Philips 20PT643F Service Manual page 93

After being buffered by 7369, the differentiated signals are coupled through 2375 and
2380 to the output stage. The output stage is configured into cascode stage and push-
pull operation. The biasing is done by 3373, 3375, 3376, 3380, 3381, 3383, 3374, and
3384. The working voltage of the transistors is settled at half the supply voltage.
At the rising portion of the R/G/B signals, cascode 7380 and 7382 will be operating and
will pull the current through the SCAVEM coil. Contrarily, at the falling portion of the
R/G/B signals, cascode 7373 and 7366 will be operating and will push the current
through the SCAVEM coil.
The capacitors 2362, 2373, and 2381 ground the high frequencies, to prevent high
frequency amplification. The ferrite bead 5376 is for EMC purpose. Resistors 3374 and
3384 determine the output SCAVEM current.
Items 2378 and 3378 are for the fine-tuning for different SCAVEM coil impedances.
They also help to suppress high frequency oscillation. Capacitor 2369 helps to suppress
the high frequency components and also controls the SCAVEM delay.
Synchronization
Inside IC 7200 part D, the vertical and horizontal sync pulses are separated. These 'H'
and 'V' signals are synchronized with the incoming CVBS signal. They are then fed to
the H- and V-drive circuits and to the OSD/TXT circuit for synchronization of the On
Screen Display and Teletext (CC) information.