To easily check if lm317 is dead, measure 1.25V accross Adjust and Output terminal, if there is zero volts or 1.5V+ then its dead.
Because your running 450v you need to drop your current.
http://www.eurotubes.com/store/pc/catal ... IIspec.jpgLooking at graphs, at 450V accross the tube the max current is 60mA, if you set it at 60mA then it will redplate because its spot on max disipation.
Another possiblity is that your valves have the wrong screen resistance, the transformer is not designed for el34.
The screen G2 maybe red platting, if this is the case then you can add series resistor before you connect G2 to transfomer, you'd typically be using at least 2watt types.
I recomend checking your valves Cathode to plate voltage, also checking the current, this should not be more than 90% of max disipation. I'd idle power valves at 50-70% of max
When I was trying to transplant some EF183 for my pre amp as cathode followers, I knew nothing about pentodes. I looked at valve wisard as one of my tutorials, it says that its a commonthing that the screen grid burns out before the actuall plate does in power amp.
To check the current of individual valve, eaisly measure drop accross the 1R cathode resistor. V=IR (I=V/R),
Example you measured 60mV accross this resistor, 60/1=60mA of current into valve
If you can tell the the transfomer resistance from B+ tap to G2 connection then I can possibliy use maximum power transfer theory to limit max power into screen and prevent it from burning. max power transfer means the load, screen sees half of supply voltage for max power, at this point the ratio of current draw and voltage is at maximum resulting in maximum power seen for screen.
If screen sees half supply and the transfomer tap see another half, we can find out resistor value needed.
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, but I thought that maybe this noise could lead to some side effect that either fools the LM317 or makes the tubes unhappy on my amplifier.