Replacing Blown Fuses
If a fuse in one of your components — an amplifier, for example — needs to be replaced, use the exact type and rating specified by the manufacturer. That means paying attention not only to the amperage, but also the voltage rating, physical size and whether the fuse is fast-acting or time-delay.
A time-delay, sometimes called “slo-blow,” fuse is designed to tolerate brief increases in current such as the inrush that may occur when certain equipment is first switched on. A fast-acting fuse responds more quickly to an overcurrent condition. Neither is automatically better than the other. Use whichever type the equipment was designed to use. Time-delay fuses are specifically intended to tolerate short-duration surges while still providing sustained overload protection. IAEI Magazine
Never install a higher-amperage fuse simply because the correct one keeps blowing. The fuse is there to protect the equipment and, potentially, you. Increasing its rating can allow excessive current to flow before the fuse opens, which may cause substantially more damage or create a fire hazard.
You will also encounter both glass and ceramic cartridge fuses. Glass fuses are still commonly used, while ceramic construction is often chosen where greater heat resistance or higher interrupting capacity is needed. Some ceramic fuses also use fillers that help extinguish the electrical arc when the fuse opens. Littelfuse
Because you generally cannot visually inspect the element inside an opaque ceramic fuse, it may need to be removed and checked for continuity with a multimeter. Always unplug the equipment before removing or testing a fuse.
And don't automatically replace a glass fuse with a ceramic one simply because ceramic seems “safer.” The correct approach is to install the manufacturer-specified replacement or an electrically equivalent fuse with the proper ratings and characteristics.
One final point: if a replacement fuse blows again, stop. A fuse usually fails for a reason, and repeatedly replacing it may only allow an underlying problem to become worse.
If you're unsure what fuse your component requires, keep it simple and call or email us. We'd much rather help you identify the proper replacement than see an inexpensive fuse turn into an expensive repair.
—Lou