20 amp fuses?

[Rhodesplyr]

I've found 20 amp fuses in several amps I've worked on lately, the last one where it's supposed to be 2 amps.

Is the 20 amp fuse a standard value for the "who cares if it burns up" crowd? :-)

[g1]

Probably the most standard value auto fuse back when cars used that style fuse. "I think I saw one like that in the glovebox of Dad's old car" etc. Or if the local gas station/hardware store, whatever has only one value in that style, it's likely 20Amp.
Wonder what average value tin foil turns a fuse into?

[Enzo]

My reaction also. In many people's lives, the only place glass cylinder fuses show up is in the car. So they go get them and stick them in everything.


One time I took in an amp and in place of the fuse they had sawed off a length of 1/4" bolt and snapped it in there.

[Rhodesplyr]

Ah, that makes perfect sense! My 1964 Pontiac Star Chief used that style fuse. And unlike many modern cars, they were all in the same place.

[J M Fahey]

I always find either car/motorcycle ones, rolled up aluminum paper (cigarette or cooking type) or the "professional" type: a single "hair" pulled from a regular power wire.
The last one at least blows before your house/breaker does.
The mentality is "hell, it already broke, I *might* even repair it and finish the show"
They don't know that they turn a free (under warranty) repair into a new board swapping (because usually tracks blow and PCB carbonizes) costing 50% of the *new* amp price and close to the market value of the used specimen they have.
Oh well.

[Steve Conner]

After I've tested those fake transistors, I might do an investigation into how much current these fuse replacements can take. I don't think I have any power supply strong enough to really worry a 1/4" bolt, though.

[J M Fahey]

Well, the bolt and the crumpled aluminum *never* blow, that meaning no home line has so much current capability, anyway, the Utility Pole one will blow first.
The problem with car fuses is that the 20A are nominal, they just use a *strip* of lead; no copper wire there.
I guess that some of them *might* even take 30 or 40A, which still works in a car because the Battery can provide in the order of 300A, at least for a couple minutes.
The single copper "hair", which is around 0.1mm, may blow with 5 to 10 A, not *that* bad.
Test all them with car batteries, a digital/storage triggered scope and a piece of wire in series , chosen to have 0.01 ohm, which can provide a beautiful waveform of the current pulse.
Use a glass shield between you and the fuse, they will explode literally.
Unless you find metallized RayBan glasses too expensive and prefer to metallize your eyeballs directly.
Post it please.

[jrfrond]

Wonder what average value tin foil turns a fuse into?

That would be the 300A No-Blo fuse!

The Crown PSA-2 and Yamaha P2700, amongst others, use AGC20 fuses in the mains.

[Enzo]

We discovererd some Klipsch speakers with 20A fuses in them. Went on to find out they were STOCK!!!

The people at Klipsch explain - they don;t believe in speaker fuses. They don;t act fast enough to save drivers, unless you reduce their value to the point they blow on peaks. But some customers were demanding fuses, so they added fuse holders, but stuffed them with 20A fuses. So basically: Here! You got fuses, and they won;t interfere with the speakers. if you want smaller fuses, come up with a value on your own.

I like the Klipsch people.