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Television Sync Separator

Television Sync Separator. What is sync separator. Responsible in keeping the receiver sawtooth deflection oscillators in step with the transmitter sawtooth deflection oscillators.

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Television Sync Separator

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  1. Television Sync Separator

  2. What is sync separator • Responsible in keeping the receiver sawtooth deflection oscillators in step with the transmitter sawtooth deflection oscillators. • A composite video signal having positive going sync pulses is obtained from the output of the video amplifier and is feed to th input of the sync separator

  3. Amplitude separation • Functions of sync separator • Amplitude separation of the sync pulses from the composite video signal • Amplification of the sync pulses • DC restoration • Improvement of the noise immunity preventing loss of the sync because of the noise • waveform separation prevents horizontal and vertical sync pulses from interfering with one another

  4. Sync separator block

  5. Sync separators and deflection circuits

  6. DC restoration • Uses signal bias to set their operating point • It is necessary because composite video signal is often coupled from the video amplifier to the input to the sync separator through coupling capacitor. • Two important function of Bias • Restores the video component of the video signal • Form automatic bias that adjust itself as the signal strength changes so that only the sync pulse tips are responsible for the sync separator conduction

  7. Waveform separation • The differentiator – RC circuit ca be made into high pass filter that is used to block the vertical sync pulses and pass and shape the horizontal sync pulses into trigger voltages for the horizontal oscillator. It is designed for short time constant period • The integrator- low pass filter used to block the horizontal pulses pass and shape the vertical sync pulses for the use of vertical deflection oscillator trigger voltage

  8. High pass differentiator

  9. Low pass filter differentiator

  10. Equalizing pulses

  11. Transistor Sync separator

  12. The transistor noise canceling amplifier

  13. Integrated circuits sync separator

  14. Vertical Countdown circuits Function • Perfect interlace scanning this means that vertical resolution picture is improve because there can’t be any pairing of horizontal scanning lines • The vertical countdown circuit does not require vertical hold control • Changes in the vertical height and vertical linearity control settings can’t have any effect on the vertical sawtooth frequency. In the receivers not using the vertical countdown circuits. Changing this controls will cause picture to roll • This control is one of the master oscillator to generate boot the horizontal and vertical sawteeth.

  15. Master oscillator functions • Video Amplification • AGC processing • Provides voltages to IF, Tuner VHF-UHF • Sync separation • Generate vertical and horizontal pulse • Noise centering amplifier • Eliminate noise pulses • Horizontal AFC • Correcting any frequency error (503.5 khz master scan oscillator) • Master scan oscillator • Operates frequency of 32 times the color horizontal scanning

  16. Vertical Countdown Chips • Provide blanking pulse • Amplified by the buffer stage • Provides horizontal drives • Dividing the 503.5 Khz master oscillator • Provides the drive for the vertical deflection amplifier • Logic circuits divide it’s input signal 525 producing 59.94 Hz

  17. Sync separator problems • Loss of vertical synchronization or picture roll • Loss of horizontal synchronization or picture tearing • Loss of booth horizontal and vertical synchronization • Horizontal pulling or bending • Vertical jitter

  18. Loss of vertical sync • Defective tube, transistor or integrated circuits • An open integrator resistor • Shorted integrator capacitor • Open resistor between the sync separator and the vertical oscillator • A 60 Hz hum present in the sync separator and the vertical oscillator

  19. Loss of vertical sync

  20. Loss of Horizontal Sync • Defective horizontal sync amplifier or transistor • Open or leaky coupling capacitor or horizontal AFC • Increased value or plate or collector load resistor

  21. Loss of horizontal sync

  22. Loss of horizontal and vertical synchronization • Defective transistor in the sync or noise limiter stages • Video coupling capacitor open, shorted or leaky • Video sync isolation resistor is open or increased in value

  23. Loss of booth horizontal and vertical

  24. Horizontal Bending and pulling • The video strip (video IF, tuner and video amplifier) • AGC circuit • The sync separator stage • The horizontal AFC circuit • The low voltage power supply filter

  25. Horizontal pulling

  26. Possible problem are caused by the following components • Defective transistor or IC • Leaky coupling capacitor • Open capacitor in compensating network • Decreased plate or collector load resistance • Defective filtering of power supply

  27. Possible cause of vertical jittering • Defective transistor in sync separator stage • Defective component in the vertical integrator network

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