Hi Alan,
That 68R resistor looks like a later design tweak: it puts some -ve bias on the valve so that in the absence of drive from the 12AU7, the 5763 does not draw a heavy current and do nasty things to it and the pri. wndg. of the xfmr. primary. I looked at your table of voltages: what is the voltage at the cathode of the 5763? That's the really critical measurement which we need here. Whatever, it's clear that the cct. isn't oscillating: I think you'll find that R516 is open-cct.
Al.
That 68R resistor looks like a later design tweak: it puts some -ve bias on the valve so that in the absence of drive from the 12AU7, the 5763 does not draw a heavy current and do nasty things to it and the pri. wndg. of the xfmr. primary. I looked at your table of voltages: what is the voltage at the cathode of the 5763? That's the really critical measurement which we need here. Whatever, it's clear that the cct. isn't oscillating: I think you'll find that R516 is open-cct.
Al.
