STV9553

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10.9

Stand-by mode, spot suppression

The usual way to set a monitor in stand-by mode is to switch-off the Vcc (12V).

and the outputs are set to low level (white picture).

To avoid the display of a spot effect during the switch-off phase, it is necessary to adjust the G1 circuitry

(Resistors Rx and Cx, see Figure 19) to pull the G1 voltage to low value during a sufficient time duration.

Figure 19. Stand-by mode, spot effect

Rx

Cx

Typical G1 generator circuitry

Case #2: High Rx.Cx

Case #1: Low Rx.Cx

G1

A spot might appear during

No spot effect

the switch-off phase

EHT

(27kV)

Cathode

G1

R1

-120V

-30V

0V

-30V

-120V

+80V