5-4
The outputs of VGA three modes are tabled as in Table-5.
Kind
ICH01 M52346SP ICH02 TC4028BP
pin 6 pin 8 pin 18 pin 19
pin 11
(D)
pin 12
(C)
pin 13
(B)
pin 10
(A)
output
(High)
VGA480 Nega Nega H H L H H H pin 4
VGA400 Nega Posi H L L H L H pin 6
VGA350 Posi Nega L H L H H L pin 7
Table-5
As shown in table above, since the result of frequency discrimination is input to pin 12 (c) of decoder ICH02, in case that
frequency of input signal is lower than 28kHz, the mode is discriminated as not VGA mode even though polarity of sync signal
is same combination as VGA.
Operation of frequency discriminating circuit is explained as follows, and configuration is shown in Fig. 3.
+12V
RH09
12K
DH03
CH12
SL100P
1SS176
or
1SS133
RH13
10K
RH12
10K
RH14
10K
RH15
5.6K
CH13
T1200
8
7
6
5
ICH04
IR9331
F/V CONVERTER
1
2
3
4
14
13
12
11
10
98
DH04
RH22
560KG
RK58
33KG
DK17
RH23
1.8KG
RK59
12KG
RH20
1/4W
47KF
RH21
1/4W11KF
ICH05
TA75902P
or LM2902N
1
2
3
4
5
6
7
F/V
RH75
8.2K
CK17
M680
1SS176
or
1SS133
1SS176
or
1SS133
CH15
16V47
RH11
15K
RH10
18K
QH03
2SC752Y
RH64
33K
QK11
2SC1815Y
or 2SC17405,Q
or 2SC1685Q
CK24
M0.015
CH14
M2.2
RH18
1/4W
82KF
RH16
1/4W4.7KF
RH17
2KB
F/V ADJ
RH28 580K
RH24
1/4W3.3KF
1
2
3
RH26
1/4W1.8KF
QH10
2SC1815Y
or 0
DH06
RD5.1ESAB1
or UZ5,1BSA
RH30
1/4W
8.2KF
RH29
1/4W
13KF
QH09
RN1202
LOW FREQ
+5V
Hori. Sync
H. OSC
Def. circuit
H.Size
RH19
68K
RH90
27K
RH48
22K
2
3
1
RH27 680
RH52
10K
Fig. 3
ICH04, F/V (Frequency-Voltage) converter, produces the voltage proportional to hor. scan frequency of input signal.
This voltage is amplified in ope. amp ICH05. The comparator which is consisted of ICH05, compares frequency to operate
so that emitter voltage of OH10 becomes HIGH level when the frequency is high.
To Next Page
Loading...
