Just to continue the above, The guesstimate value for the HT mains dropper resulted in the HT being exact to the volt!! But that dropper sure does belch out some heat
It dissipates 30 W for the heaters and another 15W for the HT. So 45W in total. Granted, some of that would have been shared with the metal rectifier originally, but even so that amount of heat in that part of the chassis, it's no wonder the components in the frame timebase cooked!! It wasn't long before the solder melted and the wire fell off
(It is only for testing at the moment)
The main issue is that the EHT is very low so the picture balloons when the brightness is turned up. It measures 8KV but should be about 16KV. There is a very healthy arc from the overwind but no visible heater in the U26 rectifier. Does the U26 have an obviously glowing heater when it's running? I don't have a spare to hand so can't change it yet but I somehow suspect it's ok. The boost is also low at 400 odd volts so I have yet to investigate further.
I need to get some signals into it so I can do some more checks so that will be the next part of the plan.
All the best
Nick