What does a fuse do (in an amplifier)

[larry_emder]

Never quite figured it out......what function does it have in the signal chain? Does it influence tone in any way?
I recently bought new fuses for my lil' mesa after reading the beer can threadi n the vault.....but have no idea how i would go about replacing one if it did break....for that matter, i wouldnt know if it had broken in the first place!

Heres a pic of the back of my amp:

Theres a knob in the top left hand corner for the fuse....i have no idea how to access the fuse though.....do i pull on the knob, twist it....any advice?:smack: Better to ask first right???

 

[That90'sGuy]

Re: What does a fuse do (in an amplifier)

Fuses act in an amplifier the same they would any other electrical circuit, they protect it. In short, fuses stop overcurrent. If something were to get shorted (like coils on an output transformer), the rest of the circuit wouldn't burn up from the excessive amperage. The fuse is rated at a certain voltage and amp rating and if the overcurrent exceeds that, the link in the fuse will burn up destroying any links to the rest of the circuit.

Scott_F has mentioned this in the past (I think there's an article in the Vault on this), but you should always replace a blown fuse with a fuse of the same EXACT rating. The fuse has absolutely no bearing on the tone of the amplifier, so you get fuses at Radio Shack that will do what you want to do (just make sure you match the exact ratings)

To access the fuses, press in and then twist and it should pop out. If your amplifier ever stops working out of nowhere, make a habit of checking that first! If it's blown, I'd recommend taking it to a tech to get checked out (chances are there's a reason why it's blowing and it should be taken care of immediately).

 

[Bludave]

Re: What does a fuse do (in an amplifier)

Cris is dead on!!!! I cantell you from personal experience ALWAYS..... ALWAYS carry the correct replacement fuses for the amp you are using.


A very long time ago I was playing a GIG and blew the fuse in my '66 vibrolux. I did not have a spare.......... so needing to get the amp working I suffed the fuse holder with tin foil. 1 or 2 songs later I smelle something burning. It was the trannys in my amp. A very expensive learning experience for a inexperienced 16 year old kid. :smack: I fried the amp and had to replace it. I am not proud of this stupid act, but hopefully others can learn what not to do. It educated me to always carry fuses for the amp!

The story gets worse....... keep in mind this happend around 1968, so a '66 lux was just a "used" amp at the time. After this incident I put the amp in my Moms basement and forgot about it for a long time. About 15 years ago I went to get the amp and repair it. My Mom had thrown "that old thing" in the trash!!!!! So somewhere in the Bethpage NY town dump is my 1966 Vibrolux that needs a tranny. It still was all original:smack:

 

[larry_emder]

Re: What does a fuse do (in an amplifier)

OUCH!

Yeah i'm pretty sure i bought the correct rating fuses as a backup.

Thanks chris mate, i figured out how to access the tube now :dance: Good man

 

[SlyFoxx]

Re: What does a fuse do (in an amplifier)

I always duct tape a set of fuses to the amp itself. Can't lose 'em that way and they always stay handy.

 

[cream123]

Re: What does a fuse do (in an amplifier)

Cris is dead on!!!! I cantell you from personal experience ALWAYS..... ALWAYS carry the correct replacement fuses for the amp you are using.


A very long time ago I was playing a GIG and blew the fuse in my '66 vibrolux. I did not have a spare.......... so needing to get the amp working I suffed the fuse holder with tin foil. 1 or 2 songs later I smelle something burning. It was the trannys in my amp. A very expensive learning experience for a inexperienced 16 year old kid. :smack: I fried the amp and had to replace it. I am not proud of this stupid act, but hopefully others can learn what not to do. It educated me to always carry fuses for the amp!

The story gets worse....... keep in mind this happend around 1968, so a '66 lux was just a "used" amp at the time. After this incident I put the amp in my Moms basement and forgot about it for a long time. About 15 years ago I went to get the amp and repair it. My Mom had thrown "that old thing" in the trash!!!!! So somewhere in the Bethpage NY town dump is my 1966 Vibrolux that needs a tranny. It still was all original:smack:

oooo, that sucks

 

[LesStrat]

Re: What does a fuse do (in an amplifier)

As said, it's a circuit breaker.

Sly, my Dad used to do the same thing!

 

[Scott_F]

Re: What does a fuse do (in an amplifier)

I am guilty of using the aluminum foil trick on outdoor christmas lights. Usually I have too many of them strung together and the one closests the plug will blow. I check them though rather often. The fuses they put in there are too weak IMHO.

 

[That90'sGuy]

Re: What does a fuse do (in an amplifier)

OUCH!

Yeah i'm pretty sure i bought the correct rating fuses as a backup.

Thanks chris mate, i figured out how to access the tube now :dance: Good man

You're welcome A lot of people think they can replace a fuse with another one of a higher rating, so that's why I was stressing that it's a must to match what the amp manufacturer directly specifies for the circuit.

BluDave, ouch, I feel your pain on that :blackeye:

 

[The Golden Boy]

Re: What does a fuse do (in an amplifier)

I always duct tape a set of fuses to the amp itself. Can't lose 'em that way and they always stay handy.

I was having an issue with my bass amp constantly blowing output fuses- I had to carry a lot of fuses with me. After installing ventilation into the rack, my problem was solved, but I still keep the fuses taped in there.