Fuse Question

[keninverse]

My brother bought this sunn beat lead amp and it's not working.  I'm trying to replace the fuses off the transformer but I can't figure out what type of fuse to use.  I found the schematic and it says to use a 10A 3AG fuse...but what about voltage?  Can you use a 250V fuse when the power supply runs ~40V?  Should I use fast/slow/normal blow fuses.  BTW it's a solid state amp...

[Paul Marossy]

From what I can tell about the 3AG 10A fuse, it's a fast acting type. It seems like everything I can find on it is rated for 250V, though...
I think the fuse cares more about the amps that it sees than the voltage.

[R.G.]

Fuses blow when the filament absorbs enough energy (current squared times time of current flow) to overheat the filament. Voltage has nothing to do with blowing.

Voltage has almost everything to do with interrupting the current though. Fuses are rated as to the maximum voltage they can interrupt. The "250V" rating indicates that the fuse is designed to reliabily quench the arc that forms when the voltage between the two ends of the melted filament is up to 250V.  If you tried to use this fuse on a 440Vac setup, the filament would melt, a stable arc would form, and the arc would start a fire.

You're OK with 3ag/250V on a solid state amp.

[keninverse]

thanks guys.
one more question...should I use slow blo fuses to allow for high in-rush currents?