Sharp XV-C1E Service Manual page 27

BRIGHT (pin No. 43)
l
Used to receive DC voltage for brightness adjustment.
GAMMA 1, GAMMA 2 (pin Nos. 44 and 45)
l
Used to receive DC voltage to set a
gamma-correction DC voltage gain
switching point. (See the figure at
right.) The Gamma 2 terminal is pre-
set inside the IC.
PEAK LIMITER (pin No. 46)
l
Used to receive DC voltage to set the
white peak limiter level for primary-
SUB CONTRAST B (pin No. 47)
l
Used to receive DC voltage for fine adjustment of the B signal' s contrast. This terminal is preset inside the IC.
SUB CONTRAST R (pin No. 48)
l
Used to receive DC voltage for fine adjustment of the R signal' s contrast. This ferminal is preset inside the IC.
ii) Circuit behavior
ACC detector, ACC amplifier
l
They form an ACC loop and serve to detect the peak of the burst signal amplitude.
VCO, APC detector
l
The VCO local oscillation circuit is of Pierce crystal oscillator type and functions as a crystal unit. The APC
detector phase-detects the burst signal and the VCO oscillation output signal. The resulting detection voltage
is used to control the VCO' s oscillation frequency and to form a phased-locked loop. By doing so, no readjust-
ment is needed.
The detector is used to phase-detect the burst signal and the VCO' s oscillation output signal.
Picture adjustment circuit
l
The value " Q" of the luminance signal delay line is changed in order to adjust the frequency characteristic.
Various AGC characteristics can be achieved depending on the luminance signal' s APL. The luminance
signal is fed to the filter at pin (17) to get rid of the high-frequency components. The resulting signal goes to
the AGC detector to detect the peak.
Filter adjustment
l
The resistance between pin (12) and GND can be regulated to adjust the filter' s frequency characteristic.
External input switch
l
The INT and EXT signals can be switched over by the control signal coming to pin (l).The switch is of high-
speed type.
output
2 7
XV-Cl E
PEAK
LIMITER
Input