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previous: K BULL Re: Ian.... -- 10/23/2000 4:54 PM view thread

pulling out tubes with B+ ON

10/23/2000 5:23 PM
tommy
pulling out tubes with B+ ON
If there is no B+ current flowing anywhere, then all the power supply caps would reach a steady-state voltage equal to the highest voltage reached by the rectifier section.  
 
Bassman for example: 520 V all along the power supply sections with all tubes pulled out, assuming no leakage in elecrolytics. The resistors that usually drop voltage between the different power supply sections as you move toward the preamp don't have any current flowing through them, so no voltage drop.  
 
If you leave preamp tubes in, then you will get drops across some or all of these resistors, the amounts depending on which tube positions are filled. The first (few) filter cap(s) will see a higher than normal value, although if it is properly designed, this should be no problem.  
 
Chris