To get to 5v, I am turning the control knob to its maximum. I seem to be getting some variability there as I warmed up the amp for 45 minutes, turned it all the way up which got me barely to 5v then checked it 5 minutes later to be 5.25 v. Is this indicative of a tube issue - if so, which tube(s)? Or is it a function of variability in my mains voltage?
I noticed my meter dips below the zero mark when turned off. Should it be exactly at zero? If so, do I set it using the slotted plastic head at the base of t
It could be static electricity that is preventing the meter from going to zero. I have it happen to one my tube tester until the static electricity has been discharged. The screw is the mechanical zero for the meter. You only need to adjust it one time if the amp has been move or shipped from another location.