Television 1 Jess UEAB2006 Television Sync Separator

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Sync separator block

Television 1 Jess UEAB2006 Sync separators and deflection circuits

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 High pass differentiator

Television 1 Jess UEAB2006 Low pass filter differentiator

Television 1 Jess UEAB2006 Equalizing pulses

Television 1 Jess UEAB2006 Transistor Sync separator

Television 1 Jess UEAB2006 The transistor noise canceling amplifier

Television 1 Jess UEAB2006 Integrated circuits sync separator

Television 1 Jess UEAB2006

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.

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Vertical Countdown Chips  Provide blanking pulse  Amplified by the buffer stage  Provides horizontal drives  Dividing the Khz master oscillator  Provides the drive for the vertical deflection amplifier  Logic circuits divide it’s input signal 525 producing Hz

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Loss of vertical sync

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Loss of horizontal sync

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Loss of booth horizontal and vertical

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Horizontal pulling

Television 1 Jess UEAB2006 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

Television 1 Jess UEAB2006 Possible cause of vertical jittering  Defective transistor in sync separator stage  Defective component in the vertical integrator network