I was recently given an amp from my friends dad. He used it back in the day to play guitar. It is a tube amp, company Earth Sound Research 117V 60Hz 270W Model G-1000. Well the fuse was blown. It is a 2.5 Amp 125V Slow Blow fuse. I scowered the internet and found very little of any use.
So I decided to check radioshack and the like. The guy at radioshack said this fuse would work, 2.5 Amp 250V Slow Blow. Basically I'm asking for a second opionion. I bought the fuse, even though he seemed slightly unsure, because it was cheap. Will this fuse work? Or might I blow the amp and/or fuse?
This is from "kenselectronics.com":
The "AMP-rating" of a fuse is critical--never use a 20A fuse to replace a 2A fuse. Occasionally a fuse may blow because of the "power surge" that occurs when a device is turned on.
When replacement fuses blow: there is something seriously wrong with the unit it needs to be repaired (whatever made the original fuse blow) it has nothing to do with the VOLTAGE label on the fuse!
Using a 250V fuse (with the proper Amp-rating) in a 12 Volt or 117 Volt application cannot damage the equipment.
Fuses are "current-specific" devices; the VOLTAGE "doesn't really matter" to a fuse. Nearly all electronic stuff in the USA and Canada (with the exception of high power devices such as electric stoves, water heaters, etc.) operate on 117VAC.
Therefore 125V and 250V fuses can be used interchangably to protect nearly everything electronic.
Electric power outside the USA is different; Japan uses 100VAC (use 125V fuses) but Europe, Australia, India, Africa etc use 240VAC! (use 250V fuses)
Why do fuses have a "voltage label"? The "voltage rating" has to do with the width of the opening when a fuse blows--a fuse labeled as 125V or 250V is designed to have a wider gap between the remaining conductors (when it blows) than a fuse labeled at 32V. The labeled voltage on a fuse is the maximum circuit voltage that should be protected by that fuse.
Automotive 32 Volt fuses are commonly used for 6V, 12V & 24V applications because they may be a little cheaper than 125V or 250V fuses.
UL safety regulations allow 250V fuses to be used in 6V to 250V applications; 125V fuses may be used in 6V to 125V applications.
Using a 250V fuse in a 1000V application does not meet UL safety approval; however even a 32V fuse with the proper "Amp rating" in a 1000V circuit is less dangerous than using no fuse at all!
So, assuming you are in the US or Canada, as long as you got the amp rating right (2.5A), it appears you can use your 250v fuse to replace the 125v fuse, but you should not use a 125v fuse in an application calling for a 250v fuse. :)
"Everybody got to elevate from the norm."
Yeah, it'll work fine.
The voltage rating means that it's adequate to block a 250V circuit safely when it blows.
"A cheerful heart is good medicine."
Agreed, the 2.5A 250V fuse won't be a problem. I'd be more concerned about *why* the fuse blew. You'll probably need to replace the tubes and the filter caps, as nearly every older used tube amp I've ever come across needs this. Whenever I look at a used amp for a possible purchase, I automatically add in enough $$$ to re-tube, re-cap, and bias the amp.
That amp can be a very good-sounding amp. Stay away from Chinese or Russian tubes though, as I seem to recall that amp had a rather high B+ supply voltage, and those tubes won't take it. The other thing you may want to do is replace the shielded cables they used, mainly the one from the input jack to the first preamp stage, the one going to the center-post of the volume control from the tone stack, and the one going to the input of the phase-inverter. The shielded cable they used was very low-quality and had very high capacitance to ground, which rolled off the high-end response of the amp a great deal. The amp really 'came alive' and had a much better and glassier "Fender-like' high-end after getting rid of those crappy cables. Use good-quality insulated hookup wire rated at least 400V, and/or teflon-coated, as most teflon-coated (but not all) hookup-wire has a relatively high voltage rating.
Just so you know, that's a 100-watt amp, and as I recall from the one I worked on, a very loud 100-watter too. Very nice 'gimme' indeed! :D
Cheers!
Strat
