NEC MultiSync V520 Service Manual page 70

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
R17
15
100
*L1 is a Ferrite Bead
67
R21 47k
RED DRIVE ADJ.
POT3
100K
GREEN DRIVE ADJ.
POT1
100K
BLUE DRIVE ADJ.
POT2
100K
RGB CUTOFF ADJ.
POT4
100K
L1
R19
RED VIDEO OUT**
R20
430
2.4k
C16
100 µ F
R18
GREEN VIDEO OUT**
R17
430
2.4k
R15
BLUE VIDEO OUT**
R16
430
2.4k
R17
BLANK GATE
100
CLAMP GATE
**50 Ω Termination to
be Used at Outputs
TL/H/12355-12