TRS-80 Model 12 crt substitution

I can confirm that glass is very good insulator too. Mere dirt even greasy smear even a incomplete air-seal (HV cup) is enough for HV to escape with a (SNAP!, crackling or hissssing). Even a tight pinhole in rubber/silicon/plastic insulations that can hold back water didn't stop HV's dramatic exit. That one I had one, had to find it with HV probe waving around each HV cup (three in a set for projector and that particular set has secondary HV hat loosely placed over each HV cup and kept in place by wedge force) till I see some deflection it apart and finally found the burn spot on the metal HV clip that matched a microsopic pinhole in the rubber cup. Oh, as other have said about the "power" of the HV it is very powerful enough to "eat" through if insulations has flaws in it. I see this often in flyback transformers & botched HV splitter installions. One time I seen "tufts" of impossibly fine magnet wires for HV stuck out of crack encircling flyback's round body where flyback transformer housing split open with a BANG according to owner whom heard the noise. For this reason, manufacture of HV stuff had to be super clean and quality stuff, HV resistors, caps, diodes, very carefully manufacturing steps, vacuum vessel to "boil" potted units prior to curing. That's the reason for not filling potting stuff to the brim. It's below the rim of housings about 1cm depth. Deduced from my reasonings. 33 to 35KV is "asolute" max for consumer stuff including projectors. Anybody care to raise reason behind this HV "wall"? Not just for x-ray reasons. I use is I think 180 Ohm 20W sandbar resistor for both HV and main filter caps as discharger. Much gentler on stuff and sanity. Cheers, Wizard