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J: S/N 030,001 to 031,450
(
IFB-12 (OLD):
U/C, AEP: S/N 040,001 to 041,750
(
J: S/N 031,451 and later
IFB-12 (NEW):
U/C, AEP: S/N 041,751 and later
2-1. GENERAL
This board is a 5-BNC analog input/output board which is
able to serve as an input or output board using the IN/OUT
switch. The output board is equipped with a feed
compensation function for cable, and a compensation rate
can be selected with the compensation mode switch
according to the length of the coaxial cable.
2-2. POWER SUPPLY CIRCUIT
+12 V to +15 V power is supplied from the 96-pin
connector CN3 (A4, B4, and C4) (IFB-12 (OLD)), J1 (A4,
B4, and C4) (IFB-12 (NEW), IFB-12A) terminals. The IN/
OUT select switch is used to select the power for the input
or output circuit.
1 When the IN/OUT switch is set to the IN side and CN3
(C19) (IFB-12 (OLD)), J1 (C19) (IFB-12 (NEW), IFB-
12A) becomes "LOW", Q25 is turned OFF, Q28 is
turned ON, and relays RY1 to RY5 (IFB-12 (OLD)),
RL1 to RL5 (IFB-12 (NEW), IFB-12A) are turned ON
by IC25, and the power supply line is connected to the
input circuit as well as the LED lights up.
2 When the IN/OUT switch is set to the OUT side and
RGB/VIDEO terminal CN3 (A17) (IFB-12 (OLD)), J1
Input mode
DIP SW
RGB
COMPONENT
HDTV Y Pr Pb
HDTV GBR
C VIDEO
S VIDEO
IFB-12/12A
SECTION 2
CIRCUIT DESCRIPTIONS
)
)
Table 1
RGB/VIDEO
(A17)
1
H
2
M
3
H
4
H
5
L
6
L
(A17) (IFB-12 (NEW), IFB-12A) becomes "MIDDLE"
or "HIGH" (+1.7 V to +5.2 V), Q25 is turned OFF,
Q28 is turned ON, and relays RY1 to RY5 (IFB-12
(OLD)), RL1 to RL5 (IFB-12 (NEW), IFB-12A) are
turned OFF by the comparator IC26 and IC25, the
power supply line is connected to the output circuit as
well as the LED lights up. When the RGB/VIDEO
terminal becomes "LOW" (input is a video signal), the
output circuit does not function.
3 R208, Q22, Q23, and Q24 serve as a current detection
protector. When excessive current flows (higher than
1.2 A), Q22, Q23, and Q24 are turned ON, and Q28 is
turned OFF (power is shut off) as well as protector
terminal CN3 (A2) (IFB-12 (OLD)), J1 (A2) (IFB-12
(NEW), IFB-12A) is connected to GND, and failure is
indicated to the outside.
2-3. INPUT MODE
When the IN/OUT switch (S2: IFB-12 (OLD)), (SW2:
IFB-12 (NEW), IFB-12A) is set to the IN side and SEL
(C19) terminal becomes LOW, this mode is set.
1
1
1
1
1 Input mode setting (Table 1)
When the DIP switch is turned ON according to the input
signal, RGB/VIDEO, VIDEO/YC, and CODE1 control
signals are passed through transistors Q2 to Q8 and output
to CN3 (A17, C17, and B16) (IFB-12 (OLD)), J1 (A17,
C17, and B16) (IFB-12 (NEW), IFB-12A) according to the
input mode. This informs external devices such as a
switcher, etc. of the input signal type.
VIDEO/YC
CODE1
(C17)
(B16)
H
H
H
H
L
L
H
L
H
H
L
H
Related
transistor
Q4
Q5, Q6
Q5
Q8
Q7, Q8
2-1(E)
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