Is it safe to use .5 amp fuses?

[james.fugate]

I have Svetlana 6550 tubes in my RM100. I don't know if that has anything to do with the question but are .5 amp (500ma) fuses safe to use? I bought some b/c they didnt have any 400ma at Radio Shack.

 

[james.fugate]

Seriously guys...i need help ASAP.

 

[paintkilz]

are you talking for the Fast Blo tube protection?

or the mains fuse or something else?

 

[james.fugate]

Sorry, Fast blo tube.

 

[Mailman1971]

I have them in may amp(same problem Radio shack didnt carry them)
I see on the newer randalls that you can use .400 fuses it says on the back of the amps. MY amp says .250 but they kept blowing. I was worried about the .500 but figured....well what the hell. Use the fast blow ones and dont bias too hot. I keep it about 37 for my bias level on the EL34's.
Been using them for about 4 months with no problems. But I took a chance and havent had any problems. I guess your own risk. :wink:

 

[Jaded Faith]

I have them in may amp(same problem Radio shack didnt carry them)
I see on the newer randalls that you can use .400 fuses it says on the back of the amps. MY amp says .250 but they kept blowing. I was worried about the .500 but figured....well what the hell. Use the fast blow ones and dont bias too hot. I keep it about 37 for my bias level on the EL34's.
Been using them for about 4 months with no problems. But I took a chance and havent had any problems. I guess your own risk. :wink:

Same here, exactly what he said.

 

[Bewitagos1]

without having a schematic in front of me, its difficult to know why Randall nearly doubled the rating on the fuses but stopped short at .400mA

If 400mA is the maximum threshold for the circuit, a 500mA (1/2 amp) fuse is a 25% increase above that threshold.

So...a failed component wouldn?t know whether you had a 500mA fuse or a crowbar in place once its thermal integrity is breached - aka smoke.

Its not the fuse's size but what caused it to blow that should be piquing everyone's concern.

Jimmie