amp blowing fuse

Yes, bad tubes could cause this. Pull the speaker cables off before you do any more experiments.

Swap out the tubes and you'll know. :)

Best,
E

which fuse what is?  Was it the AC line fuse in the IEC connector?  If so, a bad tube shouldn't blow that. That's more likely a switching surge issue.  Now if one of the tube fuses blew then yes, sounds like a bad tube.

There’s only one fuse externally on the amp. Pretty sure it’s for the tubes. There’s a jewel power indicator lamp that glows for about one second before the fuse blows.  I’m not hearing any noise through the speakers when this happens. You’re saying I should disconnect the speaker wires while experimenting?  I thought that was bad  don’t the amps want to see a load?  There’s also a 6sny7 tube. Could that also cause this?  

Try powering up without the power tubes, if it stays on, then tubes, if not, something else.

With a tube amp you should always keep the speakers hooked up. You are correct, tube amps need a load or else they can be damaged!

Just an update,  Problem was a bad rectifier tube  swapped it out and all seems well. now breaking in my new Tung soul 7581 tubes