5-8
5. INTERFACE OF MODE DISCRIMINATING CIRCUIT AND CH. SELECTION MICOM
The result of mode ident. explained in Section 3 is converted to d.c. and is supplied to pin 15 of Ch. Selection Micom ICA01.
VGA480
CA27
M0.01
QA05
RN1202
RA54
16K
VGA400
CA28
M0.01
QA06
RN1202
RA51
16K
VGA350
CA29
M0.01
QA07
RN1202
RA52
11K
LOW FREQ
CA30
M0.01
QA08
RN1202
RA53
7.5K
NO SIG
CA31
M0.01
QA09
RN1202
RA50
7.5K
RA49
33K
ICA01
+5V
RGB MODE
Fig. 8
Micom ICA01 recognizes kind of input signal by the voltage
at pin 15, reads out data which are stored in memory and
controls operation of deflection circuit like width, distortion
and picture position, and send them to circuits.
The memories controlling this deflection circuit are equipped
by 1 set for TV mode, and by 4 sets for RGB mode. In RGB
mode, 3 sets are used for VGA and reminder 1 set is used for
Macintosh and other signal than VGA. And when signal is
not input in RGB mode, micom supplies switching signal so
that deflection circuit only operates in TV mode.
When frequency of input signal is lower than 28kHz, micom
switches over automatically the size and display position of
OSD character.
The relation of input signal state and voltage at pin 15 of
ICA01 is shown in Table-7.
Input signal AD conversion value (H) Center voltage (V
)
Kind of memory
Sub data User data
E0 ~ FF 4.71 A A’
C0 ~ DF 4.08
VGA480 A0 ~ BF 3.45 B B’
VGA400 80 ~ 9F 2.82 C C’
VGA350 60 ~ 7F 2.20 D D’
LOW FREQ 40 ~ 5F 1.57 A A’
No signal
20 ~ 3F 0.94
00 ~ 1F 0.31
TV mode E
Mac. and other
than VGA
Table-7
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