All 3 amps blew there fuses. what now?

[skylerk99]

I have 3 Shure HTS 50SPA Amps and one day all three of the amps blew there fuses.
I was going to just buy the fuses and put them in but then i started reading that if an amp blows a fuse more damage can be done by simply replacing the fuses. SO i was just wondering what could cause all three to go out at once? Could it have been a surge? And what should i do now?

[djk]

The damage occurs when people use the wrong type fuse.

If you use an ordinary AGC type glass fuse to replace an ABC type ceramic fuse at say a 10A rating, the fuse will arc internally and pass way too much current before it opens.

I saw this frequently with the Peavey CS800. If they came in with the original fuse blown they were simple to fix, usually just outputs. If they came in with a glass fuse they would have blown outputs, emitter resistors, triac in crowbar, etc.

If you lost three at once I would have expected some sort of event or cause behind it all. I would check the neutral, and make sure you are not on the wild leg (three-phase open Delta).

Shure says if it blows the fuse a second time, do not replace again. Why they use a 10A slow-blow fuse for a 100W amp is beyond me, it offers no protection.