nad 3020 clicking sound when playing

[islanddancer]

Hello, Diyaudioers:
I recently bought a nad 3020 on ebay for $120.

But there is some clicking or cracking sound from it when playing,
I doubt it is from the input selector buttons.
There are 4 input selector buttons: aux, tuner, phono, tape.

and there is a loudness button and a audio muter button.

The clicking sound is different from that produced when I push and release the buttons,
very crisp and short, and it is especially obvious when I turn the volumn low to loud.

Normally the clicking sound does not affect the music, but occasionally it will cut the amp off with no power output.

Can you give me some troubleshooting guidelines on it?

Thanks!

[analog_sa]

Originally posted by islanddancer

Can you give me some troubleshooting guidelines on it?

Not really. Your description is not particularly specific.

You can make sure that it is indeed the preamp section to blame by removing the jumpers at the back and plugging a source with a built in volume control in the power amp section. Once the power amp has been cleared you can try to see if all preamp inputs behave the same way and this will eliminate the source selector. Are both channels equally affected?

It is really amazing how well the value of an entry level amp has kept up with inflation. I remember paying less than $90 for a brand new one around 1981.

[IsakAlexander]

So its not the old volume control pot that needs a good clean? Had the same amp and the volume pot needed replacing to function well on low to medium volume.

[islanddancer]

Originally posted by analog_sa



Not really. Your description is not particularly specific.

You can make sure that it is indeed the preamp section to blame by removing the jumpers at the back and plugging a source with a built in volume control in the power amp section. Once the power amp has been cleared you can try to see if all preamp inputs behave the same way and this will eliminate the source selector. Are both channels equally affected?

It is really amazing how well the value of an entry level amp has kept up with inflation. I remember paying less than $90 for a brand new one around 1981.

Thanks, I will check that.

The headphone output works perfectly and there is no clicking sound when I plug in my hd650.

with the clicking sound, the right channel of the speaker will intermittently shut off.

[islanddancer]

Originally posted by IsakAlexander
So its not the old volume control pot that needs a good clean? Had the same amp and the volume pot needed replacing to function well on low to medium volume.

Thanks.

In fact, the volumn knob is smooth. and I can't think of clicking sound comming from the knob...

[islanddancer]

Originally posted by analog_sa

It is really amazing how well the value of an entry level amp has kept up with inflation. I remember paying less than $90 for a brand new one around 1981.

I think I overpaid for that and it does not work well after I bought that 3 days ago. I was overwhelmed by reviews on line and did not know the original price.

Thanks.

[analog_sa]

Originally posted by islanddancer


The headphone output works perfectly and there is no clicking sound when I plug in my hd650.

with the clicking sound, the right channel of the speaker will intermittently shut off.

This may actually explain all. The headphone connects to the same output as the speakers but through resistors. There is a thermal fuse at output which disconnects the speaker connection under excess current conditions. It may also click. Very possibly it requires a replacement. It's easy to test by short-circuiting it underneath the board. Before doing that it may be advisable to check output offset and bias current.

[islanddancer]

Originally posted by analog_sa



This may actually explain all. The headphone connects to the same output as the speakers but through resistors. There is a thermal fuse at output which disconnects the speaker connection under excess current conditions. It may also click. Very possibly it requires a replacement. It's easy to test by short-circuiting it underneath the board. Before doing that it may be advisable to check output offset and bias current.

Thank you Sir.

I searched the web and got a schematic for it. I am not sure which is the fuse you are refering so I circled the one I suspect is the fuse. Could you please tell me if it is correct?

I have also got a picture of the 3020, could you please tell me which one is the fuse I need to replace.

[islanddancer]

Originally posted by islanddancer


Thank you Sir.

I searched the web and got a schematic for it. I am not sure which is the fuse you are refering so I circled the one I suspect is the fuse. Could you please tell me if it is correct?

I have also got a picture of the 3020, could you please tell me which one is the fuse I need to replace.

the left is my 3020.
Thank you Sir.

[analog_sa]

It is marked as TB1/TB2 on your circuit and it's right between the zoebel and the output inductor. It's a bimetal automatic fuse and i have no idea if it's easy to find a replacement, nor do i know at what current it trips. 10A? My guess is that yours is tripping early. Or you really listen loud.

Not enough resolution to spot them on your board picture but they should be close to their corresponding inductors. Square cross section, about an inch tall, black, two pins at the bottom iirc.

Again: before replacing or shorting check bias and offset just to be on the safe side.