I have an older 2-channel Sanyo audio receiver. It takes two fuses (one fuse for each speaker channel). The fuses that were originally in the receiver were 2A fuses. They are blown and I need to find replacements. I have two 4A fuses I pulled from an old stereo component system. They're both the same as the original fuses but they're 4A. Would it be safe for me to put them in the receiver? And if so, could I be able to turn the system up fairly loud without frying it due to using 4A fuses? Or should I avoid this altogether? It doesn't matter if I fry the system because it's old, but I'm more concerned if it created sparks or smoke or even started a fire.
You would be safe yourself, but not your audio receiver as the fuse is there for a reason.
The older gentleman is correct. You can use 4A fuses, but if one of your speakers (or wires) shorts out, that action might destroy the amp instead of blowing that fuse. No, you will not get more power out of it, but make sure that the unit has enough ventilation to properly breath so it doesn't get too hot during operation.
It's probably safe. There's a margin of error. Higher rated fuses are not going to by themselves create a dangerous situation, especially in the speaker leads. It's not going to let you play louder music though - that's limited by the design of the amplifier. The type of situation that would be dangerous is like if you had a reading lamp with a 2A fuse and 3A rated wire. So you swap the 2A fuse for a 13A fuse, and plug a 10A electric kettle into the light socket. Now you are pulling 10A down the 3A wire, and it gets hot and sets fire to the pile of old newspapers you had left on top of the wire.
If the reciever powers-up without these fuses, they are there to protect the speakers more so than the reciever. As the other fellow mentioned, however they do protect the reciever amp outputs in case of a speaker wire short. Once the speakers are connected this is fairly rare though it can happen while connecting the speakers - prudence dictates connecting the speakers with the amp off. If you use a fuse with a higher rating, and either turn the amp up too loud or (depending on the amp design) an output device fails, you will be more likely to blow up the speakers than the amp. If you don't mind this risk and don't intend to play the system very loud, it is probably safe; just be aware that your speakers are at some risk
