Had a chance to take our noisy NAC 552 power supply to another property today. It all measured about the same noise wise at 25 DB room noise before powered on and 35 DB close to power supply when powered on. This was on the other house mains supply old looking switched plug, not dedicated, fridge plugged in boiler on etc. So unless the whole two town area has overly high voltage it’s a power supply issue.
Unfortunately when I got it installed back at home the NAP 500 wouldn’t power up, perhaps all this on off switching has blown an internal fuse, the Powerline is fine. Any suggestions?
Did you check the fuse?
By the way, you can easily measure the mains voltage with a digital multimeter from Amazon or whatever, for 25 euros or so. (It’s the other stuff like waveform distortion that is difficult)
Bear in mind I worked at a Naim dealer in the UK for over 6 years. Never heard the hum once in the shop and no customer ever once mentioned it.
I do think the forum (and this is a good thing) amplifies any problems because anyone who has them can compare notes. It’s natural that on a thread about hum, 99 or even 100% of anyone who posts has had the same problem.
It might be interesting to know how many people on the Forum have experienced Naim Transformer hums. Perhaps we need a Poll that says “Have you ever experienced Naim Transformer Hum? Yes/No”
Hi @Suedkiez , I swapped over the Powerline cables from one power supply to another and the plugs both worked. Is there a fuse in the 500 somewhere else? Everything is switched off now, no music
Hi @Guinnless, thanks for your help. I wasn’t aware of any other fuses, is the pop out on the 500 main body or it’s ps and do you know what type of fuse it uses, I’ll have to order one in pdq.
I don’t know which fuse value the 500 requires, but the fuse is most likely as follows:
Manufacturer: Littelfuse
Series: 213
Size: 5x20mm
Type: Antisurge (“T”), slow-blow
Rating: Not sure as I have no 500. It is printed on the fuse cover and stamped onto the fuse itself. Probably 3.15 Ampere like the 300PS and 555PS, which would be Littelfuse part number 02133.15MXP.
(Smaller units have 2.5 Ampere like the XPS and SuperCap, which would be the Littelfuse part number 021302.5MXP)
Your Naim dealer can supply (or there are shops like www mouser dot com). Get a bunch as backup
Very late edit for posterity: Apparently Tom Tom says it’s the 218 series:
One thing everyone should have in their toolbox, even if not technically minded is a mains tester with a voltage readout.
They differ from multimeters insofar as they are very basic and have (usually) no buttons at all. You just plug them in and they tell you the voltage and also have 3 lights which light in a certain order to tell you if
Earth is truly grounded.
Live and neutral are in phase.
Earth and neutral are on the right pins.
Ideally, any new property you move into should be preceded by a quick whiz round to sanity test all the sockets. It’s good practice regardless of hifi intent. It tells you nothing of the quality of the mains but rules out dumbass mistakes when the wiring was done - some of which can actually lead to hum in some countries (I think this depends on whether the mains in your country has live referenced to neutral or to ground).
