SVT experts question

[catalin gramada]

Hello. I just wonder if this svt really exist...they used an extra PT to increase the screens voltage due to 6146 to 6550 transition from 220V to 350V around ? Still I wonder why don't get any protection just in case of plate supply failed and the screens are still engaged ?

[J M Fahey]

Not surprised if they did.
If they switched but still had, say, 100-200 old style unsold heads , they would definitely not junk them if adding a small extra transformer could "save" them.

Fail safe circuits?

Not too common anywhere, except, maybe, in NASA or the Military or Medical fields