Been through all the board cannot see why this is occuring.
Using IRF9Z24N from Farnell
Transformer is in correctly (Pri to Output Jacks, or “Backwards”)
R35 & R36 are 200k
using LTC1661 DAC
Can provide scope shots.
How can I measure Vth of these IRF9Z24N devices ( My Analog theory is not what it used to be )