[cathoderay57]

Hi Steve. Re: voltage measurements: UY85 rectifier looks OK; UABC80 should have 50v or so on the triode anode only, I assume when you said anodes it was a typo. UL84 screen grid is a tad low probably because R28, the 5.6k you mentioned, has gone high. Annoyingly Trader 1474 doesn't show the valve currents in the table, only the voltages (whereas the older sheets did). So looking up typical currents in the data book we have, passing through R28:
UL84 screen 5mA; UABC80 anode 1mA; UCH81 screen 8.1mA; UF89 anode 12mA and screen 3.9mA giving a total current of 30mA. That's worst case as with reduced emission for ageing valves the currents will generally be less. Therefore 30mA through a 5.6k resistor dissipates 5W. If you used a 5W it would run extremely hot so I would recommend sticking a 10W resistor in. Alternatively use two 5W 2.7k in series or two 5W 12k in parallel. Cheers, Jerry