Video display protection circuit

Apparatus for applying beam cut-off bias to the grid of a kinescope, comprising:

• a capacitor having first and second electrodes;
• a source for providing a beam cut-off control signal;
• a first switching circuit responsive to a first condition of said control signal for allowing a first, charging current to be supplied to said first electrode of said capacitor from a first voltage source when beam cut-off is not desired, and responsive to a second condition of said control signal for coupling said first electrode of said capacitor to a source of reference potential when beam cut-off is desired;
• a second switching circuit having a first electrode coupled to a second voltage source, a second electrode coupled to said second electrode of said capacitor and to said grid of said kinescope for coupling a second voltage source to said second electrode when enabled and isolating said second electrode from said second voltage source when disabled, and a third electrode;
• and
• a third switching circuit for allowing a second current that is independent of said first current to flow through a second circuit path to said second switching circuit to enable said second switching circuit when beam cut-off is not desired and for disabling said second switching circuit when beam cut-off is desired,
• said second circuit path including first and second resistors connected in series between said source of said first voltage source and said third electrode of said second switching circuit,
• said third switching circuit being coupled between said first switching circuit and a connection point between said first and second resistors.