Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kingplank on January 09, 2015, 02:58:55 pm

Title: 5E3 blown fuse
Post by: kingplank on January 09, 2015, 02:58:55 pm

Recently my 5E3 blown a B+ fuse after 2 years of continuous use.  (amp built with quality components)

After checking all the tubes and checking all the caps  I have found nothing out of the ordinary.
There are no burn marks, the power tubes resisters are good, OT have correct resistance values; I am stump what could be wrong and now I am hesitant to fire it up.

Anyone have any suggestions?
Thanks

Title: Re: 5E3 blown fuse
Post by: HotBluePlates on January 09, 2015, 07:18:22 pm

Put in a new fuse and try it out.

Title: Re: 5E3 blown fuse
Post by: PRR on January 12, 2015, 11:32:46 pm

Fuses sometimes die "for no reason". Often because they can just carry the steady load but are fatigued by thermal stress after many on/off cycles.

In the old days, we'd just wrap the dead fuse in foil, plug-in. If something was really wrong, it would become clear (or clouded), perhaps with collateral damage. Can learn a lot that way. But maybe you do not want a lesson on electronics and fires from your good amp.

Title: Re: 5E3 blown fuse
Post by: kingplank on January 23, 2015, 09:22:47 am

Thanks for the replies.

I think what PRR suggested was what actually happened. Slow blow fuse just melted everything around it.

Took the opportunity to rewire the amp, neater job due to more experience now. Checked all components. Gait it a first soft start, and everything is good