NAD C542 - almighty hum...

[Amyl Right Mate]

Hi,

I've recently bought a 2nd hand NAD C542 CDP.

When plugged into my amp and the input selected there is a loud humming sound. Even if the CDP is switched off on the front panel, as long as the CD input is selected, there is an almighty hum.

Is this a grounding issue of some kind? The plug attached to the mains cable is like a 2 pin shaver plug inserted in to a kind of 3 pin adaptor. Is that usual for NAD products?

Anyway, many thanks for any suggestions. Matt.

 

[floyd droid]

Where did you buy the cdp from ?. The plug you describe reads to me like a european jobbie. Im not entirely sure about (make that no idea ! ) how these plugs work regarding the earth pin,well lack of i should say. However i bought a meat mincer of all things off fleabay a while back,i was aware it had a 2 pin plug,so i cut it off and rewired onto our 3 pin,no problems. Maybe your hum prob is earth related as your post hints towards. Hopefully someone more electricaly minded will be along shortly. BUT if you decide to cut the plug off then thats up to you. Just to be 100% sure of this i suggest you hold fire a bit.

 

[Amyl Right Mate]

Thanks for that.

This is more or less sorted now. I believe was some sort of earth/ground problem.

In a moment of inspiration/frustration, I connected the NAD link in/out to the similar, but not compatible, Marantz IR in/out thing on my amp and low and behold - no hum. Not quite no hum but 95% reduced and pretty much unnoticable at my typical listening volumes.

I'm happy for now anyway and will probably investigate further at some point.

 

[chebby]

Amyl Right Mate:I connected the NAD link in/out to the similar, but not compatible, Marantz IR in/out thing on my amp...

Not clear to me what you mean.

"Marantz IR in/out". Is IR infra-red in this context?

"similar, but not compatible". I am still in the dark here.

Do you mean you connected the optical (Toslink) from the NAD CD player to an optical input on an AV receiver instead of using an RCA phono connection? (In which case the root cause of the mains hum problem is still there but not being passed on due to using an optical connection.)

Would there really be any problem in chopping off the two pin plug + adaptor and fitting a standard UK 3 pin mains plug?

Can we have a picture of this 2 pin plug and the adaptor?

 

[Amyl Right Mate]

Sorry for the confusion...

I have replaced the euro plug with a UK one. This didn't remove the hum.

The CDP has been connected all along to my stereo amp via the red/white analogue RCA's.

On the CD player there is an i/o called "NAD link" which is for passing remote control signals between components or somesuch. There are similar inputs on the amp, I believe that they are not intercompatible between brands. However, in this instance, it appears to ground the CD player getting rid of the hum. Don't ask me how. But problem solved (sort of.)

The solution I've (badly) described stopped the hum but also stopped my amp's remote working.

Now I have chopped the end off of a crummy RCA cable stripped the end and run it from the NAD link out to the turntable ground. Hum gone. What a palaver.

 

[floyd droid]

chebby:

Would there really be any problem in chopping off the two pin plug + adaptor and fitting a standard UK 3 pin mains plug?

Can we have a picture of this 2 pin plug and the adaptor?

As i said in my post chebby, ive done this before,no problems. I just wanted to cover my backside. Well we dont need another white van man saga,do we ???. Ah, and the eu 2 pin has different centres across the pins compared to our 2 pin razor plugs.

 

[Amyl Right Mate]

chebby:
Can we have a picture of this 2 pin plug and the adaptor?

For the record the plug set up was exactly like this: link

 

[Anonymous]

Excuse me if I'm saying something silly, but does earthing pin matter on the C542?? I have the C545 and the plug & cable on the CD player side is 2 pin?? I really don't understand why but there is just 2 pins on CD player side but cable is standard UK 3 pin with earthing pin beaing metal and not plastic...

 

[nads]

noble:Excuse me if I'm saying something silly, but does earthing pin matter on the C542?? I have the C545 and the plug & cable on the CD player side is 2 pin?? I really don't understand why but there is just 2 pins on CD player side but cable is standard UK 3 pin with earthing pin beaing metal and not plastic...

does not matter at all as there is only two wires. and the Unit is double insulated.

PROTECTIVELY EARTHED AND DOUBLE INSULATED EQUIPMENT
Protectively earthed equipment has the metal parts of the equipment connected, and bonded to the
earth wire of the supply cable. All protectively earthed equipment must use a 3-pin plug.
Double insulated equipment does not have any connection to the earth wire. Instead it has a double
layer of insulation or reinforced insulation and often has a 2-pin plug.
Double insulated equipment should be identified with the symbol of a small
square inside a larger square (usually located on the back near the serial
number) or be marked with the words 'DOUBLE INSULATED'.
While a double insulated appliance (such as an electric drill) has a plastic body
providing an additional layer of insulation there may still be exposed metal parts
(such as the drill chuck).

I think there is something wrong with the OPs unit or set up.

 

[Amyl Right Mate]

nads:
I think there is something wrong with the OPs unit or set up.

Clearly, but I've found a workaround soloution that'll do for the time being.