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Fuse Blowing on Superamp AE 25

Hello!
My AE 25 suddenly blew the main AC (2 amp sloblo) fuse. I took off the bottom cover and can find nothing that looks like a problem - no swollen components, no melting anywhere, etc.
Has anyone else experienced this? I am waiting for mail-order fuses now, and will put in a new one and try it, but it will be two weeks before they arrive. Meanwhile, I'm wondering if this is a common problem - maybe an AC spike that did it if the normal operating current is close to 2 amps? Any experience with this out there?
aatos
yogiboy's avatar
yogiboy
5,679 posts
 
It could have been a power surge. Why are you mail ordering a simple 2 amp fuse? Don't you have a radio shack or hardware store near?
newbee
4,767 posts
 
You may have had a power tube short out.
aatos OP
6 posts
 
Thanks for the idea. I will pull out all tubes before I put in the new fuse, then insert one at a time. Would that cause a problem?

No radioshack around here. No one I have shown the fuse to has ever seen one. Not an audiophile town.
newbee
4,767 posts
 
2 caveats w/new tubes, 1)be sure to turn bias screws back (counter clockwise) to minimum before you insert new tubes and turn on. 2) Although it was not a problem for me with my Cary amps, it is not unusual for a power tube loss to be accommodated by a blown out resistor in the bias curcuit. You should note this when you bias new tubes if it exists.

Hope that solves your problem.
aatos OP
6 posts
 
I will still be waiting for fuses for a while, but I have checked all tubes with an ohm meter, and checked to fuses on the current source tubes. Nothing unusual. of course, it may be that the low voltage of the ohm meter may show nothing that occurs at high voltage. Still, at only a few hundred volts, there wouldn't be any significant dielectric breakdown, I would think. Am I wrong?
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