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.
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.