAD product built with low cost parts as cheaply as possible. Only electrolytic (polarized) type caps are a problem and I suggest you simply fit good commercial quality parts that are widely available. There are many quality criteria for the main smoothing caps and each manufacturer has different mixes of ripple current rating, temperature rating, lifetime rating, to name the important ones.

Generally, you need to check pin spacing so that they fit securely, flat on the board without stress on the pins. Modern caps in larger values are standard snap-in types with 10 mm spacing - not certain what is fitted in that model so check and also check diameter and height for an easy fit. New caps are a lot smaller so you can fit larger values - up to 10,000 uF max. but no more or there will be stress on the power switch and other components which are not robust. Always use the same or higher voltage rating to that marked.

The prime issue is that replacements are fresh stock from sellers with good turnover. Panasonic TSHA is popular and good, then Nichicon, Rubycon, Elna, Nippon Chemicon, Epcos, Samhwa all have good products too. Don't buy house brands or from unknown Ebay sellers - many sell fakes or old stock, don't specify the parts sufficiently or even know much about them.
 
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JCHel

Member
2016-03-21 7:55 pm
Don't waste time and money on fancy brands/grades of caps. This a NAD product built with low cost parts as cheaply as possible. Only electrolytic (polarized) type caps are a problem and I suggest you simply fit good commercial quality parts that are widely available. There are many quality criteria for the main smoothing caps and each manufacturer has different mixes of ripple current rating, temperature rating, lifetime rating, to name the important ones.

Generally, you need to check pin spacing so that they fit securely, flat on the board without stress on the pins. Modern caps in larger values are standard snap-in types with 10 mm spacing - not certain what is fitted in that model so check and also check diameter and height for an easy fit. New caps are a lot smaller so you can fit larger values - up to 10,000 uF max. but no more or there will be stress on the power switch and other components which are not robust. Always use the same or higher voltage rating to that marked.

The prime issue is that replacements are fresh stock from sellers with good turnover. Panasonic TSHA is popular and good, then Nichicon, Rubycon, Elna, Nippon Chemicon, Epcos, Samhwa all have good products too. Don't buy house brands or from unknown Ebay sellers - many sell fakes or old stock, don't specify the parts sufficiently or even know much about them.
Great. Thanks for the info Ian.

This should do the trick then?

PANASONIC ELECTRONIC COMPONENTS - ECOS1VA682BA - Electrolytic Capacitor, TS-HA Series, 6800 µF, ± 20%, 35 V, 22 mm, 0.061 ohm | CPC UK

JCHel
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
That looks like a choice I would make. Unfortunately, it appears to be out of stock and obsolete, looking at Farnell (Sweden) website.
ECOS1VA682BA - PANASONIC ELECTRONIC COMPONENTS - Elektrolytkondensator, TS-HA serie, 6800 µF, ± 20%, 35 V, 22 mm, 0.061 ohm | Farnell element14 Sverige.
You could fit the 50V version if necessary, try another supplier or brand. PANASONIC ELECTRONIC COMPONENTS - ECOS1HA682CA - Electrolytic Capacitor, TS-HA Series, 6800 µF, ± 20%, 50 V, 25 mm, 0.046 ohm | CPC UK