My experience would be stop playing with fuses until you get direction from the manufacturer.
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Cheap fuses don't always blow when they should. HiFi Tuning and other similar types blow when they should. Slow blow fuses are supposed to allow momentary rises of current above rated value provided they are very short in duration. If your slow blow fuse that came with your unit operates fine, then stick with only slow blow fuses. If you want to use a HiFi Tuning fuse, use one with the same rating, not a fast blow type.
Like Raquel says, talk to someone at HiFi or a dealer rep. Also, be prepared to give them the info, if you can, from the circuit board (the printed info next to the fuse holder) as it can help narrow down just what the designer intended. When I replaced two fuses on an amp I had, the info on the circuit board did NOT correspond to what one of the fuses were. The rep told me this happens more than you think and he sent out the correct fuses and I've never had a problem.
On another note, I stumbled upon an article on aircraft fuses and the author tested them and discovered that when a lesser make fuse reached 80% of thermal limit, repeatedly, it developed a memory and blew at the lower setting. I wonder if this might be happening in audio products as well as there are lots of stories out there about continually blowing fuses that no one can figure out.
Good luck in your search.
All the best,
Was that the article on circuit breakers?
For the straight skinny on fuse specs, the littlefuse site has a lot of information with little digging.
Yeah, memory MAY be an issue, but certainly not on a new fuse of the correct value and rating. Some may be putting 32v fuses where 250v is required? Instablow in that situation requires some investigation.
Yes, it was. I assumed (maybe incorrectly) that the same principle would apply to both circuit breakers and fuses where quality is an issue. In the article, the author goes on to refer to them as fuses so I assumed (again) that they operate on the same principle. One is replaced, the other reset.
Memory MAY be THE issue as a cheaper fuse conceivably couldn't withstand the repeated thermal stress as it nears its rating. I'm just throwing this out there.
There has been enough discussion, here, to support the use of better made fuses over cheaper ones. What the OP may be experiencing is his unit running close to its thermal limits too often. Or a fuse rating too low. A call to the maker would be in order to see if others are experiencing the same problem.
All the best,
I'd be curious to know what the UL test / qualification procedure are for fuses....
OR any other governing body, for that matter.
In a not-quite related phenom. Aluminum has no fatigue limit, so every mechanical stress cycle eats into ultimate lifetime.
Steel and its alloys have a fatigue limit which if not exceeded promises an essentially limitless liftime. Exceeding the fatigue limit begins stressing the structure and once you go over the tensile limit, you're all in.
Perhaps something similar with fuses, only electrical where the heat of passing current effect ultimate lifespan.
Seems a simple enough task for a manufacturer.
A quick test would no doubt ascertain current performance but do they test for the heat generated over a life cycle or is it mathematically arrived at?
It boggles my mind that a fast blow fuse goes in about 1/10th of a second and some slow blow fuses can go on for as long as tens of seconds. They're sacrificial in nature, so how does one guarantee consistency and do they dig deep enough into the specs when selecting them? Or for that matter, are the specs for heat generated wear taken for granted or even considered?
one MAJOR key is process control during manufacture
Measurement instruments....like for metal thickness, are checked on a regular basis, calibrated regularly and have a gauge R+R study done annually.
ISO standards require the above, so buying from an ISO certified builder is IMO, a Key Requirement.
Once you have a database, turn the math guys loose on it, you can build successful models of most anything. We used modeling extensively in semiconductor manufacture.
I expect fuses to have very regular materials....the right alloy, internal process control and a well-trained workforce working to the build specification.
Go to the littlefuse site and read around for further info. I saw a white-paper there about fuse ratings /
As for a test: It of course makes a huge difference. The test cycle could be anything from stuff like.....10 seconds on @80% fuse rating / 10 seconds off for 1 hour, followed by 'test to destruction'.
The other test cycles I'll leave up to your imagination. I just made that one up.
i have all my fuses replaced for high end ditos (Wadia 381, Barefoot MM27, Rives Audio PARC). Indeed i think it is first now i really benefit from it along with another rather cheap upgrade (Essential audiotools - Noise Eater). All of the fuses are slow blow. Ofcourse you should find the correct fuse(s) for you application, and try to change all of them.
I notice a significant increase in clarity/ transparency. The readability and dynamical contrast are more precisely rendered. I perceive a more lifelike rendition of voices and instruments than before.
I think this is perhaps the cheapest mod we can do.
Don't know if it matters (for you that is!), but this also makes me notice different things with different power chords.