Today i was cleaning and redressing my system. After everything was ready i tried to switch on all devices but i have problems with 250DR’s power button being stack. I fixed it but after that 250 would not come to life. Then i opened the fuse-box and i discovered that the previously working fuse (spare is ok) was broken into pieces. Is there anyway to clear the broken fuse myself?
ok, managed to release all the pieces of the old fuse using carefully a tiny screwdriver. Replaced the fuse with spare and system is back!
Nice problem solving my friend! 
So now i want buy some spare fuses for my devices. I need fuses for 250DR,SUPERCAP DR and 555DR. I see that SUPERCAP fuse is different rated: 2.5A vs 15A for 555 and 250. Out of curiosity why is that? I don’t know much about electronics but all these three devices use similar big transformers.
It’s very important to use the correct type and rating of fuse. Best get them from a Naim dealer to be certain.
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100%. Agreed.
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Like the others said, very important to use the correct one. And there’s more to electronics than transformer size. But even that is not the same.
250:
555:
Supercap:
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It’s because the power delivered by the Supercap is tiny compared with the other two. Note that it’s not just a question of the size of the fuse in Amps, it has to be a slow blow type, indicated by the letter T. As others have said, best get from a Naim dealer.
If you are going to buy them yourself, try to get them made by the Littel fuse company, this being what Naim uses. It’s very important to use the current rating that Naim specifies. It’s written next to the fuse holder on the back of the unit.
Best
David
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Though important to note that Littelfuse has more than one type that is slowblow and the correct rating. The one Naim uses is the 213 Series - 5x20mm Time Lag Surge Withstand Glass Body Cartridge.
021302.5MXP for SC and XPS, 02133.15MXP for 555 (and 300, I don’t know about 250). Which is 3.15 A for 555, not 15 A as @charnik wrote. (All values for 200-240V, as printed on the unit)
In any case, best to get from a Naim dealer
Very late edit for posterity: Apparently Tom Tom says it’s the 218 series:
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Its 3.15 amps, not 15.
Full spec is T3.15AL/250
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100%, do try to get the Littel. many moons ago I got involved in testing various ISO rated fuses & we found it was all over the place with numbers of ‘will-fit’ on the market. Much the same as still exists with the UK 13A in plug fuses, don’t be fooled by anything, kite marks & BS numbers may be more “BS” that you care to know.
Getting back to the Naim equipment fuses …
The fuse ratings are an International Standard that originated in Germany (TUV) & its nomenclature is based on German language
e.g. T3.15AL/250
The numbers are the fuse ampere rating according to the standard and the 'A 'following the number indicates Amps
The first alpha letter(s) indicates the categorised fuse breaking speed
The letter after ‘A’ is the categorised fuse breaking capacity
The / followed by number is the maximum voltage
Fuse Element Speed
FF Very Fast Acting (Flink Flink)
F Fast Acting (Flink)
M Medium Acting (Mitteltrage)
T Slow Acting (Trage)
TT Very Slow Acting (Trage Trage)
Fuse Breaking Capacity
H High Breaking Capacity
L Low Breaking Capacity
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All useful info - is there any info about this in the FAQ section I wonder or would Naim recommend dealer fuse changes?
I have no idea where replacement fuses are assuming I have any - presumably in old boxes in the attic.
Each unit has two fuses in the fuse holder. One in use and a spare. (Don’t know whether this applies to muso etc though.)
Best
David
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Thanks David - I wondered about that - sensible way of doing things.
I know I’ve had replacement fuses with some kit in the past just couldn’t really think if there were any loose ones from Naim and where I might have stashed them!
Just to add to what others have posted here, bear in mind that the fuse requirement is different depending on whether a unit is 230V or 115V. NEVER fit anything other than the exact correct fuse. The correct fuse rating will always be printed on the rear of the equipment. If in doubt please source replacement fuses from your Naim dealer. If replacement fuses continue to blow then it may indicate an equipment fault, in which case contact your Naim dealer.
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This what’s in the FAQ, but it does not include the precise type.
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