Quote:
Originally Posted by dtvmcdonald
... It terminates (for DC) in
the plate of the first vertical sweep output tube![/B] The
total resistor chain is about 9 megs.
If the first vertical amp tube were to lose transconductance
a lot, the plate voltage would drift up to about 2 kV! I do
of course note that the plate resistors in the deflection circuits
are all in the megohm range, as this is electrostatic deflection
which should draw no current. Its not high power like in magnetic
deflection/flyback HV generation sets.
What would happen to a 12SN7 with 2 kV on the plate?
(And to its socket?)...
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That's a typical design for electrostatic sets. The AC line voltage doubler doesn't produce a large enough B+ voltage to drive the CRT deflection plates so it's derived form the HV divider chain. Arcing in the vertical tube or socket does sometimes occur.