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Preamp repeatedly blows fuses

I've got an Antique Sound USA PA-5 preamp from 1997 that keeps blowing fuses. I originally found the problem last night when I walked away from my chair and came back to find the preamp dead.

I immediately pulled the fuse and it was an "F3A250V" quick blow. I replaced it this afternoon and as soon as I turned on the preamp, it blew the new fuse. No fireworks, no pops, just a dead preamp.

I don't know where to go next, other than to call my local tube amp repair shop.

Any thoughts?
128x128ekwisnek
ekwisnek's avatar
ekwisnek OP
27 posts
 
Th fuse I replaced was the line fuse. after a thorough inspection, I couldn't locate any other fuses on the unit. Keep in mind, this is an ASUSA product, not an Antique Sound Labs product. If memory serves, ASUSA was bought out by ASL. It's a pretty complex design...everything is through-hole and point to point with not much spare room inside the chassis. I did the old "sniff" test and smelled nothing "burny" inside. I also tried my best to find a bare wire shorted to the chassis, or a tube socket...but I just couldn't. I'm going to call Music Technology here in VA, they are about 15 minutes south of me and I'm sure they can help.

Keep the suggestions coming, though :)

Evan
hevac1
812 posts
 
Just asking, but did you disconnect all inputs and outputs? This way you will be sure that another item connected to your preamp is not causing the fuse to blow.
Maybe you have a shorted interconnect.
ekwisnek's avatar
ekwisnek OP
27 posts
 
I did disconnect everything, and isolated the preamp on a different outlet in the apartment.

Luckily I dropped it off at Music Technology this afternoon and Bill set me straight. Hopefully in a week or so I'll have it back and better than ever!
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