NAD C320BEE no sound.

[Tommy72]

Hi! New member here. Happy to be here. Was hoping someone could help me out a little


I bought a cheap NAD C320BEE and i got scammed of course. When i powered it up it would not come out of protection mode. I googled some, and found out that the C421 cap is likely the culprit. I changed that one, and it worked.


BUT...theres no output sound! If i crank the volume to the max, i can hear it very faint in one speaker (only the tweeter), nothing in the other. On headphones i can hear it, but very low with max volume.


I saw that the 2 15000uF caps on the power supply board was blown (probably). One is bulging quite a bit, the other a little. A couple of others looks suspicious too.


Before i go and order anything...would this be the possible reason for not getting any output sound? OR is the problem likely to be something else? My skills are limited to simple component changes, so i dont want to waste money if its just going in the bin anyway.


Any help would be much appreciated!


Best Regards


Tommy

 

[nfsgame]

The bridges between Preout and Main-In are in place?

 

[Tommy72]

Lol, im such a noob. Now its working . Feel free to point fingers and laugh haha. Thanks nfsgame!

So...about the caps. Should i change those two bulging 15000uF? Wil lit make any difference at all? Or should i go all in and change them all? Ive heard that those JH caps are bad...is it worth it?

Regards

Tommy

 

[bullittstang]

IMO - if they are truly bulging, they should be replaced. If they "blow" it will cause a much larger and more difficult clean-up.
Regarding a whole unit re-cap, that is up to you and your experience. Price-wise you could replace most of the "important" caps for $30 or less for Nichicon or Elna.
I just did a 100% re-cap of a NAD 216THX and all the parts were $42 from Digi-key, I thought it was well worth it - granted it only an amplifier, so you will have 2-3 times as many caps to replace, but most will be small voltage and cheaper.

 

[Tommy72]

Ok bullitt. Ill do. Those to is the snap in type, no?

 

[sgrossklass]

Vents for these big caps tend to be on the bottom side, not the top. There's a plastic sheet up top that may bulge up a bit, but if you can easily push it in, there's no reason to worry. These rarely fail unless subjected to overvoltage, and since they tend to be a bit costly, I'd rather double-check. That said, NAD's parts quality tends to be rather low, so I wouldn't be surprised to find the odd small electrolytic that's suspicious looking.

 

[bullittstang]

I agree with @sgrossklass that you don't need to spend the money if they aren't bulging.
Can you post some quality photos so we can see what you are looking at. Will make responses much more relevant.

 

[Bill_P]

JH capacitors (Jianghai) used in NAD amplifiers are notoriously poor quality, especially the large filter caps in the power supply. In my NAD C372 a pair of JH 10000uF 80V caps short circuited which blew the mains fuse in the amp. The capacitors were not bulged but did measure near zero Ohms when I took them out for replacement. To be proactive I would just replace the large JH capacitors given their reputation and my own experience.

 

[Tommy72]

So here is the pic of the 15000uf caps. Not easy to give a clear impression, but as you can see one is bulging quite a lot, with a clear pointy top, the other just slightly rounded. And the one with the pointy top has come loose from the board, and been pushed up slightly it seems...as theres a small gap between it and the board.:


Imgur: The magic of the Internet


Another thing is some of the other caps...they have changed colour from JH's clear blue...to a more light colour. Idk if they are supposed to have different colours though...


Imgur: The magic of the Internet

 

[Tommy72]

And they are rock hard, cannot be pushed down at all.

 

[Tommy72]

If im multi posting im sorry. I cant edit. I want to add that the one with the most bulge is loose on the bord, and theres some brown gunk on the board too. The other one is still glued firmly in place

 

[Tommy72]

And another thing...someone has soldered in a cap and a resistor on the back of the board. I cant imagine this is doen by the factory...so i cant help wondering why they did this. Anyone care to guess? Its near the volume knob.


Imgur: The magic of the Internet

 

[Sqeek]

Hello Tommy72 the last photo you posted with the 2 caps on the back of the board one is a electrolytic and the other (is not a resistor) it is a ceramic capacitor and they both look stock check your schematics

If you dont have the schematics you can download the service manual here if you sign up for free NAD C320BEE - Manual - Stereo Integrated Amplifier - HiFi Engine

On the big electrolytic you posted a picture of on your #9 post comment look normal imo but one cant tell if there in specs without testing them with a ESR meter and a capacitor meter.

The brown gunk as you call it is most likely glue to hold them in place during the assembly of the amp

I have included a picture of my NAD 216 main cap's that look similar to the ones in your first picture on your #9 post comment and mine have been tested and are good

As far as the other picture on the #9 post comment the different color caps are maybe a different series from the same manufacture and are most likely ok.

 

[Tommy72]

Ok, thanks a lot Sqeek. I see now its a JH cap so your right. Im gonna leave it alone, as it is working fine as it is.

Thanks for your help guys!!