7-10
2-2 Hor OSC frequency Control Circuit
To synchronizing hor deflection circuit to input signal, the
circuit controls free-running frequency of hor osc circuit
responding with input signal.
In RGB input, by utilizing output voltage of F/V convert
circuit as mentioned above, such control voltage as free-
running frequency automatically follows to input signal
frequency, is applied to pin 8 of ICH08.
But in TV mode, the circuit changes to add the fixed voltage,
not F/V convert voltage.
The reason is to prevent that circuit operation becomes
unstable, because F/V convert voltage varies largely due to
noise in reception of no signal and vacant channel. This fixed
voltage is adjusted with variable resistor RH35, to set free-
running frequency of TV mode.
ICH13 the same as above sync signal is used for switching.
The signal to switch the IC is sent though QH17. (See Fig. 29)
When the mode is selected with remote unit or key of TV set,
channel selecting IC sends data which makes voltage at
pin13 of DAC ICX001 5V or 0V, using T-Bus line. This
voltage at pin13 of DAC is supplied to base of QH17 through
buffer amp. QX02. This voltage becomes 5V in RGB mode,
and 0V in TV mode.
Fig. 30
2-3 Hor Phase Shift Circuit
The circuit can adjust hor picture position, by utilizing phase
shift function contained inside ICH08 (LA7860).
This control voltage is supplied from pin10 of DAC IC
ICX001 which receives data from micom ICA01 through T-
Bus line. Therefore, the voltage can be adjusted by remote
unit.
T-Bus
ICA01
MICOM
ICX001
DAC
10
3
2
ICK09
1
3
ICH08
LA7860
Only in RGB mode, the circuit is designed so that user can
adjust to requested condition with remote unit or key of TV
set.
Adjusting data are stored in memory ; Factory adjusting data
are one for TV and four for RGB, User adjusting data are four
for RGB.
Fig. 31
ICH04
IR9331
1
6
5
7
15
1
2
ICH13
12
13
14
ICH05
ICH05
ICH08
8
14
+9V
RH35
NTSC
fH ADJ
+12V
