The drive o/p pin1 of U401 delivers a drive current of 1.5mA at 5V output through R302
to U402 pin1.
2.3.3
Sync separator
:
The video input through C401, R401 and filter C402 to pin 5 of U401.The Sync separator
is designed such that the slicing level is independent of the amplitude of the Sync pulse. The
black level is stored at pin7 by C404. The slicing level is stored at pin6 by C403 and decided
by R403.
2.3.4 Phase detector:
The phase detector circuit is connected to pin8. The circuits are activated depending on
the voltage of pin18 and the state of the Sync pulse noise detection circuit, C405, C406,
R405.
2.3.5 Supply (pin9, 10 and 16)
:
U401 can start operating by application of a very low supply current into pin16. When the
starting circuit is taken from pin10 via internal diode, and the voltage on pin16 will stabilize
to a typical value of 9.4V
2.3.6 Horizontal oscillator, horizontal output transistor, and second phase detector (pin11, 12,
14 and15):
The oscillator is connected to pin15. An external RC; C409, R412, VR401; sets the
frequency combination between pin15 and ground. The open collect horizontal output is
connected to pin11. The duty factor is set by an internal npn emitter follower stage
connected to pin14. When no flyback pulse is detected at pin12 the duty factor of the
horizontal output stage is set to 50%.
2.3.7 Mute output and 50/60HZ identification (pin13)
:
Pin13 has the possibility for 50/60HZ identification. A pull-high resistor R408 achieves
the function.
2.3.8 Sandcastle output (pin17):
The sandcastle output pulse generated at pin17.
2.4 Vertical Deflection Block
• Power amplifier
：
10
