Amplifiers

[Sarjahurmaaja.]

My old, old stereo amplifier has recently become very cranky. A few days ago it blasted the two fuses that are located inside the casing. I had them replaced with two fuses of the same type, or at least nearly (old ones: 4A/250V, t-type; new ones: 4A/250V f-type). Now, when I put the new ones in and tested them, they too were burned almost instantly (with a scary blue flash, even). Now, is this because they were f-type fuses, or does that have any effect?

 

Help would be very welcome.