NAC 552 blown fuse

[salvo]

Hi all,

tonight while connecting a source to my NAC it just went off. The fuse was blown to pieces, so I cleaned it and used the second one still ok (presumably a spare one) The NAC now goes on for a second then powers off again. The second fuse though is ok. I am not clear what is happening : does the power supply need both fuses to power on? is it something else ? I am worried!

Please help
Salvo

[Richard.Dane]

Is the power switch latching properly?

[NigelB]

…and is the power cable (PowerLine?) properly seated?

[salvo]

Hi Richard, yes as usual, I think

[Richard.Dane]

So, the on/off switch is latching on OK but still powering off?

I would check that the Powerline is properly seated as per Nigel’s post above.

How to ensure your Powerline is properly connected

You need to push until the first major resistance - some stop there thinking it’s in, but it’s not, at least not properly. It then needs a much firmer push to open up the very tight jaws to make a proper grip on the pins. As you do so you’ll see the back part of the plug push backwards. Just be sure you are holding on to the front of the kit because otherwise the force needed will send it flying off the shelf. Also make sure you only handle the outer case of the IEC (i.e. don’t push from the b…

[salvo]

Hi Richard,

that is exactly what I had to do. The NAC in now back online. Thank you so much for your input; you never fail with your support

Overall, I still need to understand why the fuse has blown.

Best Regards all,
Salvo

[Richard.Dane]

If the Powerline isn’t fully in then it can arc and that can trigger the internal fuse to blow.

[IanRobertM]

@salvo

I still need to understand why the fuse has blown.

Fuses do age and can just blow. Do you know how old the original fuse was…?

I have a small stock of the correct (*) fuses for my 250 and my XPS. Those are the only fuses I have known to blow, though. I have never had any other fuse blow, such as a HiCap… (thats tempting fate… lols)

[* They do need to be the correct type & rating - check with your Naim dealer.]

[salvo]

What I am afraid of is to push really hard the Powerline into the socket. It has always seems to me that somehow it does not bind very well. Maybe I should try on another less worthy socket to see it the Powerline “cliks” in into place.

[salvo]

IanRobertM, you’re probably right. Never had such problem since purchasing the NAC 9 years ago.

Thanks

[IanRobertM]

Do you leave it powered on…? Or do you switch it off, if not in use…?

[HouseholdNaim]

I’ve never felt the supposed click into place, but am happy that it’s fully located. As long as one hand is on the front panel pushing equally in the opposite direction you can push as hard as you need to to seat the plug round the back. As long as you’re pushing on the outer conical part of it it’ll go in properly and leave the tell-tale gap at the back of the moulding.

[salvo]

IanRobertM : My system is always on (although feeling a bit guilty for using electricity this way)

[Richard.Dane]

Yes, there’s no “click” as such, but you should be able to feel the first resistance eventually give way to allow the (very tight) jaws to open up properly onto the pins. In developing the Powerline, Naim found that the tighter the jaws gripped the pins the better the performance. That’s why they are as tight as regulations allow.

[HappyListener]

Richard,

Having blown a fuse on my 500PS ~ a year ago (first time after ~25 years of Naim ownership and unnerving like for @salvo ), I think the weight of the PL cable also plays here, especially if the PS is high-up in a Fraim stack.

Another joy of Naim ownership is having to plan where to put sockets/power feeds for the kit

I find IECs fine on flat surfaces (e.g. for kettles etc) and have always wondered if the more robust and tighter male end of the PL is where the primary benefit stems from(?) given the leverage cum torque which the cabling places on the connections when feeding a stacked item. My legacy Naim IECs were always a tad loose and prone to sag !

[Richard.Dane]

The Powerline’s jaws grips so firmly that if it’s properly inserted the weight of the cable should have no bearing. Indeed, it grips hard enough that it’s possible to lift something like a Hicap off the ground with the PL (I don’t advise this by the way!). Note though that the moulded end of Naim’s power cables is designed not to mate tightly with the IEC socket to aid decoupling.