A colleague reports significant variations in an actual II-80 from what is given in the schematic. He says that the output stage cathode circuits (4) each consist of 270R in parallel with a series combination of 220uF and 4R7. The website above has 460R || 100uF. He measured voltages as follows:
Vp= Approx. 478-480vdc
Vs = 241vdc
Vk = 18.1vdc to 18.8vdc depending on which tube was measured.
I am wondering whether Vs indicates a fault, as it seems terribly low to me.