Sorry for the inline comments. It wouldn't make any sense otherwise. Hope it does this way :)
> ________________________________
> From: Stefan Trethan <stefan_trethan@...>
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Tue, March 9, 2010 10:25:58 PM
> Subject: Re: [Homebrew_PCBs] PCB fuse
>
>
> You appear to be under the impression that fuses should be replaceable?
>
He's not alone. Not sure if anyone cares, but I also think it's a much better idea to have a fuse enclosed in an electrically and thermally (!) isolated container rather than a trace on the PCB itself. I'd find it hard to find any reason to choose the latter over the former. Any defect in the manufacturing process (or a minor difference in the choice of materials, like using another laminate with slightly different properties) could render a "PCB fuse" worthless. Not to mention that it could aggravate the issue by creating another possible source of fire hazard and damaging the PCB if higher currents are involved.
> Usually this is not the case, fuses are there to prevent fire and/or
> other danger if something goes wrong.
> Changing the fuse will not solve the problem, since it blew for a reason.
> You are supposed to throw the thing out once it is broken, not repair it. ;-)
>
I'm pretty confused now. Sure thing: fuses (in the majority of cases) blow because the POS behind them drew more current than it should have. But I certainly don't feel like wasting hundreds or thousands of $'s worth of fine electronics if an electrolytic capacitor decides to give up in a SMPS, even if I'm supposed to. In fact, I believe that no one should, at least as long as repairs are (financially) feasible.
Most people won't even attempt repairing a faulty component on their own and if they do, they're aware (or at least they should be) of the risks associated with the procedure.
A skilled technician or engineer on the other hand would find it _really_ annoying if they were expected to find a way to "replicate" a blown PCB fuse. In fact, the only thing they could responsibly tell the customer is to throw it away, because it's clearly not meant to be repaired.
> The only situation where a replaceable fuse makes some sense is if you
> have like an outlet or something to which the user can connect stuff.
> But more and more the trend goes towards not providing a user
> replaceable fuse because people can't be trusted to replace with the
> same rating, no matter how many warnings you print on.
>
I couldn't agree more. People with no experience working with electronics shouldn't be trusted with this. That's why they came to mount the fuse holder inside the case on the PCB (or somewhere else where it's inaccessible from the outside) - still replaceable, but only by those who make an explicit decision to disassemble it.
Gabor
> ST
>
On Tue, Mar 9, 2010 at 9:57 PM, David Griffith <dgriffi@.... edu> wrote:
> I'm curious why someone would want to use such a fuse in the first place.
> How do you replace it? Are there pads for adding a fuse holder after the
> PCB fuse blows?
>
> --
> David Griffith
> dgriffi@.... edu
>