Should a fuse with the correct amps, but is physically too small, still power my stereo unit?

Question

I'm not sure if I'm asking the right kind of question for this site. But if someone could help me, I'd be grateful:

I blew a 125V 2.5A fuse in my home stereo head unit. I couldn't find that fuse at any stores nearby, but I was told 250V 2.5A would work just fine. I bought those but when I went to install it, I noticed I bought 3/4" size but need 1" size.

Even though it's too small to fit in the fuse clamp, I figured it would still work if I drop it in there and have the metal touching on both sides. My stereo powers up like it's working again, but now I get no sound; just humming from my speakers. I've checked all the speaker wires, they look fine.

Is this because the fuse is too small, or does it sound like i have another problem?

Answer 1

It sounds like you have another problem. Probably the problem that caused the original fuse to blow. Although electrically, the 3/4 inch fuse is fine (the 250 volt rating is higher than the original which is OK) since the current rating is the same as the original, the fact that it is loose in the holder is not OK. This can cause arcing as contact is made and unmade which could lead to a fire. It also can cause problems with the amplifier as the AC power is continually going on and off. I recommend replacing the fuse with the proper size and then seeing what happens.

Answer 2

The fuse doesn't power the unit nor does it protect the unit in most cases. It is a safety device in the case of a fault that might cause overheating, sparks, fire, etc.

If the new fuse is actually electrically completing the circuit without blowing and your unit is fine otherwise, your unit should work.

A fuse, generally speaking, is either going to complete the circuit or open the circuit with no in-between.

While I'm typing this answer, I see that Barry has given you the same advice that I was about to type: put the correct physical and electrical size fuse in to be safe.

If you unit is still malfunctioning, take it in for service.

Unless you were doing something with the connections or there was a power fluctuation etc. to blow the fuse, there is most likely a failure in the unit that blew the fuse and perhaps caused further damage.