Don´t overthink it, go for the simplest hypothesis: that stage is oscillating like crazy, all symptoms match that.
1) as suggested by the bedouin, pull V3, the phase inverter and check: do the tubes still oscillate/hum/redplate?
Will add more questions later but start by answering this one.
Throwing 1000 hypothesis on the table and trying to solve all at the same time only muds the field.
2) A couple suggestions about your image posting problems:
a) you linked a TDPRI image which can *only* be seenby currently logged in TDPRI members and nobody else.
You see it because you are so, most others are not, and DIY Audio Forum even less so it can not grab that image to display it here.
b) you are trying to post a PDF as if it were a graphical image, but it is not, so it will not display.
Solution is to open the "advanced" window when you re posting, and **attach** the PDF file as an attachment.
It still won´t display inside the answer but clicking the attachment it will open in Adobe Acrobat or maybe some browser PDF extension.
Hey, look at this, I attached a Fender Blues Jr .GIF image, straight from my own hard drive (so no external hosting involved), and in a format which does not require Adobe Acrobat, can simply be opened in another browser window, and to boot, can be edited (meaning add voltages, whatever)
Even better, you can see a thumbnail inside this answer.
1) as suggested by the bedouin, pull V3, the phase inverter and check: do the tubes still oscillate/hum/redplate?
Will add more questions later but start by answering this one.
Throwing 1000 hypothesis on the table and trying to solve all at the same time only muds the field.
2) A couple suggestions about your image posting problems:
a) you linked a TDPRI image which can *only* be seenby currently logged in TDPRI members and nobody else.
You see it because you are so, most others are not, and DIY Audio Forum even less so it can not grab that image to display it here.
b) you are trying to post a PDF as if it were a graphical image, but it is not, so it will not display.
Solution is to open the "advanced" window when you re posting, and **attach** the PDF file as an attachment.
It still won´t display inside the answer but clicking the attachment it will open in Adobe Acrobat or maybe some browser PDF extension.
Hey, look at this, I attached a Fender Blues Jr .GIF image, straight from my own hard drive (so no external hosting involved), and in a format which does not require Adobe Acrobat, can simply be opened in another browser window, and to boot, can be edited (meaning add voltages, whatever)
Even better, you can see a thumbnail inside this answer.
Attachments
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Thanks, I think I get it now.
And thank you for the other suggestions everybody.....something to be getting on with, I will get back with answers when more is ascertained.
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The DCR measurments of both sides of the primary seem OK, but checking the inductance, not done that yet.