From: spam@flippers.com   
      
   dm08262000 wrote:   
   > Restoring this from the bottom up. The 5u4 blows every time I plug the   
   > speaker connector in, even with speaker not connected. Voltages are good   
   > on tube,has been re-capped and can't find a short anywhere. Any help   
   > will be much appreciated!!   
   >   
   >   
   >   
   >   
      
   That is strange, sounds like the 5U4 filament is being shorted to ground   
   somewhere as I assume that is what is blowing on your tube.   
      
   The speaker connector provides the ground path for the HV secondary   
   (center-tapped) winding of the power transformer, the other sides of the   
   secondary HV winding are supposed to be connected to the plates of the   
   5U4. The 5U4 filament (5.0VAC) is supposed to be only connected to the   
   transformer and is floating otherwise - this is the source of the B+   
   voltage in the system.   
      
   John :-#)#   
      
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