So a quick update: I've rebuilt most of the high voltage circuit on the DMD controller. Still waiting on filter caps to replace C109 & C108. Turns out that both 47kΩ resistors at R102 and R103 were dead, so was hoping replacing those would solve the problem, sadly not.
So my voltages at the DMD are now reading:
Pin 1: -112v (should be -125v)
Pin 2: -98v (Should be -113v)
Pin 4: GND
Pin 5: GND
Pin 6: 5.2v
Pin 8: 69.9v
My 98v AC coming from the transformer is high at just over 110vAC.
So I'm getting a little sign of life on the DMD, will get a few random dots fire up then slowly they start to disappear until the whole display is out once again. I've replaced the ribbon cable from the DMD driver to the DMD and that made no difference, so I'm now suspecting the CPU or the CPU ribbon cable. Would be interested to hear your thoughts/ideas.... I miss my mystery castle IMG_20200925_013534 (resized).jpg