NEC MultiSync V720 Service Manual page 69

Test Circuits
J1
RED OSD INPUT
GREEN OSD INPUT
BLUE OSD INPUT
OSD INPUT SELECT
RED VIDEO IN
GREEN VIDEO IN
BLUE VIDEO IN
V
CC
R11
100k
VIDEO CONTRAST
POT5
100K
C12
0.1 µ F
OSD CONTRAST
POT6
100K
FIGURE 2 LM1281 OSD Video Preamp Demonstration Board Schematic
C2
0.1 µ F
R1
1
R2
2
R3
3
R4
4
R6
C3
5
R5
50/75
6
C5
0.1 µ F
7
R7
C4
8
33
R8
50/75
9
C6 C7
100 µ F 0.1 µ F
10
R9 C9
11
R10
10 µ F
33
50/75
12
C8
0.1 µ F
13
C10
0.1 µ F
14
C11
0.1 µ F
V = + 12V
CC
C1
100 µ F
28
C21
0.1 µ F
27
C20
0.1 µ F
26
C19
0.1 µ F
25
C18
0.1 µ F
24
C17
0.1 µ F
23
LM1281
TOP VIEW
22
C15
0.1 µ F
21
20
19
C14
0.1 µ F
18
17
C13
0.1 µ F
16
15
*L1 is a Ferrite Bead
66
R21 47k
POT3
100K
POT1
100K
POT2
100K
POT4
100K
L1
R19
R20
430
2.4k
C16
100 µ F
R18
R17
430
2.4k
R15
R16
430
2.4k
R17
100
R17
100
**50 Ω Termination to
be Used at Outputs
RED DRIVE ADJ.
GREEN DRIVE ADJ.
BLUE DRIVE ADJ.
RGB CUTOFF ADJ.
RED VIDEO OUT**
GREEN VIDEO OUT**
BLUE VIDEO OUT**
BLANK GATE
CLAMP GATE
TL/H/12355-12