Hi! I'm so glad I've just found this forum. So many interesting posts and a lots of love for my ol' faithful amplifier, the NAD 3020.
Yesterday, after nearly 30 years in the family, my NAD 3020 developed a humming noise. I'm not too much of an expert but I'd say it is a constant low frequency noise (sub bassy) and is about 50% of the volume of what's being played. I've disconnected everything apart from the power lead and two speakers and it still hums.
Here are some details:
1. I have added no new electrical devices or changed any electrics in my house recently. The set up has been the same for months.
2. When the input selector is anything apart from the phono button (i.e. Tape, Aux, Tuner) the hum is much less but still affected by the balance, bass and treble, but not affected by the volume knob.
3. When phono is selected the hum is much louder and is affected by the volume dial. You can hear it (quite loudly) when volume is at zero and turning the volume past 12 o'clock is unbearable.
4. When I remove the pre-amp jumpers at the back of the unit the hum is still audible but always sounds exactly as it did in point 2 above, even with the Phono input.
5. My 3020 has had static issues for a few years but I've found a good clean and some contact spray usually sorts this out. The main area I've had difficulty with is the area behind the power switch. Those two big disc-shaped capacitors are always giving me crackling problems and I can even see little red lights occassionaly flashing in the switch they're connected to.
Now after that huge info dump I just really have a few questions to ask you in the hope that I can maybe save a bit of time and money by drawing on the collective knowledge of the board members here.
Q1. Does this sound like a simple case of replacing the capacitors at the power switch? I think they power the pre-amp too.
Q2. Does this sound more like a bigger issue with the pre-amp circuit board?
Q3. Or does this really sound like a huge headache, and I should go buy a new amp?
Look forward to seeing what you suggest. Thanks in advance!
John..
Yesterday, after nearly 30 years in the family, my NAD 3020 developed a humming noise. I'm not too much of an expert but I'd say it is a constant low frequency noise (sub bassy) and is about 50% of the volume of what's being played. I've disconnected everything apart from the power lead and two speakers and it still hums.
Here are some details:
1. I have added no new electrical devices or changed any electrics in my house recently. The set up has been the same for months.
2. When the input selector is anything apart from the phono button (i.e. Tape, Aux, Tuner) the hum is much less but still affected by the balance, bass and treble, but not affected by the volume knob.
3. When phono is selected the hum is much louder and is affected by the volume dial. You can hear it (quite loudly) when volume is at zero and turning the volume past 12 o'clock is unbearable.
4. When I remove the pre-amp jumpers at the back of the unit the hum is still audible but always sounds exactly as it did in point 2 above, even with the Phono input.
5. My 3020 has had static issues for a few years but I've found a good clean and some contact spray usually sorts this out. The main area I've had difficulty with is the area behind the power switch. Those two big disc-shaped capacitors are always giving me crackling problems and I can even see little red lights occassionaly flashing in the switch they're connected to.
Now after that huge info dump I just really have a few questions to ask you in the hope that I can maybe save a bit of time and money by drawing on the collective knowledge of the board members here.
Q1. Does this sound like a simple case of replacing the capacitors at the power switch? I think they power the pre-amp too.
Q2. Does this sound more like a bigger issue with the pre-amp circuit board?
Q3. Or does this really sound like a huge headache, and I should go buy a new amp?
Look forward to seeing what you suggest. Thanks in advance!
John..
i have had many of these amps over the years, the problem you describe is the 4 big power supply caps, you need to replace these, also to solve the power switch crackling problem replace the switch (this is what is causing the crackling) while you do this replace the caps that are connected to the switch.
chris
chris
Thanks guys. I'll probably get a local Brighton repair guy to fix all those capacitors and switch for me as it may be beyond my own skills.
If I show him which capacitors need changing would it be a simple job for him to find the right ones as well as a suitable new switch, i.e. will he need a NAD switch or a generic one?
I have seen a few 3020 schematics online, and even some detailed upgrade write-ups so I'll probably print them out and take them along with me if they need them.
Anyway, thanks for the help. Can't wait for another 30 years of unique audio from my NAD
John..
If I show him which capacitors need changing would it be a simple job for him to find the right ones as well as a suitable new switch, i.e. will he need a NAD switch or a generic one?
I have seen a few 3020 schematics online, and even some detailed upgrade write-ups so I'll probably print them out and take them along with me if they need them.
Anyway, thanks for the help. Can't wait for another 30 years of unique audio from my NAD
John..
NAD 3020 hum problem
I have the same issue with my NAD 3020 which I started using after many years of storage because I re-discovered how good it was with vinyl. After a few weeks of use it started humming/buzzing as described in this thread. The hum is not affected by the volume control.
I replaced the 4 big 2200mf power supply capacitors as I suspected them and because they had oozed orange goo! But I still have the problem.
I tried isolating the pre amp by removing the jumpers and connecting my CD player to the power amp. It still hummed so I guess not the caps there.
I'd really appreciate any advice as to what to look at next. I'm no expert but I realize it must be something in the power supply side.
Many thanks
I have the same issue with my NAD 3020 which I started using after many years of storage because I re-discovered how good it was with vinyl. After a few weeks of use it started humming/buzzing as described in this thread. The hum is not affected by the volume control.
I replaced the 4 big 2200mf power supply capacitors as I suspected them and because they had oozed orange goo! But I still have the problem.
I tried isolating the pre amp by removing the jumpers and connecting my CD player to the power amp. It still hummed so I guess not the caps there.
I'd really appreciate any advice as to what to look at next. I'm no expert but I realize it must be something in the power supply side.
Many thanks
I have a 3020. I believe any 3020 is worth fixing. You may find some worthwhile info @ tnt-audio.com
VERY low (60hz) hum? My $'s on rectifier(s). Mines on loan to a non techie or I'd ask him to check the PS voltage for ya.
You could check the PS voltage between the caps & ground. Then, if it looks easy, disconnect the caps & check it again. If the caps are good the 2nd reading should be about 30% lower. If you see a smaller difference....
You'll hear leaky caps as distortion; all failed as 120hz hum plus distortion. .
Cheers tony
VERY low (60hz) hum? My $'s on rectifier(s). Mines on loan to a non techie or I'd ask him to check the PS voltage for ya.
You could check the PS voltage between the caps & ground. Then, if it looks easy, disconnect the caps & check it again. If the caps are good the 2nd reading should be about 30% lower. If you see a smaller difference....
You'll hear leaky caps as distortion; all failed as 120hz hum plus distortion. .
Cheers tony
hello.
this is an old amp,so handle it with care and patience.
have you read all posts in this thread carefully?
does the amp work,can you hear music?
at first i would clean all contacts (power switch,input selector,pots,fuseholder,....) with a contact cleaner(spray).
after this you can begin to change parts (the electrolytics........)
greetings
this is an old amp,so handle it with care and patience.
have you read all posts in this thread carefully?
does the amp work,can you hear music?
at first i would clean all contacts (power switch,input selector,pots,fuseholder,....) with a contact cleaner(spray).
after this you can begin to change parts (the electrolytics........)
greetings
The phono section has a habit of amplifying any lo freq sounds. (what it supposed to do)
so thats why hum is louder on phono selector. however it could be the phono section on its own generating the noise, and bleeding thro to the power amp section.
short the phono inputs and see if there's a difference.
there's good reason to replace the caps suggested anyway first.
I had something like this, where a piece of jewelry bridged the input to case metalwork
so thats why hum is louder on phono selector. however it could be the phono section on its own generating the noise, and bleeding thro to the power amp section.
short the phono inputs and see if there's a difference.
there's good reason to replace the caps suggested anyway first.
I had something like this, where a piece of jewelry bridged the input to case metalwork
Mine started out that way. It was a failure of the power supply rail switching. Parts not available. These things are getting very old. ( and a long history of failures) As nice as they were, might troll e-bay for something built this century. Caps get old. Silicon generates micro flaws due to substrate impurities and fails, pots get noisy, connectors oxidize. If you get ten years out of anything electronic, consider it free after that and don't be upset when it needs replacing.
Deal, You may have more than one problem.
Deal, You may have more than one problem.
My 3020 started to have some hum as well. It wasn't the bulk caps however, rather one of the two auxiliary supply caps. I replaced both of them and it fixed the problem. I purchased replacements for the bulk caps just in case they start to go, but I saw no point to changing them out right now, as the ripple voltage on both pairs was quite reasonably low.
I must say that amp has been an incredible deal. It was recommended to me by Keith Johnson many years ago, who gave it his ultimate KOJ endorsement: "I didn't have to do anything to it to make it sound right." The switches wear out and the pot gets worn and dirty. As I use the power amp section now alone (the wonderful ideal of providing a direct PA input serves well) I just don't worry about switching, and my source (a Roland RD-500 keyboard) provides the level control. I use the amp to drive AKG K1000 headphones.
Oh---also: the orange goo is probably not ooze. Rather it is adhesive, to prevent the parts from breaking loose from the board.
Brad Wood
Do you know the capacitor numbers because i have no idea how to ID the auxiliary supply caps in my Nad 7020
One of mine required a whole new power regulation and switching section as well as the usual cap refresh. It also had a blown output section.
Some of the transistors were unobtainium but a half hour of internet cross referencing yielded perfectly fine modern equivalents.
All up cost me under $30 in parts and she sings again!
What parts did you have trouble sourcing?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.