Hitachi CP2155TA, Руководство по обслуживанию

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9
COLOUR DECODER COLOUR DECODER
The luma signal processing and colour decoding are
implemented by IC504. The luminance and chrominance
signals are separated internally. A delay line is also
incorporated to compensate for the difference between the
luma and chroma processing times. The chrominance signal
is demodulated and the two colour difference components
are fed through IC503, a 64ns charge coupled delay line.
There are no adjustments required on the colour decoder.
On-Screen Display
The micro-controller on-screen display (OSD) supplies
blanking and RGB signals for overlaying the television
picture. Pin 35 of IC701 provides blanking pulses which are
applied to pin 26 of IC504 via TR301, to turn off the decoder
RGB output so that the OSD is clearly visible. The RGB
signals from pins 32, 33 and 34 of IC701 are applied directly
to the tube-base via TR302 to TR304 and the text drive
colour balance presets RV321 and RV322.