| 摘要 |
A television switched synchronous vertical deflection (SSVD) circuit produces vertical deflection current by integration of horizontal retrace pulses. Vertical retrace blanking is provided by a monostable multivibrator triggered from the vertical synchronizing signals, and coupled to the kinescope to provide blanking in its unstable state and to unblank in its stable state. Failure of the horizontal retrace pulse supply to the SSVD circuit causes vertical deflection to cease, resulting in a line across the center of the screen. An inhibiting circuit coupled to the multivibrator feedback loop and to the horizontal retrace pulse supply prevents the multivibrator from assuming its stable state except during the presence of a horizontal retrace pulse.
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