Blowing Fuses in a Tube Amp

Can you adjust the bias? Mine was blowing fuses constantly, took it for repair, found the tubes were overbiased.

bias can be the main problem. what tubes your amp is using?
i can tell you what tube pin you should check for grid voltage in order to have a correct bias before you place the new tubes there. also i can direct or perform an installation of the bias measurement circuit almost on any tube amp with potentiometers for a neccessary adjustement when needed.

Does the amp have a tube rectifier ? If it does, it is a good place to look.

I have a CJ MV-50. It was blowing fuses, I think it was the Svetlana EL34's. I replaced them with old Mullards that BARELY tested good and have not had a problem. So I think maybe you should try different tubes. The Mullards also sound better.

You also could have an output tube with an internal short. If you have a tube tester, you can find out right away, or you can simply replace the tube.

Or, you may have the wrong fuse type. If your amp requires a time delay (slow blow) fuse and you have an instantaneous peak type installed, that could do it also.

There are a lot of other unlikely possibilities like a bad capacitor, plate resistor or xfmr winding.